High‐Entropy Prussian Blue Analogues for Electrochemical Energy Storage

ABSTRACT The accelerating global energy transition calls for safe, low‐cost, and scalable electrochemical energy storage beyond lithium‐ion batteries. Prussian Blue analogues (PBAs) are attractive open‐framework electrodes, yet conventional PBAs often suffer from structural degradation triggered by phase transitions, lattice vacancies/crystal water, and Jahn–Teller (JT) distortion, which collectively cause sluggish kinetics and rapid capacity fading. Recently, high‐entropy Prussian Blue analogues (HE‐PBAs), built by incorporating five or more transition‐metal species into the same lattice site, have emerged as a powerful platform to address these limitations. Entropy‐driven phase stabilization and the cocktail/lattice‐distortion effects can suppress harmful phase transitions, mitigate JT stress, and promote quasi‐zero‐strain solid‐solution reactions, while simultaneously improving ion/electron transport and activating additional redox centers. In this review, we summarize controllable synthesis strategies (coprecipitation with kinetic regulation, temperature‐directed phase tuning, and structure‐directed routes), discuss multimodal characterization methods to establish rigorous structure–property relationships, and highlight mechanistic insights into high‐entropy effects. We further survey the electrochemical applications of HE‐PBAs across sodium–/potassium‐ion batteries, multivalent‐ion batteries, and lithium–sulfur systems, and provide an outlook on remaining challenges toward practical deployment.