Performance of Several Excellent Oxide-Based Intercalation Cathodes for Aqueous Zn-Ion Batteries

Abstract

Aqueous Zn-ion batteries (ZIBs) have garnered significant interest in recent years due to their advantages in safety, cost, and energy density, which make them suitable for large-scale stationary energy storage. Cathode materials have been a primary research focus in the early stage of ZIBs development since they are widely deemed a limiting factor to the performance. In general, good ZIB cathode materials are found in oxides with layered and open framework structures, and inorganic/organic hybrids, and follow mechanisms of “intercalation”, “conversion” or a combination of both to store Zn2+ and H+ during discharge. However, dissolution of these cathodes into aqueous electrolytes has been a major cause of the performance degradation of aqueous ZIBs. In this presentation, we first show our fundamental understanding of cathode dissolution mechanisms and development of engineering solutions to address the dissolution and instability issues. We then show through several examples how specially engineered V-oxides based cathodes achieve better dissolution resistance and performance stability using aqueous Zn(OTf)2 and ZnSO4 electrolytes as examples. We expect that the insights in this presentation will advance the understanding of dissolution mechanisms and provide design principles for better cathode materials.