Hierarchical Graphene Macroassemblies

M.A. Worsley, M.D. Merrill, M.E. Suss, A. Wittstock, M. Stadermann, J.H. Satcher, J. Biener, T.F. Baumann
Lawrence Livermore National Laboratory, US

Keywords: graphene, energy, self assembly, battery, capacitor

Summary:

Graphene has shown the potential to significantly impact a number of different technologies, including energy storage. Properties such as high surface areas and electrical conductivity make it a promising material for hydrogen storage, battery, and ultra capacitor applications. One route to realizing the full potential of graphene in energy storage applications is the assembly of three-dimensional macroscopic graphene networks that retain the properties of individual graphene sheets. Herein we report the assembly of graphene sheets into a hierarchical architecture with length scales extending from the nanoscale to the macroscopic regime. These graphene macroassemblies are formed using sol-gel chemistry to cross-link suspensions of single layer graphene oxide (GO). The hierarchical structure possesses a number of novel properties including mechanical stiffness (50 MPa) and electrical conductivities (100 S/m) orders of magnitude higher than previously reported, surface areas that approach the theoretical values expected for a single graphene sheet (~2500 m2/g), and extraordinarily large mesopore volumes (greater than 5 cc/g). Finally, exceptional energy storage behavior was observed. The graphene-based electrode simultaneously exhibited high energy and power densities in both organic and inorganic electrolytes. The details of the synthesis and characterization of these novel graphene macroassemblies will be presented.