Graphene-based nanomaterials have attracted great attention for energy storage application in supercapacitors and batteries, along with challenges and perspectives in the exciting field; however, the Li ion batteries with long cycling stability remain a major impediment. In order to enhance the Li+ ion adsorption, we employ density functional theory to investigate the adsorption of Li+ ion with hydrogen-, fluorine-, chlorine- and bromine-terminated pristine sheet and the corresponding Stone–Thrower–Wales and divacancy defect-incorporated graphene sheet. Our results reveal that fluorine termination enhances Li+ ion adsorption compared to H- and other halogen-terminated graphene sheets. On the other hand, Li+ ion adsorption energy is increased on introducing the fluorine termination in both pristine and defected graphene sheets, while Li+ ion adsorption is more in the divacancy-defected graphene. From the density of states analysis, the Fermi level shows 1.9 eV shift toward the valence band for fluorine termination in both pristine and defected graphene sheets. Fluorine termination is shown to have a significant variation in the valence band than the other halogen atoms, and hence, it offers efficient material energy conversion and storage.

中文翻译：

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边缘终止对原始和缺陷石墨烯片的 Li+ 离子吸附的影响

石墨烯基纳米材料在超级电容器和电池中的储能应用引起了极大的关注，同时也带来了令人兴奋的领域的挑战和前景；然而，具有长循环稳定性的锂离子电池仍然是一个主要障碍。为了增强锂离子的吸附，我们采用密度泛函理论来研究锂离子与氢、氟、氯和溴封端的原始片材以及相应的 Stone-Thrower-Wales 和双空位缺陷结合的石墨烯的吸附床单。我们的结果表明，与 H- 和其他卤素封端的石墨烯片相比，氟封端增强了 Li+ 离子的吸附。另一方面，在原始和有缺陷的石墨烯片中引入氟终止后，Li+ 离子的吸附能增加，而在双空位缺陷的石墨烯中，Li+ 离子吸附更多。从状态密度分析来看，费米能级显示出 1.9 eV 向价带移动，以在原始和有缺陷的石墨烯片中进行氟终止。氟终止在价带中显示出比其他卤素原子显着的变化，因此，它提供了有效的材料能量转换和存储。