Investigations On Electrical Double Layer Capacitors Using Gel Polymer Electrolytes

Electrochemical supercapacitor which has higher energy density than that of electrostatic capacitor and higher power density than that of batteries is a new energy storage eqiupment and component between electrostatic capacitors and batteries. Supercapacitors with gel polymer electrolytes (GPE) , safer and more reliable than capacitors with aqueous electrolytes, are useful as power sources for hybrid electrical vehicles, for digital telecommunication systems, for communicators and pulse laser system. Now there are a few literaturs can be found both in Chinese and in other languages. So, it is meaningful to do research in this domain.In this disseration, poly acrylonitrile(PAN) based, poly methyl methacrylate(PMMA) based and poly acrylonitrile methyl methacrylate (P(MMA-AN)) based gel polymer electrolytes were synthesized. A mixtrure of propylene carbonate(PC) and ethylene carbonate(EC), dimetyl carbonate(DMC) and ethylene carbonate(EC), ethylmethylene carbonate(EMC) and ethylene carbonate(EC) were used as plasticizer,respectively. Lithium perchlorate was used as surporting electrolytes. The ionic conductivities of the electrolytes were evalued by impedance spectrum and its values can reach from 0.89mS/cm to 13.9mS/cm. The electrochemical windows of the electrolytes were evalued by cyclic voltammetry and its values can reach from 2.5V to 3.0V. PAN and PMMA based gel polymer electrolytes electrochemical double-layer capacitors (GPE-EDLCs) were also fabricated by "in situ polymerisatonal method" with actived carbon electrodes. The GPE-EDLCs properties were conformed by experiments of impedance spectrum, cyclic voltammetry, constant current charge/discharge. It showed that the working voltage of the PAN-based GPE-EDLCs reached to 2.5V and the PMMA-based GPE-EDLCs reached to 3.0V. The inner resistance and specific capacitance of the GPE-EDLC are similar to liquid organic electrolytes double layer capacitors(LOE-EDLCs).