LiNi0.5Mn1.5O4 Thin-Film Cathodes on Gold-Coated Stainless Steel Substrates: Formation of Interlayers and Electrochemical Properties
LiNi0.5Mn1.5O4 Thin-Film Cathodes on Gold-Coated Stainless Steel Substrates: Formation of Interlayers and Electrochemical Properties
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DOI：
10.1016/j.electacta.2014.03.184
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发表时间：
2014-07-01
影响因子：
6.6
通讯作者：
Roling, Bernhard
中科院分区：
文献类型：
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作者：
Gellert, Michael;Gries, Katharina I.;Roling, Bernhard
采用聚乙烯吡咯烷酮溶胶-凝胶法在镀金不锈钢衬底上制备了LiNi0.5Mn1.5O4（LNMO）薄膜。发现具有在1 μ m范围内的厚度的膜表现出接近理论的容量。通过电化学阻抗谱（EIS）、飞行时间二次离子质谱（ToF-SIMS）、扫描透射电子显微镜和能量色散X射线能谱（STEM/EDX）研究了LNMO膜与LP 30电解质（碳酸二甲酯（DMC）和碳酸乙烯酯（EC）的混合物（1：1 v/v），含1 mol.l（-1）LiPF 6）之间以及LNMO膜与镀金基底之间的夹层形成。这些方法的组合被证明是非常强大的理解的化学成分和性能的夹层，并确定起源的奈奎斯特阻抗图中的电阻。在LNMO/LP 30界面处，我们观察到厚度约为50 nm的中间层（固体电解质界面，SEI），而在LNMO/金界面处，发现厚度在250 nm范围内的混合氧化物层。虽然LNMO/LP 30夹层对界面阻抗有显著贡献，但LNMO/金夹层的阻抗似乎可以忽略不计，尽管其厚度较大。(C)2014爱思唯尔有限公司版权所有。
Thin films of LiNi0.5Mn1.5O4 (LNMO) were prepared on gold-coated stainless steel substrates via a poly(vinylpyrrolidone)-based sol-gel process. Films with a thickness in the range of 1 mu m were found to exhibit a capacity close to the theoretical one. The formation of interlayers (i) between the LNMO films and the LP30 electrolyte (mixture of dimethyl carbonate (DMC) and ethylene carbonate (EC) (1:1 v/v) containing 1 mol.l(-1) LiPF6) and (ii) between the LNMO films and the gold-coated substrate was studied by means of electrochemical impedance spectroscopy (EIS), time-of-flight secondary-ion mass-spectrometry (ToF-SIMS), and scanning transmission electron microscopy together with energy dispersive X-ray spectroscopy (STEM/EDX). The combination of these methods turns out to be very powerful for understanding the chemical composition and properties of interlayers and for identifying the origin of semicircles in Nyquist impedance plots. At the LNMO/LP30 interface, we observe an interlayer (solid electrolyte interface, SEI) with a thickness of about 50 nm, while at the LNMO/gold interface, a mixed oxide layer with a thickness in the range of 250 nm is found. The mixed oxide layer is caused by diffusion of Cr and Ni from the stainless steel through the gold layer. While the LNMO/LP30 interlayer contributes significantly to the interfacial impedance, the impedance of the LNMO/gold interlayer seems to be negligible, despite its larger thickness. (C) 2014 Elsevier Ltd. All rights reserved.