Interfacial Origin of Performance Improvement and Fade for 4.6 V LiNi0.5Co0.2Mn0.3O2 Battery Cathodes

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• 作者：Yu-Mi Lee ; Kyoung-Mo Nam ; Eui-Hyung Hwang ; Young-Gil Kwon ; Dong-Hyun Kang ; Sung-Soo Kim ; Seung-Wan Song
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 22, 2014
• 年：2014
• 卷：118
• 期：20
• 页码：10631-10639
• 全文大小：605K
• 年卷期：v.118,no.20(May 22, 2014)
• ISSN：1932-7455

文摘

The interfacial origin of performance improvement and fade of high-voltage cathodes of LiNi_0.5Co_0.2Mn_0.3O₂ for high-energy lithium-ion batteries has been investigated. Performance improvement was achieved through interfacial stabilization using 5 wt % methyl (2,2,2-trifluoroethyl) carbonate (FEMC) of fluorinated linear carbonate as a new electrolyte additive. Cycling with the FEMC additive at 3.0鈥?.6 V versus Li/Li⁺ results in the formation of a stable solid electrolyte interface (SEI) layer and effective passivation of cathode surface, leading to improved cycling performance delivering enhanced discharge capacities to 205鈥?82 mAhg^鈥? and capacity retention of 84% over 50 cycles. The SEI layer notably includes plenty of metal fluorides and 鈭扖F-containing species formed by additive decomposition. On the contrary, the origin of performance fade in electrolyte only was ineffective surface passivation and dissolution of metal elements, which leads to oxygen loss, surface structural degradation and crack formation at the LiNi_0.5Co_0.2Mn_0.3O₂ particles. The data provide a basic understanding of the interfacial stabilization mechanism on high-voltage layered oxide cathodes.