Pyrolysis Kinetics Of Carbonation Products Of Bamboo And Its Research On Supercapacitors

Supercapacitor is a new type of energy storage component with long life,high power density and good temperature characteristics.At present,supercapacitors have been widely used in the fields of smart grid,military and electric vehicles.The key to determining the performance of a supercapacitor is the nature of the electrode material.There are two main ways to improve the supercapacitor performance of the electrode material.The one is to increase the specific surface area of the material and optimize the pore structure.The second is to dope the hetero atom to form a hetero atom defect structure.Based on these,this paper uses bamboo as the raw material to prepare bamboo charcoal material through thermal chemical conversion.And then bamboo charcoal material is used as electrode material for supercapacitors to achieve good specific capacitance performance while reducing waste and pollutants.Firstly,steam pyrolysis biochar was prepared by using steam pyrolysis carbonization technology at 200°C with bamboo as raw material,and its pyrolysis kinetics was researched.The activation energies of bamboo and its steam pyrolysis biomass charcoal were calculated by FWO and KAS under different conversion rates.The results showed that for FWO and KAS,the activation energy of bamboo was 88.01¹44.13kJ/mol and88.33¹40.65kJ/mol,respectively.The activation energy of steam pyrolysis biochar was142.19³55.96kJ/mol and 139.31³60.71kJ/mol,respectively.Through research,the activation energy of steam pyrolysis biochar is higher than that of bamboo at the same degree of conversion.TG-FTIR was used to study the weight loss characteristics and functional group changes of bamboo and its steam pyrolysis biochar during pyrolysis?heating rate 10°C/min?,in order to fully understand the difference between bamboo and its steam pyrolysis biochar and explore the reaction mechanism of bamboo steam pyrolysis carbonization technology.Subsequently,taking the supercapacitor capacitor performance as the evaluation standard,the steam pyrolysis biochar was used as the raw material,and the chemical activation method was used to increase the surface area and pore size distribution of activated carbon by adjusting the mass ratio of the activator blending and the activation temperature.The results show that when the mass ratio of steam pyrolysis biomass carbon to activator ZnCl₂ is 1:4 and the activation temperature is 1000?,the activated carbon has a specific surface area of 1,536.07 m²/g,a total pore volume of 1.07 cm³/g,an average pore diameter of 3.11 nm and the pore volume of 0.80 cm³/g when its pore diameter is less than 5 nm.Electrochemical tests show that the activated carbon achieves the best supercapacitor capacitance performance and when the current density is 1A/g,its specific capacitance is 107.4F/g.In order to improve the specific capacitance performance of activated carbon further,the method by doping nitrogen atom is applied to the pyrolysis activation of biomass activated carbon technology.The results show that when NH₄Cl is used as nitrogen source and the concentration of NH₄Cl is in the range of 0.5²mol/L,the lower the concentration of NH₄Cl,the better the nitrogen doping effect,and the higher the specific capacity of activated carbon.When the mass ratio of steam pyrolysis biomass carbon to activator ZnCl₂ is 1:4,activation temperature is 1000°C and NH₄Cl concentration is 0.5 mol/L,the specific capacitance of activated carbon at current density of 1 A/g is 189.2 F/g.The nitrogen content of the activated carbon was 3.43%,and the absolute contents of quatarnary-N?N-Q?,pyridinium-N?N-6?,and pyrrole-N?N-5?were 1.78%,1.2%,and0.07%,respectively.