Investigation on the electrochemical performance of hybrid zinc batteries through numerical analysis

Abstract

With the rapid expansion of the electric vehicle market, the demand for advanced energy storage technologies is increasing strongly. An alkaline hybrid zinc battery with cobalt oxide as the positive electrode material combines the advantages of the high working voltage of Zn–Co batteries and the excellent discharge capacity of Zn–air batteries simultaneously. However, the development of hybrid zinc batteries is limited by their low energy efficiency and poor cycling stability. To investigate the charge–discharge behaviors of hybrid zinc batteries, a mathematical model is established, coupling the mass transport inside the porous electrode with energy conversion. Then, the effects of discharge depth, reaction interfaces, and active material degradation on energy efficiency are investigated through numerical analysis. It is found that within a proper region, the higher ratio of two-phase and three-phase interfaces can lead to higher energy efficiency, and the increase of the two-phase interfaces is beneficial for improving energy efficiency. While the effects of active material degradation on energy efficiency are significant, resulting in poor cycling stability. This work is favorable for the design of interfaces and the selection of operating conditions, and guides the performance improvement of hybrid zinc batteries.