Core@shell Bi2S3@Bi2O3 composites with custard apple seed-derived carbon as a high-performance anode material for sodium-ion batteries

Abstract

Enhancement of the electrochemical performance of Bi₂O₃ and Bi₂S₃ as anodes in sodium ion batteries (SIBs) has been attempted by forming Bi₂O₃@Bi₂S₃ and Bi₂S₃@Bi₂O₃ core@shell nanostructures. The presence of Bi₂S₃ in the outer shell results in poor electrochemical performance because of polysulfide leaching. Carbon derived from biowaste like custard apple seeds has been composited with the above core@shell bismuth chalcogenides, and their electrochemical properties have been investigated. It is observed that the addition of carbon reduces polysulfide leaching and balances the inherent drawback of volume alteration in metal chalcogenide anodes. The electrochemical performance of the electrodes was investigated by electrochemical impedance spectroscopy measurements. This work establishes that the mechanical stability of the Bi₂O₃ shell can improve the cycling stability, rate capability, and specific capacity of Bi₂S₃. The Bi₂S₃@Bi₂O₃/C composite combines the benefits of Bi₂S₃ and Bi₂O₃, with Bi₂S₃ nanoparticles enhancing the ion diffusion kinetics and specific capacity while Bi₂O₃ preserves the excellent cycling stability.