Electron Transport Properties

In GICs, charge transfer between graphite and intercalate produces a large concentration of charge carriers, featuring an electron or hole nature in donor or acceptor GICs, respectively, as discussed in Chapter 5. GICs are therefore metallic, in contrast with the semi-metallic properties of host graphite. The typical inplane conductivity values for GICs are in the range of ~ 105 Ω−1 cm−1, which is one order of magnitude larger than the in-plane conductivity of pristine graphite (Delhaes, 1977). It is well known that the conductivity of some GICs, such as AsF5, exceeds that of copper, suggesting the properties of synthetic metals (Vogel et al., 1977). As discussed in Chapter 5, GICs have two-dimensional (2D) features in the electronic properties inherent to their stacking structure, so that electron transport is considerably anisotropic between in-plane and interplane electron conduction processes. In the in-plane process, conduction electrons, whose concentration is estimated from eq (5.9), contribute to the coherent electron conduction, and the electrical conductivity σa or resistivity ρa is described as follows (Drude formula): . . .σa =1/ρa = Neμ= Ne2τ/(m*). . . . . .(6.1). . . where N, μ, τ, and m* are the density, mobility, relaxation time, and effective mass of the conduction carriers (electrons or holes), respectively.