Direct Observation of a Metastable Crystal Phase of LixFePO4 under Electrochemical Phase Transition
Direct Observation of a Metastable Crystal Phase of LixFePO4 under Electrochemical Phase Transition
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DOI：
10.1021/ja312527x
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发表时间：
2013-04-17
影响因子：
15
通讯作者：
Ogumi, Zempachi
中科院分区：
文献类型：
--
作者：
Orikasa, Yuki;Maeda, Takehiro;Ogumi, Zempachi
采用时间分辨X射线衍射技术对非平衡电池工作过程中LiFePO4和FePO4之间的相变进行了真实的跟踪。随着电流密度的增加，除了结晶稳定的LiFePO4和FePO4相之外，还出现了亚稳晶相。在电化学循环之后的开路条件下，亚稳相逐渐减少。我们提出了一个相变路径，通过亚稳相和新相的作用，在降低成核能，占优异的倍率性能的磷酸铁锂。这项研究是第一次报告的测量过程中的电化学相变的LixFePO4的亚稳晶相。
The phase transition between LiFePO4 and FePO4 during nonequilibrium battery operation was tracked in real time using time-resolved X-ray diffraction. In conjunction with increasing current density, a metastable crystal phase appears in addition to the thermodynamically stable LiFePO4 and FePO4 phases. The metastable phase gradually diminishes under open-circuit conditions following electrochemical cycling. We propose a phase transition path that passes through the metastable phase and posit the new phase's role in decreasing the nucleation energy, accounting for the excellent rate capability of LiFePO4. This study is the first to report the measurement of a metastable crystal phase during the electrochemical phase transition of LixFePO4.