Double-shelled tremella-like NiO@Co3O4@MnO2 as a high-performance cathode material for alkaline supercapacitors

Tremella-like NiO@Co3O4@MnO2 particles of core-double-shelled structure were synthesized by a three-step hydrothermal route and thermal treatment. The hierarchical layered porous structure of the particles has a BET surface area of 179.2 m2 g−1. Galvanostatic cycling in 6.0 M KOH aqueous solution produced capacitance over an ideal cathode potential cycling range. At a high current density of 2 A g−1, NiO@Co3O4@MnO2 has a high specific capacitance of 792.5 F g−1 with > 90% capacity retention over 1000 cycles, and a high rate capability of 68.9% of its initial capacitance was also maintained over a 0.2-4 A g−1 current density increase. We conclude that NiO@Co3O4@MnO2 offers a promising high rate, high specific capacitance cathode material for alkaline supercapacitors, which owes both to its porous architecture and its synergistic mixed oxide core-shell-shell composition.