The Preparation Of Carbon-based Composite Electrode Material In Flow Battery And Study Of Surface Modification Of Anode

To improve charge-discharge efficiency and cycle life of the methyl sulfonic acid lead flow battery as the goal,this paper had prepared a series of composite conductive plate in which flake graphite(GP)and conductive carbon black(CB)were main conductive filler,high density polyethylene was used as binder and chopped carbon fiber functioned as flexibility-enhanced material.The composite electrode prepared by components in different ratios was studied on its bending strength,conductivity,corrosion resistance and charge-discharge efficiency.Meanwhile,to improve the binding property which PbO2 sediments and carbon-based anode,added cavernous surface modification of graphite felt to enhance the specific surface area for solid-liquid interface of anode,reached to strengthen PbO2 deposition effected on the anode.The influence of surface modification on the battery efficiency and cycle life were characterization by using Infrared spectrometer,scanning electron microscopy,electrochemical workstation and charge-discharge test system.The result showed:Primarily,this paper had investigated systemically the technological parameter which included molding temperature and pressure,component parameters including high density polyethylene(HDPE),chopped carbon fiber,flake graphite and conductive carbon black effected on carbon-based composite electrode material's bending strength,conductivity,corrosion resistance and charge-discharge efficiency.The researches showed:(1)Improve the mold temperature or increase the mould pressure can ameliorate bending strength of carbon-based composite electrode,the mold temperature were 180 degrees Celsius and mold pressure reached to 20 MPa,bending strength of carbon-based composite electrode can satisfy performance of 50 MPa for flow battery;(2)adding HDPE content from 23wt% to 31wt%,bending strength of the composite increased monotonous regularity,whereas its conductivity with the increase of the resin content is on the decline.HDPE content with 27 wt% of composite not merely demanded the 50 MPa bending property of carbon filler/polymer bipolar plate by USA DOE,also maintain high conductivity;(3)bending strength and conductivity firstly increased then decreased as chopped carbon fiber increased,inflexion point occurred chopped carbon fiber(CF)content 4wt%;(4)GP and CB mass proportion from 3:1 to 6:1 in condition of same content HDPE and chopped carbon fiber,bending strength and corrosion resistance were weaken,simultaneously conductivity increased then decreased.By optimizing the experimental parameters,GP and CB mass proportion was 5:1,the conductivity can reach 12.34 s/cm,the bending strength is up to 50.29 MPa,corrosion rate to 0.24 mm/year;(5)the battery with composite material of GP wt%:CB wt% was 5:1 by charge-discharge test showed that the energy efficiency of charge-discharge test reached almost 78% reported to the highest level on the condition of continuous charging and discharging 1000 times,3700 h.Secondly,the surface of the graphite felt(GF)was disposed by sulfuric acid oxidation and thermal oxidation in air,the numbers of-COOH and-C=O oxidation of hydrophilic functional groups on the surface of GF were obviously increased by soaking duration 5h in the 98% content sulfuric acid and high-temperature oxidation treatment duration 12 h in 500 degrees Celsius,electrode interface of GF enhanced the adsorption of Pb2 + in electrolyte,surface of GF with sulfuric acid produced etching phenomenon,leading to enlarge the surface of GF;the flow battery with solid-liquid interface of anode contained disposed surface of GF by charge-discharge test revealed the energy efficiency reached 87%,9% higher than the battery without disposed surface of GF.