Preparation And Properties Of MXene-Based Electrode Material With High Mass Loading And High Areal Capacitance

The integration and miniaturization of energy devices in portable electronics require the flexible supercapacitors with high areal capacity.Also,a practical supercapacitor hopes a high mass loading to produce more energy storage.Nevertheless,despite of the potential high capacitance of MXene,most MXenes and MXene hybrids-based electrodes are still in“low”situation:low areal capacitance and/or low mass loading.This can be ascribed to limited ion transport in MXene flakes resulting from self-restacking or limited theoretical capacities of materials introduced to space MXene layers.To solve the above problems,this paper studied the representative Ti₃C₂ in MXene and prepared electrode materials with superior active mass loading and high areal capacitance.Two composites were obtained by cetyltrimethylammonium bromide(CTAB)assisted V₂O₅ intercalation into Ti₃C₂ MXene layers to prepare CT-Ti₃C₂@V₂O₅ and by one-step hydrothermal method to prepare Na₂Ti₃O₇ nanoribbon-decorated Ti₃C₂(Ti₃C₂@Na₂Ti₃O₇ hereinafter referred to as a-Ti₃C₂-150).The research contents are as follows:(1)Cetyltrimethylammonium bromide(CTAB)assisted V₂O₅ intercalation into Ti₃C₂ MXene layers.The precursor Ti₃Al C₂ was etched by HCl and LiF to obtain Ti₃C₂.Cationic surfactant CTAB was introduced to adsorbed negatively charged VO₃^-into Ti₃C₂ layers.After an annealing process,the CTAB-assisted V₂O₅ intercalated Ti₃C₂layers(CT-Ti₃C₂@V₂O₅)were obtained.The morphology and structure of CT-Ti₃C₂@V₂O₅ were characterized by Scanning Electron Microscope,Transmission Electron Microscope,X-Ray Diffraction Phase Analysis,X-Ray Photoelectron Spectrascopy indicating that V₂O₅ was successfully introduced into the Ti₃C₂ layer.The CT-Ti₃C₂@V₂O₅ electrode provides a specific capacitance of 2065 mF cm^-2 at a current density of 3 mA cm^-2 with superior active mass loading(15 mg cm^-2)and excellent cycle stability(capacitance retention of approximately 93%after 6000cycles).The Flexible all-solid-state supercapacitor(ASSS)based on CT-Ti₃C₂@V₂O₅delivers a high areal capacitance of 477 mF cm^-2 at 1 m V s^-1 and exhibits stable performance at different bending states.(2)One-step hydrothermal method to prepare Na₂Ti₃O₇ nanoribbon-decorated Ti₃C₂.The precursor Ti₃Al C₂ was etched by HF to obtain Ti₃C₂.The composite material of ribbon Na₂Ti₃O₇ on Ti₃C₂ was prepared by one-step hydrothermal method in Na OH aqueous solution.The morphology and structure of a-Ti₃C₂-150 were characterized by Scanning Electron Microscope,X-Ray Diffraction Phase Analysis,X-Ray Photoelectron Spectrascopy,which indicated that Na₂Ti₃O₇ was generated in situ on Ti₃C₂.The a-Ti₃C₂-150 electrode provides a specific capacitance of 1010.2 mF cm^-2 at a current density of 1 mA cm^-2 with superior active mass loading(15 mg cm^-2)and excellent cycle stability(capacitance retention of approximately 95%after 8000cycles).In this paper,two composites(CT-Ti₃C₂@V₂O₅ and a-Ti₃C₂-150)were prepared.By establishing a hierarchical structure,the electrochemical performance of the material is improved.This strategy can be extended to other materials hybridizing with MXenes for flexible high-performance supercapacitor electrodes.