Robust MOF-Based Composite Solid-State Electrolyte Membrane for High-Performance Lithium-Metal Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid-state electrolytes (SSEs) are crucial for next-generation lithium batteries, offering enhanced safety and energy density.
• Developing SSEs with a balance of ionic conductivity, mechanical integrity, and electrochemical stability remains a significant challenge.
• Metal-organic frameworks (MOFs) show promise as components in SSEs due to their tunable structures and high surface areas.

Purpose of the Study:

• To fabricate a robust, flexible MOF-based composite membrane for solid-state electrolytes.
• To investigate the synergistic effects of PVDF-HFP, UIO-66 (MOF), and ionic liquid (IL) on electrolyte performance.
• To evaluate the electrochemical and mechanical properties of the developed composite membrane for lithium metal batteries.

Main Methods:

• Construction of a composite membrane using polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), UIO-66 MOF, and an ionic liquid.
• Incorporation of IL within the MOF pores to create continuous ion channels.
• Characterization of ionic conductivity, Li+ transference number, electrochemical window, mechanical properties, and interfacial stability.
• Assembly and testing of LiFePO4//Li batteries using the fabricated SSEs.

Main Results:

• The composite membrane achieved high ionic conductivity (5.55 × 10⁻⁴ S cm⁻¹).
• Excellent mechanical properties were observed, including a tensile strength of 6.63 MPa and 232% elongation.
• The membrane demonstrated good interfacial stability with stable Li plating/stripping and a high Li+ transference number (0.52).
• The assembled LiFePO4//Li battery showed excellent rate capability and cycle stability.

Conclusions:

• The synergistic effect of MOF and IL in the PVDF-HFP matrix leads to superior solid-state electrolyte performance.
• The developed MOF-based composite membrane is a promising candidate for high-performance lithium metal batteries.
• This work presents a viable strategy for fabricating advanced MOF-based composite SSEs.