Long‐lifespan Polyanionic Organic Cathodes for Highly Efficient Organic Sodium‐ion Batteries

An organic Na‐ion battery is reported with a polyanionic 9,10‐anthraquinone‐2,6‐disulfonate (Na 2 AQ26DS, 130 mAh g −1 ) cathode and the Na‐intercalated state (Na 4 TP) of sodium terephthalate (Na 2 TP, 255 mAh g −1 ) as the anode. The resulting full cells deliver the maximum discharge capacity of 131 mAh g −1 cathode in 0.5–3.2 V, simultaneously maintaining the average value of ≈62 mAh g −1 cathode during 1200 cycles (0.5 A g −1 , ≈4 C). These results are among the best performing organic sodium‐ion full cells reported to date.