Synthesis And Supercapacitive Properties Of The Three-dimensional Graphene-based Composites

Over recent years, an increasing rate of accelerating global energy consumption renders the development of sustainable energy conversion and storage technologies one of the priorities in the majority scientific advancement. Supercapacitors, with strengths such as excellent cycling stability, rapid charging-discharging rate and high power density, exhibit great prospects in the application of energy storage. Graphene-based composites combine the mechanisms of electric double layer capacitor (EDLC) and faradic pseudocapacitor, demonstrating strong potentials in the study of supercapacitor electrode materials.This thesis researches on two graphene-based aerogel composite-PANI (polyaniline)-graphene and MoS2 (molybdenum disulfide)-PANI-graphene-and carries on the thorough exploration in the following two aspects:1. Study of PANI-graphene binary aerogel composite as an electrode material. A facile cation-intercalation method was adopted to improve the composite morphology as to strengthen its electrochemical performance:GO (graphene oxide) was modified via the intercalation of divalent metal ions (Ni2+, Co2+, Cu2+, Mn2+) and then ultrasonically mixed with PANI. Afterwards the mixture was hydrothermally reduced and the final product was freezing-dried. Corresponding results demonstrated that the modification through the intercalation of cations could not only efficiently enhance the interlayer space of GO, but also optimize the particle size and distribution of PANI as well as the specific surface area. The phases of graphene and PANI were both proved. The modified binary composite material showed better electrochemical performance compared with that without any modifications, which included high specific capacity, rate capability and cycling stability.2. Study of MoS2-PANI-graphene ternary aerogel composite as an electrode material. A pre-dispersion treatment was adopted to enhance the compatibility of the composit so as to obtain a synergistic electrochemical performance:The MoS2 was hydrothermally synthesized followed by in situ polymerization with aniline to obtain MoS2-PANI composite. After being ultrasonically mixed with GO, the composite was hydrothermally reduced and the final product was freezing-dried. Corresponding results showed that the MoS2 displayed flower-like morphology, the’petals’of which were conducive to the dispersal of PANI particles and could effectively inhibit their agglomeration, so the specific surface area was improved. Three components were successfully doped together. In the ternary composite material, graphene, as a carbon-based framework, effectively loaded MoS2-PANI binary composite material. The final product demonstrated advanced supercapacitive performance including high specific capacity, rate capability and cycling stability.