Single-Crystalline Borate Covalent Organic Frameworks for Solid-State Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Lithium metal batteries (LMBs) require advanced solid-state electrolytes for improved safety and performance.
• Covalent Organic Frameworks (COFs) offer tunable properties like porosity, stability, and ion conductivity for electrolyte applications.

Purpose of the Study:

• To synthesize and characterize a novel 3D borate COF (B-COF) as a solid-state electrolyte for LMBs.
• To evaluate the ionic conductivity, ion transport properties, and electrochemical stability of the B-COF.

Main Methods:

• Synthesis of a single-crystalline 3D borate COF.
• Ionic conductivity measurements at room temperature.
• Electrochemical testing in symmetric and full cells with LiFePO4 cathodes.

Main Results:

• The B-COF exhibited high ionic conductivity (8.1 mS cm⁻¹) and an excellent lithium-ion transference number (0.98).
• Stable lithium deposition/stripping for 2000 hours was achieved, suppressing dendrite formation.
• Full cells demonstrated high initial capacity (147 mAh g⁻¹), good retention (91.8%), and high Coulombic efficiency (99.98%) over 600 cycles.

Conclusions:

• The developed B-COF shows significant potential as a high-performance solid electrolyte for advanced lithium metal batteries.
• The material's properties are conducive to enabling uniform lithium deposition and preventing dendrite growth.
• This work contributes to the development of safer and more efficient energy storage solutions.