Small angle neutron scattering characterization of the porous structure ofcarbons prepared using inorganic templates

Small angle neutron scattering (SANS) was used for the characterization of the microstructure of carbons derived from organic-loaded inorganic templat e materials that are used as anodes in lithium ion cells. Pillared clays (P ILC), layered silicates whose sheets have been permanently propped open by sets of thermally stable molecular props, were used as a template to load t he organic precursors. Five organic precursors, namely pyrene, styrene, pyr ene/trioxane copolymer, ethylene, and propylene, were used to load the PILC . Pyrolysis was carried out at 700 degrees C under nitrogen atmosphere. Fro m SANS, information has been derived about the pore radius, mass fractal di mension, and the cutoff length (above which the fractal property breaks dow n) on each carbon. In general, the pore radius ranges from 4 to 11 Angstrom , and the mass fractal dimension varies in the range from 2.5 to 2.9. Contr ast-match SANS studies of carbons wetted in 84% deuterated toluene indicate that a significant amount of pores in carbon from pyrene are not accessibl e to the solvent, while most of the porous network of carbon from propylene is accessible.