Sodiated two-dimensional 2H-ZrO2: Structural, electronic, interfacial and thermoelectric insights for high-performance battery applications

Abstract

Two-dimensional (2D) materials with excellent carrier mobility and broadband range are instinctively appropriate for next-generation sodium-ion batteries (SIBs). The study presents an innovative anode design leveraging the 2D 2H-ZrO₂ for SIBs. Density functional theory has been employed to investigate the aforementioned anode material properties including theoretical capacity, diffusion barrier energy, and charge transfer of adsorbed system (Na@2H-ZrO₂). Notably, the shift from semiconducting to half metallic nature of 2H-ZrO₂ after Na adsorption facilitates a high electronic conductivity. A minimal lattice change of 0.67 % along with high diffusivity and rapid charge transfer characteristics, as indicated by a low diffusion barrier of 0.9 eV, underscores 2H-ZrO₂ suitability as an anode material. Moreover, an exceptional sodium storage capacity of 435 mAh g⁻¹ is achieved by sodiating both sides of 2H-ZrO₂. The planar charge density difference (PCDD) endorses accumulation of charge density at the interface. Additionally, to evaluate the effectiveness of proposed anode material, thermoelectric properties are calculated over a range of temperatures. Na@2H-ZrO₂ system produces thermoelectric effect at room temperature (300 K). The enhanced Seebeck coefficient, improved electronic conductivity, higher power factor, and increased figure of merit for Na@2H-ZrO₂ not only boost electronic conduction, but also contribute to the overall efficiency of the anode.