High Li-ion conductive composite polymer electrolytes for all-solid-state Li-metal batteries

Abstract

Rechargeable all-solid-state batteries have better safety and higher energy density than the commercial rechargeable Li-ion batteries with organic liquid electrolytes. However, it is still quite challenging to develop a thin, flexible and high Li-ion conductive solid electrolyte for all-solid-state batteries. Here we develop a flexible poly(ethylene oxide) (PEO)-based composite electrolyte with high ionic conductivity of 1.3 × 10−4 S cm−1 at 30 °C. Fast Li-ion conductive NASICON Li1.3Al0.3Hf1.7(PO4)3 (LAHP) powders with a high bulk ionic conductivity of 7 × 10−4 S cm−1 at 25 °C are added into PEO-LiTFSI electrolyte to increase the total Li-ion conductivity of the electrolyte. Solid nuclear magnetic resonance (NMR) has been employed to analyze the Li-ion conducting mechanism of the electrolyte. Moreover, the composite electrolyte PEO-LiTFSI-20LAHP with a more amorphous component shows better electrochemical stability than the PEO-LiTFSI electrolyte. The performance of the electrolyte PEO-LiTFSI-20LAHP is also tested in different all-solid-state cells; the composite membrane blocked lithium-dendrite growth, which increases the cycling life of all-solid-state cells.