Aging of Li₂FeSiO₄ cathode material in fluorine containing organic electrolytes for lithium-ion batteries

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• 作者：Christian Dippel ; Steffen Krueger ; Richard Kloepsch ; Philip Niehoff ; Bjoern Hoffmann ; Sascha Nowak ; Stefano Passerini ; Martin Winter ; Jie Li ; ^{jie.li@uni-muenster.de}
• 关键词：Lithium-ion battery ; LiPF6 ; LiBF4 electrolyte ; Li2FeSiO4 cathode ; Aging
• 刊名：Electrochimica Acta
• 出版年：2012
• 出版时间：15 December, 2012
• 年：2012
• 卷：85
• 期：Complete
• 页码：66-71
• 全文大小：870 K

文摘

The stability vs. aging of Li₂FeSiO₄ (LFS) cathode material in fluorine-based electrolytes, especially at elevated temperature, was studied in this work. The LFS powder was initially synthesized using a hydrothermal route and then aged at 60 ¡ãC for 40 days in LiPF₆ and LiBF₄-based electrolytes. The residual powder and the electrolyte were investigated afterwards. In the case of LiPF₆, a structural and compositional change of LFS to Li₂SiF₆ was observed by XRD. SEM images confirmed that this change led to a morphology change of the aged material. XPS, EDX and ICP-OES measurements showed a large increase of fluorine content inside the residual powder. NMR investigations indicated an accelerated decomposition of electrolyte in the presence of LFS compared to the electrolyte aged without LFS. Our results suggest a degradation of LFS to Li₂SiF₆ in the fluorine-based electrolyte at elevated temperatures while the electrolyte decomposition is accelerated.