Unique MOF-derived hierarchical MnO2 nanotubes@NiCo-LDH/CoS2 nanocage materials as high performance supercapacitors

Nanostructure is the most important aspect in the development of high performance supercapacitors. In this work, we designed and developed new one-dimensional hierarchical hollow nickel-cobalt layered double hydroxide nanocages assembled on MnO2 nanotubes with uniformly dispersed CoS2 nanoparticles, MnO2@NiCo-LDH/CoS2, using a zeolitic imidazolate skeleton (ZIF-67) as the template via multiple hydrothermal and sulfuration processes. This unique one-dimensional hierarchical nanostructure is characterized by a high specific area and high structural stability. The presence of CoS2 nanoparticles in the nanocage increases the electrical conductivity and enhances the stability of the structure. Electrochemical studies show that MnO2@NiCo-LDH/CoS2 electrode materials have a high specific capacitance of 1547 F g(-1) at a current density of 1 A g(-1) and 1189 F g(-1) at 10 A g(-1), exhibiting high rate performance (76.9%) and high stability (82.3%), which is substantially better than the performance of most recently reported similar systems. The asymmetric supercapacitor assembled with MnO2@NiCo-LDH/CoS2 and activated carbon has a maximum energy density of 50 W h kg(-1) and a maximum power density of 9658 W kg(-1). The unique nanostructure and excellent performance of the asymmetric supercapacitor in the present study demonstrate a new platform for developing highly efficient supercapacitor materials with high energy density and high power density.