High‐Performance Polyimide Covalent Organic Frameworks for Lithium‐Ion Batteries: Exceptional Stability and Capacity Retention at High Current Densities

Abstract

Organic polymers are considered promising candidates for next‐generation green electrode materials in lithium‐ion batteries (LIBs). However, achieving long cycling stability and capacity retention at high current densities remains a significant challenge due to weak structural stability and low conductivity. In this study, we report the synthesis of two novel polyimide covalent organic frameworks (PI‐COFs), COF‐JLU85 and COF‐JLU86, by combining truxenone‐based triamine and linear acid anhydride through polymerization. These PI‐COFs feature layers with pore channels embedded with 18 carbonyl groups, facilitating rapid lithium‐ion diffusion and enhancing structural stability under high current densities. Compared to previously reported organic polymer materials, COF‐JLU86 demonstrates the excellent performance at high current densities, with an impressive specific capacity of 1161.1 mA h g‐1 at 0.1 A g‐1, and outstanding cycling stability, retaining 1289.8 mA h g at 2 A g‐1 after 1500 cycles and 401.1 mA h g‐1 at 15 A g‐1 after 10000 cycles. Additionally, in‐situ infrared spectroscopy and density functional theory (DFT) calculations provide mechanistic insights, revealing that the high concentration of carbonyl redox‐active sites and the optimized electronic structure contribute to the excellent electrochemical performance.