Xbox one S "dreamgear battery/pack" how does it charge?

Excuse my ignorance...

I got a military green xbox one s off off ebay... Decent decent price.

Came with one controller but it was missing the typical battery lid/cover and instead had this "dreamgear" battery pack... which i assume is rechargeable. However.. does it need a specific charging station? I have tried to plug a regular usb cable to the controller while the battery pack is plugged on it it ofcouse and it does not charge. The controller worked for a few days so i thought the battery would recharge... So dont know if all of a sudden the battery just died (i left it on full night plugged to a usb 3 aukey quick charger) and i have not been able to recharge it ever since.

Any ideas?
Or i might just as well buy from ebay a battery lid and just get regular AAs?