In-situ interfacial passivation and self-adaptability synergistically stabilizing all-solid-state lithium metal batteries

The function of solid electrolytes and the composition of solid electrolyte interphase (SEI) are highly significant for inhibiting the growth of Li dendrites. Herein, we report an in-situ interfacial passivation combined with self-adaptability strategy to reinforce Li_0.33La_0.557TiO₃ (LLTO)-based solid-state batteries. Specifically, a functional SEI enriched with LiF/Li₃PO₄ is formed by in-situ electrochemical conversion, which is greatly beneficial to improving interface compatibility and enhancing ion transport. While the polarized dielectric BaTiO₃-polyamic acid (BTO-PAA, BP) film greatly improves the Li-ion transport kinetics and homogenizes the Li deposition. As expected, the resulting electrolyte offers considerable ionic conductivity at room temperature (4.3 × 10⁻⁴ S cm⁻¹) and appreciable electrochemical decomposition voltage (5.23 V) after electrochemical passivation. For Li-LiFePO₄ batteries, it shows a high specific capacity of 153 mA h g⁻¹ at 0.2 C after 100 cycles and a long-term durability of 115 mA h g⁻¹ at 1.0 C after 800 cycles. Additionally, a stable Li plating/stripping can be achieved for more than 900 h at 0.5 mA cm⁻². The stabilization mechanisms are elucidated by ex-situ XRD, ex-situ XPS, and ex-situ FTIR techniques, and the corresponding results reveal that the interfacial passivation combined with polarization effect is an effective strategy for improving the electrochemical performance. The present study provides a deeper insight into the dynamic adjustment of electrode-electrolyte interfacial for solid-state lithium batteries.