Understanding the Reactivity of a Thin Li<sub>1.5</sub>Al<sub>0.5</sub>Ge<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> Solid‐State Electrolyte toward Metallic Lithium Anode
Andrea Paolella, Wen Zhu, Gui‐Liang Xu, Andrea La Monaca, Sylvio Savoie, Gabriel Girard, Ashok K. Vijh, Hendrix Demers, Alexis Péréa, Nicolas Delaporte, Abdelbast Guerfi, Xiang Liu, Yang Ren, Cheng‐Jun Sun, Jun Lü, Khalil Amine, Karim Zaghib
Abstract
Abstract The thickness of solid‐state electrolytes (SSEs) significantly affects the energy density and safety performance of all‐solid‐state lithium batteries. However, a sufficient understanding of the reactivity toward lithium metal of ultrathin SSEs (<100 µm) based on NASICON remains lacking. Herein, for the first time, a self‐standing and ultrathin (70 µm) NASICON‐type Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) electrolyte via a scalable solution process is developed, and X‐ray photoelectron spectroscopy reveals that changes in LAGP at the metastable Li–LAGP interface during battery operation is temperature dependent. Severe germanium reduction and decrease in LAGP particle size are detected at the Li–LAGP interface at elevated temperature. Oriented plating of lithium metal on its preferred (110) face occurs during in situ X‐ray diffraction cycling.