Effect of optimum current-collector design on electrochemical performance of Mg-air primary batteries for large-scale energy storage

Abstract

Recent research has focused on the optimal current-collector design of a large Mg anode for large-scale Mg-air primary batteries. The study investigated the effects of different current-collector contact points (CCPs) on the electrochemical discharge performance and degradation of Mg anodes. The results revealed that the selection of CCPs on the Mg anode plays a critical role in improving the discharge capacity and power characteristics. The current values measured at several anode surface locations varied significantly depending on the CCP position on the Mg anode. This nonuniform current distribution is considered to be the major cause of undesirable degradation of the Mg anode upon discharge. Through numerical simulation based on electric field analysis, optimum multiple CCPs were designed to minimize the Mg anode degradation during the discharge process by alleviating the locally concentrated current in the vicinity of the CCPs of the Mg anode. The Mg anode with multiple CCPs exhibited a highly improved discharge capacity (46.2 Ah) and energy conversion efficiency (42%) compared to the Mg anode with single CCP (38.7 Ah and 35.2%). The multiple contact strategy and improved understanding of the correlation between the current distribution and anode degradation phenomena can be further applied for the optimal design and performance improvement of various types of metal-air batteries, including Li-, Al-, and Zn-air systems.