Sb‐ and O‐Cosubstituted Li₁₀SnP₂S₁₂ with High Electrochemical and Air Stability for All‐Solid‐State Lithium Batteries

Abstract

The development of solid‐state electrolytes with high ionic conductivity, broad electrochemical stability, and high air stability is the key to realizing the practical application of all‐solid‐state batteries. Herein, Sb‐ and O‐cosubstituted Li10SnP2S12 sulfide electrolytes are prepared for the first time. An appropriate amount of Sb and O substitution provides the optimized Li10SnP1.84Sb0.16S11.6O0.4 electrolyte with the highest ionic conductivity of 2.58 mS ⋅ cm−1 at RT. Furthermore, the cyclic voltammetry analysis results demonstrate that the Li10SnP1.84Sb0.16S11.6O0.4 electrolyte displays a broader electrochemical window of 1.4–5.0 V vs. Li+/Li than that of 1.7–2.4 V vs. Li+/Li for the nonsubstituted Li10SnP2S12. Moreover, benefitting from the soft acid Sb5+ and hard base O2− dual substitution, the air stability of electrolyte has been improved. Furthermore, the LiNbO3@LiCoO2/Li−In cell assembled with the Li10SnP1.84Sb0.16S11.6O0.4 electrolytes exhibits a high initial discharge specific capacity of 124.7 mAh ⋅ g−1 at 0.05 C and maintains 85 % capacity retention after 200 cycles at 0.5 C and 25 °C, which is much higher than that of the cell assembled with the Li10SnP2S12 electrolytes. XPS measurement results revealed that the mechanism of improving cell stability is the inhibition of electrolyte side reaction in the cathode. Sb‐ and O‐cosubstituted Li10SnP2S12 was demonstrated to be a promising solid electrolyte for practical all‐solid‐state batteries.

Investigating the Li+substructure and ionic transport in Li10GeP2−xSbxS12(0 ≤x≤ 0.25)

“…The reported Raman signals for the (SbS 4 ) 3− symmetric vibrations range in between 360 cm −1 to 368 cm −1 , 12,41,42 and for the asymmetric stretching mode at 389 cm −1 and 410 cm −1 or 421 cm −1 . 24,41,42 Thus, the occurring peak should be the asymmetric stretch of the (SbS 4 ) 3− unit suggesting that the symmetric stretch of the (SbS 4 ) 3− unit is hidden beneath the symmetric stretch of the (GeS 4 ) 4− unit. To summarize, the Raman indicates that the bond strength of the (PS 4 ) 3− unit is not influenced due to the similarity of the observed wavenumbers for every composition.…”

“…19 Gao et al found an increase in unit cell volume by co-substituting Li 10 SnP 2 S 12 with Sb and O, achieving the highest conductivity of 2.58 mS cm −1 for Li 10 SnP 1.84 Sb 0.16 S 11.6 O 0.4 . 24 The introduction of oxygen led to a blue shift of the (SnS 4 ) 4− and (PS 4 ) 3− vibrational energies, and an additional signal at 421 cm −1 in the Raman spectrum, which is attributed to the (SbS 4 ) 3− unit. 24 Wang et al found that the solubility limit of antimony in the substitution series Li 10 SnP 2− x Sb x S 12 is x (Sb) = 0.2, and that the antimony substitution does not affect the vibrations of (SnS 4 ) 4− and (PS 4 ) 3− in the Raman spectra.…”

“…24 The introduction of oxygen led to a blue shift of the (SnS 4 ) 4− and (PS 4 ) 3− vibrational energies, and an additional signal at 421 cm −1 in the Raman spectrum, which is attributed to the (SbS 4 ) 3− unit. 24 Wang et al found that the solubility limit of antimony in the substitution series Li 10 SnP 2− x Sb x S 12 is x (Sb) = 0.2, and that the antimony substitution does not affect the vibrations of (SnS 4 ) 4− and (PS 4 ) 3− in the Raman spectra. However, the broadening of the unit cell has been suggested to be beneficial for ionic conductivity reaching a maximum of 2.43 mS cm −1 for Li 10 SnP 1.8 Sb 0.2 S 12 .…”

Review of the Developments and Difficulties in Inorganic Solid-State Electrolytes

“…Liu et al prepared a series of Li 10 Sn 0.95 P 2 S 11.9−x O x (0 ≤ x ≤ 1) by the solid-phase sintering method and Li 10 Sn 0.95 P 2 S 11.4 O 0.5 shows high conductivity of 3.96 × 10 −3 S·cm −1 with a negligible decrease after exposed in the air [ 172 ]. Gao et al were first to prepare Sb 5+ and O 2− substituted Li 10 SnP 2 S 12 with high air stability due to the soft acid Sb 5+ and hard base O 2− dual substitution [ 173 ]. The Li 10 SnP 1.84 Sb 0.16 S 11.6 O 0.4 electrolyte displays a broader electrochemical window of 1.4–5.0 V vs. Li + /Li and ionic conductivity of 2.58 × 10 −3 S·cm −1 .…”

Entropy and Isokinetic Temperature in Fast Ion Transport

“…[17] Figure 5 shows other examples from the literature. [55][56][57][58][59][60][61][62][63][64][65] Figure 5a shows the isokinetic prefactor 𝜎 00 as a function of the reciprocal of isokinetic temperature T iso for some perovskitetype proton conductors. Neutron scattering experiments have also confirmed that for perovskite proton conductors, the proton jump time follows a polaron model.…”