iPhone 17 Air may debut advanced silicon battery for more efficient charging

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Apple's iPhone 17 Air may last longer on a charge that it would with existing tech, thanks to silicon batteries that pack 15% more energy into the same space.

Two iPhones with multiple lenses on the back, one silver with three lenses and another pink with two lenses, displaying the Apple logo.
iPhone 17 Air render on the right



The iPhone 17 Air, expected this fall, could be the first Apple smartphone to feature advanced silicon-anode battery technology. Japanese supplier TDK has confirmed that it's accelerating production, with shipments set to begin by the end of June.

That timeline may give Apple just enough lead time to include the new batteries in its rumored 5.5mm-thin device, according to DigiTimes. The thin model is widely expected to be announced in September.

TDK's silicon-anode batteries store about 15% more energy in the same physical space compared to conventional graphite-based batteries. The extra density is possible because silicon can hold more lithium ions per gram than graphite, making it ideal for devices where every millimeter counts.

Apple shifts strategy by adopting new battery chemistry



For Apple, adopting silicon battery tech would mark a significant shift in its battery strategy. The company has historically prioritized chip and software efficiency to extend battery life, avoiding big changes to internal battery chemistry.

The move would be one of the first times Apple brings a major material change to iPhone batteries, signaling that silicon-anode tech is finally ready for mass production.

To put the rumored design in context, current iPhones measure around 7.8mm thick. If the iPhone 17 Air comes in at 5.5mm, that would make it the slimmest iPhone ever and one of the thinnest modern smartphones overall.

Making a phone that thin without compromising battery life is a challenge Apple appears ready to take on.

A broader push toward silicon batteries



Silicon-anode batteries have been in development for years, with startups like Sila and Amprius working to bring them to scale. Apple entering the picture suggests the technology has matured.

The material is appealing for next-generation batteries because it can store up to ten times more lithium ions per gram than graphite, allowing for much higher energy density. That's especially valuable in thin devices like smartphones, where space is limited.

The challenge is that silicon expands and contracts dramatically during charging, which can cause cracking and early battery failure. To overcome this, companies like TDK use engineered silicon composites rather than pure silicon. These materials blend silicon with flexible binders or coat it in nanoscale layers to reduce stress and maintain structural integrity.

Three iPhone 17 Airs in gold, white, and green float above a gradient background, displaying their rear cameras.
The iPhone 17 Air could serve as a testing ground



The result is a battery that offers more power without sacrificing durability. The battery innovation may also tie into Apple's longer-term hardware roadmap.

The iPhone 17 Air could serve as a testing ground for these materials at a large scale. TDK is already working on fourth-generation silicon batteries for future products. If the rollout in the iPhone 17 Air is successful, Apple might adopt this technology in other devices.

The thin iPhone is expected to replace the Plus model in Apple's 2025 lineup. With a 6.6-inch display and a dramatically slimmer design, it's aimed at users who want a lighter phone without giving up modern performance.

If the silicon battery delivers on its promise, it could reshape expectations for thin smartphones and give iPhone users more power in less space.

Rumor Score: Possible

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Comments

  • Reply 1 of 4
    thttht Posts: 5,954member
    Sounds crazy to use a new battery chemistry on a thin iPhone, and one with a silicon anode to boot. 

    Thought one of the issues with silicon anodes was they expand more, and battery casings need to account for this. A thin battery with silicon anodes sounds challenging here?
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  • Reply 2 of 4
    yyzguyyyzguy Posts: 61member
    Are people really clamoring for thinner phones at the expense of battery life?   I foresee a market opportunity for battery cases.   I added one myself to iphone mini 13.
    williamlondon
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  • Reply 3 of 4
    avon b7avon b7 Posts: 8,287member
    tht said:
    Sounds crazy to use a new battery chemistry on a thin iPhone, and one with a silicon anode to boot. 

    Thought one of the issues with silicon anodes was they expand more, and battery casings need to account for this. A thin battery with silicon anodes sounds challenging here?
    I think things have become clearer now that we are on third or fourth generation silicon carbon batteries in smartphones and there have been no major issues. Over ten Android manufacturers are currently using them today. 

    Huawei developed a silicon carbon design back in 2018 and filed patents for it in June 2019.

    https://www.grepow.com/industry-news/Silicon-Carbon-Composite-Material.html

    Manufacturing is typically outsourced to TDK. 

    "Huawei high silicon anode battery

    Huawei has made significant progress in the field of battery technology, especially in the research and development of high-silicon anode batteries.
    ...
    Huawei has improved the conductivity and stability of the silicon anode by optimizing the material ratio and microstructure. It has also solved the problem of volume expansion of silicon materials during charging and discharging, and improved the stability and cycle life of the battery.
    ...
    Huawei’s high-silicon negative electrode battery has received positive reviews from the market for its technological innovation and performance improvement. This battery not only improves energy density, but also achieves a breakthrough in battery capacity without a significant change in volume. Huawei uses carbon coating structure and innovative flexible polymer binder to inhibit expansion and shedding; uses lithium foil to supplement lithium, which increases the first charge and discharge efficiency by 26%; uses nano-carbon tube technology in silicon negative electrode batteries to increase conductivity by 4 times, further improving the performance of silicon negative electrode batteries."

    https://www.epic-powder.com/market-darling-silicon-carbon-anode-battery/

    On the heat management side, Huawei has also made great progress with its graphene solutions. 

    I've already mentioned this is previous threads but if Apple really wants to go thin (and I mean really thin batteries of less than 2mm thick), silicon carbon would be a very strong candidate. 

    A good move. 
    edited May 16
    muthuk_vanalingamjbirdiikunAlex1N
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  • Reply 4 of 4
    charlesncharlesn Posts: 1,483member
    This is the most interesting thing I've heard about the Air/Slim so far. Up til this point the sales pitch as been, "Get a phone that's 2mm thinner for a bunch more money and, oh, by the way, you'll lose mmWave 5G and get the same camera used on the economy-class iPhone.
    jbirdiikunAlex1N
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