In-situ synthesis of fluoropolymer-grafted Nanohybrid electrolyte as ion reservoir for Li-metal batteries

Abstract

Heterogeneity in ion flux of electrolyte materials largely dictates the growth of lithium dendrites and performance of lithium metal anode, which is considered “holy grail” to enable safe rechargeable batteries with ultrahigh energy density. This challenge is even more prominent in polymer-based electrolytes, which thereby leads to uneven ion distribution and mobility of ionic charge carriers, disturbing electrodeposition. In this work, we propose an ion-immobilization strategy achieved by an in-situ grafted nanohybrid fluoropolymer electrolyte, which takes advantages of unique weak solvation of fluoropolymers to tether anions to solvation structure of Li+. Such regulation in conjunction with the well dispersed nanometric aggregates, enables polymer electrolytes serving as ion reservoirs with strengthened weakly-solvating effect. As such, we suppressed formation of dendritic lithium by inducing uniform ion distribution, which significantly extended cell lifetime to over 1900 h in electrodeposition and prolonged charge-discharge cycles of in-situ lithium metal batteries up to 4.6 V at ambient temperature. This work demonstrates a new approach to regulate interfacial chemistry of Li anode and access high-performance polymer-based electrolytes.