Construction of a flexible polymer rechargeable battery based on covalent organic frameworks coated carbon nanotubes...

Entire polymer rechargeable batteries (EPRBs), which utilize organic polymer materials for both electrodes and electrolytes, are garnering increasing attention due to their numerous appealing attributes, such as high-power density and flexible fabrication, among others. As the core of EPRBs, redox-active polymer electrode with high capacity and electronic conductivity are still lacking. Additionally, the compatibility between polymer cathodes and anodes, as well as between electrodes and polymer electrolytes, requires careful optimization. Here, a covalent organic framework containing triazine and ketone groups (TpTt COF) was employed as the polymer anode. To mitigate the stacking of COF layers and enhance electron diffusion kinetics within the electrode, a few-layered TpTt COF encapsulated by carbon nanotube (CNT@TpTt COF) was synthesized using a facile in-situ growth strategy that exploits π-π interactions. Remarkably, upon activation, CNT@TpTt COF demonstrates six-electron redox reaction, achieving a large reversible capacity of 434 mAh g^-1 and superior rate performance. Supported by theoretical calculations and electrochemical behavior analysis, the redox mechanism of CNT@TpTt COF is identified as n-type redox behavior. Furthermore, an innovative dual-ion type EPRB was assembled, featuring an n-type CNT@TpTt COF anode, a p-type polymer cathode, and a solid polymer electrolyte. This EPRB exhibited a discharge capacity of 103 mAh g^-1 and holds potential for flexibility. This work may pave the way to the development of high-performance flexible entire polymer rechargeable batteries.