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 (Na2 AQ26DS, 130 mAh g-1 ) cathode and the Na-intercalated state (Na4 TP) of sodium terephthalate (Na2 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.