In Situ Composites of Phthalocyanine-Based Covalent Organic Frameworks with Carbon Cloth as a Flexible Binder-Free Anode Material for High-Performance Lithium/Sodium-Ion Batteries

In situ Schiff base reaction is utilized to grow phthalocyanine covalent organic frameworks (TFPB-NiPc) on carbon cloth (CC) to obtain the composite material TFPB-NiPc@CC, which is used as the anode for the binder and conductive agent free Li/Na-ion batteries with enhanced active materials loading. What is more, CC acts as an excellent conductive backbone while reducing the stacking effect of phthalocyanine frameworks (Pc-COFs), which enables TFPB-NiPc to realize the self-exfoliation effect during the in situ synthesis process. This strategy shortens the migration path of Li⁺, efficiently resulting in improving the migration rate of Li⁺ in the electrode. Consequently, the TFPB-NiPc@CC electrode not only shows improved electrochemical behaviors of high capacity and long cycle stability but also displays superior flexibility and folding stability. The specific capacity achieved by the TFPB-NiPc@CC electrode is 1090.2 mA h/g at 200 mA/g, and after 500 cycles, the specific capacity of the TFPB-NiPc@CC electrode can also be maintained at 994.5 mA h/g with a retention ratio of 91.2%, which are all much higher than those of the TFPB-NiPc electrode. Moreover, TFPB-NiPc@CC also shows a high specific capacity and stable cycling behaviors in Na-ion batteries. The strategies designed in this work provide new ideas and methods for preparing practical, high-performance flexible organic anode materials.