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MXenes: A New Family of Two-Dimensional Materials and its Application as Electrodes for Li-ion Batteries.

机译：MXenes：一种新型的二维材料及其在锂离子电池电极中的应用。

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摘要

Two-dimensional, 2D, materials, such as graphene, possess a unique morphology compared to their 3D counterparts, from which interesting and novel properties arise. Currently, the number of non-oxide materials that have been exfoliated is limited to two fairly small groups, viz. hexagonal, van der Waals bonded structures (e.g. graphene and BN) and layered transition metal chalcogenides.;The MAX phases are a well established family of layered ternary transition metal carbides and/or nitrides, with a composition of Mn +1AXn, where M is an early transition metal, A is one of A group elements, X is C and/or N; with n = 1, 2, or 3. The aim of this work is to exfoliate the MAX phases and produce 2D layers of transition metals carbides and/or nitrides by the selective etching of the A layers from the MAX phases. We labeled the resulting 2D M n+1Xn layers "MXenes" to emphasize the loss of the A group element from the MAX phases and the suffix "ene" to emphasize their 2D nature and their similarity to graphene.;The etching process was carried out using aqueous hydrofluoric acid at room temperature. Thirteen different MXenes were produced as a result of this work, viz., Ti2C, Nb2C, V2C, Mo2C, (Ti0.5,Nb0.5)2C, (Ti 0.5,V0.5)2C, Ti3C2, (Ti 0.5,V0.5)3C2, (V0.5,Cr 0.5)3C2, Ti3CN, Ta4C 3, Nb4C3 and (Nb0.5,V0.5) 4C3. The as-synthesized MXenes were terminated with a mixture of OH, O, and/or F groups. Sonicating MXenes resulted in separating the stacked layers to a small extent. When Ti3C2 was intercalated with dimethylsulfoxide, however, followed by sonication in water, large-scale delamination occurred, which resulted in aqueous colloidal solutions that could in turn be fabricated into MXene "paper".;MXenes were found to be electrically conductive, hydrophilic and stable in aqueous environments, a rare combination indeed, with huge potential in many applications, from energy storage, to sensors to catalysts. This work focused on the use of MXenes as electrode materials in Li-ion batteries. They exhibited excellent capability to handle high cycling rates with good gravimetric capacities. The lithiation and delithiation were found to be due to redox intercalation/deintercalation reactions.
机译：与3D对应物相比，二维2D材料（例如石墨烯）具有独特的形态，由此产生了有趣而新颖的特性。目前，已剥离的非氧化物材料的数量仅限于两个相当小的组。六角形，范德华键合结构（例如石墨烯和BN）和层状过渡金属硫族化物。MAX相是成熟的层状三元过渡金属碳化物和/或氮化物族，组成为Mn + 1AXn，其中M为早期过渡金属，A为A族元素之一，X为C和/或N； n = 1、2或3。这项工作的目的是剥离MAX相，并通过从MAX相中选择性刻蚀A层来产生过渡金属碳化物和/或氮化物的二维层。我们将所得的2D M n + 1Xn层标记为“ MXenes”，以强调MAX相中A组元素的损失，并标记后缀“ ene”，以强调其2D性质和与石墨烯的相似性。在室温下使用氢氟酸水溶液。这项工作的结果是产生了13种不同的MXene，即Ti2C，Nb2C，V2C，Mo2C，（Ti0.5，Nb0.5）2C，（Ti 0.5，V0.5）2C，Ti3C2，（Ti 0.5， V0.5）3C2，（V0.5，Cr 0.5）3C2，Ti3CN，Ta4C 3，Nb4C3和（Nb0.5，V0.5）4C3。合成后的MXenes用OH，O和/或F基团的混合物终止。对MXene进行超声处理可在较小程度上分离堆叠的层。但是，当Ti3C2插入二甲亚砜中，然后在水中进行声处理时，会发生大规模分层，从而导致胶体水溶液可以依次制成MXene“纸”。MXene被发现具有导电性，亲水性和在水环境中保持稳定，确实是一种罕见的组合，在从能量存储到传感器再到催化剂的许多应用中都具有巨大的潜力。这项工作的重点是将MXenes用作锂离子电池的电极材料。它们表现出了出色的能力，可以以良好的重量分析能力应对高循环速率。发现锂化和脱锂是由于氧化还原嵌入/脱嵌反应。

著录项

  • 作者

    Abdelmalak, Michael Naguib.;

  • 作者单位

    Drexel University.;

  • 授予单位 Drexel University.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 176 p.
  • 总页数 176
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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