Yanyan Zhu, Shaohua Long, Haitao Li, Fangyi Cheng, Minghong Wu, Haijiao Zhang
High-entropy materials (HEMs) have emerged as an attractive class of materials for electrochemical energy storage and conversion due to their exceptional compositional tunability and unique physicochemical properties. Nevertheless, the fundamental relationship between compositional complexity and functional performance remains poorly understood, and the gap between synthetic advancements and practical applications continues to impede technological deployment. While isolated studies have begun to uncover the basic principles governing HEM behavior, the field remains in its infancy, marked by fragmented insights and a lack of systematic design strategies. This review critically addresses these knowledge gaps by synthesizing recent advances in the field, including definitions, intrinsic properties, synthesis techniques, and multidimensional structural design strategies. Particular emphasis is placed on the application of HEMs in rechargeable batteries and electrocatalysis with a focus on performance metrics and mechanistic understanding. The review also explores the challenges and opportunities associated with integrating HEMs into renewable energy and sustainability frameworks. Through comprehensive analysis, this Perspective clarifies the internal structure-property relationship in HEMs and offers valuable perspectives to guide future research and innovation.