Engineering Functionalized 2D Metal-Organic Frameworks Nanosheets with Fast Li⁺ Conduction for Advanced Solid...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Solid-state batteries offer high energy density and safety but face challenges with polymer electrolyte ion transport.
• Metal-organic frameworks (MOFs) are explored as fillers for poly(ethylene oxide) (PEO) electrolytes, yet their functionalization and impact on ion transfer require deeper understanding.
• Existing polymer electrolytes suffer from slow ion kinetics and poor Li+ selectivity.

Purpose of the Study:

• To investigate how functional group regulation in MOFs influences surficial charge distribution and anion movement in solid-state electrolytes.
• To design functionalized 2D MOF sheets for high-performance composite electrolytes.
• To enhance ionic conductivity and mechanical properties of PEO-based electrolytes for improved solid-state battery performance.

Main Methods:

• Computational and experimental approaches were combined to study functionalized MOFs.
• Molecular engineering was used to design functionalized 2D MOF sheets.
• Fabrication of composite electrolytes using functionalized MOFs and PEO.
• Electrochemical testing of Li/Li and LiFePO4/Li cells with the developed composite electrolytes.

Main Results:

• Electron-donating substituents in 2D MOFs effectively limit anion (ClO4-) movement.
• Functionalized MOFs improved mechanical properties and increased ion migration numbers in PEO from 0.36 to 0.64.
• Li/Li cells demonstrated superior cyclability over 1000 hours at 0.2 mA cm-2.
• LiFePO4/Li batteries achieved reversible capacities of 148.8 mAh g-1 after 200 cycles.

Conclusions:

• Functional group electronic effects in MOFs provide a novel strategy for anion confinement in solid-state electrolytes.
• This approach leads to enhanced ionic conductivity and improved battery performance.
• The study presents a feasible direction for developing high-performance, safe solid-state batteries.