Modification And Properties Of Lithium-rich Anti-perovskite Electrolytes

With the development of science and technology,people have higher and higher requirements for energy storage and use.The development of energy materials is more and more important by the state.Among various energy storage schemes,lithium-ion batteries are widely used in various fields because of their small volume,high energy density and light mass.However,because the traditional lithium-ion batteries mainly use organic solvents and solutes as electrolytes,the high temperature resistance of such electrolytes is poor,which can easily cause the safety problems such as combustion and explosion.As a traditional alternative to liquid electrolyte,solid electrolyte can avoid these hidden dangers because of its wide electrochemical window and non inflammable,which has become the focus of domestic and international research.Recently,a lithium rich perovskite electrolyte(Li RAP)Li₂OHCl has been found,and some reports have shown that it has a good electrochemical performance.In this paper,Li₂OHCl was prepared by molten salt method,and modified by doping alkaline earth metal ions and halogen ions,and the structure and electrochemical properties of the materials were studied.The main work of this paper includes the following parts:(1)The preparation of the perovskite electrolyte Li₂OHCl was carried out by molten salt method.The synthesis of the sample was further verified by XRD,SEM and TG.The results show that the electrolyte has good stability for lithium metal and good electrochemical stability.The synthesized samples have a wide electrochemical window(up to 10 V)and the conductivity can reach 1.10×10^-5 S/cm at 140?.The results show that the electrolyte can adapt to high voltage environment and work at high temperature.(2)Based on the previous work,the chlorine ions in the original molecular structure were replaced by adding trace F^-,Br^-,I^-respectively.The Li₂OHCl_0.99X_0.01 was synthesized by molten salt method.X=F,Br,I were obtained,and the synthesized samples were characterized by their properties and structures.Firstly,the synthesis of the samples was verified by XRD,SEM and TG.The results of the electrochemical performance test show that the electrochemical window of the synthesized sample is 10 V wide,and the lithium metal is still stable.The conductivity of the sample can reach 1.09×10^-4 S/cm at 140?The activation energy of the sample was 0.62 eV,which decreased compared with the undoped sample(0.82eV).The above experiments show that the doping method can improve the electrochemical performance of the electrolyte.(3)The electrolyte was mixed with Mg²⁺,Ca²⁺,Sr²⁺,Ba²⁺to replace some lithium ions in the original molecular structure.The synthesis was carried out by molten salt method. Y_0.01Li_1.98OHCl was obtained,where Y=Mg,Ca,Sr,Ba.Firstly,XRD,SEM and TG tests were carried out to verify the synthesis of the samples,which further indicated that the doping would not change the structure of the samples.The results show that the sample is stable and stable for lithium electrode.The electrochemical window is 10 V wide and the conductivity can reach 8.79×10^-5 S/cm at 140?.The activation energy of the sample is 0.60 eV,which proves that the activation energy of the sample can be reduced by this method.(4)Further doping is carried out in combination with previous work.In the halogen ions F^-,Br^-,I^-and alkaline earth metal ions Mg²⁺,Ca²⁺,Sr²⁺,Ba²⁺,respectively,one of the chloride ions and lithium ions in the electrolyte structure was selected to replace them.The samples were synthesized by molten salt method.Finally,Y_0.01Li_1.98OHCl_0.99X_0.01 was synthesized, where Y=Mg,Ca,Sr,Ba;X=F,Br,I.The performance and structure of the system were also characterized.XRD,SEM and TG test show that the doping method does not change the structure of the sample.The results of electrochemical performance test show that the synthesized sample is stable,the electrochemical window is up to 10 V,and the stability of lithium electrode is 4.92×10^-5 S/cm at 140?.The results show that the activation energy of the sample is 0.60eV at least.Compared with the samples without doping,the activation energy of the samples is decreased.It is proved that the electrochemical performance of the samples is improved by this method.