In-Situ Electrochemical Dilatometry Study for Understanding Volume Changes of the Graphite Electrodes for Lithium-Ion Battery

Abstract

In-situ electrochemical dilatometry is applied as an analytical technique to investigate the effect of both solid electrolyte interface (SEI) formation and the microstructure of the electrode on the dilation behavior of the graphite electrodes during lithium ion intercalation at the same time. It was found that the dilation and contraction behavior of the graphite electrode was dependent on the microstructure of the graphite electrode. The relationship between the microstructure, such as preferred orientation of graphite particles and the pore structure, and the volume changes of the graphite electrode were investigated by half-cell type in-situ electrochemical dilatometer during cycling. Dilation behavior of graphite electrodes monitored by in-situ dilatometer clearly showed the volume changes of the graphite electrodes induced by Li ion intercalation/de-intercalation as well as the SEI layer formation, and how the microstructure of the electrodes affects their volume expansion upon lithium ion intercalation. It was also found that differential dilation plots of the graphite electrodes upon lithiation and delithiation gave us more detailed information of dilation and contraction behaviors with respect to the amount of Li ion intercalated into graphite.