Sustainable upcycling of ABS plastic waste into nanostructured carbon for lithium-ion battery applications

Acrylonitrile butadiene styrene (ABS), a high-performance thermoplastic widely used in electronics and 3D printing filaments, contributes significantly to the plastic waste problem due to its non-biodegradability. At the same time, the global push toward portable electronics and large-scale renewable energy storage systems has generated unprecedented demand for high-performance lithium-ion batteries (LIBs). We propose a way to convert ABS plastic waste directly from 3D printing scraps and failed prints into nanostructured carbon anodes for LIBs, valorizing a waste stream that is otherwise landfilled or downcycled. We systematically explored and compared the efficiency of our synthetic route, an acid-assisted route involving H₂SO₄ cross-linking prior to pyrolysis, with that of the conventional method. The addition of sulfonic groups (-SO₃H) to the polymer structure stabilized the structure during heat treatment and promoted partial graphitization and the creation of a disordered porous structure. As a result, the carbon yield via cross-linking reached 30.13%, which is 6 times higher than that yielded by bare ABS. Structural characterization confirmed an expanded interlayer spacing of 3.7 Å, the presence of nanoscale graphitic domains, and a defect-rich microstructure, which are characteristics favorable for Li⁺ intercalation. In terms of electrochemical performance, the anode demonstrated a reversible capacity of more than 300 mAh g^-1 in the first cycle, which was retained even after 100 cycles with a coulombic efficiency of 98%. It maintained excellent performance even at -15 °C. This work demonstrates that ABS plastic waste-one of the fastest-growing plastics in the 3D printing industry-can be directly converted into high-performance anode materials for lithium-ion batteries, offering a practical route for diverting this waste stream toward a valuable end use. A full assessment of the process's environmental footprint (chemical and energy inputs and wastewater generation) is needed before establishing its broader sustainability relative to the processes using conventional carbon sources.