Ag0 nanoparticles and Ag+ interlayer synergistically facilitating the superior capacitance and ultralong cycle of MnO2 through one-step electrodeposition

Abstract

Layered manganese oxide exhibits rich active sites, variable valence states, and economic feasibility, which collectively attract significant attention. However, its poor conductivity and high solubility in water lead to diminished capacitance and stability as an electrode in aqueous batteries or supercapacitors. In this study, Ag⁰ and Ag ⁺ can be incorporated into birnessite MnO₂ for supercapacitors using a straightforward one-step electrodeposition method. Trapping Ag⁺ within the layers regulates the electronic structure and mitigates dissolution, while the incorporation of Ag metal particles enhances charge transport. Leveraging the synergistic effects of Ag⁰–Ag⁺, Ag–MnO₂/CC achieves a superior specific capacitance of 706 F/g at 1 A/g, which is 1.9 times higher than that of MnO₂/CC. It also exhibits outstanding rate performance of 67.6 % at 5 A/g and excellent cycle stability, with 118 % capacity retention after 20000 cycles at 10 A/g. This work presents a novel strategy for the simultaneous deposition of Ag nanoparticles and pre-intercalation of Ag⁺ ions, thereby achieving extended cycling stability for MnO₂.