Li2O2 Wetting on the (110) Surface of RuO2, TiO2, and SnO2: An Initiating Force for Polycrystalline Growth

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• 作者：W. T. Geng ; T. Ohno
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：January 15, 2015
• 年：2015
• 卷：119
• 期：2
• 页码：1024-1031
• 全文大小：365K
• ISSN：1932-7455

文摘

We report a first-principles study on the initial deposition of Li₂O₂ on three rutile oxide surfaces, RuO₂(110)-(1脳1)-O, TiO₂(110), and SnO₂(110). The intermediate discharge product in a Li鈥揳ir battery, LiO₂, is found to be less stable on all rutile surfaces and will be further reduced to Li₂O₂ through disproportionation reaction. For the first and second layers of deposited Li₂O₂, the adsorption energy is comparable to the cohesive energy of bulk Li₂O₂, suggesting Li₂O₂ will likely wet the oxide surfaces and grow into thin films rather than particles. Electronic structure analyses of interfaces demonstrate Li₂O₂/TiO₂(110) is metallic and Li₂O₂/SnO₂(110) is semiconducting with a bandgap of 0.2 eV, substantially smaller than in bulk Li₂O₂. The large lattice mismatch at these interfaces could create amorphousness of Li₂O₂ and grain boundaries might form abundantly thereafter, both of which can provide charge and ion transport channels needed for oxygen reduction and evolution reactions in Li鈥揳ir batteries. Therefore, coating nanostructured carbon cathode with thin films of TiO₂ or employing mesoporous TiO₂ nanostructures as cathode could possibly lead to the formation of low-resistance Li₂O₂ thin films and thereby enhance the rate capacity of Li鈥揳ir batteries.