Expanded graphite as superior anode for sodium-ion batteries
Expanded graphite as superior anode for sodium-ion batteries
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DOI：
10.1038/ncomms5033
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发表时间：
2014-06-01
影响因子：
16.6
通讯作者：
Wang, Chunsheng
中科院分区：
文献类型：
--
作者：
Wen, Yang;He, Kai;Wang, Chunsheng
石墨作为商用锂离子电池最常用的负极，据报道当用作钠离子电池负极时，其容量非常低。众所周知，层间距不足严重阻碍了Na+在石墨中的电化学插入。在这里，我们报道了膨胀石墨作为钠离子电池阳极。通过在石墨上氧化和部分还原制备膨胀石墨，膨胀石墨的层间晶格距离扩大到4.3埃，但仍保持与石墨类似的长程有序层状结构。原位透射电镜证实了钠离子可以可逆地插入和从膨胀石墨中提取。恒流研究表明，膨胀石墨在电流密度为20mAg（-1）时可提供284mAhg（-1）的高可逆容量，在100mAg（-1）时可保持184mAhg（-1）的容量，在循环2000次后仍能保持73.92%的容量。
Graphite, as the most common anode for commercial Li-ion batteries, has been reported to have a very low capacity when used as a Na-ion battery anode. It is well known that electrochemical insertion of Na+ into graphite is significantly hindered by the insufficient interlayer spacing. Here we report expanded graphite as a Na-ion battery anode. Prepared through a process of oxidation and partial reduction on graphite, expanded graphite has an enlarged interlayer lattice distance of 4.3 angstrom yet retains an analogous long-range-ordered layered structure to graphite. In situ transmission electron microscopy has demonstrated that the Na-ion can be reversibly inserted into and extracted from expanded graphite. Galvanostatic studies show that expanded graphite can deliver a high reversible capacity of 284mAhg(-1) at a current density of 20mAg(-1), maintain a capacity of 184mAhg(-1) at 100mAg(-1), and retain 73.92% of its capacity after 2,000 cycles.