Ultrathin Lithium-Ion Conducting Coatings for Increased Interfacial Stability in High Voltage Lithium-Ion Batteries

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• 作者：Joong Sun Park ; Xiangbo Meng ; Jeffrey W. Elam ; Shiqiang Hao ; Christopher Wolverton ; Chunjoong Kim ; Jordi Cabana
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：May 27, 2014
• 年：2014
• 卷：26
• 期：10
• 页码：3128-3134
• 全文大小：377K
• 年卷期：v.26,no.10(May 27, 2014)
• ISSN：1520-5002

文摘

Ultrathin conformal coatings of the lithium ion conductor, lithium aluminum oxide (LiAlO₂), were evaluated for their ability to improve the electrochemical stability of LiNi_0.5Mn_1.5O₄/graphite Li-ion batteries. Electrochemical impedance spectroscopy confirmed the ion conducting character of the LiAlO₂ films. Complementary simulations of the activation barriers in these layers match experimental results very well. LiAlO₂ films were subsequently separately deposited onto LiNi_0.5Mn_1.5O₄ and graphite electrodes. Increased electrochemical stability was observed, especially in the full cells, which was attributed to the role of the coatings as physical barriers against side reactions at the electrode鈥揺lectrolyte interface. By comparing data from full cells where the coatings were applied to either electrode, the dominating failure mechanism was found to be the diffusion of transition metal ions from the cathode to the anode. The LiNi_0.5Mn_1.5O₄/graphite full cell with less than 1 nm LiAlO₂ on the positive electrode exhibited a discharge capacity of 92 mAh/g at C/3 rate. The chemical underpinnings of stable performance were revealed by soft X-ray absorption spectroscopy. First, both manganese and nickel were detected on the graphite electrode surfaces, and their oxidation states were determined as +2. Second, the ultrathin coatings on the anode alone were found to be sufficient to significantly reduce this deleterious process.