Multi-Ion Synergy and Multi-Electron Reactions for Rechargeable Aluminum Batteries

Rechargeable aluminum batteries (RABs) have gained considerable attention as next-generation energy storage systems due to Al’s high theoretical capacity, natural abundance, and inherent safety advantages. However, several key limitations related to ion transport, electrolyte stability, cathode reversibility, and anode interface remain. Remarkably, this review demonstrates that synergistic multi-ion transport mechanisms (involving Al³⁺, AlCl₄⁻, AlCl₂⁺, and AlCl²⁺) coupled with multi-electron redox reactions offer effective strategies to address these fundamental limitations. Specifically, multi-ion participation improves charge transport pathways and reduces kinetic barriers at the electrode–electrolyte interface, while multi-electron redox processes increase theoretical capacity and enhance energy storage efficiency. These mechanisms collectively provide a rational framework for advancing the electrochemical performance of RABs. We systematically evaluate recent progress across 4 interconnected research domains: (a) innovative cathode materials design enhancing structural stability and redox kinetics; (b) advanced electrolyte formulations widening the voltage window and improving ionic conductivity; (c) engineered anode interfaces mitigating passivation and dendrite formation; and (d) computational elucidation providing atomic-level insights into complex reaction pathways and ion solvation structures. Crucially, this work provides essential design principles for high-performance RABs and paves the way for their practical application by establishing fundamental connections between material properties and electrochemical performance.