Synthesis And Performance Study Of Halide Double Perovskite Anode Materials For Lithium-ion Batterie

In recent years,with the popularity of portable electronic devices and the rapid development of the field of electric vehicles,higher requirements have been put forward for the electrochemical performance of lithium ion batteries.However,halide perovskite materials have low activation energy,high ionic conductivity,and good defect tolerance.Due to their special lattice structure,Li⁺can enter its lattice gap without damaging the crystal structure.Therefore,halide perovskite materials have great potential application value in the field of negative electrode materials for lithium ion batteries.However,the existing halide perovskite anode materials for lithium ion batteries have poor cycle stability and lead content issues,which do not meet the concept of green,environmentally friendly and sustainable development.Therefore,it is crucial to develop a new type of lead-free perovskite anode material for lithium ion batteries with good cycle stability,high capacity,and environmental protection.The halide dicalcium titanium material is derived from the perovskite material,and a dicalcium titanium structure is formed by replacing Pb²⁺with monovalent and trivalent cations.The dicalcium titanium material not only removes Pb²⁺,making the material more green and environmentally friendly,but also retains the perovskite structure with excellent electrochemical performance,stronger structural tolerance,and more replaceable element types to regulate its electrochemical performance.In this paper,the lead-free double calcium titanium halide material Cs₂NaErCl₆ was first taken as the research object to determine the impact of Li⁺doping on its electrochemical performance and its lithium storage mechanism.On the basis of the lead free double calcium titanium halide material Cs₂NaErCl₆,a new type of layered double perovskite material Cs₄MnBi₂Cl₁₂ was developed as the anode material for lithium ion batteries,clarifying the positive effect of layered structure on battery performance and the lithium storage mechanism of Cs₄MnBi₂Cl₁₂,The application of halide double calcium titanium materials in the field of negative electrode materials for lithium ion batteries has been broadened,with the main contents as follows:（1）The halogenated double perovskite material Cs₂NaErCl₆ was synthesized by physical grinding method.Using the characteristic that Li⁺can enter the lattice gap of perovskite without damaging the lattice structure,different concentrations of Li⁺were doped into the double perovskite material.The effect of Li⁺doping on the electrochemical properties of the double perovskite material Cs₂NaErCl₆ was studied.The specific doping position of Li⁺was determined through the analysis of the material’s refined XRD patterns,XPS patterns,and upconversion luminescence spectra,Through kinetic analysis and theoretical simulation calculations,the lithium storage mechanism of the double perovskite material Cs₂NaErCl₆ was clarified,and the application direction of the halide double perovskite material in the field of anode electrode materials for lithium ion batteries was explored.（2）The layered double perovskite material Cs₄MnBi₂Cl₁₂ was prepared by physical grinding method as a negative electrode material for lithium ion batteries.Due to its unique layered structure,the effect of the layered structure on the electrochemical performance of the material was studied.The electrochemical impedance of the negative electrode of Cs₄MnBi₂Cl₁₂ was analyzed.It was found that the electrochemical impedance of the layered double perovskite material Cs₄MnBi₂Cl₁₂ was only half of that of the double perovskite material Cs₂NaErCl₆.Through in situ Raman testing and analysis of cyclic voltammetry curves,the lithium storage mechanism of layered double perovskite material Cs₄MnBi₂Cl₁₂ was revealed,providing ideas for improving the capacity and performance of double perovskite materials.