Fabrication And Electrochemical Performance Of Ti₃C₂ Compsites

As one of the most promising energy storage devices,lithium ion battery?LIBs?has the advantages of high energy density,long cycle life and small self-discharge.In recent years,as the rapid development of electronic devices,such as mobile phones,computers and electric vehicles,the power density and energy density of LIBs have needed to be further improved.Recently,a new type of two-dimensional layered materials MXene has attracted wide attention in energy storage field due to its unique layered structure and excellent lithium storage performance.However,the electrochemical performance of multi-layer Ti₃C₂ is unsatisfactory due to the relatively low theoretical specific capacity and the characteristics of the stack.To solve above-mentioned problems,a series of composites containing Ti₃C₂ and metal oxide were synthesized to improve the specific capacity and cycling stability of LIBs.XRD,SEM,EDS and electrochemical tests were used to characterize and test the composite materials,and the synthesis mechanism of the materials and the reasons for the excellent performance of the cathode materials were discussed.The main contents of this paper are as follows:?1?Using the alkali oxidation method to oxidize Ti₃C₂ in the aqueous alkali at the normal temperature and calcination,TiO₂ nw/Ti₃C₂?TiO₂ nanowire/Ti₃C₂?nanocomposite was obtained.As a result,uniform and fine lead TiO₂ nw were grown in-situ in the matrix Ti₃C₂ successfully,which promotes the transfer of charge and ion,improves the specific surface area and effectively prevents the Ti₃C₂ layer from stacking.At the same time,C increases the conductivity of the material,which is conducive to the embedding and removal of lithium ions during the charge and discharge process.When the Ti O₂ nw/Ti₃C₂ composite material is used as electrode material,it shows a good performance of lithium electrochemical storage.The initial discharge capacity reached 768.7 mAh/g.After the charge and discharge 200 times,the capacity remained stable at 216.4mAh/g,which was more than twice that of Ti₃C₂ electrode materials.?2?In order to improve the specific capacity of composite materials,The CoO/Ti₃C₂ nanocomposite was obtained by the hydrothermal method with CoCO₃/Ti₃C₂ composite as the precursor.The CoO/Ti₃C₂ nanocomposite,formed by the electrostatic adsorption,had a uniform size and a mesoporous structure.When the CoO/Ti₃C₂ nanocomposite was used as anode materials for LIBs,the capacities was up to 320 mAh/g after 100 cycles under a current rate of100 mA/g,which is higher than that of Ti₃C₂?120 mAh/g?.This superior performance was attributed to the unique three-dimensional structure composite materials with higher specific surface area,which can provide more lithium storage locations.?3?CoO ball/Ti₃C₂ nanocomposite material has been successfully prepared by a one-step solvothermal method.The introduction of CoO nanosphere can increase the specific surface area the layer spacing of the material,that were good for lithium ion intercalated.meanwhile,The close contact between the CoO nanoparticles and the high conductivity two-dimensional Ti₃C₂ buffered the volume change the improved utilization of active material in the process of charge-discharge for lithium ion battery electrodes.The first charge capacity and discharge capacity were 456 mAh/g and 915 mAh/g respectively,and after 300cycles at a current rate of 100mA/g,It still can obtain a high reversible specific capacity of 415 mAh/g.