Engineering a manganese-based oxide heterostructure cathode for high-performance aqueous potassium-ion storage†
*a
and
Xiaoxia
Liu
*a
Abstract
Advances in aqueous potassium-ion batteries (APIBs) are hindered by the lack of cathode materials with fast K+ transport kinetics and stable structures during K+ intercalation/deintercalation. Herein, a birnessite/spinel Mn3O4 heterostructure cathode is rationally fabricated via a two-step hydrothermal method for aqueous K+ storage. Such structure design provides sufficient heterointerfaces and regulates the electronic structure of the Mn atoms in the material, which greatly facilitates the adsorption of K+. Meanwhile, the Mn dz2 orbital disrupts the long-range collinear Jahn–Teller order of the pure layered birnessite or spinel Mn3O4 phase, leading to the remission of Mn dissolution. Due to these merits, the K0.52MnO2·0.22H2O/Mn3O4 cathode exhibits a high reversible capacity of 147 mA h g−1 at 100 mA g−1 in mild K2SO4 electrolyte, a superior rate capability of 99 mA h g−1 at 2 A g−1, and 91.7% capacity retention after 2000 charge/discharge cycles. This work may provide an efficient strategy for the rational design of heterostructures and suppressing the dissolution of Mn to obtain high-performance cathodes for APIBs.
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