To provide a lithium ion secondary battery simultaneously achieving excellent output characteristics (in particular, low temperature output characteristics) and excellent durability even without an external unit.
The lithium ion secondary battery provided by the present invention includes a positive electrode, a negative electrode and a nonaqueous electrolyte. The positive electrode contains a lithium-containing olivine type compound as a main constituent of a positive electrode active material. The positive electrode further contains 2-20 parts by mass of active carbon relative to 100 parts by mass of the positive electrode active material. The active carbon has an average grain size in a range of from 0.1 to 1 μm and a specific surface measured by a nitrogen absorption method in a range of from 0.1 to 1,000 m2/g.
MATSUMURA YOSHIHIRO
KUME TETSUYA
CATALER CORP
Michiko Oi
Teshima Masaru
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