Study Of Charge-Discharge Performance Of Activated Carbon With Different Structure For Electric Double-Layer Capacitors

Electric double-layer capacitor(EDLC) is a new kind of energy storage device between common capacitors and secondary cells,which can supply higher specific energy than common capacitors,higher specific power than secondary battery and much longer cyclic life.The key component of EDLC is electrode material.Recent years,with development of supercapacitor,various kinds of activated carbon were used as electrode material.However,different kinds of activated carbon have different levels of electrochemical performance for their different morphology and pore structure.In this paper,coal-tar pitch based foam,phenol resin based foam, phenol resin based microspheres and phenol resin based fiber were prepared by thermoplastic phenol resin and coal-tar pitch,respectively. After stabilization,carbonization and vapour activation,different kinds of activated carbon with different morphology and pore structure were obtained.In order to obtain activated carbon with high specific area at high yield,activation processing factors were thoughly investigated. Their morphology and pore structure were characterized with scanning electrical microscope and BET nitrogen adsorption instrument.The electrochemical property was tested at different charge-discharge current and scanning velocity by means of constant direct current and cyclic voltammetry,with 1.5mol/L KOH electrolyte.The result showed that the morphology structure,pore structure and precursor of activateds carbon determined the performances predominately.(1) The specific capacity of the micronscale activated carbon powder was higher than that of nanoscale activated carbon powder.When the BET specific surface area of phenol based micronscale carbon and nanoscale carbon was both around 1200m~2/g,the specific capacity of them was 144.35 F/g and 108.02 F/g at 1 mA charge-discharge current, respectively.(2) The specific capacity of the micronscale activated carbon fiber was higher than the micronscale activated carbon powder,with the same BET specific surface area and particle size.At 1 mA charge-discharge current,the specific capacity of the former was 176.73F/g,while that of the latter was 144.35F/g.(3) The specific capacity of phenol based nanoscale activated carbon microspere was higher than phenol based nanoscale activated carbon powder,with the same BET and particle size.At 1 mA charge-discharge current,the specific capacity of the former was 126.52F/g,while that of the latter was 108.02F/g.(4)The specific capacity of phenol based activated carbon was similar to pitch based activated carbon powder at lower charge-discharge current,with the same BET and particle size.However,the former's was higher at higher the charge-discharge current,At 1 mA charge-discharge current,the specific capacity of both were about 105F/g,however,at 50 mA charge-discharge current,the specific capacity of the former was 41.94F/g,that of the latter,17.23F/g.