SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 210096, China.
Condensed Matter Physics &Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
Nat Commun. 2017 May 24;8:15400. doi: 10.1038/ncomms15400.
Multiple lithium-ion transport pathways and local phase changes upon lithiation in silver hollandite are revealed via in situ microscopy including electron diffraction, imaging and spectroscopy, coupled with density functional theory and phase field calculations. We report unexpected inter-nanorod lithium-ion transport, where the reaction fronts and kinetics are maintained within the neighbouring nanorod. Notably, this is the first time-resolved visualization of lithium-ion transport within and between individual nanorods, where the impact of oxygen deficiencies is delineated. Initially, fast lithium-ion transport is observed along the long axis with small net volume change, resulting in two lithiated silver hollandite phases distinguishable by orthorhombic distortion. Subsequently, a slower reaction front is observed, with formation of polyphase lithiated silver hollandite and face-centred-cubic silver metal with substantial volume expansion. These results indicate lithium-ion transport is not confined within a single nanorod and may provide a paradigm shift for one-dimensional tunnelled materials, particularly towards achieving high-rate capability.
通过原位显微镜包括电子衍射、成像和光谱学，结合密度泛函理论和相场计算，揭示了银水钙石在锂化过程中存在多种锂离子传输途径和局部相变化。我们报告了意想不到的纳米棒间锂离子传输，其中反应前沿和动力学在相邻纳米棒内保持不变。值得注意的是，这是首次在时间分辨尺度上可视化单个纳米棒内和之间的锂离子传输，其中明确了氧缺陷的影响。最初，观察到沿着长轴的快速锂离子传输，伴随着小的净体积变化，导致可以通过正交畸变区分的两种锂化银水钙石相。随后，观察到较慢的反应前沿，形成多相锂化银水钙石和面心立方银金属，伴随着显著的体积膨胀。这些结果表明锂离子传输不限于单个纳米棒内，这可能为一维隧道材料提供一个范式转变，特别是在实现高倍率能力方面。
