Discovery of inaccessible supersaturated metastable Li3VO4–Li2MoO4 solid solutions via spray drying for high-performance anodes

Abstract

A previously inaccessible metastable solid-solution phase, Li_3−xV_1−xMo_xO₄ (LVMoO), has been successfully synthesized for the first time over a remarkably wide compositional range (0.25 ≤ x ≤ 0.75). This new phase forms a single, impurity-free solid solution adopting a phenakite-type lattice, extending compositional limits far beyond equilibrium thermodynamic boundaries. The breakthrough is enabled by a kinetically driven spray-drying process in which ultrafast solvent evaporation within less than one second forces the simultaneous co-precipitation of V and Mo species. This suppresses sequential crystallization and prevents phase segregation, thereby stabilizing supersaturated nonequilibrium states. Operating at only 160 °C, the process requires no post-calcination and yields homogeneous, waste-free powders suitable for large-scale production. XRD confirms continuous lattice incorporation of V and Mo across the solid-solution series, while SEM-EDX analyses reveal composition-dependent nanostructures with uniform elemental distributions. A representative composition, Li_2.5V_0.5Mo_0.5O₄ (x = 0.5), delivers a high reversible capacity of 650 mAh g⁻¹ together with exceptional rate performance: 411 mAh g⁻¹ during delithiation at 15 A g⁻¹, and, strikingly, 326 mAh g⁻¹ during lithiation at 5 A g⁻¹. These results establish nonequilibrium spray drying as a significant and scalable synthetic route for supersaturated LVMoO solid solutions that unite high energy, high power, and long-term durability.