2134/11655825.v1
David Case
David
Case
Adam McSloy
Adam
McSloy
Ryan Sharpe
Ryan
Sharpe
Stephen Yeandel
Stephen
Yeandel
T Bartlett
T
Bartlett
J Cookson
J
Cookson
E Dashjav
E
Dashjav
F Tietz
F
Tietz
CM Naveen Kumar
CM Naveen
Kumar
Pooja Goddard
Pooja
Goddard
Structure and ion transport of lithium-rich Li1+xAlxTi2−x(PO4)3 with 0.3
Loughborough University
2020
Energy
Physical Chemistry (incl. Structural)
Materials Engineering
Condensed Matter Physics
2020-01-24 09:21:54
Journal contribution
https://repository.lboro.ac.uk/articles/journal_contribution/Structure_and_ion_transport_of_lithium-rich_Li1_xAlxTi2_x_PO4_3_with_0_3/11655825
© 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.