A Li-7 NMR study of a hard carbon as a function of temperature and lithiation state

Negative electrodes of lithium-ion batteries containing a hard carbon with different levels of lithiation were characterized by Li-7 NMR experiments. A dramatic effect of washing the lithiated electrodes with the solvent was observed. The spectra of unwashed electrodes in different states of lithiat ion show that three species seem to be present: covalently bonded, intercal ated and pseudo-metallic lithium species, respectively.