Synergy of Pseudocapacitive Properties of Ferromagnetic La1 − xSrxMnO3 and Polypyrrole in high Active Mass Composite Electrodes for Supercapacitors

This investigation is inspired by interest in magnetically ordered pseudocapacitive materials. Pseudocapacitive composites of La0.8Sr0.2MnO3 (LSM), polypyrrole (PPy) and carbon nanotubes are prepared. The electrochemical testing conditions for the composite electrodes are optimized for an active mass (AM) of 0.04 g cm− 2. Testing is performed in a sodium sulfate electrolyte in a potential range of– 0.5 to 0.4 V vs. SCE. The benefits of such composites are threefold. Firstly, the investigation of electrodes with different LSM and PPy contents reveals the synergistic contributions of LSM and PPy to the capacitance. Testing results show that significant capacitance enhancement can be achieved in the high AM composites. The best capacitance of 6.03 F cm− 2 (150.69 F g− 1) is obtained for composites containing 20% LSM. The composites show ideal pseudocapacitive behavior. Secondly, the composites show significant capacitance enhancement at fast charging conditions, which opens a door for improved devices. Thirdly, the synergy of LSM and PPy is manifested by significant reduction of electrode resistance and charge transfer resistance. Pseudocapacitive and magnetic characteristics of the electrodes can be varied. The mechanisms of synergetic effect of LSM and PPy on the electrode capacitance and enhanced LSM/PPy interface charge transfer are suggested. The approach proposed in this study offers a platform for manufacturing advanced magnetic pseudocapacitors with enhanced capacitive properties. The composite electrodes are utilized for the design of asymmetric devices, which show capacitances of 2.58 and 2.64 F cm− 2 from cyclic voltammetry and chronopotentiomentry testing results, respectively.Graphical Abstract