Electric Double Layer Capacitor:Electrode Material,Preparation Process And Performance

Abstract:Electrical double layer capacitor (EDLC), also called supercapacitor, can discharge with great pulse current and its’life is nearly semi-permanent, and it may becomes a new type, efficient and practical energy storage device in the future. At present, the domestic companies are still fall behind with the preparation process of EDLC slurry and pole piece. Slurry preparation parameters and compaction pressure on the performance of EDLC were studied basing on research of three electrode materials (binder, conductive agent, activated carbon). And small cylindrical capacitor and the large rectangular capacitor were prepared under the condition of laboratory, and their electrochemical performances were studied. Experiments show that:1) Using LA133as adhesive can get larger specific capacitance and smaller equivalent series resistance (ESR) than PTFE. Using5%multilayer graphene as conductive agent can get larger specific capacitance and smaller ESR, and increase the content of activated carbon comparing with10%carbon black. The specific capacitance of activated carbon increasing trend is slowed down when their specific surface area are more than1600m2/g. The discharge characteristic of mesoporous carbon is better than the microporous carbon. Activated carbon can get better discharge characteristics when its’mesoporous content is more than21%.2) The optimal slurry ratio composition parameters is10%carbon black content, the binder composed of1.5%CMC,1.5%LA135,6%LA133and2%SBR, and slurry liquid-solid ratio of2.8:1. With the optimal slurry ratio composition, the specific capacitance is114.6F/g and ESR is1.18Ω. at the discharge current of0.15A/g.3) The best compaction pressure is35MPa after studying effect of compaction pressure on organization performance of EDLC. When the compaction pressure is35MPa, the compression ratio is16.2%, the ESR is0.92Ω that is the minimum, and the specific capacitance is118.3F/g at the current density of0.15A/g. The attenuation of specific capacitance is only4.5%when the current density increases from0.15A/g to9.6A/g. The mass energy density is6.36W·h/kg, the volumetric energy density is7.27W·h/L, and the power density is14.2kW/kg.4) The capacitance of10F/2.7V EDLC only decreases by1.1%when the current increases from0.2A to1.6A, and the capacity is still as high as15.10F at the discharge current of1.6A. Its’leakage current is less than0.1Ma, and its’capacitance is not decayed after2000cycles. The capacitance of3500F/2.7V EDLC is3833F at the discharge current of5A, the ESR is0.2mΩ, the mass energy density is4.34W·h/kg, the volumetric energy density is5.32W-h/L, and the power density is10.18kW/kg. Its’ capacitance only reduce3.0%when the current increases from5A to20A, and its’leakage current is about55mA. The attenuation of capacitance is only0.12%after500cycles.