Our institute's team led by Associate Professor Zheng Gaofeng has made significant progress in the development of coaxial electrospun safety battery separators.
Recently, the team of Associate Professor Zheng Gaofeng at our institute has developed a "powerful" and fire-resistant core-shell membrane using a one-step coaxial electrospinning process for battery separators, providing a new method for preparing high-performance and safe battery separators. The related achievements have been published in the international journal ACS. Applied Materials & Interfaces (IF=9.5) under the title "Coaxial Electrospun Tai Chi-Inspired Lithium-Ion Battery Separator with High Performance and Fireproofing Capacity."
Developing high-performance, flame-retardant separators is key to enhancing battery safety and efficiency. Electrospun nanofiber membranes are widely used as battery separators due to their high porosity, high liquid absorption, and corrosion resistance. Adding flame retardants is an effective method for preparing flame-retardant electrospun separators. To prevent organic flame retardants from leaking into the electrolyte and affecting electrochemical performance, despite the fabrication of battery separators with good flame retardancy and high electrochemical performance, the issue of severe shrinkage of the separator at high temperatures remains a major challenge. Moreover, built-in flame retardants inevitably reduce flame retardancy efficiency.
Inspired by Tai Chi, Associate Professor Zheng Gaofeng's team has developed a new strategy of nurturing both inside and outside to resist high temperatures and achieve stronger flame retardancy. Coaxial electrospinning is a special process that can help prepare core-shell nanofibers with special structures and functions (as shown in the figure below). (Schematic diagram of the coaxial electrospinning process used to manufacture TPP@PVDF/SiO2/GO fibers) The team prepared a safe, high-performance core-shell structured TPP@PVDF/SiO2/GO separator through coaxial electrospinning. The outer layer of GO and SiO2 endows the fibers with good electrochemical performance and thermal stability; the inner layer of TPP avoids the issue of early leakage of electricity leading to a decline in electrochemical performance, while also providing the fibers with excellent flame retardancy. The TPP@PVDF/SiO2/GO separator has a shrinkage rate of only 3.79% at 150°C, which is about 10% of the shrinkage rate of the PVDF@TPP separator (33.9%). The initial capacity of the TPP@PVDF/SiO2/GO separator battery reaches 164 mA hg–1 at 0.5C, and after 100 charge-discharge cycles, it still maintains 95% of the initial capacity. Most importantly, the TPP@PVDF/SiO2/GO separator does not burn in an open flame for 15 seconds and retains 91.2% of its integrity.
This work emphasizes the Tai Chi-inspired strategy of synergistically enhancing fire resistance, rather than just focusing on the coaxial structure itself, which is expected to greatly promote the development of safe, high-performance battery separators. Associate Professor Zheng Gaofeng of our institute is the corresponding author of the paper, and Master's student Zeng Ziyue is the first author of the paper. Graduate students Shao Zun Gui, Shen Ruimin, and Li Haonan also participated in the related work. In addition, the research was guided by Professor Li Wenwang, Professor Wang Xiang, and Teacher Jiang Jiaxin from Xiamen University of Technology. The study was funded and supported by the National Natural Science Foundation of China, Guangdong Natural Science Foundation, Fujian Natural Science Foundation, and Fujian Province Young and Middle-aged Teachers' Education Science Research Project.
Paper link: https://doi.org/10.1021/acsami.3c08757
