Electro‐Chemo‐Mechanical Design of Buffer Layer Enhances Electrochemical Performance of All‐Solid‐State Lithium Batteries

Abstract Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) is a cost‐effective representative solid‐state electrolyte (SSE) with high ionic conductivity and has gradually become a hotspot for all‐solid‐state lithium metal batteries (ASLMBs). Nevertheless, its practicalization has been challenged by the intertwined electro‐chemo‐mechanical interface issues of Li/SSE, such as penetration of Li dendrites, poor physical contact, and poor interfacial compatibility. Thus, it is essential to design interfacial management from an electro‐chemo‐mechanical perspective to guarantee the stability of Li/SSE interface bottom‐to‐up and prolong the cyclic life of ASLMBs with higher electrochemical performance. Here, an electro‐chemo‐mechanical buffer layer with softer mechanics and higher ionic conductivity is constructed on LATP surface by the spontaneous reaction between Li metal and an as‐prepared Ti‐LiF thin film using the magnetron sputtering. Introducing an electro‐chemo‐mechanical buffer layer fosters cross‐interfacial migration of Li‐ions and dissipates interface stress from the growth of Li metal to suppress the early failure of the SSE, realizing long‐term interfacial stability. In consequence, Li[Ni 0.8 Co 0.1 Mn 0.1 ]O 2 |Ti‐LiF LATP|Li ASLMBs deliver a high specific capacity of 163.1 mAh g −1 at 0.2 C, with a capacity retention ratio of 96.1% after 150 cycles. Therefore, the interfacial design from electro‐chemo‐mechanics has been proposed innovatively to open‐up a broad avenue for applying ASLMBs to next‐generation energy storage systems.