Hello
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Which Batteries can I use for Corebook X 14 - Laptops / CoreBook X - CHUWI | Official Forum
There are some in there but as I said, increase of capacity is not for sure.
I would say, that if you really need to extend battery duration, a Good Powerbank with PD higher than 65W may be a good option. They are not that cheap but will cover charging not only the laptop but other devices when needed.
Regards