Samsung SDI is pushing the boundaries of mobile battery technology with ambitious tests on massive Silicon-Carbon cells. Internal test reports that leaked on X reveal the company is actively developing 12,000mAh and 18,000mAh battery packs. These are not your typical smartphone batteries. The reports also mention a 20,000mAh variant, though details on that unit remain scarce.
The testing data exposes some real challenges. Both the 12,000mAh and 18,000mAh batteries failed after 960 charge cycles. That is well short of the 1,500 cycle target. Samsung SDI is clearly still working through the durability issues that come with packing this much capacity into a mobile form factor. The company continues testing to see if these cells can reach their longevity goals.
The 12,000mAh battery, designated SDI-DC12K-SiC-V2, uses a dual-cell architecture. It combines one 6,800mAh cell measuring 4.7mm thick with a 5,200mAh cell at 3.2mm. The target stack thickness is under 9.3mm, though manufacturing variance caused 2 out of 7 test samples to exceed this limit. Meanwhile, the 18,000mAh battery (SDI-TC18K-SiC) takes a triple-cell approach with layers measuring 4.2mm, 3.9mm, and 3.28mm. The design aims for 12.3mm total thickness, but thermal interface layers pushed test units to 12.8mm.
Test reports for the 12,000mAh and 18,000mAh Si-C batteries from Samsung SDI
Test notes indicate Samsung SDI plans to redesign the internal layering and stacking methods. The company is also refining battery management firmware to handle these larger cells. Performance projections look promising despite the setbacks. The 12,000mAh unit could deliver 20 to 25 hours of screen-on time over 4G and Wi-Fi. Samsung optimized this variant for stability. The 18,000mAh version prioritizes raw capacity and endurance over everything else.
Individual cell specs suggest these technologies could trickle down to regular smartphones. A standalone 6,699mAh 4.2mm cell would fit nicely in a flagship device. Early speculation suggested the Galaxy S26 Ultra might debut with Silicon-Carbon technology, but that did not happen. The Galaxy S26 series launched without these advanced batteries. Looking ahead, the S27 Ultra might be the first to benefit if Samsung SDI resolves the remaining issues. Foldable phones would also gain significantly from thinner, higher-capacity battery solutions.
Source | Via