Nanoscale imaging reveals critical plating and stripping mechanisms in anode-free lithium and sodium solid-state batteries

Abstract

Achieving reversible anode-free solid-state batteries hinges on controlling alkali-metal plating and stripping at buried interfaces, yet the underlying nanoscale mechanisms remain unresolved. Here we introduce virtual-electrode low-energy electron microscopy (VE-LEEM), an imaging platform that enables nanoscale visualization of anode formation and dissolution by combining electron beam-induced plating with ultraviolet-driven stripping. By integrating VE LEEM with synchrotron-based photoemission electron microscopy and atomic force microscopy, we track the chemical and morphological evolution of Li and Na anodes during cycling. We uncover a shared dynamic scaling regime governing anode growth, analogous to high mobility thin film deposition, but emerging through distinct morphological pathways dictated by metal-specific surface energetics. This universal scaling behaviour establishes a transferable quantitative framework for comparing anode-free plating across chemistries. In contrast, stripping proceeds through sequential grain-boundary unzipping and cluster decay mechanisms, demonstrating that dissolution is intrinsically asymmetric with respect to plating and leaves behind a persistent interfacial residual layer. These results overturn the common assumption of mirrored plating-stripping dynamics and identify interfacial and grain boundary energetics as fundamental constraints on reversibility. VE LEEM thus provides a general route to resolve buried electrochemical interfaces at the nanoscale and establishes an energetic framework to guide the design of durable, high energy anode free solid state batteries.