Opportunities for 3D Zinc Anode Architectures in Aqueous Batteries

Abstract

Zinc-based batteries offer a compelling alternative to lithium-ion batteries thanks to nonflammable aqueous electrolytes augmented by the high energy density of Zn-based batteries. We recently demonstrated that fabricating dendrite-prone zinc into a monolithic porous, aperiodic architecture form-factor suppresses zinc migration and dendrite development. Three structural features of these emulsion–derived Zn "sponge" electrodes physically ensure dendrite suppression: (i) interconnected pathways that maintain long-range electronic conductivity within the electrode volume throughout charge–discharge; (ii) an electrified 3D interface that imparts more uniform current distribution; and (iii) confined internal void volume that controls Zn/Zn2+ precipitation/dissolution dynamics and product redistribution. The Zn sponge anodes exhibit unprecedented cyclability at high depths-of-discharge (theoretical DODZn), increased specific capacity relative to conventional powder-bed Zn electrodes, and tens of thousands of cycles at low-DODZn pulse-power profiles, as recently demonstrated in prototype Ni–Zn cells [1]. This breakthrough enables the entire family of alkaline Zn batteries (Ni–Zn, Ag–Zn, MnO2–Zn, and Zn–air) to be reconfigured in extensively rechargeable forms, with energy and power characteristics that are competitive with Li-ion batteries. Our second-generation emulsion protocol improves the volumetric density of the sponge thereby concomitantly improving the energy density and power density of the cell while adding mechanical ruggedness to the anode [2]. We have also introduced additional manufacturing flexibility to sponge fabrication. The potential paths forward for the development and transition of this safer energy-storage technology will be discussed. [1] J.F. Parker, C.N. Chervin, I.R. Pala, M. Machler, M.F. Burz, J.W. Long, and D.R. Rolison, “Rechargeable nickel–3D zinc batteries: An energy-dense, safer alternative to lithium-ion.” Science, 356, 415–418 (2017). [2] J.S. Ko, A.B. Geltmacher, B.J. Hopkins, D.R. Rolison, J.W. Long, and J.F. Parker, ACS Appl. Energy Mater. (doi: 10.1021/acsaem.8b01946).