High capacitance of polypyrrole hydrogel electrode synthesized by polymerization of conjugated pyrrole salt

Fabrication of electrode materials with high capacitance is crucial for their application in supercapacitor. In this paper, a novel “polymerization of conjugated pyrrole(PY) salt” strategy, namely mixing ammonium auritricarboxylate (ATA) and PY to form conjugated ATA-PY salt firstly and later polymerizing that salt by chemical oxidation, is developed to synthesize polypyrrole (PPY) hydrogel. For the product noted as PPY/ATA hydrogel, the successful doping by a conjugated polyacid originating from ATA, results in the enhanced electrical conductivity and thus the capacity is increased sharply. Specifically, at the mole ratio of 1/1000 (Mpyrrole/MATA), the as-prepared hydrogel electrode displays the highest conductivity (σ =10.1 S/cm) and its specific capacitance 0.2 A/g of electrical current can get up to 1209 F/g in three-electrode measurement, which is 2.2 times higher than that of pristine PPY (540 F/g) and is the most prominent in the reported PPY hydrogels so far. Besides, it can also display the excellent specific capacitance of 680 F/g (1020 F/cm2) in the two-electrode system. Those results can make our product found potential application in supercapacitor and demonstrate the notable progress of PPY-based materials.