ZnO Substitution in Argyrodite Li5.5+3xZnxP1‐xOxS4.5‐xBr1.5 Electrolyte with Enhanced Interface Performance for All‐Solid‐State Battery

Abstract Argyrodite sulfide solid electrolytes (SSEs) have been attracting more concentration in ionic conductivity, crystal structure, and mechanical properties. Nevertheless, shortcomings of SSEs like poor air‐vapor stability and interface reactions limit the wider application in batteries. Herein, a double‐element ZnO substitution strategy is applied to enhancing Li 5.5 PS 4.5 Br 1.5 Argyrodite electrolyte structure stability and property, Li 5.5 PS 4.5 Br 1.5 electrolyte with a small amount of ZnO substitution to P and S. Li 5.5+3x Zn x P 1‐x O x S 4.5‐x Br 1.5 solid electrolytes have achieved improved performance, interface composition also has changed, and crystal structure is becoming more stable. Specifically, LPSBr 1.5 ‐4 %ZnO exhibits the most promising comprehensive properties, more expanded lithium pathway and crystal cell size, 2.25 mS cm −1 ionic conductivity at 25 °C, 65 % electronic conductivity decline, and air stability enhancement. Moreover, LPSBr 1.5 ‐4 %ZnO show decent lithium compatibility and dendrite suppression capability, LPSBr 1.5 ‐4 %ZnO can continue cycling for more than 800 h at 0.1 mA cm −2 in Li symmetric cell, and critical current density has reached 1.4 mA cm −2 . More importantly, an all‐solid‐state battery (ASSB) with LPSBr 1.5 ‐4 %ZnO electrolyte can cycle with 130 mAh g −1 capacity and more than 120 cycles in LiCoO 2 |SSE|In‐Li cell. Our work might provide a strategy to promote structure stability and electrochemical durability, and how element substitution affects ionic transport pathway and crystal structure.