Surface Characterization and Optimization of Porous Zinc Anodes to Improve Cycle Stability by Mitigating Dendritic Growth

Abstract

Zinc-based batteries are a scalable and safe alternative to Lithium-ion batteries due to the nature of abundance, low cost and easy to process. In this work, we have successfully synthesized porous zinc electrodes (PZEs) via a gel-binder method that can stably charge and discharge for over 700 h at 1 mA cm−2 before showing signs of failure. We compared PZEs synthesized from small (60 nm), intermediate (10 μm), and large (150 μm) zinc particles to determine which surface features are best suited to mitigate dendritic growth and to improve electrolyte stability. The zinc deposits on the large PZE shows a stable and flat morphology, which does not form the hexagonal close-packed (HCP) crystal structure that is typically seen on planar zinc anodes. The intermediate PZE has an increased affinity to deposit onto the glass microfiber separator leading to a decrease of active material on the anode that causes instability during galvanostatic cycling. Both planar zinc and small PZE show HCP deposits that are normal to the surface, which result in very poor electrochemical performance. As the particle size increases, the deposits transition from HCP crystals to flat amorphous metal deposits, increasing cyclic stability.