Composite with TiO2 and extension of discharge voltage range for capacity enhancement of a Li4Ti5O12 battery

Abstract

Herein, nanosheet-assembled Li₄Ti₅O₁₂–TiO₂ (LTO–TiO₂) microspheres were successfully obtained via a hydrothermal method. The structure and morphology of the composite were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Subsequently, the electrochemical performance of the product was determined by an electrochemical workstation and a LAND CT2001A (Land, China) battery testing system. The experimental results demonstrated that both the formation of a composite with anatase TiO₂ and the extension of the discharge voltage range were beneficial for the enhancement of the specific capacity of Li₄Ti₅O₁₂. When the discharge cut-off voltage was decreased to 0 V, the LTO–TiO₂ composites exhibited a higher discharge specific capacity of 411.3 mA h g⁻¹ during the first cycle in comparison with pure LTO, which was mainly attributed to the intercalation of more lithium ions into the LTO–TiO₂ composites at a low potential (<1.0 V). Moreover, owing to the introduction of anatase TiO₂, the Li⁺ charge/discharge process at a higher potential of around 2.0 V (vs. Li/Li⁺) was also favorable for the enhancement of the capacity of LTO composites and their applied voltage range. In addition, the LTO–TiO₂ composites exhibited high electronic conductivity and lithium ion diffusion coefficients and excellent coulombic efficiency.