湿化学法制备石榴石型固态电解质Li7La3Zr2O12

锂电池因能量密度高、循环寿命长、绿色清洁等特点被广泛应用，但其液态电解质易泄漏、挥发，且隔膜易被锂枝晶刺穿造成短路，引发危险。固态电解质大多是不具燃烧性的无机材料，室温下离子电导率较高、电化学窗口宽且适用温度范围广。因此，采用固态电解质替代液态电解质具有十分重要的意义。相对于其他类型固态电解质，石榴石型氧化物Li₇La₃Zr₂O₁₂（LLZO）具有离子电导率高、电化学窗口宽（>5V vs. Li/Li⁺）、对锂稳定性好和热稳定性高等特点，是非常具有发展潜力的无机固态电解质。本文采用溶胶-凝胶法和低温燃烧法两种湿化学法合成LLZO粉末，对应的电解质片在40℃时的离子电导率分别为1.22×10^-5S/cm和3.87×10^-6S/cm，活化能分别为0.34eV和0.32eV。从实验结果综合比较，溶胶-凝胶法为最佳制备方法。

Preparation Li7La3Zr2O12 garnet solid-state electrolyte by wet-chemical technique

Lithium-ion batteries are widely used as high energy density, long cycle life and green cleaning. However, lithium dendrite occurs easily in lithium-ion batteries with conditional leaky and volatile liquid electrolyte, which will cause short circuit and further danger. Solid-state electrolyte is nonflammable because most of them are inorganic material such as glass, ceramics and so on. Furthermore, solid-state has high ion conductivity at room temperature, wide electrochemical window, and extensive applicable temperature range. Therefore, it is very significant to replace traditional liquid electrolyte with solid-state electrolyte. Compared with other kinds of solid electrolytes, garnet oxide solid-state electrolyte Li₇La₃Zr₂O₁₂ (LLZO) with high ionic conductivity, wide electrochemical window (>5V vs. Li/Li⁺), stability to lithium metal and thermostabilization is a very promising inorganic solid electrolyte. Sol-gel method and low temperature combustion method were used to prepare LLZO powder in this work. The ionic conductivity at 40℃ and activation energy of the electrolyte pellets prepared by two methods were 1.22×10^-5 S/cm, 0.34eV and 3.87×10^-6 S/cm, 0.32eV, respectively. The result shows that sol-gel is more likely to be selected to prepare LLZO powder.