Achieving reversible Cu–Al batteries by reducing self-discharge and side reactions

Abstract

3 V rechargeable Cu–Al batteries are highly desirable for large-scale energy storage owing to the low cost and excellent scalability of the two metal electrodes. However, they still undergo irreversible processes such as the crossover of Cu ions, dendrite growth during alloy reaction at Al anode, and side reaction between AlLi and the electrolyte. In this work, we solve the poor reversibility of the battery by modifying the cathode, anode and electrolyte. Specifically, a polyacrylonitrile coating on the copper cathode anchors the dissolved Cu ions, polyvinylpyrrolidone additive in the electrolyte enables dendrite-free AlLi alloy formation and a graphene oxide layer on the Al anode suppresses reductive decomposition of the electrolyte, thereby improving average Coulombic efficiency. Our work overcomes some of the critical challenges in Cu–Al batteries and opens new opportunities for the development of low-cost, high-performance rechargeable metal-metal batteries.