Preparation Of Biomass Porous Carbon And Nickel Oxide Composite Materials And Their Supercapacitors Performance

Supercapacitors have attracted much attention in the field of electrochemistry because of their long cycle life,fast charge discharge rate and wide voltage window.According to the energy storage mechanism,super capacitors can be divided into Faraday pseudo-capacitors and double layer capacitors.Electrode material is the key to determine the energy storage mechanism and capacitance performance of super capacitor.We have selected representative electric double layer capacitors'electrode materials such as biomass porous carbon materials and pseudo-capacitors'electrode materials such as nickel oxide nanomaterials for preparation research.XRD,SEM,FTIR,XPS and other methods were used to characterize the microstructure and morphology of the electrode materials.Cyclic voltammetry(CV),galvanostatic charge-discharge(GCD),and electrochemical impedance spectroscopy(EIS)were used to analyze the electrochemical performance.The main contents are as follows:1.Three different waste biomass,cane bagasse,onion,and corn cob were selected as the precursors of carbon sources,and KOH was adopted as the activator.Various porous carbon materials were fabricated by one-step activation plus carbonization method under inert atmosphere.The effects of carbonization temperature on the structure and properties of porous carbon materials were investigated.The best carbonization temperatures of cane bagasse,onion and corn cob were all 800?.The electrode material was assembled for electrochemical test in a three-electrode system with 6 mol·L^-1KOH as the electrolyte.The specific capacities of the carbon materials derived from cane bagasse,onion,and corn cob were 277 F·g^-1and 298 F·g^-1,371 F·g^-1at 1 A·g^-1,respectively.After 1000 cycles GCD at 10 A·g^-1,the capacitance retention ratios of the carbon materials derived from cane bagasse,onion,and corn cob were96.68%,97.11%,and 98.12%,respectively,showing good electrochemical performance.2.Self-assembled nickel oxide nano flower-like material was synthesized by simple and mild solvothermal method using ethanol as solvent,ammonia as precipitant,and P123 as surfactant.The influence of the ammonia content on the electrochemical performance of nickel oxide was discussed.To enhance the capacitive performance of nickel oxide,Ni O/Cu O composite materials,Ni O/GO composite materials,and Ni O/Cu O/GO composite materials were prepared.The effects of different doping types and different doping ratios on the electrochemical performance of nickel oxide were investigated.The four materials were prepared as working electrodes,and electrochemical tests were performed in a three-electrode system.The results showed that the specific capacitances at 1 A·g^-1of Ni O,Ni O/Cu O_-30%,Ni O/GO_{-30 mg},Ni O/Cu O_-30%/GO_{-30 mg}were 523 F·g^-1,872 F·g^-1,1048 F·g^-1,1451 F·g^-1,respectively.In addition,the four samples were tested for rate performance.When the electric current density increased from 1A·g^-1to 10 A·g^-1,the capacitance loss rates were 15.11%,21.34%,17.85%,and 17.17%.The results of the constant current charge and discharge experiment at 10 A·g^-1showed that the capacitance retention rates were 77.25%,78.12%,81.11%and 82.95%after 1000 cycles for Ni O,Ni O/Cu O_-30%,Ni O/GO_{-30 mg},Ni O/Cu O_-30%/GO_{-30 mg},respectively.