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Sulfide all-solid-state lithium metal batteries have received increasing attention owing to their high specific energy density and remarkable safety. However, serious interfacial problems still limit their further development. To solve the problem of instability of the interface between the solid-state electrolyte argyrodite (Li6PS5Cl) and lithium anode, strategies such as introducing an alloy cathode, introducing an intermediate interface layer, and directly modifying the electrolyte have been proposed; however, these methods are not suitable for practical applications. Notably, lithium lanthanum zirconium oxide (LLZTO) exhibits high lithium-ion conductivity and remarkable material stability, and silver (Ag) metal shows satisfactory lithium conductivity. Accordingly, a composite interface layer made of LLZTO and Ag was innovatively proposed to solve the lithium metal anode/Li6PS5Cl interface problem and increase the cycle stability of all-solid-state lithium batteries. We studied the effects of LLZTO–Ag composite interface layers with different combination manners, such as simply dispersed LLZTO–Ag composite, evenly dispersed and coated composite, and ball-milled composite, on the anode interface of Li6PS5Cl all-solid-state lithium metal batteries. The electrochemical performance of an optimized all-solid-state battery was also investigated. The results show that the surface of the LLZTO@Ag composite layer obtained by ball milling is relatively smoother and denser, which can effectively prevent lithium dendrite growth and battery short circuit. Compared with the simply dispersed LLZTO–Ag composite method and the evenly dispersed and coated composite method, the ball-milled composite layer anode method can be used to effectively reduce local lithium deposition current density and successfully solve the short circuit problem of the sulfide solid electrolyte. The first cycle efficiency of the LLZTOpw@Agpw–Lipl all-solid-state battery is 77.5%, and the discharge specific capacity is 187.3 mA·h·g−1. After 100 cycles at 0.3C, the discharge specific capacity is still 125.5 mA·h·g−1, and the capacity retention rate is 81.7%. Additionally, we investigated the electrochemical behavior of all-solid-state lithium metal batteries upon the introduction of the LLZTO–Ag composite interfacial layer by using the AC impedance (EIS) and constant-current intermittent titration technique. The LLZTOpw@Agpw anode shows satisfactory cycle stability for lithium batteries. The impedance of the LLZTOpw@Agpw–Lipl all-solid-state battery exhibits periodic oscillations, indicating that lithium vacancies will be generated in the NCM811 crystal upon extraction of lithium ions, thereby increasing the conductivity of the lithium ions and reducing their migration resistance as well. The effect is most prominent when half of the lithium ions are extracted, but further extraction of lithium ions will lead to too many vacancies in the material, following which extraction of lithium ions will be impeded, thereby increasing the migration resistance of the lithium ions. The interfacial impedance on the cathode side considerably increased during long cycling, thus affecting the subsequent cycling performance, while the interface on the anode side remained essentially stable, highlighting the stabilizing effect of the LLZTO–Ag composite interfacial layer.

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Solid state lithium battery is expected to be one of the next generation of battery systems with high energy density in the field of high energy. Based on the constructure characteristics and related formation mechanism of interface between solid polymer electrolyte and lithium anode, the impact of interface contact, interface chemistry and electrochemical reaction, and moreover, the growing process of lithium dendrite and other problems on the interface stability and compatibility were systematically discussed in this review.Thus, the application of doping modification, structure design, and other methods for the interfaces between polymer matrix and lithium anode were also emphasized. In addition, the common interface characterization methods and their applications on the interface between solid polymer electrolyte and lithium anode were also reviewed. Finally, based on the relevant strategies of designing and constructing a stable polymer solid electrolyte-lithium anode interface, the development prospects of interface optimization methods such as doping and core layer design were analyzed and prospected in this paper.

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)