A novel spherically porous Zr-doped spinel lithium titanate (Li_4Ti_(5_x)Zr_xO_(12)) for high rate lithium ion batteries

摘要

Spinel Li_4Ti_(5)O_(12) has been demonstrated as a potential candidate for the anode material in lithium ion batteries because it has some unique characteristics as compared with carbon based anode materials. However, Li_4Ti_(5)O_(12) has rather low electronic conductivity and only a moderate Li~+ diffusion coefficient, which make it suffer from the problem of poor rate capability. In the present study, novel spherically porous Zr-doped Li_4Ti_(5_x)Zr_xO_(12) [x = 0.05, 0.1 and 0.2) anode materials were synthesized by using a rhe-ological phase in combination with a spray drying reaction route, and their electrochemical properties between OV and 3 V were investigated. The results reveal that the spherically porous Zr-doped Li_4Ti_(5_x)Zr_xO_(12)samples have better electrochemical performances than that of the pristine Li_4Ti_(5)O_(12) without Zr-doping, but too great an amount of Zr-doping is disadvantageous. The Li_4Ti_4.9Zr_0.1O_(12) exhibits the best rate capability and cycling stability among the Zr-doped samples. At the charge-discharge rate of 0.2 C, 5.0 C and 10.0 C between OV and 3 V, its initial discharge specific capacities were 308mAh/g, 229 mA h/g and 210 mA h/g, respectively. After 50 cycles at 3.0 C, it remained at 201 mA h/g. Moreover, below 1.0 V there are no obviously irreversible reduction peaks in the CV curves of spherically porous Zr-doped Li_4Ti_(5_x)Zr_xO_(12) electrodes even in the first cycle, which indicates that the electrolyte would not be reduced on the surfaces of Zr-doped Li_4Ti_(5_x)Zr_xO_(12) electrodes below 1.0 V. Therefore, there would be less gas generation of the lithium ion battery while using the Zr-doped Li_4Ti_(5_x)Zr_xO_(12) as the anode electrode.