Sodium- ion batteries have attracted attention in recent times due to sodium is highly abundant and cost effective in comparison to lithium. However the traditional inorganic based electrode materials suffering due to the constraint imposed by their structural aspects and scarcity of resources. Hence researchers focus on alternative electrode materials which could be synthesized from renewable sources via eco-friendly processes [1]. Recently redox active organic materials have gained great interest in energy storage and conversion field, particularly Na-ion batteries due to their structural diversity, eco-friendly processability and resource renewability [2].  In this connection we report imide carboxylate based sodium salts namely, disodium N, N'-bis (glycinyl) pyromellitic diimide (Na₂-BPDI) and disodium N, N'-bis (glycinyl) naphthalene diimide (Na₂-BNDI) as electrode materials for Na-ion batteries for the first time. These compounds are easily synthesizable and most stable at ambient conditions.  Among two compounds Na₂-BNDI delivered a stable reversible capacity of 122 mAh g^-1 at a current density of 50 mA g^-1 (Fig.1), where as a marginal capacity fading was observed upon cycling in the case of Na₂-BPDI.  This capacity fading is due to change in unit cell volume followed by decomposition mechanism involved during the cycling and it is confirmed by ex-situ ¹H NMR, IR and XRD.

References

[1] Haiyan Chen, Michel Armand, Jean-Marie Tarascon and Philippe Poizot, J. AM. CHEM. SOC. 31(2009) 8984–8988.

[2] S. Renault, S. Gottis, A.-L. Barrès, M. Courty, O. Chauvet, F. Dolhem, P. Poizot, Energy Environ. Sci. 6 (2013) 2124-2133