Not familiar with the CHUWI corebook (full disclosure) so I googled it and found the following link:
https://www.notebookcheck.net/Chuwi...e-a-Huawei-MateBook-But-Cheaper.548269.0.html
Far more than you asked for and perhaps needed to know.
I had to scroll to the very end to find information regarding battery and power. Not much there....
You may or may not be able to buy or otherwise obtain a suitable replacement battery. OEM or otherwise.
Plus "somehow fit it [replacement battery] in to the laptop" may be quite problematic in any number of ways.
Write down the battery's part number and specs. Then google accordingly. You may find other sources for the battery be they original OEM or generic.
Overall all, my sense is that you will need a replacement battery sooner rather than later. Having a spare battery on hand may be a solution of sorts.
Just my thoughts on the matter.