Disorder by Design: Rethinking High-Entropy Hydroxides Across the Structural Landscape for Coupled Energy Conversion and Storage.

High-entropy hydroxides (HEHs) have attracted growing interest as multifunctional materials for energy conversion and storage. Their multi-element compositions allow local coordination environments and electronic structures to be tailored, which accelerates interfacial charge transfer and optimizes reaction kinetics for electrocatalysis. Entropy-stabilized lattices and distortion-controlled diffusion pathways further support reversible ion transport and structural stability, leading to enhanced rate capability and cycling stability in energy storage. Furthermore, beyond the hydrotalcite structure, HEHs cover a structural landscape including perovskite and amorphous phases, which are accompanied by electronic coupling and coordination effects that enhance overall performance. However, the multicomponent nature of HEHs complicates mechanistic analysis and limits their practical application. Key bottlenecks include clarifying the specific roles of individual elements, the limited understanding of dynamic structural evolution and its coupling with reaction processes, and the challenge of identifying the main origins of performance degradation. To address the above issues, this article systematically reviews recent advances in HEHs for energy conversion and storage, highlighting definitions, fundamental effects, synthesis routes, and regulation strategies, while using representative studies to clarify how composition and structure govern performance. Finally, we discuss new opportunities and challenges for HEHs in energy conversion and storage, and propose future research directions and optimization paths.