Design and Synthesis of D‐A Polymer as Cathode Material for Na‐Based Dual‐Ion Batteries with Excellent Cycling Performance

Abstract

AbstractOrganic bipolar electrodes can undergo both n‐type and p‐type reactions for energy storage due to numerous active sites, which can usually deliver a high theoretical specific capacity. Herein, a new bipolar polymer cathode material PQPZ is designed and synthesized. The electron‐donating phenazine group undergoes a two‐electron redox reaction which can store anions, the electron‐withdrawing phenanthraquinone can store sodium‐ions through a two‐electron redox reaction. Notably, as a bipolar cathode material for sodium‐ion batteries, PQPZ exhibits a reversible specific capacity of up to 270 mAh g−1 in the voltage range of 1.0–4.0 V (vs. Na+/Na) and achieves a high energy density of 696 Wh kg−1 in a half‐cell. A capacity retention rate of 90% is obtained after 300 cycles at a current density of 0.5C. More excitingly, even after being cycled for 10000 cycles at 10C, the PQPZ electrode shows an average decay rate as low as 0.0036% per cycle, manifesting a very stable cycling performance. In addition, PQPZ also shows excellent performances when tested at −10 °C, making it promising in practical applications. Considering the bipolar character of PQPZ, symmetric batteries are also successfully constructed, fulfilling the “ready‐to‐charge” property without a pre‐activation process. The results reveal the potential application of PQPZ in practical use.