National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
ACS Appl Mater Interfaces. 2013 May;5(9):3643-9. doi: 10.1021/am400105y. Epub 2013 Apr 22.
Electrochromic effects of transition metal oxides provide a great platform for studying lithium intercalation chemistry in solids. Herein, we report on an electronically modified nanocomposite nickel oxide (i.e., Li2.34NiZr0.28Ox) that exhibits significantly improved electrochromic performance relative to the state-of-the-art inorganic electrochromic metal oxides in terms of charge/discharge kinetics, bleached-state transparency, and optical modulation. The knowledge obtained from O K-edge X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) suggests that the internally grown lithium peroxide (i.e., Li2O2) species plays a major role in facilitating charge transfer thus enabling optimal electrochromic performance. This understanding is relevant to recent theoretical studies concerning conductivity in Li2O2 for lithium-air batteries (as cited in the main text). Furthermore, we elucidate the electrochromism in modified nickel oxide in lithium ion electrolyte with the aid of Ni K-edge XAS and Ni L-edge XAS studies. The electrochromism in the nickel oxide materials arises from the reversible formation of hole states on the NiO6 units, which then impacts the Ni oxidation state through the Ni3d-O2p hybridization states. This study sheds light on the lithium intercalation chemistry for general energy storage and semiconductor applications.
过渡金属氧化物的电致变色效应为研究固体中的锂离子嵌入化学提供了一个很好的平台。在此，我们报告了一种电子修饰的纳米复合氧化镍（即 Li2.34NiZr0.28Ox），与先进的无机电致变色金属氧化物相比，其在充放电动力学、漂白态透明度和光学调制方面具有显著改善的电致变色性能。O K 边 X 射线吸收光谱（XAS）和 X 射线光电子能谱（XPS）的知识表明，内部生长的过氧化锂（即 Li2O2）物种在促进电荷转移方面起着主要作用，从而实现了最佳的电致变色性能。这一认识与最近关于锂空气电池中 Li2O2 电导率的理论研究（如正文中所引用的）相关。此外，我们借助 Ni K 边 XAS 和 Ni L 边 XAS 研究阐明了锂离子电解质中改性氧化镍的电致变色。氧化镍材料的电致变色源于 NiO6 单元上的空穴态的可逆形成，这通过 Ni3d-O2p 杂化态影响 Ni 氧化态。这项研究为一般储能和半导体应用中的锂离子嵌入化学提供了启示。
