Why Apple and Samsung Are Skipping Silicon Carbon Batteries

Tech reviewer Marques Brownlee recently held up two phones that tell you everything about the current state of smartphone batteries. One was an iPhone 17 Pro Max with a 5,000 mAh battery. The other was the Honor Power 2—an iPhone clone, yes, but thinner than Apple's device while packing a 10,000 mAh battery. Double the capacity in less space.

The technology making this possible is silicon carbon batteries, and they've been commercially available for about three years now. Companies like Xiaomi, Oppo, Huawei, and Honor have shipped them in volume. OnePlus jumped from 5,400 mAh to 7,300 mAh in a single year using the technology. The benefits are straightforward: silicon holds more energy than graphite, so you can pack more battery into the same footprint.

Yet Apple, Samsung, and Google haven't touched it. Their latest flagships still use conventional lithium-ion batteries. The initial explanation seemed obvious enough—supply constraints. When you're Apple ordering batteries for tens of millions of iPhones, maybe the manufacturing capacity just isn't there yet.

That theory doesn't hold up. Google ships far fewer Pixels than Xiaomi ships phones, yet Xiaomi uses silicon carbon throughout its flagship line. The volume argument only works if everyone avoiding the technology is operating at massive scale, but that's not the pattern we're seeing.

The Physics Problem

Brownlee's reporting points to a different issue, one he learned about through industry sources who reached out to him independently: silicon carbon batteries swell.

All batteries expand and contract during charging. It's basic thermodynamics. But silicon behaves differently than graphite. During charging, as silicon absorbs lithium ions, it can expand to three times its original volume. Brownlee puts it plainly: "Imagine a sponge that triples in size when wet and then shrinks back down and then over and over again every time it charges and discharges. Eventually things are probably going to crack."

The solution involves grinding the silicon into fine particles and using carbon as a buffer material to absorb the expansion—hence "silicon carbon." But this is tuning, not solving. Companies pushing higher silicon percentages to squeeze out more capacity are also pushing closer to mechanical failure. According to Brownlee's sources, some devices include literal steel cages around the battery to contain the swelling.

When the silicon structure cracks from repeated expansion cycles, you're looking at internal battery damage. Worst case is thermal runaway—the polite term for a battery fire in your pocket.

The Testing Gap

Manufacturers routinely test batteries through a thousand charge cycles, demonstrating 80% capacity retention. That sounds reassuring until you consider everything else a battery experiences in real-world use: temperature swings, drops, pressure changes, humidity. The list is long and the interactions are complex.

Brownlee cites a source who mentioned getting failure rates down to one in 250,000. That's excellent reliability by most standards. But when you're shipping 50 million phones, that's 200 potentially catastrophic failures. Samsung learned this lesson with the Note 7 in 2016. Apple watched it happen and took notes.

"Since there isn't quite enough real world data yet, especially over longer periods of time, some companies are choosing to just sit it out for now," Brownlee explains.

That's the conservative play, and it makes sense for companies with long memories and huge production volumes. The first silicon carbon phones appeared three years ago, but volume didn't ramp up until the past year. We're still in the early innings of understanding how these batteries age under varied conditions.

The Market Dynamics

There's another factor worth examining: the companies avoiding silicon carbon all have significant U.S. market presence, and the U.S. market operates differently.

American consumers largely choose phones based on ecosystem lock-in, not hardware specs. iMessage creates switching costs that a bigger battery won't overcome. The blue bubble phenomenon is real enough that hardware innovations matter less here than in markets where people use WhatsApp and can switch phones freely.

Brownlee frames it directly: "If people aren't going to buy the new iPhone because of a silicon carbon battery or they're not switching off of the iPhone because of some other phone silicon carbon battery, then there is no reason for Apple to take that risk yet."

In markets with genuine hardware competition, a 40% battery capacity advantage moves units. In the U.S., it's a spec sheet line item that most buyers won't notice.

This creates a split in how companies approach emerging battery technology. If you're competing on hardware in Asia, you adopt silicon carbon quickly because standing still means losing customers. If you're competing on ecosystem in America, you can afford to wait for more data.

What Happens Next

The technology is deployed now. Millions of phones with silicon carbon batteries are aging in pockets worldwide. We'll know within the next year or two whether the swelling concerns are manageable quirks or fundamental problems.

If these batteries age well, the holdouts will look overly cautious. If they don't—if we start seeing swelling issues or worse—then Apple and Samsung will have made the right call waiting for more real-world data.

I've covered enough technology cycles to know that "bleeding edge" cuts both ways. Silicon carbon batteries represent genuine innovation in energy density. They also represent material science challenges that don't resolve themselves on quarterly timelines. The companies shipping them now are either confident in their engineering or willing to accept risks that others aren't.

The companies sitting out are betting that ecosystem strength buys them time to let others do the long-term testing. That's not conservative. That's just having options.

—Bob Reynolds, Senior Technology Correspondent