Welcome to the club!
The only advice I’d offer is, before you risk your hard-earned money buying one, go out into your local world & find a computer repair store — preferably a small “mom-&-pop” store — for some “practice dummies”, i.e. “dead” packs. Ask to speak with the owner or service manager on duty. Explain to them how you’re trying to recycle “dead” laptop batteries for the cells inside. Take a flashlight to show off if you want to. Even explain that normally the cells are fine, the pack has died because the protection circuit has failed. Or don’t but it helps to make sure they understand you will diligently follow all laws and codes and will recycle each tiny piece with gusto.
Normally, they’ll likely have a box half-full of them. If they let you pick, start with the cleanest, newest one (likely less abused) and take as many as they will let you.
Computer service managers are an intelligent, curious, friendly bunch and mostly bored on the job, so the off-the-wall visit and some relevant-but-largely-useless information might be appreciated. But they do have bosses so be sensitive to their time. Speaking of time, it would be best to go by when their parking lot is empty…
If you like Engineering, you can practice it here by profiling the pack manufacturers vs. the cells inside, vs. those cells’ performance. Now you will have the answer to your question.
No cost but gas money. And the chance to make a friend.
Yes.
The important fact to remember is, the bigger the buyer the better the buy. Look to the top laptop sales leaders & try those. I see you’re looking to find which pack might contain what cells, so I apologize for not having a clue about that. Years ago, “the trades” were pulp magazines that published stuff like production numbers and who’s doing what with whom, but I’m sure there’s a WWWeb site for that now.
Packs for older models tend to have lower-capacity, older cells; newer packs, vice-versa, obviously.
Perhaps you could start by deciding how much you’re willing to spend on a new pack & then finding the newest Dell, Alienware or HP laptop whose battery costs ‘that’ much. Whatever cells you get will make you happy.
That’s an obvious algebra equation, IFF you know the Parallel/Series relationship of the cells, and the number thereof, in the individual pack in question. Parallel multiplies V, Series multiplies mAh.
There’s an easier way. The individual cells are marked with codes, which you can Google or bring here. That will give you the same Capacity number, easier.
Or perhaps you’re trying to pick which pack you buy based on its mAh rating. I’d bet the farm that the deepest number on all packs of x Volts would have the deepest cells inside. As long as you don’t expect to actually see that mAh from any of them, that should get you the deepest available.
I’d really like to see you take a pack — bought new or not, and profile all the cells in it; to see how closely they are to A: each other and B: the published spec for that cell. I’m going to wager you don’t see any two the same.
As for me, I’m not picky over fist-fulls of free batteries, but my work puts more Dell packs in my hands than any other. The newer Dells have some nice 18650s in them (e.g. ) LGABC11865 (“2800 mAh”) and SE US18650GR.

YM, of course, MV, but you could start with a pack for the newest Dell Inspiron…
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Dim