Improving High‐Rate and Long‐Life Cycling of Li₄Ti₅O₁₂ Anode by Dual Doping of Cd²⁺ and Ge⁴⁺

Abstract

A kinetically favored Cd2+ and Ge4+ dual‐doped lithium titanate (Li4Ti5O12) anode material is designed for lithium‐ion batteries (LIBs). Rietveld refinement reveals that introducing a 0.05 wt.% of Cd2+ at Li(8a) and Ge4+ at Ti(16d) sites brings no structural change in the spinel Li4Ti5O12. Scanning transmission electron microscopy (STEM) identifies Cd2+ and Ge4+ are homogenously doped in the Li4Ti5O12 lattice. High‐resolution powder diffraction (HRPD) confirmed that Cd2+ and Ge4+ doping in Li4Ti5O12 brings expansion in the lattice, field emission scanning electron microscopy (FE‐SEM) shows the reduction in the particle size due to of Cd and Ge in the LTO lattice, and X‐ray photoluminescence spectroscopy (XPS) confirms the partial reduction of Ti4+ to Ti3+ ions on the surface of 0.05‐Cd‐Ge‐LTO electrodes to the pristine LTO. Furthermore, the 0.05‐Cd‐Ge‐Li4Ti5O12 electrode exhibits a superior rate performance and delivers a discharge capacity of ≈169.1 mAhg−1 at 0.1 current rates. It is worth mentioning that, the 0.05‐Cd‐Ge‐Li4Ti5O12 electrode brings outstanding cycling stability in Li+ half‐cell, having a capacity retention of 98.79% after 300 cycles at 2C. This proves that dual‐doping of Cd2+ at Li(8a) and Ge4+ at Ti(16d) sites in the Li4Ti5O12 lattice is an effective approach to obtain superior electrochemical performance as anode material in LIBs.