Mechanistic Insights Into Instability From Single Void Dynamics at the Lithium Metal-Solid Electrolyte Interface.

Among emerging energy storage technologies, lithium (Li) metal anode-based solid-state batteries (SSBs) have drawn considerable attention, as they promise greater energy density alongside improved safety relative to traditional Li-ion cells. Despite this promise, the performance of such systems remains constrained by intrinsic obstacles tied to the nucleation and growth of voids at the Li-solid electrolyte (SE) interface as stripping proceeds. Void morphology and contact distribution jointly dictate the coupled reaction-diffusion behavior at the interface, thereby affecting the interfacial resistance. In the present study, we track the detailed evolution of a single void as Li stripping progresses, characterizing how its shape, size, and overall morphology evolve under the action of the distinct modes of surface diffusion, i.e., terrace, step, and interlayer diffusion. The depth and size attained by the void are strongly governed by coupling between reaction kinetics and the surface diffusion modes, which together dictate the dominant diffusion pathways. In addition, the role of operating temperature in mitigating void growth under high-reaction-rate conditions is examined. Extending the single-void analysis to the collective voids regime, we resolve the progression toward a multi-clustered morphology and determine the critical void fraction value the onset of percolation, beyond which dispersed voids coalesce into a connected network. Understanding these interactions between voids helps identify the mechanisms that control the final interfacial structure and provides guidance for designing stable, low-resistance interfaces in SSBs.