Patent ID: 7455932

Claim:
In a nonaqueous electrolyte secondary battery using a material capable of storing and releasing lithium as a negative electrode material and a lithium transition metal complex oxide containing Ni and Mn as the transition metal and having a layered structure as a positive electrode material, said secondary battery being characterized in that said lithium transition metal complex oxide has a BET specific surface area of less than 3 m 2 /g and gives a pH value within the range of 10.61-11.0 when it is immersed in purified water in the amount of 5 g per 50 ml of the purified water, and that an outer casing of said battery is composed at least partly of an aluminum alloy or aluminum laminate film having a thickness of up to 0.5 mm and susceptible to deformation in case of internal pressure buildup due to gas generation within the battery during storage.