Electrolyte Properties of Li 4 P 2 S 6 -- Simulations and Comparison with Experiment

Structural and electrolyte properties of Li 4 P 2 S 6 have been investigated with computer simulations and with a variety of experiments including X-ray and neutron diffraction, electrochemical measurements, and thermal response. Compared with other thiophosphate materials, Li 4 P 2 S 6 is quite stable; maintaining the same crystal structure up to temperatures as high as 950 degrees C in vacuum and up to 280 degrees C in air. While its ionic conductivity is relatively small, its Arrhenius activation energy of 0.29 eV is similar to technologically viable electrolytes. Computer simulations provide insight into the causes and effects of disorder in this material and indicate that the mechanism of the ion conductivity is dominated by interstitial sites. Simulations of idealized interfaces of a Li 4 P 2 S 6 electrolyte with a Li metal anode are also analyzed. Acknowledgements: The computational portion of this work was supported by NSF grant DMR-1105485. Z. D. Hood was supported by the Higher Education Research Experiences (HERE) program at Oak Ridge National Laboratory. The experimental portion of this work was primarily conducted at the Center for Nanophase Materials Sciences and ORNL’s Spallation Neutron Source , which are DOE Office of Science User Facilities. Cameron Kates, Shiba Adhikari, and Chengdu Liang also contributed to this project. Assistance from Jong Keum, Andrew Payzant, Gayatri Sahu, Hui Wang, Keerthi Senevirathne, Cynthia Day, and Abdessadek Lachgar are also gratefully acknowledged.