https://wccftech.com/galaxy-s21-could-launch-with-batteries-from-a-chinese-supplier/

Based on the latest tip from an insider, the Galaxy S21 series could be using batteries that are sourced from a Chinese manufacturer called Amperex. However, in addition to batteries being sourced from Amperex, Samsung SDI is also going to be supplying batteries in this mix.

In the world of smartphone manufacturing, the concept of outsourcing components is nothing new. Every smartphone there has some part of it outsources. Everything ranging from cameras, displays, to batteries are more often than not, outsourced. Samsung does it, Apple does it, and so does every other smartphone manufacturer.