Stable Oxyhalide-Nitride Fast Ionic Conductors for all-Solid-State Li Metal Batteries.

Rechargeable all-solid-state lithium metal batteries (ASSLMBs) utilizing inorganic solid-state electrolytes (SSEs) are promising for electric vehicles and large-scale grid energy storage. However, the Li dendrite growth in SSEs still constrains the practical utility of ASSLMBs. To achieve a high dendrite-suppression capability, SSEs must be chemically stable with Li, possess fast Li transfer kinetics, and exhibit high interface energy. Herein, we design a class of low-cost, eco-friendly, and sustainable oxyhalide-nitride solid electrolytes (ONSEs), denoted as Li x N y I z -qLiOH (where x = 3y + z, 0 ≤ q ≤ 0.75) to fulfil all the requirements. As-prepared oxyhalide-nitride fast conductors demonstrate chemically stable against Li and high interface energy (> 43.08 meV Å -2 ), effectively restraining Li dendrite growth and the self-degradation at the LMA interfaces. Furthermore, improved thermodynamic oxidation stability of ONSEs (> 3 V versus Li + /Li, 0.45 V for pure Li 3 N), arising from the increased ionicity of Li-N bonds, contributes to the stability in ASSLMBs. As a proof-of-concept, the optimized ONSEs possess high ionic conductivity of 0.52 mS cm -1 and achieve long-term cycling of Li||Li symmetric cell for over 500 h. When coupled with the Li 3 InCl 6 SSE for high-voltage cathodes, the bi-layer oxyhalide-nitride/Li 3 InCl 6 electrolyte imparts 90% capacity retention over 500 cycles for Li||1 mAh cm -2 LiCoO 2 cells. This work heralds a class of stable ONSEs with exceptional Li compatibility, good oxidative resistance, as well as high ionic conductivity to significantly ASSLMBs advance. This article is protected by copyright. All rights reserved.