| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrolyte for a lithium secondary battery particularly excellent in its cycle characteristics by containing fluorine including electrolyte which discharges a non-aqueous solvent and lithium ion and limiting the included quantity of fluorine-containing impurities. SOLUTION: Fluorine-containing electrolyte capable of discharging lithium ions of LIPF6 , LiBF4 , etc., is dissolved, up to its concentration of such extent about from 0.1 to 3M, in a non-aqueous solvent produced by mixing together a high dielectric solvent and low viscosity solvent with a ratio about from 1:9 to 4:1 so as to obtain an electrolyte used for lithium secondary battery. In this electrolyte, an included quantity of fluorine-containing impurities having a chemical shift value in a range from 0 to -200ppm in<19> F-NMR spectrum, is set to less than 0.02wt.% as fluorine atom, preferably within a range from -40 to -160ppm is set to less than 0.005%. This electrolyte can be obtained by subjecting respective solvent to precise distillation and mixing them together and dissolving therein, fluorine-containing electrolyte subjected to vacuum heat treatment. |
