NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte secondary battery in which the charge and discharge cycle life is improved.

SOLUTION: The a non-aqueous electrolyte secondary battery comprises a negative electrode 4 containing a graphite material and an non-aqueous electrolyte. The graphite material has a heat of immersion at 25°C in the range 0.1-1.5 J/g by an immersion media dissolving LiBF41.5 mol/L in a mixed solvent ( volume ratio (EC:GBL)=1:2 ) made of ethylene carbonate (EC) and γ-butyrolactone (GBL) and has a peak appearing in the diffraction angle 2θ of 42.8°-44.0° and 45.5°- 46.6° in the X-ray diffraction measurement using CuKα rays, and the non-aqueous electrolyte contains a non-aqueous solvent that contains EC and GBL in the volume ratio (EC:GBL) in the range 1:2-1:4 and LiBF4dissolved 1-2.5 mol/L in the above non-aqueous solvent.

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