Benzenediacrylates as organic battery electrode materials : Na versus Li

This paper discusses investigations of a novel Na-based organic battery electrode material, disodium benzenediacrylate (Na(2)BDA) in comparison with its Li-ion homologue. Li(2)BDA has previously shown promising battery properties, such as stable cycling and good capacity retention. Na(2)BDA and Li(2)BDA are here successfully synthesized and characterized, and investigated as anode materials in prototype Na- and Li-ion battery cells. Moreover, different electrolytes are screened for the Na-battery material, and a useful operating voltage window is explored. Na(2)BDA is shown to possess a higher initial coulombic efficiency (91%) than the Li-homologue, which is uncommon for sodiated organic electrode materials. The Na-compound shows an initial capacity of 177.7 mA h g(-1), which however decreases to ca. 50 mA h g(-1) after 20-100 cycles depending on the cycling rate; a significantly lower capacity retention then that observed for Li(2)BDA. The capacity loss can primarily be explained by a decomposition mechanism of the Na(2)BDA compound