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The sulfide‐type solid electrolyte (SSE) is considered a promising candidate for solid‐state lithium metal batteries (SSLMBs) owing to its advantages of superior ionic conductivity. Nevertheless, the incompatibility of the sulfide and lithium metal can result in undesirable interface resistance and rapid Li dendrite growth, which seriously hinders its commercial applications. Herein, inspired by the moderation and long duration of sustained release drug carriers when combined with active pharmaceutical ingredients in the biomedical field, poly (propylene carbonate) (PPC) and lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) gradually interact with a Li anode with constantly decreased Li/SSE interfacial resistance. In addition to intimate contact, the ultrastable LiF‐enriched solid electrolyte interphase (SEI) is in situ formed via a sustained release effect, which suppresses the Li dendrite effectively. As a result, the symmetric cells demonstrate stable cycling performance for 1200 h at a current density of 0.1 mA cm−2 and 300 h at 0.5 mA cm−2. Moreover, LiFePO4/ Li6PS5Cl /Li SSLMB delivers a high discharge capacity of over 132.8 mAh g−1 for 900 cycles at 1C with steady Coulombic efficiency. Therefore, this sustained release mechanism and its initially successful application in interfacial modification increase the potential for commercial applications of SSLMBs. [ABSTRACT FROM AUTHOR]

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 Li x SiO y -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, Li x SiO y 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.