Thermal treatment of TiO₂-CuI mixtures to improve the electrochemical properties of TiO₂ anodes for lithium-ion batteries

Abstract

A novel finding, that the electrochemical performance of titanium dioxide (TiO₂) can be significantly promoted through treating the mixture containing TiO₂ and cuprous iodide (CuI) thermally, is presented for the first time in this work. Firstly, a mixture containing TiO₂ and CuI is prepared carefully, in which the molar ratio of Ti and Cu is 3:1. Secondly, the obtained mixtures are thermally treated at 360 °C, 420 °C and 480 °C in air for 2 h, respectively, producing sample a, b and c. As revealed by the XRD and XPS results, TiO₂ and CuO are the principal components of all the thermal treatment products. Above all things, when being utilized as anode materials of lithium ion batteries (LIBs), all the thermal treatment products exhibit superior battery performances relative to that of the pure TiO₂, for instance, the initial discharge capacities of sample a, b and c at 0.1 A g⁻¹ are about 276.1, 422.7 and 294.9 mAh g⁻¹, respectively, being about 1.25, 1.91 and 1.33 times higher than that of pure TiO₂ (221.0 mAh g⁻¹). Particularly, the high rate performances of all the thermal treatment products, especially sample b, are still better than the pure TiO₂. For example, the discharge capacity of sample b at 1.0 A g⁻¹ after 100 cycles is tested to be 84 mAh g⁻¹, being about 1.5 times higher than that of pure TiO₂ (56 mAh g⁻¹). The reduction in the charge transfer resistance and the increase in the cyclic voltammetry peak area are analyzed to be the major reasons endowing all the thermal treatment products especially sample b a greatly promoted battery performance. Showing the fact, that thermally treating the mixture having TiO₂ and CuI is a practical technique to significantly promote the battery performance of TiO₂, is the principal dedication of this preliminary work.