Sodium storage in triazine-based molecular organic electrodes: The importance of hydroxyl substituents

Rational design and synthesis of novel organic electrodes have captured growing attention for the development of sustainable sodium ion batteries (SIBs), but the battery performance has been significantly limited by poor reversible specific capacity and cycling ability. Here, we report a simple structural modulation approach for creating a new type of triazine compounds as anode materials displaying superior SIB performance. We find that trihydroxyphenyl functionalities conjugated with the triazine ring enhance electrochemical affinities for Na-ion trapping, thereby promoting reversible Na-ion insertion/deinsertion. The resultant trihydroxyl-modulated triazine-based anode exhibits an exceptional battery capacity, reaching as high as 650 mAh g-1 at a current density of 0.1 A g-1 and ranks at the top among all reported molecular SIB electrodes. The simple modulation approach not only enables us to achieve exceptional sodium storage but simultaneously provides a means to extends our understanding of structure-property relationship and facilitate new possibilities for organic SIBs.