Ester-Guided Dynamic Li Solvation Enables Plating-Less, Fast-Charging Li-Ion Batteries.

The extremely fast charging (XFC) of Li-ion cells is an urgent milestone in promoting the widespread adoption of electric vehicles. However, EV-targeted cell designs with thicker electrodes compromise the XFC capability when conventional electrolytes are used, leading to hazardous Li plating and a considerable loss in Li inventory. This study presents noncarbonate solvents for superionic conductive, low-viscosity high-concentration electrolytes (HCEs). A methyl acetate (MA)-based HCE with a solid-electrolyte interphase (SEI)-stabilizing additive (3MF) was comparatively examined using a dimethyl carbonate (DMC) solvent, which has an extra oxygen atom in the molecule, across all aspects, including solvation structures, interfacial kinetics, and bulk Li transport. The 3MF electrolyte demonstrated outstanding XFC performance in a pouch cell (1.2 Ah) format and outperformed DMC-based HCE, showcasing improved cycling performance at low temperatures (-20 °C), 10 C-rate (6-min charging), and with a thick electrode (6.0 mAh cm). By satisfying the energy barrier thresholds for Li desolvation and Li migration across the SEI, MA can guide smaller solvation clusters and serve as a molecular lubricant along the Li percolation pathway in the HCE framework, which is crucial for boosting XFC capabilities.