Rich-grain-boundary Ni-Co-Se nanowire arrays for fast charge storage in alkaline electrolyte.

In this work, the one-dimensional (1D) Ni-Co-Se nanowire arrays with rich grain-boundaries were prepared through the solvothermal method and gas-phase selenizaiton. The results showed that the structure and crystallization of the Ni-Co-Se nanowire arrays could be modulated through the optimization of selenizaiton time. The optimal Ni-Co-Se electrode sample displayed an area specific capacitance of 242.6 μAh cm-2 at 30 mA cm-2 with a current retention rate of 68.34%. The assembled Ni-Co-Se/Active carbon (AC) electrode-based asymmetric supercapacitor (ASC) showed the area specific capacitances of 329.2 μAh cm-2 and 225.8 μAh cm-2 at 3 mA cm-2 and 30 mA cm-2, respectively. A 73.33% retention rate of capacitance was observed after 8000 charge/discharge cycles. Besides, the further fabricated all-solid ASC delivered the power densities of 342.94 W kg-1 and 3441.33 W kg-1 at the energy densities of 37.62 Wh kg-1 and 25.81 Wh kg-1, respectively. Those results suggested the potentials of the obtained Ni-Co-Se nanowire arrays as electrode material for the high-performance pseudocapacitors.