Nonaqueous electrolyte secondary battery

A nonaqueous electrolyte secondary battery, comprising:

• an electrode group including a positive electrode, a negative electrode containing a material for absorbing-desorbing lithium ions, and a separator arranged between the positive electrode and the negative electrode;
• a nonaqueous- electrolyte impregnated in said electrode group and including a nonaqueous solvent and a lithium salt dissolved in said nonaqueous solvent;
• and
• a jacket for housing said electrode group and having a thickness of 0.3 mm or less,
• wherein said nonaqueous solvent contains γ-butyrolactone in an amount larger than 50% by volume and not larger than 95% by volume based on the total amount of the nonaqueous solvent.

A nonaqueous electrolyte secondary battery, comprising:

• an electrode group including a positive electrode including a collector and a positive electrode layer formed on one or both surfaces of said collector and containing an active material, a negative electrode including a collector and a negative electrode layer formed on one or both surfaces of said collector and containing a material for absorbing-desorbing lithium ions, and a separator arranged between the positive electrode and the negative electrode;
• a nonaqueous electrolyte impregnated in said electrode group and including a nonaqueous solvent and a lithium-salt dissolved in said nonaqueous solvent;
• and
• a jacket for housing said electrode group, said jacket being made of a sheet having a thickness of 0.5 mm or less including a resin layer,
• wherein said positive electrode layer has a porosity lower than that of said negative electrode layer, said positive electrode layer has a thickness of 10 to 100 μm, and said nonaqueous solvent contains 40 to 95% by volume of γ-butyrolactone based on the total amount of the nonaqueous solvent.

A nonaqueous electrolyte secondary battery, comprising:

• an electrode group including a positive electrode including a collector and a positive electrode layer formed on one or both surfaces of said collector and containing an active material, a negative electrode including a collector and a negative electrode layer formed on one or both surfaces of said collector and containing a material for absorbing-desorbing lithium ions, and a separator arranged between the positive electrode and the negative electrode;
• a nonaqueous electrolyte impregnated in said electrode group and including a nonaqueous solvent and a lithium salt dissolved in said nonaqueous solvent;
• and
• a jacket for housing said electrode group and having a thickness of 0.3 mm or less;
• wherein said positive electrode layer has a porosity lower than that of said negative electrode layer, said positive electrode layer has a thickness of 10 to 100 μm, and said nonaqueous solvent contains 40 to 95% by volume of γ-butyrolactone based on the total amount of the nonaqueous solvent.