A New Spinel Chloride Solid Electrolyte with High Ionic Conductivity and Stability for Na-Ion Batteries

Abstract

Halide materials are of current interest as solid electrolytes for all-solid-state sodium-ion batteries (ASIBs), due to their good balance between ionic conductivity and electrochemical stability. In this work, by using density functional theory combined with deep potential model and grand potential phase diagram analysis, we report a new spinel chloride (Na 2 Y 2/3 Cl 4 ) and systemically evaluate its potential for the solid electrolyte. The spinel Na 2 Y 2/3 Cl 4 exhibits a high ionic conductivity of 0.94 mS/cm at room temperature and has a three-dimensional isotropic diffusion network comprised of face-sharing octahedra and tetrahedra. Further analysis of the diffusion mechanism indicates that the Na + conductivity mainly derives from Na ions in the 8a site while the Na ions in the 16d site are mainly used for forming the rhombus skeleton. Besides, the spinel Na 2 Y 2/3 Cl 4 has a wide electrochemical window of 0.59−3.76 V and good interfacial stability with high-voltage cathodes, which ensures its ability to improve the energy density of ASIBs. This study demonstrates the promising application of the spinel framework in sodium solid electrolytes and sheds new light on developing the halide-based solid electrolyte for ASIBs.

Discovery of Superionic Solid-State Electrolyte for Li-Ion Batteries via Machine Learning

“…We recognized that a method of obtaining ionic conductivity at room temperature by extrapolating a result at high temperature could lead to a significant error for some cases. However, since such a method has been widely employed for this type of research, – we strongly believe that current approach is still reliable at least for qualitatively comparing the ionic conductivity values of considered materials.…”

A perspective on the building blocks of a solid-state battery: from solid electrolytes to quantum power harvesting and storage

“…The lowest energy for the E C of Na 3 YCl 6 is 1.62 eV higher than Na 0 ; therefore, Na 3 YCl 6 is supposedly very stable against Na-metal, although with such a reduced electron affinity energy that it may decompose by being reduced from the surface in contact with a reductant. Using DFT simulations, Liu et al 113 proposed a new spinel chloride sodium electrolyte, Na 2 Y 2/3 Cl 4 . This electrolyte is expected to exhibit a high ionic conductivity of 0.94 mS cm −1 at RT with a low activation energy barrier for Na + ion diffusion of 0.29 eV while possessing a semiconductor energy gap 113 from −3.85 to −0.68 eV, E 0 = 0 electrons at rest in a vacuum, E g = 3.17 eV; Fig.…”

“…Using DFT simulations, Liu et al 113 proposed a new spinel chloride sodium electrolyte, Na 2 Y 2/3 Cl 4 . This electrolyte is expected to exhibit a high ionic conductivity of 0.94 mS cm −1 at RT with a low activation energy barrier for Na + ion diffusion of 0.29 eV while possessing a semiconductor energy gap 113 from −3.85 to −0.68 eV, E 0 = 0 electrons at rest in a vacuum, E g = 3.17 eV; Fig. 4 shows the energy concepts.…”

Emerging Halide Solid Electrolytes for Sodium Solid‐State Batteries: Structure, Conductivity, Paradigm of Applications

“…Sun et al reported a new spinel-type chloride, Na 2 Y 2/3 Cl 4 , as a superionic sodium-ion conductor. [82] The spinel skeleton is formed by edge-sharing MCl 6 (M = Na, Y in 16d site) octahedra. Na ions partially occupy the 8a (tetrahedral), 16c (octahedral) and 48f (tetrahedral) sites.…”

“…(f) heat map of calculated mutual reaction energy between solid electrolytes and cathodes. [82] Copyright © 2023, American Chemical Society. stability towards high-voltage cathodes (Figure 12e-f).…”