Investigation Of The Preparation And Characterizarion Of Button Supercapacitor Electrode

Supercapacitor is an electric storage device which stored electric charge based on electric double layer mechanism and pseudocapacotance mechanism. Supercapacitor is widely used in green energy, military system, back-up electrical power system and so on. It is well known that active materials like activated carbon(AC) and conducting polymer(CP) have excellent electrochemical performance. This dissertation focuses on the preparation of activated carbon(AC), conducting polymer and their composites as button supercapacitor electrodes. The main works include preparing and process optimization of button supercapacitor electrodes, selection of conductive agent in electrodes and the preparation and characterization of polymer-AC composite electrode. The main works are as follows:1. The influnec of conductive agents acetylene black, conductive graphite and superp on performance of supercapacitor electrodes was investigated and the proper conductive agent was adopted based on the results. It has been found that the electrode utilizing acetylene black as conductive anent showed best electrochemical performance. This electrode exhibited high specific capacitance about(81F/g), low equivalent resistance(5.32?), and maintained excellent capacitance retention(74 F/g) after 1000 times cycling.2. The button supercapacitor electrodes based on conducting polymer poly 3,4-ethylenedioxythiophene(PEDOT) and polypyrrole(PPY) were fabricated and the related electrochemical performance were investigated. The results indicated that the capacitors based on pure PEDOT and PPY both exhibited poor electrochemical perforamce, and showed low specific capacitance about 10F/g and 40F/g respectively at a 1A/g current density. The BET and BJT testing revealed that the unordered distribution of holes was consutrcted in these electrode films, resulting in poor matching performance between polymer electrode and electrolytes. The further investigation reveal that the agglomerate of conducting polymer during the charging/discharging process also leads to the degradation of electrochemical performance.3. A high-speed agate beads milling process was utilized to prepared PEDOT-AC and PPY-AC composite electrodes. The testing results indicate that the contents of polymer in composite electrodes showed distinct influence on electrochemical perfoarmce of composite elelctodes. The PEDOT-AC and PPY-AC composite electrodes showed 124F/g and 160F/g as highest specific capacitance respectively. The BET testing confirms that uniform distribution of hole structure was constructed in electrode films, which results in fast adsorption/desorption of electrolytic ion on and from the electrode surface.