Researchers from Hunan University and Changsha University of Science and Technology have demonstrated a superior sodium-ion anode material from phosphorus-doped carbon nanofibers (P-CNFs) with an inter-connected structure.

The P-CNFs exhibit higher interlayer spacing of graphite and lower BET specific surface area compared to the pristine CNFs. The P-CNFs as an anode material for sodium-ion batteries (SIBs) present a high reversible capacity 278 mA h g⁻¹ at 0.2 A g⁻¹ and a superior initial Coulomb efficiency (ICE) of 78.86%.

Moreover, the reversible capacity of P-CNFs can be stably maintained near the initial capacity after 5000 cycles at 1 A g⁻¹, showing exceptional structural stability and cycling durability.

A paper on their work is published in Journal of Power Sources.

Zou et al.

The team also investigated the sodium storage mechanism of P-CNFs using in-situ Raman and ex-situ XRD analysis to understand the exceptional structural stability and Na⁺ adsorption capacity of P-CNFs.

In this study, we have presented, for the first time, the synthesis of phosphorus-doped carbon nanofibers (P-CNFs) featuring unique interconnected network structures through cross-linking induced by phosphoric acid impregnation. This innovative method not only achieves successful phosphorus atom doping within the carbon fiber but also significantly influences the pyrolytic behavior of the nanofibers during carbonization, thereby effectively modifying the lapping morphology and pore structure of the resulting CNFs.

Firstly, PAN/Lignin-derived CNFs with network structure were successfully prepared by electrostatic spinning method using lignin and PAN as carbon sources. The P-CNFs with unique inter-connected structure were obtained by doping their pre-oxidized nanofibers using a phosphoric acid impregnation method, followed by the carbonization process. The P-CNFs exhibited superior electrochemical performance at 0.2, 1, and 5 A g⁻¹, with reversible capacities of 278, 220, and 202 mA h g⁻¹, respectively, when used as anode material for SIBs.

In addition, the specific surface area of P-CNFs was significantly reduced, which resulted in less solid electrolyte interface (SEI) formation and facilitated the improvement of the ICE. Hence, an anode material for SIBs with excellent reversible capacity, ICE and good rate capability was developed in this study.

—Zou et al.

Resources

• Jialing Zou, Xinnan Xie, Jianxiao Yang, Bingjie Wen, Jun Li, Ji Qin (2024) “A superior sodium-ion anode material from PAN/Lignin-derived carbon nanofibers with inter-connected structure prepared through phosphoric acid induced cross-linking,” Journal of Power Sources, Volume 593, doi: 10.1016/j.jpowsour.2023.233994.