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

Li_1.3Al_0.3Ti_1.7(PO₄)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_0.8Co_0.1Mn_0.1]O₂|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.