Shoko, E, Dang, Y 
ORCID: 0000-0002-0140-0140, Han, G ORCID: 0000-0003-3861-5396, Duff, BB ORCID: 0000-0002-7398-5002, Dyer, MS ORCID: 0000-0002-4923-3003, Daniels, LM ORCID: 0000-0002-7077-6125, Chen, R ORCID: 0000-0002-5340-248X, Blanc, F ORCID: 0000-0001-9171-1454, Claridge, JB ORCID: 0000-0003-4849-6714 and Rosseinsky, MJ ORCID: 0000-0002-1910-2483
(2021)
Polymorph of LiAlP2O7: Combined Computational, Synthetic, Crystallographic, and Ionic Conductivity Study
Inorganic Chemistry, 60 (18).
pp. 14083-14095.
ISSN 0020-1669, 1520-510X
|
Text
acs.inorgchem.1c01396.pdf - Published version Download (5MB) | Preview |
Abstract
We report a new polymorph of lithium aluminum pyrophosphate, LiAlP2O7, discovered through a computationally guided synthetic exploration of the Li-Mg-Al-P-O phase field. The new polymorph formed at 973 K, and the crystal structure, solved by single-crystal X-ray diffraction, adopts the orthorhombic space group Cmcm with a = 5.1140(9) Å, b = 8.2042(13) Å, c = 11.565(3) Å, and V = 485.22(17) Å3. It has a three-dimensional framework structure that is different from that found in other LiMIIIP2O7 materials. It transforms to the known monoclinic form (space group P21) above ∼1023 K. Density functional theory (DFT) calculations show that the new polymorph is the most stable low-temperature structure for this composition among the seven known structure types in the AIMIIIP2O7 (A = alkali metal) families. Although the bulk Li-ion conductivity is low, as determined from alternating-current impedance spectroscopy and variable-temperature static 7Li NMR spectra, a detailed analysis of the topologies of all seven structure types through bond-valence-sum mapping suggests a potential avenue for enhancing the conductivity. The new polymorph exhibits long (>4 Å) Li-Li distances, no Li vacancies, and an absence of Li pathways in the c direction, features that could contribute to the observed low Li-ion conductivity. In contrast, we found favorable Li-site topologies that could support long-range Li migration for two structure types with modest DFT total energies relative to the new polymorph. These promising structure types could possibly be accessed from innovative doping of the new polymorph.
| Item Type: | Article |
|---|---|
| Additional Information: | No access restrictions, data can be made immediately available. |
| Uncontrolled Keywords: | 3402 Inorganic Chemistry, 34 Chemical Sciences |
| Divisions: | Faculty of Science & Engineering > School of Physical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 13 Sep 2021 09:09 |
| Last Modified: | 01 Mar 2026 10:56 |
| DOI: | 10.1021/acs.inorgchem.1c01396 |
| Related Websites: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3136936 |
| Disclaimer: | The University of Liverpool is not responsible for content contained on other websites from links within repository metadata. Please contact us if you notice anything that appears incorrect or inappropriate. |
Altmetric
Altmetric