A meltblown cloth reinforced partially fluorinated solid polymer electrolyte for ultrastable lithium metal batteries

Employing fluorinated solid-state polymer electrolytes (SPEs) has emerged as a promising strategy to form stable solid-electrolyte interphase (SEI) on Li metal, which can regulate the behavior of Li deposition during cycling. However, in-situ polymerization of excessively fluorinated monomers suffers from weak polymerization kinetics and a low degree of polymerization. Herein, a partially fluorinated SPEs with meltblown cloth reinforcement was proposed and synthesized via UV-curing. The partially fluorinated meltblown cloth reinforced SPE (PFMC-SPE) showed significantly improved performances due to the enhanced mechanical properties from meltblown cloth and optimized electrochemical performances from the partial fluorination strategy. The PFMC-SPE possesses both a superior room temperature ionic conductivity (1.0 mS cm-1) and a wide electrochemical stability window (up to 5 V). Furthermore, the Li//LiFePO4 cell can stably work for more than 750 cycles at 1.0 C rate with a capacities retention of 84.7% from 141.2 mAh g-1 to 119.6 mAh g-1 at 30 degrees C. Both employing the reliable and inexpensive meltblown cloth based separators for solid-state electrolytes and the partial fluorination strategy is very promising in developing next-generation ultrastable solid-state lithium batteries.