Preparation And Properties Of Self-supporting Metal Compound 3D Electrodes For Hybrid Supercapacitors

Recently,hybrid supercapacitors have received widespread attention due to their improved energy density without sacrificing the advantage of high power density of supercapacitors.Hybrid supercapacitors are usually made of battery-type（positive）and capacitor-type（negative）.The construction of hybrid supercapacitors can not only improve the specific capacitance of the supercapacitors,but also broaden their working potential window,thus effectively improving the energy density of supercapacitors.Battery-type electrodes usually exhibit poor conductivity and cycling performance.The above shortcomings can be solved by combining battery-type electrodes with other stable materials.In this paper,three kinds of metal compound based integrated electrodes were prepared through electrochemical deposition and hydrothermal deposition for supercapacitors,and their structure and electrochemical performance were investigated in detail.（1）The hierarchical NiMnS@NiCoLDH@PPy nanosheet arrays on carbon cloth（CC）were prepared via three-steps electrodepostion method.Benefiting from unique structural design,combining with the advantages of each component and synergistic effect,CC/NiMnS@NiCoLDH@PPy integrated electrodes exhibit high specific capacitance of1016.2 F g^-1 at 1 A g^-1 and good cycling performance with 80.2%capacitance retention after10000 cycles.The assembled CC/NiMnS@NiCoLDH@PPy//KOH//NC/CC hybrid supercapacitor delivers high energy density of 55.1 Wh kg^-1 at the power density of 724.6 W kg^-1 and outstanding cycle stability with 81.9%retention after 10000 cycles.（2）Mo doped Co₃O₄ 3D nanosheets arrays on Ni foam(Mo_xCo_1.5-xO/NF)were prepared through one-step electrodeposition method followed by annealing.The effect of Mo addition amount on its electrochemical performance was investigated.The band gap modification and conductivity enhancement of Mo_xCo_1.5-xO due to the doping of Mo into Co₃O₄,leads to its excellent capacitive performance.The as-prepared Mo_0.25Co_1.25/NF electrode shows a high specific capacity of 923.1 F g^-1 at 1 A g^-1 and superior cycle stability with 95.2%capacity retention after 10000 cycles.The assembled HSC delivers high energy density of 64.3 Wh kg^-1at the power density of 794.1 W kg^-1.（3）The hierarchical heterostructures Zn Co₂O₄@Ni Co₂O₄ on Ni foam were prepared through hydrothermal reaction and electrodeposition reaction followed by two post-annealing treatment.Benefiting from the reasonable structure and synergetic effect between different components,the as-prepared NF/Zn Co₂O₄@Ni Co₂O₄-100 electrode exhibits the specific capacitance of 1728.1 F g^-1 at 1 A g^-1 and outstanding cycling stability with 97.8%capacitance retention after 10000 cycles.Furthermore,the assembled NF/Zn Co₂O₄@Ni Co₂O₄//KOH//NC/CC HSC exhibits high energy density of 40.58 Wh kg^-1at 745.62 W kg^-1 and with the capacitance retention of 91.3%after 10000 cycles.