Yizhou Zhu1 Xingfeng He1 Yifei Mo1

1, University of Maryland-College Park, College Park, Maryland, United States

All-solid-state Li-ion battery based on solid electrolyte materials is a promising next-generation energy storage technology, providing intrinsic safety and higher energy density. Currently, high interfacial resistance and interfacial degradation at the solid electrolyte-electrode interfaces is the key bottleneck, limiting cycling and rate performance. Fundamental understanding about the interfaces is essential, yet lacking, due to the difficulty of directly access in experiments and the complicated microstructure to construct in modeling.

In this presentation, I will show how we use first principles computation to bring new understanding about these buried interfaces. Using our developed computation approach based on large materials database, we calculated the true electrochemical stability window of solid electrolytes and predicted interphase decomposition products, which are verified by in-situ experiments. I will discuss the critical role of decomposition interphase layers and their effects on the battery performance. From these insights, we are able to classify different interface types for different solid-electrolyte and electrode pairs and estimate their impacts on battery performance. Moreover, specific interfacial engineering strategies are proposed to address potential interface issues.

In addition, I will present the predicted chemistry trend and novel strategies to enable Li metal anode. Previous research efforts to stabilize Li metal anode was greatly impeded by the lack of knowledge about Li-stable materials chemistry. With first-principles calculations based on large materials database, we found that most oxides, sulfides, and halides, which were commonly studied as protection materials, are reduced by Li metal due to the reduction of metal cations. On the contrary, nitride anion chemistry exhibits unique stability against Li metal, which is either thermodynamically intrinsic or a result of stable passivation. Many nitrides materials may be promising candidates for Li metal anode protection to achieve long-term stability. This series of computational study provides novel insights and general guidance for material design and interfacial engineering in all-solid-state Li-ion batteries.

[1] Y. Zhu, X. He, Y. Mo, Origin of Outstanding Stability in the Lithium Solid Electrolyte Materials: Insights from Thermodynamic Analyses Based on First Principles Calculations. ACS Appl. Mater. Interfaces, 7, 23685-23693 (2015);

[2] Y. Zhu, X. He, Y. Mo, First principles study on electrochemical and chemical stability of solid electrolyte-electrode interfaces in all-solid-state Li-ion batteries. Journal of Materials Chemistry A, 4, 3253-3266 (2016)

[3] F. Han§, Y. Zhu§, X. He, Y. Mo, C. Wang, Electrochemical Stability of Li10GeP2S12 and Li7La3Zr2O12Solid Electrolytes. Adv. Energy Mater., 6, 1501590 (2016) (§ co-first author)

[4] Y. Zhu, X. He, Y. Mo, Strategies Based on Nitride Materials Chemistry to Stabilize Li Metal Anode. Adv. Sci., 1600517 (2017)