Probing Battery Interfaces and Interphases with Microelectrodes: Spatially and Temporally Resolved Single‐Entity Measurements

Abstract

Understanding batteries at the level of individual particles and interfaces, where critical electrochemical processes actually occur, remains a grand challenge in energy storage research. Traditional characterization techniques often average over complex, heterogeneous structures, obscuring localized events such as nucleation and phase transformation that ultimately dictate battery performance and degradation. Microelectrodes offer a unique opportunity to overcome this limitation by enabling spatially and temporally resolved probing of electrochemical reactions at the microscale. Their reduced dimensions facilitate rapid steady‐state responses, minimal ohmic‐drop, and hemispherical diffusion, making them ideally suited for investigating fast kinetics, localized transport phenomena, and single‐entity redox behavior under realistic battery operating conditions. This review critically examines the growing role of microelectrodes in battery science: from measuring intrinsic charge transfer and diffusion coefficients to mapping morphological transitions and probing interfacial instabilities. It highlights when integrated with advanced characterization tools and operando platforms, microelectrodes can unravel reaction pathways inaccessible to macroscale techniques. Moving forward, it outlines key research directions where microelectrode‐based platforms can make transformative contributions, particularly in non‐equilibrium systems, emerging chemistries, and data‐integrated diagnostics. By reframing batteries as inherently heterogeneous and dynamic systems, microelectrodes emerge as enabling tools for mechanistic understanding and precision control in next‐generation energy storage technologies.