Developing Tin Anodes for Aqueous Batteries

Abstract

Aqueous batteries based on metal anodes present an attractive alternative to lithium-ion for long-duration energy storage due to their low-cost, high-safety, and theoretically high energy density. Still, despite many efforts towards development and commercialization, metal anode systems remain hampered by irreversible hydrogen evolution (HER), detrimental shape change, and passivation during cycling. Recognizing the immediacy required to enable the renewable energy transition, our research is focused on developing alternative anode chemistry based on Tin (Sn) for aqueous batteries.Sn metal 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 development of pouch cells to enable aqueous cells while minimizing the side reactions from cell components other than the active materials. Preliminary data demonstrate the feasibility of using Sn as anode active materials via a 4-electron process in aqueous systems. To investigate the mechanism and improve the Coulombic efficiency, we perform operando X-ray diffraction (XRD), rotating ring disk electrochemistry (RRDE), electrochemical quartz crystal microbalance (EQCM), and 117Sn nuclear magnetic resonance (Sn-NMR) on the Sn system. Lastly, we will show our improvement based on the mechanistic understanding that enables Sn-based full cells with high Coulombic efficiency, high areal capacity, high utilization rate and long capacity retention.