Pseudocapacitive ferromagnetic polypyrrole – La0.8Sr0.2MnO3 composites

Abstract

1-Diazo-2-naphthol-4-sulfonic acid (DNS), and sodium taurocholate (ST) are used as new anionic dopants-dispersants for the fabrication of polypyrrole (PPy) supercapacitor electrodes. The electrodes show ideal pseudocapacitive behavior with capacitances of 4.89 and 4.77 F cm−2 for DNS and ST, respectively. Composites with high active mass of 40 mg cm−2 containing ferromagnetic La0.8Sr0.2MnO3 (LSM) and conductive PPy are obtained. The approach of this investigation eliminates the problems of previous works on PPy-LSM composites related to the use of negative potential window and alkaline electrolyte. In contrast to previous works, the electrodes showed nearly ideal pseudocapacitive behavior in a neutral Na2SO4 electrolyte. Moreover, the composite electrodes showed significantly higher capacitances of 2.82 and 2.60 F cm−2 for DNS and ST, respectively, and enhanced capacitance retention at high charging rates. The composites combine advanced pseudocapacitive properties of PPy with high magnetization of ferromagnetic LSM.