α‐MnO₂ Cathode with Oxygen Vacancies Accelerated Affinity Electrolyte for Dual‐Ion Co‐Encapsulated Aqueous Aluminum Ion Batteries

Abstract Aluminum batteries (ABs) are identified as one of the most promising candidates for the next generation of large‐scale energy storage elements because of their efficient three‐electron reaction. Compared to ionic electrolytes, aqueous aluminum‐ion batteries (AAIBs) are considered safer, less costly, and more environmentally friendly. However, considerable cycling performance is a key issue limiting the development of AAIBs. Stable, efficient, and electrolyte‐friendly cathodes are most desirable for AAIBs. Herein, a rod‐shaped defect‐rich α‐MnO₂ is designed as a cathode, which is capable to deliver high performance with stable cycling for 180 cycles at 500 mA g⁻¹ and maintains a discharge specific capacity of ≈100 mAh g⁻¹. In addition, the infiltrability simulation is effectively utilized to corroborate the rapid electrochemical reaction brought about by the defective mechanism. With the formation of oxygen vacancies, the dual embedding of protons and metal ions is activated. This work provides a brand‐new design for the development and characterization of cathodes for AAIBs.