碳化
阳极
材料科学
碳纤维
化学工程
电化学
比表面积
电解质
介孔材料
粒子(生态学)
球体
扩散
动力学
电流密度
粒径
纳米技术
电极
复合材料
化学
催化作用
有机化学
扫描电子显微镜
工程类
物理化学
地质学
物理
海洋学
复合数
热力学
量子力学
天文
作者
Wenlong Shao,Fangyuan Hu,Siyang Liu,Tianpeng Zhang,Ce Song,Zhihuan Weng,Jinyan Wang,Xigao Jian
标识
DOI:10.1016/j.jechem.2020.06.031
摘要
The electrochemical performance of hard carbon in sodium storage is still limited by its poor cycling stability and rate capability because of the sluggish kinetics process. In this study, we use a simple and effective method to accelerate the kinetics process by engineering the structure of the electrode to promote its surface and near-surface reactions. This goal is realized by the use of slightly aggregated ultra-small carbon spheres. The large specific surface area formed by the small spheres can provide abundant active sites for electrochemical reactions. The abundant mesopores and macropores derived from the secondary particle piled structure of the carbon spheres could facilitate the transport of electrolytes, shorten the diffusion distance of Na+ and accommodate the volume expansion during cycling. Benefiting from these unique structure features, PG700-3 (carbon spheres with the diameters of 40–60 nm carbonized at 700 °C) exhibits high performance for sodium storage. A high reversible capacity of 163 mAh g−1 could be delivered at a current density of 1.0 A g−1 after 100 cycles. Interestingly, at a current density of 10.0 A g−1, the specific capacity of PG700-3 gradually increases to 140 mAh g−1 after 10 000 cycles, corresponding to a capacity retention of 112%. Given the enhanced kinetics of SIBs reactions, PG700-3 exhibits an excellent rate capability, i.e., 230 and 138 mAh g−1 at 0.1 and 5.0 A g−1, respectively. This study provides a facile method to attain high performance anode materials for SIBs. The design strategy and improvement mechanism could be extended to other materials for high rate applications.
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