Researchers have developed a new method to transform two major waste streams, discarded mobile phone batteries and industrial lignin, into a promising material for next-generation sodium-ion batteries. The study demonstrates how waste recycling can simultaneously reduce environmental pollution and support the transition to sustainable energy storage technologies.
Mobile phone batteries are replaced frequently, creating large quantities of electronic waste that contain valuable metals but also pose environmental risks if improperly discarded. At the same time, lignin, a natural polymer generated in huge volumes by the paper and biofuel industries, is often burned or disposed of despite its chemical potential. Scientists in the new study sought to address both problems by combining these wastes into a functional electrode material.
Using a hydrothermal synthesis process, the team extracted nickel and cobalt compounds from spent batteries and combined them with carbon derived from lignin. The resulting composite material, composed of nickel cobalt sulfides coated in lignin-derived carbon, showed strong electrochemical performance when tested as an anode in sodium-ion batteries.
"Sodium-ion batteries are attractive because sodium is abundant, low cost, and environmentally friendly," the researchers explained. "However, the development of efficient electrode materials remains a major challenge. Our work shows that waste resources can provide a solution."
The composite exhibited an initial discharge capacity exceeding 1,000 milliampere hours per gram and maintained strong performance during repeated charging cycles. Even at high current densities, the material retained notable capacity, demonstrating its ability to support rapid charge and discharge processes.
The improved performance is attributed to the material's unique structure. The lignin-derived carbon layer enhances electrical conductivity and stabilizes the electrode during cycling, while the metal sulfide components provide abundant reaction sites for sodium storage. Together, these features enable efficient ion transport and help maintain structural integrity over time.
According to the research team, the findings highlight a broader concept in sustainable materials science. "We wanted to move beyond traditional recycling and demonstrate true high-value reuse of waste," the authors noted. "By converting discarded batteries and industrial lignin into advanced energy materials, we can reduce costs, conserve resources, and support cleaner technologies."
Beyond laboratory performance, the study suggests that the approach could help lower manufacturing costs for sodium-ion batteries and increase their commercial viability. Because both feedstocks are widely available industrial wastes, the process may offer a scalable pathway toward greener battery production.
Sodium-ion batteries are considered promising alternatives to lithium-ion systems for applications such as grid storage, electric vehicles, and portable electronics. As demand for sustainable energy solutions grows, materials that combine low cost with strong performance will be essential.
The researchers believe their strategy provides a new framework for circular economy innovation. "Our work demonstrates that waste materials are not just a disposal challenge but a valuable resource," they concluded. "Integrating waste recycling with energy technology design could play an important role in building more sustainable power systems."
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Journal reference: Dun C, Zhao Y, Zhang P, Lv H, Liu Y, et al. 2026. Synergistic conversion of spent mobile phone batteries and industrial lignin into the NiCo2S4/Co9S8@LC composite with enhanced sodium storage performance. Biochar X 2: e007 doi: 10.48130/bchax-0026-0005
https://www.maxapress.com/article/doi/10.48130/bchax-0026-0005
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About the Journal:
Biochar X (e-ISSN: 3070-1686) is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.
