Boesenberg Ulrike, Meirer Florian, Liu Yijin, Shukla Alpesh K, Dell'anna Rossana, Tyliszczak Tolek, Chen Guoying, Andrews Joy C, Richardson Thomas J, Kostecki Robert, Cabana Jordi
Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720.
Chem Mater. 2013 May 14;25(9):1664-1672. doi: 10.1021/cm400106k.
The chemical phase distribution in hydrothermally grown micrometric single crystals LiFePO following partial chemical delithiation was investigated. Full field and scanning X-ray microscopy were combined with X-ray absorption spectroscopy at the Fe K- and O K-edges, respectively, to produce maps with high chemical and spatial resolution. The resulting information was compared to morphological insight into the mechanics of the transformation by scanning transmission electron microscopy. This study revealed the interplay at the mesocale between microstructure and phase distribution during the redox process, as morphological defects were found to kinetically determine the progress of the reaction. Lithium deintercalation was also found to induce severe mechanical damage in the crystals, presumably due to the lattice mismatch between LiFePO and FePO. Our results lead to the conclusion that rational design of intercalation-based electrode materials, such as LiFePO, with optimized utilization and life requires the tailoring of particles that minimize kinetic barriers and mechanical strain. Coupling TXM-XANES with TEM can provide unique insight into the behavior of electrode materials during operation, at scales spanning from nanoparticles to ensembles and complex architectures.
研究了水热生长的微米级单晶LiFePO在部分化学脱锂后的化学相分布。全场和扫描X射线显微镜分别与Fe K边和O K边的X射线吸收光谱相结合，以生成具有高化学和空间分辨率的图谱。将所得信息与通过扫描透射电子显微镜对转变机制的形态学洞察进行比较。这项研究揭示了氧化还原过程中微观结构和相分布在中尺度上的相互作用，因为发现形态缺陷在动力学上决定了反应的进程。还发现锂脱嵌会在晶体中引起严重的机械损伤，这可能是由于LiFePO和FePO之间的晶格失配所致。我们的结果得出结论，合理设计基于嵌入的电极材料，如LiFePO，以实现优化的利用率和寿命，需要对颗粒进行剪裁，以最小化动力学障碍和机械应变。将TXM-XANES与TEM耦合可以在从纳米颗粒到聚集体和复杂结构的尺度上，对电极材料在运行过程中的行为提供独特的见解。
