DEFORMATION DETECTION SENSOR FOR SEALED SECONDARY BATTERY, SEALED SECONDARY BATTERY, AND DEFORMATION DETECTION METHOD FOR SEALED SECONDARY BATTERY

The present invention provides a deformation detection sensor for a sealed secondary battery, that makes it possible to detect deformation resulting from swelling of a cell (2) with a high degree of sensitivity, that does not restrict capacity, and that has excellent stability. The deformation detection sensor for a sealed secondary battery includes a polymer matrix layer (3) and a detection unit (4). The polymer matrix layer (3) contains a magnetic filler that is dispersed therein and that is adapted to change an external field in accordance with a deformation of the polymer matrix layer (3). The detection unit (4) detects change in the external field. The polymer matrix layer (3) is sandwiched in a gap between adjacent cells (2) and mounted in a compressed state.