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The Galaxy Z Fold 8's batteries won't explode — Samsung's secret tech will make sure of it

The Galaxy Z Fold 8 series features silicon-carbon batteries, the first ever used in a Galaxy device to date. But are they safe?

By Mariyan Slavov

Published: Sep 03, 2026, 8:24 AM

Samsung

Galaxy Z Series

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Samsung didn't just slap some silicon inside the batteries of the Z Fold 8 series. The company changed the whole battery architecture. | Image by PhoneArena

The Galaxy Z Fold 8 series features silicon-carbon batteries, the first ever used in a Galaxy device to date. The adoption of silicon-carbon tech in the Z Fold 8's batteries was a step forward and a change I've been waiting to happen for a long time.

But Samsung didn't just slap some silicon inside the batteries of the Z Fold 8 series. The company changed the whole battery architecture to accommodate this new tech. And make it safer.

What is a silicon-carbon battery?

Samsung hopped on the silicon-carbon battery train with the Galaxy Z Fold 8 series. | Image by PixaBay

Silicon-carbon batteries employ mostly the same chemistry as normal lithium-ion batteries. The bump in capacity comes from using a silicon-carbon mix on the anode material, rather than relying on graphite.

Brands like Xiaomi and Honor often cite 10% silicon content in the anode, with the latest generations bumping up that number to 16%. However, as energy-dense as silicon might be, using it in batteries comes with risks.

The material expands and contracts significantly during charging and discharging, which can lead to battery swelling, short-circuiting, and, in the worst-case scenario, thermal runaway and explosion.

Samsung took these risks quite seriously and had to change the battery architecture inside the Galaxy Z Fold 8 series.

Would you consider buying the Galaxy Z Fold 8 just for the battery upgrade alone?

2 Votes

Samsung reengineered the batteries inside the Galaxy Z Fold 8

This won't happen to your Galaxy Z Fold 8. | Image by Clemson University

The company had to reengineer the battery tech inside its foldables basically from scratch. Samsung used a special carbon coating over the silicon to keep reactive particles at bay. The same method was used on the cathode as well, along with a technique called "cathode doping."

This involves injecting specific elements into the cathode crystal lattice, and not unlike sports doping, these elements help improve the cathode's performance.

On the anode side, a thin carbon coating helps manage the reactivity of silicon-carbon particles, helping mitigate sudden volume changes during charge and discharge and supporting long-term stability. On the cathode side, coating and doping help maintain surface stability and structural integrity, even under higher voltage conditions.

- Samsung on the Galaxy Z Fold 8 battery

Elements like aluminum (Al), titanium (Ti), or niobium (Nb) are doped into the cathode lattice. These hard elements help stabilize the crystal structure, prevent microcracking from expansion, and stabilize the surface at high voltages.

Read more articles about battery tech here:

More magic has been added to the battery electrolyte

Cathode doping makes the battery more resilient. | Image by Gemini

The changes Samsung had to make don't stop with the electrodes. The company says it had to reengineer the electrolyte too — the separator between the anode and the cathode. Samsung cooked up special additives to "help form a protective layer on the silicon surface, reducing silicon reactivity and supporting long-term cell stability."

Tweaks have been made to the separator — the sheet between the two electrodes. Samsung used a porous material to improve ion transport and maintain thermal stability. The Galaxy Z Fold 8 Ultra got most of these changes, as the regular Z Fold 8 was "separately optimized for the unique spatial and thermal requirements."

The compact foldable retains most of the battery and charging characteristics of last year's generation.

The Galaxy S27 series will get silicon-carbon batteries

Galaxy S27 line to get silicon-carbon batteries, along with the new design. | Image by IceUniverse

Now that Samsung has finally come aboard the silicon-carbon train, good things are coming our way. The Galaxy S27 series is due in a couple of months' time, and given it's September already, units must be in production by now.

I'm positive the Galaxy S27 series will have a silicon-carbon battery, and it will be the first battery upgrade for the Ultra, full stop. Ever since its inception back with the Galaxy S20 Ultra, the battery capacity has been fixed at 5,000 mAh, sparking frustration among Samsung fans.

Now, as Samsung polishes silicon-carbon tech, I expect a 6,000-ish mAh battery inside the Galaxy S27 Ultra and faster charging too. Are you excited about the upcoming Galaxy S27 Ultra? Would you consider buying one just for the battery upgrade alone?

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Mariyan, a tech enthusiast with a background in Nuclear Physics and Journalism, brings a unique perspective to PhoneArena. His childhood curiosity for gadgets evolved into a professional passion for technology, leading him to the role of Editor-in-Chief at PCWorld Bulgaria before joining PhoneArena. Mariyan's interests range from mainstream Android and iPhone debates to fringe technologies like graphene batteries and nanotechnology. Off-duty, he enjoys playing his electric guitar, practicing Japanese, and revisiting his love for video games and Haruki Murakami's works.

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