Battery Management Systems for Large Lithium-Ion Battery Packs
Section 220.127.116.11.2 Addenda
Whether cell expansion should or should not be contained is up for debate. The goal is, of course, to maximize the performance of the cells, including their cycle life. On one side, containment may harm cells because the active material does expand and must be allowed to expand at high SOC levels. On the other side, allowing a cell to expand may harm cells as the deformed cell is not able to regain its original shape, resulting in delamination.
Given these contrasting requirements, I cannot give you a fast rule on containment. Guidance on containment for a particular cell should come from that cell's manufacturers; yet, I cannot find any such guidance.
My sense is that batteries should be built with cells at mid-SOC levels, and should be bound but not squeezed, using materials with some compliance.