Research On The Performance Of Organic Supercapacitors

Supercapacitor is a new-type energy storage equipment between chemical battery and static capacitor, it can be divided into two type according to its electrolyte: water system and no water system. Organic supercapacitor belongs to no water system, its electrolyte is organic solution. Most of it are electric double-layer capacitor, their electrode contains almost carbon material. supercapacitor in this experiment is also belong to this kind.A series of experiments were conducted to research on capacitor unit and its electrode with the aids of measurement such as cyclic voltammetric, impedance spectrum, constant charge/discharge testing, equivalent Series resistance(ESR) measurement and so on. The ideal results of those method are also analyzed. we found that activated carbon(AC) in our experiment displayed electric capacity characteristic in lmol/L LiPF₆/EC+ DMC solution,using nickel foam as current collection, the capacitor unit made by it has a ESR of about 3Ω ,discharge specific capacitance is 22.1F/g with a current density of 5mA/cm² , but its circulation performance remains to be improved. After using 65% nitric acid and 98% sulphuric acids to active this AC, we found the specific capacitance improved a lot, but leakage current and ESR increased too. Activated by 10% ammonia water caused the capacitance decrease. With 20Mpa pressure and 20mg/cm2 carbon clarifying capability , the electrode consists of 5% acetylene black and 5% PTFE has its best property,. Measured by silver metal quasi- reference electrode, the mono electrode capacitance can reach 102F/g, and ESR is about 0.9Ω. makes up single electric capacity It is 23 than the capacity. 13F/g. we also investigated the performance of AC in lmol/L LiClO₄/PC and solution , testing results show that in LiClO/AN the capacitor has the lowest ESR of about 1.4Ω ,and capacitance is as better as in LiPF₆/EC + DMC solution, in LiClO₄/PC the capacitor has good ability in voltage sustainand circulation performance, both of the two electrolyte has its advantage and shortage ,the equal volume mixture of them has a good conductivity .After we utilizing the mixture in double-layer we came to theconclusion that the mixture electrolyte is suitable for supercapacitor. Because using foam nickel as current collection limits the voltage of organic supercapacitor only about 2V, so experiment with aluminium foil as electrode current collection is also to be studied, After carrying a large amount of exploration to the technician of making electrode, the results show that in the condition of 120 degrees dried,3Mpa treated and with the mass ratio of about 89:6:5(activated carbon: PvdF: acetylene black), the electrode material can be well combined with aluminium foil, composed of these electrodes, the capacitor can work in the voltage of above 3 V , but specific capacitance is only about 17. 54F/g, ESR is about 10 Q ,so it is not suitable for the heavy current discharge, there are still have something to do to improve the performance.