Manufacturing of polypyrrole-FeOOH supercapacitors

The low capacitance of charge storage materials for negative electrodes of supercapacitors (SCap) is a bottleneck in the manufacturing of asymmetric SCap with high operation voltage and high power. Polypyrrole (PPR)-FeOOH-carbon nanotube (NT) electrodes with high electrochemically active material mass (AM) of 32 mg cm−2 are manufactured for operation in a negative potential range. The manufacturing method involves the use of copolymer of styrenesulfonic and maleic acids (PSAMA) as a new poly-charged dopant for PPR and pyrocatechol violet (PCV) as a co-dispersant for NT and FeOOH. PPR-FeOOH-NT electrodes show enhanced properties in the negative potential range, compared to PPR-NT electrodes. A capacitance (CS) of 3.8 F cm−2 is obtained for PPR-FeOOH-NT electrodes with PPR:FeOOH mass ratio of 7:2. The electrodes offer advantages of low resistance and high ratio of AM to conductive support mass. The CS of negative PPR-FeOOH-NT electrodes matches the CS of positive MnO2-NT electrodes of the same AM. Asymmetric SCap is fabricated, which shows high capacitance in a voltage range of 0–1.6 V and low resistance, high power, and energy, which make it important for industrial SCap applications.