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摘要
In the present work, three types of Li1.2Ni0.2Mn0.6O2 were synthesized from sodium birnessite (NaBir) and each type exhibited distinct morphological features created by varying preparation (with or without ball milling) or varying the sequential order of the preparation steps. Three processes were employed, including (1) ion-exchange, simply mechanical mixing, calcination (Without-BM), (2) ion-exchange, ball milling, calcination (EX-priority), (3) ball milling, ion-exchange, calcination (BM-priority). The three as-prepared sample types exhibited different performance characteristics, depending on their respective preparation processes. The "Without-BM'' sample exhibited a reversible capacity of 240 mA h g (1) between 2.0 V and 4.8 V with a current density of 0.1 C (30 mA g (1)), having almost no capacity fading after 80 cycles. The "EX-priority'' sample exhibited a desirable rate performance with a reversible capacity of 213.4 mA h g (1) at 1 C and 136.4 mA h g (1) at 7 C; however, the capacity retention was 88.3% after 80 cycles at 0.1 C. The "BM-priority'' sample displayed a moderate rate and cycle performance. The differences between these samples demonstrated that the ball milling treatment and its sequence have substantial effects on performance of materials. The experimental data indicated that the different performances can be attributed to the different morphologies of the respective materials as well as the effect of sodium ion concentration within the structure. Therefore, controlling the morphology of the material and the amount of sodium ions in its structure may be advantageous for developing high quality cathode materials which can be diversified for specific applications in Li-ion batteries.
- 出版日期2014-8-15
- 单位苏州大学
