Abstract
Potassium-ion batteries, which possess unique advantages such as lower K(+)/K redox potential compared to sodium and superior interfacial charge transfer dynamics, demonstrate considerable viability for grid-level energy storage deployment. However, the development of potassium electrodes remains constrained by sluggish solid-state diffusion of K(+) within electrodes and progressive structural failure by the large volume variation during (de)intercalation, which requires a thorough understanding ionic transport, size effects, and electro-chemo-mechanical properties of electrodes, to achieve rational design and controlled synthesis. This review initiated with a comprehensive evaluation of potassium-based batteries from five aspects: energy density, power density, cycle life, safety, and cost. Afterward, a systematical examination for key aspects of potassium electrodes from a unique perspective is provided, starting with the fundamental scientific issues of transport properties (key features, anomalous cases, regulation, measurement and prediction) and size effects (kinetics, thermodynamics, potassium storage and transport mechanisms), while further discussing the specific electro-chemo-mechanical properties (composition-structure regulation, nanostructure and interface engineering). Additionally, this review highlights the construction of high-entropy electrodes and the pivotal role of machine learning in developing potassium electrodes. This review aims to provide critical guidance for future basic research and industrial applications of potassium electrode materials.