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The crucial role of oxygen substitution in argyrodite solid electrolytes from the bulk to the surface under atmospheric conditions
Ist Teil von
Journal of materials chemistry. A, Materials for energy and sustainability, 2022-08, Vol.1 (32), p.1698-16919
Ort / Verlag
Cambridge: Royal Society of Chemistry
Erscheinungsjahr
2022
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Argyrodite-type sulfide-based solid electrolytes (SEs) have drawn immense interest because of their high ionic conductivity. In contrast, the poor structural and electrochemical stabilities of argyrodite-type SEs have recently emerged as a major issue. Based on the combined method of first principles calculations and electrochemical experiments, here, we present Li
6
PO
x
S
5−
x
Br
0.5
Cl
0.5
(
x
= 0, 0.5) SEs and the oxygen (O) substitution mechanism from the surface to the bulk to improve the stability of sulfide-based Li argyrodite SEs, whose surfaces are vulnerable to air exposure. Using first principles calculations, we analyzed the mechanism of the introduction of O substituted for sulfur (S) depending on the different S sites and confirmed the improvement in the stability by calculating the atomic and electronic structures according to the O content for the bulk and the surface models. In particular, we confirmed that variations in the electronic structures of S on the surface and the changed electrochemical environment could facilitate the side reactions, which were suppressed by O introduction. In addition, these designed models were synthesized to verify the calculation results. Electrochemical experiments revealed the structural decomposition and O penetration depending on the depth from the surface to the bulk are suppressed by O introduction. Moreover, introducing O into Li
6
PO
0.5
S
4.5
Br
0.5
Cl
0.5
maintained the ionic conductivity sufficiently, and the conductivity retention after air exposure for a day was notably enhanced compared with that of the pristine Li
6
PS
5
Br
0.5
Cl
0.5
. These improved structural and electrochemical stabilities achieved by introducing O can enhance the electrochemical performances. This study provides a rational strategy for developing promising oxysulfide-based SEs for all-solid-state batteries.
O substitution for S in argyrodite-type sulfide-based solid electrolytes enhances the stability by suppressing reaction with H
2
O and decomposition. O substitution modulates the electronic structures and then improves electrochemical performance.