Engineering a manganese-based oxide heterostructure cathode for high-performance aqueous potassium-ion storage

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 K0.52MnO(2)-0.22H(2)O/Mn3O4 cathode exhibits a high reversible capacity of 147 mA h g(-1) at 100mAg(-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.