High-entropy Battery Materials: Revolutionizing Energy Storage with Structural Complexity and Entropy-Driven Stabilization

High-entropy battery materials (HEBMs) have emerged as a promising frontier in energy storage and conversion, garnering significant global research interest. These materials are characterized by their unique structural properties, compositional complexity, entropy-driven stabilization, superionic conductivity, and low activation energy. The early 2020 s have seen remarkable advancements in solid-state chemistry and physics, propelled by high-throughput computation and experimentation, which have sparked a revolution in the development of HEBMs. Despite these advances, a systematic understanding of the underlying principles and processes governing HEBMs remains limited. This review provides a comprehensive analysis of the design, synthesis, structural evolution, and entropy stabilization of emerging HEBMs, with a particular emphasis on secondary rechargeable batteries and the design parameters spanning from low to high entropy in both liquid and solid-state technologies. Furthermore, the review explores the impact of multi-component complexity on oxygen evolution, electro-chemo-mechanical behavior, zero-strain performance, and the development of Co/Mn-free anodes and cathodes. We highlight recent breakthroughs in the synthesis of high-entropy solid electrolytes (HESEs) and high-entropy liquid electrolytes (HELEs), including ultrafast synthesis techniques and entropy-driven strategies that enhance ion transport and stability under extreme conditions. The role of entropy in stabilizing multi-component systems, such as high-entropy garnets and argyrodites, is critically examined, emphasizing their potential for high-rate and high-energy density rechargeable batteries. The review concludes by outlining future research directions aimed at advancing the performance and scalability of HEBMs, leveraging computational design and machine learning to overcome existing challenges in the field.