Ar-Rehman

Lithium battery chemistry with fluorinated electrolyte is an important breakthrough for longer-range of EVs

Chinese scientists have announced a significant advancement in lithium battery technology. They have achieved an energy density of approximately 700 watt-hours/kg. The breakthrough was achieved by researchers from Nankai University in collaboration with the Shanghai Institute of Space Power Sources. The research team designed and synthesised a series of novel fluorinated hydrocarbon solvent molecules. The high-energy lithium battery technology could have impactful applications for longer-range EVs. Chinese scientists have developed a new type of electrolyte, marking a breakthrough in the country's core lithium battery technology. The achievement is expected to double the range of existing lithium batteries and significantly improve their low-temperature performance. The electrolyte, which serves as the critical medium connecting the positive and negative electrodes in lithium batteries, functions like a "highway" for ion conduction. It plays an indispensable role in determining energy efficiency, operational stability and temperature adaptability.

The work focuses on redesigning the battery’s electrolyte, which plays a crucial role in transporting lithium ions between electrodes and directly influences performance, stability and efficiency. Conventional lithium batteries typically rely on carbonate-based electrolytes which coordinate lithium ions through oxygen atoms. While widely used, these solvents have limitations, including restricted ion mobility and reduced effectiveness in low-temperature environments. Conventional electrolytes on the market predominantly use oxygen- and nitrogen-based ligands as solvents. Although these compounds effectively dissolve lithium salts, they impede charge transfer, creating persistent bottlenecks in enhancing energy density and low-temperature performance. Data shows that traditional lithium batteries achieve an energy density of approximately 300 watt-hours/kg at room temperature, a figure that plummets to below 150 watt-hours/kg at minus 20 degrees Celsius. To overcome these limitations, the research team has developed hydrofluorocarbon electrolytes, which significantly reduce viscosity while enhancing oxidative stability and low-temperature ionic conductivity, thereby boosting the low-temperature energy output of high-energy-density lithium batteries.

The research team new electrolyte system is based on fluorinated hydrocarbon solvents, which alters how lithium salts dissolve and interact at the molecular level. By carefully adjusting the electronic structure and spatial arrangement of the solvent molecules, the scientists reduced the strength of lithium–fluorine interactions, allowing ions to move more freely. This innovation enabled the battery to reach about 700 Wh/kg at room temperature and maintain roughly 400 Wh/kg even at extremely low temperatures around −50°C. For comparison, leading commercial battery producers such as CATL currently achieve energy densities in the range of about 250–255 Wh/kg at the pack level. "With a two- to threefold increase or more in room-temperature energy storage capacity for lithium batteries of the same mass, the range of electric vehicles can be extended from 500-600 km's to over 1,000 km's," Li said. "Remarkably, these batteries continue functioning normally even in extreme conditions as low as minus 70 degrees Celsius."

Although the new research result represents a laboratory-scale achievement rather than an immediately commercial product, it marks a substantial step toward ultra-high-energy batteries. If successfully scaled and validated for safety and cost-effectiveness, this technology could have major implications for electric vehicles, aerospace systems, robotics and other applications requiring lightweight power sources capable of operating in harsh environments. The research team designed and synthesised a series of novel fluorinated hydrocarbon solvent molecules, achieving effective dissolution of lithium salts in the electrolyte and successfully replacing the traditional lithium-oxygen coordination mode. These batteries maintain a high energy density of nearly 400 watt-hours/kg even in environments as cold as -50°C. This technological breakthrough holds great promise across multiple sectors. In high-tech applications, it could provide reliable endurance and load capacity operating in frigid environments. If such high-energy lithium battery technology can be translated from the lab to mass manufacturing, it could have impactful applications not just for longer-range electric vehicles but also for other areas which require lightweight, high-capacity power sources. However, translating experimental breakthroughs into commercially viable products usually requires further engineering work, rigorous safety validation and optimization for real-world use cases before these next-generation batteries appear in consumer products.

For everyday consumers, it promises substantial improvements in EV range and smartphone standby time under cold conditions, effectively addressing widespread concerns about battery capacity and temperature adaptability. The study shows that researchers synthesized alkanes with monofluorinated structures. The study shows that fluorine (F)-based ligands with designed steric hindrance and Lewis basicity enable salt dissolution of more than 2 mol l−1. “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−1 at −70 °C,” said researchers.