Slim is in: How smartphones are getting thinner without sacrificing power

For years, smartphone manufacturers have been caught in a delicate balancing act – juggling battery life, performance, and design. Consumers want sleek, lightweight devices, but not at the expense of all-day battery life and top-notch performance.

The latest breakthrough in smartphone innovation aims to solve this dilemma with ultra-thin smartphones that house massive batteries. Wondering how? Read on.

The rise of ultra-thin phones

At MWC 2025, we had the chance to look at two standout slim phones – the Tecno Spark Slim and the Samsung Galaxy S25 Edge. The former stood out, even though it’s still at a concept stage.

The Spark Slim houses a 5,000mAh battery, which seems quite common, but here’s the kicker. This battery is housed in a body that is just 5.3mm thick – even thinner than a pen!

ALSO READ: Tecno Spark Slim is one of the world’s thinnest smartphones

In a conversation with Unboxed, Arijeet Talapatra, CEO of Tecno, emphasised how the new silicon carbon battery technology has made such a design possible.

“If you see a 5,000mAh battery with 5.3mm thickness, it’s crazy,” he said, highlighting how traditional battery limitations are being overcome with new material innovations.

Several brands like Samsung, Apple, Oppo and others are also exploring silicon carbon batteries and AI-driven power optimisation to ensure that future devices can offer extended battery life without compromising on design.

Samsung’s S25 Edge offers a slim look; however, the official battery capacity remains unknown. The speculated iPhone 17 Air is also said to have a slim form factor. If Apple incorporates silicon carbon tech to ensure the battery is long-lasting, it could be a smash hit product. The shift marks a major industry-wide push to balance aesthetics with usability.

The power of silicon carbon batteries

One of the biggest challenges in making ultra-thin smartphones has always been battery bulk. Traditional lithium-ion batteries have long dictated the thickness of a phone. However, the introduction of silicon carbon batteries is proving to be a game-changer.

ALSO READ: What are Silicon Carbon batteries, the tech that’s making batteries bigger and phones slimmer?

These batteries offer higher energy density in a smaller footprint, allowing manufacturers to pack more power into slimmer bodies. Recent phones like the OnePlus 13 and Vivo V50 also come with this tech, allowing them to have larger capacity batteries while maintaining a slim form factor.

With this innovation, brands can now reduce the size of battery components without sacrificing power output. This also results in better thermal efficiency, which reduces overheating concerns and enables faster charging speeds, an essential feature for power users.

Keeping cool: The challenge of heat dissipation

Even though silicon carbon batteries are more thermally efficient, a thinner body still means there’s less space for heat dissipation. This makes cooling systems crucial for maintaining device performance.

To combat this, brands are turning to advanced cooling solutions like vapour chambers, graphene layers, and AI-powered thermal management.

These innovations help regulate temperature, ensuring that smartphones can handle demanding tasks like gaming, video editing, and multitasking without overheating.

Why ultra-thin phones could be the future

While gaming smartphones and productivity-focused devices may continue to favour bulkier designs for performance reasons, the mainstream market is shifting towards ultra-thin, stylish, and lightweight devices.

The reasons are clear. Slim smartphones offer better portability – they are easier to carry and use with one hand. Plus, they tend to feel more premium as well.

As the industry continues to innovate, the race for thinner, more powerful smartphones is far from over. With silicon carbon batteries, AI-driven optimisations, advanced cooling systems, and premium materials, brands are ensuring that users no longer have to compromise between form and function.