Diode laser heat treatment of lithium manganese oxide films

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• 作者：J. Prö ; ll^a ; ^{johannes.proell@kit.edu} ; R. Kohler^a ; A. Mangang^a ; S. Ulrich^a ; M. Bruns^a ; H.J. Seifert^a ; W. Pfleging^a ; ^b
• 关键词：Laser annealing ; Thin film crystallization ; Lithium-ion battery ; Lithium manganese oxide ; Surface reaction layer
• 刊名：Applied Surface Science
• 出版年：2012
• 期刊代码：6_01694332
• 类别：ms
• 出版时间：1 April, 2012
• 卷：258
• 期：12
• 页码：5146-5152
• 文件大小：1123 K

摘要

The crystallization of lithium manganese oxide thin films prepared by radio frequency magnetron sputtering on stainless steel substrates under 10 Pa argon pressure is demonstrated by a laser annealing technique. Laser annealing processes were developed as a function of annealing time and temperature with the objective to form an electrochemically active lithium manganese oxide cathode. It is demonstrated, that laser annealing with 940 nm diode laser radiation and an annealing time of 2000 s at 600 掳C delivers appropriate parameters for formation of a crystalline spinel-like phase. Characteristic features of this phase could be detected via Raman spectroscopy, showing the characteristic main Raman band at 627 cm^鈭?. Within cyclic voltammetric measurements, the two characteristic redox pairs for spinel lithium manganese oxide in the 4 V region could be detected, indicating that the film was well-crystallized and de-/intercalation processes were reversible. Raman post-analysis of a cycled cathode showed that the spinel-like structure was preserved within the cycling process but mechanical degradation effects such as film cracking were observed via scanning electron microscopy. Typical features for the formation of an additional surface reaction layer could be detected using X-ray photoelectron spectroscopy.