Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model
Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model
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DOI：
10.1038/nmat2230
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发表时间：
2008-08-01
期刊：
影响因子：
41.2
通讯作者：
Weill, F.
中科院分区：
文献类型：
--
作者：
Delmas, C.;Maccario, M.;Weill, F.
磷酸铁锂是下一代锂离子电池最有前途的正极材料之一，将用于电动和插电式混合动力汽车。锂脱嵌（嵌入）是通过非常接近 LiFePO4 和 FePO4 的成分之间的两相反应进行的。由于两个端元相都是非常差的离子和电子导体，因此很难在微观尺度上理解插层机制。在这里，我们报告了通过 X 射线衍射和电子显微镜对电化学脱嵌纳米材料的表征，显示了完全嵌入和完全脱嵌的单个颗粒的共存。该结果表明生长反应比其成核反应快得多。反应机理由“多米诺骨牌级联模型”描述，并通过仅在反应界面处发生的结构约束的存在来解释：弹性能的最小化增强了作为波穿过整个晶体移动时发生的脱嵌（嵌入）过程。该模型为寻找新的电极材料（即使离子和电子电导率较差）开辟了新的视角。
Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO4 and FePO4. As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a 'domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities.