Thermally oxidized graphites as anodes for lithium-ion cells

Lithium intercalation and deintercalation processes occur through solid ele ctrolyte interfaces (SEIs) on the zigzag and armchair faces of graphite. Su ch SEIs are formed by reaction of surface groups on the graphite with lithi um upon charging. The nature of this interface to a large extent determines the reversible and irreversible capacities of the graphite. We have invest igated the influence of mild oxidation of samples of natural graphite and c arbon nanotubes on the surface characteristics of the films formed on these materials upon lithium intercalation. The surface groups formed upon oxida tion have been characterized using Fourier transform infrared (FT-IR) spect roscopy. The reversible and irreversible capacities of the thermally oxidiz ed samples are discussed in terms of the surface film composition as well a s enhanced surface area that contributes to increased number of sites for l ithium intercalation. (C) 2001 Published by Elsevier Science B.V.