Preparation And Charge Storage Performance Of Three-dimensional Self-supported Composites Based On Carbon Papers

Now the world is looking for new green energy in the situation with seriousenvironment pollution and energy shortage. Supercapacitors own vast applicationpromising because of quick charge/discharge rate, long cycle life, less environmentpollution, energy saving, low cost, and cause widely attention in the world. Thepreparation of electrode material is always the research center of supercapacitors.Carbon materials are always the research hot since its large specific surface area,excellent porous structure and good chemistry stability. For instance, the carbonnanotubes and graphite are favored by researchers because of its good conductivity,large specific surface area. But most of these activated carbon materials are preparedin the form of powder so that polymer binders are required for preparing the activatedcarbon electrodes, which limited its electrochemical performance. In order to furtherlow the production cost and increase the electroactive utilization ratio, it is necessaryto look for low cost and self-supported electrode material.The carbonized papers derived from filter papers after carbonization, not onlyshow advantage of low cost, simple preparation method and large scale production,but also keep its self-supported structure. This thesis used the carbonized papers assupport, via phosphate activation and low temperature air activation obtained twokinds activated carbon papers, respectively. And through aniline in-situ chemicalpolymerization obtained three-dimensional polyaniline/carbonized papers composites.Then study the effect of experiment conditions to its electrochemical performancesystematically.The specific works mainly include the following three parts:1. A series of activated carbon papers were prepared by carbonized paper (CP)which derived from filter paper (FP) carbonized at900℃after phosphate activation. Study the effect of different activation temperature and phosphate concentration to theelectrochemical capacitance performance of the carbonized papers, respectively.Experiment results exhibit that, when activation temperature is900℃and phosphateconcentration is0.3M, the activated carbon paper owns the best electrochemicalcapacitance performance. The specific capacitance reaches its high value243.9F/g atthe charge-discharge current density of0.5A/g, and still remains101.8F/g even whenthe charge-discharge current density reaches100A/g. After10000cycles at100A/g,its specific capacitance is stable without decrease.2. A series of activated carbon papers which carbonized at900℃of filter paperwere prepared by the air activation at different temperature(450℃,470℃,490℃).The results show that, when the activation temperature is490℃, the activated carbonpaper owns the highest specific capacitance317.9F/g at charge-discharge currentdensity of0.5A/g, but the specific capacitance only has75.7F/g at150A/g. However,when the activation temperature is470℃, though it owns a lower specific capacitance(296.4F/g), its specific capacitance can still keep66.2%(196.1F/g) at150A/g. After10000cycles at100A/g, its specific capacitance is stable without decrease.3. Polyaniline/carbonized papers were prepared by growing polyaniline (PANI)nanowires via in-situ chemical polymerization on the surface of CP. Experimentresults show that, the composites prepared under aniline concentration of0.01M andammonium persulfate concentration of0.0025M, sulfuric acid of1.5M has the bestmorphology and electrochemical capacitance performance. The specific capacitancereaches its highest value1090.8F/g at the charge-discharge current density of0.1A/g.When the charge-discharge current density expands100times, the specificcapacitance still remains386.9F/g. After10000cycles at10A/g, its specificcapacitance only decreases by16%.