Hierarchical and core-shell structured CuCo2O4@NiMn-LDH composites as supercapacitor electrode materials with high specific capacitance

The bimetallic oxide CuCo2O4 (CCO) is highly promising for supercapacitors owing to the character of high theoretical capacitance, high electrical conductivity and rich redox reactions. However, pure CuCo2O4 compo-nents do not provide sufficient capacitance and operating voltage in the application. The appropriate collocation as well as design is one of the keys means to improve the performance of the material. Herein, we brilliantly construct hierarchical CuCo2O4@NiMn-layered double hydroxides (CCO@NM-LDH) core-shell heterostructures, which exhibit impressive capacitive performance (2955.2 F g-1) compared to individual CCO materials (750.2 F g-1). The foremost reason is ultrathin NiMn-LDH nanosheets anchored evenly on the surface of CCO nanoneedles and this structure provide a large specific surface area, numerous active sites, and accelerate the efficiency of ion transport. Also, by modulating the reaction time of NiMn-LDH, several different samples are prepared, among which, the CCO@NM-LDH-2 electrode is found to be the one that can display the best-performance capacitance and retention of capacitance can maintain 86.6 % during 10,000 cycles. In addition, the assembled CCO@NM-LDH-2//AC asymmetric supercapacitor (ASC) with CCO@NM-LDH-2 as the positive electrode can exhibit an energy density of 62.93 Wh kg-1 at 799.96 W kg-1 power density. Therefore, we believe that the construction and utilization of CuCo2O4 composites as electrodes should have a powerful enlightenment on the exploration of energy storage devices.