Application Of Magnesium Cobalt Oxide And Transition Metal Composites In Capacitor

The growth of the population leads to increasing demand for energy,and the intermittent supply of renewable clean energy cannot meet the needs of human beings.Therefore,it is urgent to develop and prepare supercapacitors with the high power density and high charging and discharging speed.The electrode material is an important factor to determine its energy density.Therefore,it is very important to explore and develop electrode materials with excellent performance.In this paper,MgCo₂O₄@Co Fe-LDH core-shell structure material was prepared on nickel foam（NF）by simple hydrothermal combined calcination.In addition,Ni₃Mn₁Co@Co₉S₈-QDs materials were prepared on NF by in-situ chemical bath deposition at room temperature and hydrothermal method.The Na_0.6Co O₂ material was prepared by electrochemical oxidation（EO）,which was based on carbon cloth（CC）and used as the positive electrode of the supercapacitor.Details are as follows:1.MgCo₂O₄@Co Fe-LDH core-shell structure material is prepared on NF by simple hydrothermal combined calcination and applied to the positive electrode of the supercapacitor.Due to its unique core-shell structure,low equivalent series resistance,highly porous structure and large specific surface area,the product MgCo₂O₄@Co Fe-LDH/NF-3 obtained at 90℃for 3 h show excellent electrochemical performance.This makes MgCo₂O₄@Co Fe-LDH/NF materials have great development prospects in the field of supercapacitors.2.Ni Mn Co@Co₉S₈-QDs material is prepared on NF by in situ chemical bath deposition and hydrothermal method and used as the positive electrode of supercapacitor.The results show that Ni₃Mn₁Co@Co₉S₈-QDs electrode with Ni to Mn atom ratio of 3:1 exhibits the best electrochemical performance,and its capacity is up to 492.1 m Ah g^-1 at the current density of 1 A g^-1.Meanwhile,an all-solid-state asymmetric supercapacitor（ASCs）assembled with a positive electrode of Ni₃Mn₁Co@Co₉S₈-QDs and carbon-coated Fe₂O₃（Fe₂O₃@C/CC）electrode on CC as a negative electrode has an energy density of 71.48 Wh kg^-1 at a power density of 750W kg^-1.At the same time,after 10,000 charge and discharge cycles,it can still maintain93.7%of the initial capacity.3.Using Co₃O₄ nanowires directly prepared on carbon cloth as the sacrificial skeleton,Na_0.6Co O₂/CC prepared by electrochemical oxidation can work stably at a wide potential of 0-1.2 V.Meanwhile,Na_0.6Co O₂/CC as a positive electrode,An ASCs device with Fe₂O₃@C/CC as a negative electrode can operate stably at an ultra-wide potential of 0-2.5 V.The device has an energy density of 133.92 Wh kg^-1 at a power density of 1250 W kg^-1.It provides a method for constructing the water asymmetric supercapacitor with high operating voltage and has great development prospects.