A non-aqueous electrolyte secondary battery including: a positive electrode having a positive electrode material mixture containing a composite lithium oxide; a negative electrode; a polyolefin separator; a non-aqueous electrolyte; and a heat-resistant insulating layer interposed between the positive and negative electrodes. The positive electrode material mixture has an estimated heat generation rate at 200° C of not greater than 50 W/kg. The positive electrode and the negative electrode are wound together with the separator and the heat-resistant insulating layer interposed therebetween.