Study On Coating Process And Performance Of PPy/CNT Composite Electrode

For the capacitive deionization (CDI) technology, it is very important to find theelectrode material with high adsorption capacity as well as to find a way to bring itsproperty into full play. So it is very significant to explore the molding technology ofthe electrode.In this paper, we firstly prepare polypyrrole/carbon nanotube (PPy/CNT)composites through chemical oxidation polymerizaton method. The PPy/CNTelectrodes are obtained by the compression method and the massa ratio of PPy/CNT,PVDF and graphite (G) is8:1:1. The specific capacitance of the obtained PPy/CNTelectrode is90.76F/g, which is3.0times and1.3times of the CNT and the PPyelectrode, respectively. The specific adsorption capacity of PPy/CNT electrode is90.16mg/g, which is6.28times and1.79times of the CNT and the PPy electrode,respectively. The PPy/CNTcomposites is stable under the potential of-0.4-0.8V (vs.SCE). The capacitance of PPy/CNTcomposites is diverse in different electrolyte,following: CaCl2>NaCl≈KCl>Na2SO4. The capacitance of PPy/CNT is very high inacid solution and decline quickly in alkaline solution.Select the activated carbon working as the active material of the electrode. weobtain the AC electrode with even surface and0.4mm coating through the coatingprocess using the “H” scraper, which PVDF serves as the binder, NMP (4.5g) servesas solvent and conductive graphite serves as the conductive agent (the massa ratio ofAC, PVDF and G is8:1:1). The specific surface capacitance and the specific surfaceadsorption capacity of the obtained AC electrode get to the maximum, which is0.2239F/cm2and0.5793mg/cm2. The hydrophilia of the AC electrode is improvedafter soaking in the mixed acid. The specific adsorption capacity and the specificsurface adsorption capacity of the AC electrode are1.81times and1.63times of theoriginal, respectively.PPy/CNT working as the active material of the electrode, we obtain the PPy/CNTelectrode through the coating process. Cracked phenomenon occurs during the coatingprocess, which is related to the evaporation of the solvent and can be avoided throughreducing the solvent volume, slowing the rate of the solvent evaporation and decreasethe drying time. The obtained PPy/CNT electrode which is coated with10%PVDF, 0.07g G,4g NMP and the graphite paper as the current collector and is dried in theair for12h have the best desalination results. The specific adsorption capacity and thespecific surface adsorption capacity of the obtained PPy/CNT electrode get to themaximum. The PPy/CNT electode obtained through the coating process show agreater advantage than the AC electrode obtained by the coating process and thePPy/CNT electode obtained through thecompression process.