Key Laboratory of Automobile Materials, Ministry of Education, and College of Materials Science and Engineering, Jilin University , Changchun, 130012, China.
Department of Physics and Astronomy, University of Missouri , Columbia, Missouri 65211-7010, United States.
ACS Appl Mater Interfaces. 2017 May 24;9(20):17076-17084. doi: 10.1021/acsami.7b02972. Epub 2017 May 12.
Layered carbon is a likely anode material for Na-ion batteries (NIBs). Graphitic carbon has a low capacity of approximately 35 (mA h)/g due to the formation of NaC. Using first-principles methods including van der Waals interactions, we analyze the adsorption of Na ions and clusters on graphene in the context of anodes. The interaction between Na ions and graphene is found to be weak. Small Na clusters are not stable on the surface of pristine graphene in the electrochemical environment of NIBs. However, we find that Na ions and clusters can be stored effectively on defected graphene that has double vacancies. In addition, the adsorption energy of small Na clusters near a double vacancy is found to decrease with increasing cluster size. With high concentrations of vacancies the capacity of Na on defective graphene is found to be as much as 10-30 times higher than that of graphitic carbon.
层状碳可能是钠离子电池 (NIBs) 的阳极材料。由于 NaC 的形成，石墨碳的容量较低，约为 35(mA h)/g。本研究采用包含范德华相互作用的第一性原理方法，在钠离子电池的电化学环境下，分析了钠离子和团簇在石墨烯上的吸附。结果表明，钠离子与石墨烯的相互作用较弱。在 NIBs 的电化学环境中，较小的 Na 团簇在原始石墨烯表面不稳定。然而，我们发现 Na 离子和团簇可以在具有双空位的缺陷石墨烯上有效储存。此外，我们发现，双空位附近小 Na 团簇的吸附能随团簇尺寸的增加而降低。在空位浓度较高的情况下，缺陷石墨烯上 Na 的容量比石墨碳高 10-30 倍。
