Basalt fibers as sustainable alternatives to carbon fibers in structural and electrochemical energy storage: Opportunities and limitations

The growing demand for lightweight multifunctional materials has accelerated the integration of structural load-bearing capability with electrochemical energy storage. Carbon fibers remain the benchmark for structural batteries and supercapacitors because of their high strength, stiffness, and intrinsic electrical conductivity (10 3 –10 5 S m −1 ); however, energy-intensive production, high cost, and end-of-life challenges motivate sustainable alternatives. Basalt fibers provide competitive mechanical performance, thermal and chemical stability, flame resistance, electrical insulation, and potential cost advantages, although their low intrinsic conductivity restricts direct electrode functionality. Surface functionalization using carbonaceous coatings, graphene/carbon nanotube networks, conductive polymers, metal oxides, and MXenes can increase basalt-fiber conductivity to approximately 10 2 –10 3 S m −1 . This review critically evaluates when and where basalt fibers can replace or complement carbon fibers by comparing mechanical, electrical, electrochemical, thermal, economic, environmental, and technology-readiness characteristics. Particular attention is given to functionalization durability, failure mechanisms, coupled mechanical–electrochemical performance, manufacturing scalability, and life-cycle considerations. Hybrid carbon/basalt architectures emerge as a practical pathway by combining carbon-fiber conductivity and stiffness with basalt-fiber structural support, electrical insulation, thermal resistance, and sustainability potential. Future development requires scalable functionalization, standardized coupled testing, device-level validation, life-cycle and techno-economic assessment, and emerging approaches involving biomass-derived carbon coatings, solid-state structural batteries, and AI-assisted materials optimization.