Preparation And Lithium Storage Properties Of Titanium Carbide Modified Iron Oxide And Molybdenum Sulfide Composites

Lithium ion battery has become the most popular energy storage devices because of its high energy density,high working voltage and long service life.Among them,the anode material plays an important role in lithium-ion batteries.At present,the theoretical specific capacity of commercial graphite anode is only 372 mAh g^-1,which is difficult to satisfy the requirements of high capacity energy storage equipment.Therefore,developing those anode materials with high specific capacity and long cycle life becomes the focus in recently research.The transition metal oxides and sulfides show high theoretical specific capacity as anode material for lithium-ion battery.However,in practical application,they show low conductivity and large volume expansion in the charge and discharge process,which will cause the damage of electrode structure.The problem can be solved by designing nano-sized materials and effective carbon coating.Two-dimensional layered Ti₃C₂T_x MXene,has good conductivity and low diffusion barrier of Li⁺.The adjustable layer spacing and rich functional groups on its surface make it easy to composite with other active materials.In this work,the Ti₃C₂T_x modified Fe₃O₄ or MoS₃ composites were prepared using Fe₃O₄ or MoS₃ as the main active materials,and Ti₃C₂T_x as the conductive substrate.As anode materials,these composites obtained excellent lithium storage performance.The main contents of this paper and experimental results are as follows:1.The cluster-like Fe₃O₄ nanospheres were prepared by solvothermal method.And the Ti₃C₂T_x was prepared and exfoliated to obtain few layered Ti₃C₂T_x?s-Ti₃C₂T_x?.Ultrasonic and freeze-drying methods were used to composite s-Ti₃C₂T_x and Fe₃O₄.We obtained four s-Ti₃C₂T_x/Fe₃O₄ composites by adjusting the relative contents of s-Ti₃C₂T_x.As anode materials,all of these s-Ti₃C₂T_x/Fe₃O₄ composites show superior lithium storage performance to the single Ti₃C₂T_x and Fe₃O₄.The composite with weight ratio of Ti₃C₂T_x nanosheets and Fe₃O₄?1:1?exhibits a high lithium storage capacity of 326.6 mAh g^-11 after1000 cycles at the high current density of 2 A g^-1,which is attributed to the synergistic effect of s-Ti₃C₂T_x and Fe₃O₄.2.The Ti₃C₂T_x with expanded layer spacing?alk-Ti₃C₂T_x?and MoS₃ composite?alk-Ti₃C₂T_x/MoS₃?was prepared by in situ one-step coprecipitation method,which used ammonium tetrathiomolybdate as molybdenum source and LiOH treated Ti₃C₂T_x as conductive substrate.Meanwhile,Ti₃C₂T_x/MoS₃ and s-Ti₃C₂T_x/MoS₃ composites were prepared by the same method in the same condition.The electrochemical results show that alk-Ti₃C₂T_x/MoS₃ composite as anode material exhibits the best lithium storage performance among these three composites,which is significantly better than single alk-Ti₃C₂T_x or MoS₃.The alk-Ti₃C₂T_x/MoS₃ can retain the high specific capacity of 507mAh g^-11 after 1000 cycles at the high current density of 2A g^-1.The excellent lithium storage performance is attributed to the stable structure of alk-Ti₃C₂T_x/MoS₃ and the synergistic effect of alk-Ti₃C₂T_x and MoS₃.