Covalent-Organic-Framework Enabled Efficient Three-dimensional K-storage via Electrolyte Solvation Manipulation.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Covalent-organic frameworks (COFs) show promise as anode materials for potassium ion batteries (PIBs).
• Existing COF materials face challenges including low capacity, poor rate performance, and slow kinetics.
• These limitations hinder the widespread application of COFs in efficient K-storage.

Purpose of the Study:

• To develop a novel 3D COF material (CN-COF) for efficient potassium ion battery anodes.
• To enhance interfacial stability and reaction kinetics through electrolyte chemistry compatibility.
• To investigate the synergistic effects of nanostructure design and electrolyte chemistry on K-storage mechanisms.

Main Methods:

• Synthesized a three-dimensional (3D) COF material (CN-COF) with high nitrogen content and graphite-like layer stacking.
• Employed an electrolyte chemistry compatibility strategy using an optimized high-concentration THF-based electrolyte (HTE).
• Characterized the formation of a uniform and stable solid-electrolyte interphase (SEI) with rich inorganic components.

Main Results:

• The CN-COF material delivered a high reversible capacity of 385.8 mAh/g at 50 mA/g.
• Maintained a capacity of 95.3 mAh/g after 1500 cycles at 500 mA/g, demonstrating excellent cycling stability.
• Achieved rapid diffusion kinetics and enhanced interfacial stability due to the optimized SEI layer.

Conclusions:

• The developed CN-COF material, in conjunction with the optimized HTE, significantly improves potassium ion battery anode performance.
• The study demonstrates a viable strategy for designing advanced K-storage materials by combining nanostructure engineering and electrolyte optimization.
• This work offers insights into manipulating K-storage mechanisms for next-generation energy storage solutions.