High-Performance Polyimide Covalent Organic Frameworks for Lithium-Ion Batteries: Exceptional Stability and Capacity...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Organic polymers are promising green electrode materials for lithium-ion batteries (LIBs).
• Key challenges include poor structural stability and low conductivity, limiting performance at high current densities.
• Achieving long cycling stability and capacity retention remains a significant hurdle.

Purpose of the Study:

• To synthesize and characterize novel polyimide covalent organic frameworks (PI-COFs) for LIB applications.
• To investigate the electrochemical performance of PI-COFs, particularly their stability and capacity retention at high current densities.
• To elucidate the mechanisms underlying the enhanced electrochemical performance.

Main Methods:

• Synthesis of polyimide covalent organic frameworks (PI-COFs) via polymerization of truxenone-based triamine and linear acid anhydride.
• Electrochemical performance evaluation, including specific capacity and cycling stability at various current densities (0.1 to 15 A/g).
• In situ infrared spectroscopy and density functional theory (DFT) calculations for mechanistic insights.

Main Results:

• Two novel PI-COFs, COF-JLU85 and COF-JLU86, were successfully synthesized.
• COF-JLU86 exhibited excellent performance: 1161.1 mAh/g at 0.1 A/g, 1289.8 mAh/g at 2 A/g (1500 cycles), and 401.1 mAh/g at 15 A/g (10000 cycles).
• High concentration of carbonyl redox-active sites and optimized electronic structure were identified as key contributors to performance.

Conclusions:

• PI-COFs demonstrate superior electrochemical performance compared to existing organic polymer materials for LIBs.
• The designed PI-COFs effectively address challenges of structural stability and conductivity at high current densities.
• These findings highlight PI-COFs as a promising class of high-performance organic electrode materials for advanced LIBs.