system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why do batteries work again after heating them up?

Sometimes if a remote or some other small electronic stops working because the battery is dead, I take the battery out and heat it up by putting it in my arm pit. The warmth heats up the battery and give it a little more juice allowing me to use it again for a minute. I also remember doing this with old mobile phones in the early 00s and it would let you turn on a dead phone and use it for a few minutes. 

I have no idea how this works and don’t remember where I learnt how to do this.
gpt
You’re not necessarily recharging the batteries. But heat makes batteries more efficient/effective. Batteries have a chemical solution inside them that stores electrons. When the temperature of the battery is low, the chemical processes inside the battery is slower meaning the movement of those electrons is also slower. When you warm up a battery, you’re able to speed all of that up. When you put the batteries back in the device, that manifests as a minute or two of extra charge. But you haven’t actually added any more electrons (or at least not enough to be meaningful) to the battery, the electrons just move more efficiently & electricity is just electrons in motion.

Edit: rewrote the last phrase to make it make sense. Sorry for the autocorrect confusion.