- Samsung is reportedly testing a 20,000mAh phone battery
- The increase in capacity is thanks to a silicon-carbon compound
- It is unlikely to be ready in time for the Galaxy S26 series
Battery capacity is one of the most important specifications that most of us look for when buying a top smartphone, and it’s rumored that Samsung is working on a significant upgrade in this department – even if it won’t arrive in time for its next flagship phones.
According to tipsters @phonefuturist and @SPYGO19726 (via Wccftech), Samsung is testing a dual-cell silicon-carbon battery that goes as high as 20,000mAh. That’s four times the capacity of the 5,000mAh battery inside the Samsung Galaxy S25 Ultra.
As you might guess from the name, silicon-carbon batteries differ from the conventional lithium-ion batteries inside today’s phones in the choice of materials. A silicon-carbon composite anode enables much higher capacities without too much increase in bulk.
We’ve heard whispers of this silicon-carbon technology before, including in a leak from earlier this year, which suggested that next-gen batteries could be ready in time for the Galaxy S26 series – although that now looks unlikely to happen.
Coming soon
Some additional size details about the dual stacked cell Cell 1 (Primary): Capacity: 12,000 mAh Thickness: 6.3 mm Dimensions: 10 cm × 6.8 cm Cell 2 (Secondary / Competitive Stack): Capacity: 8,000 mAh Thickness: 6 mm H × 0 cm. swell from 4 mm to 7.2 mm. https://t.co/xVRA4Th3Hk25 December 2025
While the 20,000mAh battery now in testing certainly sounds promising, it’s not clear exactly when it will be ready for mass production. According to this leak, there are still swelling issues that need to be addressed.
Samsung knows what it’s like to have battery technology go wrong, and it won’t repeat these mistakes again. Both Samsung and its competitors will wait until the silicon-carbon upgrade is completely ready before pushing it out.
With that in mind, don’t expect much in the way of upgrades for the Galaxy S26 phones due to ship in February. Based on recent leaks, we might see a slight bump up to a battery capacity of 5,200 mAh for the Samsung Galaxy S26 Ultra model, for example.
However, it’s encouraging to know that big increases in battery capacity are on the way – and within the next year or two we might have the privilege of using phones that last two or three days between charges.
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