Transforming Old T-Shirts: Cotton Waste Powers Future Supercapacitors in Minutes with Microwave Technology

While the world is trying to solve the problem of textile waste, researchers have found a way to turn cotton waste into something much more useful than floor rags. We're talking about creating high-quality carbon materials, which can become the basis for future energy storage devices. Instead of decomposing in landfills for years, old clothes now have the chance to end up inside your next electric vehicle or smartphone.

A microwave instead of a furnace: how to speed up production dozens of times

The traditional method of turning biomass into carbon is a long and energy-intensive process of firing in special furnaces, which usually lasts about an hour and a half. However, the new technology radically changes the rules of the game. Using microwave radiation in “traveling wave” mode allows you to reduce this cycle to a few minutes. This is not just a time saver; it's a true technological leap, making production significantly cheaper.

The main advantage of the microwave approach is the uniform and ultra-fast heating of the raw material throughout the volume. In a conventional furnace, heat is transferred gradually from the surface to the center, which often leads to material heterogeneity. Here, we achieve stable output quality using regular textile industry scraps as raw materials. This perfectly fits into the closed-loop economy concept, where waste becomes a resource.

Pore architecture: why structure matters

The resultant carbon becomes the basis for supercapacitor electrodes. These are devices that, unlike conventional batteries, can almost instantly accumulate and release large amounts of energy. But for them to work efficiently, the material must have a specific structure.

The new method allows creating a unique combination of small and large pores. Such a hierarchy works like a branched road network: large pores serve as “highways” for the rapid movement of electrolyte ions, while small ones provide a large surface area for charge accumulation. As a result, the devices maintain high efficiency even under extreme loads.

Impressive endurance

One of the weakest points of modern energy storage devices is their degradation. However, carbon materials from cotton demonstrate remarkable resilience. Tests showed that such electrodes retain more than 95% of their capacity even after 20,000 charge-discharge cycles. For comparison, a typical lithium-ion battery begins to noticeably “give up” already after 500–1000 cycles.

This makes the technology promising for use in electric transport, where the speed of energy recuperation during braking is important, as well as in portable electronics, which require fast charging. Essentially, we obtain a cheap, eco-friendly, and durable component that literally lies at our feet in the form of waste.

By the way, while on Earth they are trying to recycle waste in an environmentally friendly way, things aren't calm in space either — it was recently discovered how a solar strike on Mars almost stripped the planet of its remaining atmosphere.