Live-Formation of Interphases in Li Ion Batteries

The chemical composition and morphology of interphases dictate not only the reversibility (cycle or calendar life), but also the kinetics of the cell chemistry (power density), and it has been well-recognized that the complicated interplay among electrolyte components (solvent, salt anion, additive) and electrode surfaces affect interphasial properties. While there is general agreement on the formation of the interphase on graphitic anodes from electrolyte component decomposition,  the roles of anions and additives is not well characterized and the existence and nature of an analogous interphase on cathode surfaces remains debatable. This presentation summarizes our efforts in investigating the live-formation of interphases in Li ion batteries on both cathodes and anodes under various chemical and electrochemical environments, and the identified key factors that affect the key interphasial properties.