It's been a week since the Samsung Galaxy S25 Edge launched. But even as the tech world moves on, and we witness the launch of the Nintendo Switch 2, and the build-up to WWDC 2025, it's still occupying space in my mind, and the minds of my colleagues, for being a competent but confusing device.
We like the Galaxy S25 Edge plenty, but all the same it feels like the iPhone 17 Air, expected later this year, could easily beat the S25 Edge as long as it does more than just be thin, or makes fewer sacrifices like pricing or camera performance in the name of slimming things down. But there's one thing both companies could have done to help, but that Samsung has not done, and that I expect Apple won't do either. And it's the crux of why I think Samsung and Apple should leave the slim phone idea to other companies.
Cutting edge design, but familiar internals
Batteries is the obvious area where thin phones run into limitations. Less internal space requires a sacrifice of battery size and capacity, and that's exactly what we saw in our own battery testing of the Galaxy S25 Edge, which found that the S25 Edge has a battery life between around three and four and a half hours shorter than other Galaxy S25 models. This wasn't inevitable though — Samsung just needed some new tech to help.
Brands like OnePlus and Honor have been launching phones with silicon-carbon battery tech — a new combination of materials for batteries that packs more power into a smaller area. This is ideal for a slim phone like the Galaxy S25 Edge, which needs a big battery to fuel its big 6.7-inch screen, but can't take the battery from the identically-sized Galaxy S25 Plus due to its reduced depth.
However, Samsung elected to stick with good old lithium batteries for the S25 Edge. Which meant it's ended up with a smaller capacity than the much smaller Galaxy S25, and resulted in the underwhelming battery life results I mention above.
If Samsung hasn't done it, Apple likely won't also
Optimistically, a smaller battery for the rumored iPhone 17 Air will perhaps be less of an issue than it is on the Galaxy S25 Edge. Apple's good at getting the most out of smaller batteries with its in-house hardware and software, as we can see on our best phone battery life guide with the iPhone 16 Pro Max. Apple's current top iPhone lasts slightly longer on the TG custom battery test than the Galaxy S25 Ultra, but while using a 6% smaller battery.
But the iPhone 17 Air would still presumably get more battery life if Apple elected to use silicon-carbon batteries. I don't have high hopes of Apple fulfilling my wish though, given how the company is normally slower than other brands to integrate new tech into its products. Just look at the iPhone Fold, or rather the current lack of one, compared to the seventh-generation foldables Samsung is expected to launch later this year. It really shows how patient Apple can be about fitting new tech to its phones.
So Apple's expected reluctance to address the slim phone battery life question, and Samsung's open focus on design over outright performance with the Galaxy S25 Edge, is why these are the wrong two companies to be pushing this phone format. I don't think the slim flagship phone's going to catch on until users can be certain they'll still get a day's use out of their new phone.
Silicon-carbon battery tech is the obvious way to fix this, and therefore Honor, OnePlus and other companies already experimenting with the technology should use this knowledge to show us how slim phones should be done.
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