Hard Carbon Microtubes Made from Renewable Cotton as High‐Performance Anode Material for Sodium‐Ion Batteries

TLDR

Sodium‑ion batteries are increasingly attractive for large‑scale energy storage because of abundant Na resources, yet the anode remains a major challenge. This work reports the fabrication of uniform hard carbon microtubes from natural cotton and their use as a high‑performance anode. The microtubes are produced by a single‑step carbonization of cotton fibers at controlled temperatures. Carbonization at 1300 °C yields hard carbon microtubes with a tubular structure that deliver a reversible capacity of 315 mAh g⁻¹ and excellent rate capability, demonstrating a new route to hard carbon anodes and advancing understanding of sodium storage.

Abstract

Sodium‐ion batteries (SIBs) have attracted more and more attention for scalable electrical energy storage due to the abundance and wide distribution of Na resources. However, the anode still remains a great challenge for the application of SIBs. Here the production of uniform hard carbon microtubes (HCTs) made from natural cotton through one simple carbonization process and their application as an anode are reported. The study shows that the electrochemical performance of the HCTs is seriously affected by the carbonization temperature due to the difference in their microstructure and heteroatomic content. The HCTs carbonized at 1300 °C deliver the highest reversible capacity of 315 mAh g −1 and good rate capability due to their unique tubular structure. This contribution not only provides a new approach for the preparation of hard carbon materials with unique tubular microstructure using natural inspiration, but it also deepens the fundamental understanding of the sodium storage mechanism.