Buckypaper for energy storage and conversion

The discovery of nanomaterials has paved the way for developing novel electrochemical energy storage and conversion devices. Recent exciting developments in carbon nanotubes, nanofibers and buckypapers have clearly demonstrated the potential of nanomaterials for substantially advancing the performance of energy storage and conversion applications. A sheet of buckypaper consists of carbon nanotubes and/or carbon nanofibers, which hold themselves together via van der Waals forces and interdigitation due to their large aspect ratio. The most distinct advantages of buckypaper for energy storage and conversion include tailorable porosity, extraordinarily large surface area and high conductivity. The microstructure and porosity of buckypaper are controllable by assembling nanotubes of different diameters and aspect ratios in a novel synthesis process. Buckypaper is less corrosive and more thermally stable due to less molecular defects than carbon blacks. Free-standing buckypapers can easily be surface coated to reduce catalyst usage with controlled catalyst particle size for optimal electrochemical performance. These features make buckypaper a perfect fit for electrochemical applications. Buckypaper-supported Pt electrocatalysts have been successfully prepared by the electro-and vacuum-deposition. These electrocatalysts proved efficient when used in the cathode of a PEM fuel cell. An 88% Pt usage rating was obtained from a buckypaper-supported catalyst. The platinum utilization in the PEMFC was as high as 0.5 g_Pt/kW at 0.65 V, which is much higher than what is achievable with current commercial Pt/C catalysts. In addition to fuel cells, we are deploying buckypaper in Li-air batteries as the air electrode for optimal energy density and improved power density.