关于硬碳微观结构对钠离子扩散到闭孔中的影响的新见解,Chinese Chemical Letters

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关于硬碳微观结构对钠离子扩散到闭孔中的影响的新见解
Chinese Chemical Letters ( IF 9.4 ) Pub Date : 2023-11-03 , DOI: 10.1016/j.cclet.2023.109266
Mingxin Song , Lijing Xie , Fangyuan Su , Zonglin Yi , Quangui Guo , Cheng-Meng Chen

硬碳形成的闭孔在高原地区钠储存中发挥着重要作用。然而，不同结构特征对钠离子扩散到闭孔中的影响仍不清楚。在此，通过改变芳香族和多糖组分的比例，进行前体重构策略来调节碳微结构，包括层间距、缺陷浓度和闭孔体积。芳香结构部分倾向于形成缺陷较少、层间距较大、闭孔体积较小的无序碳，而多糖组分则倾向于形成缺陷较多、层间距较小、闭孔体积较大的无序碳。通过微观结构特征与0.1 V以下储钠能力的相关性分析，发现插层能力与石墨相域的比例成正比，而在较低电位下出现的孔填充能力随着缺陷浓度的增加而逐渐减小。同离子排斥效应，与短程微晶和闭孔体积不存在线性相关性。具有合适层间距和缺陷浓度的优化样品表现出241.7 mAh/g的高平台容量。这项工作为闭孔钠存储性能的开发提供了见解。

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New insights into the effect of hard carbons microstructure on the diffusion of sodium ions into closed pores

Closed pores formed in hard carbons play an essential role in sodium storage at plateau region. However, the effect of different structural features on the diffusion of sodium ions into closed pores remains unclear. Herein, a precursor reconstruction strategy is conducted to regulate carbon microstructures including interlayer spacing, defect concentration, and closed pore volume by changing the ratio of aromatic and polysaccharide components. Aromatic structure parts tend to develop disordered carbons with fewer defects, larger interlayer spacing, and smaller closed pore volume, while polysaccharide components prefer to form disordered carbons with more defects, smaller interlayer spacing, and larger closed pore volume. Through the correlation analysis of microstructure features and the sodium storage capacity below 0.1 V. It finds that the intercalation capacity is proportional to the ratio of -graphitic domains, whereas the pore filling capacity appeared at lower potential gradually decreases with the increasing defect concentration due to homo-ionic repulsion effect, without linear correlation with short-range microcrystalline and closed pore volume. The optimized sample with suitable interlayer spacing and defect concentration exhibits a high plateau capacity of 241.7 mAh/g. This work provides insights into the exploitation of closed pore sodium storage performance.

更新日期：2023-11-03

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