Preparation And Performance Researches Of Sulfide Solid Electrolytes In All-solid-state Lithium Batteries

All-solid-state lithium ion battery has the advantages of portability,non-toxic,high safety and so on,it has become the research hot spot of rechargeable lithium ion battery in recent years,rechargeable lithium ion battery,and was applied to electric vehicles,hybrid vehicles and high energy storage materials.The traditional lithium ion battery due to the existence of security risks of leakage,which is particularly prominent in the lithium ion battery with high power and high energy density.In order to solve this problem,the only way is to replace the traditional electrolyte with solid electrolyte.Because of the good safety,inorganic electrolyte especially sulfide electrolyte has become the research focus of solid electrolyte.Although,the sulfide electrolyte has several advantages such as:high lithium ion conductivity,good safety,high mechanical strength.There are also some deficiencies need to be improved.Compared with liquid electrolyte,the lithium ion conductivity of sulfide electrolyte have a large gap to cross.The cycle performance and charge-discharge performance of the all-solid-state lithium battery is poor.The sulfide electrolyte is unstable when exploring to the air.These problems are the barriers of the development and commercialization of the sulfide electrolyte.In this study,we introduce the development of the all-solid-state battery and sulfide solid electrolyte.We also classify the sulfide solid electrolyte,discuss the advantages and disadvantages.We use the vibration ball milling methods to prepare the Li₂S-P₂S₅,?100-x??0.7Li₂S–0.3P₂S₅?–xLi₂ZrO₃,?100-x??0.7Li₂S–0.3P₂S₅?–xWS₂solid electrolytes.The all-solid-state battery Li-In/SE/LiCoO₂ are assembled by the prepared electrolytes.X-ray diffraction,scanning electron microscopy,differential scanning calorimeter,Raman spectra,impedance spectroscopy are used to charaterizate materials'performances of the sulfide solid electrolytes.We used the cyclic voltammetry methods to test the performances of the all-solid-state batteries.The result of the study showed,at room temperature,the lithium ion conductivity of the two kind of ternary sulfide electrolyte are improved comparing with the lithium ion conductivity of the binary sulfide electrolyte.The lithium ion conductivity of Li₂S-P₂S₅,?100-x??0.7Li₂S–0.3P₂S₅?–xLi₂Zr O₃,?100-x??0.7Li₂S–0.3P₂S₅?–xWS₂ solid electrolyte we prepared are 1.65×10^-33 S cm^-1?2.85×10^-33 S cm^-1?1.97×10^-33 S cm^-1.The first discharge capacity of all-solid-state batteries assembled by the three electrolyte are 95.5mAhg^-1?113.0mAhg^-1?103.7m Ahg^-1.After 50 cycles,the discharge capacities are 77.8mAhg^-1?109.7mAhg^-1?94.3mAhg^-1.Rate of capacity retentions are 81.5%?97.1%?90.9%.Comparing with the all-solid-state batteries assembled by the binary sulfide electrolyte,the charge-discharge capacity and cycle performances of the all-solid-state batteries assembled by the ternary sulfide electrolyte are improved obviously.The above study results reveal that the methods of doping the third component into the binary electrolyte to improve the lithium ion conductivity of the sulfide electrolyte is feasible.This is also a way to improve the charge-discharge capacity and cycle performances of the all-solid-state batteries.