CORRELATION BETWEEN X-RAY ABSORPTION AND CHEMICAL-POTENTIAL MEASUREMENTS IN LITHIUM INTERCALATED CARBONS

Using synchrotron radiation we measured the x-ray absorption (XAS) near the Ci, edge for powdered graphite, boron substituted graphite, and a disordered graphitic carbon. The chemical potential of Li intercalated into the same carbons has also been measured as a function of x in Li(x)C6. When Li is intercalated, the 2s electron is transferred to the C host, filling the same levels as probed by XAS. In XAS, final-state energies contain a contribution from the electron-core-hole interaction which mimics the situation in Li intercalation where Li+ interacts with conduction electrons. We show that XAS results correlate well with chemical potential measurements of intercalated Li made on the same materials.