Transforming renewable carbon fiber performance, economics, and sustainability via oriented crystallization design

Lignin-based carbon fiber offers a sustainable and cost-effective alternative to petroleum-derived products, yet research has failed to achieve commercially relevant performance. We demonstrated crystallite orientation enhancement as a new strategy to improve performance. Functionalized single-walled carbon nanotubes (F-SWCNTs) were introduced as a crystallization inducer, followed by external stress-guided structure adjustment and carbonization optimization. The resulting carbon fiber exhibited an increased crystallite orientation that substantially improved mechanical performance and electrical conductivity. Further analysis confirmed that the incorporation of F-SWCNTs significantly enhanced the structural integrity and crystallite orientation when tension application and carbonization temperature were co-optimized. The industrially relevant wet-spun lignin-based carbon fiber achieved a tensile strength of 2.04 GPa and an elastic modulus of 176 GPa, surpassing the automotive industry application standard. Techno-economic and life cycle analyses indicated substantial potential to reduce cost and environmental footprint. The study revealed critical design principles for high-quality materials and enabled a sustainable path for lightweight materials.