The design of advanced electrolytes hinges critically on a comprehensive comprehension of lithium-ion migration mechanisms within these electrochemical systems. Fluorination generally improves the stability and reduce...The design of advanced electrolytes hinges critically on a comprehensive comprehension of lithium-ion migration mechanisms within these electrochemical systems. Fluorination generally improves the stability and reduces the reactivity of organic compounds, making them potentially suitable for use in harsh conditions such as those found in a battery electrolyte. However,the specific properties, such as the solvation power, diffusivity, ion mobility, and so forth, would depend on the exact nature and extent of the fluorination. In this work, we introduce a theoretical framework designed to facilitate the autonomous creation of electrolyte molecular structures and craft methodologies to compute transport coefficients, providing a physical interpretation of fluoride systems. Taking fluorinated-1,2-diethoxyethanes as electrolyte solvents, we present and analyze the relationship between the electronic properties and atomic structures, and further correlate these properties to the transport coefficients, resulting in a good alignment with the experimental diffusion behaviors and Li-solvation structures. The insights derived from this research contribute to the methodological basis for high-throughput evaluation of prospective electrolyte systems, and consequently, propose strategic directions for the improvement of electrochemical cycle characteristics. This comprehensive exploration of the transport mechanisms enhances our understanding, offering avenues for further advancements in the field of lithium-ion battery technology.展开更多
This study investigates the formation process of Ni-Nb-Al metallic glasses. To this end, a long-range n-body potential was constructed for the Ni-Nb-Al ternary metal system, and applied to atomistic simulations. The s...This study investigates the formation process of Ni-Nb-Al metallic glasses. To this end, a long-range n-body potential was constructed for the Ni-Nb-Al ternary metal system, and applied to atomistic simulations. The simulations not only showed the physical origins of the amorphous phase formation, but also quantitatively predicted a hexagonal compositional region that energetically favors the glass formation. The energy difference between the solid solution and metallic glass, which generates the amorphization driving force(ADF), was suggested to indicate the glass-formation ability(GFA) of each alloy. Based on the computed ADFs, the Ni55 Nb25 Al20 alloy exhibited the highest GFA among the Ni-Nb-Al members, implying that the glass formed by this amorphous alloy is more thermodynamically stable than other alloys in the system. In a Voronoi tessellation analysis, the knee point of the coordination-number distribution curve corresponded to the glass-formation region of the Ni-NbAl system.展开更多
基金supported by the National Natural Science Foundation of China(Grant No. 52302302)the National Key R&D Program of China(Grant No. 2022YFE0208000)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Special Funds of the Tongji University for "Sino-German Cooperation 2.0 Strategy"。
文摘The design of advanced electrolytes hinges critically on a comprehensive comprehension of lithium-ion migration mechanisms within these electrochemical systems. Fluorination generally improves the stability and reduces the reactivity of organic compounds, making them potentially suitable for use in harsh conditions such as those found in a battery electrolyte. However,the specific properties, such as the solvation power, diffusivity, ion mobility, and so forth, would depend on the exact nature and extent of the fluorination. In this work, we introduce a theoretical framework designed to facilitate the autonomous creation of electrolyte molecular structures and craft methodologies to compute transport coefficients, providing a physical interpretation of fluoride systems. Taking fluorinated-1,2-diethoxyethanes as electrolyte solvents, we present and analyze the relationship between the electronic properties and atomic structures, and further correlate these properties to the transport coefficients, resulting in a good alignment with the experimental diffusion behaviors and Li-solvation structures. The insights derived from this research contribute to the methodological basis for high-throughput evaluation of prospective electrolyte systems, and consequently, propose strategic directions for the improvement of electrochemical cycle characteristics. This comprehensive exploration of the transport mechanisms enhances our understanding, offering avenues for further advancements in the field of lithium-ion battery technology.
基金supported by the Ministry of Science and Technology of China(Grant Nos.2017YFB0702301,2017YFB0702201&2017YFB0702401)the National Natural Science Foundation of China(Grant Nos.51571129,51631005)the Administration of Tsinghua University
文摘This study investigates the formation process of Ni-Nb-Al metallic glasses. To this end, a long-range n-body potential was constructed for the Ni-Nb-Al ternary metal system, and applied to atomistic simulations. The simulations not only showed the physical origins of the amorphous phase formation, but also quantitatively predicted a hexagonal compositional region that energetically favors the glass formation. The energy difference between the solid solution and metallic glass, which generates the amorphization driving force(ADF), was suggested to indicate the glass-formation ability(GFA) of each alloy. Based on the computed ADFs, the Ni55 Nb25 Al20 alloy exhibited the highest GFA among the Ni-Nb-Al members, implying that the glass formed by this amorphous alloy is more thermodynamically stable than other alloys in the system. In a Voronoi tessellation analysis, the knee point of the coordination-number distribution curve corresponded to the glass-formation region of the Ni-NbAl system.
