Research On Chitosan-based Carbon Materials Applied In Lithium-ion Batteries And Supercapacitors

Lithium-ion batteries possess the merits of good cycle stability and rate performance,high energy density,safety and sustainablity.The super capacitors have the advantages of high-power density and energy density,swift charging and discharge speed.The above two energy storage devices have been dramatically applied in industrial,agricultural and high-tech fields of application.Electrode materials play a vital role in the overall performance of lithium-ion batteries and super capacitors.As an important part in the process of electrode materials preparation,biomass carbon materials,due to the advantages of the wide range of sources,environmentally friendly and low prices,have attracted much attention.In this research,through special technology chitosan and its derivatives carboxymethyl chitosan were used as raw materials to synthesize silicon/carbon anode materials for lithium-ion battery,and nicked oxide/porous carbon electrode materials for super-capacitor to improve their performance.To solve the problems of volume expansion(up to 300%),poor conductivity of silicon anode and side reaction between silicon and electrode for lithium-ion batteries,n this research,the carbon source and N source are self-N-doped chitosan which is dissolved in the alkaline system of LiOH/urea by freeze-thaw method and controlling the reaction temperature and reaction time.A sol gel method is developed to form the precursor mixture of Si,silicone oxide and chitosan,followed by high temperature carbonization process to form Si@SiO2@N-C as lithium-ion batteries anode.At the current density of 420 mA g-1 through 200 cycles,its theoretical specific capacity remains above 1026 mAh g-1.Besides,it has excellent rate performance.To solve the problems of poor conductivity of nickel oxide and avoid the consumption of raw material by active agents for super capacitors.In this research,the carbon source and nitrogen source are self-N-doped carboxymethyl chitosan,and in the absence of any active agents,the chitosan of nickel ions gel is firstly prepared by crosslinking effect of nickel ions to carboxymethyl chitosan.The sugar ion gel is then directly freezing dried to obtain the porous carboxymethyl chitosan aerogel interlinked with the nickel ion,and the porous carbon/nickel oxide material is obtained by the subsequent high temperature carbonization,air atmosphere calcination and acid washing process.The productivity is improved dramatically.The specific capacitance of N-C/NiO(20-1)is 345 F g-1 at the current density of 0.1 A g-1.