Chinese team reports hydrofluorocarbon electrolyte for 700 Wh/kg lithium battery

A research team led by Nankai University and the Shanghai Institute of Space Power-Sources has reported a new hydrofluorocarbon (HFC) electrolyte that enabled lithium-metal pouch batteries with energy density above 700 Wh/kg, while maintaining operations at temperatures as low as -70 C. The work was published in Nature on Feb. 25 in a paper titled Hydrofluorocarbon electrolytes for energy-dense and low-temperature batteries.

The study was completed by teams led by Jun Chen and Qing Zhao at Nankai University and Yong Li at the Shanghai Institute of Space Power-Sources, part of China Aerospace Science and Technology Corp.’s Eighth Academy, according to Nankai University. Nankai said doctoral student Lanqing Wu was the paper’s first author, with Zhao, Chen, and Li serving as corresponding authors.

The central advance lies in electrolyte chemistry. According to the paper, the researchers moved away from the oxygen-coordination framework that underpins conventional carbonate-based lithium battery electrolytes and designed a fluorine-coordinated system based on monofluorinated alkane solvents. Using 1,3-difluoropropane (DFP) as a core solvent, they achieved lithium salt dissolution above 2 mol/L, challenging the longstanding assumption that fluorinated hydrocarbons cannot effectively dissolve lithium salts at high concentration.

The reported performance figures are notable. The Nature paper says the DFP-based electrolyte delivered low viscosity of 0.95 cP, oxidation stability above 4.9 V, and ionic conductivity of 0.29 mS/cm at -70 C. Based on this electrolyte, the team demonstrated lithium-metal pouch cells with peak room-temperature energy density of 707 Wh/kg, or more than twice the level typically associated with today’s commercial lithium-ion batteries. Nankai also said the cell maintains energy density of about 400 Wh/kg at -50 C and continued operating at -70 C.

The work also points to a possible route past two persistent battery trade-offs: energy density and low-temperature performance. In the paper, the researchers argue that weaker lithium-fluorine coordination can reduce dissolution barriers and support faster charge transfer under cold conditions, while the solvent’s wetting behavior may also reduce electrolyte usage. The study reported lithium plating/stripping Coulombic efficiency of 99.7% at room temperature and 98.0% at -70 C.

Nankai said the technology could have applications in electric vehicles, aerospace, deep-space exploration, embodied robotics, low-altitude aircraft, and devices operating in polar or other ultra-cold environments. That breadth of possible use cases reflects the combination of high specific energy and wide-temperature operation, which remains difficult to achieve in current battery systems.

The paper appears in Nature volume 651, pages 383-389, with DOI 10.1038/s41586-026-10210-6. Beyond the headline cell performance, its importance lies in opening a new electrolyte design direction for next-generation lithium-metal batteries, especially where both weight and cold-weather operation are critical.