Structural Transformation of MXene (V2C, Cr2C, and Ta2C) with O Groups during Lithiation: A First-Principles Investigation

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• 作者：Dandan Sun ; Qianku Hu ; Jinfeng Chen ; Xinyu Zhang ; Libo Wang ; Qinghua Wu ; Aiguo Zhou
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：January 13, 2016
• 年：2016
• 卷：8
• 期：1
• 页码：74-81
• 全文大小：431K
• ISSN：1944-8252

文摘

For high capacities and extremely fast charging rates, two-dimensional (2D) crystals exhibit a significant promising application on lithium-ion batteries. With density functional calculations, this paper systematically investigated the Li storage properties of eight 2D M₂CO₂ (M = V, Cr, Ta, Sc, Ti, Zr, Nb, and Hf), which are the recently synthesized transition-metal carbides (called MXenes) with O groups. According to whether the structural transformation occurs or not during the adsorption of the first Li layer, the adsorption of Li can be grouped into two types: V-type (V₂CO₂, Cr₂CO₂, and Ta₂CO₂) and Sc-type (Sc₂CO₂, Ti₂CO₂, Zr₂CO2, Nb₂CO₂, and Hf₂CO₂). The structural transformation behaviors of V-type are reversible during lithiation/delithiation and are confirmed by ab initio molecular dynamic simulations. Except for Nb-MXene, the V-type prefers the sandwich H2H1T-M₂CO₂Li₄ structure and the Sc-type prefers the TH1H2-M₂CO₂Li₄ structure during the adsorption of the second Li layer. The H2H1T-M₂CO₂Li₄ structure of O layer sandwiched by two Li layers preferred by V-type can prevent forming Li dendrite and therefore stabilize the lithiated system. The tendency of O bonding to Li rather than M in V-type is bigger than that in Sc-type, which causes that the sandwich structure of H2H1T-M₂CO₂Li₄ is more suitable for V-type than Sc-type.