Enhancing pseudocapacitive performance of CoP coating on nickel foam via surface Ni2P modification and Ni (II) doping for supercapacitor energy storage application

Abstract The pseudocapacitive performance of CoP growing on nickel foam is enhanced via surface Ni2P modification and Ni2+ doping technology. The Ni-doped CoP material and CoP/Ni2P composite have been fabricated successfully using hydrothermal reaction and phosphating reaction. Due to the coupling effect between the doped ion and cobalt ion, or the two-phase composite effect, Ni-CoP and CoP/Ni2P display excellent electrochemical performance compared with the pristine CoP. At the current density of 1 A g−1, the specific capacities of three as-prepared samples are 403C g−1 for CoP, 578C g−1 for Ni-CoP, and 1557C g−1 for CoP/Ni2P, respectively. The modified electrodes show an obvious advantage in the means of energy storage. Meanwhile, they display great stability. Besides, three asymmetric supercapacitors are also assembled. For the device based on the Ni-CoP, when the current density is 1 A g−1, the power density is 1787 W kg−1 and the energy density reaches 44 W h kg−1. For the device based on the CoP/Ni2P, the power density arrives at 1104 W kg−1 and the energy density is up to 53 W h kg−1. Compared with the data of previous papers about supercapacitors with CoP coating electrodes, their performances are more excellent, implying the adopted tactics in the work are achievable.