Study On The Performance Of Supercapacitors Of Loofah Carbon-based Electrode Materials

Supercapacitor(also called electrochemical capacitor,electric double layer capacitor)is a new device for electric energy storage.The electrode material is the most core part of supercapacitor.The associated environmental problem limit carbon materials further development and application.So,the carbon-based materials derived from waste biomass precursors have become more attractive recently.In the thesis,biomass loofa sponge(LS),an low cost and abundant resource is used to fabricate porous carbon.Furthermore,the route of porous carbon materials by the direct carbonization of LS and subsequent activation treatment at high temperature is put forward.In addition,the effects of activators on the pore structure and electrochemical performance of porous carbons derived from loofa sponge have also been investigated.To improve specific capacitance of porous carbon and play a pseudocapacitance behavior of metallic oxide in the process of charge-discharge,we made manganese oxide load on the porous carbon.In this thesis,the biomass loofa sponge pretreated via the H2O2 and NaOH.We found that LS have hierarchical porus tubular structure.Porous carbons were prepared by KOH and ZnCl2 activator.The effects of activators on the BET,pore structure and electrochemical performance of porous carbons derived from loofa sponge have also been investigated.XRD showed that LSPC-KOH and LSPC-ZnCl2 are the amorphous carbon.LSPC-KOH possesses the high BET specific surface area of 3400 m~2/g and quite a number of micropores,this makes LSPC-KOH have good electrochemical performance.Specific capacitance of LSPC-KOH and LSPC-ZnCl2 are 178 F/g and 98 F/g at 0.5 A/g in three-electrode system with 6 M KOH as electrolyte,Based on the experimental results,LSPC-KOH works more effectively on electrochemical performance.Manganese oxide/porous carbon composites were prepared by the thermal decomposition of Mn(NO3)2 that was impregnated in High surface area porous carbon derived from loofa sponge.Result showed that manganese oxides,especially MnO2,produced the Mn(NO3)2 decomposition with mass fraction 1 % manganese nitrate and 500 ? heat treatment an pseudo-capacitance effect,but turned into MnO at 600?.The crystallinitys of manganese oxide were increased with the increasement of the heat treatment temperature.SEM showed that the structure and morphology of manganese oxide dispersed materials are consistent with that of the original porous carbon.There is much difference in pore structure parameters for MOPC-600.The surface area and total pore volume of MOPC-600 were lower than PC.Composites showed excellent performance during reversible charge-discharge and also displayed high stability.Its equivalent series resistance was small.Compared to PC,the electrochemical resistances of composites are increased.The single electrode specific capacitance of composites with mass fraction 1 % manganese nitrate and 500 ? heat treatment reached 212 F/g which is 19.1% higher than that for a pure carbon electrode.It was shown that porous carbon loaded manganese oxide could improve the capacitance of the electrodes.