In operando detection of lithium diffusion behaviors at low temperature in 18650 Li-ion battery anode

Lithium diffusion process in an 18650 cell was investigated in-operando using neutron diffraction. The graphite anode delithiation rate and the amount of discharge capacity during the discharging process were correlated with the temperature and current rate. At room temperature, the lithium diffusion rate in LiC6 phase at the high rate capability (C/5) is same as at low rate capability (C/20), which means that lithium diffusion in LiC6 crystal phase is independent of the current rate in this range during the discharge process. Lowering temperature to -20 degrees C decreases both the lithium diffusion and capacity, although the latter can be partially recovered by using lower C-rate.