If you keep them at about 50% and avoid temperature extremes, it doesn't take a PhD in electrochemistry. The thing is, fancy battery packs usually do contain active electronics that drain the cells slowly in storage, so it's necessary to charge them a little a couple times a year.
Yes, good idea. I do have a large freezer. Vacuum seal it, charge to 60% one time per year. Adjust charge interval to whatever remains after 12 months. It has to stay above 30%.