Low‐Defect and Low‐Porosity Hard Carbon with High Coulombic Efficiency and High Capacity for Practical Sodium Ion Battery Anode,Advanced Energy Materials

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Low‐Defect and Low‐Porosity Hard Carbon with High Coulombic Efficiency and High Capacity for Practical Sodium Ion Battery Anode
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2018-03-25 , DOI: 10.1002/aenm.201703238
Lifen Xiao ₁ , Haiyan Lu ₂ , Yongjin Fang ₂ , Maria L. Sushko ₃ , Yuliang Cao ₂ , Xinping Ai ₂ , Hanxi Yang ₂ , Jun Liu ₃

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Hard carbon is regarded as the most promising anode material for commercialization of Na ion batteries because of its high capacity and low cost. At present, the practical utilization of hard carbon anodes is largely limited by the low initial Coulombic efficiency (ICE). Na ions have been found to adopt an adsorption–insertion storage mechanism. In this paper a systematic way to control the defect concentration and porosity of hard carbon with similar overall architectures is shown. This study elucidates that the defects in the graphite layers are directly related to the ICE as they would trap Na ions and create a repulsive electric field for other Na ions so as to shorten the low‐voltage intercalation capacity. The obtained low defect and porosity hard carbon electrode has achieved the highest ICE of 86.1% (94.5% for pure hard carbon material by subtracting that of the conductive carbon black), reversible capacity of 361 mA h g⁻¹, and excellent cycle stability (93.4% of capacity retention over 100 cycles). This result sheds light on feasible design principles for high performance Na storage hard carbon: suitable carbon layer distance and defect free graphitic layers.

中文翻译：

实用钠离子电池阳极具有高库仑效率和高容量的低缺陷，低孔隙率的硬碳

硬碳由于其高容量和低成本而被认为是Na离子电池商业化最有希望的负极材料。目前，硬碳阳极的实际使用在很大程度上受到低初始库仑效率（ICE）的限制。已发现钠离子采用吸附插入存储机制。在本文中，展示了一种控制总体结构相似的硬碳缺陷浓度和孔隙率的系统方法。这项研究阐明了石墨层中的缺陷与ICE直接相关，因为它们会捕获Na离子并为其他Na离子产生排斥电场，从而缩短低压插层能力。所获得的低缺陷和低孔隙率的硬碳电极已达到86.1％的最高ICE（94。^-1和出色的循环稳定性（在100个循环中占93.4％的容量保持率）。该结果阐明了高性能Na存储硬碳的可行设计原理：合适的碳层距离和无缺陷的石墨层。

更新日期：2018-03-25

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