Advanced Characterization Development for Metal Anodes in Aqueous Batteries

Abstract

Renewable penetration of the electric grid necessitates inexpensive and safe energy storage solutions. With these priorities, aqueous batteries with metal anodes (Zn, Al, Mg, Sn, etc.) are an exciting area of development as they have low material costs, inherent safety, and high theoretical energy density. Understanding and quantifying the faradaic and chemical reactions occurring in aqueous alkaline batteries with metal anodes necessitates probing the solid, liquid, and gaseous phases that evolve during cycling. The interplay of plating, stripping, precipitation, disproportionation, and parasitic gases generation complicates our understanding of metal anode cycling behavior and often muddle the real failure mechanisms in aqueous batteries.In our work, we have developed a robust toolbox of direct characterization tools to investigate metal anodes in aqueous batteries. Our investigation focuses on tin (Sn) as a largely unexplored metal anode and characterizes its performance and speciation during cycling. We will present a variety of methods to probe the charge/discharge speciation and efficiency losses to parasitic side reactions, including operando XRD, in-situ gas detection, RRDE, EQCM, and liquid 119Sn NMR. These techniques have allowed us to develop a mechanistic understanding of the Sn metal anode system and construct a high coulombic-efficiency, high utilization, and long cycle-life aqueous battery.