Probing Thermally Induced Decomposition of Delithiated Li1.2-xNi0.15Mn0.55Co0.1O2 by in Situ High-Energy X-ray Diffraction
Probing Thermally Induced Decomposition of Delithiated Li1.2-xNi0.15Mn0.55Co0.1O2 by in Situ High-Energy X-ray Diffraction
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DOI：
10.1021/am502689f
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发表时间：
2014-08-13
影响因子：
9.5
通讯作者：
Chen, Zonghai
中科院分区：
文献类型：
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作者：
Lin, Chi-kai;Piao, Ying;Chen, Zonghai
锂离子电池的安全性一直是大规模应用的主要障碍。为了更好地了解电池材料在热滥用下的失效机理，利用原位高能x射线衍射研究了稀薄高能正极材料Li1.2-xNi0.15Mn0.66Co0.1O2在不锈钢高压胶囊中的分解过程。结果表明，电解液的存在对氧化过渡金属（TM）的热诱导分解有很大影响。在无电解质条件下，氧化后的TM由层状结构转变为无序li1 - xm2o4型尖晶石，起始温度为266℃；无序li1 - xm2o4型尖晶石分解为无序m3o4型尖晶石相，起始温度为327℃。当LiPF6盐存在时，分解开始温度为249℃，形成MnF2相。结果表明，适当优化电解液成分，即有机溶剂和锂盐，可以改变耗竭阴极的分解途径，从而提高锂离子电池的安全性。
Safety of lithium-ion batteries has been a major barrier to large-scale applications. For better understanding the failure mechanism of battery materials under thermal abuse, the decomposition of a delithiated high energy cathode material, Li1.2-xNi0.15Mn0.66Co0.1O2, in the stainless-steel high pressure capsules was investigated by in situ high energy X-ray diffraction. The data revealed that the thermally induced decomposition of the delithiated transition metal (TM) oxide was strongly influenced by the presence of electrolyte components. When there was no electrolyte, the layered structure for the delithiated TM oxide was changed to a disordered Li1-xM2O4-type spinel, which started at ca. 266 degrees C. The disordered Li1-xM2O4-type spinel was decomposed to a disordered M3O4-type spinel phase, which started at ca. 327 degrees C. In the presence of organic solvent, the layered structure was decomposed to a disordered M3O4-type spinel phase, and the onset temperature of the decomposition was ca. 216 degrees C. When the LiPF6 salt was also present, the onset temperature of the decomposition was changed to ca. 249 degrees C with the formation of MnF2 phase. The results suggest that a proper optimization of the electrolyte component, that is, the organic solvent and the lithium salt, can alter the decomposition pathway of delithiated cathodes, leading to improved safety of lithium-ion batteries.