Yao Long, Gu Qinfen, Yu Xuebin
Department of Materials Science, Fudan University, Shanghai 200433, China.
Australian Synchrotron, ANSTO, 800 Blackburn Road, Clayton, 3168, Australia.
ACS Nano. 2021 Feb 23;15(2):3228-3240. doi: 10.1021/acsnano.0c09898. Epub 2021 Jan 28.
MXene combining high metal-like conductivity, high hydrophilicity, and abundant surface functional groups has been recognized as a class of versatile two-dimensional materials for many applications. However, the aggregation of MXene nanosheets from interlayer van der Waals force and hydrogen bonds represents a major problem that severely limits their practical use. Here, we report an aerogel structure of MOFs@MXene, in which the formed MOF particles can effectively prevent the accumulation of MXene, enabling a three-dimensional (3D) hierarchical porous conductive network to be composed with an ultralight feature. Subsequently, a 3D porous MXene aerogel threaded hollow CoS nanobox composite ((CoS NP@NHC)@MXene) derived from the MOFs@MXene aerogel precursor was synthesized, and the highly interconnected MXene network and hierarchical porous structure coupled with the ultrafine nanocrystallization of the electrochemically active phase of CoS yield the hybrid system with excellent electron and ion transport properties. Benefiting from the synergistic effect of the components, the (CoS NP@NHC)@MXene composite manifests outstanding electrochemistry properties as electrode materials for all of the lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and potassium-ion batteries (PIBs). It demonstrated the excellent cycle stability and high capacities of 1145.9 mAh g at 1 A g after 800 cycles and 574.1 mAh g at 5 A g after 1000 cycles for LIBs, 420 mAh g at 2 A g after 650 cycles for SIBs, and 210 mAh g at 2 A g after 500 cycles for PIBs. First-principle calculations confirmed that the (CoS NP@NHC)@MXene hybrid could enhance the charge transfer reaction kinetics, particularly at the interface. More importantly, the excellent rate performance under high mass loading and the high volumetric energy and power density of the entire electrode represent the potential of (CoS NP@NHC)@MXene composites for applications to practical electrochemical energy storage devices. The synthesis method reported in this Article is versatile and can be easily extended to produce other porous MXene-aerogel-based materials for various applications.
MXene具有高金属样导电性、高亲水性和丰富的表面官能团，已被公认为是一类适用于多种应用的多功能二维材料。然而，MXene纳米片因层间范德华力和氢键而发生聚集，这是一个严重限制其实际应用的主要问题。在此，我们报道了一种MOFs@MXene气凝胶结构，其中形成的MOF颗粒可以有效防止MXene的聚集，从而形成具有超轻特性的三维（3D）分级多孔导电网络。随后，合成了一种由MOFs@MXene气凝胶前驱体制备的3D多孔MXene气凝胶穿线中空CoS纳米盒复合材料（(CoS NP@NHC)@MXene），高度互连的MXene网络和分级多孔结构，再加上CoS电化学活性相的超细纳米晶化，产生了具有优异电子和离子传输性能的混合体系。受益于各组分的协同效应，(CoS NP@NHC)@MXene复合材料作为锂离子电池（LIB）、钠离子电池（SIB）和钾离子电池（PIB）的电极材料，表现出出色的电化学性能。对于LIB，它在800次循环后1 A g下表现出优异的循环稳定性和1145.9 mAh g的高容量，在1000次循环后5 A g下表现出574.1 mAh g的高容量；对于SIB，在650次循环后2 A g下表现出420 mAh g的高容量；对于PIB，在500次循环后2 A g下表现出210 mAh g的高容量。第一性原理计算证实，(CoS NP@NHC)@MXene杂化物可以增强电荷转移反应动力学，特别是在界面处。更重要的是，在高质量负载下的优异倍率性能以及整个电极的高体积能量和功率密度，代表了(CoS NP@NHC)@MXene复合材料应用于实际电化学储能装置的潜力。本文报道的合成方法具有通用性，可以很容易地扩展以制备用于各种应用的其他多孔MXene气凝胶基材料。
