Visualization and evaluation of lithium diffusion at grain boundaries in Li0.29La0.57TiO3 solid electrolytes using secondary ion mass spectrometry

Gen Hasegawa; Naoaki Kuwata; Tsuyoshi Ohnishi; Kazunori Takada

doi:10.1039/d3ta05012b

Article Visualization and evaluation of lithium diffusion at grain boundaries in Li_0.29La_0.57TiO₃ solid electrolytes using secondary ion mass spectrometry

Gen Hasegawa (National Institute for Materials Science) ; Naoaki Kuwata (National Institute for Materials Science) ; Tsuyoshi Ohnishi (National Institute for Materials Science) ; Kazunori Takada (National Institute for Materials Science)

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Gen Hasegawa, Naoaki Kuwata, Tsuyoshi Ohnishi, Kazunori Takada. Visualization and evaluation of lithium diffusion at grain boundaries in Li_0.29La_0.57TiO₃ solid electrolytes using secondary ion mass spectrometry. Journal of Materials Chemistry A. 2023, (2), 731-738. https://doi.org/10.1039/d3ta05012b

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Understanding Li diffusion at the interfaces in solid-state Li batteries is essential to improving their performance (e.g., rate capabilities, energy densities). However, the visualization of Li diffusion at grain boundaries has been impossible due to the lack of experimental techniques. In this study, we visualize Li-ion diffusion at grain boundaries via secondary ion mass spectrometry at low temperatures (≈ −110 °C) using an isotope exchange technique for perovskite-type Li0.29La0.57TiO3 as a model solid electrolyte. The grain boundary diffusion coefficient obtained in this study is 1.4 × 10−13 cm2 s−1 at 25 °C, which is much smaller than the bulk diffusion coefficient of 2.6 × 10−8 cm2 s−1. The long-range effective diffusion coefficients can be explained well by a 1D model based on a series of bulk and grain boundaries. The Haven ratio of grain boundary diffusion suggests that correlation between the Li+ ions is crucial for grain boundary diffusion.

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