Supercapacitor Based On Silk Fibroin Derived-porous Carbon Electrode

Biomass-based carbon electrode is the hotspot of supercapacitor research.The excellent electrochemical performance requires carbon materials with high specific surface area,suitable pore size distribution,and high heteroatom doping.The main research work of this paper is as follows:1.Biomass silkworm cocoons were used as a carbon source,and FeCl3 and ZnCl2 were used as activators to activate silkworm cocoons in one step to prepare nitrogen-doped porous carbon materials.As the carbonization temperature increases,the specific surface area,graphitization degree,and specific capacitance of the carbon material also increase;It was found that when the carbonization temperature was 850 ?,the prepared nitrogen-doped carbon material SC-850 had the most excellent electrochemical performance.The SC-850 carbon material exhibits high specific surface area(1285 m2 g-1),hierarchical pore structure,high graphitization(IG/ID=1.05)and nitrogen doping(2.24%).In the three-electrode system,the SC-850 carbon material has a high specific capacitance of 178 F g-1 at 0.5 A g-1;it also exhibits excellent cycle characteristics,and the capacitance retention rate is nearly 100%after 10000 cycle at 10 A g-1.It was found that the nitrogen-doped carbon material SC-850 can operate stably under a 2.0 V voltage window and has an energy density of 14.33 W h kg-1 at a power density of 251 W kg-1,respectively.2.Silk fibroin(SF)derived from biomass silkworm was used as a carbon source,and nitrogen-doped porous carbon material was prepared by one-step activation of silk fibroin with CaCl2 and ZnCl2 as activators.With the increase of the mass ratio of ZnCl2/CaCl2,the microporosity,specific surface area,nitrogen doping content and specific capacitance all appears to increase first and then decrease.With the increase of carbonization temperature,the degree of graphitization and specific capacitance increase,the amount of nitrogen doped decreases,the pore morphology changes from circular to square and then to ellipse.The specific surface area and microporosity have no obvious changes.It was found that when the ZnCl2/SF ratio was 1.0 and the carbonization temperature was 900?,the microporosity,specific surface area,nitrogen doping content,and specific capacitance reached the maximum,which were 84%,1549.22 m2 g-1,4.3%,and 216.5 F g-1(1 A g-1),respectively.The resulting carbon material NPC-900-1.0 exhibits excellent electrochemical performance.The NPC-900-1.0 has a high specific capacitance of 216.5 F g-1 at 1 Ag-1.The NPC-900-1.0 exhibited excellent cycle characteristics.The nitrogen-doped carbon material NPC-900-1.0 was found to operate stably at a 2.2 V voltage window and had an energy density of 23.91 and 22.68 W h kg-1 at power densities of 543.8 and 1077.1 W kg-1,respectively.