How Samsung’s titanium-backed foldable display made room for a bigger battery

At a hardware briefing during Samsung Unpacked in London, the company’s engineers explained how a thinner display structure created room for a 5,000mAh silicon-carbon battery, and why the crease remains one of the next big problems to solve.

Foldable phones are a constant fight for space, like all smartphones I guess, but perhaps even more so given the technical challenges of the hinge – and that foldable glass!

Every component has to fit around a hinge, while leaving enough room for cameras, cooling, a large battery and everything else expected from a flagship phone. So when Samsung says it has made its latest foldable display structure around 10 per cent thinner, the real story is not simply that the phone itself can become thinner – even though it did.

It is what Samsung chose to do with the space it got back.

During Samsung Unpacked in London, I attended a hardware briefing led by Sunghoon Moon, EVP and Senior Executive, Mobile R&D Office – H/W, Samsung Electronics. Moon walked us through the engineering behind Samsung’s new Flex Titanium display structure, and how that one change connects to the hinge, battery, thermal design and the future of its foldable devices.

“Meaningful innovation cannot come from just optimizing one component in isolation,” Moon said.

“So, we re-engineered the whole system, including display structure, hinge and thermal design.”

That is really the core of Samsung’s pitch. Flex Titanium is not a titanium OLED panel. It is a new supporting structure beneath and within the foldable display, made up of two titanium-based elements that perform different jobs.

The first is a titanium plate beneath the display. It is designed to absorb pressure and shock, support the OLED panel and reduce unevenness across the screen.

Titanium is strong and resistant to permanent deformation, which makes it useful as a support structure. The problem, of course, is that a foldable display still needs to fold.

To get around that, Samsung has engineered a fine lattice pattern into the plate around the folding area. During the briefing, Samsung explained that the lower part of the lattice uses slightly larger holes created through wet etching, while the upper section uses much smaller laser-cut holes. And we’re talking tiny, almost microscopic holes here.

The idea is to give the centre of the plate enough flexibility to fold repeatedly, while retaining the rigidity needed to support the rest of the screen.

The second element is an ultra-thin titanium alloy film positioned within the display module.

Samsung says this film is only tens of micrometres thick, roughly one-third the thickness of a human hair. It is intended to support the panel without interfering with the folding motion, while reducing the small rises and dips that can appear across the surface of a flexible display.

Samsung refers to those imperfections as “undulations”. For the person using the phone, it should mean a flatter-looking screen, a less visible crease and a more consistent surface when viewing content.

But the biggest benefit may be the space Samsung says it has recovered behind the display.

“Flex Titanium technology reduced the display thickness by 10 per cent,” Moon said. “So it saved space for a larger battery and improved thermal design.”

A thinner display is only half the battery story

Samsung did not simply make the display thinner and fill the remaining space with a conventional battery.

The company has also moved to a silicon-carbon anode, which allows it to increase the energy density of the battery. In simple terms, Samsung can store more energy without increasing the battery’s physical size by the same proportion.

Moon said Samsung had to tune the rest of the battery around that new chemistry.

“We redesigned the cathode, electrolyte and separator, as well as the anode, to manage the high reactivity of silicon carbon,” he said.

That distinction matters. The larger battery is not the result of one engineering change.

Samsung says the thinner Flex Titanium display structure created more physical space within the phone. The silicon-carbon battery then allowed it to make better use of that space by increasing energy density.

Together, those changes have allowed Samsung to fit a claimed 5,000mAh battery into the Fold 8 Ultra while still making the overall device slimmer. Samsung is also introducing 45W charging to the Fold 8 Ultra and Fold 8, with charging systems designed around the internal layout of each phone.

This is the kind of connected engineering that is easy to miss when each specification is presented separately.

A thinner display sounds like a screen improvement. A silicon-carbon anode sounds like a battery improvement. More room for cooling sounds like a performance improvement.

Inside a foldable phone, however, all three are related.

Samsung has changed the material supporting the screen, used that to reclaim internal space, and then divided the benefit between battery capacity and thermal management.

The crease is improved, but it is not gone

Flex Titanium is also supposed to make the folding area flatter and reduce the visibility of the crease.

That does not mean Samsung has produced a crease-free display.

GadgetGuy’s Val Quinn asked whether the crease could eventually become completely imperceptible to touch. Moon did not give a date or make a firm promise that the crease would disappear entirely.

Instead, Samsung pointed to the work it had done over seven generations of foldable devices, including changes to the display structure, hinge and opening experience.

The company said its focus included “minimizing the crease visibility, achieving flat surface quality” and creating a smoother opening and closing experience.

Flex Titanium is part of that effort. The titanium plate is intended to absorb external force, while the alloy film supports the screen and reduces surface variation.

Samsung also says titanium’s ability to recover after being flexed helps improve long-term durability.

The company clearly believes the crease can become less visible and less intrusive. Whether it can disappear completely remains an open question. For what it’s worth, I think on the Fold8 Series it’s definitely an improvement, but perhaps not yet best in market – in terms of visible and perceptible touch.

Samsung says it is still excited about what comes next

Samsung has now produced seven generations of foldable phones, but the company does not sound as though it believes the form factor has reached its final shape.

I asked SH Moon whether he was still excited about what could come after the current generation, his answer was direct.

“We are currently working on various projects,” he said.

Through an interpreter, Samsung expanded on that answer, saying it was continuing to explore “how the device folds and what kind of technologies are incorporated into that experience”.

That is not confirmation of a particular future product. Samsung did not announce a tri-fold phone, a rollable display or another new form factor here, though they did include the Tri-Fold in their messaging about the generations of Foldables, and they did showcase rollable displays in a conceptual form.

Samsung’s advantage, according to Moon, is the information it has collected over seven generations of devices.

“At Samsung, we do not innovate for technology’s sake,” he said. “Every decision we make begins with understanding how people actually use their devices and what they expect from their devices.”

That is Samsung’s argument for why its foldable work is difficult to replicate. It is not based on one material or one breakthrough, but on years of changing the display, hinge, battery and body together.

Samsung has spent seven generations proving that a folding phone can work, they are using this moment in the spotlight to emphasise that as all eyes begin to look at what else is happening across the industry and who might next enter this foldable race.