Intercalation mechanism of lithium ions into graphite layers studied by nuclear magnetic resonance and impedance experiments

The intercalation mechanism of lithium ions into graphite layers has been s tudied in organic solvents employing nuclear magnetic resonance (NMR) and e lectrochemical impedance spectroscopy (EIS) experiments. The lithium ions s olvated with these solvent molecules were shown to intercalate into the gra phite lattices by NMR experiments, which is also supported by the EIS resul ts. Association constants of the complexes formed between lithium ions and solvent molecules have been determined by Li-7 NMR spectroscopic experiment s. The Li-7 and C-13 solid-state NMR and EIS results obtained from fully ch arged graphite electrodes clearly indicate that solvent or crown ether mole cules are cointercalated into the graphite layers with the lithium ions. We conclude from these results that solvent and/or crown ether molecules are dragged into the graphite layers by lithium ions when they are intercalated . (C) 2001 The Electrochemical Society. Ail rights reserved.