One-step electrosynthesis of polypyrrole/PbO_x composite in acetonitrile as supercapacitor electrode material

This study explores the single step electrochemical synthesis of polypyrrole/PbO_x composite on the Pb-intercalated (intc.) graphite electrode in acetonitrile medium, including Py, TBABF₄, HBF₄, H₂O, Pb(BF₄)₂, TX100 and carboxymethyl cellulose. The coatings on Pb-intc. graphite surface are analyzed by SEM-EDX, BET, TEM, XPS, and XRD techniques. The effects of the additives on the capacitive properties are investigated electrochemically in an H₂SO₄/water medium. PbO_x and carboxymethyl cellulose enhance the specific capacitance and the cyclic stability. Although the amount of PbO_x in the composite is low (1.2% atomic percentage of Pb), it contributes significantly to the specific capacitance due to the homogenous distribution of PbO_x in nanostructures. The amount of specific capacitance of the composite film (4.0 mg cm⁻² loading) on the Pb-intc. pencil graphite is calculated as 377 F.g⁻¹ at 2.0 A.g⁻¹ in 100 mM H₂SO₄ by subtracting that of bare graphite. The two electrode cells (asymmetric and symmetric) are constructed using Teflon Swagelok in polyvinyl alcohol/H₂SO₄ gel electrolyte. In the symmetric supercapacitor configuration, the composite coating (10 mg cm^-2 loading) on Pb-intc. graphite paper electrode has 0.29 kW kg⁻¹ and 22 Wh. kg⁻¹ at 0.5 A g⁻¹. The results also indicate a good cycle performance (94% after 5000 cycles) in the potential range of 0.8 V.