Application Of Ti₃C₂ MXene And NiCo-LDH Nanohybrid Materials In Anode Materials For Lithium Ion Batteries

The first member of the MXene family was first obtained from the precursor Ti₃AlC₂by the chemical method of HF etching by Professor Yuri Gogotsi's research group in 2011.As a new two-dimensional material,it has attracted wide attention in the field of energy conversion and storage.As one of the most popular two-dimensional materials,Ti₃C₂MXene has shown broad application prospects in the field of lithium ion anode materials due to its unique microstructure and physicochemical properties.At present,to develop more potential new MXenes based nanocomposites used in lithium ion battery anode to meet rising social demand is still the priority.In this project,a nano flower-like nickel/cobalt-layered double hydroxides?NiCo-LDH?with a layer thickness of 30.2 nm was first prepared.The?-phase with a layer spacing of4.6?was the main phase,and the?-phase with a layer spacing of 8.1?was the secondary phase.The low conductivity and fragile structure make it extremely unsatisfactory as a negative electrode material in terms of rate and cycle performance.Subsequently,pure?-phase and pure?-phase NiCo-LDH were prepared by the ion concentration control method.The?-phase with a large interlayer distance has better conductivity and is more conducive to alleviating the volume expansion of the lithium ion intercalation-deintercalation processes.Next,single-layer or few-layer Ti₃C₂ MXene nanosheet was prepared by HCl+LiF.Then,electrostatic attraction was used to induce the reaction of Ni²⁺and Co²⁺on the surface of Ti₃C₂ MXene to obtain NiCo-LDH/Ti₃C₂ nanohybrid material.This strategy of limiting the reaction can effectively reduce the thickness of the NiCo-LDH sheet,a 5?m ultra-thin,bended,wrinkled NiCo-LDH.The introduction of highly conductive MXene can suppress the structural degradation of NiCo-LDH to obtain a pure?-phase NiCo-LDH,the presence of NiCo-LDH also inhibits the stacking of MXene sheets to further improve the diffusion of ions and the efficiency of charge transfer.XPS shows that NiCo-LDH is firmly anchored on the surface of Ti₃C₂ MXene by strong interaction forces of Ti-O and O-C=O.Exhibits excellent rate performance as a lithium-ion battery anode(at a current density of 0.1 A g^-1,the specific capacity is 1076.7 mAh g^-1,and at a current density of 10 A g^-1,the specific capacity is 370.6 mAh g^-1)and excellent cycle life(800 cycles without attenuation at a current density of 5 A g^-1).Further more we explored the electrode morphology and its electrochemical behavior.Finally,a series of density functional theory calculations were used to further analyze the intercalation-deintercalation of lithium ions.It was proved that the introduction of Ti₃C₂MXene is beneficial to the rate performance and stability of NiCo-LDH/Ti₃C₂ anode materials.Combining theoretical calculations and experimental results,the excellent performance at high current density indicates that NiCo-LDH/Ti₃C₂ has broad application prospects in the field of lithium ion anode materials.