Enhancement of Low Temperature Superionic Conductivity by Suppression of Li Site Ordering in Li7Si2–xGexS7I


Han, Guopeng ORCID: 0000-0003-3861-5396, Daniels, Luke M ORCID: 0000-0002-7077-6125, Vasylenko, Andrij ORCID: 0000-0002-6933-0628, Morrison, Kate A, Corti, Lucia ORCID: 0000-0001-6493-8135, Collins, Chris M ORCID: 0000-0002-0101-4426, Niu, Hongjun, Chen, Ruiyong ORCID: 0000-0002-5340-248X, Roberston, Craig M, Blanc, Frédéric ORCID: 0000-0001-9171-1454 et al (show 3 more authors) (2024) Enhancement of Low Temperature Superionic Conductivity by Suppression of Li Site Ordering in Li7Si2–xGexS7I Angewandte Chemie, 136 (37). ISSN 0044-8249, 1521-3757

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Abstract

AbstractGe4+ substitution into the recently discovered superionic conductor Li7Si2S7I is demonstrated by synthesis of Li7Si2–xGexS7I, where x≤1.2. The anion packing and tetrahedral silicon location of Li7Si2S7I are retained upon substitution. Single crystal X‐ray diffraction shows that substitution of larger Ge4+ for Si4+ expands the unit cell volume and further increases Li+ site disorder, such that Li7Si0.88Ge1.12S7I has one Li+ site more (sixteen in total) than Li7Si2S7I. The ionic conductivity of Li7Si0.8Ge1.2S7I (x=1.2) at 303 K is 1.02(3)×10−2 S cm−1 with low activation energies for Li+ transport demonstrated over a wide temperature range by AC impedance and 7Li NMR spectroscopy. All sixteen Li+ sites remain occupied to temperatures as low as 30 K in Li7Si0.88Ge1.12S7I as a result of the structural expansion. This differs from Li7Si2S7I, where the partial Li+ site ordering observed below room temperature reduces the ionic conductivity. The suppression of Li+ site depopulation by Ge4+ substitution retains the high mobility to temperatures as low as 200 K, yielding low temperature performance comparable with state‐of‐the‐art Li+ ion conducting materials.

Item Type: Article
Uncontrolled Keywords: 3402 Inorganic Chemistry, 34 Chemical Sciences, 3406 Physical Chemistry, 40 Engineering, 4016 Materials Engineering
Depositing User: Symplectic Admin
Date Deposited: 11 Jul 2024 10:53
Last Modified: 06 Aug 2025 18:27
DOI: 10.1002/ange.202409372
Open Access URL: https://doi.org/10.1002/anie.202409372
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3182808
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