Amorphous Multianion Electrolytes with High Stability at Electrolyte-Electrode Interfaces for Solid-State Lithium Batteries.

Achieving solid-state electrolytes (SEs) with both high ionic conductivity and excellent chemical/mechanical compatibility with a Li-metal anode remains a critical challenge for advancing solid-state batteries (SSBs). Crystalline chloride-based electrolytes have shown promising ionic transport properties. However, their performance depends on controlled crystallization processes and defect concentration. Amorphous electrolytes provide an alternative design strategy, enabling grain-boundary-free structures, improved interfacial contact, and Li-ion transport. Here, we introduced an amorphous triple-anion solid-state electrolyte, Li1+yZrCl4N0.33Fy (0 ≤ y ≤ 0.5), achieving a high ionic conductivity of 3.2 mS cm-1 at 25 °C. Nitrogen induces structural disorder in the bulk electrolyte framework, while fluorine enhances interfacial stability with Li metal by forming a LiF-rich passivation layer, reducing the need for sulfur-based protective interlayers. The amorphous Li1+yZrCl4N0.33Fy electrolyte with an NMC811-based cathode and Li-In anode delivers a specific capacity of 200 mAh g-1 at 0.1 C. This amorphous triple-anion electrolyte provides a promising sulfur-free protective interfacial strategy for high-performance solid-state batteries.