(Invited) Enabling Fast Charging Lithium-Ion Batteries through Balancing Ion Transport and Solvation

Abstract

The advent of novel electrolyte chemistries has shown significant improvements in fast-charging and extreme operation capabilities. As ionic transport in the electrolyte is a dominant contributor to the rate capability of lithium-ion batteries (LIBs), addition of low-viscosity co-solvent is the most common approach to improve the transport properties of carbonate electrolytes, leading to improved rate performance and widened operation temperature window. Recent work further moves to replace carbonates entirely with low-viscosity solvents. However, such solvents reduce the long-term stability of the cells, which must be addressed before practical use. While the development of localized high concentration electrolytes (LHCEs) has shown significantly improved high voltage and wide-T stability as well as Li metal cycling stability, the substantially decreased ionic conductivity compared with SOA electrolytes makes them challenging to support <15mins charging. Here, we discuss a class of partially fluorinated, ester-based electrolytes with balanced ion transport and critical solvation properties for practical LIBs that can operate at extreme conditions including fast charging, wide temperature (T) range and high voltage.