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

摘要

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).