Transition Metal Oxides/hydroxides And Sulfides Are Used As Electrode Materials For Supercapacitors

With the increasingly serious environmental pollution and energy crisis,as well as people's strong need for mobile electronic portable devices,medical equipment and other advanced energy storage equipment in production and life,researchers are greatly stimulated to develop clean alternatives and sustainable energy research.For energy storage devices,storage capacity,actual utilization rate and environmental impact can become strict criteria for the evaluation of energy storage devices,and the green and excellent operation of supercapacitors stand out.In addition,the electrode material can be regarded as the focal factor of the ultracapacitor,which is very important in the process of its selection,design and preparation.Therefore,the preparation of highly efficient and novel electrode materials is the main problem to be solved in the future development of clean and sustainable energy technologies.Electrode materials have a wide range of selectivity.Each electrode material has its own inherent physical and chemical properties,such as microstructure,crystal configuration,electrical conductivity and specific surface area.How to optimize and recombine the various properties of electrode materials to obtain complementary electrode materials and thus amplify their electrochemical performance advantages is also the focus of our attention.According to the above ideas,this paper mainly focuses on the research of energy storage materials with high electrochemical activity,easy design and preparation and rich raw materials,such as carbon-based materials,transition metals and sulfides.The main work contents are as follows:(1)Herein,the 3D structure of 2D Y-doped Cu(OH)₂nanosheet supported by nickel foam was successfully synthesized by simple solvent thermal reaction.Interwoven nanosheet structures are anchored to the nickel foam skeleton,which makes full use of its electrochemical active sites and speeds up ion and electron transport.Meanwhile,Y-doped can also improve the inherent conductivity of Cu(OH)₂electrode materials.According to the electrochemical test,the specific capacitance of Y-doped Cu(OH)₂/NF was 2775 F/g at1A/g,which shows good charge and discharge rate and cycling stability(86.2%retention over 6000 cycles).In addition,the Y-doped Cu(OH)₂/NF//AC device also provides good specific capacitance(192.53 F/g at 1A/g)and has an energy density of 60.16 Wh/kg at a power density of 749.98 W/kg.(2)Herein,we prepared a three-dimensional open petal-like multistage nanolayered structure,which was prepared by electrospinning carbonization process to obtain NiO carbon-based nanofibers(NiO-CNFs),which were then combined with highly conductive nickel foam(NF),and then assembled by solvothermal method to assemble Ni-Co LDH nanosheets around the NiO-CNFs/NF.After electrochemical performance test,NF/NiO-CNFs@Ni-Co LDH-10 electrode shows good electrochemical performance(2774.18 F/g at1A/g).In addition,the energy density of the device can reach 65.33 Wh/kg after the NF/NiO-CNFs@Ni-Co LDH-10 is assembled into an asymmetric supercapacitor with a success rate density of 849.97 W/kg(NF/NiO-CNFs@Ni-Co LDH-10//AC).Most importantly,the correct construction of multi-layer nanocomposite structures can provide more possibilities for the development of supercapacitor materials.(3)Herein,we applied the idea of layered preparation,using nickel foam as the preparation substrate,carbon nanotubes as the structural stabilizer,and using the pseudocapacity performance advantage of Ni-Co bimetallic sulfide to prepare multistage NF/CNTs/Ni-Co-S composite electrode materials step by step.After electrochemical performance test,the specific capacitance of NF/CNTs/Ni-Co-S electrode was 2952 F/g at1A/g,and the capacitance value remains 82.9%after 6000 cycles,showing good electrochemical performance.After assembly into NF/CNTs/Ni-Co-S//AC device,the maximum energy density was 76.37 Wh/kg at 800 W/kg power density,which indicates that the research and preparation of NF/CNTs/Ni-Co-S composite materials are useful for the practical application of electrode materials in the future.