Significance Statement
Researchers have been facing the challenge of increasing better performance of storage devices in order to meet up with the required demands for the future. Their investigations are mostly based on obtaining the most appropriate electrode materials.
In view of having a better performance of lithium-ion batteries, electrode materials such as anode and cathode are major factors that need to be considered as they contribute effectively to enhancement of energy density of these batteries. Required features for anode materials include high capacity, high cyclability, high coulombic efficiencyand the excellent rate performance amongst others.
From previous research, silicon when used as anode materials shows certain attractive attributes. However, their poor cyclability remains a bane to their advantages as it often leads to pulverization due to the huge volume change over repeated cycles.
Researchers later discovered that silicon nanoparticles when used as an anode in lithium-ion batteries exhibits high cyclability, but the morphological bindings of these nanoparticles and their connection towards current collector during lithiation-delithiation process still remains a challenge that needs to be overcome.
A new research led by Professor Jinbao Zhao at Xiamen University in China involved the fabrication of silicon-multi-walled carbon nanotubes-carbon (Si- MWNTS-C) microspheres via ball milling and spray drying method by a carbonization process for the latter in view of analyzing their performance towards enhancement of lithium-ion batteries. The work was published in Journal of Materials Science.
They characterized the features of the fabricated silicon-multi-walled carbon nanotubes-carbon with the aid of scanning electron microscopy, transmission electron and x-ray diffraction coupled with electrochemical measurements with the aid of cyclic voltammetry and electrochemical impedance spectra.
Results from the characterization techniques confirmed carbon as the effective conductive agent between silicon nanoparticles and the multi-wall carbon nanotubes microspheres which provides a 3D conductive network thereby resulting to a high electrical conductivity. They also possessed good porosity which makes them adapt to large changes in volume during discharge-charge process.
At a current density of 0.2 Ag-1, the authors observed while using the ball-milling method that the specific capacity of the silicon-multi-walled carbon nanotubes-carbon to be 1100 m Ah g-1 while also possessing high capacity retention of about 90% after 60 cycles. This was not the case for the ordinary silicon nanoparticles as it showed drastic reduction after 50 cycles. Further results also confirmed an enhanced columbic efficiency which was also found when using the spray drying method. The silicon-multi-walled carbon nanotubes-carbon also possessed high rate performance and reversibility when observed at current densities range from 0.1 to 0.6 A g-1.
In order to test the performance of the silicon-multi-walled carbon nanotubes-carbon in a lithium-ion battery, LiCoO2 was used as the cathode. A high cyclic stability was still observed and no morphological changes were observed when viewed after 100 cycles except for growth spherical particles.
The authors of the study provided an improved performance for silicon nanoparticles with the aid of multi-walled carbon conductor link, which shows a potential improvement for lithium-ion batteries.
Reference
Zhang, Y., Li, K., Ji, P., Chen, D., Zeng, j., Sun, Y., Zhang, P., Zhao, J. Silicon-Multi-Walled Carbon Nanotubes-Carbon Microspherical Composite as High-Performance Anode for Lithium-Ion Batteries, Journal of Materials Science 52 (2017) 3630-3641.
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