Preparation Of Transition Metal Nickel-Cobalt Electrode Materials And Its Capacitive Performance

Supercapacitors have become the focus of research because of their good capacitance performance.However,the low energy density of supercapacitors limit its wide application.In order to improve the energy density of supercapacitors,the binary metal oxide Ni Co₂O₄ with special crystal structure has attracted the attention of researchers.In this paper,flake Ni Co₂O₄ was prepared by electrochemical deposition on foamed nickel substrate.The capacitance performance of Ni Co₂O₄ is improved by compounding Ni O and C materials.The main research contents are as follows:1.NiCo₂O₄-50/NF was prepared on nickel foam using Ni（NO₃）₂ and Co（NO₃）₂ as raw materials using electrodeposition method.The results of the three-electrode test showed the best capacitive performance of this electrode material at a deposition time of 50 min.The area specific capacitance was 560.7 m F/cm² at a current density of 2m A/cm².The capacitance retention was 64.4%after 1000 turns of charge/discharge testing.The energy density and power density of aqueous symmetrical supercapacitor Ni Co₂O₄-50/NF//Ni Co₂O₄-50/NF were 82.17μWh/cm² and 700μW/cm² in the two-electrode test,respectively.The capacitance retention of this supercapacitor could be maintained at 55.1%after 1000 turns of charge and discharge.The device had an energy density of 46.35μWh/cm² and a power density of 1400μW/cm² when assembled into a solid-state symmetrical supercapacitor.2.The NiO-30/NiCo₂O₄-50/NF composite electrode material was prepared on the precursor Ni Co₂O₄-50/NF by electrodeposition method.The best capacitance performance of Ni O-30/Ni Co₂O₄-50/NF obtained after 30 min of electrodeposition could be derived from the three-electrode test results.Its area specific capacitance could reach 717.8 m F/cm².And it was higher than the area specific capacitance of the previous single Ni Co₂O₄-50/NF electrode.The capacitance retention rate reached 74.8%after 1000 cycles of stability test.The aqueous symmetrical supercapacitor Ni O-30/Ni Co₂O₄-50/NF//Ni O-30/Ni Co₂O₄-50/NF was tested in a two-electrode system with a power density of 880μW/cm² and an energy density of 123.0μWh/cm².The capacitance retention rate was 65.3%after 1000 cycles of charge and discharge of the device.The material composite NiO-30/NiCo₂O₄-50/NF was assembled into a solid-state symmetric supercapacitor.The power density and energy density of the device were 960μW/cm² and 24.27μWh/cm²,respectively.3.The C-3/NiCo₂O₄-50/NF composite electrode material was prepared on the precursor Ni Co₂O₄-50/NF using glucose solution as the carbon source by the oven thermostatic heating method.The capacitive performance of C-3/Ni Co₂O₄-50/NF at glucose concentration of 3 mol/L was better after the three-electrode system test.The capacitance retention rate was as high as 81.1%especially after 1000 cycles of charge/discharge test.The energy density of aqueous symmetrical supercapacitor C-3/Ni Co₂O₄-50/NF//C-3/Ni Co₂O₄-50/NF was 522.3μWh/cm² at a power density of 900μW/cm² after a two-electrode system test.The capacitance retention rate was 77.64%after 1000 cycles of charge/discharge test.The energy density and power density of C-3/Ni Co₂O₄-50/NF//C-3/Ni Co₂O₄-50/NF were calculated to be 44.1μWh/cm² and 1800μW/cm²,respectively,in the assembly into a solid-state symmetric supercapacitor.