Low‐Temperature Growth of Hard Carbon with Graphite Crystal for Sodium‐Ion Storage with High Initial Coulombic Efficiency: A General Method,Advanced Energy Materials

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Low‐Temperature Growth of Hard Carbon with Graphite Crystal for Sodium‐Ion Storage with High Initial Coulombic Efficiency: A General Method
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2019-01-28 , DOI: 10.1002/aenm.201803648
Xun Zhao ₁ , Yuan Ding ₁ , Qi Xu ₁ , Xiao Yu ₁ , Yong Liu ₁ , Hui Shen ₂

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Practical application of hard carbon materials in sodium‐ion batteries (SIBs) is largely limited by their low initial coulombic efficiency (ICE), which may be improved by increasing the graphitization degree. However, biomass‐derived hard carbon is usually nongraphitizable and extremely difficult to graphitize by direct heating even at 3000 °C. Herein, a general strategy is reported for fabricating hard carbon materials with graphite crystals at 1300 °C promoted by external graphite that serves as a crystal template for the growth of graphite crystals. The graphite crystals enable the contacted pseudographitic domains with a high‐level ordered structure, large domain size, and low defects, leading to an enhanced ICE. The obtained hard carbon materials with graphite crystals, using the carbonized eggshell membranes, and sucrose‐derived microsphere as precursors, achieve very high ICE of 89% and 91% with reversible capacity of 310 and 301 mA h g⁻¹, respectively. Therefore, using external graphite to promote high‐level ordering pseudographitic domains at low temperature is quite useful to improve ICE for SIB applications.

中文翻译：

一种具有较高初始库仑效率的，用于碳酸钠离子存储的石墨晶体在低温下生长硬质碳的通用方法

硬碳材料在钠离子电池（SIB）中的实际应用在很大程度上受到其初始库伦效率（ICE）较低的限制，这可以通过提高石墨化程度来改善。然而，源自生物质的硬碳通常是不可石墨化的，并且即使在3000°C下也无法通过直接加热进行石墨化。本文中，报道了一种一般策略，该方法用于制造由外部石墨促进的，在1300℃下具有石墨晶体的硬碳材料，该外部石墨用作用于石墨晶体生长的晶体模板。石墨晶体使接触的伪石墨畴具有高阶有序结构，大畴尺寸和低缺陷，从而增强了ICE。使用碳化的蛋壳膜，获得具有石墨晶体的硬碳材料，^-1。因此，使用外部石墨在低温下促进高阶有序的伪石墨畴对于改善SIB应用的ICE非常有用。

更新日期：2019-01-28

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