本发明公开了一种复合固态电解质及其制 备方法和应用，复合固态电解质的原料包括钽掺 杂立方相石榴石型固态电解质和复合助烧剂；按 重量份数计，LLZTO的重量份数≥80份且＜100 份，复合助烧剂的重量份数＞0份且≤20份； LLZTO的化学通式为Li7‑x La3 Zr2‑x Tax O12，0 .1≤x ≤0 .6；复合助烧剂为LiOH、Li2 B4 O7、Al2 O3、Ga2 O3 和SiO2中的至少两种。本发明引入的特定复合助 烧剂能够烧结形成非晶态物质并填充于晶粒间 的缝隙中，同时能够诱导晶粒尺寸两极分化，使 大量小尺寸晶粒填充于大尺寸晶粒之间，使复合 固态电解质具有低晶界电阻和高离子电导率。

The present invention discloses a composite solid state electrolyte and its preparation method and application, the raw materials of the composite solid state electrolyte include tantalum-doped cubic phase garnet solid state electrolyte and composite burnup agent; the weight of LLZTO is ≥80 parts by weight and <100 parts by weight, and the weight of the composite burnup agent is >0 parts by weight and ≤20 parts by weight; the chemical formula of LLZTO is Li7 -x La3 Zr2-x Tax O12, 0 . -x La3 Zr2-x Tax O12, 0 . 1 ≤ x ≤ 0 . 6; the composite combustion aid is at least two of LiOH, Li2 B4 O7, Al2 O3, Ga2 O3 and SiO2. The specific compound firing aid introduced in the present invention can sinter amorphous substances and fill the gaps between grains, and at the same time can induce polarization of grain size, so that a large number of small-size grains are filled between large-size grains, so that the composite solid state electrolyte has a low grain boundary resistance and high ionic conductivity.