Efforts were made to answer a question that has been puzzling the electrochemical community since the birth of Li-ion battery chemistry: How do ethylene carbonate (EC) and propylene carbonate (PC), with such negligible structural differences, differ so much in surface behavior on graphitic anodes that one leads to reversible Li-ion intercalation chemistry, while the other only leads to graphene structure disintegration? Through the comparative characterization of reference semicarbonate compounds and interphasial species directly collected from cycled graphitic anodes, the origin of the above distinct interphasial stabilities was tentatively attributed to the bulk physicochemical properties of the single-electron reduction products of EC and PC, rather than from the difference in interphasial reduction pathways.