Laptop battery comes back to life by freezing it?

[Jeroen3]

End 2009 I've bought a Dell Vostro 1520 laptop. Fantastic first laptop. With it came a battery.
In 2011, the original battery had only 20 minutes of the original 4 hours battery life left. So I bought a new one from eBay.
Unfortunately, I bought a "non genuine" one, which the laptop refuses to charge when you plug in the charger when it's off. It's charges fine when your plug in the charger after bios post.

So, don't drain it too low. It'll be fine. Battery lasts ~6 hours, it's the 6600 mAh one, with the bulge on the end.

Fast forward 3 years, and I've drained it. Won't turn on. Can't start charging. 
Somewhere on "the internet" I read that you could fix this by putting the battery in the freezer. So I did.
After 10 minutes in the freezer, behold, the laptop went through bios post and I could plug in the charger.

Now today, 6 years later, this battery still has 5 hours of battery life. However, the laptop is auxiliary and only used occasionally, by other people.
So I happened twice this year I had to redo the freezer trick to get it awake again after they've drained it.

Now, thinking about what I was actually doing I have two questions I can't find an answer to:
1. Why does this work? Does freezing the battery resets the battery management? Does it indeed raise the cell voltage?
2. Why was the old battery 80% worn out after 2 years, and the "non genuine" one only. Is this planned obsolescence?

"Non-genuine battery": 12% wear.
Design capacity: 73260 mWh
Last charge: 64810 mWh

"Genuine battery": 75% wear. (does not work anymore)
Design capacity: 57720 mWh
Last charge: 14830 mWh

Note: Freezing your batteries isn't something I can recommend. Condensation is a problem, and maybe even a danger.