An aqueous rechargeable copper ammonium hybrid battery with good cycling performance

Hybrid aqueous rechargeable batteries have attracted broad attention due to their cost, safety, and environmental advantages. Nevertheless, a large proportion of the reported long-life and high-power performances are accomplished with a low mass-loading at the cathode (2 mg cm-2). To overcome this challenge, we propose an aqueous rechargeable copper ammonium hybrid battery, which includes an NH4+-rich copper hexacyanoferrate (N-CuHCF) cathode, a Cu foil anode and a hybrid aqueous electrolyte (1 M NH4+ + 0.1 M Cu2+). Its operation involves a reversible NH4+ insertion/extraction reaction at the cathode and Cu plating/stripping at the anode. The unique working mechanism enables this hybrid-ion battery to show a long-term lifespan (over 10 000 cycles). Moreover, this battery exhibits high specific capacity and a long-life property (1000 cycles) even with a high mass-loading (20 mg cm-2) of N-CuHCF at the cathode. This work assembles an aqueous rechargeable copper ammonium hybrid battery, which combines the merits of an NH4+-rich copper hexacyanoferrate (N-CuHCF) cathode and the high safety, high capacity, and abundant reserves of a Cu anode.