Samsung has adopted silicon-carbon battery technology for the first time, using the higher-density cells across its new Galaxy Z Fold 8 Ultra, Galaxy Z Fold 8 and Galaxy Z Flip 8, which were officially unveiled this week.

Silicon-carbon batteries remain a form of lithium-ion technology, but replace part of the conventional graphite anode with silicon. This allows manufacturers to store more energy in the same physical space or maintain battery capacity while reducing a device’s thickness and weight.

That is particularly useful in foldable phones, where the hinge and folding display occupy internal space that could otherwise be used for a larger battery.

The Galaxy Z Fold 8 Ultra (below) carries a 5,000mAh battery, up from the 4,400mAh cell fitted to the Galaxy Z Fold 7, despite being slightly thinner when unfolded.

The standard Galaxy Z Fold 8 has a 4,800mAh battery, while the Galaxy Z Flip 8 (below) carries a 4,300mAh unit.

Samsung used the denser battery technology to reduce the Flip 8’s folded thickness from 13.7mm to 13.1mm without cutting capacity.

The figures remain below several Chinese-owned rivals. Honor’s Magic V6 has a 6,660mAh battery, while Motorola’s Razr Fold offers 6,000mAh.

Samsung said it had taken a conservative approach focused on performance, longevity and safety rather than chasing the largest possible capacity.

The company declined to disclose the percentage of silicon used in its batteries but said the amount was consistent across all three foldable models.

Samsung also reworked the electrolyte, separator, cell structure and expansion controls to manage silicon’s tendency to expand and contract during charging.

It said charging-cycle performance and battery lifespan should remain consistent with previous Galaxy devices, although those claims are yet to be independently tested over the long term.

The Fold 8 and Fold 8 Ultra also support 45W wired charging and 20W wireless charging.

The launch could pave the way for silicon-carbon batteries to appear in Samsung’s Galaxy S and lower-priced Galaxy smartphone ranges.