Effects of the Low Coulombic Efficiency of Zinc Anode on the Cycle Performance of Zn–Ni Battery

Abstract

Zn–Ni battery is an attractive aqueous alkaline secondary battery due to its low cost, safety, and environmental friendliness. However, the problems of hydrogen evolution reaction, zinc dendrites growth and deformation of zinc anodes hampering the commercial application of Zn–Ni battery. In this work, the dynamic imbalance behavior of capacity of the Zn–Ni battery which caused by low coulombic efficiency of the anode is studied. Results reveal that due to the hydrogen evolution effect of the anode, the sintered Ni(OH)2 cathode which commonly used in the research of anode of Zn–Ni batteries cannot be fully discharged. Residual capacity will increase the potential of the cathode continuously, shorten the constant current charging time, and cause the battery cycle capacity decay rapidly. This phenomenon is confirmed by adding nano Bi powders to suppresse the hydrogen evolution of the zinc anode. This work reveals that the decline in the cycle life of Zn–Ni batteries is not only due to irreversible changes in the electrode structure but also due to the coulombic efficiency mismatch of the cathode and anode.