Electric car batteries rely on critical materials such as lithium and cobalt, whose extraction is costly and has a significant environmental impact. The search for sustainable alternatives is vital for the future of batteries.
One of the most promising options is sulfur-based batteries, capable of offering greater storage capacity and lower cost.
The discovery in Spain: activated carbon from sludge
Researchers from the Chemical Institute for Energy and the Environment (IQUEMA) at the University of Córdoba (Spain) have developed a method to produce activated carbon from sewage sludge, an abundant and difficult-to-manage waste.
In Spain, around one million dry tons of this waste are generated each year, making this innovation a double solution: valorizing urban waste and creating a strategic resource for the energy transition.
The system was tested at the Villaviciosa wastewater treatment plant, managed by EMPROACSA, in the province of Córdoba. “It is a great advance that we achieved from a waste we considered problematic,” the researchers noted.
The process: from sludge to conductive material
The project is based on a biological technology called “Biodiscs”, already used in treatment plants. The procedure consists of:
- Drying the sludge.
- Adding a chemical agent (potassium hydroxide) that modifies the structure and increases porosity.
- Thermochemical pyrolysis treatment in an oven at 800 °C, which transforms the organic matter into carbon.
- Mixing the carbon with sulfur in a ball mill, generating a material ready to be incorporated into battery electrodes.
This activated carbon functions as a conductive matrix, solving one of the main problems of lithium-sulfur batteries: the low conductivity of sulfur in the cathode.
Advantages of lithium-sulfur batteries
Research from the Department of Inorganic Chemistry and Chemical Engineering at the University of Córdoba highlights that these batteries can:
- Triple the storage capacity compared to conventional lithium-ion batteries.
- Be easier to recycle, reducing costs and waste.
- Use more accessible and less polluting materials.
The use of activated carbon obtained from sewage sludge allows for cheaper production and progress towards a circular economy model in the energy sector.
Challenges ahead for a future with sustainable batteries
Despite their advantages, lithium-sulfur batteries face technical challenges:
- Cathode degradation after many charge and discharge cycles.
- Long-term stability still insufficient.
- Need to optimize electrodes to improve performance and durability.
Therefore, researchers emphasize that there is still work to be done before these batteries can massively replace lithium-ion batteries in electric cars.
Waste as a strategic resource
The Córdoba project demonstrates that urban waste can become key resources for the energy transition. The valorization of sewage sludge opens new lines of research and offers a sustainable alternative for energy storage.
In a context of increasing demand for electric vehicles, innovations like this are essential to reduce dependence on critical materials and move towards cleaner and more circular mobility.
