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Hanmei Tang1 Zhi Deng1 Zhuonan Lin1 Zhenbin Wang1 Iek-Heng Chu1 Chi Chen1 Zhuoying Zhu1 Chen Zheng1 Shyue Ping Ong1

1, University of California, San Diego, La Jolla, California, United States

The reactions occurring at interfaces have a profound impact on the performance of a rechargeable alkali-ion batteries. In this talk, we will present useful insights into materials selection strategies for enabling stable electrode/solid electrolyte interfaces in all-solid-state sodium-ion batteries using a hierarchy of first principles approximations. We will demonstrate how thermodynamic approximations based on assumptions of fast alkali diffusion and multi-species equilibrium can be used to effectively screen combinations of Na-ion electrodes, solid electrolytes and buffer oxides for electrochemical and chemical compatibility, as well as mechanical compatibility. We find that exchange reactions, especially between simple oxides and thiophosphate groups to form PO43–, are the main cause for large driving forces for cathode/solid electrolyte interfacial reactions. High reactivity with large volume changes are also predicted at the Na anode/solid electrolyte interface, while the Na2Ti3O7 anode is predicted to be much more stable against a broad range of solid electrolytes. We identify several promising binary oxides with similar or better chemical compatibility with most electrodes and solid electrolytes than the commonly used Al2O3. Finally, we show that ab initio molecular dynamics simulations of the NaCoO2/Na3PS4 interface model predict that the formation of SO42– -containing compounds and Na3P are kinetically favored over the formation of PO43– -containing compounds, in contrast to the predictions of the thermodynamic models.

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