Theoretical Prediction of Spinel Na₂In_xSc_0.666−xCl₄ and Rock‐Salt Na₃In_1−xSc_xCl₆ Superionic Conductors for All‐Solid‐State Sodium‐Ion Batteries

Abstract

The demand for green, clean, and low‐cost energy based on next generation all‐solid‐state batteries is increasing day by day. Compared with all‐solid‐state lithium‐ion batteries, all‐solid‐state sodium‐ion batteries (ASSSIBs) feature better environmental credentials, higher safety, and higher earth abundance. To develop such type of battery system, efficient solid‐state sodium electrolytes with high ionic conductivity at room temperature, wide electrochemical stability window, low electronic conductivity, and interface compatibility are needed, but are rarely reported. In this article, density functional theory and ab initio molecular dynamic simulations are performed to predict new sodium solid electrolytes, which produces a series of sodium superionic conductors with remarkable ion‐conducting properties and interface compatibility. The optimized composition discovered in this work can afford an extraordinary Na‐ionic conductivity of up to 8 mS cm−1 with an extremely low activation energy of 0.20 eV; in addition to the high chemical and electrochemical stabilities, which could be a central idea for the experimental study and accelerate the development of high‐performance ASSSIBs.

Lithium Metal-Compatible Antifluorite Electrolytes for Solid-State Batteries

“…Climbing image nudged elastic band (CI-NEB) calculations were also performed to obtain Li-ion migration barrier energy based on static local-minimum structures. Spin-polarized calculations using the GGA + U method were performed for the relaxation of volume and atomic position in constructing a ternary phase diagram of the Li–N–S system at 0 K. Ab initio molecular dynamic (AIMD) simulations were used with a time step of 2 fs in the canonical (NVT) ensemble for 50 ps for which a 2 × 2 × 2 supercell model for Li 2.5 N 0.5 S 0.5 was used in simulation with a 1 × 1 × 1 k-point grid and a 400 eV energy cutoff in the temperature range of 600–1200 K. A detailed computational method for AIMD and electrochemical window voltage can be seen elsewhere. − …”

Na2FeS2 Cathode for Sodium-Ion Batteries: A Theoretical Study

“…33 Transition metals (Co, V, Ni, and Mn) were substituted at Fe sites to compute volume, bandgap, and hull energy; a detailed theoretical process is reported elsewhere. 34,35 ■…”

“…Climbing image nudged elastic band (CI-NEB) calculations on the basis of static potential energy and AIMD simulations were also carried out to calculate the diffusion barrier energy and thermodynamic stability during Na extraction for Na 2 FeS 2 , Na 1.5 FeS 2 , and NaFeS 2 under the generalized gradient approximation (GGA) . Transition metals (Co, V, Ni, and Mn) were substituted at Fe sites to compute volume, bandgap, and hull energy; a detailed theoretical process is reported elsewhere. , …”

Halide solid-state electrolytes for all-solid-state batteries: structural design, synthesis, environmental stability, interface optimization and challenges

“…39 From another viewpoint, halide fast Li-ion conductors can be generally divided into four categories according to crystalline structures, including (i) trigonal structures (space groups: P 3̄ m 1), such as Li 3 YCl 6 , 33 and Li 3 ErCl 6 ; 40,41 (ii) monoclinic structures (space groups: C 2/ m ), such as Li 3 YBr 6 , 33 Li 3 InCl 6 , 42 and Li 3 ScCl 6 ; 24 (iii) orthorhombic structures (space groups: Pnma ), such as Li 3 YbCl 6 43 and Li 2.5 Y 0.5 Zr 0.5 Cl 6 ; 44 (iv) spinel structures (space groups: Fd 3̄ m ), such as Li 2 Sc 2/3 Cl 4 , 45 Li 2 Sc 2/3− x Er x Cl 4 , 46 and Li 2 FeCl 4 . 47 In parallel, halide fast Na-ion conductors, mainly including Na 2 ZrCl 6 , 48 NaAlCl 4 , 49 Na 3 MCl 6 (M = Y, Er, In, Sc, and Yb), 50–52 Na 3 MBr 6 , 51,53 Na 3 MI 6 (M = Sc, Y, La, and In), 54,55 Na 3− x Y 1− x Zr x Cl 6 , 56,57 Na 3− x Er 1− x Zr x Cl 6 , 58 Na 2 In x Sc 0.666− x Cl 4 , 59 and Na 3 In 1− x Sc x Cl 6 (ref. 59 ) have also been investigated.…”

“…47 In parallel, halide fast Na-ion conductors, mainly including Na 2 ZrCl 6 , 48 NaAlCl 4 , 49 Na 3 MCl 6 (M = Y, Er, In, Sc, and Yb), 50–52 Na 3 MBr 6 , 51,53 Na 3 MI 6 (M = Sc, Y, La, and In), 54,55 Na 3− x Y 1− x Zr x Cl 6 , 56,57 Na 3− x Er 1− x Zr x Cl 6 , 58 Na 2 In x Sc 0.666− x Cl 4 , 59 and Na 3 In 1− x Sc x Cl 6 (ref. 59 ) have also been investigated. However, there is still a large gap between the limited ionic conductivity (<0.1 mS cm −1 ) of halide fast Na-ion conductors and the demand for practical applications.…”