Novel Garnet-type Electrolyte Li7-xLa3Ce2-xTaxO12 with Fast Lithium Ion Conduction
Zipei Wan a, John Irvine a
a University of St Andrews, Physics and Astronomy, St Andrews, United Kingdom
nanoGe Fall Meeting
Proceedings of Materials for Sustainable Development Conference (MAT-SUS) (NFM22)
Solid State Batteries: Advances and challenges on materials, processing and characterization
Barcelona, Spain, 2022 October 24th - 28th
Organizers: Alex Morata, Albert Tarancón and Ainara Aguadero
Poster, Zipei Wan, 343
Publication date: 11th July 2022

Solid-state electrolytes are important for next-generation high-energy and safe lithium batteries. Compared to other type of solid electrolytes, oxide electrolytes present better thermal stability, higher electrochemical window and better air stability.[1] Among oxide electrolytes, garnet type A3B2(XO4)3 are especially promising to achieve high lithium-ion conductivity for high power lithium batteries. However, the currently synthesized garnet-type electrolytes are confined to Li7La3Zr2O12 (LLZO) and their doped derivatives. To obtain high Li-ion conductivity, these electrolytes need to be sintered at high temperature for long time[2], or by means of special sintering methods like spark plasma sintering (SPS)[3], hot isostatic pressing (HIP)[4], microwave-assisted sintering [5], resulting in high energy consumption and difficulty in scaling up. To solve these problems, the synthesis of new garnet electrolytes is urgently needed.

 

Herein, we synthesized a novel garnet electrolyte Li7-xLa3Ce2-xTaxO12 (LLCTO x, 0< x < 2) based on lanthanoid Ce4+ as main element and Ta5+ doped in B site. The Ta5+ substituting Ce4+ position helps Li7La3Ce2O12 (LLCO) to realize a phase transition from tetragonal to stable cubic at room temperature. On the other hand, Ce4+ occupying in Ta5+ site helps Li5La3Ta2O12 (LLTO) to increase cell parameter, leading to a huge enhancement of Li-ion conductivity. The bulk ceramic LLCTO 0.75 can achieve a high lithium-ion conductivity (0.87 mS cm-1 at 25 ℃ and 1.68 mS cm-1 at 40 ℃) by sintering at 1100~1125 ℃ for only 30 minutes.

 

[1] Wang C, Fu K, Kammampata S P, et al. Garnet-type solid-state electrolytes: materials, interfaces, and batteries[J]. Chemical reviews, 2020, 120(10): 4257-4300.

[2] Tong X, Thangadurai V, Wachsman E D. Highly conductive Li garnets by a multielement doping strategy[J]. Inorganic chemistry, 2015, 54(7): 3600-3607.

[3] Guillon O, Gonzalez‐Julian J, Dargatz B, et al. Field‐assisted sintering technology/spark plasma sintering: mechanisms, materials, and technology developments[J]. Advanced Engineering Materials, 2014, 16(7): 830-849.

[4] Qin S, Zhu X, Jiang Y, et al. Extremely dense microstructure and enhanced ionic conductivity in hot-isostatic pressing treated cubic garnet-type solid electrolyte of Ga2O3-doped Li7La3Zr2O12[J]. Functional Materials Letters, 2018, 11(02): 1850029.

[5] Mishra R R, Sharma A K. Microwave–material interaction phenomena: Heating mechanisms, challenges and opportunities in material processing[J]. Composites Part A: Applied Science and Manufacturing, 2016, 81: 78-97.

 

This work is supported by Professor John Irvine. The TEM test is operated by Dr David Miller and the Raman is tested by Dr Ioanna Pateli. The project is discussed by JTSI solid-state batteries group.

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