| Two-dimensional transition metal carbide,named MXene,recently has attracted considerable attention in the field of lithium-ion batteries by researchers due to its high conductivity,excellent hydrophilicity,tunable surface function group and adjustable structure.However,suffering from the low theoretical capacity and the restacking of the nanosheets seriously,which limits their practical application.MXene was used as a matrix material compound with the transition metal oxides(TMOs)or transition metal dichalcogenides,can not only improve the low capacity and prevent the layer stacking of MXene,but also improve the electronic conductivity of TMOs/TMDs thanks to the high conductivity of the MXene,and the Ti3C2 MXene can buffer volume expansion of the TMOs/TMDs.achieve a win-win effect.In this paper,to obtain MXene-based negative electrode materials for high-performance lithium-ion batteries,SnO2/MXene heterogeneous composite materials and ZnS/MXene composite materials with excellent lithium storage properties were prepared by strategies such as electrostatic self-assembly and organic liquid phase low temperature vulcanization,respectively.In addition,With the goal for adjusting the structure of two-dimensional MXene into three-dimensional structure,a high-performance three-dimensional porous MXene/rGO composite aerogel material was fabricated using a three-dimensional graphene gel as the backbone.(1)The 0D-2D SnO2 QDs/MXene nanocomposites are constructed by self-assembling the positively charged SnO2 quantum dots(SnO2 QDs)on the surface of the MXene nanosheets by electrostatic self-assembly,which can significantly improve the conductivity of the composites and buffer the volume strain of the SnO2 QDs during lithium storage.In addition,SnO2 QDs as interlayer particles can also inhibit the stacking of MXene sheet layers,facilitating the diffusion of ions and electron transport at the electrode interface,thereby improving the lithium storage performance of SnO2 QDs/MXene nanocomposites.When the current density is 100 mA g-1,after 100 cycles,a specific capacity of 659.8 mAh g-1 is remained.at a current density of 100 mA g-1,with a capacity retention rate of 91%,and a remained specific capacity of 364.0 mAh g-1 when the current density is 3 A g-1.exhibiting excellent specific capacity,multiplication performance and cycling stability.(2)Organic liquid phase low temperature vulcanization was used to obtain 0D-2D ZnS quantum dots(QDs)/MXene nanocomposites with the ZnS QDs was grown in situ on the two-dimensional MXene nanosheets.The ultra-small ZnS QDs obtained by vulcanization with ZIF-8 as the precursor can effectively reduce the absolute volume expansion during the charge/discharge process.In addition,using MXene as a matrix material for 0D ZnS can improves the electrical conductivity of the ZnS QDs/MXene composite and alleviates the problem of interparticle agglomeration.Thus,the 0D-2D ZnS QDs/MXene nanocomposite exhibits excellent cycling and multiplication performance after 500 cycles at a current density of 500 mA g-1 and still has 252.5 mAh g-1 at the 2 A g-1 when used as an anode for lithium-ion batteries.(3)Graphene oxide can be gelled and self-assembled under low temperature hydrothermal conditions to obtain a graphene gel 3D conductive skeleton structure,and MXene can be induced to grow on the constructed 3D graphene surface to obtain a 3D MXene/rGO composite aerogel material with high specific surface area and well-developed hole structure.This shift from two-dimensional to three-dimensional structure not only improves the utilization of MXene surface active sites,but also facilitates ion diffusion and electron transport during electrochemical reactions,making the three-dimensional MXene/rGO composite has a specific capacity of 628.0 mAh g-1 When the materials at the current density of 100 mA g’1 after 200 cycles,and a specific capacity of 186.1 mAh g-1when the current d-nsity is 10 A g-1,showing excellent electrochemical lithium storage performance. |
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