In situ 7Li NMR during lithium electrochemical insertion into graphite and a carbon/carbon composite

We present a continuous static 7Li Nuclear Magnetic Resonance (NMR) experiment on a lithium/carbon battery while it is being charged and discharged. Two kinds of batteries are tested: one with a graphite electrode, the other with a carbon/carbon composite electrode. With graphite, all the intercalation stages give a NMR signature, even the early stages, difficult to isolate usually. The random, initial stage 1′ seems to occur all over the intercalation process. The response of the carbon/carbon composite electrode is quite different: it confirms the lack of a regular graphene structure and shows a slower diffusion for most of the lithium. The carbon black added for conductivity improvement does not appear to store lithium.