Preparation optimization on the coating-type polypyrrole/carbon nanotube composite electrode for capacitive deionization

In order to obtain the high electrode performance in capacitive deionization (CDI), the coating methodology was introduced and incorporated in the fabrication of the novel polypyrrole/carbon nanotube (PPy/CNT) composite electrode. A typical optimization on the major preparation parameters of the coating-type PPy/CNT electrode was conducted, including the mass ratio of electrode material mixture, the coating thickness and the drying temperature. Based on the PPy/CNT composite, the performance of the optimized coated electrode and the compressed electrode was typically compared in terms of the electrochemical characteristic and desalination performance. The experimental results indicated that the performance of the coated electrode got to the optimum under the mass ratio of 8:1:1 for the PPy/CNT, polyvinylidene fluoride and graphite, the coating thickness of 0.3 mm and the drying temperature of 40 °C. The coated electrode was markedly superior to the traditional compressed electrode in terms of the specific mass capacitance and specific adsorption capacity. The specific mass capacitance and specific adsorption capacity of the coated electrode reached 180.61 F/g and 93.68 mg/g respectively, which were 1.57 and 1.37 times that of the compressed electrode. These conclusions would lay a good foundation for the practical application of the coating methodology and also the novel electrode composite materials in the CDI field.