锂盐及制备工艺对固态电解质Li_(7)La_(3)Zr_(2)O_(12)成相的影响研究

Study on the effect of lithium salt and its preparation process on the phase formation of solid electrolyte Li_(7)La_(3)Zr_(2)O_(12)

石榴石型Li_(7)La_(3)Zr_(2)O_(12)(LLZO)离子导电性高,在全固态锂离子电池中具有潜在的应用价值。但目前报道的LLZO制备工艺烧结温度范围宽,稳定性差,不利于宏量制备。本文以烧结产物物相结构和结晶度为考察指标,系统研究了锂源及用量、烧结温度、烧结时间等因素对LLZO成相的影响。结果表明,当以分解温度较低的锂盐(LiNO_(3))为原料时,在800℃下得到四方相LLZO,900℃时呈立方相LLZO;当以分解温度较高的锂盐(Li_(2)CO_(3))为原料时,900℃才能形成四方相LLZO。烧结时间的延长和温度升高均会导致锂的挥发损失,影响LLZO物相的形成。通过增加锂盐用量、改变烧结前驱体聚集特性与烧结时间可抑制锂的挥发。当以过量10%的Li_(2)CO_(3)为原料时,900℃烧结6h可稳定的得到立方相LLZO。该研究较为系统地分析了制备工艺对LLZO成相的影响,可为LLZO宏量稳定制备提供借鉴。

Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO)has potential application value in all-solid lithium-ion batteries because of its high ion conductivity.However,the currently reported LLZO preparation process is not conducive to large-scale preparation due to the wide sintering temperature range and poor stability.Based on the physical phase structure and crystallinity of the sintered product,this paper systematically studied the influence of factors such as lithium source and dosage,sintering temperature and sintering time on LLZO phase formation.The results show that when lithium salt(Li_(2)CO_(3))with low decomposition temperature was used as raw material,LLZO of Tetragonal phase was obtained at 800℃,and LLZO of cubic phase was obtained at 900℃.When lithium salt(Li_(2)CO_(3))with higher decomposition temperature was used as raw material,LLZO of Tetragonal phase can be formed at 900℃.Prolonged sintering time and temperature increase lead to the loss of lithium volatilization,which affects the formation of LLZO phase.The volatilization of lithium can be inhibited by increasing the amount of lithium salt,changing the aggregation characteristics and sintering time of the sintering precursor.LLZO with cubic phase can be obtained stably with 10%excess Li_(2)CO_(3) as raw material after sintering at 900℃for 6h.This study systematically analyzes the influence of the preparation process on the phase of LLZO,which can provide a reference for the large-scale stable preparation of LLZO.