Lithium ion battery observation method, test lithium ion battery and method for producing the same

摘要

PROBLEM TO BE SOLVED: To provide a method of observing an internal structure of a lithium ion battery having a structure substantially the same as an actual product, from a direction parallel to an extension direction of a positive electrode plate and a negative electrode plate.SOLUTION: A chargeable and dischargeable lithium ion battery (E) for test which has an observation window including a transparent plate 15 extending in a direction orthogonal to a positive electrode plate 2 and a negative electrode plate 3, and in which electrolytic solution is encapsulated, is formed by using a lithium ion battery structure 1. The lithium ion battery (E) for test is disposed on a stage of an imaging device, and set so that the transparent plate of the observation window becomes orthogonal to an optical axis of an objective lens of the imaging device. An observation area between the positive electrode plate and the negative electrode plate of the lithium ion battery is imaged from a direction parallel to an extension direction of the positive electrode plate and the negative electrode plate, via the transparent plate of the observation window. By imaging a two-dimentional color image of the observation area by using a confocal microscope, secular change in color of an active material and generation and growth of dendrite can be observed.