Preparation And Properties Of Carbon Aerogels Modified By Carboxylated Chitosan

Supercapacitor is a new type of energy storage device,which has higher power density and cycle life than battery.It is considered as a new green energy source with wide application prospects.As a key factor affecting the performance of supercapacitors,the research of electrode materials is very important.Carbon aerogels as a new nano-porous materials,with a large surface area,aperture control,high conductivity,etc.,is an ideal material for the preparation of supercapacitor.In this paper,the carboxylated chitosan was added to the precursor of the reaction to prepare a modified carbon aerogel material by sol-gel method,and its specific surface area and pore diameter,graphitization degree,microscopic morphology and electrochemical performance were studied.The main contents of this paper are as follows:1.The carbon aerogels were prepared using resorcinol,phloroglucinol and formaldehyde as raw materials,sodium carbonate as catalyst and carboxylated chitosan as soft template.By changing the amount of carboxylated chitosan,carbon aerogels with different structures and properties can be prepared.The test results showed that when the mass ratio of resorcinol to carboxylated chitosan is 250:1,the carbon aerogels obtained had rich pores and high specific surface area(specific surface area of 736 m²·g^-1,average pore size is 5.03 nm)and the specific capacitance could reach 135 F·g^-1 at a current density of 0.5 A·g^-1.Since the carboxylated chitosan itself had a relatively large molecular weight,clusters could be more easily grown and aggregated,thus shortening the gel time.At the same time,carbon aerogels with carboxylated chitosan as soft templates had a more concentrated pore size structure?7-10nm?.2.The effects of different gel aging time on the microstructure and electrochemical properties of carbon aerogels were investigated.The results showed that the average pore size and total pore volume of the carbon aerogel gradually increased,and the specific surface area and specific capacitance gradually decreased when the aging time of the gel increases.When the gel aging time was 12 h,the carbon aerogels had the largest specific surface area(659.17 m²·g^-1)and the specific capacitance reached the maximum(the specific capacitance could reach 144 F·g^-1 at a current density of 1.0 A·g^-1).3.The electrochemical performances of prepared carbon aerogels were studied at different concentrations of KOH and alkaline electrolytes.The results showed that as the KOH concentration increases,the mass-capacitance of the carbon aerogel increased gradually,but when the KOH concentration was too high,the micropores would crystallize,resulting in a decrease in the specific capacitance.By comparing the electrochemical performance of carbon aerogels in 1 mol·L^-1?M?LiOH,NaOH,and KOH electrolytes,it was found that the mass capacitance in the KOH electrolyte was the largest,and the mass capacitance in the LiOH was the smallest.