Ryan Haines / Android Authority
Thin phones are the hottest thing in flagships right now, and it’s easy to see why. They try to fit the best of the Android or iOS experience into a lighter, easier-to-hold body, pushing the limits of engineering along the way. Only, in the case of the Samsung Galaxy S25 Edge and iPhone Air, there are quite a few limits to be found — especially when it comes to battery life. Now, TECNO wants to prove that there are ways around those limits. It has introduced its own ultra-slim challenger, the TECNO Slim, with an eye on the thin phone crown.
But can it truly compete with Samsung’s flagship? Let’s dig into its battery, design, and AI features to find out.
Power comes first
Ryan Haines / Android Authority
Right now, there’s no bigger challenge for slim phones than figuring out the perfect battery and charging setup. Samsung, for example, stuck its Galaxy S25 Edge with the smallest battery in its flagship lineup, a mere 3,900mAh, despite having the second largest display behind only the Galaxy S25 Ultra. As you might imagine, the Edge’s battery performance lags, too, falling behind other Galaxy S25 models with its limited space for cooling technology and power-hungry processor.
The new TECNO Slim, on the other hand, makes the most of its battery capacity with an impressive 5,160mAh cell — yes, more than 1,000mAh larger than its ultra-thin competition. It’s a level of space management that you probably wouldn’t have thought possible while holding something like the Galaxy S25 Edge, but TECNO credits its honeycomb stacking technology with helping to minimize the space that components need, allowing for a larger battery.
That beefed-up battery doesn’t come with the usual compromise — stripped-back cooling technology — either. Instead, TECNO managed to fit a 0.3mm vapor chamber with highly conductive graphite to push heat out almost as quickly as it’s generated. All of this combines into one light, thin phone that lets you game and stream for longer.
Ryan Haines / Android Authority
Of course, listing battery specs on paper doesn’t mean much — how a phone performs really matters. On that front, the TECNO Slim puts up impressive numbers compared to the Samsung Galaxy S25 Edge, beating it across almost all categories in our standard battery drain test that compares how many minutes a phone can repeat a certain task during a full drain of its battery on the X-axis. TECNO’s razor-thin phone comfortably tops the Edge in everything, from a simulated zoom meeting to snapping away with the camera and recording 4K videos.
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