Electrochemical synthesis of PPy composites with nanostructured MnOx, CoOx, NiOx, and FeOx in acetonitrile for supercapacitor applications

Abstract

In the present study, the polypyrrole (PPy) composites with nano-structured CoOx, NiOx, MnOx, and FeOx were synthesized using the galvanostatic method on their own metal-intercalated graphite surfaces. The deposition and intercalation are performed in TBABF4/acetonitrile solution with related metal (II) tetrafluoroborate salts, pyrrole, HBF4, H2O, Triton-X 100 (TX100) and carboxymethyl cellulose (Na-CMC). For the PPy/MnOx/Na-CMC composite, the effects of intercalation and additives on the specific capacitance were examined in an H2SO4/water medium by using cyclic voltammetry (CV) and the Electrochemical Impedance Spectroscopy (EIS). Using the optimum deposition conditions determined for Mn composite (additive concentrations and galvanostatic parameters), PPy/CoOx/Na-CMC, PPy/NiOx/Na-CMC, and PPy/FeOx/Na-CMC coatings with a mass loading of 4.0 mg cm−2 were deposited on their own metal-intercalated graphite electrodes in the deposition solutions containing Co(BF4)2, Ni(BF4)2 and Fe(BF4)2, respectively. XRD, TEM, XPS, SEM-EDX, BET, and EIS techniques were used in characterizing the coatings. Subsequently, the capacitive properties of the composite coatings were examined by means of the galvanostatic charge-discharge test. The highest SC value is recorded for the Mn-based composite (463 F g−1), whereas the lowest is for Fe-based (311 F g−1) one. Finally, symmetric and asymmetric supercapacitor configurations incorporating two electrodes with 10 mg cm−2 active material were used in making measurements to determine the capacitive behaviors of PPy/Metal oxide composites. The symmetric supercapacitor with PPy/MnOx/Na-CMC composite providing 0.29 kW kg−1 and 15.0 Wh.kg−1 at 0.5 A g−1 maintains 62% of its power and energy densities at 2.5 A g−1 at the end of 5000 cycles at a potential range of 0.8 V.