Polymer organic cathodes enable efficient desolvation for highly stable sodium-ion batteries

A novel organic polymer cathode namely poly(anthraquinone-alt-benzene) (PAQB, ∼190 mAh g−1) is intentionally designed and synthesized for sodium-ion batteries (SIBs). Full characterizations are carried out to define its polymer nature. Due to the strong π-π interaction of polymer main chains, the insoluble PAQB solid exhibits very efficient desolvation process against the solvated Na+ ions in liquid electrolytes when compared to its insoluble dimer analogue (BAQB), leading to its highly impressive cycle stability and long material life. In half cells, PAQB can realize an average discharge capacity of 128 mAh g−1 during the ultra-long lifespan over 1 year. In the full cells with Na3Bi anode, the resulting PAQB II Na3Bi SIBs can realize the peak discharge capacity of 172 mAh g−1cathode and stably hold 160 mAh g−1cathode after 1000 cycles at 200 mA g−1. To the best of our knowledge, PAQB is among the top cathodes currently reported for SIBs. And this work forwards a significant step for the application of organic electrodes in SIBs.