Biomass Derived Carbon As Supercapacitors Electrodes

Supercapacitors is a new kind of energy storage component between rechargeable batteries and conventional capacitors. Owning to their high surface area?high power density?wide working temperature range?long cycle life?fast charge-discharge rate capability and environmental friendliness, they have been extensively applied in electric vehicles, communication equipment, energy, and other fields. Porous carbon with great specific area requires low production costs and its electrochemical performance is relatively excellent, which has become generally used by researchers for supercapacitors.Biomass is from nature and belongs to the renewable carbon carrier, which can be recycling and exploited. Glucose is widely distributed in nature and the most important kinds of monosaccharide; Bacterial cellulose is a kind of natural cellulose by microbial synthesis of different bacterial species and has a large production and variety in the tropics. Based on cheap glucose and bacterial cellulose as raw materials through the activation and high temperature carbonization for modification, we achieved excellent porous carbon as the electrode materials of supercapacitors. In addition, we also explored the influence of different doping elements and carbonization temperature on the performance of electrode materials. The main research content is as follows:(1) Sulfur/phosphorus co-doped porous carbon was fabricated by solvent evaporation and high-temperature carbonization using glucose as carbon precursor. We explored the action mechanism of the phosphorus and sulfur elements on structure and electrochemical properties. Electrochemical spectroscopy shows that Sulfur/phosphorus co-doped porous carbons prepared at 800? possessed the best electrochemical properties with the specific capacitance reaching 180F g-1 and 122 F g-1 at 1A g-1 in 1M H2SO4 and 6M KOH, respectively. In addition, the electrode exhibits highly stable cyclability, showing no capacitance deterioration after the 10000 charge/discharge cycles at 1 A g-1 in 1M H2SO4 and slight deterioration after 1000 charge/discharge cycles at 3 Ag-1 in 6M KOH.(2) Honeycomb-like porous carbon was fabricated by KOH activation and high-temperature carbonization using Bacterial cellulose as carbon precursor at temperature between 700? and 900?. We discussed the distinction of the surface structure and electrochemical performance of the electrode materials due to the different temperature. Electrochemical spectroscopy shows that 800? is the optimum temperature, its specific capacitance reaches 310F g-1 at 0.5A g-1 in 1M H2SO4 and 220F g-1 at 10A g-1 after 5000 charge/discharge cycles, showing excellent highly stable cyclability.