Tecno Unveils Ultra-Thin Spark Slim Concept Phone with 5.75mm Profile and Large Battery

Tecno has revealed the Spark Slim concept phone at MWC 2025, showcasing an astonishing 5.75mm thickness that currently leads the industry. Although positioned as a concept piece, Tecno hints at plans to bring similar design elements to market later this year. The device enters a growing competition among manufacturers aiming to create ever-thinner smartphones ahead of anticipated launches like Apple's iPhone 17 Air.

The Spark Slim arrives in two variants: a 4G model and a Pova Slim 5G edition. Both versions are exceptionally slim, measuring 5.93mm and 5.95mm respectively, and each weighs approximately 156 grams. To achieve this ultra-thin profile, Tecno redesigned internal components, including a USB Type-C connector measuring just 0.45mm thick and a vapor chamber as thin as 0.3mm. Remarkably, the phone retains a substantial 5160mAh battery that manages to fit within a mere 4.04mm thickness.

Users will find a 6.78-inch curved AMOLED display offering a smooth 144Hz refresh rate and impressive 4500 nits of peak brightness. The rear panel is available in either stainless steel or ceramic finishes. Reviews from GSMArena note that while the stainless steel version offers a premium mirror-like appearance that quickly smudges, the ceramic option resists fingerprints better and maintains its looks over time. Tecno added artificial weight to prevent the device from feeling overly light and flimsy.

Engineered with rounded edges throughout, the phone incorporates an aerospace-grade fiberglass back cover just 0.36mm thick. The manufacturer employs a technology called Honeycomb Space Stacking to optimize internal space, though specific implementation details remain undisclosed.

Under the hood, the 4G Spark Slim operates on a Helio G200 processor, paired with 8GB of RAM and storage options of either 128GB or 256GB. The device runs Android 15 with Tecno's HiOS 15 interface. However, given the extreme thinness, potential heat buildup during intensive gaming sessions remains a concern.

A dual 50MP camera setup sits on the rear, accompanied by a distinctive Mood Light LED bar capable of displaying various lighting effects and animations for notifications. The sizable 5160mAh battery supports 45W fast charging, with the challenge of heat management during charging apparently difficult to solve. Additionally, the phone includes 10W reverse wired charging, enabling users to power other devices from the device itself.

One notable challenge presented by such an ultra-thin design is the difficulty of finding compatible protective cases. Despite the use of premium materials, the exceptionally slim profile raises questions about durability and potential bending, reminiscent of past issues with thin devices like the iPhone 6 Plus.

As this remains a concept model, official pricing has not yet been announced. The device is currently generating significant interest for its pioneering thinness combined with a large battery capacity.