A team of researchers from the Department of Materials Science and NanoEngineering at Rice University jointly with their colleagues from Baylor University and the Indian Institute of Science Education and Research Thiruvananthapuram have presented a promising solution that could define the future of energy storage systems. The researchers have proposed using waste produced by the oil-and-gas industry in order to create carbon materials of unusual shapes: microscopic cones and disks with a pure graphite structure. These structures were obtained via scalable pyrolysis, i.e., oxygen-free decomposition of hydrocarbons at high temperatures. The study was funded by Omega Power and India’s Ministry of Science and Technology.
Instead of changing the chemical composition of carbon, the scientists changed its shape at the nanostructure level. They found that the new curved shapes are much better suited to reactions with sodium and potassium ions, which are not only bigger than lithium ones but also cheaper and more common. While these ions cannot fit in conventional graphite, they can freely enter the material in the new, more spacious cone and disc structures, exiting without the need for complex chemical changes.
These materials showed impressive results in laboratory conditions, holding about 230 mAh/g of charge with sodium ions and continuing to operate at 151 mAh/g even after 2,000 fast-charge cycles. In potassium-ion batteries, the efficiency was slightly lower.
Using state-of-the-art imaging techniques, including cryo-electron microscopy and solid-state nuclear magnetic resonance, the researchers confirmed that ions pass in and out of the carbon structure without being destroyed. Meanwhile, the material retains its shape and stability even after multiple charge and discharge cycles.
This discovery paves the way for cheaper, more reliable and more environmentally-friendly batteries, especially amid growing lithium shortages and rising costs. The possibility of recycling industrial waste into a valuable material makes this technology even more appealing.
