Utilization of Hyper-Dendritic Zinc during High Rate Discharge in Alkaline Electrolytes

Abstract

Zinc is a low cost and abundant material, and its strong reducing potential combined with stability in aqueous solutions give it high energy density and safety. It is, therefore, known to be an excellent choice of anode for a wide range of battery designs. However, this material presents some challenges for use in a secondary battery, including morphology changes and dendrite growth during charge (Zn deposition), and low utilization during discharge (Zn dissolution). Low utilization is related to a combination of corrosion and passivation effects. In this paper, we demonstrate a hyper-dendritic (HD) zinc morphology that has a high surface area and allows for rapid discharge in a completely freestanding system with no binders or conductive additives, while still maintaining significantly higher utilization than typical zinc morphologies. At rates of 2.5 A/g, the HD zinc has a utilization level approximately 50% higher than typical zinc granules or dust. Furthermore, we demonstrate that, through tuning of the electrolyte with specific additives, we are able to further increase the utilization of the material at high rate discharge by up to 30%.