The Use of Conductive Polymer Composite to Enhance the Cyclic Life of Energy Storage Devices

Abstract

Energy is critical to promoting progress and sustainability in all aspects of life. The global energy demand is rapidly increasing, posing a significant challenge, particularly in Pakistan. Renewable and non-traditional energy sources offer a viable solution to this problem. Solar energy, wind energy, and hydropower are all feasible alternatives to traditional energy sources. Energy storage batteries are rechargeable and designed to catch and store energy. They are composed of positive and negative electrodes, separators, and suitable electrolytes. Addressing the challenge of limited cycle life in traditional lead-acid batteries characterized by rapid capacity decline due to lead sulfate crystallization and interfacial instabilit poses a sustainability issue in energy-scarce regions like Pakistan. This research developed a conductive polymer composite using reduced graphene oxide-copper-doped polyacetylene-co-polyaniline (rGO-Cu-PA-co PANI) blended with reduced graphene oxide (rGO), synthesised via a solution-assisted dispersion method that incorporates rGO as a conductive support matrix to enhance electron transport. Polyacetylene (PA) and polyaniline (PANI) serve as redox-active polymers, offering tailorable pseudocapacitance. Copper powder is used as a dopant to enhance electrical conductivity and catalytic activity, while sulfonated polysulfone/PVDF serves as a binder to ensure mechanical stability. Material characterisation through FTIR spectroscopy confirmed molecular integration with distinct peaks such as N–H stretching at 3281 cm⁻¹ (indicating the PANI backbone), C=C bonds at 1643 cm⁻¹ (indicating PA conjugation), C–N sulfonic groups at 1061 cm⁻¹ (indicating covalent functionalisation), and C–H bending at 748 cm⁻¹ (representing PVDF). XRD analysis revealed a semi-crystalline structure with broad reflections at the (200) planes for PA/PANI and (110,111) planes for copper, contrasting notably with the brittle, highly crystalline state of unmodified lead oxide. Electrochemical testing showed impressive performance; cyclic voltammetry indicated more than double the anodic and cathodic currents and broader redox peaks compared ix to PbO at 50 mV/s, confirming enhanced pseudocapacitance, with stability maintained at higher scan rates (80–100 mV/s). EIS Nyquist plots exhibited lower charge-transfer resistance and significant capacitive behaviour, while cycling tests achieved an outstanding 70% capacity retention after 6,000 deep discharge cycles doubling the lifespan of unmodified electrodes, which retained only 35% after 500 cycles. This durability is attributed to the composite's ability to reduce lead sulfate crystallisation by promoting uniform charge distribution, suppressing hydrogen evolution, and decreasing ionic resistance through improved electrolyte wettability due to the sulfonated groups. Furthermore, the rGO framework prevents polymer chain scission, while copper doping encourages electron hopping across the electrode. Collectively, these features demonstrate that conductive polymer composites offer a scalable strategy to enhance cycle life, increase charge acceptance, and extend operational longevity by a factor of 12 in lead-acid batteries for renewable energy grids and electric vehicles.