NOVELTY - A non-aqueous electrolyte secondary battery comprises an electrode assembly having positive and negative electrodes (1, 2), and a porous heat resistant layer (3) between the two electrodes. The positive electrode includes a positive electrode active material layer. The negative electrode includes a negative electrode active material layer.    USE - For battery modules (claimed) used as a power source for devices requiring a high output e.g. hybrid electric vehicles and electrically-powered tools.    ADVANTAGE - The non-aqueous electrolyte secondary battery has excellent cycle life characteristic. The use of an electrode assembly can keep a sufficient amount of a non-aqueous electrolyte even when the change in the electrode assembly size is restrained.    DETAILED DESCRIPTION - A non-aqueous electrolyte secondary battery comprises an electrode assembly; a non-aqueous electrolyte, and a rectangular battery case (4) for housing the electrode assembly and the non-aqueous electrolyte. The battery case has a thickness alpha, a width beta and a height gammay satisfying a relation: alpha less than beta and beta less than or equal to gamma. The electrode assembly includes positive and negative electrodes, and a porous heat resistant layer between the two electrodes. The positive electrode includes a positive electrode active material layer. The negative electrode includes a negative electrode active material layer. A ratio of a pore volume in a predetermined area of the porous heat-resistant layer to a theoretical capacity of the battery is 0.18-1.117 ml/Ah. The predetermined area has the same area as the positive electrode active material layer. A porosity of the porous heat resistant layer is 35-85%.    An INDEPENDENT CLAIM is also included for a battery module comprising: a stack where at least two non-aqueous electrolyte secondary batteries are stacked in its thickness direction; end plates placed at both ends of he stack; and at least two bridges for binding the non-aqueous electrolyte secondary batteries by connecting one of the end plates with the other of the end plates.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-section of a non-aqueous electrolyte secondary battery.    Electrodes (1, 2)    Heat resistant layer (3)    Case (4)    Separator (5)