Synthesis of ceria-carbon composite spheres and their application for next-generation lithium rechargeable batteries

CeO₂ is known to have considerable potential for use as a novel anode material in lithium-ion batteries, but it has inherently low electronic conductivity and low capacity retention due to volumetric or morphological changes during charge–discharge cycling. In this study, we developed an effective synthetic strategy based on the modified Stöber method for the first time to obtain CeO₂–carbon composite spheres (CeO₂–CCS) using PAA (poly(acrylic acid)) and compared it with CeO₂–carbon core shell (CeO₂@C) formed without PAA. The CeO₂–CCS showed that the CeO₂ nanoparticles are well dispersed in the composite spheres with a rough surface, and the surface is coated with an amorphous carbon layer with a thickness of approximately 1–2 nm. This novel architecture provides good access to the electrolyte and accommodates the volume expansion of CeO₂ during electrochemical cycling, thereby showing the rate capability and cyclability of CeO₂–CCS higher than CeO₂@C. We also identified the reaction mechanism of CeO₂ using synchrotron-based X-ray absorption spectroscopy. This study provides a comprehensive understanding and strategy for CeO₂ as a promising material for anode materials in lithium-ion batteries.