The Study Of Biomass Carbon Materials And Its Performance For Supercapacitors

With the contradiction between the energy demand in the rapid development of the new economy and the increasing environmental pollution problem,it is an urgent need to find a new energy storage device.Supercapacitors are proposed as future alternative energy storage devices due to the fast charge and discharge rates,high power density,excellent cycle stability and low maintenance costs.Furthermore,supercapacitors not only charge faster but are also more reliable because they are not vulnerable to temperature change.Therefore,supercapacitors have attracted significant attention owing to the research value in scientific community and extensive commercial applications.In this work,three biomass solid wastes were studied as carbon sources,such as samellia seeds,nut shells and soybean residue.The biomass raw materials were comprehensively treated by pyrolysis carbonization,hydrothermal,impregnation and physical chemical activation under different temperatures.The morphologies and microstructures were investigated by X-ray diffractometer,Raman spectrometer,scanning electron microscopy and transmission electron microscopy.These material morphologies were affected by original morphologies of the biomass waste.Therefore,the morphology modifications for these materials were the most important and efficient methods for improving the performance of biomass carbon materials.Researches indicate that the graphene-like carbons were obtained from samellia seeds by a KOH activated hydrothermal method.The activated carbon has unique microstructure characteristics with high specific surface area and abundant porosity.The graphene-like carbons deliver the specific capacitance of 329.1 F g^-1 at a current density of 1 A g^-1,and good cyclic stability of 97.3% capacitance retention after 10000 cycles,indicating high specific capacitance and capacity retention.The activated carbons were prepared from nut shells via impregnation and chemical activation treatment.The prepared carbon has not only abundant micrometric pores on the surface,but also interconnected small pores within the large micrometric pores with 1057 m² g^-1 high specific surface area,delivering the specific capacitance of 325.7 F g^-1 at 1 A g^-1.The soybean residue was carbonized under the temperature from 500 ? to 1100 ?,the graphitization of carbon materials began to increase at high temperatures,and the degree of carbon graphitization was the highest at 1100 ? compared with other carbonization temperatures.The activated carbons were treated with KOH at 900 ? carbonization temperatures,delivering the specific capacitance of 305.7 F g^-1 at 1 A g^-1and good cyclic stability of 98.6% capacitance retention over 10000 cycles.