Synthesis and high cycle performance of Li2ZnTi3O8/C anode material promoted by asphalt as a carbon precursor

Abstract

Li₂ZnTi₃O₈/C composites were synthesized by a solid-state method with asphalt as a carbon source. The effect of carbon content on the structure, morphology and electrochemical properties was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy (RS), galvanostatic charge–discharge and AC impedance spectroscopy. SEM images show that the as-prepared Li₂ZnTi₃O₈/C phase was agglomerated with a primary particle size of ca. 30 nm. TEM images reveal that a homogeneous carbon layer (ca. 3 nm) formed on the surface of Li₂ZnTi₃O₈ particles which are favorable to improve the electronic conductivity and inhibit the growth of Li₂ZnTi₃O₈ particles during the annealing process. Electrochemical measurements demonstrate that the as-prepared Li₂ZnTi₃O₈/C composite with 9.9 wt% carbon possesses a high initial discharge capacity of 393 mA h g⁻¹, 191 mA h g⁻¹ at 0.1 A g⁻¹ and 1 A g⁻¹, respectively. In addition, after 100 cycles at a high current density of 1 A g⁻¹, a discharge capacity of 191 mA h g⁻¹ is obtained (99.5% of its initial value).