Abstract
With the increasing development of electric cars and portable electronic devices, the demand for advanced batteries with high energy density, long cycling lifespan, and enhanced safety is growing rapidly. In closed battery systems, a number of complex dynamic behaviors occur during cycling processes, such as chemical and structural changes of electrode particles, formation of solid electrolyte interphase (SEI), evolution of conducting electrode networks and distribution of electrolytes, all of which collectively impact the battery performance markedly. Conventional postcycling and bulk-level, ensemble-averaged electrochemical characterization techniques encounter challenges in establishing clear relationships between the micro/mesoscale structures of battery materials and the overall macroscopic device performance. In this review, we provide a timely overview of recent developments in operando imaging for multiscale characterization of batteries, spanning from sub/single-particle levels and interfaces to the electrode network and full battery levels. Operando imaging techniques shed light on the multiscale dynamic evolution mechanisms within closed battery systems, uncovering deeper understandings of the key factors that govern overall battery performance.