Jose Ramón Fernández Gamboa

The search for advanced solid‑state electrolytes is central to the development of next generation alkali ion batteries, as they promise higher energy density, improved safety, and longer cycle life as compared to conventional liquid systems. Orthorhombic Li2MgX4 (X = Cl, Br) compounds are investigated using atomistic simulations to determine its lattice geometry, defect chemistry and transport properties. Computational methods employed reproduce experimental lattice parameters with high accuracy, while bromide substitution expands polyhedral volumes and introduces novel Li+ Wyckoff occupations, underscoring the sensitivity of cation coordination to halide size. Both compounds are wide band gap insulators, with Li2MgCl4 exhibiting greater rigidity, ductility and elastic anisotropy, while Li2MgBr4 shows enhanced shear resistance and isotropic stiffness but reduced machinability. Defect energetics highlight Schottky pairs as the most favorable intrinsic disorder, whereas bromide substitution lowers formation energies and migration barriers. Of the extrinsic dopants, Zn2+ emerges as the most effective divalent dopant, while both Al3+ and Ga3+ provide with the most favorable trivalent strategy in stabilizing defect complexes and enhancing Li+ mobility. Transport evaluations confirm the decisive role of halide chemistry: at 25°C, Li2MgCl4 exhibits a conductivity of (3.26×10-5 S/cm) with an activation energy of 0.36 eV, whereas Li2MgBr4 achieves 4.18×10-5 S/cm with more favorable activation energy of 0.21 eV. Computed results demonstrate that bromide substitution tends to enhance room temperature Li⁺ transport by nearly two orders of magnitude as compared to the chloride analogues reported in the literature, thus establishing Li2MgCl4 and particularly Li2MgBr4 as effective solid‑state electrolyte candidates and providing us with clear chemical design rules for cost effective halide conductors in next generation alkali ion batteries.

In this study, density functional theory calculations were performed to investigate the site preference of Ti4+ and its impact on the structural, electronic, and magnetic properties of BaFe12–xTixO19 (x = 0.0, 0.5,1.0,1.5 and 2.0). In parallel, BaFe12–xTixO19 nanopowders (x = 0.0, 0.1, 0.3, 0.5, 0.7 and 0.9) were synthesized via the co-precipitation method and characterized by X-ray diffraction and vibrating sample magnetometry, to compared and validate the theoretical investigation. Calculations in structures with substitutions in the five Fe3+ sites revealed that Ti4+ preferentially occupies the 12k sites, followed by the 2b site, while Fe2+ ions are localized exclusively at the 12k sites. Both theoretical and experimental results show that the lattice parameters a and c increase with increasing Ti4+ concentration. In the electronic structure, the main effect of Ti4+ is to induce an increase in the band gap of the spin-up semiconductor channel, while the spin-down channel becomes metallic. Exchange integral calculations demonstrated that the 2b-4f2, 2b-12k, 4f1-12k, and 4f2-12k interactions are the most significantly affected. The magnetocrystalline anisotropy energy calculations revealed a transition from uniaxial to planar magnetic anisotropy near x = 1.0. Concerning magnetic properties, the presence of Ti4+ at the 12k and 2b sites led to reductions in saturation magnetization, the magnetocrystalline anisotropy constant and the anisotropy field. Experimental magnetic results confirmed the theoretical behavior.

This paper presents a comprehensive computational investigation of the orthorhombic P 2 ₁ 2 ₁ 2 ₁ phase of NaAlBr ₄ as a halide-based solid-state electrolyte for sodium-ion batteries.

Computational study revealing the potential of an Na₂MgCl₄ solid-state electrolyte, including its crystal structure, ion arrangement, stability, conductivity, and application, in Na-ion batteries.

Potential of alkali hexazirconates as electrode materials for alkali ion batteries.

In this theoretical study, we harnessed advanced atomistic computations to unravel several features of Na ₂ Mg ₃ Cl ₈ , an unexplored but promising chloride compound for solid-state electrolytes in Na-batteries.