Dual-Bipolar Conjugated Organic Polymer Cathode Enabling Ultra-Stable 10 000-Cycle Organic Lithium and Sodium...

Organic molecules are potential electrode materials for various rechargeable batteries owing to their designable molecular structures and renewable resources; however, their poor electronic conductivity and high solubility in electrolytes limit their electrochemical performance. These challenges can be addressed by constructing conjugated organic polymers (COPs). Herein, a dual-bipolar centers COP is reported via polymerization of 5,15-bis(4-cyanophenyl) porphyrin (H₂BCPP) using triazine linker (H₂BCPP-COP) and evaluate its performance as a cathode for both lithium and sodium batteries. The electrochemical performance of H₂BCPP-COP is significantly improved compared with H₂BCPP in both systems, exhibiting high capacity, outstanding rate capability, and excellent cycling stability. Notably, in organic lithium batteries (OLBs), H₂BCPP-COP achieves a capacity of 121 mAh g^-1 over 10 000 cycles with 89% capacity retention of maximum capacity at 2.0 A g^-1 at room temperature, while maintaining stable operation across a wide temperature range (-20-50 °C). Even higher capacities are observed in organic sodium batteries (OSBs), highlighting their versatility. In/ex situ spectroscopic analyses and theoretical simulations reveal that the exceptional performance arises from the highly stable COP backbone and the alternating interaction of cations and anions with the dual-bipolar active sites (C─N/C═N) in the porphyrin and triazine units.