Graphite Nanofibers as an Anode for Li Rechargeable Batteries

There is a need for the incorporation of nanophase electrode materials in Li-ion batteries in order to obtain an improvement in the performance of the device over current systems. Graphitic carbons have been the preferred materials for the anode, whichhosts the intercalation of the Li ion. While these materials have met with a significant degree of commercial success there is room for improvements in the anodic performance. Recently, novel nanocarbons such as multi-walled carbon nanotubes and graphiticnanofibers have been synthesized via the catalytic decomposition of hydrocarbons or CO with hydrogen at 600¿C. We plan to determine the suitability of catalytically grown carbon nanostructures as anodes for lithium ion batteries. These materials are knownto expose a large fraction of edge sites that are potential access points for Li ions. The effect of morphology and crystalline perfection of these types of materials as well as the merits of modifying the chemical functionality of the structures withregard to improving the efficiency of the lithium intercalation process on the performance as anodes will be assessed. Specifically we shall compare the reversible capacity and discharge potential of the nanostructured carbons for the Li species to that ofthe current electrode materials. Portable energy is an essential requirement for electronic devices such as computers, telephones, etc. The military uses rechargeable batteries to power field radios, night vision goggles, telemetry systems, chemical agentmonitors and lightweight vehicles. Li-ion batteries are currently the best energy storage devices because they produce about 3 times the energy density and voltage of NiCd batteries. The importance of this technology can be assessed in terms of economicfigures that indicate sales of 2 billion US dollars in 1997. US companies have withdrawn from this market because the high cost of production has prevented them from competing with Japan. The reduction of costs and improvements in the performance of Li-ionbatteries based on carbon nanomaterials could place the US back in the market, should new and inexpensive materials be identified.