Gharehzadeh Shirazi Sobira, Nasrollahpour Mokhtar, Vafaee Mohsen
Department of Chemistry, Tarbiat Modares University, 14115-175 Tehran, I. R. Iran.
ACS Omega. 2020 Apr 22;5(17):10034-10041. doi: 10.1021/acsomega.0c00422. eCollection 2020 May 5.
In this work, by density functional theory (DFT) calculations, sp-sp-hybridized boron-doped graphdiyne (BGDY) nanosheets have been investigated as an anode material for sodium storage. The density of states (DOS) and band structure plots show that substituting a boron atom with a carbon atom in an 18-atom unit cell converts the semiconductor pristine graphdiyne (GDY) to metallic BGDY. Also, our calculations indicate that, due to the presence of boron atoms, the adsorption energy of BGDY is more than that of GDY. The diffusion energy barrier calculations show that the boron atom in BGDY creates a more suitable path with a low energy barrier for sodium movement. This parameter is important in the rate of charge/discharge process. On the other hand, the projected density of states (PDOS) plots show that sodium is ionized when adsorbed on the electrode surface and so Na-BGDY interaction has an electrostatic character. This type of interaction is necessary for the reversibility of adsorption in the discharge mechanism. Finally, the calculation of the theoretical capacity shows an increase in BGDY (872.68 mAh g) in comparison with that in GDY (744 mAh g). Thus, from comparison of different evaluated parameters, it can be concluded that BGDY is a suitable anode material for sodium-ion batteries.
在本工作中，通过密度泛函理论（DFT）计算，对sp-sp杂化的硼掺杂石墨二炔（BGDY）纳米片作为钠存储的阳极材料进行了研究。态密度（DOS）和能带结构图表明，在一个18原子的晶胞中用硼原子取代碳原子会将半导体原始石墨二炔（GDY）转变为金属性的BGDY。此外，我们的计算表明，由于硼原子的存在，BGDY的吸附能大于GDY的吸附能。扩散能垒计算表明，BGDY中的硼原子为钠的移动创造了一条具有低能垒的更合适路径。该参数在充放电过程速率中很重要。另一方面，投影态密度（PDOS）图表明，钠吸附在电极表面时会发生电离，因此Na-BGDY相互作用具有静电特性。这种相互作用类型对于放电机制中吸附的可逆性是必要的。最后，理论容量的计算表明，与GDY（744 mAh g）相比，BGDY的理论容量有所增加（872.68 mAh g）。因此，通过比较不同评估参数可以得出结论，BGDY是一种适用于钠离子电池的阳极材料。
