Fast‐charging of lithium‐ion batteries: A review of electrolyte design aspects

Abstract Lithium‐ion batteries (LIBs) with fast‐charging capabilities have the potential to overcome the “range anxiety” issue and drive wider adoption of electric vehicles. The U.S. Advanced Battery Consortium has set a goal of fast charging, which requires charging 80% of the battery's state of charge within 15 min. However, the polarization effects under fast‐charging conditions can lead to electrode structure degradation, electrolyte side reactions, lithium plating, and temperature rise, which are highly linked to the thermodynamic and kinetic properties of electrolytes. The conventional nonaqueous electrolytes used in LIBs consist of carbonate and cannot support fast‐charging without compromising performance and lifespan. This review outlines the challenges of fast‐charging LIBs and the requirements of electrolytes suitable for fast‐charging. Additionally, recent developments in fast‐charging electrolytes from four key perspectives: electrolyte additives, low‐viscosity co‐solvents, high concentration or localized high‐concentration electrolytes, and advanced electrolytes are summarized. Furthermore, this review provides insights for the design of fast‐charging electrolytes based on the mechanism of charging process and offers an overview of the current state and future direction of the field.