文摘
A facile solid-state method to improve the rate performance of Li4Ti5O12 in lithium-ion batteries by LiAlO2 in situ modification is presented in this work. XRD shows that the LiAlO2 modification does not change the spinel structure of Li4Ti5O12 but forms Al-doped Li4Ti5O12–LiAlO2 composites, and little Al doping decreases the lattice parameter of doped Li4Ti5O12. SEM shows that all samples are composed of 1–2 μm primary particles with irregular shapes. Raman spectra reveal that the intensity of these lines for Li4Ti5O12–LiAlO2 composites obviously decreases caused by a modification of the LiAlO2 phase. CV and EIS tests indicate that the doping of Al3+ and the combination with in situ generated LiAlO2 on the surface of Li4Ti5O12 are favorable for reducing the electrode polarization and charge-transfer resistance, and then improve the reversibility and lithium ion diffusion coefficient of Li4Ti5O12, resulting in its relatively higher rate capacity. Charge–discharge tests reveals that Li4Ti5O12–LiAlO2 composite (5 wt %) exhibits the highest rate capacity and cycling stability at various rates, which is capable of large-scale applications, such as electric vehicles and hybrid electric vehicles, requiring high energy, long life and excellent safety.