High-Energy Layered Oxide Cathodes with Thin Shells for Improved Surface Stability

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• 作者：Hyung-Joo Noh ; Seung-Taek Myung ; Yun Jung Lee ; Yang-Kook Sun
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：October 28, 2014
• 年：2014
• 卷：26
• 期：20
• 页码：5973-5979
• 全文大小：528K
• ISSN：1520-5002

文摘

Core鈥搒hell, nickel-rich layered oxide materials with a full concentration gradient (FCG) core and thin shells with low nickel content have been investigated. Hierarchically structured core鈥搒hell materials have the same FCG core, where the composition gradually changes from Li[Ni_0.86Co_0.07Mn_0.07]O₂ to Li[Ni_0.67Co_0.09Mn_0.24]O₂ from the center to the outer surface. A thin shell composed of either Li[Ni_0.48Co_0.26Mn_0.26]O₂ or Li[Ni_0.56Co_0.18Mn_0.26]O₂ was applied to the outer surface of the FCG core. This hierarchical core鈥搒hell structure efficiently integrates the benefit of high energy from the Ni-rich core, structural stability and favorable transport of Li⁺ ions from the FCG core, and surface stability from the low-Ni and high-Mn shell. The core鈥搒hell cathodes demonstrate improved cycling performance at 55 掳C even up to 4.5 V when compared to the FCG core-only cathode. Shells of low nickel content and a thickness of 鈭?00 nm provide sufficient surface stability, particularly at elevated temperatures. We suggest this novel core鈥搒hell structure as a suitable cathode for power sources such as electric vehicles, where safety and energy density are equally important.