Low Temperature Synthesis And Performance Characterization Of Gernet-type Structure Solid Electrolyte Li₅La₃M₂O₁₂（M=Nb,Bi）

Lithium-ion battery is extensively applied in portable electronic devices due to the superior performances of high specific energy,high operating voltage,long cycle life,low self-discharge,no memory effect,meanwhile it has vast potential for future development in many other fields Traditional liquid organic electrolyte having a high ionic conductivity,but this kind of lithium-ion batteries are prone to leakage, the organic electrolyte and the electrode material contacts the thermal reaction,lead to the danger of fire or explosion. Researching and developing lithium ion electrolyte with a high electrochemical stability,high ion conductivity has an important significance for development of the lithium ion battery.Garnet structure of the lithium ion inorganic solid electrolyte Li5La3M2012overcomes the defects as low electrochemical stability,redox reaction occurs with electrode materials in LISICON, NASICON, perovskite solid electrolytes, garnet type lithium ion solid electrolyte Li5La3M2O12has a broad application prospects in the all-solid-state lithium-ion batteries,lithium-air battery. The garnet type lithium ion solid electrolyte Li5La3Nb2O12and Li5La3Bi2O12is studied in this paper, the influence of the preparation method and preparation conditions on the lithium ion conductivity in the material is also expored.Garnet structure Li5La3Nb2O12is prepared by sol-gel method in this paper, the samples prepared by sol-gel method need to be calcined at700℃for6h,which is250℃lower than the calcined temperature of conventional solid-phase synthesis method. The SEM analysis of the Li5La3Nb2O12samples calcined at900℃for6h shows good density,the ion conductivity of the samples prepared in this condition is calculated by the AC impedance analysis,the result is σLi (22℃)≈1.0×10-5S/cm. Li5La3Nb2O12with lithium ion battery used positive electrode material LiMn2O4and LiCoO2remains chemically stable at hign temperature environment. Li5La3Bi2O12ceramics were prepared by the sol-gel process, the scanning electron microscopy analysis of the Li5La3Bi2O12samples calcined at620℃for6h shows a good density,the lithium ion conductivity can be calculated by the AC impedance analysis, and result is σLi(22℃)≈2.0×10-4S/cm, which is higher than the samples prepared by solid-phase synthesis method. Moreover Li5La3Bi2O12with lithium ion battery used positive electrode LiMn2O4and LiCoO2remains chemically stable high temperature.