Stability of organic Na-ion battery electrode materials: The case of disodium pyromellitic diimidate

• A new organic Na-battery electrode material is synthesized.
• Batteries show acceptable capacity during 100 cycles.
• The capacity decrease can be explained by decomposition reactions.

A novel organic Na-salt is presented here for utilization as an active electrode material in rechargeable Na-ion batteries. The compound, disodium pyromellitic diimidate, is synthesized through a reaction by pyromellitic acid and sodium hydride and characterized using 1H-NMR. Na-batteries of the organic compound were able to obtain capacity values close to the theoretical during the first cycles, but a steady capacity decrease could be observed during cycling. The battery nevertheless delivered a capacity of ca 90 mAh/g after 100 cycles, rendering it a comparatively competitive organic Na-battery material. However, the results stress the importance of tailoring Na-compounds with a good chemical stability also at high levels of sodiation, since decomposition side-reactions can be probable.