CAS NO:311810-76-1 Di-Fluoro Ethylene Carbonate

It is the higher reduction decomposition potential and stronger negative electrode interface adsorption property conferred by the molecular structure that enable it to undergo electrochemical reduction before the main solvent of the electrolyte; the core characteristic of its reduction decomposition potential is that it is higher than the main solvent of the carbonate class, slightly lower than the conventional film-forming additives (such as VC), and the potential range is narrow and stable, which is the key to precisely achieving "preferential film formation without premature decomposition".

DFEC achieves the coordinated regulation of multiple properties through the structural characteristics of a single molecule. It uses a dense and flexible SEI membrane rich in LiF as the core link, while optimizing interface impedance, ion conductivity and the thermal/electrochemical stability of the electrolyte. This fundamentally balances the battery's cycle life, low-temperature performance and high voltage tolerance.

The core principle of DFEC for improving the low-temperature performance of lithium batteries is to reduce interfacial impedance by using a dense LiF-containing SEI film, and to optimize the low-temperature ionic conductivity and desolvation kinetics of the electrolyte through a bifluorine structure; the conventional lowest temperature range it is applicable to is -40℃, and in extreme conditions (combined with thermal management), it can reach -50℃.

The reason why DFEC can form a film preferentially on the negative electrode is that the double-fluorine-substituted molecular structure endows it with a higher reduction decomposition potential + stronger negative electrode interface adsorption property, enabling it to undergo directional electrochemical reduction at the solid-liquid interface of the negative electrode before the main solvent of the electrolyte.

The moisture content of the energy storage battery for DFEC is ≤ 10 ppm and the acid value is ≤ 5 ppm (much stricter than those for power batteries / consumer electronics). The key lies in the working conditions of the energy storage battery, which include long cycle life (4000+ times), high-rate charging and discharging, and outdoor wide-temperature operation. The core requirement is that the electrolyte should have no side reactions and an ultra-stable interface. Even a small amount of moisture or acid can trigger a chain reaction of performance degradation, directly determining the full life cycle reliability of the energy storage cell.