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Electrolyte-Resistant Dual Materials for the Synergistic Safety Enhancement of Lithium-Ion Batteries

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posted on 18.02.2021, 09:43 by Lien-Yang Chou, Yusheng Ye, Hiang Kwee Lee, Wenxiao Huang, Rong Xu, Xin Gao, Renjie Chen, Feng Wu, Chia-Kuang Tsung, Yi Cui
Safety issues associated with lithium-ion batteries are of major concern, especially with the ever-growing demand for higher-energy-density storage devices. Although flame retardants (FRs) added to electrolytes can reduce fire hazards, large amounts of FRs are required and they severely deteriorate battery performance. Here, we report a feasible method to balance flame retardancy and electrochemical performance by coating an electrolyte-insoluble FR on commercial battery separators. By integrating dual materials via a two-pronged mechanism, the quantity of FR required could be limited to an ultrathin coating layer (4 μm) that rarely influences electrochemical performance. The developed composite separator has a four-times better flame retardancy than conventional polyolefin separators in full pouch cells. Additionally, this separator can be fabricated easily on a large scale for industrial applications. High-energy-density batteries (2 Ah) were assembled to demonstrate the scaling of the composite separator and to confirm its enhanced safety through nail penetration tests.