Differentiating Contributions to “Ion Transfer” Barrier from Interphasial Resistance and Li+ Desolvation at Electrolyte/Graphite Interface

Efforts were made to differentiate the contributions to the so-called "ion transfer" barrier at the electrolyte/graphite junction from two distinct processes: (1) desolvation of Li+ before it enters graphene interlayer and (2) the subsequent migration of bare Li+ through the ad hoc interphase. By leveraging a scenario where no substantial interphase was formed on Li+ intercalation hosts, we were able to quantify the distribution of "ion transfer" activation energy between these two interfacial processes and hence identify the desolvation process of Li+ as the major energy-consuming step. The result confirmed the earlier belief that the rate-determining step in the charging of a graphitic anode in Li+ intercalation chemistry relates to the stripping of solvation sheath of Li+, which is closely interwoven with the interphasial resistance to Li+ migration.