Anthraquinones with Ionizable Sodium Sulfonate Groups as Renewable Cathode Materials for Sodium‐Ion Batteries

Abstract In this study, the electrochemical performances of anthraquinone (C 14 H 8 O 2 ) without modification, anthraquinone‐1‐sulfonic acid sodium (C 14 H 7 NaO 5 S) and anthraquinone‐1,5‐disulfonic acid disodium salts (C 14 H 6 Na 2 O 8 S 2 ) as organic cathode materials for sodium‐ion batteries are reported for the first time. Ionizable sodium sulfonate functional groups lead to a significant enhancement of the structural stability of C 14 H 8 O 2 , yielding excellent cycle and rate performance. The C 14 H 6 Na 2 O 8 S 2 and C 14 H 7 NaO 5 S electrodes exhibit initial discharge capacities of 195 and 209 mAh g −1 , which are maintained at 131 and 93 mAh g −1 , respectively, after 100 cycles at a current density of 30 mA g −1 . Even at a high rate of 480 mA g −1 , the initial discharge capacity of C 14 H 6 Na 2 O 8 S 2 is 114 mAh g −1 , indicating a high rate capability. Also, the results show that the carbonyl group is the Na + storage location during charge/discharge. Owing to their superior electrochemical performance, these organic cathode materials demonstrate promise for use in environmentally friendly, sustainable sodium‐ion batteries.