Sodium-ion batteries now become a strong alternative candidate for lithium-ion batteries due to abundant Na resources, and organic electrode active materials for sodium-ion batteries also have possibility to bring additional cost reduction. Although many organic-based active materials have been researched as cathode materials for lithium-ion batteries, few works have been conducted for sodium-ion batteries. In this study, the cathode properties of several organic compounds of sodium rhodizonate analogs, Na2CxOx [x = 4 and 5] and K2C6O6 were newly investigated. Among them, it was revealed that Na2C5O5 and Na2C6O6 deliver large first discharge capacity close to 200 mAh g-1 and exhibit reversible sodium insertion/de-insertion of 1.35 and 1.25Na, respectively, with good cycle performance.
Keywords: sodium-ion battery, organic material, sodium oxocarbon salt