The Development Of Cu,Ba-Doped Li₇La₃Zr₂O₁₂ Solid Electrolyte

Organic liquid electrolyte has the possibility of leakage and combustion under certain conditions,which may cause a safety hazard.The replacement of organic liquid electrolytes with inorganic solid electrolytes is expected to improve battery safety.The garnet-type solid electrolyte has high lithium ion conductivity,good chemical properties and a wide voltage window.Among garnet-type electrolytes,Li₇La₃Zr₂O₁₂?LLZO?garnet-type electrolyte gets much attention,and its lithium ion conductivity can reach a higher level after proper doping.In this paper,Li_7.03-2XCu_xLa_2.97Ba_0.03Zr₂O₁₂?0?x?0.5?and Li_6.3+yCu_0.35La_3-yBa_yZr₂O₁₂?0?y?0.05?solid electrolyte are prepared by high-temperature solid-phase method,and Li_6.33Cu_0.35La_2.97Ba_0.03Zr₂O₁₂ solid electrolyte is assembled into a solid-state battery.The preparation process of solid electrolyte doped Cu content,Ba content,types of lithium salt,lithium salt content,calcination temperature and sintering temperature and their stability in air were studied.The prepared products are characterized by AC impedance,X-ray diffraction,scanning electron microscope,X-ray photoelectron and so on.The cyclic performance of the solid-state battery was analyzed using a constant current charge and discharge test.Main research results are as follows:1)Prepared Li_7.03-2xCu_xLa_2.97Ba_0.03Zr₂O_{120?x?0.5and Li6.3+yCu0.35La3-yBayZr2O12?0?y?0.05?solid electrolytes:x=0.35,y=0.03,Li2CO3 is a lithium salt with an excess of 10wt%,calcination temperature of 900?,and sintering temperature of 1160?.The room temperature ion conductivity of the solid electrolyte prepared under this condition is 1.96×10-3 S cm-1,the relative density is 96.2%,the shrinkage is 9.2%,and the activation energy is 0.31 eV.X-ray diffraction indicated that Li6.33Cu0.35La2.97Ba0.03Zr2O12 solid electrolyte has a cubic garnet structure.X-ray photoelectron spectroscopy results show that the doping state of Cu in the sample is+2.2}Li_6.33Cu_0.35La_2.97Ba_0.03Zr₂O₁₂ solid electrolyte is placed in the air,and the conductivity dropped to 1.17×10-4 S cm-1 after 3 months,and Li2CO3 was generated on the surface.3)Using Li_6.33Cu_0.35La_2.97Ba_0.03Zr₂O₁₂ as a solid electrolyte,it was assembled with graphite,lithium iron phosphate,lithium cobaltate,nickel cobalt manganese oxide and lithium metal sheets to form a button battery.Among them,LFP | LCLBZO | Li solid battery has a discharge voltage platform at about 3.37 V.The battery's first discharge specific capacity is 156.4 mAhg-1,the 20th cycle discharge specific capacity is 155.5 mA h g-1,and the capacity retention rate is 99.4%.The first Coulomb efficiency of the battery was 96.13%,and the Coulomb efficiency after the 20th cycle was 100.58%.NCM811 | LCLBZO | Li solid battery has a discharge voltage platform at about 3.7V.The battery's first discharge specific capacity is 189.3mAhg-1,the 20th cycle discharge specific capacity is 174 mA h g-1,and the capacity retention rate is 91.9%.The battery's first coulombic efficiency was 98.75%,and after 20 laps the coulombic efficiency was 100.46%.