Abstract Herein, a salt-assisted hydrothermal carbonization (HTC) strategy is applied to fabricate low-surface-area carbon microspheres (as low as 5.5 m2 g−1) for sodium ion batteries (SIBs) by using water containing eutectic salt melt (e.g. NaCl) and sugar (e.g. glucose) as reaction media. The small amount of salt increases the carbon conversion efficiency from 15.0 to 58.3%, and microsphere size from the nanoscale to the microscale. Meanwhile, the specific surface area of carbon microsphere is minimized and the microstructure is optimized. Ex-situ X-ray diffraction (XRD) and kinetic analysis revealed that the narrower lateral width of pseudographitic domains and lower micropore volume are the key factors to promote sodium storage ability and Na ion diffusion. The carbon microsphere anode delivers a capacity of 350 mAh g−1 with 73.0% from the low potential (0–0.2 V) at 100 mA g−1, a high initial Coulombic efficiency (ICE) of 86.1% (excluding conductive carbon black), and an excellent rate capability with capacity of 261 mAh g−1 even at 500 mA g−1. This research highlights a salt-assisted HTC method to synthesize low-surface-area carbon microspheres with superior ICE and energy/power density.

中文翻译：

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具有优异低电位容量的盐和糖衍生的高功率碳微球阳极

摘要 本文采用盐辅助水热碳化 (HTC) 策略，通过使用含有共晶盐熔体的水（例如，水）制备钠离子电池（SIBs）的低表面积碳微球（低至 5.5 m2 g-1）。 NaCl）和糖（例如葡萄糖）作为反应介质。少量的盐将碳转化效率从 15.0% 提高到 58.3%，使微球尺寸从纳米级增加到微米级。同时，最小化碳微球的比表面积，优化微观结构。异位 X 射线衍射 (XRD) 和动力学分析表明，拟石墨畴的横向宽度较窄和微孔体积较小是促进钠储存能力和钠离子扩散的关键因素。碳微球阳极提供 350 mAh g-1 的容量和 73。在 100 mA g-1 时从低电位 (0–0.2 V) 降低 0%，86.1% 的高初始库仑效率 (ICE)（不包括导电炭黑），以及具有 261 mAh g-1 容量的优异倍率性能即使在 500 mA g-1。这项研究重点介绍了一种盐辅助 HTC 方法来合成具有优异 ICE 和能量/功率密度的低表面积碳微球。