Fluoroether Design Enables High‐Voltage All‐Solid‐State Lithium Metal Batteries

Developing high-voltage all-solid-state lithium metal batteries (ASSLMBs) holds transformative potential for next-generation energy storage technologies but remains a formidable challenge. Herein, a new prototype design is presented that integrates fluorinated ether segments into the traditional oxide nanocomposite phase, enabling poly(ethylene oxide)-based composite electrolytes with exceptional anti-oxidation durability and enhance overall electrochemical performance. Through a combination of experimental and computational analyses, it is demonstrated that the superior performance is attributed to the formation of reconstructed Li⁺ solvation with weakly coordinating environments. The proposed formulation exhibits excellent Li-metal compatibility, enabling stable cycling in symmetric Li||Li cells for over 9500 h. The solid-state electrolyte also exhibits outstanding high-voltage stability with LiNi_0.8Co_0.1Mn_0.1O₂ cathodes, extending the operational voltage from 4.0 to 4.5 V. Moreover, the LiMn_1-xFe_xPO₄||Li cells have delivered remarkable cycling performance, achieving over 1200 cycles with 99% capacity retention after 500 cycles. This work establishes an innovative platform for designing electrolytes with superior antioxidation properties and enhance structural durability, paving the way for the advancement of high-voltage all-solid-state lithium metal batteries.