Li_0.33La_0.57TiO₃固体电解质固相合成及其掺杂改性

Solid-State Reaction Synthesis and Zr-Doped Optimization of Li_0.33La_0.57TiO₃ Solid Electrolyte

摘要: 在无机固体电解质中，氧化物基固体电解质因其具有稳定的机械性能和电化学性能，而很有希望应用于下一代锂电池当中，并且可以为锂电池中电解质泄露及产生火花等不安全问题提供一个有效的解决方案。Li_0.33La_0.57TiO₃作为电解质材料，拥有很高的晶粒电导率，但晶界电导率偏低。本文采用传统固相法成功制备出立方相Li_0.33La_0.57TiO₃，实验中通过调节烧结温度，发现在相同烧结时长下，1300℃得到的LLTO电解质的结晶度和纯度要比在1200℃、1250℃、1350℃下的高，且在此温度下取得电解质电导率的最大值2.29 × 10⁻⁵ S/cm，晶粒电导率则接近于1 × 10⁻³ S/cm。为了进一步提升材料的导电性，采用Zr⁴⁺掺杂，通过XRD和SEM分析，发现Zr⁴⁺掺杂量为6% mol时，经过12小时和24小时的保温烧结后，材料的晶界特性得到明显优化，致密性明显提升。通过交流阻抗测试，发现材料的总电导率分别达到4.99 × 10⁻⁵ S/cm和1.29 × 10^-4 S/cm。

Abstract: In terms of inorganic solid electrolytes, oxide-based materials are promising candidates for the next-generation lithiumion battery because of their high stability in mechanical, chemical and electrochemical aspects. Furthermore, lithium solid electrolytes can potentially address several key limitations of organic or liquid electrolytes used in today’s lithium batteries, namely, their fire exposure, leakage and limited electrochemical stability. As a typical solid state electrolyte material, Li_0.33La_0.57TiO₃ ceramic displays excellent ionic conductivities at room temperature, especially a high bulk lithiumion, but not grain boundary, conductivity of about 10⁻³ S/cm as reported in literature. Here, electrolyte ceramics of lithium lanthanum titanate [Li_0.33La_0.57TiO₃(LLTO)] and corresponding Zr⁴⁺-doped samples were prepared by conventional solid state reaction. Ceramics of LLTO sintered at different temperatures were comparatively investigated. It was observed that LLTO sintered at 1300˚C exhibited a higher total Li-ion conductivity of about 2.29 × 10⁻⁵ S/cm compared with those sintered at other temperatures. In order to enhance the Li-ion conductivity further, a synergistic optimization of zirconium doping and sintering time elongation has been performed. And the results show that the sample prepared under the optimal condition possesses a highest total ionic conductivity of 1.29 × 10^-4 S/cm through the AC impedance measurement. This is probably because the grain boundary in LLTO was effectively modified and the porosity between grains was reduced extremely.

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文章引用：胡志伟, 江跃, 朱小红. Li_0.33La_0.57TiO₃固体电解质固相合成及其掺杂改性[J]. 凝聚态物理学进展, 2018, 7(1): 12-21. https://doi.org/10.12677/CMP.2018.71003

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