Synthesis of sandwich-like TiO2@C composite hollow spheres with high rate capability and stability for lithium-ion batteries

Abstract

Novel sandwich-like TiO2@C composite hollow spheres with {001} facets exposed are obtained through hydrothermal carbon-coating treatment for the first time. Based on investigations by transmission electron microscopy (TEM), scanning electron microscopy (FESEM), XRD, laser Raman spectra, and N2 adsorption–desorption isotherms, TiO2 shells are proved to be wrapped in porous carbon layers, which provide conductive support for TiO2, resulting the improvement in electronic conductivity and diffusion of Li+. Moreover, these TiO2 shells expose the reactive {001} facets, which facilitate Li+ insertion/extraction. Through combining the above advantages, TiO2@C composite hollow spheres show more superior rate capability and higher stability than TiO2 nanoparticles (Degussa P25), TiO2 nanosheets with {001} facets exposed, and TiO2 hollow spheres before carbon-coating. This method may be extended to synthesize other sandwich-like composite hollow spheres for energy storage.