A Quasi-Solid-State Electrolyte with Semi-Immobilized Solvent-Like Sites for Lithium-Metal Batteries

Abstract

Quasi solid-state lithium-metal batteries (QSSLMBs) hold significant promise for enhanced energy density when compared to conventional battery systems. Nevertheless, current QSSLMBs face challenges in lithium dendrites and electrode-electrolyte interfacial side reactions driven by excessive active free solvent molecules. Herein, a metal-organic framework (MOF) with chemically grafted soft multi-ether molecules (D-Gluconic acid,2,4:3,5-di-O-methylene-, denoted as G) has been proposed to serve as a solid-state electrolyte (SSE). The as-obtained MOF-G-based electrolyte (MGE) comprises structured MOF channels with semi-immobilized solvent-like sites (G molecules), which replace liquid molecules to coordinate with Li⁺ ions. The MGE reduces the demand for solvents compared with traditional QSSEs, thus suppressing interface side reactions. This arrangement also facilitates achieving an elevated Li⁺ transference number (0.64) and a broad electrochemical stability window (5.4 V). Ultimately, the solid-state Li//Li symmetrical battery displays an extended lifetime surpassing 1500 h under 1 mA cm⁻². The solid-state LiFePO4//Li battery utilizing the flame retarded MGE attains an impressive capacity retention of 95.75% over 600 cycles. The MOF-based functionalization strategy introduces an innovative approach to designing high-performance SSE for the advanced solid-state LMBs.

• Download figure
• Download PowerPoint