NiCoO2/NiCoP@Ni nanowire arrays:tunable composition and unique structure design for high-performance winding asymmetric hybrid supercapacitors

Transition metal phosphides(TMPs)are recognized as such promising supercapacitor materials for the practical application,due to their superior electrical conductivity and excellent redox activity.Here,self-supported three-dimensional NiCoP nanoparticles embedded in NiCoO2 nano wires(NiCoO2/NiCoP)electrode consisting of nickel cobalt phosphides(NiCoP)with high activity and nickel cobalt oxides(NiCoO2)with good stability were fabricated by a hydrothermal and phosphorization method.The electrode integrates the advantages of nanowire arrays for fast ion transport and foam Ni for effective charge transport and flexibility.Benefitting the proper composition control of the nanohybrid and unique structure design,the optimized NiCoO2/NiCoP-20 exhibits a high specific capacitance of 3204 F·g-1 at 1 A·g-1 in 3 mol·L-1 KOH aqueous electrolyte in a three-electrode system.Moreover,the asymmetric supercapacitor assembled with the prepared NiCoO2/NiCoP-20 and activated carbon achieves a specific capacitance of 116 F·g-1 with a high energy density of 40.32 Wh·kg-1 at the power density of 800.18 W·kg-1.The practical application is further demonstrated with all-solid-state winding supercapacitor devices,with decent flexibility,in series to light the Central South University(CSU)logo consisting of 21 red LED indicators.