Construction of MnO2 nanowires@Ni1-xCoxOy nanoflake core-shell heterostructure for high performance supercapacitor

The hierarchical MnO2@Ni1-xCoxOy composites with ultrathin Ni1-xCoxOy nanoflakes uniformly grown on MnO2 nanowire are prepared by a hydrothermal reaction-chemical bath deposition-calcination method, and further investigated on the performance as the electrodes for supercapacitor. The delicately designed core-shell heterostructure takes advantage of the high effective surface area, facile electrolyte diffusion and fast electron transfer. When tested as an electrode material for supercapacitor, the resulting MnO2 nanowires@Ni0.75Co0.25Oy nanoflake composite exhibits the highest specific capacitance of 476.8 F/g at 0.5 A/g, high rate capability with 83.1% retention at 2 A/g and excellent cycling stability with 943% retention of the initial capacitance after 1000 cycles. The smaller charge transfer and electrolyte diffusion resistance are mainly demonstrated to be responsible. The analyses open a new door to develop the optimal nanostructure of electrode materials for high performance supercapacitor. (C) 2016 Elsevier B.V. All rights reserved.