The void formation behaviors in working solid-state Li metal batteries

The fundamental understanding of the elusive evolution behavior of the buried solid-solid interfaces is the major barrier to exploring solid-state electrochemical devices. Here, we uncover the interfacial void evolution principles in solid-state batteries, build a solid-state void nucleation and growth model, and make an analogy with the bubble formation in liquid phases. In solid-state lithium metal batteries, the lithium stripping- induced interfacial void formation determines the morphological instabilities that result in battery failure. The void-induced contact loss processes are quantified in a phase diagram under wide current densities ranging from 1.0 to 10.0 milliamperes per square centimeter by rational electrochemistry calculations. The in situ-visualized morphological evolutions reveal the microscopic features of void defects under different stripping circumstances. The electrochemical-morphological relationship helps to elucidate the current density- and areal capacity-dependent void nucleation and growth mechanisms, which affords fresh insights on understanding and designing solid-solid interfaces for advanced solid-state batteries.

Automated summary

This study uncovers the principles of interfacial void evolution in solid-state batteries and establishes a model for void nucleation and growth. Through electrochemical calculations and in situ observations, the microscopic features of void defects under different stripping conditions are studied, and the quantification of void-induced contact loss processes is conducted. The electrochemical-morphological relationship helps to understand and design solid-solid interfaces for advanced solid-state batteries.