Theoretical Investigation of Two-Dimensional 1T-ZrSe₂ as Anode Material for Li-Ion Batteries

Two-dimensional structures have garnered increased attention in the stage of high-quality anode material due to their high surface area, tunable properties, mechanical flexibility, fast ion diffusion and chemical stability. Transition metal dichalcogenides (TMD) are among the two-dimensional material families with immense potential in terms of anode materials for metal ion batteries. 1T-ZrSe2 is a promising member of this material family. In this paper, through density functional theory (DFT) calculations, the interaction between Li and monolayer 1T- <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{ZrSe}_{2}$</tex> is investigated. This work includes structural optimizations, electronic band structures, diffusion profile, theoretical capacity, and open circuit voltage. The semiconducting pristine monolayer shows metallic property after <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{L i}$</tex> adsorption. Multiple adsorption sites have been verified through negative adsorption energies, and the Bader charge analysis shows charge transfer of 0.8843 e indicating strong ionic interaction between the monolayer and the metal ion. The diffusion profile consists of an energy barrier of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0. 2 2}$</tex> eV which ensures fast charging and discharging. The monolayer is shown to adsorb two layers of Li ions, which leads to an OCV of 0.76 V and a theoretical capacity of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$215 \text{mAh} / \mathrm{g}$</tex>. AIMD simulations are carried out to verify the structural stability of the structure in 300 K and 600 K temperature. Thus, this study signifies the applicability of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1 \mathrm{T}-\text{ZrSe}_{2}$</tex> as an anode material for Li-ion batteries for applications specializing in fast rates and moderate storage capacities.