Preparation and electrochemical performance of La3+ and F− co-doped Li4Ti5O12 anode material for lithium-ion batteries

• La3+, F− co-doped Li4Ti5O12 materials are synthesized via a solid state reaction.
• La3+ and F− ions enter the different sites of the crystal structure of Li4Ti5O12.
• La3+ and F− co-doping can improve the capacity and maintain the cycling stability.
• Li3.95La0.05Ti5O11.7F0.3 exhibits excellent rate and better cycle performance.

La3+ and F− co-doped Li4Ti5O12 (LTO) anode materials are synthesized successfully via a solid state reaction. The structure and morphology are characterized by XRD, SEM and EDS. The results indicate that La3+ and F− ions were uniformly dispersed in Li4Ti5O12 lattice without changing the structure and morphology of Li4Ti5O12. Li3.95La0.05Ti5O11.7F0.3 (La005-F03) exhibits an outstanding electrochemical performance among all the samples in a potential range from 0.5 to 2.5 V, and delivers a discharge capacity of 103 mAh g−1 at 10C rate, whereas the LTO only gives 62.5 mAh g−1. The sample La005-F03 retains a discharge capacity of 170.1 mAh g−1 after 100 cycles at 1C rate. The improved electrochemical performance could be attributed to the appropriate co-doping with La3+ and F−, which can increase the amount of Ti3+/Ti4+ mixing as charge compensation, leading to the decrease of the charge transfer resistance and improvement of the electronic conductivity and lithium ion diffusion coefficient.