Structure and ion transport of lithium-rich Li1+xAlxTi2−x(PO4)3 with 0.3<x<0.5: A combined computational and experimental study

• Published in: Solid state ionics 2020-03, Vol.346, p.1, Article 115192
• Main Authors: Case, David, McSloy, Adam J., Sharpe, Ryan, Yeandel, Stephen R., Bartlett, Thomas, Cookson, James, Dashjav, Enkhtsetseg, Tietz, Frank, Naveen Kumar, C.M., Goddard, Pooja
• Format: Article
• Language: English
• Subjects: Batteries; Computer simulation; Crystal structure; Electrolytes; Flammability; Garnets; Ion transport; Lithium; Molten salt electrolytes; Neutron diffraction; Robustness (mathematics); Solid electrolytes; Solid state physics; Transport properties
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2019.115192

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 0.3Al3+. Furthermore, our calculated ionic conductivities are in excellent agreement with experimental values, highlighting the robustness of our computational models. [Display omitted] •New solid state electrolytes are becoming increasingly sought after in the drive to replace flammable liquid electrolytes.•Li-rich materials have been of great interest with LLZO and LATP taking center stage.•Our Computational and experimental investigation show the structural sensitivities by comparing the site occupancies at varying temperature.•We investigate the Li ion transport properties using MD simulations which have not reported computationally before.•Our MD analyses confirms that the migration pathway only involves the M1(6b) and M2(18e) site, in excellent agreement with the neutron diffraction data.•We calculate low migration barriers (0.3eV) in line with experimental findings but also show evidence of Li ion trapping on Al doping.•This may explain why a no improved Li ion conductivity is observed experimentally above x=0.3.•Our calculated ionic conductivities are in excellent agreement with experiment