Renewable Energy Global Innovations features: Water build-up and evolution during the start-up of a PEMFC: Visualization by means of Neutron Imaging

Significance Statement

The need to prolong the life of proton-exchange membrane fuel cell has of late accelerated. Researchers have realized that water management in the fuel cell has a major influence in the cell and stack performance. More so, it directly affects the durability of the cell components. Normally, the quantity of water generated at the cathode is directly proportional to the current density, therefore, the water removal capability of the cathode is a critical parameter for ensuring ultimate fuel cell performance.

Additionally, an appropriate water balance in the cell is crucial for durability purposes. Water evolution and build up during the start-up of proton-exchange membrane fuel cell is equally important, especially, since the relative humidity conditions around the electrodes are prone to variations. Therefore, to strike this balance, a technique that enables both the quantification and visualization of the local water content within the cell during operation, would be crucial. Besides, most of the two-phase flow studies found in literature center on the steady state behavior of water in the proton-exchange membrane fuel cell, whereas relatively few works address the transient behavior of the water build-up and evolution.

Alfredo Iranzo and colleagues proposed a study on water build-up and evolution during the start-up of a proton-exchange membrane fuel cell: Visualization by means of Neutron Imaging – a technique that allows visualization and quantification of local water content in the cell during operation simultaneously. Their main objective was to further look into the water build up and evolution during the start-up the cell, for a set of different anode and cathode relative humidity conditions. Their research work is published in International Journal of Hydrogen Energy.
Briefly, the empirical procedure involved operating a commercial 50 cm2 proton-exchange membrane fuel cell with serpentine flow fields at 2.0 bars and 60 C with varying relative humidity values for the inlet reactants. Between each tests, the team ensured that the cell was decompressed and the liquid water was thus flushed out. They then utilized Neutron Imaging to record the liquid water build up and the time evolution during each experiment. Eventually, they conducted a qualitative and quantitative analysis using the recorded data.

The research team mainly observed that the dynamics of the water build up comprises of three main stages, where the main difference is the local liquid water accumulation rate. They noted that the onset location for the water appearance in the flow field channels was determined by the flow field design, gravity and gas flow direction along the serpentine path. Eventually, they analyzed the time evolution of the water progressive accumulation along the flow field channels and cell active area.

Herein, a comprehensive experimental investigation of channel liquid water distributions in a 50 cm2 Proton-exchange membrane fuel cell with serpentine flow field has been presented. Neutron radiographs have been used to determine water build-up and time evolution of the liquid water content and distributions for a set of several varying operating conditions of the cell. The outcomes of this study are impressive and provide crucial insight into the liquid water dynamics during cell transients that can contribute to a better understanding and optimized design of cell components and operating conditions, which should result in an optimized performance of the cell dynamics in applications such as automotive fuel cells dealing with driving cycles.

About The Author

Alfredo Iranzo obtained a Masters Degree in Chemical Engineering at the University of Zaragoza, Spain, in 2000. After five years working in the Fluids Business Unit at ANSYS Germany in Otterfing (Munich, Germany), he obtained a Master of Science in Thermal Energy Systems at the University of Seville, Spain, in 2010, and a PhD degree in 2011 with a research work on CFD PEM Fuel Cell modelling and experimental validation. His current research interests include PEM Fuel Cell modelling and experimental techniques, solar hydrogen production and other CFD activities in Chemical and Energy Engineering.

Alfredo Iranzo is author of over 25 publications in JCR international peer-reviewed scientific journals and two book chapters. He is member of the Editorial Board of two JCR international peer-reviewed scientific journals: “International Journal of Hydrogen Energy” and “Engineering Applications of Computational Fluid Mechanics”. He has been included in “Who´s who in Science and Engineering”, Ed. Marquis, in the 2012th and 2015/16th editions.

Reference

Alfredo Iranzo, Antonio Salva, Pierre Boillat, Johannes Biesdorf, Elvira Tapia, Felipe Rosa. Water build-up and evolution during the start-up of a PEMFC: Visualization by means of Neutron Imaging. International journal of hydrogen energy volume 42 (2017) pages 13839-13849.

 

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Renewable Energy Global Innovations features: Reactor core transient analysis of innovative high-level nuclear waste transmuter with metal fuel

Significance Statement

Nuclear energy presents a sustainable energy supply and cheap electricity. It has been indicated to minimize the emission of greenhouse gases. Unfortunately, nuclear energy also has some shortcomings in sustainability. One important issue on this emanates from the disposal of spent fuels discharged from the reactors. Therefore, transmutation and partitioning of the minor actinides in the spent fuels will be necessary for the self-sustainment of the nuclear industry.
The radiotoxic inventory of the geological repositories will be reduced up to a factor of 100 if minor actinides and plutonium will be completely transmuted and recycled. Researchers have indeed investigated extensively with varying fuel cycle strategies, reactor systems and neutron spectrums. Fast reactors have been identified as the most promising candidates.
Unfortunately, transmuting minor actinides in fast reactors have been found to have significat safety concerns on the performance of the reactor cores. It has been demonstrated that the high amount of minor actinides such as neptunium and americium, initiates severe deterioration of coolant density reactivity feedback in the heavy-liquid-metal-cooled fast reactors. Researchers have found that it is important to reduce the core power by about 4% for every 1% addition of americium loaded in a lead-cooled fast reactor. If minor actinides are added in a reactor core, its neutronic safety performance becomes worse.
Since the economy of a nuclear reactor is dictated by the operational power level, it is uneconomical to undertake minor actinides transmutation in a critical fast reactor, which must be operated in a reduced power level in a bid to maintain sufficient safety margin. Fortunately, the accelerator driven subcritical system has a larger safety margin in minor actinides transmutation as opposed to the critical fast reactors.
In view of the fact that transmutation in the current operational reactors is insufficient and poses some safety concerns, Professor Youqi Zheng and colleagues from Xian Jiaotong University, China, proposed an accelerator-driven subcritical transmuter, which was named highly efficient industrial transmuter (HEIT) in a move to address these concerns. Their research work is published in International Journal of Energy Research.
The proposed system utilizes uranium-free metallic dispersion fuel and has high power density. The authors focused on the transient analysis of the highly efficient industrial transmuter in order to stablish its feasibility in the future nuclear applications. They analyzed cladding stresses, cumulative creep damage fractions and temperatures. In addition, the researchers investigated the burnup dependence and evaluated three transients: the beam overpower, the unprotected transient overpower, and the unprotected loss of flow.
The authors observed that the highly efficient industrial transmuter core remained safe without scram in a majority of transient cases. From the results, there was indicated that there will be enough safety margins from fuel pin failure. In the unprotected loss of flow transient, the cladding cloud exceeded the rapture limit in approximately half an hour when no shutdown responded. This was reference to the positive coolant density coefficient caused by the minor actinides loading.
The creep damage fraction as well as the maximum temperature was observed to change with the depletion owing to the delay heat fraction and power distribution variation. For the unprotected loss of flow transient, the end of lifetime was bounding, while for the case of beam overpower and unprotected transient overpower transients, both the end of lifetime and the beginning of lifetime ought to have been accommodated.

About The Author

Youqi Zheng
Associate Professor
School of Nuclear Science and Technology
Xi’an Jiaotong University
Xi’an, Shaanxi 710049, China
Tel: +86-29-82668692 Fax: +86-29-82668916
Email: yqzheng@mail.xjtu.edu.cn

Education:

Ph.D, Nuclear Science and Technology, Xi’an Jiaotong University, 2011
B.D, Nuclear Engineering and Technology, Xi’an Jiaotong University, 2006

Experience:

Jan. 2014- …, Associate Professor, School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an, China.
 July. 2015- July. 2016, Post-doctoral researcher, Ulsan Institute of Science and Technology, Ulsan, Korea.
Apr. 2011- Dec. 2013, Lecturer, School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an, China.

Research Fields:

Reactor physics; Advanced nuclear reactor R&D; High-level nuclear waste transmutation; Computational method for reactor core analysis

Awards:

First Class Prizes of Shaanxi Technical Invention Award, 2017
Third Class Prizes of China National Nuclear Corporation Scientific and Technological Progress Award, 2017
Young Talent Supporting Project of Chinese Association for Science and Technology, 2015
Outstanding Doctoral Dissertation Award in Shannxi Province, 2013

Selected Publications:

1. Youqi Zheng^*, Xunzhao Li, Hongchun Wu, Effect of high-energy neutron source on predicting the proton beam current in the ads design, Nuclear Engineering and Technology, in press, http://ift.tt/2l58pXh.
2. Youqi Zheng, Sooyoung Choi, Deokjung Lee. A new approach to three-dimensional neutron transport solution based on the method of characteristics and linear axial approximation, Journal of Computational Physics, 111: 271-279, 2018.
3. Youqi Zheng, Deokjung Lee, Peng Zhang, et al. Comparisons of S-N and Monte-Carlo methods in PWR ex-core detector response simulation, Annals of Nuclear Energy, 101: 139-150, 2017.
4. Youqi Zheng^*, Yunlong Xiao, Hongchun Wu, Application of the virtual density theory in fast reactor analysis based on the neutron transport calculation, Nuclear Engineering and Design, 320: 200–206, 2017.
5. Youqi Zheng^*, Mingtao He, Liangzhi Cao, et al., Reactor core transient analysis of an innovative high-level nuclear waste transmuter with metal fuel, International Journal of Energy Research, 41(9): 1322-1334, 2017.
6. Mingtao He, Youqi Zheng^*, Hongchun Wu, et al. Assessment of transient characteristics of fast reactors and influences of minor actinides using neutron transport method, International Journal of Energy Research, 41(14): 2194-2205, 2017.
7.  Mingtao He, Hongchun Wu, Youqi Zheng^*, et al. Beam transient analyses of Accelerator Driven Subcritical Reactors based on neutron transport method, Nuclear Engineering and Design, 295: 489–499, 2015.
8. Xunzhao Li, Shengcheng Zhou, Youqi Zheng^*, et al. Preliminary studies of a new accelerator-driven minor actinide burner in industrial scale, Nuclear Engineering and Design 292: 57–68, 2015.
9. Yunlong Xiao, Hongchun Wu, Youqi Zheng^*, et al. Neutronics studies on the feasibility of developing fast breeder reactor with flexible breeding ratio. Journal of Nuclear Science and Technology, 53(1): 129-138, 2015.
10.  Youqi Zheng, Hongchun Wu, Liangzhi Cao, et al. Daubechies’ Wavelet Method for Angular Solution of the Neutron Transport Equation. Nuclear Science and Engineering, 164(2): 87-104, 2010.

Reference

Youqi Zheng, Mingtao He, Liangzhi Cao, Hongchun Wu, Xunzhao Li and Shengcheng Zhou. Reactor core transient analysis of an innovative high-level nuclear waste transmuter with metal fuel. International Journal of Energy Research, volume 41 (2017), pages 1322–1334.

 

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Renewable Energy Global Innovations features: Improved solar light stimulated charge separation of g-C3N4 through self-altering acidic treatment

Significance Statement

The process of identifying more efficient as well as green photocatalysts for several environmental remediation and energy conversion processes have received global attention in the last few years. The transformation of the renowned semiconductor catalysts, titanium oxide to the recently synthesized metal free semiconductor, graphitic carbon nitride had exhibited great progress. Recently, this photocatalyst has received significant research attention owing to its distinctive features such as anti-photo corrosion, chemically stable, low cost, and contains most abundant elements. Unfortunately, graphitic carbon nitride suffers from low surface area as well as high recombination rates leading to deprived photocatalytic efficacy.

A number of modifications have been done to enhance the underlying photocatalysis of the bulk graphitic carbon nitride, which include doping with non-metal/metal and other semiconductors and copolymerization.  In addition to enhance the synthesis of new green synthesis photocatalysts, researchers should reconsider on doping modification method. Self-modification of the graphitic carbon nitride is a modification process that has neither been least nor not considered. Recently, graphitic carbon nitride with alkali treatment has developed exhibiting considerable improvement in extending the longevity of the electron hole pairs excited under visible light irradiation. The enhancement in photocatalysis was developed by the decomposing RhB dye.

In addition, porous graphitic carbon nitride with several acidic templates that indicate high performance on degenerating Rhodamine B and phenol has been modified. Unfortunately, this self-altering method of graphitic carbon nitride refinement for solar photocatalysis has not been attempted. Professor Kah Hon Leong and colleagues implemented acid treatment to treat graphitic carbon nitride nanostructured by a direct synthesis method. The proposed treatment enhanced photoactivity of graphitic nitride and was reflected in the removal of recalcitrant organic pollutant, under direct sunlight. Their research work is published in peer-reviewed journal, Applied Surface Science.

The authors prepared photocatalysts that were analyzed via a sustainable photocatalysis method using sunlight as a source of radiation and selecting a poor photosensitive pollutant compound, Bisphenol A. They conducted the experiments under a bright and intense sunlight. In addition, the authors performed dark experiments for about 3 hours to realize adsorption and desorption equilibrium. These experiments were done before solar photocatalysis experiment. Moreover, a control experiment was done in the absence of a photocatalyst.

The authors were able to prepare self-alteration to bulk graphitic carbon nitride via an elementary and direct preparation path with acidic treatment in a bid to extend the longevity of its charge carriers. The researchers recorded a complete removal of the Bisphenol A in 225 minutes by the treated graphitic carbon nitride under intense sunlight as compared to pure graphitic carbon nitride. The improvement could be referenced to the blue shift and delayed the rate of recombination of electrons and holes.

In addition, it influenced the development of active superoxide anion radicals, which were responsible for the photocatalytic activity. The authors then proposed a mechanism of electrons flow that would play a critical role in identifying self-enhancement photocatalysts, which would be stable under intense solar energy.

The outcomes of their study would be important for the increased demand for solar light sensitive photocatalysts that are necessary in satisfying the demands of complicated environmental pollutants particularly in enhancing a sustainable environment.

About The Author

Dr Kah Hon Leong received his Ph.D in Environmental Engineering from University of Malaya in 2015. Currently, he is an Assistant Professor at Universiti Tunku Abdul Rahman, Malaysia. His research focuses on design and synthesis of highly improved solar light driven nanomaterials for sustainable environmental and energy applications.

About The Author

Mr.Ping Feng Lim studied Environmental Engineering from Universiti Tunku Abdul Rahman, Malaysia and graduated in 2016. Currently, he is doing his master degree with Dr Kah Hon Leong on the subject of perovskite photocatalysts for sustainable environmental remediation.

About The Author

Dr. Lan Ching Sim received her Ph.D in Environmental Engineering from University of Malaya in 2015. Currently, she is an Assistant Professor at Universiti Tunku Abdul Rahman. Her research interests include the developing and synthesis of semiconductor, plasmonic and carbon materials photocatalysts for water and energy applications.

About The Author

Mr.Varun Punia is pursuing Bachelor of Technology in Civil Engineering at Indian Institute of Technology Roorkee, India. He has worked at the Environmental Nanotechnology Research Laboratory, Department of Civil Engineering, University of Malaya, Malaysia during his summer internship visit in 2016.

About The Author

Dr. Pichiah Saravanan received doctoral degree in Chemical Engineering from Indian Institute of Technology Guwahati, India. Presently he is Associate Professor in Department of Environmental Science and Engineering, Indian Institute of Technology (ISM) Dhanbad, India and also heading the Environmental Nanotechnology research laboratory.

He was key founder of “Environmental Nanotechnology” research laboratory at Department of Civil Engineering, University of Malaya, Malaysia where he served as Senior Lecturer between 2010 to 2016. He is fascinated in developing nanomaterials for sustainable environmental remediation’s and energy applications.

Reference

Kah Hon Leong, Ping Feng Lim, Lan Ching Sim, Varun Punia, Saravanan Pichiah. Improved solar light stimulated charge separation of g-C₃N₄ through self-altering acidic treatment. Applied Surface Science

 

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Renewable Energy Global Innovations features: Relevant efficiency enhancement of emerging Cu2MnSnS4 thin film solar cells by low temperature annealing

Significance Statement

In the recent years, thin film solar cell manufacturers have suffered from the abrupt decrease of silicon module price. Irrespective of the current efficiency of Cu(In, Ga) Se2 thin film solar cells being very near to the already established silicon-based photovoltaic technology, the low availability of gallium and indium in the Earth’s crust will result in their high cost, and this will definitely limit their future role in terawatt range photovoltaic applications. Therefore, researchers have shifted their attention to low cost materials based on earth abundant elements.

Fortunately, there is an attractive alternative for the preparation of indium and gallium free terawatt-scale chalcogenides. These alternatives depend on I₂-II-IV-VI₄ species, which include copper zin tin sulfide, copper zinc tin selenide and the related sulphur-selenium alloy. Copper manganese tin sulfide, a p-type semiconductor based fully on earth abundant as well as low cost elements, is another member of this group of materials . In view of the fact that manganese is cheaper than zinc, copper manganese tin sulfide can provide W_p cost lower as compared to copper zinc tin sulfide.

Copper manganese tin sulfide that crystalizes into a stannite structure exhibits direct band gap and high absorption coefficient all of which are necessary for photovoltaic applications. Several studies on copper manganese tin sulfide have been mainly based on single crystals and nanocrystals. However, recent studies have been reported on copper manganese tin sulfide thin films for photovoltaic applications.

Alessia Le Donne, Maurizio Acciarri and Simona Binetti at University of Milano-Bicocca in collaboration with Stefano Marchionna and Federico Cernuschi at RSE SpA grew copper manganese tin sulfide thin films through a two-step vacuum process. They grew metal precursor stacks through thermal evaporation and then heat treated them in elemental sulfur vapors. Their research work is published in Solar Energy.

The authors settled for Cu-poor/Mn-rich copper manganese tin sulfide films with Mn/Sn ratio of 1 in a bid to avoid the development of insulating and highly conductive secondary phases. The researchers tested the proposed copper manganese tin sulfide thin films by photoluminescence, Raman, Scanning Electron Microscopy and Energy Dispersive Spectroscopy.

The research team were able to obtain Cu-poor/Mn-rich copper manganese tin sulfide specimens with an acceptable homogeneity of the metal compositional ratios through a stringent control of the manganese evaporation rate. Solar cells manufactured from the films indicated good performance as opposed to a previous study. In view of the advantages of low temperature post-deposition annealing in inert and air atmosphere reported in the literature, the authors investigated the impact of thermal treatments they did between 200 and 275 °C on the copper manganese tin sulfide solar cell efficiency. The analysis encompassed both modification of material attributes and electrical performance.

The best annealing at 225 °C in air for about 40 minutes allowed for significant enhancement of their performance, open circuit voltage 354 mV, short circuit current density 5.8 mA/cm2, 40% fill factor and efficiency of 0.83%. This therefore increased the efficiency of this promising material.

About The Author

Alessia Le Donne got a M.S. degree in Materials Science from the University of Milano-Bicocca in 2001 and in 2004 a Ph.D. in Materials Science from the same Institution. Since 2005 she got several postdoctoral fellowships at the University of Milano-Bicocca and a research fellowship at CNISM (National Interuniversity Consortium for the Physical Sciences of Matter).

She co-authored 63 peer-reviewed papers, 1 book chapter and more than 80 contributions at national or international scientific conferences. Since 2001 she has been involved in several European and national Projects. She regularly serves as peer-reviewer for high impact factor international scientific journals. She is associated editor of the international journals ‘Reviews in Advanced Sciences and Engineering’ and ‘Materials Focus’ and member of the editorial board of ‘Conference Papers in Energy’ and ‘Indian Journal of Materials Science’.

About The Author

Stefano Marchionna got a M.S. degree with honours in Materials Science from the University of Milano-Bicocca in 2003 and a Ph.D. in Materials Science from the same University in 2006. He co-authored 20 peer-reviewed papers and more than 30 communications at national or international scientific conferences. In 2007, he was process engineer at NED Silicon Company (Italy), working on the development of an innovative production line for solar grade silicon. From 2008 to 2013, he was process engineer at Voltasolar Company (Italy), working on the development of low-cost thin films solar cells based on Cu(In,Ga)Se₂ (CIGS). Presently, his research activity at RSE SpA (Italy) is focused on the development of new and alternative materials based on Earth abundant elements both for photovoltaic and energy storage applications.

About The Author

Maurizio Acciarri is Associate Professor in Physics at the Department of Materials Science of the University of Milano-Bicocca. His research activity is mainly addressed to the study of electrical properties of semiconductors for photovoltaic applications. His research in the field of thin films for photovoltaic applications led to an international patent and to the technological transfer of the related Cu(In, Ga)Se₂ growth process to a pilot line. He is co-author of 4 patents. From 2017 he is Director of the Management Committee of the Microscopy Platform of the University of Milano-Bicocca.

Since 2011 he is member of the scientific committee of the Milano-Bicocca Solar Energy Research Center (MIBSOLAR) and since 2013 he is co-director of the center. Since 2014 he is member of the scientific committee and teacher of the Green Energy Management Summer School. Since 2017 he is member of the scientific committee and teacher for the PhD school in Sustainable Human Development. Since 2017 he is member of the editorial board of the international journal ‛Solar Energy’.

About The Author

Federico Cernuschi is the head of the Materials for Energy Research Group at RSE SpA. After completing his studies in physics at the University of Milan, since 1990 he worked on the development and application of advanced non-destructive techniques for the integrity assessment of power plant components and for the physical, thermophysical characterization and wear resistance of coatings and materials for energy applications. He has been responsible for several EU funded research projects. He has published more than 60 papers in international scientific journals. He sits on national and international standards committees focusing on wear and NDE&T and advanced ceramics.

About The Author

Simona Binetti is Associated Professor of Physical Chemistry at University of Milano-Bicocca,  vice director of Milano-Bicocca Solar Energy Research Center (MIBSOLAR), representing UNIMIB in the Joint Program on Photovoltaics of European Energy Research Alliance. Qualified Full Professor in Physical Chemistry. Graduated in Physics, Master in Materials Science and PhD in Chemistry.

Recognized expert in effect of defects on optoelectronic properties of silicon based semiconductors. Involved in 10 European Projects, 9 national about PV, some of them as leader, collaborating in research for private owned companies. She is currently leading 3 projects. Co-author of 120 peer-reviewed publications, 4 book chapters, 4 patents.

Reference

A. Le Donne, S. Marchionna, M. Acciarri, F. Cernuschi, S. Binetti. Relevant efficiency enhancement of emerging Cu₂MnSnS₄ thin film solar cells by low temperature annealing. Solar Energy, volume 149 (2017), pages 125–131.

 

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Renewable Energy Global Innovations features: MnO-Co Composite Modified Ni-SDC Anode for Intermediate Temperature Solid Oxide Fuel Cells

Significance Statement

Fuel cells have the ability to convert chemical energy in fuels to electric energy without the inhibition of the Carnot cycle. Conventional power generating devices are deficient in efficiency, low emissions and the potential for combined heat and power generation, critical features among which the fuel cell vehemently manifests. Solid oxide fuel cells (SOFCs) often operate at high temperatures which contributes to a higher efficiency and power density as compared to other types of fuel cells. More so, the high operating temperatures enable the SOFCs to utilize carbon monoxide as a fuel rather than a poison. SOFCs with Ni-YSZ (yttria-stabilized zirconia) cermet anodes often operate at a higher temperature which translates into higher synthesis cost. Conversely, SOFCs with Ni-SDC (samarium-doped ceria) cermet anodes have exhibited lower operating temperatures and excellent electrochemical performance at intermediate temperatures. Besides, efforts are still needed so as to promote the performance and stability of SOFCs of Ni-SDC anodes in hydrogen and/or methane.

Zhonghua Zhu and his group at The University of Queensland in Australia, proposed studies to enhance the electrochemical performance and/or stability of Ni-SDC anode in hydrogen and/or methane. The authors firstly modified the Ni-SDC anode with manganese oxide and cobalt (MnO-Co) composite in a bid to further promote its performance. The research team begun their empirical work by ball-milling NiO, SDC, dextrin (pore former) and synthesized manganese-cobalt spinel in ethanol for a specific period. They then prepared the anode-supported solid oxide fuel cells. The crystal structures of the synthesized powders and anode powders were characterized by x-ray diffraction. The microstructure of the fabricated solid oxide fuel cells was also examined by scanning electron microscopy.

After the successful fabrication of the Ni-SDC and MnO-Co composite modified Ni-SDC anode-supported SOFCs, the authors observed that when compared with the normal Ni-SDC anodes, the MnO-Co modified Ni-SDC anodes exhibited much higher peak power density and lower polarization resistance in dry hydrogen gas and dry methane gas at all of the temperatures investigated. The modified anode had higher porosity than the original anode. However, the team noted that the stability of MnO-Co modified Ni-SDC anodes was worse than that of Ni-SDC anodes in dry methane due to severer carbon deposition. This research work is now published in Fuel Processing Technology.¹ After that, the authors applied a MnO-Co-SDC internal reforming layer over the Ni-SDC anode and observed significant improvement in its performance and stability in wet methane (3mol% H₂O in methane). They found that the anode started to decline in 150 minutes without the reforming layer, but showed no indication of degradation over 900 minutes due to the methane pre-reforming process after the addition of the MnO-Co-SDC layer at 0.2A/cm² and 650 ^oC and the peak power density was further increased by over 10%. This work has been published in Journal of Materials Chemistry A.² On-going research is being carried out in Prof Zhu’s group.

Reference

• Jie Zhao, Xiaoyong Xu, Wei Zhou, Zhonghua Zhu. MnO-Co composite modified Ni-SDC anode for intermediate temperature solid oxide fuel cells. Fuel Processing Technology, volume 161 (2017) pages 241–247.

Go To Fuel Processing Technology 

 

• Jie Zhao, Xiaoyong Xu, Wei Zhou, Zhonghua Zhu. An in situ formed MnO–Co composite catalyst layer over Ni–Ce₈Sm_0.2O_2-x anodes for direct methane solid oxide fuel cells. Journal of Materials Chemistry A, volume 5 (2017) pages 6494-6503.

 

Go To Journal of Materials Chemistry A  

 

 

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Renewable Energy Global Innovations features: Room temperature hydrogen production from Hg contaminated water, with desirable throughput, and simultaneous Hg-removal

Significance Statement

Fossil fuels produce toxic byproducts on oxidation; hydrogen on the other hand yields water vapor making it a better source of energy. Today industrial hydrogen production primarily adopts an approach using steam reforming of fossil fuels. However carbon monoxide and carbon dioxide are emitted as byproducts of this process. Given this an obvious and simple way of getting hydrogen would be by splitting water, since it is abundant globally. Researchers world over are attempting development of hydrolytic reagents that result in high throughput hydrogen production through splitting of water (also called hydrolysis).

Currently there are numerous methods used for generating hydrogen which include: water decomposition at high temperature, photo electrochemical water splitting, decomposition of water electrochemically, and metal hydrolysis. Heat and electrochemical based water splitting approaches tend to be energy intensive. Light based approaches (i.e photo electrochemical or photochemical) tends to require very pure water, is usually low efficiency, and not yet robust as a process. Metal hydrolysis tends to be expensive and if carefully looked at, is high on carbon footprint (since metal extraction is energy intensive too).

Furthermore post production of hydrogen, its storage, transportation, and handling presents many safety issues. Hence hydrogen fuel though seemingly ideal, is fraught with many engineering challenges. Consequently, there is need to improve techniques of production. It would be ideal to have a process that generates hydrogen on demand; better still if this could be done using dirty water!  Abdul Malek, Edamana Prasad, Subrahmanyam Aryasomayajula, and Tiju Thomas at the Indian Institute of Technology Madras (IITM) in India have developed an approach that does just that. The approach uses nanoscience based ideas to achieve this engineering outcome. – The team developed a novel method with high hydrogen production efficiency using water contaminated with mercury (usually an issue in effluents from several industries, including mines, leather industries etc). The researchers aimed at generating hydrogen through ‘in situ’ formation of nanoaluminum amalgam by simultaneously reducing aluminum (obtained from inexpensive salts) and mercury (present as a contaminant) using a powerful reducing agent. The research work is now published in the journal, International Journal of Hydrogen Energy.

The experiment works well with tap water and would do just as well with dirty water contaminated with mercury. The process cleans up mercury from water, while at the same time producing hydrogen. The process works since the nano-alloy they synthesize using this in situ approach has many galvanic couples on its surface (think of them as ‘nano batteries’ sitting on the nanoparticle surface). In the lab scale,  researchers observed rampant production of hydrogen gas (720 mL per minute of hydrogen for every 0.5 mg of Al salt used). The presence of other contaminants (eg. salts) did not seem to affect the rate nor the amount of hydrogen gas produced. The process scales rather easily with the amount of aluminium salt used; this makes it in principle useful for point of use production of hydrogen (providing a plausible way out for the transportation and storage problem).

Scaling up in the next step, and the team is excited to further their work towards this end. Dr. Tiju Thomas, one of the senior authors said “Getting fuel while purifying water is a very good example of how design thinking and nanoscience can solve some major problems. I particularly enjoy doing this. We, as a team, are excited about the possibility of using this technology is parts of the world wherein mercury is a major contaminant in water. The team behind this story believes that we have just gotten the right lead. Scaling up is the way to go, and partnering with process, water and energy engineers in industry is essential to take this technology to the real world. We have made a good start – the science is there; the next step is to make it available to change makers and innovate along with them”.

In conclusion, Abdul Malek and his co-workers have shown a possible way to overcome some of the major setbacks in current water and hydrogen energy sectors. It offers a possibility for scale up, and improve the efficiency of generating hydrogen using dirty water (mercury contaminated as of now). This method also helps to address the problem of storage and transportation of material, while also cleaning up the mercury from water. The technology lends itself to point of use hydrogen production; the challenges that remains are at the device and systems level. The team envisions their invention to give way to a multi-functional technology.  This procedure is possibly applicable to ocean water and effluents from industries with more complex contaminant composition because of the inability of salts to affect the process. Therefore, more work along these lines are anticipated, and hence development of suitable devices and reactors are the way to go. Everything herein suggests that this novel technique is viable and suitable for adoption. It is important to note here that the technique developed by Abdul Malek and his co-workers is patented (PCT/ IN2017/ 050334) and available for licensing. They are also happy to discuss industry relevant and academic questions with their professional colleagues world over.

Reference

Abdul Malek, Edamana Prasad, Subrahmanyam Aryasomayajula, Tiju Thomas. Chimie douce hydrogen production from Hg contaminated water, with desirable throughput, and simultaneous Hg-removal. International Journal of Hydrogen Energy, Volume 42 (2017) page 15724-15730.

 

Go To International Journal of Hydrogen Energy

 

Malek, A.; Thomas, T.; Prasad, E. Hydrogen generation from waste water via galvanic corrosion of in-situ formed aluminum amalgam, Indian Patent Office, Application No. 201641027502; International application no: PCT/ IN2017/ 050334.

A. Malek, T. Thomas, E. Prasad, Visual and optical sensing of Hg²⁺, Cd²⁺, Cu²⁺, and Pb²⁺ in water and its beneficiation via gettering in nanoamalgam form. ACS Sustain Chem Eng, 4 (2016), pp. 3497-3503.

 

 

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Renewable Energy Global Innovations features: Theoretical Analysis for The Centrifugal Effect On Premixed Flame Speed in A Closed Tube

Significance Statement

The effect of centrifugal acceleration on the mixed flame speed has over time been observed to be significantly important in both theoretical research and engineering application. Recently, empirical investigations on the novel inter-turbine burner engine and the Ramgen engine have shown that they possess significant benefits on performance, since they apply the concept of combustion in high centrifugal fields. Previous studies on centrifugal forces have revealed that high centrifugal acceleration possess significant strengthening effect on combustion. On the contrary, little exists on the adaptation, derivation and harnessing of this power in written academia.

Researchers led by professor Yong Huang at the Collaborative Innovation Center of Advanced Aero-Engine, National Key Laboratory of Science and Technology, School of Energy and Power Engineering, Beihang University described the effect of centrifugal acceleration, specifically high centrifugal acceleration of more than 200 times the gravitational acceleration, on the premixed flame speed in a rotating closed tube. Their main objective was to derive a theoretical predicted correlation which would describe the laminar premixed flame speed in a centrifugal field with the aid of directly solving simplified governing equations on 1-D steady adiabatic flame by theoretical analysis. Their research work is now published in International Journal of Hydrogen Energy.

The research team begun by employing the 1-D steady adiabatic flame model which was fixed. The team then obtained the premixed flame speed in a rotating closed tube after considering the amplification effect of the closed tube on the laminar premixed flame speed. The researchers then, using the predicted correlation, obtained the physical mechanisms of the premixed flame speed in a rotating closed tube.

The authors observed that the flame speed accelerated by the centrifugal force was nearly proportional to the square root of the centrifugal acceleration in the rotating closed tube. The team also noted that the theoretical prediction was also able to revealed that the flame speed in a rotating closed tube was determined by the initial temperature, the critical ignition temperature, the adiabatic flame temperature and the thicknesses of reaction zone. Eventually, the premixed flame speed in a rotating closed tube was seen to increase nearly linearly with the increasing of the initial temperature or square root of the thicknesses of reaction zone, or with decreasing of the critical ignition temperature or the adiabatic flame temperature.

Herein, a theoretical analysis to study the effect of centrifugal acceleration, especially high centrifugal acceleration, that is, more than 200 times the gravitational acceleration of earth, on the premixed flame speed has been successfully presented. More importantly, a theoretical predicted correlation has been proposed to describe the premixed flame speed in a rotating closed tube. The results of the theoretical prediction have been seen to agree well with the empirical data obtained by Lewis & Smith. The result of the study verifies that the flame speed accelerated by the centrifugal force is nearly proportional to the square root of the centrifugal acceleration.

About The Author

Dr. Yong Huang is the chief professor in the Department of thermal power engineering, School of Energy and Power Engineering, Beihang University, Beijing, China. He was granted Bachelor Degree from Tsinghua University in 1985. Then, he obtained Master Degree and Doctoral Degree in Beihang University. He did postdoctoral research in Hong Kong University of Science and Technology.

He is one of the top experts in the field of gas turbine combustion in China. In the past years, he has won the second prize of science & technology improvement by Ministry of Aviation Industry of PRC(1993), the third prize of science & technology improvement by Ministry of Aviation Industry of PRC(1993), the second prize of science & technology improvement by Ministry of National Defence(2004).

His main research interests include the mechanism and prediction of ignition and lean blowout in gas turbine combustors, mechanism of atomization and design of atomizers, performance prediction of low pollution combustors, flow field analysis in combustors, and multipoint lean direct injection combustors, etc.

He proposed the concept of Flame Volume(FV) model to improve the prediction of lean blowout limit derived by Lefebvre. This is an important breakthrough for gas turbine combustors in recent years. And he proposed the concept of flame mixing time (FMT) to estimate the NOx formation and obtain good agreement with the experimental data done by NASA that was ever wrongly predicted by other methods. Besides, he firstly proposed the concept of loss of rotational kinetic energy in pressure swirl atomizers due to liquid viscosity to predict the spray cone angle of pressure swirl atomizers. His course, combustion and combustor, is one of excellent courses in Beihang University. He has published more than 150 academic papers.

Contact: yhuang@buaa.edu.cn

About The Author

Dr. Lei Sun is a PhD candidate in the Department of thermal power engineering, School of Energy and Power Engineering, Beihang University, Beijing, China. He was granted Bachelor Degree from Beihang University in 2012. He was a visiting researcher in Hokkaido University, Japan in 2016.

He is experienced in mathematical modeling and theoretical analyses for physical phenomena. He has won the first prize of National Mathematics Competition for College Students(2011), the second prize of National Physics Competition for College Students(2010), the third prize in the Zhou Pei-Yuan Mechanics Competition for College Students(2011), etc. His research topics include the mechanism and prediction of lean blowout in gas turbine combustors, multipoint lean direct injection combustors, and mechanism of atomization, etc. He has published 8 academic papers.

Contact: sunlei1988@buaa.edu.cn

About The Author

Ms. Yingyi Ji is an engineer of gas turbine engine in Aero Engine Corporation of China. She was granted Bachelor Degree from Beihang University in 2013. She received her master degree in Aeronautical Engineering from Beihang University in 2016, researching on the centrifugal effect on premixed flame speed and the optimization design on diffuser of lean direct injection combustor.

Her recent research includes heat transfer of perforated plate, Oxygen-deficient Combustion in low speed gas flow.

Contact: jiyingyi0319@sina.com

Reference

Lei Sun, Yong Huang, Yingyi Ji. Theoretical analysis for the centrifugal effect on premixed flame speed in a closed tube. International Journal of Hydrogen Energy, volume 42(2017) pages 18658 – 18667.

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Renewable Energy Global Innovations features: Molecularly Imprinted Polymer Enables High-Efficiency Recognition and Trapping Lithium Polysulfides for Stable Lithium Sulfur Battery

Significance Statement

Molecularly imprinted polymers have in recent times been attracting widespread interest especially arising from their application in the development of tools for organic synthesis as a result of their high specificity, easy availability, stability and low cost. These synthetic polymers are fabricated by polymerizing polymerizable reagents in the presence of a template. More so, these molecularly imprinted polymers have the capability to selectively reorganize and bind target molecules with tailor made molecular recognition binding sites. With such binding capabilities, molecularly imprinted polymers have been widely applied in catalysis, analytical chemistry, water treatment, sensors and biochemistry field.

However, their potential can still be tapped by constructing different binding sites which would in turn yield new applications. Consequently, the mutual demand for clean energy from modern industries inclusive of military power supplies, civil transportation and stationary storage have placed urgent demands on the energy density of the battery. Lithium-sulfur batteries have been considered promising for powering portable electronics because they have an overwhelming advantage in energy density.

Prof. Chenglin Yan and colleagues from Soochow University in China proposed a breakthrough study on the adaptability of molecularly imprinted polymers to enable high efficiency recognition and trapping of lithium polysulfides for the development of stable lithium-sulfur battery. The researchers aimed at exploiting the ability of the molecularly imprinted polymers to recognize and target specific molecules. Their research work is now published in Nano Letters.

The researchers commenced their empirical procedure by preparing molecularly imprinted polymers with Lithium-Sulphur recognition characteristics by polymerization of acrylamide monomer molecular with tetraglyme catholyte as the target template. Polymerization by initiation at 70⁰C with azodiisobutyronitrile as the initiator was then effected. Eventually, the removal of template molecule by anhydrous dimethylformamide washing and cyclic voltammetry scans, that left featured binding sites in the polymer matrix was done.

The research team observed that the approached they used, permitted them achieve a high capacity retention of over 82% after just 400 cycles at one coulomb. They also noted that the UV/vis spectroscopy revealed low concentrations of tetraglyme catholyte in the electrolyte indicating that the molecularly imprinted polymers matrix has excellent ionic sieving ability to tetraglyme catholyte during electrochemical cycle. More so, the visual characterization gave direct evidence on the affinity and absorbability of molecularly imprinted polymers to tetraglyme catholyte, which was theoretically confirmed by density functional theory calculations.

Herein, a new strategy of using molecularly imprinted polymers as recognition sites for polysulfides in Lithium-Sulphur battery system so as to trap long chain polysulfides, has been brought forward. Acrylamide and tetraglyme catholyte molecule have been employed as functional monomer and template, respectively, for the construction of molecularly imprinted polymers material, which can constraint tetraglyme catholyte in the molecularly imprinted polymers matrix by rebinding the target molecules. Undoubtedly, the original design demonstrated here opens a new direction of the electrochemical application of molecularly imprinted polymers materials in Lithium−Sulphur batteries.

About The Author

Chenglin Yan is a full professor at Soochow University and executive director of key laboratory of advanced carbon materials and wearable energy technology in Suzhou, China. He received his PhD from Dalian University of Technology in 2008. In 2011, he became a staff scientist and a group leader at the Institute for Integrative Nanoscience at the Leibniz Institute in Dresden. In 2013, the IFW-Dresden awarded Dr Chenglin Yan the IIN Research Prize 2013 for his group’s research work. He received the Thousand Young Talents Award from the Chinese Thousand Talents Program in 2014.

Reference

Jie Liu, Tao Qian, Mengfan Wang, Xuejun Liu, Na Xu, Yizhou You, and Chenglin Yan. Molecularly Imprinted Polymer Enables High-Efficiency Recognition and Trapping Lithium Polysulfides for Stable Lithium Sulfur Battery. Nano letters 2017, volume 17, pages 5064−5070.

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Renewable Energy Global Innovations features: Cloud Energy Storage for Residential and Small Commercial Consumers: A Business Case Study

Significance Statement

Both industry and academia have with time come to recognize the significance and potential of energy storage as a prospective resource that can help create a balance between generation and load in power systems. Presently, the world is migrating towards renewable resources with variable renewable energy sources such as wind and photovoltaics. Maintaining the stability of a power system requires real-time balancing of the energy that is consumed and produced. Recent trends are focusing on utilizing distributed energy storage systems by both small residential and commercial users so as to integrate variable renewable energy and reduce electricity bill. Cost, policy, and control efficiency limit the profitability of distributed energy systems and hinders the incentive of both small residential and commercial consumers to purchase the distributed energy storage systems. Among recent power grid and internet technological advances, resource sharing make possible a better utilization of distributed energy systems resources.

Tsinghua University and University of Washington researchers developed a novel way of using energy storage – cloud energy storage – a grid-based storage service that enables ubiquitous and on-demand access to a shared pool of grid-scale energy storage resources. The team aimed at describing how this state of the art technology would be realized and how it is capable of providing energy storage services at substantially lower cost. They also described the cloud energy storage enabling technique that supports both the needs of residential distributed energy systems and the optimal operation of storage resources. Their research work is now published in Applied Energy.

Chongqing Kang and colleagues commenced by conducting empirical works where by, firstly, they proposed the concept of cloud energy storage which utilized central energy storage facilities to provide distributed storage services to residential and small commercial users. They then developed and described the architecture, enabling technologies and operation mechanisms that would facilitate the cloud energy storage. The team then designed the business model of cloud energy storage and demonstrated its profitability using real life residential load and electricity data.

The authors observed that cloud energy storage users can use their cloud batteries just like real energy storage devices. Based on the case study on actual residence load data and electricity price, the team noted that social benefits including, the minimal influence on the percentages of social welfare improved by cloud energy storage due to lower unit price as a result of energy storage. In totality, it was seen that cloud energy storage was more economical than distributed energy systems since the economies of scale has a significant influence on the economy of cloud energy storage.

Chongqing Kang and colleagues successfully described novel concept-cloud energy storage. This new service has the potential to provide the same services as the presently used distributed energy system does, but now at a lower social cost. Its future is so great in that it has the potential to, one day, gather fragments of energy storage resources such as electric vehicles, uninterrupted power supplies and residential distributed batteries. More so, the cloud energy storage business model can presently be merged into some current business models as value-added services.

About The Author

Jingkun Liu is currently a public official in the government of Shuyang Town, Xianghe County, Hebei Province, China. He received his Bachelor’s degrees of Electrical Engineering and Economics from Tsinghua University in 2012 and Peking University in 2013, respectively. He received his Ph.D of Electrical Engineering from Tsinghua University in 2017. He was a visiting student in the University of Washington, Seattle from Sep. 2015 to Sep. 2016.

 His research interests focus on energy storage in power system and power system reliability.

About The Author

Ning Zhang is an associate professor in the Department of Electrical Engineering, Tsinghua University. He got his B.Sc. degree from Tsinghua University, Beijing, China in 2007. He got his Ph.D in electrical engineering with Excellent Doctoral Thesis Award and Excellent Graduate Student Award from Tsinghua University in 2012. After he completed two-year research as a post doctor, he started working in Tsinghua University as a Lecturer in 2014. He was a research associate in The University of Manchester from Oct. 2010 to Jul. 2011 and a research assistant in Harvard University from Dec. 2013 to Mar 2014. He was awarded Yong Elite Scientists Sponsorship Program by Chinese Association of Science and Technology in 2016. His paper is awarded one hundred most influential papers and top articles in outstanding S&T journal of China.

 His research interests include multiple energy system, power system planning and operation with renewable energy (wind power photovoltaic, concentrated solar power).

About The Author

Chongqing Kang is a full professor and the Chairman of Executive Committee of Department of Electrical Engineering. He holds Bachelor’s degrees of both Electrical Power Engineering and Environmental Engineering in 1993, and a Ph.D in Electrical Power Engineering from Tsinghua University in 1997. He has been appointed Professor of Electrical Engineering Department of Tsinghua University since 2005. From 2011 to 2014 he was the Director of Centre for Teaching Excellence, Tsinghua Univ.

He is the recipient of the National Science Fund for Distinguished Young Scholars. He is Fellow of IEEE and IET. He is the senior member of CSEE. He has been on the editorial board of 5 international journals including IEEE Transactions on Power Systems and Electric Power Systems Research and 6 Chinese journals indexed by EI. He won the second prize of National Teaching Achievement Award in 2014. He and his team was granted the Institute Prize in Global Energy Forecasting Competition in 2014. He was granted one gold award and one silver award in the 44th International Exhibition of Inventions in Geneva in 2016.

 His research interests include power system planning, power system operation, renewable energy, low carbon electricity technology, load forecasting and electric market.

About The Author

Daniel S. Kirschen was appointed Close Professor of Electrical Engineering in 2011. From 1994 to 2010, he was Professor of Electrical Energy Systems and Head of the Electrical Energy and Power Systems research group at the University of Manchester in the UK. Prior to joining the academic world, he worked for Control Data Corporation and Siemens-Empros on the development of advanced application software for electric utilities.

His research interests include Integration of renewable energy sources in the grid, power system operation, power system economics, and resilience of the grid to natural disasters.

About The Author

Qing Xia is now a professor at Tsinghua University, Beijing, China. He received his Ph.D. degree from the Department of Electrical Engineering at Tsinghua University in 1989.

 His research interests are mainly power economics, power markets, power system expansion planning, power system reliability, power system load forecasting, and smart grids.

Reference

Jingkun Liu, Ning Zhang, Chongqing Kang, Daniel Kirschen, Qing Xia. Cloud energy storage for residential and small commercial consumers: A business case study. Applied Energy volume 188 (2017) pages 226–236

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Renewable Energy Global Innovations features: Copper nanowire/multi-walled carbon nanotube composites as all-nanowire flexible electrode for fast-charging/discharging lithium-ion battery

Significance Statement

With the rapid evolution of autonomous vehicles, electric vehicles are anticipated to continue to grow rapidly. The electric vehicles offer many benefits such as zero emissions, less noise and vibrations, and are operated by simple electric motors with energy conversion in the range of 80-90%. Electric vehicles also have superior energy resilience since they can be charged using a number of energy sources such as renewable energy, conventional power-plant energy, and regenerative braking energy.

Unfortunately, the electric vehicles suffer some limitations such as cost, safety, mileage, limited lifespan, long charging time, and lack of grid for charging. These problems have led to the development of power systems with Lithium-ion batteries. In a bid to fix cost and mileage issues, the energy density of lithium-ion batteries must be increased, and the only way to improve the energy density would be to come up with new active materials with high theoretical capacity for anodes and cathodes.

Although high capacity materials can be applied to the Li-ion batteries, Li-ion batteries would still take long time to charge owing to their low power densities. Unfortunately, even the recently developed fast chargers with pulse power cannot overcome energy-density fading in the course of high-current charge/discharge reference to the limitation in the energy-conversion reaction of Li-ion batteries.

Researchers led by Professor Youn Sang Kim at Seoul National University, Republic of Korea, proposed a novel all-nanowire electrode structure for fast-charging-discharging Li-ion batteries implementing copper nanowires and multi-walled carbon nanotubes without binders or even conductive agents. Theoretically, the multi-walled carbon nanotubes as the representative one-dimensional carbon-based nanostructure provided fast channels for the effective transport of both electrons as well as ions for Li-ion batteries owing to their unique features that had high aspect ratio as well as large surface area. However, the large voltage range between charging and discharging is normally limited the multi-walled carbon nanotubes to be used for active materials in full cells, due to their morphology and resistivity. The authors firstly overcame this limitation of multi-walled carbon nanotubes, and their work is published in peer-reviewed journal, Nano Research.

The authors fabricated a lightweight 3-dimensional composite anode for a fast charging-discharging Li-ion battery implementing two of 1-dimensional nanomaterials, which were copper nanowires and multi-walled carbon nanotubes. Reference to superior electrical conductivity, large surface areas, and high aspect ratio of these materials, the copper nanowire-multi walled carbon nanotubes composite with 3-dimensional structure provided several advantages concerning transport channels of ions and electrons.

The copper nanowires applied as the current collector and multi-walled carbon nanotubes applied as the active materials provided a number of benefits for enhancing the Li-ion battery performances. These included efficient ion diffusion, thick electrode formation, fast electron transport, and flexible cell design. As an advanced binder-free anode, the proposed composite film with tunable thickness indicated a significant low sheet resistance and internal cell resistance. The copper nanowires network with 3-dimensional structure functioned as a rigid framework connected to the multi-walled carbon nanotubes. They prevented the shrinkage and expansion of the multi-walled carbon nanotubes owing to swelling and aggregation, and minimized the effects of volume change of the carbon nanotubes during the charging-discharging process.

Both the full and half-cells of the Li-ion batteries with 3D-composite film anode indicated high specific capacities and Coulombic efficiencies even at high currents. The authors were able to overcome, for the first time, the limitations of carbon nanotubes as anode materials for fast charging and discharging Li-ion batteries by implementing copper nanowires, and the proposed anode can be used in flexible Li-ion batteries. This new development could result in the development of ultrafast chargeable Li-ion batteries for electric vehicles.

About The Author

Zhenxing Yin completed his Bachelor’s studies at Changchun University of Technologies (China) in 2012. Then, he received his Master’s degree at Seoul National University (Republic of Korea) in 2014, and is currently a Ph.D. candidate at Graduate School of Convergence Science and Technology, Seoul National University. His research interests mainly focus on copper nanowire synthesis and applications.

About The Author

Prof. Jeeyoung Yoo is the research professor in Graduate School of Convergence Science and Technology, Seoul National University at Seoul, Korea. A graduate of Chung-Ang University, she holds a Bachelor of Chemical Engineering, Master of Chemical Engineering, and PhD in Chemical Engineering, specializing in electrochemical engineering. And she is an expert in energy storage materials and device-related research and development.

About The Author

Prof. Youn Sang Kim is the Professor in Graduate School of Convergence Science and Technology, Seoul National University at Seoul, Korea. He received Ph.D. in the Department of Chemical Engineering from Seoul National University at Seoul, Korea in 2002 and then worked for two years as a postdoctoral fellow in Massachusetts Institute of Technology, USA. His current research interests are concentrated on interface engineering for novel devices such as energy harvesting devices, oxide or hybrid TFTs, oxide diodes and printing electronics.

Reference

Zhenxing Yin, Sanghun Cho, Duck-Jae You, Yong-keon Ahn, Jeeyoung Yoo, and Youn Sang Kim. Copper nanowire/multi-walled carbon nanotube composites as all-nanowire flexible electrode for fast-charging/discharging lithium-ion battery. Nano Res. 2017, DOI: 10.1007/s12274-017-1686-0.

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Renewable Energy Global Innovations features: CH3NH3PbI3 Converted from Reactive Magnetron Sputtered PbO for Large Area Perovskite Solar Cells

Significance Statement

Exponential growth in both interest and attention paid to the organic-inorganic metal halide perovskites materials have spiked undeniable concern of late. The outstanding properties possessed by these materials carry all the credit. These properties, including: long exciton diffusion length, strong absorption coefficients, low cost, ease of Synthesis and environmental-friendliness have led to great advancement in perovskite solar cells such as improving the power conversion efficiency from around ten percent in the early years of this decade to about twenty percent at present. Recent studies have shown that the quality and morphology of the perovskite films are crucial to its photoelectric properties and that they directly influence the performance of the resultant perovskite solar cells. Even though several deposition techniques have been proposed for synthesis of the perovskite light-absorption layers, great difficulties are still being encountered in the bid to fabricate perovskite films with both satisfactory coverage and uniformity over a large area.

Researchers led by Professor Meicheng Li at the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources in North China Electric Power University developed a novel process route based on direct current reactive magnetron sputtering in the preparation of the CH₃NH₃PbI₃ film. They aimed at presenting a complete approach for the fabrication of large area perovskites solar cells with the advantages of easy control, economical and requiring less use of toxic reagents but with diverse potential applications. Their research work is now published in Solar Energy Materials & Solar Cells.

The research team began by fabricating the lead oxide film on an FTO-glass substrate coated with a nanocrystalline rutile titania by using a pure metallic lead target in an argon-oxygen mixture. They then converted the prepared lead oxide film to CH₃NH₃PbI₃ through the sequential reactions setup in isopropanol solution of CH₃NH₃I. Eventually, the research team fabricated solar cells of a complex structure that employed nanocrystalline rutile titania as the contact layer of the photovoltaic devices.

The authors were able to observe that the as-prepared perovskite film exhibited a surface morphology of high uniformity and excellent coverage over a large scale. Also the crystal grains were seen to reach the size of up to 600 nm, which is beneficial to extract photo-generated electrons more effectively and prepare the perovskites solar cells at low temperature.

The new approach employed in their study is technically spin-coating-free for the formation of large area CH₃NH₃PbI₃ film and exhibits advantages ranging from easy process control, economical all the way to less use of toxic reagents. Of crucial importance, it is expected that this novel technique will be applied for the synthesis of perovskites solar cells or other thin-film devices and thus entails potential applications and practical significance.

The schematic illustration of CH3NH3PbI3 formation (on NRT-coated FTO glass substrate) through the sputtered PbO.

The top-view SEM of CH3NH3PbI3 converted from the sputtered PbO, where the insertions are the corresponding one with high magnification.

About The Author

Zhirong Zhang is a Ph.D candidate, who studied at the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources in North China Electric Power University, under the supervision of Prof. Meicheng Li. He received his B.S. degree majored in Radio Physics, from Lanzhou University, in 2008. His research interests include development of thin film solar cells and the design & application of photovoltaic system. He has been working on perovskite solar cells since the year of 2013.

About The Author

Prof. Meicheng Li is the Director of New Energy Materials and PV Technology Center, and the Vice Dean of the School of Renewable Energy, North China Electric Power University. He obtained his PhD at Harbin Institute of Technology in 2001. He worked in University of Cambridge as Research Fellow from 2004 to 2006. He won the Excellent Talents in the New Century by the ministry of education in 2006. His current research topic is the New Energy Materials and Devices, such as perovskite solar cells, lithium ion battery system. Till now, he contributed more than 200 journal articles and performed the review services for about 80 SCI journals. He got almost more than 10 items of awards for the science and technology success. He served more than 20 academic conferences as the chair, track co-chair or session chair. He is an executive fellow of the China Energy Society, fellow of Chinese Society for Optical Engineering.

Website , Research Gate.

Reference

Zhirong Zhang, Meicheng Li, Wenjian Liu, Xiaopeng Yue, Peng Cui, Dong Wei. CH₃NH₃PbI₃ converted from reactive magnetron sputtered lead oxide (PbO) for large area perovskite solar cells. Solar Energy Materials & Solar Cells, volume 163 (2017) pages 250–254.

 

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Renewable Energy Global Innovations features: Titanium Oxide Nanofibers Decorated Nickel-Rich Cathodes as High Performance Electrodes in Lithium Ion Batteries

Significance Statement

Layered cathode active materials partially-substituted cobalt with transition metals and spinel active materials have been received more attention due to their cost effectiveness as compared to lithium cobaltate. Scholars have realized with time that the spinel cathode active materials are safe with limited specific capacities while layered cathode active materials possess high specific capacity with safety issues. Presently, layered cathode active materials are more preferred as cathode materials for lithium ion batteries, where nickel-rich layered cathode active materials are front runners except for safety issues, due to their high capacity. To overcome the safety issue challenge, measures, such as the substitution of the transition metal ions with other metal counter ions and the modification of the surface by means of coating with metal oxides, have been put in place.

Nanoparticle coatings on layered cathode active materials have been known to suppress the thermal reaction between the electrode and electrolyte. It has thus been seen necessary to coat or decorate the surface of the cathode since probable exothermic reaction starts from the cathode surface when the electrolyte is decomposed. Extensive studies have been performed on coating materials that inhibit this reaction but little exists about nanofibers-based metal oxides decorated on lithium nickel cobalt aluminum oxide cathode active materials.

Professor Chang Woo Lee and colleagues from the Department of Chemical Engineering, College of Engineering, Kyung Hee University, Yongin, Gyeonggi, South Korea, proposed a study to modify the surface of lithium nickel cobalt aluminum oxide particles by decorating them with titania nanofibers. They aimed at comparatively studying, with the novel lithium nickel cobalt aluminum oxide, the various quantities of titania nanofibers decorated over lithium nickel cobalt aluminum oxide (LNCA). Their research work is now published in the peer-reviewed journal, Journal of Industrial and Engineering Chemistry.

The researchers commenced their empirical procedure by obtaining titania nanofibers precursor through electrospinning a sol-gel polymeric solution. They then obtained the LNCA precursor. The titania nanofibers precursors were split at 0.5 wt%, 1 wt% and 1.5 wt% before addition of the LNCA precursor powders. The precursor powder mixture was then sintered at 465^oC for three hours and then calcined at 850^oC for five hours in air. The team then conducted an X-ray photoelectron spectroscopic analysis to investigate the chemical composition of the cycled electrode surface. The team eventually obtained cathode samples and used them to conduct differential scanning calorimetry scans.

The authors also observed that the increase of titania nanofibers decoration over 1wt% ratio showed negative effect during the electrochemical process, as observed using electrochemical impedance spectra for the 1.5wt% titania nanofibers-decorated LNCA. Hence usage of titania nanofibers more than 1wt% was excluded from detailed investigation. The surface modification of LNCA electrodes by 1wt% titania nanofibers decoration greatly increased the cycleability, capacity, and thermal stability of lithium ion batteries at room temperature as well as at elevated temperature. Among titania nanofibers decorated LNCAs, the 1wt% titania nanofibers -decorated LNCA cathode had shown better capacity retention of 89.2% and 81.9% at room and elevated temperature, respectively.

The results of their study second the suggestion of the applicability of titania nanofibers as surface modifiers in order to enhance the electrochemical and thermal properties of lithium ion batteries. Moreover, it has been seen that the capability of the titania nanofibers-decorated LNCA was enhanced compared to that of the pristine LNCA. The onset temperature of thermal decomposition is also shifted towards higher temperature for titania nanofibers-decorated LNCA electrodes than pristine LNCA electrodes.

About The Author

Professor Chang Woo Lee is currently serving in the Department of Chemical Engineering and also Director of Center for the SMART Energy Platform at Kyung Hee University, S. Korea. He joined Kyung Hee University in 2006, having received B.S. and M.S. degrees in 1994 and 1996, respectively, at Kyung Hee University, S. Korea and a Ph.D. at the Illinois Institute of Technology, USA in 2003, both in the field of Chemical Engineering. Prof. Lee has also worked as a Senior Researcher at Korea Electrotechnology Research Institute (KERI) since he obtained Ph.D. degree. He was appointed as a Visiting Scholar in the Materials Department, College of Engineering and Applied Science, at the University of Wisconsin-Milwaukee, for the 2012-2015 academic year.

Prof. Lee’s research is focused on electrochemical energy storage & conversion and seek to synthesize energy materials in metallic micro- and/or nanostructures for the purpose of improving electrochemical properties in the area of batteries, supercapacitors, and fuel cells.

About The Author

Mr. Kijae Kim is currently a Ph.D. candidate at the Department of Chemical System Engineering in The University of Tokyo, Japan. He received his B.S. and M.S. degrees in the Department of Chemical Engineering at Kyung Hee University, S. Korea. He has studied synthesis and analysis of electrode materials for energy storage devices for the M.S. under the supervision of Prof. Chang Woo Lee. He has published several scientific papers and received the Best Poster Award from Korean Battery Society and bachelor graduation with honors.

About The Author

Dr. K. Prasanna obtained his B.S. and M.S. degrees from Bharathidasan University and Anna University in India, respectively. He then joined as assistant professor in the Department of Biotechnology at Vinayaka Missions University, Salem. He joined as a Ph.D. student under Professor Chang Woo Lee in the Department of Chemical Engineering at Kyung Hee University, S. Korea in September, 2011 and received his Ph.D. degree in Aug, 2015. He then continued his career as a postdoctoral fellow at Electrochemical Energy Storage and Conversion Laboratory, Kyung Hee University for two years. Currently he is working as a postdoctoral fellow in Technical University of Denmark, under the H.C. Ørsted Postdoc programme, co-funded by Marie Skłodowska-Curie Actions. His recent research interests include supercapacitors, Li-ion batteries, Mg-ion batteries, and Metal-air batteries.

About The Author

Dr. T. Subburaj received his Ph.D. at Kyung Hee University, South Korea in 2015 under the supervision of Prof. Chang Woo Lee in the Department of Chemical Engineering and he received his M.S. degree from the Department of Chemical Engineering, Anna University, Chennai, India in 2010. Currently, he works with Prof. Chung-Hsin Lu as a MoST Postdoctoral Scholar at National Taiwan University, Taiwan. His research interests focus on synthesis and applications of nanostructured and hybrid materials for electrochemical energy storage and conversion, including rechargeable batteries, electrochemical capacitors, and solar cells.

About The Author

Dr. Yong Nam Jo received his M.S. and Ph.D. degrees in Department of Chemical Engineering from Kyung Hee University, S. Korea in 2013 and 2017, respectively, under the supervision of Prof. Chang Woo Lee. He received Best Thesis Award for the Ph.D. from the President of Kyung Hee University and also several Best Poster and Outstanding Paper Awards from domestic and international conferences. He is currently working as a postdoctoral fellow at the Center for SMART Energy Platform at Kyung Hee University. His current research is focused on enhancement of materials for energy storage and conversion with Li-ion batteries and metal-air batteries.

Reference

Subburaj, Yong Nam Jo, K. Prasanna, Ki Jae Kim, Chang Woo Lee. Titanium oxide nanofibers decorated nickel-rich cathodes as high performance electrodes in lithium ion batteries. Journal of Industrial and Engineering Chemistry, volume 51 (2017) pages 223–228.

 

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