Preparation and electrochemical stability of graphene/polyaniline composites with polylactic acid as biodegradable adhesive

Conductive polymer polyaniline (PANI) is a hot research topic in pseudocapacitor electrode materials due to its low preparation cost and high specific capacitance. In this work, graphene/polyaniline composites (Gr/PANI) were prepared by in situ chemical oxidation polymerization. The morphology and structure of the materials were characterized by SEM, TEM, EDS, XRD and FTIR. Additionally, Gr/PANI capacitors were prepared using PLA and PVDF as adhesives, and the electrochemical behavior was studied by galvanostrotic charge–discharge (GCD) and cyclic voltamphe (CV). Furthermore, the 500 cycle stability and the degradation of PLA on capacitance performance of 90 days were carried out in both acidic and neutral solutions. Results show that the specific capacitance of PANI compounded with 50 mg graphene (P-50) is higher than that of pure PANI at current density of 0.5 A/g. Electrode has higher specific capacitance and better cycle stability in acidic solution than in neutral solution. The specific capacitance of P-50 + PLA is 332.3 F/g in sulfuric acid solution, which is 37.4% higher than that of 241.8 F/g in sodium sulfate solution. The cycle stability show that capacitance retention of P-50 + PLA (71.1% content) was 14.4% less than that of P-50 + PVDF (85.5%) after 500 number cycles. Degradation of PLA on capacitance studies show that the capacitor (P-50 + PLA) displays relatively stable adhesion performance within 20 days in acidic solution and performs stable adhesion property within 90 days in neutral solution. It reveals that the PLA may be used in energy storage devices as environmental-friendly adhesive.