@ Rémi Friess the battery in my D-808 is Xhdata branded 2000mA
@ Kenny Murray i use vaping gear and i have a lot of 18650 batteries but keep in mind that most vaping gear (if not all) use flat-top batteries while you need button-top.
Flat-top batteries are shorter and you can adapt them using one of those Neodymium magnets sold on ebay or aliexpress , see https://www.ebay.co.uk/itm/321296194078 or https://www.aliexpress.com/item/32792488474.html
The good point is that vaping gear draw a lot of current and use batteries rated 25A minimum; most are rated 35A. You do not need high current batteries for your radio, you need high capacity, however you can be sure that if the battery is good for vaping it is good quality (still need the magnet extension) or it will not work at all.
In "normal times" quality batteries can be purchased online for less than $3 each from China including shipping but nowadays with Covid-19 most sellers apply huge shipping charges.
I use these for my vaping gear https://www.aliexpress.com/item/32821524948.html and they are as good as the famous brands.