Preparation Of Function Ionic Liquids/Polyaniline Composite Electrode Materials And Their Capacitance Properties

Supercapacitor as a new kind of green energy storage device, and with high specific capacitance, shortcharging time,wide operating temperature range,long cycle life, high power density,environmentally friendly and many other advantageshas been attractedthe attention of researchers. Electrode material is one of the important factors affecting the capacitanceperformanceof the supercapacitor. From the perspective of analysis of the material, the electrode materials of supercapacitors can be divided into three categories: carbon materials, metal oxide materials, conductive polymer materials. Conducting polymersare more and more attractive because they can provide higher charge density, low cost, environmentally friendly, easy to prepare. Currently, PANI has generated considerable interest owing to its low cost, good environmental stability, high conductivity, favorable thermostability,as well as easy modification by changing the oxidation states and protonation states.Therefore, PANI has been considered as one of the most promising conducting polymers and has been widely used in many fields. Recently, PANI was found that the microstructure plays a critical influence on the capacitance performance of PANI.Ionic liquids(ILs) have become one of the fastest growing “green” media because of their excellent properties, such as non-flammable, vanishingly low vapor pressure, excellent chemical and thermal stability, high ionic conductivity, polarity tunability broad electrochemical windows.In view of their higher decomposition potential and chemical stability, ILs have been proved to be promising electrolyte for electrochemistry,as well as supercapacitors. In this paper, we prepared conductive polymer composite electrode materials via in-situ oxidation polymerization with function ionic liquids doped polyaniline. And morphology, structure and electrochemical properties of the electrode material prepared was studied. This paper further study the effects of ionic liquid with different alkyl chain on conductive polymer morphology and thus affect the capacitor performance. The main contents include the following:1.Preparation of the ionic liquid monomers containing different compositions and structures, include 1- methyl- 3- carboxymethylimidazole chloride ionic liquid, 1- vinyl- 3- carboxymethylimidazole chloride ionic liquid, 1- butyl- 3-carboxymethylimidazole chloride ionic liquid, 1- hexyl- 3- carboxymethylimidazole chloride ionic liquid, and these were characterized using 1H-NMR and 13C-NMR and their melting points were also measured respectively.2. Preparation of the PANI was doped by the as-prepared functional ILs via in situ chemical oxidation polymerization. The morphology and structure of this electrode materials were characterized by FT-IR, SEM and XPS. Their electrochemical performance were investigated by cyclic voltammetry and galvanostatic charge/discharge. Among the as-prepared ILs, 1-vinyl-3-carboxymethyl-imidazole chloride([VCMIm]Cl)@PANI electrode materials with [IL]/[An] molar ratio of 1:1 presented the highest specific capacitance(624 F g-1 at the current density of 1 A g-1). Cycling performance measurement indicated that 82% capacitance retention could be achieved after 1000 cycles.3.The carbon materials pyrolyzed in a ceramic crucible at 700?, 800?, or 900?for 2 h under an argon atmosphere, respectively. A heating rate of 5 C min-1was applied for the carbonization. The morphology and structure of this carbon materials were characterized by FT-IR, SEM and BET. Their electrochemical performance were investigated by cyclic voltammetry and galvanostatic charge/discharge. Feather carbonized at 800 C exhibited high charge storage capacity with a specific capacitance of 507.5 F g-1 at a current density of 1A g-1. Cycling performance measurement indicated that 94% capacitance retention could be achieved after 1000 cycles.