Dual Substitution and Spark Plasma Sintering to Improve Ionic Conductivity of Garnet Li7La3Zr2O12

Zhencai Dong; Chao Xu; Yongmin Wu; Weiping Tang; Shufeng Song; Jianyao Yao; Zhengyong Huang; Zhaoyin Wen; Li Lu; Ning Hu

doi:10.3390/nano9050721

Dual Substitution and Spark Plasma Sintering to Improve Ionic Conductivity of Garnet Li₇La₃Zr₂O₁₂

Nanomaterials (Basel). 2019 May 10;9(5):721. doi: 10.3390/nano9050721.

Authors

Zhencai Dong¹, Chao Xu², Yongmin Wu³, Weiping Tang⁴, Shufeng Song⁵, Jianyao Yao⁶, Zhengyong Huang⁷, Zhaoyin Wen⁸, Li Lu^{9

10}, Ning Hu^{11

12

13}

Affiliations

¹ College of Aerospace Engineering, Chongqing University, Chongqing 400044, China. 20163113037@cqu.edu.cn.
² College of Electrical Engineering, Chongqing University, Chongqing 400044, China. xuchao1995@cqu.edu.cn.
³ State Key Laboratory of Space Power-sources Technology, Shanghai Institute of Space Power-Sources, Shanghai 200245, China. wuym2014@126.com.
⁴ State Key Laboratory of Space Power-sources Technology, Shanghai Institute of Space Power-Sources, Shanghai 200245, China. tangwp@sina.cn.
⁵ College of Aerospace Engineering, Chongqing University, Chongqing 400044, China. sfsong@cqu.edu.cn.
⁶ College of Aerospace Engineering, Chongqing University, Chongqing 400044, China. yaojianyao@cqu.edu.cn.
⁷ College of Electrical Engineering, Chongqing University, Chongqing 400044, China. huangzhengyong@cqu.edu.cn.
⁸ CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China. zywen@mail.sic.ac.cn.
⁹ Department of Mechanical Engineering, National University of Singapore, Singapore 117575, Singapore. luli@nus.edu.sg.
¹⁰ National University of Singapore Suzhou Research Institute, Suzhou 215024, China. luli@nus.edu.sg.
¹¹ College of Aerospace Engineering, Chongqing University, Chongqing 400044, China. ninghu@cqu.edu.cn.
¹² School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China. ninghu@cqu.edu.cn.
¹³ State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China. ninghu@cqu.edu.cn.

Abstract

Garnet Li₇La₃Zr₂O₁₂ is one of the most promising solid electrolytes used for solid-state lithium batteries. However, low ionic conductivity impedes its application. Herein, we report Ta-doping garnets with compositions of Li_7-xLa₃Zr_2-xTa_xO₁₂ (0.1 ≤ x ≤ 0.75) obtained by solid-state reaction and free sintering, which was facilitated by graphene oxide (GO). Furthermore, to optimize Li_6.6La₃Zr_1.6Ta_0.4O₁₂, Mg²⁺ was select as a second dopant. The dual substitution of Ta⁵⁺ for Zr⁴⁺ and Mg²⁺ for Li⁺ with a composition of Li_6.5Mg_0.05La₃Zr_1.6Ta_0.4O₁₂ showed an enhanced total ionic conductivity of 6.1 × 10^-4 S cm^-1 at room temperature. Additionally, spark plasma sintering (SPS) was applied to further densify the garnets and enhance their ionic conductivities. Both SPS specimens present higher conductivities than those produced by the conventional free sintering. At room temperature, the highest ionic conductivity of Li_6.5Mg_0.05La₃Zr_1.6Ta_0.4O₁₂ sintered at 1000 °C is 8.8 × 10^-4 S cm^-1, and that of Li_6.6La₃Zr_1.6Ta_0.4O₁₂ sintered at 1050 °C is 1.18 × 10^-3 S cm^-1.

Keywords: conductivity; dual substitution; garnet; spark plasma sintering.

Grants and funding

51702030/National Natural Science Foundation of China