High entropy anodes in batteries: From fundamentals to applications

High entropy materials (HEMs) have sparked a technological revolution in the field of battery, opening up new avenues for material composition and performance design. HEMs are unique in that they are composed of five or more elements and are diverse and controllable in both composition and structure. These materials exhibit a range of effects, including high entropy, lattice distortion, hysteretic diffusion and cocktail effect, which enable HEMs to overcome the limitations of traditional electrodes and particularly provide a new perspective for the development of anode materials. Despite the rapid research progress in HEMs as anode materials in recent years, there are still challenges in component tuning, structural design and performance characterization. The aim of this paper is to accelerate the research progress in this field by providing a comprehensive review of HEM anodes and systematically summarizing the research progress. Firstly, the definition of HEMs is introduced and the four main effects associated with them are discussed. The key factors for the rational design of advanced HEM anodes are highlighted, recognizing the critical role of theoretical calculations in the potential development of HEM anodes. The types of HEM anodes are then introduced and common preparation methods are outlined. The applications of HEM anodes in lithium-ion batteries, sodium-ion batteries and potassium-ion batteries are then reviewed in detail. Finally, we outline possible future challenges for HEM anodes, highlighting key issues that remain unresolved and providing researchers with clear directions for development. This review provides a comprehensive and systematic perspective on the study of HEM anodes and aims to stimulate in-depth exploration and innovative development in the field.