Battery

1. A battery comprising:

a rectangular box-shaped battery case, an inner portion of which is sealed;

a battery module housed in the battery case and being an aggregation of a plurality of battery cells;

a tubular heat resistant sheet arranged between the battery case and the battery module in a state of covering an entire side surface of an inner wall surface of the battery case;

wherein the battery case comprises:

a rectangular box-shaped lower case, an upper surface of which is opened and into which the battery module is housed; and

a rectangular box-shaped upper case, a lower surface of which is opened and joined with the lower case in a state of blocking an upper surface opening of the lower case,

wherein the heat resistant sheet is arranged in a state of covering at least a joint portion and a longitudinal side portion, the joint portion being a lateral side joint portion joining between the lower case and the upper case of the battery case, and the longitudinal side portion being a longitudinal side portion between adjacent side surfaces of the battery case, and

wherein,

the heat resistant sheet comprises four pieces of L-shaped members combined in a rectangular frame shape, in a state of providing portions partially overlapped side by side,

each of the four pieces of L-shaped members includes a piece of sheet main body bent into an L shape,

each of the four pieces of L-shaped members is adhered on the inner wall surface of the battery case by a double-sided tape, and

overlapped portions of two adjacent L-shaped members are movable.

2. The battery of claim 1 , wherein the heat resistant sheet is formed from polyimide resin or Teflon resin, and is an air infiltration preventing sheet preventing air from infiltrating into the battery case.