Hierarchical MnCo-layered double hydroxides@Ni(OH)2 core–shell heterostructures as advanced electrodes for supercapacitors

Abstract

Rational assembly and hetero-growth of hybrid structures consisting of multiple components with distinctive features are a promising and challenging strategy to develop materials for energy storage applications. Herein, we propose a supercapacitor electrode comprising a three-dimensional self-supported hierarchical MnCo-layered double hydroxides@Ni(OH)₂ [MnCo-LDH@Ni(OH)₂] core–shell heterostructure on conductive nickel foam. The resultant MnCo-LDH@Ni(OH)₂ structure exhibited a high specific capacitance of 2320 F g⁻¹ at a current density of 3 A g⁻¹, and a capacitance of 1308 F g⁻¹ was maintained at a high current density of 30 A g⁻¹ with a superior long cycle lifetime. Moreover, an asymmetric supercapacitor was successfully assembled using MnCo-LDH@Ni(OH)₂ as the positive electrode and activated carbon (AC) as the negative electrode. The optimized MnCo-LDH@Ni(OH)₂//AC device with a voltage of 1.5 V delivered a maximum energy density of 47.9 W h kg⁻¹ at a power density of 750.7 W kg⁻¹. The energy density remained at 9.8 W h kg⁻¹ at a power density of 5020.5 W kg⁻¹ with excellent cycle stability.