Architecting\na Stable High-Energy Aqueous Al-Ion Battery

Abstract

Aqueous Al-ion batteries (AAIBs)\nare the subject of great interest\ndue to the inherent safety and high theoretical capacity of aluminum.\nThe high abundancy and easy accessibility of aluminum raw materials\nfurther make AAIBs appealing for grid-scale energy storage. However,\nthe passivating oxide film formation and hydrogen side reactions at\nthe aluminum anode as well as limited availability of the cathode\nlead to low discharge voltage and poor cycling stability. Here, we\nproposed a new AAIB system consisting of an Al_<i>x</i>MnO₂ cathode, a zinc substrate-supported Zn–Al\nalloy anode, and an Al­(OTF)₃ aqueous electrolyte. Through\nthe in situ electrochemical activation of MnO, the cathode was synthesized\nto incorporate a two-electron reaction, thus enabling its high theoretical\ncapacity. The anode was realized by a simple deposition process of\nAl³⁺ onto Zn foil substrate. The featured alloy interface\nlayer can effectively alleviate the passivation and suppress the dendrite\ngrowth, ensuring ultralong-term stable aluminum stripping/plating.\nThe architected cell delivers a record-high discharge voltage plateau\nnear 1.6 V and specific capacity of 460 mAh g^–1 for\nover 80 cycles. This work provides new opportunities for the development\nof high-performance and low-cost AAIBs for practical applications.