Metal–Organic Framework‐Derived MnO Nanocrystals Embedded in a Spindle Carbon for Rechargeable Aqueous Zinc Battery with a Molten Hydrate Electrolyte

Abstract

Rechargeable aqueous zinc batteries (RAZBs) are emerging candidates for large‐scale energy storage. However, the lack of high‐capacity cathodes because of the electrostatic interactions between Zn2+ and cathode and the inferior electronic conductivity restricts their performance. The operating voltage limitation imposed by water is another barrier for RAZBs. Herein, manganese oxide (MnO) nanocrystals embedded in a spindle carbon matrix (MnO@C) synthesized from a metal–organic framework are used as a cathode. The uniform distribution of fine‐sized MnO (≈100 nm) in the carbonized matrix (≈5 μm) and the intimate connection between them not only increase the utilization of electroactive material but also eliminate the use of conductive additive. By utilizing the molten hydrate electrolyte, ZnCl2·2.33H2O, a discharge voltage plateau approaching 1.60 V and a high reversible capacity of 106 mAh g−1 after 200 cycles are achieved. This research proposes an approach for affordable RAZBs to fulfill large‐scale energy storage.