Be掺杂石墨双炔作为锂离子电池负极材料的第一性原理研究

First principles study of Be-doped graphdiyne as anode material for lithium-ion batteries

采用基于密度泛函理论的第一性原理方法,研究了Be在不同位置掺杂的石墨双炔作为锂离子电池负极材料的性能.通过计算不同掺杂浓度下石墨双炔的形成能和内聚能,表明Be掺杂的石墨双炔具有很好的实验合成前景.更重要的是,掺Be后的石墨双炔具有良好的导电性能.Be掺杂的石墨双炔对单个锂的吸附能为-4.22 eV,相较于硼,氮掺杂石墨双炔以及本征石墨双炔大幅度提升.随着储锂数量的增加,其对锂的吸附能依旧大于固体锂的内聚能,并且平均开路电压在0—1 V之间,充分保证了电池的安全性.除此之外,将储锂容量提升为881 mAh/g,是未掺杂石墨双炔的1.14倍,是石墨的2.36倍.同时,锂在Be掺杂的石墨双炔上扩散性能也有所提升.对于C_(Ⅲ)位掺杂体系,通过研究低锂浓度、中锂浓度、高锂浓度阶段的离子输运.研究发现随着锂浓度的增大,扩散势垒分别为0.38,0.44,0.77 eV,锂离子的移动变得困难,但依然优于其他元素掺杂的石墨双炔.综上所述,铍掺杂石墨双炔作为优异的锂离子电池负极材料具有很大潜力.

The performances of beryllium-doped graphdiyne(GDY),which is used as an anode material for lithiumion batteries at various doping sites,are investigated by first-principles methods based on density functional theory.Calculations of the formation energy and cohesive energy of GDY at different doping concentrations indicate that beryllium-doped GDY has excellent prospects for experimental synthesis.More importantly,the beryllium-doped GDY exhibits good electrical conductivity.The adsorption energy for a single lithium atom on 0-1-3.64-3.66-2.62-2.25-4 beryllium-doped GDY is–4.22 eV,which is significantly higher than that for boron,nitrogen-doped GDY,and intrinsic GDY.As the number of stored lithium atoms increases,the adsorption energy remains greater than the cohesive energy of solid lithium,and the average open-circuit voltage stays between 0 and 1 V,ensuring the safety of the battery.Additionally,the lithium storage capacity is increased to 881 mAh/g,which is 1.14 times that of undoped GDY and 2.36 times that of graphite.Meanwhile,the diffusion performance of lithium on beryllium-doped GDY is also enhanced.For the C_(Ⅲ) site doping system,by studying the ion transports at low,medium,and high lithium concentrations,we find that as the lithium concentration increases,the diffusion barriers are 0.38,0.44,and 0.77 eV,respectively,making lithium ion movement more difficult,but still superior to those of other element-doped GDY.In summary,beryllium-doped GDY has great potential as an excellent anode material for lithium-ion batteries.