Capacitance Properties Of Graphene/nickel (cobalt-manganese) Hydroxide Composite Electrode

With the rapid development of the economy and the depletion of fossil fuels,the demand for high-power,high-energy-density energy storage devices is increasing.Supercapacitors have attracted the attention of researchers because of their high power density,long cycle life,fast charging and discharging intervals,cleanliness and safety.Nnano-carbon based double-layer capacitors and transition metal compounds based pseudo-capacitors are the research focus in energy storage.Aiming at preventing the irreversible self-agglomeration of graphene during the reduction of graphene oxide,researchers turned to prepared three-dimensional?3D?graphene materials.Furthermore,the capacitive properties of the transition metal hydroxide electrode could be improved by compositing with nanocarbon materials to reduce its electrical resistance.The main research results of this thesis are as follows:?1?A three-dimensional composite electrode of graphene aerogel and nickel foam?GA@NF?was initially prepared by one-pot hydrothermal process and freeze-drying treatment.In comparison with those prepared by the traditional coating technology,the GA@NF electrode demonstrated a larger specific capacitance,higher rate performance and better cycle stability.?2?A ternary Ni?OH?₂/rGO/NF electrode was prepared by one-pot hydrothermal process and vacuum-drying treatment.The composite electrode has a higher specific capacitance.Moreover,an asymetry capacitor?ASC?device was assembled with Ni?OH?₂/rGO/NF as positive and rGO/NF as negative electrodes,which had a high energy density.?3?Three multiplex NiCoMn/NF,NiCoMn/rGO/NF and NiCoMn/GA/NF electrodes were prepared by one-pot hydrothermal process and vacuum-drying treatment.Among them,NiCoMn/rGO/NF exhibits superior electrochemical behavior.Therefore,NiCoMn/rGO/NF is used as the positive electrode and rGO/NF is used as the negative electrode to assemble an asymmetric capacitor.This device has a good application prospect.