Theoretical study on the effect of torsional deformation on WTe₂ as a cathode material for calcium ion batteries

In this study, the electronic structure and diffusion barrier of the Ca-adsorbed WTe₂ system under different torsion angles were calculated based on the first-principles method. The results show that the structure and properties of the pure WTe₂ system and Ca-adsorbed WTe₂ system are affected by torsional deformation. When the torsion angle is 6°, the intrinsic WTe₂ changes from a direct band gap to an indirect band gap. The torsional deformation does not change the metallicity of the Ca-adsorbed WTe₂ system. The Ca-d state electrons contribute to the electron density of WTe₂. The calculation of the diffusion barrier shows that the torsion deformation promotes the diffusion of calcium on the surface of WTe₂. This study provides a theoretical basis for the regulation of electrode materials.

In this study, Materials Studio 8.0 software was used to construct the WTe₂ model and Ca-adsorbed WTe₂ model, and CASTEP module was used for first-principles calculation.