Flexible 3D self-interwoven nanofiber organic cathodes with interconnected multiscale micro/nanopores for enhanced lithium/sodium storage performance

Abstract

Although organic electrode materials have been considered promising alternatives to traditional inorganic electrode materials for lithium/sodium-ion batteries due to their flexible structural design, derivation from sustainable resources, and environmental friendliness, their development is still in its infancy because of poor electrical conductivity, solubility in organic electrolytes, and sluggish reaction kinetics. Herein, a novel flexible 3D self-interwoven multicarbonyl naphthalene-based polyimide (NTBP)/nitrogen-doped carbon (NC)/acidified carbon nanotubes (HCNT) (NTBP/NC/HCNT) composite fibrous membrane is prepared through electrospinning and thermal treatment techniques for applications in lithium/sodium-ion batteries (LIBs/SIBs). The NTBP/NC/HCNT nanofiber membrane is composed of interlaced nanofibers with multiscale micro/nanoporous conductive architectures. The designed architectures of NTBP/NC/HCNT enhance conductivity and provide a stable diffusion path for Li⁺/Na⁺, thereby facilitating rapid electronic/ionic transport and extremely fast reaction dynamics (Li⁺/Na⁺ diffusion coefficients ∼ 10⁻⁹ cm² S⁻¹). Consequently, the flexible NTBP/NC/HCNT cathode provides high reversible capacities of 146 mA h g⁻¹ and 168.5 mA h g⁻¹, achieving an unprecedented rate capability of 71 mA h g⁻¹ at 5000 mA g⁻¹ for LIBs and 84 mA h g⁻¹ at 5000 mA g⁻¹ for SIBs. Additionally, the flexible NTBP/NC/HCNT cathode also demonstrates superior cycling stability, maintaining over 99 % of its capacity after 500 cycles at a current density of 200 mA g⁻¹ for both LIBs and SIBs. This work offers a novel architectural design strategy for flexible composite organic cathodes to achieve excellent electrochemical performance in next-generation renewable energy storage devices.