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

Abstract A kinetically favored Cd 2+ and Ge 4+ dual‐doped lithium titanate (Li 4 Ti 5 O 12 ) anode material is designed for lithium‐ion batteries (LIBs). Rietveld refinement reveals that introducing a 0.05 wt.% of Cd 2+ at Li(8 a ) and Ge 4+ at Ti(16 d ) sites brings no structural change in the spinel Li 4 Ti 5 O 12 . Scanning transmission electron microscopy (STEM) identifies Cd 2+ and Ge 4+ are homogenously doped in the Li 4 Ti 5 O 12 lattice. High‐resolution powder diffraction (HRPD) confirmed that Cd 2+ and Ge 4+ doping in Li 4 Ti 5 O 12 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 Ti 4+ to Ti 3+ ions on the surface of 0.05‐Cd‐Ge‐LTO electrodes to the pristine LTO. Furthermore, the 0.05‐Cd‐Ge‐Li 4 Ti 5 O 12 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‐Li 4 Ti 5 O 12 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 Cd 2+ at Li(8 a ) and Ge 4+ at Ti(16 d ) sites in the Li 4 Ti 5 O 12 lattice is an effective approach to obtain superior electrochemical performance as anode material in LIBs.