Insights about the irreversible capacity of LiNi0.5Mn1.5O4 cathode materials in lithium batteries
Insights about the irreversible capacity of LiNi0.5Mn1.5O4 cathode materials in lithium batteries
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DOI：
10.1016/j.electacta.2013.05.111
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发表时间：
2013-09-01
影响因子：
6.6
通讯作者：
Panero, Stefania
中科院分区：
文献类型：
--
作者：
Brutti, Sergio;Greco, Giorgia;Panero, Stefania
在第一次循环和循环后的不可逆容量的积累进行了研究的LiNi0.5Mn1.5O4基阴极（LNMO），裸和涂覆有ZnO。材料已经在800摄氏度下合成，并通过X射线衍射和透射电子显微镜（TEM）进行表征。透射电镜观察到在LNMO表面形成了连续的ZnO薄膜。采用室温和60 ℃恒电流循环、线性扫描伏安法（LSV）、阻抗谱和透射电镜等技术研究了材料的电化学行为和循环过程中的不可逆容量积累，证实了材料在首次充放电后的循环过程中存在连续的寄生过程。阳极LSV测试表明，侧氧化过程开始于电位略高于Ni 2 +/Ni 4+氧化还原电对的LNMO电极表面。在充电结束时，在裸LNMO上形成均匀且连续的薄膜（3-4 nm）。该膜可能在循环时改性，并且显然不能钝化LNMO表面，从而防止进一步分解。相反，涂覆有ZnO的材料显示出粗糙的表面，在充电和循环时没有大的形态变化。ZnO涂层证实了其减轻不可逆电荷消耗的能力。(C)2013爱思唯尔有限公司保留所有权利。
The accumulation of irreversible capacity in the first cycle and upon cycling has been studied for LiNi0.5Mn1.5O4-based cathodes (LNMO), bare and coated with ZnO. Materials have been synthesized at 800 degrees C and characterized by X-ray diffraction and transmission electron microscopy (TEM). The precipitation of a continuous ZnO film on the surface of LNMO has been highlighted by TEM. Galvanostatic cycling at room temperature and at 60 degrees C, linear sweep voltammetry (LSV), impedance spectroscopy and TEM techniques have been used to investigate the materials and the irreversible capacity accumulation upon cycling.Our study confirms that continuous parasitic processes occur upon cycling beyond the first charge/discharge. Anodic LSV test shows that side oxidation processes start on the surface of a LNMO electrode at potential slightly above the Ni2+/Ni4+ redox couple. At the end of charge an uniform and continuous thin film (3-4 nm) forms of on the bare LNMO. This film likely modifies upon cycling and it is apparently unable to passivate the LNMO surface preventing further decompositions. On the contrary the material coated with ZnO shows rough surfaces without large morphological alteration upon charge and cycling. The ZnO coating confirms its ability to mitigate the irreversible charge consumption. (C) 2013 Elsevier Ltd. All rights reserved.