Chalcogen effects and cathodic properties of scandium-based materials for sodium-ion batteries

Sodium-ion batteries emerged as a sustainable alternative to overcome the cost, availability, safety, and energy density concerns challenged by existing commercialized lithium-ion battery technology. This paper focuses on modeling new layered sodium scandium chalcogenides (O, S, and Se), prepared by the solid-state synthesis method as electrode materials for large-scale energy storage. We examined and compared the structural, electronic, cathodic, and transport properties of NaScX2 layered materials. We continued our investigation into the stability of these cathode materials for the charge–discharge process. Among the chalcogenide materials, NaScSe2 exhibited the lowest estimated energy barrier for Na-ion diffusion, with values of 0.57 eV via a single vacancy mechanism and 0.21 eV for a divacancy mechanism. As we go to the higher ionic radii of divalent anions, it shows higher electric polarizability. Hence, layered selenide has a higher capability to deform the electron charge density of anion by the nearby Na cations. This influences the mobility of diffusing alkali metal cations.