Optimized Li storage performance of B, N doped graphyne as Li-ion battery anode materials

Abstract

As the economy grows and the environment deteriorates, the renewable energy is urgently needed. The advanced energy storage technology in electronic equipment, electric vehicle, smart grid, etc. becomes more significant. For example, the rechargeable batteries, hydrogen storage media, supercapacitors, the new energy storage devices have received much attention today. The anodes of the lithium ion battery (LIB), as the main body of charging and discharging, should be most important. The ideal anode material for LIBs is required to possess a higher Li capacity and a lower volume expansion. Good reversibility and high Li capacity are balanced necessarily in the electrode material. The poor cycling performance of LIB is usually due to the severe volume expansion of anode in lithiation/delithiation process. In this paper, the Li storage performance of B and N doped graphyne is explored by using the density functional theory method. The Perdew-Burke-Ernzerhof functional of the generalized gradient approximation is chosen. The calculations indicate that the doping of B atoms can enhance the adsorption strength between the Li atom and the graphyne, which can greatly increase the Li storage capacity. The Li storage capacity of B doped graphyne can reach as high as 2061.62 mAh/g, which is 2.77 times that of pristine monolayer graphyne. Meanwhile, the B doping reduces the out-plane diffusion energy barrier of Li, but increases the in-plane diffusion energy barrier slightly by 0.1 eV. On the other hand, the doping of N atoms reduces the interaction between Li and graphyne, however, the Li capacity also increases to 1652.12 mAh/g because the number of the available Li adsorption sites increases. Moreover, the doping of N atoms greatly improves the diffusion performance of Li on graphyne. The in-plane diffusion energy barrier drops to 0.37 eV, and thus the charge-discharge performance of the N doping graphyne is well improved. Therefore, the doping of B and N atoms can remarkably improve the performance of graphyne as the LIB anodes. The remarkable performance of B and N doped graphdiyne shows that it will become a promising LIB anode in the future. The present research can provide a good theoretical basis and thus conduce to guiding the developing of good Li storage materials, and can also supply strong background for experimental researches.

Graphynes and Graphdiynes for Energy Storage and Catalytic Utilization: Theoretical Insights into Recent Advances

“…B doping can effectively enhance the interaction between Li and γ-GY, resulting in an increased Li capacity of 2061.62 mAh g −1 . 217 Additionally, N doping can increase the number of Li adsorption sites and thus increase the Li storage capacity to 1652.12 mAh g −1 . 217 With the increase in the N content of γ-GY (GY, PY-GY, PM-GY, and TA-GY, as shown in Figure 36e), both theoretical and experimental studies show that the band gap becomes smaller, while the charge concentration and the Li storage capacity increase.…”

“…217 Additionally, N doping can increase the number of Li adsorption sites and thus increase the Li storage capacity to 1652.12 mAh g −1 . 217 With the increase in the N content of γ-GY (GY, PY-GY, PM-GY, and TA-GY, as shown in Figure 36e), both theoretical and experimental studies show that the band gap becomes smaller, while the charge concentration and the Li storage capacity increase. 218 γ-GYNTs, especially (2,2)-γ-GYNTs, are also theoretically predicted to have a high Li storage capacity (2232 mAh g −1 ).…”

“…The Li storage capacity of GYF can be also improved by chemical modification. B doping can effectively enhance the interaction between Li and γ-GY, resulting in an increased Li capacity of 2061.62 mAh g –1 . Additionally, N doping can increase the number of Li adsorption sites and thus increase the Li storage capacity to 1652.12 mAh g –1 .…”

Probing structural and electronic properties of divalent metal Mg n+1 and SrMg n (n = 2–12) clusters and their anions

“…[1][2][3][4][5][6][7] It is worth mentioning that density functional theory (DFT) with appropriate functional and basis sets is known as an efficient method for clustering study. [8][9][10][11] Taking the research of neutral and charged Mg n clusters for example, Xia et al [6] studied the aromatic homonuclear Mg 17 cluster by using the B3PW91 functional with the 6-311+G(d) basis set, and their results displayed that the Mg 17 cluster is the first neutral locally π-aromatic homonuclear all-metal cluster. Belyaev et al [7] reported the electronic, spectral, structural, and thermodynamic characteristics of Mg n (n = 2-31) clusters at B3PW91/6-31G (d), B3PW91/6-311+G (2d) set levels, then they revealed that in the range of Mg 2 -Mg 31 , the atomization energy and band gap energy have significant nonmonotonic changes, and gradually approach to the atomization energy and band gap energy of ideal metal.…”

“…[2][3][4][5][6][7][8][9][10][11][12] clusters are systematically investigated by using the CALYPSO structure prediction code combined with DFT calculations. A great many of low energetic isomers are converged and the most stable structures are confirmed by comparing their total energies for different cluster sizes of the SrMg 0/− n (n = 2-12).…”