Disproportionation in Li鈥揙2 Batteries Based on a Large Surface Area Carbon Cathode

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• 作者：Dengyun Zhai ; Hsien-Hau Wang ; Junbing Yang ; Kah Chun Lau ; Kaixi Li ; Khalil Amine ; Larry A. Curtiss
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：October 16, 2013
• 年：2013
• 卷：135
• 期：41
• 页码：15364-15372
• 全文大小：606K
• 年卷期：v.135,no.41(October 16, 2013)
• ISSN：1520-5126

文摘

In this paper we report on a kinetics study of the discharge process and its relationship to the charge overpotential in a Li鈥揙₂ cell for large surface area cathode material. The kinetics study reveals evidence for a first-order disproportionation reaction during discharge from an oxygen-rich Li₂O₂ component with superoxide-like character to a Li₂O₂ component. The oxygen-rich superoxide-like component has a much smaller potential during charge (3.2鈥?.5 V) than the Li₂O₂ component (4.2 V). The formation of the superoxide-like component is likely due to the porosity of the activated carbon used in the Li鈥揙₂ cell cathode that provides a good environment for growth during discharge. The discharge product containing these two components is characterized by toroids, which are assemblies of nanoparticles. The morphologic growth and decomposition process of the toroids during the reversible discharge/charge process was observed by scanning electron microscopy and is consistent with the presence of the two components in the discharge product. The results of this study provide new insight into how growth conditions control the nature of discharge product, which can be used to achieve improved performance in Li鈥揙₂ cell.