Preperation And Electrochemical Performance Of Biomass Based Carbon Materials

Supercapacitors, which are efficient energy storage devices with superior powerdensity, long cycle life, high security, are widely used in the field of portable electronicproducts and hybrid electric vehicles. Currently commercially availablesupercapacitors are of electrical double-layer capacitors (EDLCs). Biomasses arerecyclable and abundant on earth and their conversion into usable carbon is a greenand economical method. In this article, we use three different biomass materials asprecursors to prepare porous activated carbon in the presence of potassium hydroxide.More procedures have been done to optimize the capacitive performance of the overallmaterials.(1) Rice husk was activated with potassium hydroxide to manufacture the porousactivated carbon which has a specific surface area of2523.4m2/g. It performs highspecific capacitance of250F/g in the current density of1A/g and excellent cyclingstability whose specific capacitance remains86.8%after10000cycles.(2) Shaddock peel was transformed to porous activated carbon. Graphene andcarbon nanotubes were used as annexing agent to form flexible freestanding electrodefilm which can be directly used as supercapacitor electrode without binder and currentcollector. The presence of graphene and carbon nanotube not only provides athree-dimensional conductive network but also promote the bending properties vastly.The specific capacitance of activated carbon improved from187F/g to210F/g, therate capability was also improved.(3) Hydrothermal method was used with glucose precursor and graphene oxidedispersion to fabricate layer-by-layer graphene-activated carbon composite material.Subsequent activation increases the specific surface of activated carbon to meet theinfiltration of electrolyte and ionic migration. The high electronic conductivity ofgraphene sheets inside ensures the comprehensive electrochemical properties of thematerial.