Waste to wealth: Turning everyday materials into tomorrow’s batteries

Faded, frayed and bound for the bin. Your old cotton T-shirt might not look like much, but it could have a surprising afterlife.

In a Deakin University lab, it’s being reborn as hard carbon – the key ingredient in a new generation of sustainable batteries.

Australia’s textile waste problem is immense, with around 300,000 tonnes of clothing either buried in landfills or dumped in developing countries every year.

At Deakin Institute for Frontier Materials, Associate Professor Nolene Byrne is working on a surprising answer to our fast fashion nightmare: turning old clothes into battery materials.

Byrne’s team is developing methods to convert waste biomass into high-performing hard carbon anodes for use in sodium-ion batteries – an emerging alternative to lithium-ion technology, which relies on scarce and expensive minerals.

While they are unlikely to replace lithium batteries in high-tech gadgets or electric vehicles, sodium-ion systems are well-suited to stationary energy storage, from home solar systems to large-scale renewable grids.

By replacing lithium with sodium and graphite with hard carbon made from discarded cotton, Byrne’s team is showing how waste can become the backbone of the renewable energy future.

Most modern clothing is made from blended fibres, such as cotton mixed with polyester or elastane, and a cocktail of dyes and finishes that are incredibly difficult to separate. When textiles are recycled, the processes used can result in the fibres becoming too short and weak to be spun into quality fabric.

As a result, less than one per cent of textiles globally are recycled into new clothing, with the rest shredded and downcycled into rags, mattress stuffing and insulation, or sent to landfill.

One established method for textile recycling involves using solvents to dissolve the material and regenerate it into new fibres, such as Lyocell. However, it is technically demanding, energy-intensive, and expensive.

At Deakin, Byrne’s PhD students have been refining a related process using ionic liquids to dissolve textiles for fibre-to-fibre recycling. But with a background in electrochemistry, Byrne knew there was another promising pathway for cotton waste: upcycling it into battery materials.

Cellulose, which gives plants and fibres their strength, is the most abundant organic polymer on Earth. When heated in the absence of oxygen, it breaks down to leave a lightweight, conductive carbon structure which is an ideal material for battery anodes.

Unlike most of the other routes for recycling textile waste, the process creates a higher-value material.

‘If you take the textile waste and you carbonise it into a hard carbon that is an upcycling solution,’ Byrne says.

The same principles that make cotton an effective feedstock for hard carbon can also be applied to another overlooked resource: biosolids from wastewater treatment.

Byrne’s group has been working with Barwon Water in Geelong to explore how this resource could be transformed into battery materials. The work, still in its early stages, has already been recognised with the Australian Water Association’s Victorian R&D Excellence Award.

As part of Barwon Water’s broader circular economy strategy, biosolids, along with food and garden organics such as lawn clippings, are being converted into biochar – a carbon-rich material traditionally used to improve soil health and lock carbon into the ground.

This research is supported by Deakin’s Recycling and Clean Energy Commercialisation Hub (REACH), which facilitates the development of greener supply chains and collaborates with industry partners to pioneer a sustainable circular economy.

A feasibility study will determine whether that biochar can be further refined into a hard carbon suitable for use in sodium-ion batteries.

‘The challenge in any reuse of waste usually lies in the diversity of the waste stream,’ Byrne says.

‘Definitely one challenge that we have with the Barwon Water project is that there's lots of wonderful things inside that come out of the waste treatment plant, and some of those things we'll have to remove.’

If successful, the project promises to close another loop by transforming municipal waste into a local clean-energy solution, reinforcing Deakin Institute for Frontier Material’s belief that the materials we discard, from T-shirts to sewage, can become the raw ingredients of a sustainable future.