Characterizing the effects of the alkyl chain length of linear organic carbonates on lithium ion electrolyte structure and dynamics: A solvent perspective

Abstract

© The Electrochemical Society. Lithium ion batteries have become the workhorse of the portable energy storage industry, yet there remains a strong need to improve their safety and efficiency. While many studies have focused on improving the electrodes or optimizing the electrolyte composition, few studies have focused on characterizing the electrolytes at the molecular level. In this work, we have utilized both steady-state and time-dependent infrared spectroscopies to characterize the structure and dynamics of the free carbonates both in neat solvents and within lithium-ion electrolytes. Time-resolved studies reveal similar dynamics of the bulk carbonates; however, a slowdown of the bulk carbonate dynamics occurs upon the addition of lithium salt. Thus, our studies reveal that the free carbonate molecules become significantly more ordered upon the addition of a lithium salt, which reveals further insight into the molecular-level structure of these electrolytes