Electrolyte Designs for Lithium Ion Battery Use Under Extreme Conditions

There is increasingly a need for lithium-ion batteries (LIBs) that can operate under a wide range of conditions such as low and elevated temperatures, wide operating potential, and high-rate charging. However, battery use under such extreme operating conditions can lead to compromised cycling stability and related battery function. One of the limiting features of the battery is the electrolyte where decomposition and accelerated reactivity at the interfaces can lead to poor outcomes. Thus, new electrolytes are required to meet the needs and operating conditions of next-generation Li-ion batteries intended for use under extreme conditions. Desirable features for the electrolytes include moderate (de)solvation energy to allow for Li⁺ dissolution and transport to the electrode interfaces, chemical compatibility with the materials inside the battery, low viscosity, and wide ranges of electrochemical stability and liquid phase behavior.

Local high concentration electrolytes (LHCEs) utilize the concept of including miscible but non-Li-ion coordinating diluents to form local domains of high salt concentration dominated by contact ion pairs and cation-ion aggregates. This strategy can mitigate the low wettability and high viscosity disadvantages inherent to high concentration electrolytes (HCE) yet maintain the benefits of little free coordinating solvent. Fluorinated local high concentration electrolytes (FLHCEs) were designed to modify the chemistry and stabilize the surface electrolyte interphases of the electrodes. This talk will discuss recent results incorporating fluorinated compounds in local high concentration electrolyte (LHCE) designs showing the opportunity to tune the electrolyte properties.