Synthesis Of Nickel-copper Based Sulfide Or Oxide Composite And Their Properties Of Supercapacitor

The energy and environmental issues have led to researchers to find and design new materials that can be used in high-performance energy storage devices.Among many energy storage devices,supercapacitor have attracted considerable attention due to their excellent power density and cycling life,environment friendly,safety and efficiency.Transition metal compounds have become the focus of research about electrode materials used in supercapacitors gradually,because of their unique advantages.The faraday capacitor relies on the fast redox reaction occurring in or near the surface of the electroactive material,and the energy storage performance of faraday capacitors is much better than the electric double layer capacitors,which advantages lie between those of batteries and traditional capacitors.The next focus point is how to further improve the energy density and cycling life of supercapacitor.Among binary transition metal sulfides would have better electrochemical performance in supercapacitor than single sulfide,which can attribute to the synergistic effect,sufficient redox reaction and diversified nanostructure.Growing electroactive material on three-dimensional conductive substrate directly can avoid the"dead zone"area effectively during the electrochemical reaction,which can improve the utilization rate of the material to increase the energy density of the device.Designing electrode material with unique nanostructure based on the network structure of three-dimensional conductive substrate can also improve the stability.Based on the various material types and unique nanocomposite structures,two novel nickel-copper based supercapacitor composite electrode materials with excellent properties are designed and prepared,this article focuses on the following aspects:1.New type clusters of sheet-like nickel sulfide and copper sulfide?Ni₃S₄/CuS?nanohybrids electrode is transformed from its hydroxide precursor through a facile chemical interface method,followed by an anion exchange reaction.The Ni₃S₄/CuS composite electrode delivers much higher capacity of 970 C g^-1 than its hydroxide precursor and those of the pristine nickel sulfide(559 C g^-1)and copper sulfide(148 C g^-1),and displays a good rate capability and cycling stability.When a hybrid supercapacitor with activated carbon?AC?,Ni₃S₄/CuS//AC is assembled,it presents high voltage up to1.7 V and exhibits top energy density of 18.4 Wh Kg^-1 even at high power density of 8500W Kg^-1.Such novel hybrids electrode and its synthesis method mentioned in this work may provide a viable solution for energy storage materials issues.2.The copper hydroxide nanoarrays are grown on the three-dimensional conductive substrate copper foam through the chemical oxidation,then they are transformed into hollow oxide nanorod array with better crystallinity and conductivity through calcination method.The copper oxide nanoarrays are used as a skeleton,the nickel sulfide nanosheets are covered on the skeleton uniformly to form a unique CuO@Ni₃S₂ core-shell nanostructure based on the electrodeposition strategy.The composite electrode exhibits a high area specific capacitance of 12.21 F cm^-2 at a current density of 2 mA cm^-2 and an enhanced cycle stability,also the stability and other electrochemical performance are much higher than those of Cu?OH?₂@Ni₃S₂ composite electrode which used copper hydroxide as skeleton,and Ni₃S₂ electrode with no skeleton.A hybrid supercapacitor is assembled using the CuO@Ni₃S₂ composite electrode and activated carbon?AC?.The single device can work with an output voltage of 1.6 V and provide power density of 8 W cm^-2 at a high energy density of 2.71 Wh cm^-2.When two fully charged hybrid supercapacitors are connected in series,they can light up LED lamps successfully which have different operating voltages.The synthesis strategy of hollow core-shell structure nanocomposites provided in this work can also be extended to the preparation of other transition metal composites,which has great potential in the application of high-performance supercapacitor electrode materials.