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


Han, G ORCID: 0000-0003-3861-5396, Daniels, LM ORCID: 0000-0002-7077-6125, Vasylenko, A ORCID: 0000-0002-6933-0628, Morrison, KA, Corti, L ORCID: 0000-0001-6493-8135, Collins, CM ORCID: 0000-0002-0101-4426, Niu, H, Chen, R ORCID: 0000-0002-5340-248X, Roberston, CM, Blanc, F 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 International Edition, 63 (37). e202409372-. ISSN 1433-7851, 1521-3773

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Abstract

Ge4+ substitution into the recently discovered superionic conductor Li<inf>7</inf>Si<inf>2</inf>S<inf>7</inf>I is demonstrated by synthesis of Li<inf>7</inf>Si<inf>2–x</inf>Ge<inf>x</inf>S<inf>7</inf>I, where x≤1.2. The anion packing and tetrahedral silicon location of Li<inf>7</inf>Si<inf>2</inf>S<inf>7</inf>I 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 Li<inf>7</inf>Si<inf>0.88</inf>Ge<inf>1.12</inf>S<inf>7</inf>I has one Li+ site more (sixteen in total) than Li<inf>7</inf>Si<inf>2</inf>S<inf>7</inf>I. The ionic conductivity of Li<inf>7</inf>Si<inf>0.8</inf>Ge<inf>1.2</inf>S<inf>7</inf>I (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 Li<inf>7</inf>Si<inf>0.88</inf>Ge<inf>1.12</inf>S<inf>7</inf>I as a result of the structural expansion. This differs from Li<inf>7</inf>Si<inf>2</inf>S<inf>7</inf>I, 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
Additional Information: None.
Uncontrolled Keywords: 3402 Inorganic Chemistry, 34 Chemical Sciences
Depositing User: Symplectic Admin
Date Deposited: 04 Jul 2024 09:41
Last Modified: 24 Apr 2026 19:13
DOI: 10.1002/anie.202409372
Open Access URL: https://doi.org/10.1002/anie.202409372
Related Websites:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3182632
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