Electrolytes that reduce electro-osmotic drag improve fast charging of lithium-ion batteries
- Chang-Xin Zhao
- Zeyi Wang
- David Jacobson
- Yue Li
- Boris Khaykovich
- Sean Fayfar
- Lei Zheng
- Jacob LaManna
- Xilin Chen
- Daniel S. Hussey
- Fu Chen
- Gabriel M. Veith
- Chunsheng Wang
2025-11-13
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.