Polyfluorinated Crosslinker-Based Solid Polymer Electrolytes for Long-Cycling 4.5V Lithium Metal Batteries

Solid polymer electrolytes (SPEs), which are favorable to form intimate interfacial contacts with electrodes, are promising electrolyte of choice for long-cycling lithium metal batteries (LMBs). However, typical SPEs with easily oxidized oxygen-bearing polar groups exhibit narrow electrochemical stability window (ESW), making it impractical to increase specific capacity and energy density of SPE based LMBs with charging cut-off voltage of 4.5V or higher. Here, we apply a polyfluorinated crosslinker to enhance oxidation resistance of SPEs. The crosslinked network facilitates transmission of the inductive electron-withdrawing effect of polyfluorinated segments. As a result, polyfluorinated crosslinked SPE exhibits a wide ESW, and the Li vertical bar SPE vertical bar LiNi0.5Co0.2Mn0.3O2 cell with a cutoff voltage of 4.5V delivers a high discharge specific capacity of similar to 164.19 mAh g(-1) at 0.5C and capacity retention of similar to 90% after 200 cycles. This work opens a direction in developing SPEs for long-cycling high-voltage LMBs by using polyfluorinated crosslinking strategy.