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

摘要

Provided is an observation method for a lithium ion battery, which enables accurate microscopic observation even when an observation cross section is formed by a mechanical cutting process. An observation window including a cell body (30) for holding a holding tool (42) for holding a test lithium ion battery having a positive electrode plate, a negative electrode plate, and a separator, and a transparent plate (36) is formed. An observation cell having a flange (31) that is sealingly engaged with the cell body is prepared. Subsequently, the test lithium ion battery is cut along a reference surface provided on the holding tool, and an observation cross section (42a) orthogonal to the positive electrode plate and the negative electrode plate is formed. Further, the active material removed from the battery network is removed by the cutting process, and a deformable transparent filler is filled between the transparent plate and the observation cross section. At the time of observation, illumination light is projected through the transparent plate and the transparent filler toward the observation cross section of the lithium ion battery structure, and an image of the observation cross section of the lithium ion battery structure is taken. [Selection] Figure 9