High‐Entropy Materials for Next‐Generation Energy Systems: A Decade of Progress in Synthesis, Properties, and Applications

The transition to low‐carbon energy systems is increasingly constrained by the intrinsic limitations of conventional materials, which often struggle to simultaneously deliver high catalytic activity, long‐term stability, and operational durability. Over the past decade, high‐entropy materials (HEMs) have emerged as a transformative materials‐design paradigm that addresses these challenges by shifting from single‐principal‐element optimization to entropy‐driven stabilization of multicomponent, highly disordered solid solutions. This review critically traces the evolution of functional HEMs from their metallurgical origins to their growing prominence in energy‐related ceramic and ionic systems. We elucidate the thermodynamic foundations of the field, examining how the four core effects—high‐entropy stabilization, severe lattice distortion, sluggish diffusion, and the cocktail effect—translate into tangible performance enhancements in electrochemical applications. Adopting a structure–centric framework, we highlight recent breakthroughs across key lattice families, including the suppression of cation segregation in high‐entropy perovskite cathodes for solid oxide fuel cells, the expansion of redox windows in high‐entropy layered double hydroxides for supercapacitors, and the precise electronic tuning of active sites in high‐entropy spinels for nitrate reduction electrocatalysis. Furthermore, we assess advances in synthesis strategies, contrasting thermodynamically driven solid‐state approaches with kinetically controlled solution‐based routes essential for nanoscale engineering.