Solvent-Assisted Hopping Mechanism Enables Ultrafast of Lithium-Ion Batteries LETTER

Fast charging is regarded as one of the most coveted technologies for commercial Li-ion batteries (LIBs), but the lack of suitable electrolytes with sufficient ionic conductivity and effective passivation properties hinders its development. Herein, we designed a mixed-solvent electrolyte (1 M LiPF6 in fluoroethylene carbonate/acetonitrile, FEC/AN, 7/3 by vol.) to overcome these two limitations by achieving an FEC-dominated solvation structure and an AN-rich environment. The specific AN-assisted Li+ hopping transport behavior shortens the Li+ diffusion time, doubling the ionic conductivity to 12 mS cm-1, thus endowing the graphite anode with >300 mAh g-1 at 20C and reversible (de)intercalation over a wide temperature range (from -20 to +60 degrees C). Furthermore, the designed electrolyte triples the capacity of the 1 Ah graphite||LiNi0.8Mn0.1Co0.1O2 (NMC811) pouch cells at 8C in comparison with the commercial electrolyte. The solvent assisted hopping mechanism maximizes the fast-charging capability of the electrolytes, which motivates further research toward viable next-generation highenergy LIBs.