A novel perspective on interfacial interactions between polypyrrole and carbon materials for improving performance of supercapacitors

Using carbon-based materials as substrates or additives is an effective strategy for the improvement of electrochemical properties of polypyrrole (PPy) in supercapacitors, while the interfacial interactions between them is not exactly clear, which limits the rational design of composite electrodes. Herein, the interfacial interactions are investigated by forming novel freestanding composite electrodes via depositing PPy on the surface of carbon foam (CF). After combination, the capacitance increases from 37.3 mF cm−2 to 364.0 mF cm−2. Moreover, a superior capacitance retention (99.6%) can be achieved, after 10,000 charging/discharging cycles. Density functional theory (DFT) results show that the introduction of different oxygen-containing functional groups will lead to the difference of adsorption energy between carbon materials and PPy, thus affecting the cycling stability of composite materials. Moreover, the intermolecular interaction also affects redox properties of composite electrodes by changing the composition and energy of frontier orbits of the interfacial complexes involved in redox reactions. This study will provide a new perspective for purposeful regulating the electrochemical performance of composite electrodes.