Ultrastable Cycling in Li_1.5Al_0.5Ge_1.5(PO₄)₃-Based Solid Electrolytes via Pt-Engineered Interfaces

The poor wettability of Na superionic conductor-type Li1.5Al0.5Ge1.5(PO4)3 (LAGP) with lithium metal presents a significant challenge for its application as a solid-state electrolyte in lithium batteries. In this study, a platinum (Pt) interfacial layer is introduced to enhance the wettability of lithium on the LAGP surface, resulting in a significantly reduced LAGP|Li interfacial resistance of 141 Ω·cm2. Symmetric cells incorporating the Pt-coated LAGP demonstrated a high critical current density of 0.6 mA/cm2 and excellent cycling stability, maintaining a low overpotential for over 5000 h at 0.1 mA/cm2 and over 1100 h at 0.4 mA/cm2, all at 25 °C. Furthermore, an all-solid-state lithium–metal battery utilizing NMC as the cathode exhibited a high initial discharge capacity of 150 mA h g–1 at 25 °C, with an outstanding capacity retention of 91% after 100 cycles and a Coulombic efficiency of 97.8%. This work offers a practical and scalable approach to improving the solid-state electrolyte/Li interface, enabling high-performance solid-state batteries.