Non-aqueous electrolyte secondary battery

A non-aqueous electrolyte secondary battery comprising:

• (a) a positive electrode comprising a positive electrode material mixture containing a composite lithium oxide and a positive electrode current collector carrying said positive electrode material mixture;
• (b) a negative electrode comprising a material capable of absorbing and desorbing lithium;
• (c) a separator comprising a polyolefin resin;
• (d) a non-aqueous electrolyte;
• and
• (e) a heat-resistant insulating layer interposed between said positive electrode and said negative electrode,
• wherein said positive electrode active material mixture has an estimated heat generation rate at 200° C. of not greater than 50 W/kg, and
• wherein said estimated heat generation rate is determined by the steps of:
• (i) determining a relation between absolute temperature T and heat generation rate V of said positive electrode material mixture using an accelerating rate calorimeter (ARC);
• (ii) plotting a relation between the inverse of absolute temperature T as an X coordinate and the logarithm of heat generation rate V as a Y coordinate according to the Arrhenius law;
• (iii) obtaining an approximate straight line fitted to the plotted points in a heat generation temperature range of T<200° C. (473 K);
• and
• (iv) extrapolating the obtained approximate straight line to the temperature axis at T=200° C. (473 K).