Ionic Liquid-Impregnated ZIF-8/Polypropylene Solid-like Electrolyte for Dendrite-free Lithium-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Metal-organic framework (MOF)-based solid-like electrolytes offer advantages over traditional liquid electrolytes but face challenges in safety, ionic conductivity, and mechanical strength for lithium-metal batteries.
• Existing MOF electrolytes often rely on organic liquid components, failing to fully address safety concerns associated with lithium-metal batteries.
• Enhancing ionic conductivity and mechanical robustness is crucial for developing practical and safe solid-state battery technologies.

Purpose of the Study:

• To design and develop a novel MOF-based solid-like electrolyte with improved safety and electrochemical performance for lithium-metal batteries.
• To investigate the potential of ionic liquid-impregnated porous membranes with integrated ZIF-8 nanoparticles as advanced solid-like electrolytes.
• To evaluate the electrochemical properties, including ionic conductivity, lithium-ion transference number, and mechanical strength, of the developed electrolyte.

Main Methods:

• Fabrication of an ionic liquid-impregnated polypropylene (PP) porous membrane with uniformly distributed ZIF-8 nanoparticles.
• Characterization of the solid-like electrolyte's ionic conductivity, lithium-ion transference number, mechanical strength, and electrochemical window.
• Assembly and testing of lithium symmetrical cells to assess lithium plating/stripping behavior.
• Fabrication and electrochemical evaluation of LiFePO4/Li full batteries using the developed solid-like electrolyte.

Main Results:

• The developed solid-like electrolyte achieved an ionic conductivity of 2.09 × 10^-4 S cm^-1 at 25 °C and a lithium-ion transference number of 0.45.
• The electrolyte exhibited enhanced mechanical strength, a wider electrochemical window, and superior nanowetted interfaces.
• Lithium symmetrical cells demonstrated stable Li plating/stripping for 550 hours, and LiFePO4/Li full batteries showed excellent rate capability and cycling stability (91.23% retention after 450 cycles).

Conclusions:

• The ionic liquid-impregnated PP membrane with ZIF-8 nanoparticles represents a promising solid-like electrolyte for high-safety lithium-metal batteries.
• This approach effectively addresses safety concerns associated with liquid electrolytes while enhancing key performance metrics.
• The study provides a new pathway for developing advanced MOF-based solid-like electrolytes for next-generation energy storage devices.