Electroactive separator for high voltage graphite/LiNi_0.5Mn_1.5O₄ lithium ion batteries

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• 作者：K.W. Leitner ; H. Wolf ; A. Garsuch ; F. Chesneau ; M. Schulz-Dobrick
• 关键词：High voltage cathode ; LiNi0.5Mn1.5O4 ; Spinel ; Standard electrolyte ; Separator ; Lithium titanate
• 刊名：Journal of Power Sources
• 出版年：2013
• 出版时间：15 December, 2013
• 年：2013
• 卷：244
• 期：Complete
• 页码：548-551
• 全文大小：1053 K

文摘

The interaction of charged LiNi_0.5Mn_1.5O₄ cathodes in contact with standard electrolyte solvents as e.g. ethylene carbonate and ethyl methyl carbonate is investigated. Due to the high electrochemical potential of the charged LiNi_0.5Mn_1.5O₄ cathode electrolyte decomposition occurs, which results in the formation of gases and other compounds. The corresponding decomposition products are successfully detected and analyzed by means of gas chromatography. We propose that decomposition products react on the surface of the graphite anode, which leads to strong capacity fading. Therefore, an electrochemically active separator containing Li_4+xTi₅O₁₂ is used in graphite/LiNi_0.5Mn_1.5O₄ cells in order to scavenge and neutralize these decomposition products as well as soluble transition metal ions. This separator most probably prevents the migration of decomposition products to the anode and their subsequent reaction on the anode surface. Pouch cells with graphite anode, LiNi_0.5Mn_1.5O₄ cathode, standard electrolyte and the Li_4+xTi₅O₁₂ based separator are cycled successfully for hundreds of cycles without any significant capacity fading. In contrast, similar cells equipped with a conventional separator show strong degradation.