Smith Paul F, Wang Lei, Bock David C, Brady Alexander B, Lutz Diana M, Yang Shize, Hu Xiaobing, Wu Lijun, Zhu Yimei, Marschilok Amy C, Takeuchi Esther S, Takeuchi Kenneth J
Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.
Department of Chemistry, Valparaiso University, Valparaiso, Indiana 46383, United States.
Inorg Chem. 2020 Mar 16;59(6):3783-3793. doi: 10.1021/acs.inorgchem.9b03443. Epub 2020 Mar 4.
A series of tunnel structured V-substituted silver hollandite (AgVMnO, = 0-1.4) samples is prepared and characterized through a combination of synchrotron X-ray diffraction (XRD), synchrotron X-ray absorption spectroscopy (XAS), laboratory Raman spectroscopy, and electron microscopy measurements. The oxidation states of the individual transition metals are characterized using V and Mn K-edge XAS data indicating the vanadium centers exist as V, and the Mn oxidation state decreases with increased V substitution to balance the charge. Scanning transmission electron microscopy of reduced materials shows reduction-displacement of silver metal at high levels of lithiation. In lithium batteries, the V-substituted tunneled manganese oxide materials reveal previously unseen reversible nonaqueous Ag electrochemistry and exhibit up to 2.5× higher Li storage capacity relative to their unsubstituted counterparts. The highest capacity was observed for the Ag(VMn)O·0.8HO material with an intermediate level of V substitution, likely due to a combination of the atomic composition, the morphology of the particle, and the homogeneous distribution of the active material within the electrode structure where factors over multiple length scales contribute to the electrochemistry.
制备了一系列隧道结构的V取代银锰矿（AgVMnO，= 0 - 1.4）样品，并通过同步辐射X射线衍射（XRD）、同步辐射X射线吸收光谱（XAS）、实验室拉曼光谱和电子显微镜测量等手段对其进行了表征。利用V和Mn K边XAS数据表征了各过渡金属的氧化态，结果表明钒中心以V形式存在，且随着V取代量的增加，Mn的氧化态降低以平衡电荷。对还原材料的扫描透射电子显微镜观察表明，在高锂化水平下银金属发生了还原位移。在锂电池中，V取代的隧道型锰氧化物材料展现出了前所未见的可逆非水Ag电化学性质，并且相对于未取代的对应材料，其锂存储容量高出2.5倍。对于具有中等V取代水平的Ag(VMn)O·0.8H₂O材料，观察到了最高的容量，这可能是由于原子组成、颗粒形态以及活性材料在电极结构内的均匀分布等多种因素共同作用的结果，其中多个长度尺度的因素对电化学性质都有贡献。
