Method for producing non-aqueous electrolyte solution, non-aqueous electrolyte solution, and non-aqueous electrolyte secondary battery

Abstract

A non-aqueous electrolyte secondary battery which uses a non-aqueous electrolyte solution in which a main component of a non-aqueous solvent is a fluorinated solvent, and by which it is possible to suitably prevent a decrease in battery capacity. A method for producing the non-aqueous electrolyte solution disclosed here includes a fluorinated solvent provision step for preparing the fluorinated solvent, a highly polar solvent provision step for preparing a highly polar solvent having a relative dielectric constant of 40 or more, a LiBOB dissolution step for preparing a highly concentrated LiBOB solution by dissolving LiBOB in the highly polar solvent at a concentration that exceeds the saturation concentration in the fluorinated solvent, and a mixing step for mixing the fluorinated solvent with the highly concentrated LiBOB solution.

What is claimed is: 
     
         1 . A non-aqueous electrolyte secondary battery in which an electrode body having a positive electrode and a negative electrode is housed in a case and a non-aqueous electrolyte solution is filled between the positive electrode and the negative electrode, wherein the non-aqueous electrolyte solution is a non-aqueous electrolyte solution in which a lithium salt and LiBOB are dissolved in a non-aqueous solvent that contains a fluorinated solvent as a main component, and a SEI film derived from the LiBOB is formed on a surface of the negative electrode; and
 the volume of the fluorinated solvent is 80 to 95 vol % when the total volume of the non-aqueous solvent is taken as 100 vol %, and the amount of components in the SEI film that are derived from the LiBOB is 0.1 to 0.4 mg/cm 2 .