In situ construction of fluorine-containing modified gel polymer electrolyte with high interfacial stability for high-rate lithium metal battery

Abstract

Gel polymer electrolytes (GPEs) play a crucial role in promoting the development of lithium metal batteries, as they combine the high ionic conductivity of liquid electrolytes with the enhanced safety provided by solid electrolytes. However, traditional polymer electrolytes are typically poured using non-in-situ methods, which results in poor electrode-electrolyte contact and compromises their performance. In this paper, in situ thermal polymerization is utilized to incorporate di-pentaerythritol pentaacrylate (DPPA) and 3,3,4,4,5,5,6,6,7,7,8,8-tridecafluorooctyl acrylate (TFOA) into PAN spinning porous membranes. Application of TFOA reduces the crystallinity of GPEs and thus enhancing the Li+ transport capability, which enables the newly constructed GPEs to exhibit an ionic conductivity of 2.52 × 10−3 S cm−1 and a lithium-ion transport number of 0.61 at 30 °C. Simultaneously, fluoro-containing groups actively contribute to the formation of a negative solid electrolyte interphase (SEI) film full of LiF, ensuring the stable operation of Li symmetrical batteries for over 2000 h at a current density of 0.40 mA cm−2. The capacity retention rate of lithium metal batteries (LMBs) with commercial NCM811 cathodes reaches 88.2% after 300 cycles. We firmly believe that our newly designed gel polymer electrolytes (GPEs) can offer a viable solution for high-voltage and high-rate LMBs.