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摘要
In this study, vanadium (V) was firstly used to dope alone or with molybdenum (Mo) in Li[Li0.2Mn0.54Co0.13Ni0.13]O-2 to enhance its electrochemical performance. A series of V-doped lithium-rich materials Li1.2Mn0.54-xNi0.13Co0.13VxO2 (0 <= x <= 0.04) and V/Mo co-doped lithium-rich materials Li1.2Mn0.54-x-yNi0.13Co0.13VxMoyO2 (0.02 <= x <= 0.03, 0 <= y <= 0.03) with varied doping ratios have been successfully synthesized through a sol-gel method. The XRD results indicate that both Li1.2Mn0.54-xNi0.13Co0.13VxO2 (0 <= x <= 0.04) and Li1.2Mn0.54-x-yNi0.13Co0.13VxMoyO2 (0.02 <= x <= 0.03, 0 <= y <= 0.03) materials have a typical hexagonal alpha-NaFeO2 structure. The electrochemical performance of the original and doped Li[Li0.2Mn0.54Co0.13Ni0.13]O-2 samples was evaluated. The results present that cycling performance of Li1.2Mn0.54-xNi0.13Co0.13VxO2 materials is significantly enhanced in comparison to the original material. When the doping amount of V is 0.02, the discharge capacity of the Li1.2Mn0.54-xNi0.13Co0.13VxO2 materials after 300 cycles at 1 C (142.0 mA h/g) is slightly higher than the initial value (140.3 mA h/g) and that of undoped materials (112.0 mA h g(-1) after 150 cycles at 1 C). The rate performance of V and Mo co-doped materials is significantly improved. When x = 0.03 and y = 0.03, the discharge capacity of the Li1.2Mn0.54-x-yNi0.13Co0.13VxMoyO2 materials at 5 C is 52.7% of that at 0.1 C while the discharge capacity ratio of the single-doped V materials is only 39.8%. The doping of V and Mo can effectively inhibit the transformation of Li[Li 0.2Mn0.54Co0.13Ni0.13]O-2 materials from layered structure to spinel structure in the charging-discharging process, and increase the ionic conductivity of the Li [Li0.2Mn0.54Co0.13Ni0.13]O-2 materials, thus the electrochemical properties of the materials are obviously improved.
- 出版日期2019-1
- 单位哈尔滨工业大学
