Speaker
Description
Solid-state batteries offer the promise of safer and higher energy density compared to contemporary Li-ion batteries, where the main hindrance to wide-scale commercial application is the lack of a suitable solid-state electrolyte material [1]. Li7La3Zr2O12 (LLZO) based materials show high promise as Li-ion conducting electrolytes for solid-state battery applications [2,3]. Despite the relatively high solid-state Li-ion conductivity, wide electrochemical stability window, and mechanical strength, the ionic conductivity of LLZO is still considerably lower than that of organic liquid-based electrolytes [3]. The partial substitution of Zr with Nb in LLZO has been shown to increase Li-ion conductivity through the formation of Li-vacancies and stabilization of the cubic phase [4,5]. To better understand the Nb-doping effect on the Li dynamics, a Nb-doped 7Li-isotope enriched LLZO, 7Li6.8La2.9Zr1.8Nb0.2O12 sample was investigated with polarized neutron scattering, performed on the LET spectrometer at ISIS, UK in the temperature range from 300 to 440 K. Neutron polarization analysis was used to separate the incoherent scattering dominantly caused by the dynamics of 7Li. The quasi-elastic incoherent scattering is fitted and analyzed to determine the presence of different 7Li-ion dynamics. The activation energy of the translational self-diffusion transport mode is determined and compared to other LLZO-based materials and with the values obtained by other methods. The mechanism for 7Li-ion jumps between the vacancies in the LLNZO crystal structure is analyzed and presented.
REFERENCES
[1] J. Janek, et al., Nat. Energy 8 (2023) 230–240.
[2] K.V. Kravchyk, et al., Sci. Rep. 12 (2022) 1177.
[3] C. Wang, et al., Chem. Rev. 120 (2020) 4257–4300.
[4] K. Miwa, et al., Phys. Rev. Mater. 2 (2018) 105404.
[5] H. Nozaki, et al., J. Phys. Soc. Jpn. 82 (2013) SA004.
