LITHIUM ION SECONDARY BATTERY, BATTERY PACK, DETERIORATION DETECTION DEVICE FOR LITHIUM ION SECONDARY BATTERY, AND DETERIORATION DETECTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery in which deterioration of the battery or a degree of deterioration can be detected by a simple device in a non-destructive manner and in a mounted state, and the deterioration of the battery or the degree of deterioration can be detected without increasing a mounting area of the secondary battery and without reducing battery efficiency.SOLUTION: In a secondary battery, an outer package body is filled with a laminate in which a positive electrode and a negative electrode are laminated via a separator, and an electrolyte in which the laminate is immersed. The laminate includes the negative electrode on at least one surface of an outermost layer. The positive electrode contains a cathode active material producing a transition metal that does not relate to a charge/discharge reaction, with the charge/discharge reaction. In the outer package body at a position opposite to the negative electrode in the outermost layer, a phosphor layer is provided which is visible from the outside of the outer package body. The phosphor layer contains a phosphor that emits fluorescent light by being excited with a fluorescent X-ray emitted by converting an X-ray with which the transition metal on the negative electrode in the outermost layer is irradiated.SELECTED DRAWING: Figure 1