Newly Designed Electrolytes Enable Lithium Batteries With Energy Density Over 700 Wh/kg
| Jerry Huang
Editor’s Note: Newly synthesized materials provide opportunities for novel electrolytes that enable lithium-metal pouch cells to achieve energy densities greater than 700 Wh/kg at room temperature and about 400 Wh/kg at -50 °C. Lithium salt LiFSI plays a very positive role in the electrolyte designs. Thanks so much to the great research and approach by Academician Jun Chen and Qing Zhao team from Nankai University. What difference and inspirations their research may bring us? Let's take a look at it.
Abstract Electrolyte solvents for electrochemical devices have been dominated by oxygen (O)-based and nitrogen (N)-based ligands over the past decades, for which the dipole–ion (Li+, Na+ and so on) interaction usually lays the foundations of ion dissociation and transport but frustrates the charge transfer process at the electrolyte–electrode interface. Here, by synthesizing alkanes with monofluorinated structures, we show that fluorine (F)-based ligands with designed steric hindrance and Lewis basicity enable salt dissolution of more than 2 mol/L. Among them, 1,3-difluoro-propane (DFP)-based Li-ion electrolyte is endowed with all merits for energy-dense and low-temperature batteries, including low viscosity (0.95 cp), high oxidation stability (>4.9 V) and ionic conductivity of 0.29 mS/cm at −70 °C. By incorporating F atoms in the first solvation shell, the weak F–Li+ coordination facilitates the Li plating/stripping process with Coulombic efficiency (CE) up to 99.7% and exchange current density one magnitude larger than O–Li+ coordination at −50 °C. The electrolytes further enable the operation of lithium-metal pouch cells under an electrolyte amount of less than 0.5 g/Ah, achieving energy densities greater than 700 Wh/kg at room temperature and about 400 Wh/kg at −50 °C. The hydrofluorocarbon (HFC) electrolytes in this work provide a feasible approach to building electrochemical systems beyond traditional coordination chemistry.
Reference
https://doi.org/10.1038/s41586-026-10210-6