Revealing the Design Principle for Highly Compositional Reversible Transition Metal Chalcogenide Electrodes: A Perspective.

Transition metal chalcogenides (TMCs) are considered a promising kind of anode material for next-generation alkali metal ion batteries (AMIBs) due to their multielectron-transfer energy storage mechanism and low cost. However, their sluggish reaction kinetics lead to irreversible conversion reaction during cycling, resulting in low compositional reversibility and rapid battery failure. To improve their electrochemical performance in AMIBs, many efforts involving structure, composition, and interface modifications have been devoted. However, there is still a lack of a systematic understanding of the reversible conversion reaction mechanism and design principle for highly compositional reversible TMC electrodes. This perspective discusses the reversible conversion mechanism and key challenges of TMCs through a combination of computational and experimental approaches. Three kinds of modification strategies, including multi-scale structure construction, fabrication of TMC-based composite, and interfacial engineering, along with their working mechanisms on promoting the reversible conversion reaction of TMCs, are comprehensively elucidated. Finally, the current general design principle for compositional reversible TMC electrodes in AMIBs is summarized, while future research opportunities are discussed. This perspective provides fundamental and instructive insights for rational design and synthesis of highly reversible electrodes in conversion-type batteries.