I replaced the stock battery in my Note 10.3 with a replacement battery from Aliexpress. The stock battery is 4100mAhr, the replacement is 6800mAhr(!).
Same physical size, but the replacement battery has a tiny circuit board (I assume to help manage the battery charge better - the stock battery had none, probably why the battery crapped out in just over 2 years).
Soldering skills are necessary(!), I am not great, but with a bit of liquid flux, I tinned the wires on the motherboard and soldered the battery wires to them - it worked out.
The stock battery is held down with two strong adhesive strips, if you pry carefully the adhesive stays on the gray subframe and not the battery - be careful to pry only where the gray subframe is.
I had to bend the three wire leads carefully so they would not be pinched by the raised ridge of the gray subframe upon reassembly.
My Boox back case was already cracked in 2 corners and chipped in a third - it is a design weak point - be prepared for case damage if you try to take the case off for battery change.
Photos here:
https://photos.app.goo.gl/nDqRWJTb43D9vsTT9
Battery link is here, I can't vouch for the safety or ultimate compatibility, but the battery is the same size.
https://www.aliexpress.com/item/3286...36214c4dTymZV7