FILLING MEMBER AND BATTERY PACK

A filling member to be interposed between pouch cells of a battery pack,the filling member having a first surface orthogonal to a thickness direction thereof and a second surface opposite to the first surface,wherein θd1 and θd2 defined below satisfy formulas (1) and (2) below, respectively, wherein θp satisfies formula (3) below, and wherein θd1 > θd2 holds: θd1≥3.0×10−3m2⋅K/W,θd2≤8.0×10−3m2⋅K/W,0.5K/W≤θp1≤1000K/W,0.5K/W≤θp2≤1000K/W,θd1: a heat transfer resistance per unit area in the thickness direction when the average temperature of one of the first and second surfaces exceeds 180°C,θd2: a heat transfer resistance per unit area in the thickness direction when the average temperatures of the first and second surfaces both do not exceed 80°C,θp1: a heat transfer resistance in a plane direction when the average temperature of one of the first and second surfaces exceeds 180°C,θp2: a heat transfer resistance in the plane direction when the average temperatures of the first and second surfaces both do not exceed 80°C.