Reversible Sodium Storage Behavior of Aromatic Diimide Disodium Carboxylates

Abstract

The synthesis, characterization and electrochemical sodiation/desodiation performance of two novel disodium diimide carboxylates, disodium salt of N,N'-bis (glycinyl) pyromellitic diimide (Na 2 -BPDI) and disodium salt of N,N'-bis (glycinyl) naphthalene diimide (Na 2 -BNDI) were reported for the first time. The Na 2 -BNDI electrode material delivers a reversible capacity of 122 mAh g −1 in the first cycle and retains a reasonable capacity of 92 mAh g −1 after 50 cycles at a current density of 50 mA g −1 , whereas a rapid capacity fading is observed in the case of Na 2 -BPDI electrode material in subsequent cycles. Ex-situ NMR and FT-IR studies confirmed that the decomposition of Na 2 -BPDI electrode material upon continuous electrochemical sodiation/desodiation process. These results demonstrate that the importance of extended conjugation, as in Na 2 -BNDI, for efficient electrochemical sodium storage in the redox active aromatic compound.