Preparation And Electrochemical Properties Of Defect-rich Ni-Co Based Supercapacitor Electrode Materials

With the rapid economic development,energy shortage and environmental pollution problems force people to look for green renewable energy to replace fossil energy.Green renewable energy sources such as solar,wind,and tidal energy have received a lot of attention,but the intermittent nature of these energy sources makes the development of high-performance energy storage devices crucial.Due to its high power density,fast charging rate,wide operating voltage window and long cycle life,supercapacitors have attracted widespread attention from researchers and energy storage device companies around the world.The development and optimization of high-performance electrode materials is the key to improving the power storage performance of supercapacitors.In this paper,NiCo double-layer hydroxide and NiCo sulfide electrode materials were synthesized by hydrothermal reaction using nickel foam as the substrate,and abundant cationic defects were constructed on the electrode surface by low-temperature calcination,pickling and other methods,which effectively improved the Capacitive properties of materials.The specific contents of this study are as follows:（1）Preparation of cation-rich defect NiCo double-layer hydroxide（D-NiCo-LDH/NF）electrode material.NiCo-LDH precursors were grown on foamed nickel substrates by hydrothermal reaction,and D-NiCo-LDH/NF electrode materials rich in Co ions were prepared by low-temperature calcination and secondary hydrothermal method by utilizing the memory effect of LDH..Electrode materials were characterized and analyzed by scanning electron microscopy,transmission electron microscopy,electron paramagnetic resonance,and x-ray diffraction,and electrochemical tests were performed on the materials on an electrochemical workstation.At a current density of 1 A/g,D-NiCo-LDH/NF has a specific capacitance of 3200F/g,the assembled device has an energy density of 53 Wh/kg at a power density of 752 W/kg,and the device still maintains 94.7%of the capacity after 5000 cycles.（2）Preparation of cation-rich defect NiCo₂S₄（v-NiCo₂S₄-8,8 represents pickling time）electrode material.NiCo Mg-LDH precursor was synthesized on nickel foam by hydrothermal reaction.According to the characteristics that Mg S cannot exist stably in hot water,NiCo Mg-LDH was converted into NiCo₂S₄@Mg（OH）₂,and then immersed NiCo2S4-Mg（OH）2 in ammonium sulfate solution for 8 h to wash away the Mg²⁺to obtain v-NiCo₂S₄-8 electrode material rich in cationic defects.The electrode materials were characterized and analyzed by scanning electron microscopy,transmission electron microscopy,electron paramagnetic resonance,and x-ray diffraction,and electrochemical tests were performed on the materials on an electrochemical workstation.At a current density of 1 A/g,v-NiCo₂S₄-8 has a specific capacitance of 2437 F/g,and the assembled device retains 93.6%of its capacity after 5000cycles.