Crystal structure and physical properties of lithium difluoro(oxalato)borate (LiDFOB or LiBF_2Ox)

摘要

The structural characterization and properties of lithium difluoro(oxalato)borate (LiDFOB) are reported. LiDFOB was synthesized as previously described in the literature via direct reaction of boron trifluo-ride diethyl etherate with lithium oxalate. The crystal structure of the salt was determined from single crystal X-ray diffraction yielding a highly symmetric orthorhombic structure (Cmcm, a = 6.2623(8) A, b= 11.4366(14) A,c = 6.3002(7) A. V=451.22(9) A~3, Z = 4at 110 K). Single crystal X-ray diffraction of a dihy-drate of LiDFOB yielded a monoclinic structure (P2,/c, a = 9.5580(3)A, b = 12.7162(4) A, c = 5.4387(2)A, V= 634.63(4) A~3,Z=4 at 110 K). Along with the crystal structures, additional structural information and the properties of LiDFOB (via 11~B and 19~F NMR, DSC, TGA and Raman spectroscopy) have been compared with those of LiBF_4 and LiBOB to better understand the differences between these lithium battery electrolyte salts.