Electrochemical performance and lithium-ion insertion/extraction mechanism studies of the novel Li₂ZrO₃ anode materials

Li₂ZrO₃ anode materials were prepared by the conventional solid-state reaction. The crystal structure has been determined by X-ray diffraction. Electrochemical tests show that Li₂ZrO₃ anode materials process a excellent cycle performance and rate capability due to the good structural stability and high lithium diffusion coefficients. For the Li₂ZrO₃ anode material, the change of the unit cell volume is only ∼0.3% at discharge or charge process. Except for the first several cycles, the coulombic efficiency of the Li₂ZrO₃ electrode was nearly 100% at a discharge/charge rate of 0.3 C. The lithium diffusion coefficients of Li₂ZrO₃ for the reduction and oxidation process are calculated to be 3.165 × 10⁻⁶ and 1.919 × 10⁻⁶ cm² s⁻¹ respectively which is much higher than that of the Li₄Ti₅O₁₂ anode material (about 10⁻⁹ to 10⁻¹³ cm² s⁻¹). In situ XRD results, combined the sloping character of the charge/discharge voltage profiles and the lithium ion diffusion controlled mechanism in the charge and discharge process, show that the insertion/extraction mechanism of Li⁺ for Li₂ZrO₃ can be interpreted as a solid-solution behavior