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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Unraveling the Positive Roles of Point Defects on Carbon Surfaces in Nonaqueous Lithium-Oxygen Batteries
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Unraveling the Positive Roles of Point Defects on Carbon Surfaces in Nonaqueous Lithium-Oxygen Batteries

机译：阐明非水锂氧电池中碳表面上点缺陷的积极作用

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摘要

Carbon has been widely used to form cathodes for nonaqueous lithium-oxygen (Li-O-2) batteries due to its high specific surface area, high electrical conductivity, and cost-effectiveness. The mechanistic understanding of carbon materials, particularly the effect of carbon surface properties on the battery's performance, however, is limited. In this work, we perform first-principles calculations to study the roles of point defects on carbon surfaces. Five representative defective structures, including SV (single vacancy), DV5-8-5 (two pentagons and one octagon), DVSSS-777 (three pentagons and three heptagons), DVSSSS-6-7777 (four pentagons, one hexagon, and four heptagons), and SW (Stone-Wales) defects, are considered. On the basis of the adsorption energies of O-2 and Li, the different Li4O4 growing pathways on these structures are identified, and free energy diagrams are then obtained. It is found that the presence of DVS555-6-7777 and SW defects is beneficial to nonaqueous Li-O-2 batteries because (i) DVS555-6-7777 and SW defects exhibit zero-band-gap semiconductor behaviors, ensuring excellent electrical conductivity; (ii) DVSSSS-6-7777 and SW defects lead to a high discharge voltage but low charge voltage; DV5555-6-7777 and SW defects are stable during battery cycling and do not promote the formation of side product Li2CO3; and (iv) by using DMSO as a sample, DVS555-6-7777 and SW defects are not supposed to decompose electrolytes. Hence, carbon materials containing DVSSSS-6-7777 and SW defects are desired for nonaqueous Li-O-2 batteries.
机译：由于碳的高比表面积，高的电导率和成本效益，碳已被广泛用于形成非水锂氧（Li-O-2）电池的阴极。然而，对碳材料的机械理解，特别是碳表面性质对电池性能的影响是有限的。在这项工作中，我们执行第一性原理计算以研究点缺陷在碳表面上的作用。五种代表性缺陷结构，包括SV（单空位），DV5-8-5（两个五边形和一个八边形），DVSSS-777（三个五边形和三个七边形），DVSSSS-6-7777（四个五边形，一个六边形和四个）考虑了七边形）和SW（Stone-Wales）缺陷。根据O-2和Li的吸附能，确定了这些结构上不同的Li4O4生长途径，然后获得了自由能图。发现DVS555-6-7777和SW缺陷的存在对非水Li-O-2电池是有利的，因为（i）DVS555-6-7777和SW缺陷表现出零带隙半导体行为，从而确保了出色的导电性; （ii）DVSSSS-6-7777和SW缺陷导致高放电电压但低充电电压; DV5555-6-7777和SW缺陷在电池循环期间稳定，并且不会促进副产物Li2CO3的形成; （iv）通过使用DMSO作为样品，不应认为DVS555-6-7777和SW缺陷会分解电解质。因此，对于非水Li-O-2电池，期望包含DVSSSS-6-7777和SW缺陷的碳材料。

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