Alkynyl-Based Covalent Organic Frameworks as High-Performance Anode Materials for Potassium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Organic Chemistry

Background:

• High-performance organic electrodes are crucial for sustainable and cost-effective potassium-ion batteries (KIBs).
• Traditional lithium-ion battery electrolyte systems often show limited success in KIBs.
• Developing novel anode materials is key to advancing KIB technology.

Purpose of the Study:

• To investigate alkynyl-based covalent organic frameworks (COFs) as bulk anode materials for KIBs.
• To evaluate the electrochemical performance of TAEB-COF and DBA-COF in a localized high-concentration electrolyte.
• To understand the potassium-ion binding mechanisms within the COF structures.

Main Methods:

• Synthesis and characterization of two alkynyl-based COFs: 1,3,5-tris(arylethynyl)benzene (TAEB) and dehydrobenzoannulene (DBA).
• Electrochemical testing of COFs as anode materials in KIBs using a localized high-concentration electrolyte.
• Density Functional Theory (DFT) calculations to elucidate ion binding mechanisms.

Main Results:

• TAEB-COF delivered a high reversible capacity of 254.0 mAh g⁻¹ at ~100% efficiency over 300 cycles.
• DBA-COF exhibited a capacity of 76.3 mAh g⁻¹ with 98.7% efficiency after 300 cycles.
• DFT calculations indicated that alkynyl units in TAEB-COF promote K-ion binding via enthalpic and geometric factors.

Conclusions:

• Alkynyl-based COFs, particularly TAEB-COF, show significant promise as high-performance anode materials for KIBs.
• The unique structure of TAEB-COF facilitates efficient potassium-ion storage, leading to high reversible capacities.
• These findings contribute to the development of advanced organic electrode materials for next-generation energy storage devices.