| 层状正极材料LiNi0.5Co0.25Mn0.25O2的结构及电化学行为 |
| Structural Characteristics and Electrochemical Behavior of Layered LiNi0.5Co0.25Mn0.25O2 as Cathode Materials of Lithium Ion Batteries |
|
| 摘要: 采用溶胶-凝胶方法制备了正极材料LiNi0.5Co0.25Mn0.25O2。XRD、XPS测试结果表明：LiNi0.5Co0.25Mn0.25O2中阳离子排列有序度较高，层状结构明显；Co、Mn分别以+3、+4价形式存在，Ni以+2、+3价形式存在，且Ni2+与Ni3+的含量之比约为1∶1。SEM测试结果表明：正极材料LiNi0.5Co0.25Mn0.25O2结晶粒径较均匀。充放电测试结果表明：与LiCoO2相比，尽管LiNi0.5Co0.25Mn0.25O2的放电电压平台较低，但放电容量较高；在恒流充电模式下，当充电截止电压由4.35 V升高至4.75 V时，首次放电容量由179 mAh·g-1增至201 mAh·g-1，50次循环后，容量保持率由74.95%增至78.48%；在先恒流再恒压的充电模式下，电池首次放电容量为212 mAh·g-1，50次循环后，容量保持率提高到87.71%。循环伏安测试表明：在2.80～4.80 V扫描范围内，该正极材料发生Ni2+/Ni3+，Co3+/Co4+两对电化学反应。EIS测试表明：随着充电截止电压的增大，该正极材料的传荷电阻变小。 |
| 关键词: 锂离子电池 层状正极材料 LiNi0.5Co0.25Mn0.25O2 电化学性能 |
| 基金项目: |
| Abstract: Cathode materials of LiNi0.5Co0.25Mn0.25O2 was synthesized by Sol-gel method in this study. XRD and XPS results reveal that the obtained LiNi0.5Co0.25Mn0.25O2 exhibits a typical layered structure composed of highly ordered Co3+, Mn4+, Ni2+ and Ni3+; and the atom ratio of Ni2+ to Ni3+ is 1∶1. A morphology of homogeneously distributed and well cyrstallized is observed by SEM. Compared with LiCoO2, the resulted materieals possess larger capacity and lower voltage plateau. It is also found that the initial discharge capacity and capacity retention of 50th cycle of LiNi0.5Co0.25Mn0.25O2 increase from 179 mAh·g-1 to 201 mAh·g-1, from 74.95% to 78.48%, respectivley, when the cutoff voltage is changed from 4.35 V to 4.75 V. Under the discharge-charge model of initial constant current and subsequent constant voltage, an initial discharge capacity of 212 mAh·g-1 can be achieved and the material keeps 87.71% of its initial capacity after 50th cycle. CV and EIS tests show that two redox couples of Ni2+/Ni3+ and Co3+/Co4+ are observed in the potential range of 2.80～4.80 V, and charge transfer resistance of the cathode decreases as the charge cutoff voltage increased. |
| Keywords: lithium ion batteries layered cathode materials LiNi0.5Co0.25Mn0.25O2 electrochemical behavior |
| |
| 摘要点击次数: 1617 |
| 全文下载次数: 2433 |
| 戴长松,葛昊,王殿龙,王福平.层状正极材料LiNi0.5Co0.25Mn0.25O2的结构及电化学行为[J].无机化学学报,2007,23(3):432-438. |
| 查看全文 查看/发表评论 下载PDF阅读器 |
| Support information: |
|
|
|
|
|
|
