We recently got a closer look at the Tecno Spark Slim through a showcase video by PhoneBuff, and it’s clear that Tecno is aiming squarely at the thin-and-light smartphone market. It’s an arena currently dominated by heavyweights like Samsung’s Galaxy S25 Edge and Apple’s iPhone Air, where design, portability, and efficiency take priority.
But as we’ll see, Tecno may have found a way to outmanoeuvre both giants in one crucial area: Battery capacity.
A 5,160mAh battery in a 5.95mm body!
Tecno pulled off something surprising with the Spark Slim! It managed to fit a 5,160mAh battery into a phone that measures 5.95mm thin and weighs just 158g. To put that into perspective, the Galaxy S25 Edge has a 3,900mAh battery in a 5.8mm, 163g frame, while the iPhone Air packs 3,149mAh in a 5.6mm, 165g frame.
That means the Tecno Slim offers 32% more battery capacity than the S25 Edge while only being 2.5% thicker, and 64% more battery capacity than the iPhone Air.
In fact, the Slim’s battery is even larger than the 5,000 mAh pack inside Samsung’s heavyweight Galaxy S25 Ultra, showing just how ambitious Tecno’s engineering is. While Tecno hasn’t confirmed the exact battery type, the capacity-to-size ratio hints that it could be using a silicon-carbon solution.
The difference in thickness between the Tecno Spark Slim and the Samsung Galaxy S25 Edge might be negligible at 0.15mm, especially given Tecno’s curved edges that make it feel slimmer in the hand.
But the jump from the Apple iPhone Air to the Tecno Spark Slim might be noticeable. However, given how much longer you can use your Tecno Spark Slim, it’s a trade-off most people would take any day.
Battery Life: Tecno Outlasts the Competition
The real test of any battery is, of course, screen-on time. According to PhoneBuff’s showcase, the Tecno Spark Slim delivered an impressive 11 hours 47 minutes, while the Galaxy S25 Edge managed 9 hours 59 minutes. That’s about an 18% increase in screen-on time, which roughly aligns with the 32% bigger battery.
Qualcomm’s Snapdragon 8 Elite deserves credit here for efficiency, pulling respectable numbers out of a smaller pack. But Tecno’s result is arguably more impressive, since its Dimensity 6400 (or possibly Helio G200 in some regions) is a mid-range chip that still managed to keep pace in terms of efficiency.
Even more striking: the Tecno Spark Slim nearly matches the Galaxy S25 Ultra, which has a 5,000mAh battery and recorded 11 hours 50 minutes in the same test. That puts the Spark Slim shoulder-to-shoulder with a flagship device that’s almost twice as thick and heavy.
As for the iPhone Air, we don’t have official screen-on time numbers yet. But given its 3,149mAh battery, it’s unlikely to outlast the Tecno Spark Slim. Even with Apple‘s optimisations in iOS and hardware, Tecno’s sheer battery advantage gives it the upper hand. As the automotive saying goes, “there is no replacement for displacement.”
And if the iPhone Air somehow does outperform Tecno here, well… hell might freeze over.
Even with a massive battery, it’s the lightest
At 158g, the Tecno Spark Slim undercuts both the Galaxy S25 Edge (163g) and iPhone Air (165g), an impressive feat considering its 5,160 mAh battery. That’s thanks to a smart material choice: fibreglass for the back panel, paired with what’s likely an aluminium frame.
In contrast, both Samsung and Apple use titanium frames, which are stronger but heavier. That decision does contribute to their advantage in terms of durability at this thickness. But Tecno’s focus is on keeping the Spark Slim genuinely featherlight, even if that means a lower structural strength.
As for thickness, the Spark Slim measures 5.95 mm, which on paper makes it slightly thicker than the Galaxy S25 Edge (5.8 mm) and even thicker than the iPhone Air (5.6 mm). Thickness, including the camera bump, is another story. Samsung’s Edge jumps up to 8.45 mm once you include it, while Tecno and Apple’s exact numbers are still unconfirmed.
That means Tecno doesn’t quite have the bragging rights of being “the thinnest,” as that title still goes to the Oppo R5 at 4.85 mm thick. So it cleverly markets itself as the thinnest curved screen smartphone, sidestepping the technicality.
Rest of the Specs
Beyond the battery, weight, and thickness story, the Tecno Slim keeps things simple in other areas.
On the back, it features a 50MP main camera. While PhoneBuff’s video and our own hands-on experience with a concept unit show a secondary cutout next to it, Tecno’s own website only lists a single camera, leaving it unclear whether the second unit is functional or decorative.
In practice, that puts the Spark Slim on a similar footing to the iPhone Air, which also relies on a single main sensor, though still behind the Galaxy S25 Edge, which comes with a more versatile multi-camera setup that includes an ultra-wide-angle lens.
That said, purely from observation, the camera bump on the Tecno Spark Slim looks to be flat and even, preventing the phone from rocking when placed down. This is not the case with the other two phones. Samsung’s Galaxy S25 Edge has its camera bump at the top, left side of the body, which causes the phone to rock when placed down.
And while the iPhone Air has a similar camera bar to the Tecno Spark Slim, its camera protrudes out of the bar, lifting the left side of the phone, causing it to rock when placed down. Now I don’t know if this is a deal breaker, but it’s something I noticed right away since my Galaxy Note9 has a flat back and doesn’t rock on a table.
The Spark Slim features a 6.78-inch curved AMOLED panel with a 1.5K resolution and 144Hz refresh rate, protected by Corning Gorilla Glass 7i. We hope it’s an LTPO panel. Tecno claims a peak brightness of 4,500nits, which is impressive given the cooling required.
PhoneBuff’s showcase unit was a 5G model and featured the MediaTek Dimensity 6400, but Tecno’s global website lists the MediaTek Helio G200, with no mention of a MediaTek unit. It’s possible that different regions will receive different processors, or that Tecno’s site hasn’t been updated. Either way, both chips fall short of Qualcomm’s Snapdragon 8 Elite and Apple’s A19 Pro in sheer performance.
A nice bonus here is dual speakers. What’s more surprising is that Tecno managed to get these speakers certified for Dolby Atmos! That’s way more than what the iPhone Air’s mono earpiece speaker can manage.
The Spark Slim supports 45W fast charging, easily outpacing the Galaxy S25 Edge’s 25W and the iPhone Air’s ~20W.
On the software front is where Tecno falls apart completely, promising just 1 OS upgrade and 2 years of security patches for the Spark Slim, according to PhoneBuff.
In stark contrast, Samsung is offering 7 years of software and security patches for the Galaxy S25 Edge, while Apple, as usual, doesn’t make formal promises but tends to support devices for five years or more. That means the Slim can’t match the long-term value of its rivals, so its price must be a lot more affordable.
Tecno, please bring the Spark Slim to Malaysia
The Tecno Spark Slim might just be the first thin and light smartphone to deliver regular-sized phone battery life. That alone makes it a fascinating entrant in a space where endurance has always been the weak link.
Of course, the Spark Slim isn’t pretending to be a flagship. Its mid-range processor can’t touch the Galaxy S25 Edge or iPhone Air in raw power, nor can its single-camera setup compete with the versatility of Samsung’s optics. But for day-to-day use, like social apps, media, and light gaming, Tecno may have found the sweet spot if the price is right.
Now the big question is whether Tecno will bring the Spark Slim to Malaysia. If it does, the contest here becomes a two-way battle between Tecno and Apple, since Samsung’s Galaxy S25 Edge isn’t officially sold locally.
