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. Well-rounded performance across all categories is everything you could ask for when getting sustained usage out of your super-thin phone. Besides, with more than an extra 1,000mAh at your disposal, you’ll be able to take the TECNO Slim on the go for much longer before you need a charger. TECNO's battery towers over the Galaxy S25 Edge... and its charging does, too. And, when you do finally kick the 5,160mAh battery, TECNO has another trick up its sleeve to flex its no-compromise muscle. The TECNO Slim supports 45W wired charging, as well as both reverse and bypass charging for added flexibility. Oh, and there’s a full-speed charger in the box, something Samsung hasn’t offered for several years. Compare that to Samsung’s 25W wired charging — the same as it offers on its smallest Galaxy S25 — and it’s not hard to see where the TECNO slim comes out a winner. While you might think that the Galaxy S25 Edge has an advantage in filling its smaller 3,900mAh cell, you’d actually be wrong once again. TECNO’s Slim fills in just under 55 minutes with a compatible charger, compared to just over an hour with the Galaxy S25 Edge. It’s a difference of minutes, but that could go a long way between missing your morning commute and being the first one in the office. Redefining slimness Ryan Haines / Android Authority Not only does the TECNO Slim last longer than the Galaxy S25 Edge, but it takes bolder design swings, too. Where Samsung’s super-skinny flagship looks a bit like a Galaxy S25 that you squeezed so tight its third camera fell off, the TECNO Slim sports a curved, futuristic design that you really don’t want to — or need to — put down. The secret to TECNO’s impressively comfortable design starts with its curves. Although waterfall edges have largely gone the way of wired headphones and removable batteries, the Slim features curves on both the front and back that lead gently to a glossy, color-matched frame. That frame is thin enough to make the entire Slim feel, well, even slimmer, yet the glossy frame doesn’t feel slippery in the hand. A quad-curved design makes the TECNO Slim feel even slimmer in your hand. Perhaps the most eye-catching part of the TECNO Slim’s display comes when you flip it over and are greeted with its light-up Mood Light interface. It loops around the nearly edge-to-edge camera bump, helping the 50MP primary sensor to stand out against the aerospace-grade fiberglass back panel. The Mood Light takes on a simple but essential role, adding a visual cue to everything from your ringtones to notifications and charging indicators for a bit more fun throughout the day. And, when you just want a little brightness, you can manually toggle the Mood Light for a little dance party. Ryan Haines / Android Authority TECNO didn’t forget about the Slim’s display, either, picking up a sizable 6.78-inch panel that’s just a little bit bigger than the Galaxy S25 Edge. The Slim’s 144Hz refresh rate and 4,500 nits of peak brightness push it even further ahead, and make games and videos look crystal clear. Compare that to the industrial, rectangular Galaxy S25 Edge, and there’s no question which device is more interesting. Samsung’s sharp, flat edges are anything but comfortable to hold for long stretches, and its thick, corner-mounted camera bar doesn’t sit nicely on a surface, no matter how you lay it down. It’s a classic Samsung design, just maybe not a very exciting one. Practical AI vs premium overload Ryan Haines / Android Authority Then, there’s the powerful world of AI — something that’s come to define flagships, whether they’re ultra-thin or not. Right now, there’s no escaping the fact that Samsung has a pretty rich slate of features, encompassing everything from the Now Brief to Drawing Assist to Audio Eraser. In fact, it seems like Galaxy AI reaches into every corner of the Galaxy S25 Edge, whether you need it there or not. The TECNO Slim, on the other hand, takes a small but mighty approach to AI — it grabs the features you want, but skips the tools you might not actually need every day. TECNO made sure to support Google’s Circle to Search, a helpful Live Translation feature, and an AI Eraser to help clean up unwanted people and objects from your sharp 50MP images. TECNO's less-is-more approach to AI means more time spent with features you actually need. Could you decide that you miss some of Samsung’s more advanced features by grabbing the TECNO Slim? Sure, but you’ll probably find that you actually use what’s there more regularly. AI Eraser, which is much like Google’s Magic Eraser, is an easy go-to for clearing out the clutter of so much everyday photography, making it much easier to ask the Ella AI assistant to share. Ella could share your original cluttered images, too, but it’s more fun to have them nice and cleaned up. And fear not, the TECNO Slim supports its own AI assistant, Ella, for all of the real-time questions you might want to ask about the world around you — further cementing TECNO’s less is more approach to simple, useful AI. In an ultra-thin world, the TECNO Slim stands tall Ryan Haines / Android Authority Put up against flagship giants like the Galaxy S25 Edge, the new TECNO Slim stands out in several ways. It takes the opposite approach to Samsung on almost all fronts, picking up a bigger battery, a more eye-catching design, and a streamlined approach to AI features that’s more practical for everyday life. The Slim is an excellent demonstration of what an ultra-thin smartphone can do when it skips common compromises and focuses on making the most of its value.