Morphology control and thermal stability of binderless-graphene aerogels from graphite for energy storage applications

Of all the challenges facing human beings in the near future, energy related issues are likely to be the grandest. To achieve a more sustainable society with adequate renewable energy and less environmental pollution, more versatile, robust and efficient approaches in electric energy storage and conversion are needed. To achieve these goals, the development of new electrode materials with high electrical conductivity, corrosion-resistance, high specific surface area, high porosity and low cost is highly desirable. Graphene aerogels (GAs) have been focused recently due to novel properties of graphene (extremely low electrical and thermal resistivity, large carrier mobility, high surface area and mechanical elasticity) and the low cost and easy preparation of graphene from graphite. The performance of GA-based electrodes strongly depends on the morphology and structure of the GAs. However, there has been little study on the optimization of the GA nanostructures in terms of surface area, pore size, pore volume and density for energy storage devices. In this work, the GA nanostructures synthesized from commercial graphite were controlled successfully. The graphene oxide (GO) was prepared from commercial graphite powder using a modified Hummers method. A hydrothermal method was used to synthesize GAs due to its simplicity, environmental friendliness and low cost. No binders were used to prevent their negative effects to the electrical conductivity of the aerogels. Effects of fabrication conditions and the GO concentration on the GA nanostructures were also quantified. A maximum Brunauer–Emmett–Teller (BET) surface area of 394 m2/g and the lightest density of 0.042 g/cm3 were achieved when the GA with 3 mg GO/mL was hydrothermally treated at 180 °C for 1.5 h. The thermal durability analysis showed that the GAs could be stable up to 500 °C in air, with 24 h of hydrothermal treatment time. Preliminarily the GA hydrothermally treated for 6 h had an electrical conductivity of 0.004 S/cm. The experimental results of the study are useful for optimizing GA structures for energy storage applications.

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► Graphene aerogel (GA) nanostructures synthesized from commercial graphite were controlled successfully.
► A hydrothermal method was used to synthesize GAs. No binders were used.
► Effects of fabrication conditions and graphene oxide concentration on the GA nanostructures were quantified.
► A maximum BET surface area of 394 m2/g and the lightest density of 0.042 g/cm3 were achieved.
► The GAs could be stable up to 500 °C in air.