Li-ion diffusion in Li intercalated graphite C6Li and C12Li probed by μ+SR

In order to study a diffusive behavior of Li + in Li intercalated graphites, we have measured muon spin relaxation (μ + SR) spectra for C 6 Li and C 12 Li synthesized with an electrochemical reaction between Li and graphite in a Li-ion battery. For both compounds, it was found that Li + ions start to diffuse above 230 K and the diffusive behavior obeys a thermal activation process. The activation energy ( E a ) for C 6 Li is obtained as 270(5) meV, while E a = 170(20) meV for C 12 Li. Assuming a jump diffusion of Li + in the Li layer of C 6 Li and C 12 Li, a self-diffusion coefficient D Li at 310 K was estimated as 7.6(3) × 10 −11 (cm 2 s −1 ) in C 6 Li and 14.6(4) × 10 −11 (cm 2 s −1 ) in C 12 Li. We have demonstrated that a local magnetic probe, μ + SR, provides a self diffusion coefficient of Li in Li intercalated graphites.