The battery is the same one used in the exploding Galaxy Note 7.
iFixit's regular smartphone teardown has revealed the internal components of the Samsung Galaxy S8 are almost identical to the Note 7's, including its battery.
“The Samsung Galaxy S8+ battery voltage, capacity, and design tolerances are virtually identical to the Note 7,” the teardown report said. “Our unit’s battery even came from the same manufacturer as some Note7 batteries. The design surrounding the battery – its installed position, spacing, and reinforcement – is very, very similar to the Note 7.”
However, this doesn't mean Samsung's flagship is going to explode like the Note 7, because the company has implemented a strict testing process to avoid a repeat of the debacle.
iFixit has also noted other parts of the Samsung Galaxy S8 are identical to the Samsung Note 7, including the construction of the antenna and its integration with the NFC/wireless charging panel and front-facing camera with iris scanner.