Fabrication And Electrochemical Performance Of Ti₃C₂T_x And Ti₃C₂T_x Composites

Renewable energy sources such as solar,hydro,and wind energy can alleviate environmental problems associated with potential depletion of fossil fuels and greenhouse gas emissions.However,due to large fluctuations in power generation,it is necessary to efficiently store the electricity generated by these renewable energy sources for on-demand supply.Among all kinds of energy storage devices,supercapacitors have attracted much attention because of their outstanding performance,and the electrode material is one of the key factors affecting its energy storage capacity.The two-dimensional transition metal carbide Ti₃C₂T_x is a new type of two-dimensional material discovered in recent years.Its performance is comparable to that of graphene,which has attracted great attention from researchers.The conventional method for preparing Ti₃C₂T_x is to etch Ti₃AlC₂ with hydrofluoric acid,but it is not conducive to mass production because it requires a long time of etching.In this work,the etching time can be effectively reduced by ball milling and hydrofluoric acid etching.In addition,Ti₃C₂T_x has a high electrical conductivity,but the specific capacity is not high,the interlayer spacing is small and easy to stack.In response to these problems,this work also combined Ti₃C₂T_x with MoS₂ and CoNiO₂ to prepare MoS₂/Ti₃C₂T_x and CoNiO₂/Ti₃C₂T_x composites with good electrochemical energy storage characteristics.The main contents include the following aspects:?1?Ti₃C₂T_x was prepared by HF etching of ball-milled Ti₃AlC₂ powder.The effects of etching temperature and milling time on the preparation and electrochemical performance of Ti₃C₂T_x were studied in detail.Studies have shown that higher etching temperatures and longer ball milling times accelerate the transition from Ti₃AlC₂ to Ti₃C₂T_x.At the same time,the ball milling treatment can improve the specific capacity of Ti₃C₂T_x.The sample?M12-E60?12??after ball milling Ti₃AlC₂ for 12 h and HF etching at 60°C for 12h exhibits the best electrochemical performance with the specific capacitance of 56.2 F/g at current density of 0.5 A/g,and the capacitance retention of M12-E60?12?is 95%at the end of 3000cycles.?2?H-MoS₂/Ti₃C₂T_x and K-MoS₂/Ti₃C₂T_x composite materials were prepared by combining Ti₃C₂T_x with MoS₂ of flowers or blocks morphologies which is obtained by using a molybdenum source of MoO₃ and two sulfur sources of thiourea and thioacetamide.The preparation method is a one-step hydrothermal method.The effect of MoS₂ content on the electrochemical properties of two composites was further investigated.The results show,the interlayer spacing of Ti₃C₂T_x increases after compounding.The specific capacity of composites is increased to different extents compared with single Ti₃C₂T_x,and the rate performance of composites is also improved compared with single MoS₂.The specific capacity of H-MoS₂/Ti₃C₂T_x?H-?1:3??when the mass ratio of Ti₃C₂T_x to MoO₃ is 1:3 can reach 240 F/g at 0.5 A/g,while for K-MoS₂/Ti₃C₂T_x?K-?2:3??when the mass ratio of Ti₃C₂T_x to MoO₃ is 2:3,the specific capacity is 204 F/g,which may be attributed to the synergy between MoS₂ and Ti₃C₂T_x makes the electrode material have good electrochemical energy storage characteristics.?3?The precursor complex with cobalt source and nickel source was prepared by co-precipitation method at room temperature,and calcined at 300°C to prepare CoNiO ₂nanoparticles after dried under vacuum.The CoNiO₂/Ti₃C₂T_x composite was then obtained by co-precipitation.The effect of CoNiO₂ content on the electrochemical properties of CoNiO₂/Ti₃C₂T_x composites was investigated.The results show,the interlayer spacing of Ti₃C₂T_x increases after compounding.Compared with single Ti₃C₂T_x or CoNiO₂,CoNiO₂/Ti₃C₂T_x has a larger specific capacity.the 2-CoNiO₂/Ti₃C₂T_x composite of 2 mmol cobalt source has a specific capacity of 389 F/g at a current density 1 A/g;The specific capacity is 271 F/g at 20 A/g;After 1500 cycles of charge and discharge,the specific capacity of 2-CoNiO₂/Ti₃C₂T_x is only attenuated by 19%.Therefore,the 2-CoNiO₂/Ti₃C₂T_x composite has good specific capacity,rate performance and cycle stability.