On the Way to New Lipophilic Delokalized Onium-fluorides- Trimethyldifluorosilicates and Perfluoroalkoholates: Synthesis, Properties and Application

In this study a range of new sources of fluoride ions with lipophilic and delocalized cations having symmetrical and nonsymetrical C-N-P , C-N-S and C-N-C backbones completely substituted by dialkylamino groups were designed to improve the 'Halex' fluorination process.Reactions of bis(dialkylamino)difluoromethane with N-trimethylsilyltetramethylguanidine and tris(diethylamino)phosphazene led to (Alk2N)2CNC(NMe2)2 Me3SiF2- and (Alk2N)2CNP(NEt2)2 HF2-, respectively. Sulfur tetrachloride reacted with tetramethylguanidine to give tris(tetramethylguanido) chloride. Depending on the reaction conditions sulfur tetrafluoride and (diethylamino)sulphur trifluoride and tetramethylguanidine or N-trimethylsilyltetramethylguanidine afforded the salts with C-N-S backbone with F-, HF2-, Me3SiF2- or Me2SiF3- counter ions. The X-Ray structures of some new salts are discussed.Convenient and scalable methods of perfluoralkoholate [OCF2RF]- preparation via reaction of mono- and bisperfluoroalkylacid fluorides as well as fluorosulfonic acids with CNC-silicates, DFI, (Me2N)2CF2 and TMAF were developed

Auf dem Wege zu neuen lipophilen, delokalisierten Onium-Fluoriden, -Trimethyldifluorsilikaten und -Perfluoralkoholaten:Synthesen, Eigenschaften, Anwendungen

In this study a range of new sources of fluoride ions with lipophilic and delocalized cations having symmetrical and nonsymetrical C-N-P , C-N-S and C-N-C backbones completely substituted by dialkylamino groups were designed to improve the 'Halex' fluorination process.Reactions of bis(dialkylamino)difluoromethane with N-trimethylsilyltetramethylguanidine and tris(diethylamino)phosphazene led to (Alk2N)2CNC(NMe2)2 Me3SiF2- and (Alk2N)2CNP(NEt2)2 HF2-, respectively. Sulfur tetrachloride reacted with tetramethylguanidine to give tris(tetramethylguanido) chloride. Depending on the reaction conditions sulfur tetrafluoride and (diethylamino)sulphur trifluoride and tetramethylguanidine or N-trimethylsilyltetramethylguanidine afforded the salts with C-N-S backbone with F-, HF2-, Me3SiF2- or Me2SiF3- counter ions. The X-Ray structures of some new salts are discussed.Convenient and scalable methods of perfluoralkoholate [OCF2RF]- preparation via reaction of mono- and bisperfluoroalkylacid fluorides as well as fluorosulfonic acids with CNC-silicates, DFI, (Me2N)2CF2 and TMAF were developed

Influence of the Fluorination Degree of Organophosphates on Flammability and Electrochemical Performance in Lithium Ion Batteries

Four symmetric compounds deriving from the alkyl chain containing tripropyl phosphate were designed and synthesized by varying substitution of fluorine in the side chains and added as co-solvents to yield 10%, 20% and 30% concentrated electrolyte formulations. The formulated electrolytes were physicochemically and electrochemically characterized and compared to a state-of-the-art organic carbonate-based electrolyte in regard to the flammability as well as any occurring trade-off in cycling performance. The addition of phosphates resulted in superior flammability behavior of the electrolyte as the flammability could be severely reduced with increased concentration of the phosphates. As the addition of such phosphate compounds to the electrolyte usually comes with a trade-off in cycling performance, electrochemical behavior was thoroughly investigated regarding ionic conductivity, anodic stability limit and cycling stability in lithium metal and lithium ion cells. The influence of the varying fluorine content as well as position of the substituted fluorine was determined and discussed. The tripropyl phosphate derivatives showed very promising cycling results hand in hand with a significant improvement achieved regarding the flammability of the electrolyte

Influence of the Fluorination Degree of Organophosphates on Flammability and Electrochemical Performance in Lithium Ion Batteries: Studies on Fluorinated Compounds Deriving from Triethyl Phosphate

Three symmetric substances originating from triethyl phosphate were specifically synthesized with varying degree of fluorination at the side chain. Different concentrations of each phosphate were evaluated as co-solvent with regard to their flammability and the electrochemical cycling performance. With higher degree of fluorination and a higher amount of the phosphate in the electrolyte, the self-extinguishing time (SET), a value to determine and compare the flammability of electrolytes, could be significantly lowered to yield a non-flammable electrolyte mixture. A specifically designed SET device is introduced, which offers more accurate results due to lowered standard deviations by minimizing random and systematic errors. As the application of phosphates as co-solvents results in a trade-off in cycling performance, a thorough determination in regard to the ionic conductivity, the anodic oxidation stability and the compatibility with anode and cathode material was carried out in half- and full-cells. The manuscript strives to establish a deeper understanding of the influence that the utilization of phosphates as co-solvents entail with special focus on the fluorination degree. It could be shown that the partially fluorinated phosphate offers the best cycling results and therefore the lowest trade-off in performance, while a severe improvement in SET could be achieved compared to the reference electrolyte