Growth of Al and Co co-doped NiO nanosheets on carbon cloth as the air electrode for Zn-air batteries with high cycling stability

The air electrodes with high activity toward oxygen electrocatalysis and high stability are essential for high-performance Zn-air batteries. Herein, we report an electrode made of Al and Co co-doped NiO nanosheets, which are directly grown on the surfaces of carbon cloth without the addition of binders, facilitating the transport of electrons. Additionally, the hierarchical structure shortens the length for species transport and provides abundant active sites for reactions. In the alkaline solution, the Al and Co co-doped NiO electrode exhibits higher activity in both oxygen reduction and evolution reactions than the pristine NiO electrode without doping and superior stability. When assembled in a Zn-air battery, impressively, this electrode results in stable charge-discharge voltage gaps and energy efficiency of 62% over 1000 cycles (330 h) at 5 mA cm⁻². In comparison, a battery with the electrode made of Pt/C and Ir/C shows large voltage gaps and can only be operated for 400 cycles. The characterization of the electrode after cycling illustrates that both the nanosheet morphology and the NiO phase are well maintained. The results demonstrate that the carbon cloth with Al and Co co-doped NiO nanosheets is a promising air electrode to enable the high cycling stability of rechargeable Zn-air batteries.