Energy storage performance of CuO as a cathode material for aqueous zinc ion battery

Rechargeable aqueous zinc ion batteries (ZIBs) with high specific capacity appear promising to meet the increasing demand for low cost and sustainable energy storage devices. Because the investigation of aqueous ZIBs is still in the incipient stage, the exploration of cathode materials with high specific capacity is necessary. Herein, the CuO nanorods were prepared by a simple liquid phase method and for the first time the CuO/Zn system with high and stable voltage platform was established successfully. The discharge platform is at 0.82 V and remains stable throughout the charge and discharge process. The constant current charge-discharge test shows that the CuO/Zn battery within the voltage of 0.4–1.1 V delivers high reversible capacity of 219 mA h g−1 at 0.3 A g−1. The cyclic voltammogram analysis shows that the Zn-ion storage in CuO is a diffusion-controlled kinetic process. Meanwhile, the phase evolution study during the first charge-discharge cycle reveals that the energy storage mechanism of CuO cathode is conversion reaction. The results demonstrate the feasibility of a conversion reaction energy storage mechanism for zinc ion batteries.