TY  - JOUR
AU  - Case, David
AU  - McSloy, Adam J.
AU  - Sharpe, Ryan
AU  - Yeandel, Stephen R.
AU  - Bartlett, Thomas
AU  - Cookson, James
AU  - Dashjav, Enkhtsetseg
AU  - Tietz, Frank
AU  - Naveen Kumar, C. M.
AU  - Goddard, Pooja
TI  - Structure and ion transport of lithium-rich Li1+Al Ti2−(PO4)3 with 0.3<x<0.5: A combined computational and experimental study
JO  - Solid state ionics
VL  - 346
SN  - 0167-2738
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2020-02630
SP  - 115192
PY  - 2020
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000517851600016
DO  - DOI:10.1016/j.ssi.2019.115192
UR  - https://juser.fz-juelich.de/record/878099
ER  -