Phenanthraquinone-based polymer organic cathodes for highly efficient Na-ion batteries.

[Display omitted] • A poly(9,10-phenanthraquinone-alt-benzene) (PPQ) cathode is reported. • Characterizations confirm its polymer nature in Na-ion batteries. • In half cells, PPQ shows very stable 150 mAh g−1 during 300 cycles. • In full cells, PPQ delivers average ∼ 126 mAh g−1 during 150 cycles. A new organic polymer cathode namely poly(9,10-phenanthraquinone-alt-benzene) (PPQ, ∼190 mAh g−1) is designed and synthesized for sodium-ion batteries (SIBs). Adequate characterizations are carried out to define its polymer nature. In half cells, the discharge capacity of PPQ shows almost no attenuation, stably maintaining at 150 mAh g−1 during 300 cycles. In full cells, the PPQ II Na 3 Bi SIBs realize the stable discharge capacities of average 126 mAh g−1 cathode during 150 cycles (100 mA g−1 cathode) and average 97 mAh g−1 cathode during 800 cycles (800 mA g−1 cathode), along with the average discharge voltage of ∼ 1.5 V. To the best of our knowledge, the results of PPQ can represent the new advancement for organic polymer cathodes in SIBs. [ABSTRACT FROM AUTHOR]