Non-aqueous electrolyte secondary battery for a battery pack

PROBLEM TO BE SOLVED: To enhance safety in overcharging and reliability of each unit cell by arranging a conductive intermediate which is converted into a high resistant body in overcharging between a current collector and an active material containing layer of a positive electrode used together with a negative electrode, a separator, and a nonaqueous electrolyte. SOLUTION: Specific resistance of a conductive intermediate layer arranged between a current collector made of aluminum foil or mesh and a lithium- transition metal composite oxide of a positive electrode is for example 1 >.cm or less in normal use, but is increased to 100 times or more in overcharging exceeding voltage in full charging. The conductive intermediate layer having the specified thickness is prepared by mixing a binder of 10 wt.% or more but less than 100 wt.% based on the weight of carbonaceous conductive particles such as carbon black having good thin film forming capability and suitable specific resistance and adhesion to the current collector is ensured. Connection of a PTC element to a positive electrode or a negative electrode is useful, and current is surely shut off by heat generation of the conductive intermediate layer converted into a high resistance body by overcharge.