A Silicon-Carbon Battery Could Have Rescued The iPhone Air

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Oct 23, 2025

o one ever said, “Geez, my iPhone is too fat; Apple better give me a razor-thin phone next time.” Yes, I’m talking about the iPhone Air, Apple’s manna for the fashion-obsessed vapid drones.

Disappointed with the uptake for its ultra-slim smartphone, Apple is already asking suppliers to cut the production of components for the iPhone Air by as much as 80 percent if Ming-Chi Kuo’s latest report is anything to go by.

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This is not a surprise outcome in hindsight. After all, the iPhone Air does have the lowest battery capacity in the just-released iPhone 17 lineup.

Yet, Apple could have easily avoided all the brouhaha around the iPhone Air’s gimped battery by moving a little out of its comfort zone for once, and opting for silicon-carbon batteries from the get-go. Sloth, thy brand is Apple.

Silicon-carbon batteries could have ensured plenty of juice for the iPhone Air, even with its slim form-factor

Two battery diagrams compare Graphite Anode at 372 MAH/G and Silicon Anode at 3579 MAH/G under Electrolyte label.
Image Source: HONOR

Conventional lithium-ion batteries typically consist of a lithium oxide cathode and a graphite anode. As the battery is discharged, lithium ions move from the anode to the cathode by traversing the electrolyte, which is usually made up of a polymer in Li-Pol batteries.

Simultaneously, the positively charged anode attracts negatively charged anions, which then chemically react with the anode, giving up electrons in the process. These liberated electrons can’t traverse the electrolyte and so take the path of the external circuit, powering electronic devices in the process. That’s chemistry 101.

Silicon-carbon (Si-C) batteries differ slightly from conventional lithium-ion ones in their choice of the anode, opting for a silicon anode instead of one made of graphite. Specifically, the anode here consists of a nanostructured silicon-carbon composite material.

So, what’s the catch? Well, a silicon anode can hold up to 10x as many lithium ions, essentially increasing the battery’s capacity by orders of magnitude.

Of course, it was this capacity of Si-C batteries to soak up to 10x as many lithium ions that had remained a huge bane for a long time: the anode would swell up and deform the entire battery. The solution: adding fracture-resistant carbon nanostructures to silicon.

Xiaomi, HONOR, and Tecno smartphones are all using silicon-carbon batteries

Many Chinese brands have started using silicon-carbon batteries in their smartphones lately, including Xiaomi, HONOR, and Tecno. And, these are some of the slimmest phones around:

  1. The HONOR Magic V3 measures just 9.2mm when folded and an unbelievable 4.35mm when unfurled.
  2. The HONOR Magic V5 goes a step further, spanning just 8.8mm when folded and an eye-popping 4.1mm when unfolded.
  3. The OPPO Find N5 spans just 4.21mm when unfolded.
  4. The Tecno Pova Slim 5G has a width of just 5.95mm.

For comparison, Apple’s iPhone Air is just a tad slimmer than the Tecno Pova Slim 5G, at 5.6mm thick. However, the Tecno phone has a 5,160mAh silicon-carbon battery vs. the iPhone Air’s 3,149mAh battery.

To put this into perspective, Apple’s iPhone Air is just 6 percent slimmer than the Tecno Pova Slim 5G, but bears a battery that is around 39 percent smaller!

Now, consider a scenario where Apple might have chosen to pair its iPhone Air with a ~5,000mAh silicon-carbon battery. Remember, the iPhone 17 Pro Max has a battery capacity of 5,088mAh. Wouldn’t that have constituted a recipe for instant success?

Of course, I can understand why Apple chose not to go with silicon-carbon batteries. Even with fracture-resistant carbon nanostructures, these batteries still expand by around 20 percent when fully charged.

This constant expansion and deflation takes a toll on the battery’s longevity, with substantial degradation taking place within 2 to 3 years.

Ultimately, Apple had a choice: either produce a functional and very capable ultra-slim iPhone whose battery capacity degraded a bit faster, or opt for a functionally handicapped phone that was all show and no substance.

We all know the choices that Apple ended up making. And, the iPhone Air’s tanking sales are a testament to its flawed decision-making process, at least in this instance.

Source:A Silicon-Carbon Battery Could Have Rescued The iPhone Air