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Structure and ion transport of lithium-rich Li1+xAlxTi2−x(PO4)3 with 0.3

journal contribution
posted on 24.01.2020 by David Case, Adam McSloy, Ryan Sharpe, Stephen Yeandel, T Bartlett, J Cookson, E Dashjav, F Tietz, CM Naveen Kumar, Pooja Goddard
© 2020 Elsevier B.V. New solid state electrolytes are becoming increasingly sought after in the drive to replace flammable liquid electrolytes. To this end, several Li conducting solids have been identified as promising candidates including Li stuffed garnets and more recently Li-rich materials such as Li1+xAlxTi2−x(PO4)3 with 0.3< x <0.5. However, the structure/property relationships of LATP are incredibly sensitive to synthesis conditions and therefore challenging to optimise. In this joint computational and experimental investigation, we examine the structural sensitivities by modelling the site occupancies at varying temperature, which clarifies previously reported discrepancies of the crystal structures. Furthermore, we investigate the Li ion transport properties which have not reported computationally before. We confirm from our simulations that the migration pathway only involves the M1(6b) and M2(18e) site, in excellent agreement with the neutron diffraction data, clarifying all past controversies regarding the Li ion occupancies in LATP. Interestingly, we calculate low migration barriers (0.3 eV) in line with experimental findings but also show evidence of Li ion trapping on Al doping in LATP (where x = 0.4), possibly explaining the experimental observation that the Li ion conductivity does not improve above x = 0.3, due to a stronger repulsion between Li+–>Ti4+ compared to Li+–>Al3+. Furthermore, our calculated ionic conductivities are in excellent agreement with experimental values, highlighting the robustness of our computational models.

Funding

(EPSRC) Design and high throughput microwave synthesis of Li-ion battery materials : EP/N001982/1

History

School

  • Science

Department

  • Chemistry

Published in

Solid State Ionics

Volume

346

Publisher

Elsevier

Version

AM (Accepted Manuscript)

Rights holder

© Elsevier

Publisher statement

This paper was accepted for publication in the journal Solid State Ionics and the definitive published version is available at https://doi.org/10.1016/j.ssi.2019.115192

Acceptance date

12/12/2019

Publication date

2020-01-10

Copyright date

2020

ISSN

0167-2738

Language

en

Depositor

Dr Pooja Goddard Deposit date: 19 January 2020

Article number

115192

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