Double-Faced Bond Coupling to Induce an Ultrastable Lithium/Li₆PS₅Cl Interface for High-Performance All-Solid-State Batteries

Sulfide-type solid electrolytes (SSEs) are supposed to be preferential candidates for all-solid-state Li metal batteries (ASSLMBs) due to their satisfactory Li+ conductivity and preferable mechanical stiffness. Nonetheless, the poor stability between the Li anode and SSEs and uncontrolled Li dendrite growth severely restrict their commercial application. Herein, an amphiphilic LixSiOy-enriched solid electrolyte interphase (SEI) as a “Janus” layer was first introduced at the Li/SSEs interface, and it exhibited bond coupling reactivity with both the Li anode and SSEs by forming Li–S, Li–O–Si, and Si–S covalent bonds, which is called the pincer effect. In addition to the physical isolation of Li and SSEs to prevent side reactions between them, LixSiOy with high ionic conductivity offers abundant and evenly distributed transport channels for fast Li+ migration. As evidenced by in situ microscopy, the high-strength anodic interface constructed by the pincer effect and in situ decomposition mentioned above is free from mechanical damage during the Li plating/stripping. As a result, the symmetric cells exert an outstanding cycling performance for over 2000 h at 0.2 mA cm–2 and even 500 h at 0.5 mA cm–2 without evident resistance growth. The artificial SEI layer with the pincer effect and its effective application in interfacial stabilization put forward a new perspective for the commercialization of ASSLMBs.