Graphene oxide wrapped croconic acid disodium salt for sodium ion battery electrodes

Croconic acid disodium salt (CADS), a renewable or recyclable organic compound, is investigated as an anode material in sodium ion battery for the first time. The pristine micro-sized CADS delivers a high capacity of 246.7 mAh g^-1, but it suffers from fast capacity decay during charge/discharge cycles. The detailed investigation reveals that the severe capacity loss is mainly attributed to the pulverization of CADS particles induced by the large volume change during sodiation/desodiation rather than the generally believed dissolution of CADS in the organic electrolyte. Minimizing the particle size can effectively suppress the pulverization, thus improving the cycling stability. Wrapping CADS with graphene oxide by ultrasonic spray pyrolysis can enhance the integration and conductivity of CADS electrodes, thus providing a high capacity of 293 mAh g^-1.