A new lithium salt with dihydroxybenzene and lithium tetrafluoroborate for lithium battery electrolytes

摘要

A new unsymmetrical lithium salt containing F~, C6H4O22- [dianion of 1,2-benzenediol], lithium difluoro(l,2-benzene-diolato(2-)-o,o')borate (LDFBDB) is synthesized and characterized. Its thermal decomposition in nitrogen begins at 170 C. The cyclic voltammetry study shows that the LDFBDB solution in propylene carbonate (PC) is stable up to 3.7 V versus Li+/Li. It is soluble in common organic solvents. The ionic dissociation properties of LDFBDB are examined by conductivity measurements in PC, PC+ ethyl methyl carbonate (EMC), PC + dimethyl ether (DME), PC + ethylene carbonate (EC) + EMC solutions. The conductivity values of the 0.564 moldirr-3 LDFBDB electrolyte in PC + DME solution is 3.90 mS cm-1. All these properties of the new lithium salt including the thermal characteristics, electrochemical stabilities, solubilities, ionic dissociation properties are studied and compared with those of its derivatives, lithium difluoro(3-fluoro-l,2-benzene-diolato(2-)-o,o')borate (FLDFBDB), lithium [3-fluoro-l,2-benzenediolato(2-)-o,o' oxalato]borate (FLBDOB), and lithium bis(oxalate)borate (LBOB).