Boosting the energy density of organic cathode materials by designing planarized conjugated p-type polymer with multi-redox-active centers

Abstract

P-type organic materials with high redox potential are promising electrode materials for next-generation rechargeable batteries with high-energy–density. Unfortunately, most of the reported p-type materials still deliver limited specific capacity because of their single-redox-active center, low electronic conductivity and sluggish diffusion kinetics of the large anions, resulting in the low material utilization. Herein, we design and successfully synthesize two p-type dihydrophenazine-based organic polymer cathodes (DPZPC and DPZPA), both with multi-redox-active centers, for sodium-organic batteries. Substantial characterizations indicate that the DPZPC with planarized conjugated repeat units exhibits better electronic conductivity, higher surface area, and more ordered microporous structure along with enhanced ionic transportation. As a result, the batteries assembled with DPZPC delivery superior performance with a high specific capacity of 184 mAh g−1 at a current density of 100 mA g−1, a long cycling stability (a capacity retention of 92 % after 100 cycles), and a high rate capability (117 mAh g−1 at 500 mA g−1) in sodium-organic batteries. This work provides a new molecular structure design strategy for organic electrode materials toward high performance rechargeable metal–organic batteries.