A high-voltage and high-capacity aqueous rechargeable Zn-organic battery using ion-selective membranes

Aqueous rechargeable Zn-ion batteries (ZIBs) attract increasing attention due to their merits in terms of high safety, low cost, and nontoxicity. However, the use of aqueous electrolyte confines the operating voltage of ZIBs, which is generally below 1.8 V to avoid water splitting. To boost the energy storage capacity, a high areal capacity of cathode and a high discharge voltage plateau are two important factors. Herein, we report a high-capacity and high-voltage ZIB using a polymer cathode and two ion-selective membranes for separating acidic and alkaline electrolytes. The cathode is prepared by electrodepositing poly(4,4′-oxydianiline) onto mesoporous activated carbon, which can deliver a high areal capacity of 5.42 mAh cm−2. Benefited from different electrolytes at cathode and anode sides, this aqueous Zn-organic battery can be operated within an elevated voltage window of 1.3–2.5 V, and shows a high discharge median voltage of ∼2 V. Also, the optimization of electrolyte concentration and the use of additive to improve the Zn anode performance are systematically studied.