Lithium-ion Transfer Kinetics through Solid Electrolyte Interphase on Graphite Electrodes

For the development of lithium-ion batteries (LIBs) for electric vehicles, the reduction in the internal resistance of LIBs is strongly required. On the graphite negative electrodes, solid electrolyte interphase (SEI) is inevitably formed and causes partly the internal resistances. In addition, SEI covers the surface of graphite negative electrodes and affects the active sites for lithium-ion intercalation/deintercalation reactions. In this study, we investigated the influence of SEIs derived from vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethylene carbonate (EC) on the active sites for lithium-ion intercalation/deintercalation at highly oriented pyrolytic graphite (HOPG). We clarified the relation between the standard rate constant (k(0)) of [Ru(NH3)(6)](3+/2+) that is a parameter for the edge site of graphite and the interfacial lithium-ion transfer resistance (R-ct) in various electrolyte solutions that deliver different SEIs. In the plots of k(0) vs. R-ct(-1), there is a positive linear correlation between these two parameters, and the slopes increased in the order VC < EC < FEC. Additionally, the activation energy for the interfacial lithium-ion transfer remained unchanged despite the variation in SEIs. Based on these results, we conclude that SEIs affected the frequency factor of Arrhenius equation for the interfacial lithium-ion transfer on graphite. (C) The Electrochemical Society of Japan, All rights reserved.