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Register a new userLithium intercalation drives remarkable mechanical properties deterioration in bulk and single-layered phosphorus: A first-principles study
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It is of critical importance to understand the mechanical properties change of electrode materials during lithium intercalation in the mechanical design of Li-ion batteries, for the purpose of the high reliability and safety in their applications. Here, we investigated the mechanical properties of both bulk and single layer phosphorus during the lithium intercalation process by using the first-principles calculations. Our results show that the Youngs modulus of bulk and layered phosphorus strongly depends on the lithium intercalation. The mechanical bearing capacities, such as critical strain and stress, are significantly reduced by several times after lithium intercalation in both bulk and single layer phosphorus, which may reduce the reliability of Li-ion batteries. Our findings suggest that this remarkable mechanical properties deterioration during Li intercalation should be considered carefully in the mechanical design of Li-ion batteries, in order to keep they working reliably and safely in the charge-discharge process.
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We calculate the density of states (DOS) and the Mulliken population of the diamond and the co-doped diamonds with different concentrations of lithium (Li) and phosphorus (P) by the method of the density functional theory, and analyze the bonding situations of the Li-P co-doped diamond thin films and the impacts of the Li-P co-doping on the diamond conductivities. The results show that the Li-P atoms can promote the split of the diamond energy band near the Fermi level, and improve the electron conductivities of the Li-P co-doped diamond thin films, or even make the Li-P co-doped diamond from semiconductor to conductor. The effect of Li-P co-doping concentration on the orbital charge distributions, bond lengths and bond populations is analyzed. The Li atom may promote the split of the energy band near the Fermi level as well as may favorably regulate the diamond lattice distortion and expansion caused by the P atom.
We present a first-principles investigation of structural and elastic properties of experimentally observed phases of bulk SrRuO$_3$ - namely orthorhombic, tetragonal, and cubic - by applying density functional theory (DFT) approximations. At first, we focus our attention on the accuracy of calculated lattice constants in order to find out DFT approaches that best represent the crystalline structure of SrRuO$_3$, since many important physical quantities crucially depend on change in volume. Next, we evaluate single-crystal elastic constants, mechanical stability, and macroscopic elastic parameters trying to at least partially compensate for the existing lack of information about these fundamental features of SrRuO$_3$. Finally, we analyze the anomalous behavior of low-temperature orthorhombic phase under $C_{44}$ related shear deformation. It turns out that at critical strain values the system exhibits a distinct deviation from the initial behavior which results in an isosymmetric phase transition. Moreover, under $C_{44}$ related shear deformation tetragonal SrRuO3 becomes mechanically unstable raising an open question of what makes it experimentally observable at high temperatures.
By means of first-principles calculations, the structural stability, mechanical properties and electronic structure of the newly synthesized incompressible Re2C, Re2N, Re3N and an analogous compound Re3C have been investigated. Our results agree well with the available experimental and theoretical data. The proposed Re3C is shown to be energetically, mechanically and dynamically stable and also incompressible. Furthermore, it is suggested that the incompressibility of these compounds is originated from the strong covalent bonding character with the hybridization of 5d orbital of Re and the 2p orbital of C or N, and a zigzag topology of interconnected bonds, e.g., Re-Re, Re-C or Re-N bonding.
The structure and mobility of dislocations in the layered semiconductor InSe is studied within a multiscale approach based on generalized Peierls--Nabarro model with material-specific parametrization derived from first principles. The plasticity of InSe turns out to be attributed to peculiarities of the generalized stacking fault relief for the interlayer dislocation slips such as existence of the stacking fault with a very low energy and low energy barriers. Our results give a consistent microscopic explanation of recently observed [Science {bf 369}, 542 (2020)] exceptional plasticity of InSe.
As a storage material for Li-ion batteries, graphene/molybdenum disulfide (Gr/MoS2) composites have been intensively studied in experiments. But the relevant theoretical works from first-principles are lacking. In the current work, van-der-Waals-corrected density functional theory calculations are performed to investigate the interaction of Li in Gr/MoS2 composites. Three interesting features are revealed for the intercalated Gr/Li(n)/MoS2 composites (n = 1 to 9). One is the reason for large Li storage capacity of Gr/MoS2: due to the binding energies per Li atom increase with the increasing number of intercalated Li atoms. Secondly, the band gap opening of Gr is found, and the band gap is enlarged with the increasing number of intercalated Li atoms, up to 160 meV with nine Li; hence these results suggest an efficient way to tune the band gap of graphene. Thirdly, the Dirac cone of Gr always preserve for different number of ionic bonded Li atoms.
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