Duff, Benjamin B, Corti, Lucia, Turner, Bethan, Han, Guopeng 
ORCID: 0000-0003-3861-5396, Daniels, Luke M ORCID: 0000-0002-7077-6125, Rosseinsky, Matthew J ORCID: 0000-0002-1910-2483 and Blanc, Frédéric ORCID: 0000-0001-9171-1454
(2024)
Revealing the Local Structure and Dynamics of the Solid Li Ion Conductor L3P5O14
Chemistry of Materials, 36 (16).
pp. 7703-7718.
ISSN 0897-4756, 1520-5002
Abstract
The development of fast Li ion-conducting materials for use as solid electrolytes that provide sufficient electrochemical stability against electrode materials is paramount for the future of all-solid-state batteries. Advances on these fast ionic materials are dependent on building structure-ionic mobility-function relationships. Here, we exploit a series of multinuclear and multidimensional nuclear magnetic resonance (NMR) approaches, including 6Li and 31P magic angle spinning (MAS), in conjunction with density functional theory (DFT) to provide a detailed understanding of the local structure of the ultraphosphate Li<inf>3</inf>P<inf>5</inf>O<inf>14</inf>, a promising candidate for an oxide-based Li ion conductor that has been shown to be a highly conductive, energetically favorable, and electrochemically stable potential solid electrolyte. We have reported a comprehensive assignment of the ultraphosphate layer and layered Li<inf>6</inf>O<inf>16</inf>26- chains through 31P and 6Li MAS NMR, respectively, in conjunction with DFT. The chemical shift anisotropy of the eight resonances with the lowest 31P chemical shift is significantly lower than that of the 12 remaining resonances, suggesting the phosphate bonding nature of these P sites being one that bridges to three other phosphate groups. We employed a number of complementary 6,7Li NMR techniques, including MAS variable-temperature line narrowing spectra, spin-alignment echo (SAE) NMR, and relaxometry, to quantify the lithium ion dynamics in Li<inf>3</inf>P<inf>5</inf>O<inf>14</inf>. Detailed analysis of the diffusion-induced spin-lattice relaxation data allowed for experimental verification of the three-dimensional Li diffusion previously proposed computationally. The 6Li NMR relaxation rates suggest sites Li1 and Li5 (the only five-coordinate Li site) are the most mobile and are adjacent to one another, both in the a-b plane (intralayer) and on the c-axis (interlayer). As shown in the 6Li-6Li exchange spectroscopy NMR spectra, sites Li1 and Li5 likely exchange with one another both between adjacent layered Li<inf>6</inf>O<inf>16</inf>26- chains and through the center of the P<inf>12</inf>O<inf>36</inf>12- rings forming the three-dimensional pathway. The understanding of the Li ion mobility pathways in high-performing solid electrolytes outlines a route for further development of such materials to improve their performance.
| Item Type: | Article |
|---|---|
| Additional Information: | No legal or ethical issues. Data will be uploaded shortly when preperation activities are complete. |
| Uncontrolled Keywords: | 40 Engineering, 4016 Materials Engineering, 34 Chemical Sciences, 3406 Physical Chemistry |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 30 Jul 2024 10:31 |
| Last Modified: | 24 Apr 2026 19:14 |
| DOI: | 10.1021/acs.chemmater.4c00727 |
| Open Access URL: | https://pubs.acs.org/doi/10.1021/acs.chemmater.4c0... |
| Related Websites: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3183237 |
| 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. |
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