Interfacial optimization of Li1.3Al0.3Ti1.7(PO4)3 based solid-state electrolyte by in-situ thermal polymerization for high reliability lithium metal batteries

The interface issues between solid-state electrolytes and electrodes severely hamper the development of solid-state lithium metal batteries. Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is a competitive candidate among solid-state electrolytes due to its high ionic conductivity, air stability and low-cost. Nevertheless, the poor contact at electrolyte/electrode surface as well as the incompatibility between LATP and lithium metal obstruct its practical application. Herein, a buffer layer is designed on both sides of LATP to improve the interfacial contact and inhibit the side reaction occurs at the surface of Li anode. The in-situ formed interphase is a network structure composed of methyl methacrylate (MMA) and tetraethylene glycol dimethacrylate (TEGDMA), which can be triggered by thermal polymerization. The optimized interface enables continuous migration of lithium ions, thereby facilitating the dynamics of cations across the electrolyte and electrode interface. By this modification, the Li||Li symmetric cells assembled by the final product demonstrate high plating/stripping reversibility, and the Li||LiFePO₄ cells can deliver a discharge capacity of 161 mAh g⁻¹ at 0.1 C. This study proposes a promising strategy for interfacial design and heralds an encouraging prospect for inorganic solid-state electrolytes in reliable utilization.