Adjusting morphological properties of organic electrode material for efficient Sodium-ion batteries by isomers strategy

Abstract

In this work, two isomers are mixed in different proportions and then alkalized as the organic anode material for sodium-ion batteries (SIBs). The mixed material, denoted as PN, shows distinct morphology and electrochemical properties, compared to the single-component Na-CPP and Na-CPN. The Initial Coulombic Efficiency (ICE) value obtained by using the mixed PN as anode is higher than that using the single component. And the capacity retention rate of the mixed PN electrode is 92% after 1200 cycles under 935 mA g−1 high current density. This is mainly due to the superior morphology of the mixed PN electrode (the optimal ratio is CPP: CPN = 3: 1, the mass ratio (or molar ratio)), which exhibits more uniform spherical particles, thus increasing the contact area with the electrolyte and ensuring close contact with the conductive carbon. As a result, the ICE and cycle performance is improved because of the reduced irreversible side reactions. As far as we know, this is the first example of mixing two isomers as organic anode materials in traditional SIBs, and this strategy may provide new insights into future development of organic electrode materials.