Preparation of high-performance nickel cobalt phosphide and its application in supercapacitors

Abstract

Metal phosphide， as an emerging material for supercapacitors， has attracted more and more attention. In this paper， nickel-cobalt sulfide was obtained by hydrothermal method with carbon cloth （CC） as the substrate and nickel chloride and cobalt nitrate as the raw materials. Then nickel-cobalt phosphide （Ni1/2Co1/2P/CC） was finally obtained by low-temperature phosphating method with sodium hypophosphate as raw materials. Electrochemical tests were performed， and the results show that the specific capacitance of Ni1/2Co1/2P/CC is up to 0.87 F/cm2 at the current density of 2 mA/cm2. After 2000 cycles of charge and discharge at 30 A/cm2， the capacitance retention is 80.22%. In addition， with the Ni1/2Co1/2P/CC as positive electrode and the activated carbon （AC） as negative electrode，the asymmetric supercapacitor （Ni1/2Co1/2P/CC∥AC/NF） exhibits a high energy density of 0.25 mWh/cm3 at the power density of 104.99 mW/cm3.

Keywords

• supercapacitor
• carbon cloth
• pseudocapacitance
• phosphide
• asymmetric capacitor