Metallic zinc as a rechargeable anode material for aqueous batteries has gained tremendous attention with merits of intrinsic safety, low cost, and high theoretical volumetric capacity (5,854 mAh cm-3). Among zinc-based batteries, Zn-air batteries are promising with highest theoretical volumetric energy density (4,931 Wh/L). Rechargeable zinc anode has recently achieved big progress in neutral electrolytes, yet developed slowly in alkaline electrolytes, which are kinetically favorable for air cathodes. Passivation, dissolution, and hydrogen evolution are three main reasons for irreversibility of zinc anodes in alkaline electrolytes. In this work, we report the design of a sub-micron zinc anode sealed with an ion-sieving coating that suppresses hydrogen evolution reaction (HSSN anode). The design is demonstrated with ZnO nanorods coated by TiO2, which overcomes passivation, dissolution, and hydrogen evolution issues simultaneously. It achieves superior reversible deep cycling performance with an electrolyte-to-discharge-capacity ratio as low as 0.14 mL/mAh, discharge capacity as high as 616 mAh/g, and Coulombic efficiency as high as 93.50% at 100% depth of discharge. It can also deeply cycle >520 times (lasting over ~25 days) in a beaker cell with a capacity retention of 621 mAh/g (94.30% Coulombic efficiency). The design principle of this work can potentially be applied to other aqueous and non-aqueous battery electrode materials. 

High-energy, deeply rechargeable and hydrogen-evolution-suppressing anode in alkaline aqueous electrolyte

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.