A team of Chinese researchers developed a new electrolyte based on monofluorinated hydrofluorocarbons (HFC) that transforms the performance of lithium batteries.
According to the study published in Nature at the end of 2025, this chemistry allows achieving energy densities greater than 700 Wh/kg at room temperature and around 400 Wh/kg at −50 °C.
This breakthrough represents a leap compared to current high-performance cells, which usually range between 250–270 Wh/kg under normal conditions.
Strategic Context
In a world moving towards accelerated electrification —electric mobility, renewable storage, electrified industry— the ability to maintain performance in extreme cold is no longer a technical detail but becomes a strategic condition. Not all applications operate at 20 °C, and many regions face polar or continental climates.
The Role of the Electrolyte
The electrolyte transports lithium ions between the anode and cathode. Traditional solvents, based on oxygen or nitrogen, have limitations:
- Too strong coordination with the Li⁺ ion.
- High viscosity when modified.
- Loss of efficiency in fast charging and low temperatures.
The problem is concentrated at the electrode–electrolyte interface, where kinetics slow down in the cold.
Innovation with HFC
HFCs had been considered before, but with low salt solubility and stability issues. The key to the new development was enhancing the Lewis basicity of the fluorine atoms, achieving a weaker but stable coordination with the Li⁺ ion.
Six solvents were synthesized and evaluated in coin and pouch cells. The new compounds managed to dissolve lithium salts at concentrations exceeding 2 mol/L, surpassing a historical barrier.
The Star Electrolyte: 1,3-difluoropropane (DFP)
- Low viscosity: 0.95 cP.
- Stability against oxidation: >4.9 V.
- Ionic conductivity: 0.29 mS/cm at −70 °C.
- Coulombic efficiency: 99.7% even under demanding conditions.
- Operation with less than 0.5 g of electrolyte per Ah, increasing overall energy density.
Potential Applications
The result is more energy per kilogram and stable operation at −50 °C. This opens new possibilities for:
- Electric vehicles in cold regions, reducing dependence on fossil fuels.
- Electric aviation and high-altitude drones, with greater autonomy.
- Renewable storage in extreme climates, where conventional batteries fail.
- Lighter mobile applications, by reducing weight and volume per unit of energy.
Future Perspectives
If stability and thermal range continue to improve —by modulating the carbon and fluorine ratio in HFCs— a new generation of high-density metallic lithium batteries could be consolidated.
The energy transition does not depend on a single technology, but advances like this are what allow everything to work better. The optimization of F–Li⁺ coordination opens a path to surpass the current ceiling of power and energy density, providing more efficiency and climate resilience.
