采用溶胶-凝胶法结合固相反应制备了具有立方尖晶石结构的LiMn1-xNixTiO4(x=0、0.1、0.2、0.3)锂离子电池正极材料。通过场发射扫描电镜(FESEM)观察材料的表面形貌,所制备的材料均呈现出典型的烧结体特征；用X射线衍射仪(XRD)分析材料的物相变化, Ni替代前后均产生杂相TiO2,但没有产生与替代元素相关的杂相。通过循环伏安、恒电流充放电等测试研究样品的电化学性能。结果表明： LiMnTiO4有两对氧化还原峰,分别对应Mn3+/Mn4+、Mn3+/Mn2+的转变,而Ni替代后出现了额外的氧化还原对,即Ni3+/Ni4+的转变。LiMn1-xNixTiO4(x=0.1、0.2、0.3)的电化学性能均优于LiMnTiO4,尤其当Ni替代量为0.1时, LiMn0.9Ni0.1TiO4在30 mA/g电流密度下的首次放电容量为171.6 mAh/g,48次循环后容量为162.8 mAh/g,容量保持率为82.7%。对LiMn0.9Ni0.1TiO4进行非原位XRD测试发现,材料一次循环后结构无明显变化,不存在立方相与四方相之间的转变。
Spinel LiMn1-xNixTiO4(x=0, 0.1, 0.2, 0.3) cathode materials were prepared by Sol-Gel method. The surface morphology and phase structure of LiMn1-xNixTiO4(x=0, 0.1, 0.2, 0.3) were characterized by FESEM and XRD. FESEM analysis indicated all the samples consisted of irregular particles and XRD patterns showed that all the materi-als had impurity TiO2, but there were no impurities related to Ni element. Electrochemical studies of doped and un-doped spinels were carried out by cyclic voltammetry (CV) and constant current charge-discharge. CV results showed that LiMnTiO4 had two couples of sharp redox peaks corresponding to Mn3+/Mn4+, Mn2+/Mn3+ redox reactions. How-ever, after Ni substitution, there appeared the third redox coupled, which was related to the Ni3+/Ni4+ redox reaction. LiMn1-xNixTiO4(x=0.1, 0.2, 0.3) exhibited improved electrochemical properties compared with LiMnTiO4. When the Ni substitution was 0.1, the first discharge capacity of LiMn0.9Ni0.1TiO4 was 171.6 mAh/gat current density of 30 mA/g, and after 48 charge-discharge cycles, the discharge capacity was 162.8 mAh/g, with the capacity retention of 82.7%. The Ex XRD pattern of LiMn0.9Ni0.1TiO4 showed that the material structure had no changes after the first cycle, and there was no transition between cubic phase and tetragonal phase.
参考文献
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%