Researchers show liquefied gas electrolyte helps develop refractory, recyclable lithium metal batteries

Gasgoo News As society transitions to an age without electricity, energy storage technology must continue to evolve to meet growing demands.To achieve an emission-free future, widely used Li-ion batteries require significant improvements in terms of high energy density, safety, temperature resilience, and environmental sustainability.

According to foreign media reports, a team of engineers led by Professor Y. Shirley Meng of the Pritzker School of Molecular Engineering at Chicago has demonstrated that a liquefied gas electrolyte can provide these four basic Meng's research in his labs at UC San Diego and the University of Chicago has paved the way for the large-scale development of leading, sustainable, fire-resistant batteries.

In 2017, a team of nanoengineers at UC San Diego discovered the HFC molecule.This molecule is a gas at room temperature and liquefies under certain pressure.The team then invented a new type of electrolyte, called a "liquefied gas electrolyte" (LGE).

The use of liquefied gas electrolytes greatly broadens the choice of electrolyte solvent molecules.The screened fluoromethane and difluoromethane small molecules have the characteristics of low melting point, fast kinetics and wide voltage window.On this basis combined with cosolvents, these liquefied gas electrolytes exhibit excellent low-temperature performance (below -60 °C), Li metal Coulombic efficiency (>99.8%), and high-performance high-voltage cathodes.However, LGE electrolytes still have some disadvantages.There are safety and environmental risks to the system because the molecules used have high saturation vapor pressures and are as flammable as most electrolytes.

The researcherswanted to replace the highly soluble liquid cosolvent with dimethyl ether (Me2O), the smallest ether molecule."As a gas molecule, Me2O can only be used in liquefied gas," said Yin, a UC San Diego nanoengineering doctoral student. "It can only work under a pressurized system and can provide better lithium-metal interface and stability while maintaining fast dynamics. .

Yang, a nanoengineering doctoral student at UC San Diego, hopes to further refine the system."Continuing to use current weak solvents for FM and DFM cannot change the high pressure and flammability defects. Instead,researchersshould focus on finding bonds with increased fluorinated carbons."

The researcherslooked at the structure of fluoromethane to find fluorinated molecules with longer carbon chains, while maintaining the inherent advantages of liquefied gas, such as low melting point, low viscosity and maintaining a certain polarity.Considering all the above requirements, 1,1,1,2 tetrafluoroethane (TFE) and pentafluoroethane (PFE) were proposed.Even more surprising, these two molecules are the main components of some fire extinguishers.Not only non-flammable, but also has excellent fire extinguishing performance.