High Voltage Flexible Sodium‐Ion Battery Cathode Materials Based on 1D Covalent Organic Framework

Abstract

Abstract Covalent organic frameworks (COFs) have emerged as promising electrode materials for sodium‐ion batteries (SIBs) due to their well‐ordered porous structures that facilitate ion storage and transport. However, conventional 2D and 3D COFs often require post‐processing, such as ball milling or carbon compositing, to enhance electrochemical performance. In this study, a 1D imine‐linked COF, N , N , N ′, N ′‐Tetrakis(4‐aminophenyl)‐1,4‐phenylenediamine‐2,6‐pyridinedicarboxaldehyde (TP‐PDA), is synthesized via a one‐step Schiff base reaction, achieving a fully conjugated and porous structure that enables efficient sodium‐ion transport. TP‐PDA is insoluble in organic electrolytes, ensuring stable cycling performance. The material exhibits a high average discharge potential of 3.1 V and delivers a discharge capacity of 124 mAh g −1 at 3 A g −1 after 1800 cycles, with a capacity retention exceeding 90%. In a full‐cell configuration with a hard carbon anode, the battery maintains a stable capacity of 122 mAh g −1 after 10 000 cycles at 1 A g −1 without noticeable capacity degradation. Furthermore, the flexible pouch cell retains its electrochemical integrity under bending conditions, demonstrating its potential for flexible and wearable energy storage applications.