Investigation of Microstructural Evolution in All-Solid-State Micro-Batteries through in situ Electrochemical TEM

TL;DR

This paper uses in situ electrochemical TEM to observe nanoscale degradation processes in all-solid-state micro-batteries, revealing crack formation, particle shrinkage, and amorphization that impact battery performance.

Contribution

It provides real-time insights into degradation mechanisms at the nanoscale, informing improved design of durable all-solid-state batteries.

Findings

Cracks form along grain boundaries due to lithium diffusion and stress

Solid electrolyte particles shrink and become amorphous during operation

Grain boundary dynamics are critical to electrolyte stability

Abstract

All-solid-state batteries hold great promise for electric vehicle applications due to their enhanced safety and higher energy density. However, further performance optimization requires a deeper understanding of their degradation mechanisms, particularly at the nanoscale. This study investigates the real-time degradation processes of an oxide-based all-solid-state micro-battery, using focused ion beam lamellae composed of LAGP as the solid electrolyte, LiFePO4 (LFP) composite as the positive electrode, and LiVPO4 (LVP) composite as the negative electrode. In situ electrochemical transmission electron microscopy (TEM) revealed critical degradation phenomena, including the formation of cracks along grain boundaries in the solid electrolyte due to lithium diffusion and mechanical stress. Additionally, the shrinkage of solid electrolyte particles and the formation of amorphous phases were observed. These findings highlight the importance of grain boundary dynamics and amorphization in the performance of solid electrolytes and provide insights into degradation mechanisms that can inform the design of more durable all-solid-state batteries.