Renewable Energy Global Innovations features: Nano “Zylon” Fiber Makes Battery Safer

Significance Statement

Safe and powerful lithium based batteries are important for various technologies, such as electric vehicles, smartphones, and laptops. One of the biggest problems facing this industry is the growth of dendrites sprout from the surfaces of lithium electrodes over the course of several charge/discharge cycles, particularly at a fast rate. The dendrites can spread across the electrolytes and reach the other electrodes, making the batteries short-circuited. The consequent high electric currents may lead the batteries to rapidly overheat and even catch fire.

Researchers in Beijing Institute of Technology, China, and Northwestern University, USA have developed a new type of advanced battery separators to solve this problem. These separators are made of lightweight and ultrastrong materials typically used in Zylon, a commercial microfiber with mechanical properties higher than the well-known Kevlar.

The process for making this advanced battery separators is quite scalable. Zylon microfibers are exfoliated into nanofibers through a special processing step, and then blade-cast into thin and nanoporous membranes. These membranes have a combination of high strength, low ionic resistance, and high heat tolerance, making them exceptionally good separators for preventing dendrite growth in lithium batteries.

The new separators have several advantages in comparison to one of the current state-of-the-art battery separators, Celgard 2400. The electrodes in batteries with the Celgard 2400 show mossy surfaces as a result of dendritic lithium growth, whereas electrode surfaces with the new separator membranes still remain smooth even after 700 hours. The suppression of dendrite formation results in good performance of batteries, including higher long-term stability and higher efficiencies.  As the materials in the separators are highly heat-tolerant, these separators can be used for batteries required in high-temperature environment.

As a comparison, the typical Celgard 2400 separators begin to melt at about 125 °C and make the batteries unusable, while batteries with the new advanced separators can continue to operate up to 185 °C, upon which the electrolytes decompose. In addition, these separators may be applied in other energy storage systems in which dendrite growth is a problem.  

About The Author

Dr. Xiaoming Hao graduated from Beijing Institute of Technology in 2015, and now work at The National Center for Nanoscience and Technology, Chinese Academy of Sciences as a postdoctoral fellow.  

About The Author

Dr. Jian Zhu is currently a postdoctoral fellow at the Northwestern University, USA. He is interested in the assembly of nanomaterials, and their applications in advanced structural and electrical materials.  

About The Author

Dr. Zhenhua Wang worked at Beijing Institute of Technology as an associate professor and vice dean of chemistry and chemical engineering college. His research interests mainly focus on solid oxide fuel cells and various lithium batteries.  

About The Author

Professor Kening Sun is the Cheung Kong Scholar Chair Professor at Beijing Institute of Technology. His research interests mainly focus on fundamental electrochemistry, advanced energy materials, solid oxide fuel cells and various lithium batteries.

Journal Reference

Xiaoming Hao¹ , Jian Zhu^*3, Xiong Jiang¹, Haitao Wu¹, Jinshuo Qiao¹, Wang Sun¹, Zhenhua Wang^*1,2, Kening Sun^*1,2. Ultrastrong Polyoxyzole Nanofiber Membranes for Dendrite-Proof and Heat-Resistant Battery Separators. Nano Lett., 2016, 16 (5), pp 2981–2987.

Show Affiliations

1. Beijing Key Laboratory for Chemical Power Source and Green Catalysis, School of Chemical Engineering and Environment,
2. Collaborative Innovation Center of Electric Vehicles in Beijing, Beijing Institute of Technology, No. 5 Zhongguancun South Avenue, Haidian District, Beijng, 100081, P. R. China
3.  Department of Materials Science and Engineering, Northwestern University, 2200 Campus Drive, Evanston, Illinois 60208, United States

 

 

 

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