According to leaked certification documents, the Galaxy S27 Ultra could feature a 5,700 mAh silicon‑carbon battery, a 14 % increase over the 5,000 mAh used in previous S Ultra models. This boost may finally give users the longer battery life they have been waiting for.

Since the Galaxy S Ultra series debuted in 2020, the battery capacity has stayed at 5,000 mAh for seven generations, meaning the line has not improved its endurance for years. Samsung’s cautious approach has kept the spec unchanged despite growing demand for longer use.

Silicon‑carbon batteries raise energy density by adding silicon to the anode, but silicon expands 280‑400 % during charging and can form dendrites, so manufacturers must apply special protective coatings. These technical challenges have slowed widespread adoption so far.

Chinese competitors already offer phones with 8,000‑9,000 mAh batteries that use silicon‑carbon technology, widening the capacity gap. Samsung has tested silicon‑carbon cells in the Galaxy Z Fold 8 Ultra, increasing its capacity from 4,400 mAh to 5,000 mAh.

The extra 700 mAh could enable more consistent two‑day battery life for users who play games, stream video, or run multiple apps, reducing the need to constantly manage power. If the rumor proves true, the S27 Ultra would mark Samsung’s first major battery upgrade in the flagship line.