Originally Posted by dougingraham
They don't actually swell and contract during normal operation.
I'd go along with that. The cylindrical cells, including those from A123, don't allow any significant swelling, otherwise the case would rupture. I've dissected a couple of cylindrical Lifebatt cells, and there's no space for expansion inside. The "jelly roll" completely fills the casing. All they have is a small vent on the end cap to allow the electrolyte to boil off in case of overcharging/overheating.
Having said that, I do remember CroDriver saying that these cells must be clamped together and he has plenty of experience with them. Has anyone monitored pouch cell thickness during a typical charge/discharge cycle?