Electrolytes that reduce electro-osmotic drag improve fast charging of lithium-ion batteries

CX Zhao and ZY Wang and D Jacobson and Y Li and B Khaykovich and S Fayfar and L Zheng and J Lamanna and XL Chen and DS Hussey and F Chen and GM Veith and CS Wang, SCIENCE, 390, 745-750 (2025).

DOI: 10.1126/science.adv1739

Fast charging (at rates greater than 4 C) is essential for high-energy lithium-ion batteries in electric vehicles yet remains challenging owing to a lack of understanding of fast-charging barriers. Conventional optimization strategies concentrate on shortening lithium-ion transport pathways through electrode structure modification, which often compromises energy densities. In this work, we demonstrate that thick- electrode fast charging is constrained by solvent withdrawal within porous electrodes and the resulting electro-osmotic drag polarization, which is driven by cation-induced electro-osmotic drag. To reduce electro-osmotic drag polarization, we designed electrolytes with weak cation solvation and strong anion solvation, where a difluorinated solvent weakens lithium-cation solvation and its difluoromethyl hydrogen atoms enhance anion solvation through hydrogen bonding. This electrolyte enables thick-electrode, energy-dense batteries to achieve 80% charge within 13 minutes.

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