Sulfonic acid functionalized covalent organic frameworks for lithium-sulfur battery separator and oxygen evolution...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Covalent organic frameworks (COFs) show promise for energy storage and catalysis.
• Lithium-sulfur batteries (LSBs) face challenges with polysulfide shuttle and limited ionic conductivity.
• Oxygen evolution reaction (OER) requires efficient and stable electrocatalysts.

Purpose of the Study:

• To prepare a COF with sulfonic groups (COF-SO3) for modified LSB separators.
• To investigate the electrochemical performance of COF-SO3 in LSBs.
• To explore the application of COF-SO3 as an electrocatalyst for OER.

Main Methods:

• Synthesis of a sulfonic group-containing COF (COF-SO3).
• Fabrication of COF-SO3 modified separators for LSBs.
• Electrocatalytic testing of COF-SO3@FeNi for OER in alkaline electrolyte.

Main Results:

• COF-SO3 separators enhanced ionic conductivity (1.83 mS·cm⁻¹) and suppressed polysulfide shuttle in LSBs.
• LSBs with COF-SO3 separators achieved an initial capacity of 890 mA·h·g⁻¹ at 0.5 C, retaining 631 mA·h·g⁻¹ after 200 cycles.
• COF-SO3@FeNi electrocatalyst exhibited a low OER overpotential (350 mV at 10 mA·cm⁻²) and excellent stability over 1000 cycles.

Conclusions:

• Sulfonic group-modified COFs are effective for improving LSB performance by enhancing ionic conductivity and inhibiting polysulfide migration.
• COF-SO3, when integrated with FeNi, serves as a highly stable and efficient electrocatalyst for OER.
• This work highlights the versatility of COFs in advancing electrochemical applications.