Chemically bonded single phase ternary anode materials for alkali metal ion batteries: Intrinsic mechanisms and design perspectives

Alkali metal ion batteries (AMIBs) have become important electrochemical energy storage technologies because of their high energy density and long cycle life. However, their electrochemical performance remains largely constrained by the limitations of anode materials. Conventional graphite anodes suffer from limited specific capacity, whereas high capacity binary transition metal compounds are often hindered by severe volume variation and poor electronic conductivity. Chemically bonded single phase ternary anode materials (CBSPTAs), which integrate three elements into a unified chemical framework, provide additional design freedom that is unavailable in binary materials and offer a promising route to overcome these limitations. In this review, we first discuss three common intrinsic mechanisms shared by CBSPTAs, namely functional decoupling of components, stepwise reaction pathways, and reconstruction of ion and electron transport. Building on this foundation, we distinguish the mechanisms specific to dual cation systems, including metal-metal electronic coupling, sequential cation reduction, and cation site occupation, from those of dual anion systems, which comprise charge redistribution, modulation of redox thermodynamics and voltage plateaus, and interlayer spacing engineering. Across these mechanisms, the third element reshapes the local bonding and coordination environment, which governs electronic structure and reaction thermodynamics and thereby reconciles capacity, kinetics, and stability. Finally, we outline the future prospects and practical challenges of CBSPTAs, aiming to provide guidance for the rational design of next-generation AMIB anodes.