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

Han, Guopeng, Daniels, Luke ORCID: https://orcid.org/0000-0002-7077-6125, Vasylenko, Andrij, Morrison, Kate A., Corti, Lucia, Collins, Chris ORCID: https://orcid.org/0000-0002-0101-4426, Niu, Hongjun, Chen, Ruiyong, Robertson, Craig, Blanc, Frederic, Dyer, Matthew, Claridge, John and Rosseinsky, Matthew (2024) Enhancement of Low Temperature Superionic Conductivity by Suppression of Li Site Ordering in Li7Si2–xGexS7I. [Data Collection]

Data Catalogue DOI: 10.17638/datacat.liverpool.ac.uk/2649

Original publication URL: https://onlinelibrary.wiley.com/doi/full/10.1002/a...

Description

Ge4+ 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.

Keywords:

Solid electrolytes, ion conductors, Li ion battery, multiple anion chemistry, crystallography

Divisions:

Faculty of Science and Engineering > School of Physical Sciences > Chemistry

Depositing User:

Luke Daniels

Date Deposited:

11 Dec 2024 15:30

Last Modified:

11 Dec 2024 15:30

DOI:

10.17638/datacat.liverpool.ac.uk/2649