Achieving widespread implementation of stationary energy storage requires innovative technologies that simultaneously minimize energy cost and maximize cycle life, calendar life, and safety. Aqueous batteries using abundant non-toxic elements and non-flammable aqueous electrolytes are attractive candidates for this application. Zinc metal (Zn) has traditionally been the focus of rechargeable anode development in alkaline electrolytes. However, it is plagued by many problems such as concomitant hydrogen evolution reaction (HER), dendrite formation, and zincate crossover. These problems have been limiting the capacity and cycle life of Zn rechargeable batteries, and may prevent their integration into the grid in the timescale required to accommodate the inclusion of renewable energy sources. Thus, alternative anodes should be investigated to bypass the inherent problems in this century-old technology.

Tin metal (Sn) has been used in aqueous battery systems as additives or current collectors to mitigate side reactions due to its high overpotential for HER. However, little attention was paid to its potential use as a redox active material in aqueous electrolytes. In this talk, we will discuss our efforts to develop Sn as an aqueous anode with high capacity and cyclability. We will first present our fundamental investigations on Sn electrochemistry and its dependence on the composition and pH of the electrolytes. We will then demonstrate our development of pouch cells to enable a Ni(OH)₂-SnO₂ full cell while minimizing the side reactions from cell components other than the active materials. Using an optimized alkaline electrolyte, the pouch cells exhibit high specific capacity and long retention well exceeding our Zn cell counterparts. The results demonstrate the feasibility of using Sn as anode active materials in aqueous systems. Finally, we will touch on our recent efforts of using operando techniques to characterize the conversion pathways and side reactions in this system, as well as our attempts to pair the Sn anode with MnO₂ to further drive down the overall cost.