A graphene oxide and ionic liquid assisted anion-immobilized polymer electrolyte with high ionic conductivity for dendrite-free lithium metal batteries

Abstract

Development of solid polymer electrolytes (SPEs) with superior performance is crucial for high-energy density lithium metal batteries (LMBs). Herein, a graphene oxide (GO) and ionic liquid (IL) assisted anion-immobilized polymer electrolyte (PGI) is developed, which can effectively prevent the formation of Li dendrite of LMBs. Various characterizations show that the synergetic interactions among the poly (ethylene oxide) (PEO), GO and IL in PGI, greatly reduce the crystallinity of PEO. All of the amorphous PEO, GO, and IL can effectively tether anions and enhance the ionization of lithium salts, which lead to a uniform assignment of charges and lithium ions in the electrolyte, as well as increase the transfer number of lithium ions. The PGI is utilized in all-solid-state batteries with a negligible polarization. The galvanostatic cycling tests (LiFePO4/Li cells using PGI electrolytes) at 60 °C show the initial capacities of 156.2 and 120 mAh g−1 at 0.1C and 0.5C, respectively. Moreover, the electrochemical tests also indicate that the LMBs using PGI electrolytes possess superior cycle stability at room temperature. The study provides a competitive solution for developing high-performance LMBs which can work well at both high temperature and room temperature.