Preparation And Properities Of Li₆PS₅X Sulfide Solid Electrolytes

Liquid organic electrolyte is flammable,easy to leak and poor in thermal stability.With the replacement of liquid electrolyte with solid electrolyte,all-solid-state lithium ion battery can effectively mitigate the potential safety hazard exist in traditional lithium ion battery.Additionally,all-solid-state lithium ion battery has the advantages of long cycle life and high energy density,and is expected to be applied to electric vehicles and smart grid and other large-scale energy storage fields.Solid electrolyte is an important component of all-solid-state battery.Thus the development of solid electrolyte with excellent performance is prerequisite to improve the performance of the all-solid-state battery.In addition,in all-solid-state batteries,the interface impedance between the electrolyte and electrode is large.Therefore,reducing the interface impedance is another effective method to improve the performance of all-solid-state lithium ion batteries.In this study,Li₆PS₅X?X=Cl?Br?I?solid electrolyte was prepared with Li₂S,P₂S₅and LiCl as the starting material.Also the structure and electrochemical properities of Li₆PS₅X?X=Cl?Br?I?have been characterized.The experimental results show that Li₆PS₅Cl prepared by solid state sintering with slightly higher content of Li₂S shows the highest ionic conductivity of 1.8×10^-3 S/cm at room temperature.Li₆PS₅Cl was coated on the electrode of MoS₂,and the all-solid-state battery assembled with the metioned MoS₂as cathode shows excellent cycling performance.In this study,O dopped Li₆PS_5-xO_xBr argyrodite sulfide electrolyte was also prepared by solid state sintering,and the O dopped position was characterized by experiment combined with theoretical calculation.The results show that S is much more easily replaced by O in the position of 4 a or 4 d for Li₆PS₅Br.The electrolyte of Li₆PS_4.7O_0.3Br with the x value of 0.3 has good chemical stabilty in air.At the same time,the electrolyte also has good electrochemical stability against lithium which can effectively prevent the growth of lithium dendrites.The all-solid-state battery assembled with Li₆PS_4.7O_0.3Br shows good cycling stability.In this study,Li₆PS₅Cl was prepared by liquid method,and its structure and electrochemical properities were characterized.The experimental results show that Li₆PS₅Cl obbtained by liquid method has a smaller particle size however with a certain amount of heterophase,resulting in a relatively low ionic conductivity at room temperature.Li₆PS₅Cl prepared by liquid method was uniformly coated on the surface of LiCoO₂ and the all-solid-state battery using the coated LiCoO₂ shows good cycling stability and excellent multiplying perfprmance.