Investigation of surface films in lithium-ion batteries

Abstract

In this work, we investigate the phenomenon of surface passivation in lithium-ion batteries. Both negative and positive electrode surface films are examined using experimental and mathematical modeling techniques. Using a simplified experimental system, we form and probe surface films on glassy carbon, a model electrochemical electrode. We observe counter-intuitive behavior when comparing the surface films formed in both neat and additive-containing electrolytes in this system. The counter-intuitive behavior is partially resolved and linked to polymerization reactions that unexpectedly elongate the surface film. In the positive electrode, mathematical modeling is used to determine that surface films do not alter the impedance response of the cell after calendar aging.