ID: 1712.06962

Analysis of diffusion in solid state electrolytes through MD-simulations, improvement of the Li-ion conductivity in \beta-Li3PS4 as an example

December 19, 2017

View on ArXiv
Klerk Niek J. J. de, der Maas Eveline van, Marnix Wagemaker
Physics
Condensed Matter
Chemical Physics
Materials Science

Molecular dynamics simulations are a powerful tool to study diffusion processes in battery electrolyte and electrode materials. From a single molecular dynamics simulation many properties relevant to diffusion can be obtained, including the diffusion path, attempt frequency, activation energies, and collective diffusion processes. These detailed diffusion properties provide a thorough understanding of diffusion in solid electrolytes, and provides direction for the design of improved solid electrolyte materials. Here a thorough analysis methodology is developed, and applied to DFT MD simulations of Li-ion diffusion in \beta-Li3PS4. The methodology presented is generally applicable to crystalline materials and facilitates the analysis of molecular dynamics simulations. The code used for the analysis is freely available at: https://bitbucket.org/niekdeklerk/md-analysis-with-matlab. The results on \beta-Li3PS4 demonstrate that jumps between bc-planes limit the conductivity of this important class of solid electrolyte materials. The simulations indicate that by adding Li-interstitials or Li-vacancies the rate limiting jump process can be accelerated significantly, which induces three dimensional diffusion, resulting in an increased Li-ion diffusivity. Li-vacancies can be introduced through Br-doping, which is predicted to result in an order of magnitude larger Li-ion conductivity in \beta-Li3PS4. Furthermore, the present simulations rationalise the improved Li-ion diffusivity upon O-doping through the creation of local Li-interstitials.

Similar papers 1