Hard carbon micro-nano tubes derived from kapok fiber as anode materials for sodium-ion batteries and the sodium-ion storage mechanism

• Published in: Chemical communications (Cambridge, England) Vol. 56; no. 5; pp. 778 - 781
• Main Authors: Yu, Zhuo-Er, Lyu, Yingchun, Wang, Yeting, Xu, Shuyin, Cheng, Hongyu, Mu, Xiaoyang, Chu, Jiaqi, Chen, Riming, Liu, Yang, Guo, Bingkun
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 16.01.2020
• Subjects: Anodes; Carbon; Electrode materials; Electron paramagnetic resonance; Ion storage; Rechargeable batteries; Sodium; Sodium-ion batteries; Storage batteries; Thermogravimetric analysis
• DOI: 10.1039/c9cc08221b
• ISSN: 1359-7345

Hard carbon materials are considered as the most promising anode for sodium-ion batteries (SIBs). However, the high cost and poor rate performance hinder their application in SIBs. Moreover, the controversial mechanism of Na-ion storage restricts the improvement of hard carbon anodes. Herein, hard carbon micro-nano tubes (HCMNTs) from low-cost biomass kapok fibers are prepared as a promising anode for SIBs. Benefitting from the micro-nano structure, which offers low surface area and short Na + diffusion path, 1400HCMNT possesses a good initial Coulombic efficiency of 80%, a high reversible capacity of 290 mA h g −1 , and an excellent rate capacity. Furthermore, electron paramagnetic resonance and thermogravimetric analysis were applied to investigate the Na-ion storage mechanism in the HCMNTs. Sodium is stored in the hard carbon in an ionic state in the slope region and as quasi-liquid metallic sodium clusters in the low-voltage plateau. Sodium is stored in hard carbon in an ionic state in the slope region and in a quasi-liquid metallic sodium cluster state in the low-voltage plateau.