Computational Identification and Experimental Realization of Lithium Vacancy Introduction into the Olivine LiMgPO₄

Enciso-Maldonado, Leopoldo, Dyer, Matthew S ORCID: 0000-0002-4923-3003, Jones, Michael D, Li, Ming, Payne, Julia L, Pitcher, Michael J ORCID: 0000-0003-2044-6774, Omir, Mona K, Claridge, John B ORCID: 0000-0003-4849-6714, Blanc, Frederic ORCID: 0000-0001-9171-1454 and Rosseinsky, Matthew J ORCID: 0000-0002-1910-2483 (2015) Computational Identification and Experimental Realization of Lithium Vacancy Introduction into the Olivine LiMgPO₄. CHEMISTRY OF MATERIALS, 27 (6). pp. 2074-2091.

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Abstract

Calculation of the energetics of aliovalent substitution into the olivine LiMgPO4 suggests that replacement of Mg2+ by In3+ is the most effective way to introduce lithium vacancies and thus generate Li ion conductivity. Experimental synthesis accesses materials with up to 17% Li vacancy content. An order-of-magnitude increase in the high-temperature hopping rates probed by 7Li NMR spin-lattice relaxation, and over 2 orders of magnitude increase in the room-temperature Li+ ion conductivity measured by impedance spectroscopy is observed upon the introduction of In3+ ions and Li vacancies. NMR spectroscopy and calculations reveal that the energy barrier to site-to-site hopping is 0.3-0.5 eV, comparable with best-in-class nonoxide systems such as argyrodite, but NMR-derived hopping rates, and impedance spectroscopy shows that longer range transport is less facile with activation energies in the range of 0.7-1 eV. Calculations suggest that this is because the Li vacancies are strongly bound to the In3+ dopants, suggesting that high lithium mobilities in oxides are accessible but high conductivities require strategies to separate defect from dopant.

Item Type:	Article
Subjects:	?? QD ??
Depositing User:	Symplectic Admin
Date Deposited:	02 Mar 2015 11:30
Last Modified:	17 Oct 2023 01:58
DOI:	10.1021/cm504518q
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/2007506