Establishing Structure-Property Relationships for Advanced Electrolytes

Abstract

Conventional electrolytes limit the long-term cycling stability, high voltage stability, and thermal stability of lithium-ion batteries.1 As a consequence, there is significant research in the battery field towards developing novel high-stability electrolyte solvents and additives. In order to rationally design better electrolytes, we must gain a fundamental understanding of 1) how these molecules function in the battery, including mechanisms of solvation, surface interaction, and bulk reactivity; and 2) how the structure of the molecule contributes to its properties and behavior.Silatronix, Inc. has developed a suite of tools and best practices optimized to gain this type of fundamental electrolyte understanding. We use a multi-pronged approach through post-test analysis of the electrolyte, electrodes, and gas to quantitively track solvent and additive reaction pathways and solvation behavior. Electrolyte compounds are designed and synthesized in ‘molecular families’, groups of similar molecules with one varying structural feature functional group. For example, the number of fluorines attached to a molecule may be varied. The ‘molecular family’ design scheme allows for testing the functionality of specific electrolyte structural elements in the battery as it undergoes aging through cycling and storage. In this presentation, we will detail our process for elucidating structure-property relationships as applied to various electrolyte additive structures. These principles and practices can be broadly applied in the development of novel advanced functional electrolytes. Xu, K. Rev. 2014, 114, 11503; Li, B., et al. Electrochim. Acta 2014, 147, 636; Dedryvère, R. et al., J. Phys. Chem. C. 2010, 114, 10999.