Novel MnO2/cobalt composites nanosheets array as efficient anode for asymmetric supercapacitor

Cobalt-based composites are generally investigated as cathode for supercapacitor due to its excellent electrochemical properties. Here, we explore its application as anode with the potential window of −0.3–0 V in 6 M KOH aqueous electrolyte. Interconnected Co₃O₄/CoO/Co(OH)₂ nanosheets array is one-step electrodeposited on the surface of active carbon cloth, but showing low capacitance. Surprisingly, after in-situ compositing with MnO₂ (ratio of Mn⁴⁺ is ∼23%), the hybrid MnO₂/cobalt composites nanosheets array anode delivers ∼705 F g⁻¹ at 0.68 A g⁻¹, much higher than that of ∼161 F g⁻¹ for pristine Co₃O₄/CoO/Co(OH)₂. Besides, using NiCo₂S₄ nanosheet array@ nickel foam as cathode, the asymmetric supercapacitor exhibits high specific capacitance of 198 F g⁻¹ at the current density of 0.5 A g⁻¹. This work manifests a promising strategy to explore novel anode material and improve their properties, which holds great promise in energy storage/conversion devices.