Unraveling the superior aqueous Na-ion storage in a multicyano-substituted phenazine-based electrode material

A novel cyano-substituted diquinoxalino-phenazine (CDPZ) organic compound was prepared and integrated with graphene to create a heterostructured electrode material for aqueous Na-ion batteries. With active cyano groups and imino moieties in the CDPZ molecule, the CDPZ@G electrode undergoes highly reversible redox reactions upon Na+ uptake/removal, which is confirmed by electrochemical tests, in situ FTIR analysis and DFT calculations. As a result, the composite electrode achieves superior aqueous Na+ storage with a large specific capacity of ∼265.1 mA h g-1, superior to those of reported organic-based electrodes in alkali-ion aqueous electrolytes.