Improvement In Pseudocapacitance For Carbon Cloth Based Supercapacitor

As the growth of economic and population,the appetite for energy become more and more voracious.Fossil fuel,tradition energy,become exhausted.Supercapacitor,with superlong cyclic life and short charging and discharging time,is highly anticipated as one of promising new energy storage systems.Meanwhile,scientists and enterprises have an increasing focus on flexible devices.Carbon cloth,with merits of inherent mechanical flexibility,light and easy to assemble,is likely to assemble to flexible supercapacitor.However,carbon cloth based supercapacitor is functioned with electric double-layer capacitor,which is unsatisfactory compared to pseudocapacitance.One of the challenage for commercializing carbon cloth based supercapacitor is that how to improve the pseudocapacitance of flexible supercapacitor.Considering the problem that improve the pseudocapacitance of carbon cloth based supercapacitor,the first part of thesis successfully synthesizes NH4V4O10@TCC1000 with activated carbon cloth as substrate and NH4VO3 as the source of vanadium.By adjusting and controlling the hydrothermal time,we get the optimal complex electrode.At the same time,we investigate the structure and morphology for samples.Select the sample,whose hydrothermal time is 24 h,as anode,cathode and anode/cathode,for assembling solid-state supercapacitor.Solid-state NH4V4O10|TCC1000||TCC1000|NH4V4O10 with the best performance is in possession of a areal capacitance of 1313 1F cm-2 and a maximum energy density of 0.59 mW h cm'2,which is 1.3 times to TCC1000||TCC1000.Besides,100%capacitance retention was achieved over 25000 cycles.Aferwards,in the second part,we improve the pseudocapacitance of carbon cloth based supercapacitor by modifying the capability of electrolyte.Firstly,the carbon cloth is annealed and become porous.By study of the change of surface group and specific surface area for carbon cloth annealed at different temperature.,we find the rules:with O-doped in the treated carbon clothes,the operated voltage window can be extent to 1.8 V by suppressing the HER;the high surface area can enhance the electric double layer capacitance.After selecting the optical electrode,solution-casting method is used to introduce methylene blue to acid electrolyte for improving pseudocapacitance of supercapacitor.Methylene blue not only provides pseudocapacitance by fast faradic reactions but also promotes ion conductivity of electrolyte.Through investigating the impact between concentration of methylene blue and capacitance,we obtain the best addition quantity.the device exhibited a high capacitance of 1738 mF cm-2 and a maximum energy density of 0.78 mW h cm-2,which is 0.6 time higher than the original.Only 15.4%decay in capacitance was observed after 8000 cycles,which is better than the original(28.2%).In all,we get NH4V4Oio@TCC1000 by hydrothermal and introduce MB to electrolyte,which both efficiently enhance the pseudocapacitance of carbon cloth based supercapacitor.The as-assembled solid-state supercapacitors not only possess the EDLC capability of carbon based supercapacitor,but also Faradic reaction of battery,which are novel and efficient hybrid supercapacitors.Moreover,facile and economic strategy in operation benefit to commercial manufacturing for enhanced carbon cloth based supercapacitors.