Partition member, assembled battery and method for controlling heat transfer in an assembled battery

Abstract

A partition member has two surfaces in a thickness direction, and separates single cells that make up an assembled battery. When the average temperature of one of the two surfaces exceeds 180° C., a thermal resistance per unit area (θ 1 ) in the thickness direction satisfies Expression 1 below, and when the average temperatures of both of the two surfaces do not exceed 80° C., a thermal resistance per unit area (θ 2 ) in the thickness direction satisfies Expression 2 below. θ 1 ≥5.0×10 −3 (m 2 ·K/W )  (Expression 1), and θ 2 ≤4.0×10 −3 (m 2 ·K/W )  (Expression 2).

What is claimed is: 
     
         1 . A partition member which has two surfaces in a thickness direction, and which separates single cells that make up an assembled battery,
 wherein when the average temperature of one of the two surfaces exceeds 180° C., a thermal resistance per unit area (θ 1 ) in the thickness direction satisfies Expression 1 below; and   when the average temperatures of both of the two surfaces do not exceed 80° C., a thermal resistance per unit area (θ 2 ) in the thickness direction satisfies Expression 2 below,
   θ 1 ≥5.0×10 −3  ( m   2   ·K/W )  (Expression 1),
 
   and 
   θ 2 ≤4.0×10 −3  ( m   2   ·K/W )  (Expression 2).
 
   
     
     
         2 . The partition member according to  claim 1 , wherein when the average temperature of one of the two surfaces is 180° C. or higher, thermal conductivity in the thickness direction is 2.0×10 −2  W/m·K or more and 2.0 W/m·K or less; and
 when the average temperatures of both of the two surfaces are 80° C. or lower, thermal conductivity in the thickness direction is 5.0×10 −2  W/m·K or more and 50 W/m·K or less. 
 
     
     
         3 . The partition member according to  claim 1 , wherein when the thickness of the single cells is denoted by L (mm), the thickness in the thickness direction is L/50 mm or more and L/10 mm or less. 
     
     
         4 . The partition member according to 1, wherein when the average temperature of one of the two surfaces exceeds 180° C. and is 300° C., the thermal resistance per unit area (θ 1 ) in the thickness direction satisfies Expression 1 below; and
 when the average temperatures of both of the two surfaces do not exceed 80° C., the thermal resistance per unit area (θ 2 ) in the thickness direction satisfies Expression 2 below. 
 
     
     
         5 . An assembled battery, comprising the partition member according to  claim 1 . 
     
     
         6 . An assembled battery, comprising:
 a plurality of single cells including a first single cell, a second single cell and a third single cell; and   a first partition member that separates the first single cell from the second single cell, and a second partition member that separates the second single cell from the third single cell,   wherein when the second single cell deviates from a normal state due to heat from the first single cell having reached an abnormal heating state, the quantity of heat transmitted from the first single cell to the second single cell via the first partition member is reduced by the first partition member and the quantity of heat transmitted from the first single cell to the third single cell maintaining the normal state is not reduced by the second partition member.   
     
     
         7 . The assembled battery according to  claim 6 , wherein the quantity of heat transmitted from the first single cell to the second single cell is reduced through an increase in the thermal resistance per unit area of the first partition member. 
     
     
         8 . The assembled battery according to  claim 6 , wherein even if the second single cell deviates from normal state, the thermal resistance per unit area of the second partition member does not increase and the quantity of heat transmitted from the first single cell to the third single cell is not reduced. 
     
     
         9 . A method for controlling heat transfer in an assembled battery in which single cells are separated by a partition member,
 wherein the partition member has two surfaces in a thickness direction, one of the surfaces being a first surface opposing a first single cell and the other surface being a second surface opposing a second single cell;   when an average temperature of the first surface does not exceed 80° C., a thermal resistance per unit area (θ 2 ) in the thickness direction satisfies Expression 2 below, whereby heat from the first single cell is transmitted to the second single cell via the partition member; and   when the first single cell reaches an abnormal heating state, the second single cell deviates from a normal state due to heat transmitted from the first single cell via the partition member, and the average temperature of the first surface exceeds 180° C. due to heat from the first single cell, then a thermal resistance per unit area (θ 1 ) in the thickness direction satisfies Expression 1 below, whereby a quantity of heat transmitted from the first single cell via the partition member is reduced,
   θ 1 ≥5.0×10 −3  ( m   2   ·K/W )  (Expression 1),
 
   and 
   θ 2 ≤4.0×10 −3  ( m   2   ·K/W )  (Expression 2).