Research Of Hybrid Supercapacitors With Gel Polymer Electrolytes

Electrochemical supercapacitor is a new energy storage equipment and component between electrostatic capacitors and batteries, which has higher energy density than that of electrostatic capacitor and higher power density than that of batteries. When working with batteries, they can meet the high power out-put need of electric vehicles when starting-up or accelerating. It can also be used in many fields such as hybrid electric vehicle, fuel cell and microcomputer etc. It's of great importance to research on related aspect of supercapacitors such as electrode materials, electrolytes.In this paper, a series of experiments were conducted to research on electrode materials, electrolyte with the aids of the measure methods such as cyclic voltammetric measurements(CV), constant charge/discharge measurements, impedance spectrum, X-rays diffraction(XRD)and so on. The results came as follows. The electrochemical performance of hybrid capacitor in organic electrolyte was studied, the results showed MnCVAC capacitors which had a better performance in 1.0mol/L LiPF₆/EC+DMC could provide a specific capacitance of 53.17F/g when the ratio of MnO₂ in the positive electrode and AC in the negative was 1:1.13. And the working voltage of hybrid capacitor can reach 2.5V. MnO₂ was synthesized by liquid-phase reaction as positive electrode, Polyacrylonitrile(PAN) based gel polymer electrolytes MnCVAC hybrid capacitors were fabricated by an in situ polymerization method. the results showed that the conductivity of the gel polymer electrolyte can reach 8.92 mS/cm, when activated carbon (1000m²/g) was used as negative electrode, the specific capacitance of the supercapacitor is 27.3F/g and is 48.21% higher than that of AC/AC capacitor. When activated carbon (2600m²/g) was used as negative electrode, the specific capacitance of the supercapacitor is 37.18F/g. MnO₂ was modified by AC, hybrid capacitor which composite electrode and activated carbon electrode were used as positive electrode and negative electrode, could provide a specific capacitance of 41.57F/g when the content of AC was 60% in the composite, which was 42.4% higher than that of MnCVAC capacitor and the circulation performance had a certain improvement. PMMA- based gel polymer electrolytes MnCVAC capacitors were fabricated by an in situ polymerization method with MnO₂ as positive electrode and activated carbon as negative electrode, the results showed that when the content of MMA is 20%, the conductivity of the gel polymer electrolyte can reach 6.1 mS/cm, the capacitance is 34.02F/g and the working voltage of hybrid capacitor can reach 2.8V.