Theoretical study of the ZrS₂/PtSe₂ heterojunction as an anode material for magnesium-ion batteries

This study systematically explored the potential of the ZrS₂/PtSe₂ heterojunction as an anode material for magnesium-ion batteries (MIBs) using first-principles calculations. The results show that the heterojunction has excellent structural stability, with a binding energy of -2.512 eV, and is thermodynamically stable. Its electronic properties feature a Type-II band alignment and an indirect band gap of 1.288 eV. Applying biaxial strain effectively tunes the band gap, resulting in values of 1.756 eV under -5% strain and 0.085 eV under 5% strain. In terms of electrochemical performance, the heterojunction exhibits a strong adsorption energy for Mg atoms at -1.432 eV, which is significantly higher than that of the individual monolayers. The calculated average open-circuit voltage is 0.637 V, and the theoretical capacity reaches 841.62 mAh/g. Additionally, Mg ions show an exceptionally low migration barrier on the heterojunction surface, as low as 0.057 eV. These characteristics indicate that the ZrS₂/PtSe₂ heterojunction is an excellent candidate for anode materials in MIBs.

First-principles calculations were carried out using the CASTEP software. The exchange-correlation functional utilized the Perdew-Burke-Ernzerhof approach within the generalized gradient approximation. For more precise electronic property evaluations, the hybrid functional HSE06 was applied. Structure optimization and total energy computations employed Monkhorst-Pack k-point grids of 9 × 9 × 1 for monolayers and 8 × 8 × 1 for the heterojunction. The plane-wave basis set had an energy cutoff of 520 eV. The convergence threshold for electronic energy in the self-consistent field cycle was set at 10^-6 eV.