High-Performance Rechargeable Anionic Zn–Cu Batteries with Facile Recyclability

Aqueous batteries with high safety are ideal large-scale energy storage systems, but still face challenges in cycle life, self-discharge, cost, and environment-related issues. Here, we report a rechargeable aqueous zinc–copper battery with high performance, environmental friendliness, and sustainability. We employed widely available metal foils as electrodes and developed a novel zinc–bromide and cuprous–bromide complex anion-containing anolyte and catholyte, respectively, separated by a cation exchange membrane (CEM), utilizing strong coordination between soft bromide ions and zinc/cuprous ions. The battery exhibited a high areal capacity of 4 mAh/cm2 with stable cycling over 2700 h (>900 cycles), energy efficiency up to ∼90%, excellent 99.6% capacity retention against self-discharge over 3 days, and facile scalability to Ah-level Zn/Cu batteries. Importantly, all elements were recycled at the end of the battery cycle life by simple, cost-effective processes with recovery efficiencies of ∼97% for Zn and ∼100% for Cu. This drastically lowered the battery cost and made the anionic Zn–Cu (AZC) battery promising for energy storage at a low cost with high performance and long-term sustainability.