Template synthesis of structure-controlled 3D hollow nickel-cobalt phosphides microcubes for high-performance...

Given that combined merits of both compositions and novel structures play important roles in energy storage of electrode materials, we herein use [CH₃NH₃][Ni_xCo_1-x(HCOO)₃] as self-sacrificed precursors to synthesize structure-controlled hollow nickel cobalt phosphides microcubes. The as-obtained hollow NiCoP-2 displays the highest specific capacity of 629 C g^-1 at 1 A g^-1 and superior cycling stability with 81.3% capacitance retention at 6 A g^-1 after 8000 cycles. Moreover, the asymmetric supercapacitor composed of NiCoP-2 and commercial active carbon (YP-80F) presents the remarkable battery storage performance in terms of outstanding specific capacitance (121.5 F g^-1 at 1 A g^-1), excellent cycling durability (90.1% capacitance retention after 10,000 cycles) and high energy density of 43.2 Wh kg^-1 at a power density of 801.6 W kg^-1. The attractive performance can be ascribed to superiority of the transition metal phosphides, hollow structures, as well as synergism between Ni and Co.