Study On Preparation And Electrochemical Properties Of Chitosan Biomass Carbon Based Electrode Materials

Due to high capacity,high energy density,fast charging and long lifetime,supercapacitors have a greater prospect of application in the field of energy storage components.Activated carbon is the earliest electrode material for commercial application in supercapacitors due to its stable nature,low cost and easy synthesis.Currently,the most important problem limiting the development of carbon-based is its low energy density and poor capacitive performance.To address this problem,in this paper,we obtained CS carbon based electrode materials with excellent electrochemical performance by adjusting the pore structure and loading pseudocapacitive materials to improve the specific capacitance of CS carbon materials using natural nitrogen-rich biomass-chitosan（CS）as carbon precursors:Fe₃O₄/CS carbon aerogel,CS porous carbon material and CS loaded with Ni（OH）₂porous carbon.The details are as follows.Firstly,in this paper,CS carbon aerogels（Fe₃O₄/CSC）uniformly loaded with Fe₃O₄ particles were prepared by the in situ generation method using the coordination effect of hydroxyl and amino groups contained in the CS molecular chain on metal ions.This section investigates the effect of the amount of Fe Cl₃·6H₂O introduced on the morphology,structure and electrochemical properties of the composites.Electrochemical tests show that when 0.4 g Fe Cl₃·6H₂O is introduced in 1.0 g CS,the carbon aerogel exhibits a specific capacitance of 457.0 F/g（at a current density of 0.5A/g）,which is about 3.5 times higher than that of the CS carbon aerogel alone.Secondly,CS porous carbon materials（CSPC）with high mesoporosity and graded porous structure were prepared by freeze-drying-assisted activation to modulate the pore structure of CS aerogels.The large effects of activation type and activator ratio on the morphology,structure and electrochemical properties of the prepared CS porous carbon materials were investigated.When the mass ratio of activator to CS aerogel was1:1,the electrochemical properties of the prepared CS porous carbon were relatively the most excellent.Its specific capacitance could reach up to 386.0 F/g（at a current density of 0.5 A/g）in the three-electrode test system.The capacitance retention rate is as high as94.4%after 10,000 consecutive charge/discharge cycles.Assembled into a symmetric supercapacitor,the energy density can reach 15.5 Wh/kg at a power density of 300W/kg.Finally,based on the previous chapter,the prepared CS porous carbon was used as the substrate,and the Ni（OH）₂ spherical structure composed of nanosheets was uniformly loaded onto the CS carbon substrate by hydrothermal method.The cyclic voltammetry test results showed that the Faraday pseudocapacitance contribution from Ni（OH）₂resulted in a significant increase in the electrochemical capacity of the composite（Ni（OH）₂/CSPC）.The doping amount of porous carbon has a large influence on the electrochemical properties of the composites.The specific capacitance of the composites was highest when the doping amount of porous carbon was 20 mg,reaching1446.0 F/g at a current density of 0.5 A/g.