Preparation Of PAN Quaternary Ammonium Salt Gel Polymer Electrolyte And Its Application In Supercapacitors

A supercapacitor is mainly composed of electrode material, current collector,separator and electrolyte. As an important part of a supercapacitor, electrolyte is an extremely important research area. Different types of electrolyte often have a great impact on the performance of supercapacitors. Supercapacitors of gel polymer electrolyte are safe and leak-free, and can adapt to the development of minitype and super-thin electrical equipment.Quaternary ammonium salt products are green, environment-friendly, readily biodegradable, and free of APEO, formaldehyde or other substances that may endanger the natural environment and human health. With increasing public awareness and environmental quality requirements, these products continue to meet the needs of social development. Moreover, the raw materials of the electrolyte composed of quaternary ammonium salts are readily available, and the production process is simple. Therefore, the electrolyte composed of quaternary ammonium salts is an ideal future direction for gel polymer electrolyte.Three different types of gel polymer electrolyte composed of polyacrylonitrile?PAN?-based quaternary ammonium salts were prepared by using PAN as polymer matrix, three quaternary ammonium salts of different structures including TEABF₄,SBPBF₄ and SBPBOB as electrolyte salt, and dimethyl sulfoxide?DMSO? as plasticizer, and the prepared gel polymer electrolytes were assembled respectively to simulate supercapacitors. The electrochemical properties of the gel polymer electrolytes were tested by using electrochemical impedance spectroscopy?EIS?,cyclic voltammetry?CV?, galvanostatic charge-discharge?GCD? and other electrochemical testing methods and characterized by IR-TR and DG-DTG.PAN/TEABF₄ gel polymer electrolyte had the minimum body resistance Rb and the maximum conductivity. The electrochemical stable windows of PAN/TEABF₄,PAN/SBPBF₄, PAN/SBPBOB gel polymer electrolytes were 2.7,2.6,2.5V,respectively. PAN/TEABF₄ gel polymer electrolyte had the best overall performance,with specific capacitance up to 27.59 F/g, energy density up to 100.575 J/g, and power density of 0.675 KW/Kg, and it had the longest cycle life. The infrared spectroscopy shows that PAN and TEABF₄ are well combined and maintain the original molecular structure, and that the reaction of SBPBF₄ and SBPBOB has an obvious impact on PAN structure. The TG-DTG shows that the gel polymer electrolyte composed of PAN-based quaternary ammonium salts has good thermal stability.Then, according to the above it is concluded that the best is TEABF₄. Then specifically discusses the quality of TEABF₄ and PAN proportion, let stand for time and inorganic additives SiO₂ to add quality affect the performance of PAN/TEABF₄ gel polymer electrolyte. It is concluded that amount of PAN/TEABF₄ gel polymer electrolyte conductivity, specific capacitance and energy density and power density were increased, but after reaching a certain degree, with the increase of the electrolyte salt TEABF₄ adding, the PAN/TEABF₄ gel polymer electrolyte electrochemical comprehensive performance declines, TEABF₄ and PAN best quality ratio is mTEABF₄ / mPAN = 0.5. With the increase of standing time PAN/TEABF₄ gel polymer electrolyte electrochemical properties firstly is increase then dropping, preparationed PAN/TEABF₄ gel polymer electrolyte's best to let stand in 60 h, In PAN/TEABF₄ gel polymer electrolyte with the increase of inorganic additives SiO₂ added quality, PAN/TEABF₄/ SiO₂ gel polymer electrolyte conductivity, specific capacitance and energy density and power density were increased, but after reaching a certain degree, with the increase of SiO₂ content PAN/TEABF₄/SiO₂ gel polymer electrolyte electrochemical comprehensive performance declines, when the quality of SiO₂ is about 6.25%..PAN/TEABF₄/SiO₂ gel polymer electrolyte best specific capacitance of 33.05 F/g, charging and discharging efficiency was 88.6%, the energy density of148.70 J/g and power density of 0.750 KW/Kg. And PAN/TEABF₄/ SiO₂ gel polymer electrolyte electrochemical stability is very good, has the very good application value.