Relaxation Analysis of Graphite Anode Materials after Charge-Discharge Cycles

Abstract

Relaxation analysis has been carried out on fresh and charge-discharge cycled graphites to evaluate the effect of cycle process on the relaxation behavior after lithium insertion. While the formed stage I at charging partly transforms into stage II during relaxation, the cycled samples exhibit smaller fraction of transformation. The charge-discharge cycles also restrict the relaxation variation in c-axis of stage II, even though lithium occupation ordering similarly occurs between the fresh and cycled samples. Variation in c-length of stage II would be the results of stage transformation from I into II, and charge-discharge process enables to follow the equilibrium stages rapidly at charging.