An in-situ generated composite solid-state electrolyte towards high-voltage lithium metal batteries

The solid-state electrolyte(SSE) has promising applications in next-generation lithium(Li) metal batteries(LMBs) because of its significantly enhanced safety and more compatible interface characteristics than flammable traditional liquid electrolytes.However,only a few attempts have achieved high-performance high-voltage LMBs,which is attributed to the fact that both high ionic conductivity and good compatibility with electrodes can hardly be achieved simultaneously.Herein,a composite solid-state electrolyte(CSE) based on star-shaped siloxane-based polymer electrolyte coupled with Li_(6.75)La_(3)Zr_(1.75)Ta_(0.25)O_(12)(LLZTO)ceramic fillers is designed and prepared through a facile in-situ polymerization method.The obtained CSE exhibits high ionic conductivity(i.e.,1.68 × 10^(-4) S cm^(-1) at a temperature of 60 ℃),superior anodic stability,and high Li-ion transference number(i.e.,0.53) because of the multifunctional synergistic effect of the polymer electrolyte with LLZTO ceramic fillers.Moreover,the as-developed CSE shows excellent compatibility with Li anodes.As a result,the as-developed CSE enables the development of long-life 4.4-V-class solid-state LMBs with a Li CoO_(2) cathode,with 79.7% capacity retention and 99.74% average Coulombic efficiency after 500 cycles at a 0.5 C rate.Postmortem analysis of cycled batteries confirms that such superior battery performance can be mainly ascribed to the formation of a compatible electrode/electrolyte interface.Furthermore,excellent safety features can be observed in LiCoO_(2)/Li pouch batteries.This work provides an important guide for the rational design of SSEs for high-voltage LMBs.