Core-shell structure and high rate performance of Ce-doped Li4Ti5O12 for lithium-ion battery anode materials

Abstract

Lithium titanate (LTO) can be a very promising anode material for lithium-ion batteries (LSBs) due to its inherent ability to inhibit the growth of lithium dendrites as well as its unique “zero-strain” properties. Unfortunately, the low electronic conductivity of LTO leads to serious shortcomings in higher electrochemical demands. In this work, the Ce³⁺-doped C@Li₄Ti₅-_xCe_xO₁₂ (x = 0, 0.1, 0.15 and 0.2) anode materials synthesized by the hydrothermal method using carbon spheres as templates showed more significant improvement in both structural and electrochemical properties. The results demonstrate that electronic conductivity, lithium-ion diffusion rate, discharge specific capacity, discharge rate capability, and significant improvement stability of C@Li₄Ti₅-_xCe_xO₁₂ (x = 0.1, 0.15 and 0.2) electrodes. Among them, C@Li₄Ti_4.85Ce_0.15O₁₂ electrode exhibits the highest initial discharge specific capacity (250.86 mAh/g) at 0.1C, which is 1.28-fold that of C@ Li₄Ti₅O₁₂ (195.94 mAh/g), and initial discharge capacity from 205.96 mAh/g to 170.39 mAh/g after 500 cycles, corresponding to 82.7 % of the initial stable discharge capacity. The outstanding performance of C@Li₄Ti_4.85Ce_0.15O₁₂ can be attributed to the lower interfacial impedance, higher electronic conductivity, high oxygen vacancy concentration, and moderate amount of Ce³⁺ doping can enhance the electrochemical activity. In addition, carbon sphere surface defects shown to be effective in improving lithium-ion storage. This work demonstrates that Ce³⁺ doping is an effective method to improve the electrochemical performance of LTOs and provides a more effective guide for designing and optimizing anode electrode materials for lithium-ion batteries.