Rechargeable aqueous zinc-ion batteries (ZIBs) using near-neutral pH electrolytes and inexpensive/abundant raw active materials are a safer alternative to Li-ion batteries, particularly where portability is not of primary importance. Compared to the alkaline Zn-MnO2 battery in which both the zinc electrode and the manganese dioxide electrodes undergo conversion reactions, the chemistry of the ZIB is simplified. Zn2+ is stripped from the negative electrode and intercalates into the positive electrode during discharge. Upon charge, Zn2+ cations de-intercalate from the positive electrode active material and plate back onto the negative electrode as zinc metal. Although common to traditional primary alkaline cells, manganese dioxide has now also emerged as a promising active material for ZIBs. In this work, various forms of manganese dioxide were explored in detail for use as a positive electrode for zinc intercalation. Different crystal structures of MnO2 were studied and several additional factors, such as particle size and morphology were found to impact the performance of Zn2+ intercalation. The diffusion coefficients were calculated and each material was cycled in a zinc-ion battery to determine its suitability as a Zn2+ intercalation electrode in a near-neutral aqueous system. Through this structure-properties correlation, general material design rules can be drawn, guiding future R&D efforts on ZIB chemistry.

Factors impacting zinc cation intercalation into manganese dioxide

2019 Fall National Meeting

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