Synthesis of Porous Yolk-Shelled NiSe2–MnSe Heterojunctions for High-Cycling-Stability Asymmetric Supercapacitor Electrode Materials

Transition-metal selenide materials have the potential to be excellent power storage materials owing to their unique physical and structural features. The porous yolk-shelled NiMnSe 3 nanospheres synthesized by a two-step hydrothermal and thermal treatment process were used as anode electrode materials for an asymmetric supercapacitor (ASC). The unique yolk-shelled structure and the bimetallic synergistic effect contributed to the improved charge transfer capability of the ASC. With density functional theory calculations, the NiSe 2 –MnSe heterojunctions illustrate the synergy between NiSe 2 and MnSe components along with the charge transfer path at the heterogeneous interface. The NiMnSe 3 electrode material has excellent electrochemical properties in the three-electrode system (1093 F g –1 at 0.5 A g –1 ). The ASC using the NiMnSe 3 anode with an activated carbon cathode exhibited a maximum energy density of 74.5 Wh kg –1 and a maximum power density of 8259.3 W kg –1, retaining 99.5% of the initial capacitance after 12,000 cycles. This shows that metal selenide heterojunctions have promising potential for supercapacitor as ASCs.