The Preparation And Characterization Of The Ni,（W）Doped Li₇la₃zr₂o₁₂electrolyte

All solid-state lithium-ion batteries have high safety due to the use of solid electrolytes instead of flammable organic liquid electrolytes,which will become the future development direction of lithium-ion batteries.The Li₇La₃Zr₂O₁₂ garnet-type inorganic solid electrolytes has become a research hotspot for lithium ion solid electrolytes due to its good electrochemical performance.In this paper,Ni-doped and Ni,W co-doped Li₇La₃Zr₂O₁₂ solid electrolytes were prepared by solid-state reaction.The effects of preparation processes on properties of the sample and the stability of the sample in air were studied.The samples were characterized by AC impedance,scanning electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy.The results are as follows:1)The solid electrolyte of Li_7-2xNi_xLa₃Zr₂O₁₂（0≤x≤0.45）,Li_7+2yLa₃Zr_2-yNi_yO₁₂（0.1≤y≤0.3）are prepared by solid-state reaction,when x=0.15 mol,the ionic conductivity of Li_6.7Ni_0.15La₃Zr₂O₁₂ is the highest.The calcination temperature of 900℃,lithium salt of Li₂CO₃ and excess 20 wt%,pressure of 30 MPa,sintering temperature of 1160℃,and buried powder of 3 g are preferred conditions for preparing the sample,and the conductivity of the sample under this condition is 3.10×10^-4 S·cm^-1（at room temperature）,the relative density is91.15%,the shrinkage is 6.76%,and the activation energy is 0.37 e V,X-ray diffraction shows that the sample prepared by the conditions is the cubic phase garnet structure of Ia-3d.2)The solid electrolyte of Li_6.7-2zNi_0.15La₃Zr_2-zW_zO₁₂（0.05≤z≤0.35）are prepared by solid-state reaction,when z=0.15 mol,the ionic conductivity of Li_6.4Ni_0.15La₃Zr_1.85W_0.15O₁₂ is the highest.The lithium salt of Li₂CO₃and excess 20 wt%,the nickel source of Ni CO₃·2Ni（OH）₂·4H₂O,the sintering temperature of 1160℃,the pressure of 30 MPa,and the buried powder of 4 g are preferred conditions for preparing the sample,and the conductivity of the sample under this condition is 3.86×10^-4S·cm^-1（at room temperature）,the relative density is 93.29%,the shrinkage is 7.60%,and the activation energy is 0.33 e V,X-ray diffraction shows that the sample prepared by the conditions is the cubic phase garnet structure of Ia-3d,The SEM result showed that the crystal grains of the sample are in close contact.3)After the sample Li_6.7Ni_0.15La₃Zr₂O₁₂ and Li_6.4Ni_0.15La₃Zr_1.85W_0.15O₁₂ has placed in the air for three months,the ionic conductivity decreased,and the XRD results show that Li₂CO₃was formed,which may be related to ion exchange with CO₂ and H₂O in the air.4)Innovations:The studies on Ni²⁺doped and Ni²⁺,W⁶⁺co-doped Li₇La₃Zr₂O₁₂ solid electrolytes have not been reported.