A tipster named phonefuturist claimed on Twitter that Samsung SDI tested a dual-cell silicon-carbon battery totaling 20,000mAh, composed of a 12,000mAh cell and an 8,000mAh cell.
The test reportedly delivered 27 hours of screen-on time and approximately 960 charging cycles over a year. Samsung SDI conducted this evaluation on the dual-cell configuration, which combines the two specified capacities to reach the overall 20,000mAh rating. The performance metrics emerged from this specific trial setup.
During the test, the 8,000mAh cell experienced swelling, increasing its thickness from 4mm to 7.2mm. Another tipster with a mixed track record provided this measurement detail. The swelling occurred by the end of the test period.
Battery Validation
Samsung SDI dual-cell Si/C battery (20,000mAh).
Cell 1: 12,000mAh @ 6.3mm
Cell 2: 8,000mAh @ 4mm
Results: 27h SOT, ~960 cycles over 1 year.
Post-test: cell swelling detected → longevity failure.
Strong short-term performance. Long stability still unresolved. pic.twitter.com/29Ldb6NJ4x— Schrödinger (@phonefuturist) December 25, 2025
This swelling indicates the battery would not endure long-term usage. As a result, a Galaxy phone equipped with a 20,000mAh battery remains unlikely in the near term. The leaker shared images purportedly depicting these batteries.
Recent flagship Android phones feature batteries exceeding 7,000mAh. HONOR recently launched models with 10,000mAh batteries. Chinese manufacturers offer devices in the 7,000mAh to 10,000mAh range.
Samsung SDI might be developing this core technology for automotive applications instead of smartphones. The dual-cell silicon-carbon design aligns with potential uses beyond mobile devices.
Silicon-carbon batteries gain capacity through higher silicon percentages. The OnePlus 15 includes a 7,300mAh battery with 15% silicon content, balancing capacity and reliability. A realme prototype features a 15,000mAh battery using 100% silicon content. Samsung SDI’s tested battery could incorporate a higher silicon percentage than those in commercial phones.
Some extra size detail about the dual stacked cell
Cell 1 (Primary):
Capacity: 12,000mAh
Thickness: 6.3mm
Dimensions: 10cm × 6.8cm
Cell 2 (Secondary / Competitive Stack):
Capacity: 8,000mAh
Thickness: 4mm
Dimensions: 10cm × 6.8cm
The 8000 MaH swole up from 4mm to 7.2mm. https://t.co/xVRA4Th3Hk
— S (@SPYGO19726) December 25, 2025
Details on the silicon content in Samsung SDI’s battery remain undisclosed in the leak. The configuration suggests exploration of elevated silicon levels to achieve the 20,000mAh total.
Efforts to verify include emailing Samsung SDI for comment on the claims and confirmation of whether the test targets smartphones. An update will follow any response from the company.
