Effect of rich R-TiO2 on the rate and cycle properties of Li4Ti5O12 as anode for lithium ion batteries

Li4Ti5012 (LTO) with rich R-TiO2 (17.06, 23.69, and 34.42 wt%), namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate (TBT) as the precursor. Rietveld refinement of X-ray diffraction (XRD) results show that the proportion of Li occupying 16d sites is extraordinary low and the lattice constants of LTO and R-TiO2 change with the ritanium dioxide content. EIS measurements showed that with in creasing R-TiO2 content, both its charge transfer impedance (Rct) and lithium ion diffusion coefficient (DLi) decreased. The changes of Rct and DLi caused by the increase of titanium dioxide content have synergic-antagonistic effects on the rate and cycle properties of Li4Ti5012. The rate performance is positively related to DLi, while the cycle property is negatively correlated with Rct, indicati ng that the rate performs nee is mainly related to DLi, while Rct more significantly affects the cycle performance. LTO-RT-17.06% exhibited excellent rate properties, especially under a high current density (5.0 C, 132.5 mAh/g) and LTO-RT-34.42% showed superior long-term cycle performance (0.012% capacity loss per cycle) compared to that of LTO-RT-17.06% and LTO-RT-23.69%.

Li4Ti5O12（LTO） with rich R-TiO2（17.06, 23.69, and 34.42 wt%）, namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate（TBT） as the precursor. Rietveld refinement of X-ray diffraction（XRD） results show that the proportion of Li occupying 16 d sites is extraordinary low and the lattice constants of LTO and R-TiO2 change with the titanium dioxide content. EIS measurements showed that with increasing R-TiO2 content, both its charge transfer impedance（Rct） and lithium ion diffusion coefficient（DLi） decreased. The changes of Rctand DLicaused by the increase of titanium dioxide content have synergic-antagonistic effects on the rate and cycle properties of Li4Ti5O12. The rate performance is positively related to DLi, while the cycle property is negatively correlated with Rct,indicating that the rate performance is mainly related to DLi, while Rctmore significantly affects the cycle performance. LTO-RT-17.06% exhibited excellent rate properties, especially under a high current density（5.0 C, 132.5 mAh/g） and LTO-RT-34.42% showed superior long-term cycle performance（0.012% capacity loss per cycle） compared to that of LTO-RT-17.06% and LTO-RT-23.69%.