Galaxy Z Fold 8 Silicon-Carbon Battery: More Capacity, Fewer Cycles
Samsung’s Galaxy Z Fold 8, Galaxy Z Fold 8 Ultra, and Galaxy Z Flip 8 are the first Galaxy phones to use silicon-carbon batteries. Samsung confirmed the change to reporters at the July 22, 2026 launch, even though the spec sheets do not mention it. The new cells let two of the three phones carry more capacity or a thinner body. They also come with a shorter rated lifespan, and that trade-off is the part most coverage of the launch skipped.
What Changed in the Three Phones
| Fold 8 | Fold 8 Ultra | Flip 8 | |
|---|---|---|---|
| Battery capacity | 4,800mAh | 5,000mAh | 4,300mAh |
| Previous model | Fold 7: 4,400mAh | Fold 7: 4,400mAh | Flip 7: 4,300mAh |
| What the new cell allowed | Larger battery in a smaller body than the Fold 7 | Larger battery in a thinner body (4.1mm unfolded) | Thinner when folded (13.1mm vs 13.7mm) |
The Fold 8 is a new, wider design, so its comparison with the Fold 7 is a comparison of different shapes. The Fold 8 Ultra is the direct successor to the Fold 7. The Flip 8 kept its predecessor’s capacity and used the denser chemistry to shave thickness instead.
How Silicon-Carbon Cells Work
Conventional lithium-ion cells use graphite for the anode, the side that holds lithium ions while the battery is charged. Silicon-carbon cells replace part of that graphite with silicon, which can hold more lithium for the same volume. That is why manufacturers can fit more capacity into the same space or keep capacity and make the phone thinner.
Silicon has a known drawback: it expands and contracts as the battery charges and discharges, which stresses the cell over time. Samsung said it reworked the electrolyte, the separator, the cell structure, and the expansion controls to manage this. Samsung also described its approach as conservative, focused on safety and longevity rather than the largest possible capacity, which fits the modest capacity figures compared with some rival foldables.
Samsung is not the first phone maker to use the chemistry. Several Chinese brands have used silicon-carbon cells since around 2023.
The Trade-Off: Rated Cycle Life
EU energy-label (EPREL) listings show the Fold 8, Fold 8 Ultra, and Flip 8 are all rated for 1,200 charge cycles before the battery drops to 80% of its original capacity. The Fold 7 and Flip 7 were rated for 2,000 cycles.
Android Authority worked through the arithmetic. At 80% capacity, the Fold 8’s 4,800mAh becomes 3,840mAh, the Fold 8 Ultra’s 5,000mAh becomes 4,000mAh, and the Flip 8’s 4,300mAh becomes 3,440mAh. At one full cycle per day, 1,200 cycles is roughly three years. The older Flip 7 would take about five years to reach the same point.
Samsung’s own position is that charging-cycle performance and battery lifespan remain consistent with previous Galaxy devices. That statement does not match the EU listings, and neither claim has been tested independently over several years of use.
What This Means for Owners
- Capacity today is higher, lifespan is shorter. A new Fold 8 should last longer per charge than a Fold 7, and may need a battery replacement sooner.
- Charging habits matter more. Limiting charging to 80% with Samsung’s battery protection setting and avoiding heat are the practical ways to slow wear. See the Fold 8 battery settings guide for the settings.
- Long-term software support changes the math. Samsung lists up to seven major OS updates for the Fold 8 in some markets, so plan for a battery that may need service before the software support ends.
Sources:
- Samsung starts using silicon-carbon batteries with Galaxy Z Fold 8 series, Flip 8 (9to5Google)
- Samsung’s new silicon-carbon batteries in Galaxy Z Fold 8 won’t last as long (9to5Google)
- Confirmed: Samsung’s new foldables have major battery health downgrade (Android Authority)
- Why Samsung finally switched to silicon-carbon batteries for its new foldables (ChannelNews)
- Samsung debuts silicon carbon batteries with Galaxy Z Fold 8, Fold 8 Ultra, and Flip 8 (SamMobile)