Flexible high Li+ conductive lithium garnet–based dry solid polymer electrolyte membrane with enhanced electrochemical performance for lithium metal batteries

Abstract

Poor stability of liquid electrolytes against lithium metal anodes and potential high-voltage cathodes in secondary batteries leads to dendrite formation and thermal runaway. In search of alternative electrolytes, solid electrolytes are promising candidates due to higher electrochemical stability and better safety. However, the solid electrolytes have low room temperature Li+ conductivity and weak interface with Li-metal anode/cathode contact. Herein, we report 5 wt% Li6.28Al0.24La3Zr2O12 (LLZA) garnet filler incorporated PEO20/LiTFSI dry solid polymer electrolyte membrane (DSPEM-5) with high Li+ conductivity of 7.70 × 10−4 S cm−1 at room temperature (30 °C). A full cell based on DSPEM-5 membrane, integrated with LiNi0.33Mn0.33Co0.33O2 (NMC) and lithium metal, delivers an initial charge/discharge capacity of 160/158 mA h g−1 at 25 °C with coulombic efficiency of 98% at 0.1 C-rate. This notable result obtained on lithium garnet filler–based DSPEM opens up encouraging direction to design suitable electrolyte for the realization of room temperature high energy density Li-metal batteries.