交联网络结构Ti_(3)C_(2)纳米线的制备及其在锂硫电池中的应用  

Preparation of Ti_(3)C_(2)nanowires with cross-linked network structure and its application in lithium-sulfur batteries

作　　者：张锦 李嘉琪 岳文博 Jin Zhang;Jiaqi Li;Wenbo Yue(Beijing Key Laboratory of Energy Conversion and Storage Materials,College of Chemistry,Beijing Normal University,Beijing 100875,China)

机构地区：[1]北京师范大学化学学院,能量转换与储能北京市重点实验室,北京100875

出　　处：《科学通报》2022年第20期2431-2440,共10页Chinese Science Bulletin

基　　金：国家自然科学基金(21975030)资助。

摘　　要：锂硫电池因其能量密度高、成本低等优势被认为是最具希望的下一代储能器件之一,然而其正极材料的发展和应用仍面临诸多挑战.本文通过将剥离的Ti_(3)C_(2)纳米片在NaOH溶液中刻蚀得到具有交联结构的Ti_(3)C_(2)纳米线,并利用熔融浸渍法负载硫颗粒,用作锂硫电池的正极材料.具有极性表面的Ti_(3)C_(2)可有效捕获多硫化锂中间体,从而抑制多硫化锂的穿梭效应.与Ti_(3)C_(2)纳米片相比,具有交联网络状结构的Ti_(3)C_(2)纳米线具有更大的比表面积和多孔结构,可以有效提供固硫所需的空间,并容纳硫在锂化过程中的体积膨胀.其较大的比表面积有利于Ti_(3)C_(2)纳米线对多硫化锂的捕获,其多孔结构有利于锂离子的扩散.Ti_(3)C_(2)纳米线/硫复合物展现出优异的电化学性能,在0.2 C的倍率下,100次循环后,其可逆容量为658 mAh g^(−1);在1 C倍率下,300次循环后,Ti_(3)C_(2)纳米线/硫复合物仍能保持436 mAh g^(−1)的可逆容量.Lithium-sulfur batteries are considered as one of the most promising next-generation energy storage devices due to their high energy density and low cost,but their development and application still face many challenges such as the shuttle effect of lithium polysulfide.Recently,a new type of two-dimensional material,MXene(e.g.,Ti_(3)C_(2)),has attracted much attention.The high specific surface area,high electrical conductivity and polar surface of Ti_(3)C_(2)make it an ideal sulfur host for lithium-sulfur batteries.However,two-dimensional Ti_(3)C_(2)nanosheets(Ti_(3)C_(2)-NS)are easy to aggregate together,which reduces the contact area between them and sulfur,and results in the performance degradation of the sulfur electrode.In this work,Ti_(3)C_(2)nanowires(Ti_(3)C_(2)-NW)with cross-linked structure are successfully synthesized by etching the exfoliated Ti_(3)C_(2)nanosheets in NaOH solution.Subsequently,sulfur-loaded Ti_(3)C_(2)-NW(Ti_(3)C_(2)-NW@S)is prepared by the melt-impregnation method and used as the positive electrode material for lithium-sulfur batteries.Scanning electron microscope(SEM)and transmission electron microscope(TEM)images show that Ti_(3)C_(2)-NW is composed of cross-liked nanowires with a width of 5–10 nm,and sulfur particles are successfully loaded in the cross-linked network structure of Ti_(3)C_(2)-NW.Moreover,the EDX element mapping images show that the elemental distribution of S is consistent with those of C,O and Ti,further confirming the high dispersion of sulfur particles in Ti_(3)C_(2)-NW.Subsequently,Ti_(3)C_(2)-NW is characterized by using nitrogen adsorption and desorption technique.The type IV isotherm indicates that Ti_(3)C_(2)-NW has a mesoporous structure and its specific surface area is 124.6 m2 g−1.XPS analysis proves the interaction between Ti atoms on the surface of Ti_(3)C_(2)-NWand S atoms from sulfur particles because of the presence of Ti-S peak in the high-resolution Ti 2p and S 2p XPS spectra.The loading of sulfur in Ti_(3)C_(2)-NW@S(~71 wt%)is determined by t

关 键 词：Ti_(3)C_(2)纳米线 交联网络结构 高比表面积 穿梭效应 锂硫电池 

分 类 号：TM912[电气工程—电力电子与电力传动] TB383.1[一般工业技术—材料科学与工程]