Don't the forces of the individual cells add up when they are clamped together? Only one cell is ever considered in the specifications. If they were clamped with 300 kgf and each individual cell generated a counterforce, the counterforce of the clamping device would have to be n * 300 kgf, wouldn't it?
But that would destroy the cells. On the other hand, several cells together could exert a much higher force than the 300 kgf intended for one cell.
No. There's a long discussion on this somewhere else (perhaps even this thread) about it. It can be a tricky concept to grasp, but that's not how physics works.
I will try to explain kin simple terms. If we consider a row of cells clamped together, large-face to large face (typically 4 8, or 16 cells, with a non-compressing additional insulator 'dividers' added between each one), the cells are all in a relatively fixed position, with only small amounts of expansion changing the total "length" of the structure. (That "length" is actually the sum of thickness for"n" individual cells, plus "n+1" dividers).
You are remembering that a force, if not balanced by a "counter force", will (in Newtonian theory, not modern theory) will cause the target to be accelerated, the amount of acceleration determined by the famous formula "f=ma".
But in this row of cells, after a tiny bit of compression has occurred, the force at the large face of each individual cell is not causing acceleration (increased movement over time, within the same frame of reference). The force is instead felt through the thickness of the cell, and opposed (or "countered" by that same amount of force being applied FROM the "back" face of this cell, through the divider, and into the "leading" face of the next cell. This transmission of force continues through the entire row, until the last cell presses its "back" face into the opposite side of the containing structure - again with equal force as the first cell "felt", while the cells are not being accelerated or collapsing/expanding in response to pressure changes.
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Within a spring-loaded "single row" containment structure of the type discussed here, each cell feels the entire force compressive force being applied at the "face" of the first cell, ultimately countered by the "back" of the last cell pressing against the opposite end of the containment.
The "V3" specification sheet for EVE LF280K cells recommends that clamping be applied at a rate between 3000 Newtons and 7000 Newtons. The specification also indicates that they will collapse if more than 10,000 Newtons occurs. The very high maximum "recommended" clamping, a value of about 28 PSI, might allow for the design of non-sprung "fixed" containments (using the provided expansion rates in calculations). But the total expansion within a large "fixed" containment, e.g. 16 cells per row, would probably exceed the new and higher maximum limit. I haven't done those calculations, I continue to use spring-loaded clamping devices.