Characterizing Dendrite Formation in the ASSB using Magnetic Resonance Techniques

Title: Dendrite formation in solid-state batteries arising from lithium plating and electrolyte reduction
Authors: Liu, et al.,
Journal: Nature Materials Link

A comprehensive understanding of dendrite formation in all-solid-state batteries (ASSBs), both spatially and temporally, is far from attainable without a proper characterization method. While numerous studies have investigated dendrite formation at the electrode-electrolyte interface, less effort has been dedicated to deciphering electrolyte grain boundaries, which are theoretically favorable sites also for dendrite formation. Transmission electron microscopy techniques provide spatial resolution of these boundaries and electronic insights; however, they are limited to local, two-dimensional structural information that is susceptible to transformation under electron beam irradiation.

In this study, the authors synergistically combined non-invasive techniques such as nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) to offer both temporal and spatial insights into dendrite formation within a moderately cycled ASSB composed of Li/Li₇La₃Zr₂O₁₂/Li. The study identified two distinct formation routes: (1) the electrode-electrolyte interface route, driven by non-uniform Li deposition/stripping, and (2) the electrolyte grain surface/boundary route, involving Li+ reduction facilitated by defect-induced electronic structures. These mechanisms were differentiated by the relative abundance of ⁶Li and ⁷Li isotopes within the electrolyte. Over the course of cycling until shorting, the study demonstrated in-situ the alternating dominance of these mechanisms at different stages, with stalled growth occurring between.

Magnetic resonance techniques hold promise as non-destructive characterization tools for the battery industry, which is increasingly focused on next-generation technologies, particularly ASSBs.