Preparation And Electrical Properties Of Biomass Porous Carbon Materials

Biomass carbon materials have become a research hotspot due to their sustainable cycle,wide sources,and simple preparation processes.In this thesis,the biomass agaric was used as the carbon source.The dry agaric powder was mix with the sodium chloride solution and freeze-dried,then carbonized in a high-temperature tube furnace.During soaking of agaric,sodium chloride diffuses into the pores of the agaric.After drying,sodium chloride precipitated as crystal particles.In the carbonization process can play a supporting role to avoid collapse of the whole structure of the agaric.When the carbonization temperature is higher than 800 ?,sodium chloride dissolves and its liquid surface can serve as a template to promote the formation of lamellar carbon.Sodium chloride has an effect on the morphology and properties of Auricular carbon materials.After a series of investigations,the following conclusions were drawn:(1)Sodium chloride helps the carbonized product have a loose sheet structure.Through regulation of sodium chloride template ratio,carbonization temperatures and post-treatment of carbonized products,it was found that a three-dimensional lamellar structure was obtained when the ratio of agaric to sodium chloride was 1:10 and the carbonization temperature was 900°C.The thickness of lamellar layer was about 2 nm,and the specific surface area was 752 m2/g.This material has good capacitance performance,and the specific capacitance at the current density of 0.5 A/g is 100 F/g.After acid treatment of the material,the morphology has no change,but some inorganic salt particles can be dissolved,thereby the specific surface area increased to 928 m2/g.At the same time,the capacitance performance is improved,and the specific capacitance at the current density of 0.5 A/g increased to 116 F/g.(2)Based on the previous work,in order to further regulate the structure and composition of carbon materials,ammonium ferrous sulfate or ammonium polyphosphate was incorporated into the preparation process.The experimental results show that ammonium ferrous sulfate or ammonium polyphosphate generates a large amount of gas during high-temperature carbonization.Leading to the lamination more porous,the specific surface area of the product can be increased to 1065 m2/g,however,the performance of the capacitor is not significantly improved,and the specific capacitance at a current density of 0.5 A/g is 97 F/g.(3)Activation is an effective means to increasing the specific surface area of carbon materials.By using KOH as an activator,the carbonized product is further activated at high temperatures.It was found that when the mass ratio of KOH to carbonized product was 4:1 the morphology of the activated products changed dramatically,and the morphology of the stacked layers disappeared,forming a random morphology with multi-level pore structure.The specific surface area can reach 2033 m2/g.At the same time,the performance of the capacitor is dramatically increased,and the specific capacitance is 340 F/g at a current density of 0.5 A/g.