Investigation of Lighiated Carbons by Transmission Electron Microscopy adn X-ray Diffraction Analysis

摘要

The microstructures of lithiated synthetic graphite and carbon black were studied by high-resolution transmission electron microscopy and X-ray diffraction analysis. Information about the crystal structure of carbon containing various Li ocmpositions can provide useful insights to our understanding of the Li storage mechanism in carbonaceous materials. Samples with ocmpositions of LI_0.93C_6or Li_0.45C_6 were found to contain both stage-one and stage-two compounds. These observations are consistent with XRD data. The changes in sample microsturcture as the results of lithiatin and exposure to electron irradiation were obsrved by TEM and recorded over several minutes in the microscope environment. Selected area electron diffraction patterns indicated that the lithiated samples quickly changed composition to LiC_24, which appeared to dominate during the brief analysis period. The layer planes in the lattice image of a disordered carbon black after Li insertion are poorly defined, and changes in the microstrucute of these lithiated carbons was not readily apparent. Observations on these lithim intercalation compounds as well as the limitation of the experimental procedure will be pesented.