Acid-assisted synthesis of dandelion-like rutile TiO2 and Li4Ti5O12 mesoporous spheres: towards an efficient lithium battery application

Abstract

In this study, a new acid-assisted hydrothermal method was presented for the synthesis of dandelion-like mesoporous rutile TiO₂ microspheres (MSPs) without using any template and surfactant. With this strategy, the spherical structure and pore size of the obtained TiO₂ particles could be readily controlled just through varying the kind of acid (e.g., HNO₃–TiO₂ and HCl–TiO₂ MSPs show different pore size distribution of 6 ± 2 nm and 12 ± 2 nm, respectively). Benefiting from the mesoporous structure, high specific surface area, and especially the high percentage of exposed (002) crystal facets, the samples of HNO₃–TiO₂ and HCl–TiO₂ MSPs exhibit excellent electrochemical performance in lithium-ion batteries. For example, a high capacity of around 164.5 and 160.6 mA h g⁻¹ at a rate of 0.1 C, and a reversible capacity of over 141.9 and 133.3 mA h g⁻¹ after 100 cycles at a rate of 1 C were demonstrated respectively for the samples of HNO₃–TiO₂ and HCl–TiO₂ MSPs (1 C = 168 mA h g⁻¹). Moreover, another two kinds of mesoporous Li₄Ti₅O₁₂ spheres (HNO₃–Li₄Ti₅O₁₂ and HCl–Li₄Ti₅O₁₂ MSPs) were further prepared based on the above TiO₂ precursors. Promisingly, they also showed a higher improved performance in lithium battery application, such as a high capacity of around 173.6 and 174 mA h g⁻¹ at a rate of 0.1 C and a reversible capacity of over 161.9 mA h g⁻¹ and 170.4 mA h g⁻¹ after 100 cycles at a rate of 1 C (1 C = 175 mA h g⁻¹).