Fluorine-free electrolytes have attracted great attention because of its low-cost and environmental friendliness. However, so far, little is known about the solution structures of these electrolytes. Here,we compare t...Fluorine-free electrolytes have attracted great attention because of its low-cost and environmental friendliness. However, so far, little is known about the solution structures of these electrolytes. Here,we compare the solvation phenomenon of sodium tetraphenylborate(NaBPh_(4)) salt dissolved in organic solvents of propylene carbonate(PC), 1,2-dimethoxyethane(DME), acetonitrile(ACN) and tetrahydrofuran(THF). Small-angle X-ray scattering(SAXS) reveals a unique two-peak structural feature in this saltconcentrated PC electrolyte, while solutions using other solvents only have one scattering peak.Molecular dynamics(MD) simulations further reveal that there are anion-based clusters in addition to the short-range charge ordering in the concentrated NaBPh4/PC electrolyte. Raman spectroscopy confirms the existence of considerable contact ion pairs(CIPs). This work emphasizes the importance of global and local structural analysis, which will provide valuable clues for understanding the structureperformance relationship of electrolytes.展开更多
Conventional metasurfaces have demonstrated efficient wavefront manipulation by using thick and high-aspect-ratio nanostructures in order to eliminate interactions between adjacent phase-shifter elements.Thinner-than-...Conventional metasurfaces have demonstrated efficient wavefront manipulation by using thick and high-aspect-ratio nanostructures in order to eliminate interactions between adjacent phase-shifter elements.Thinner-than-wavelength dielectric metasurfaces are highly desirable because they can facilitate fabrication and integration with both electronics and mechanically tunable platforms.Unfortunately,because their constitutive phase-shifter elements exhibit strong electromagnetic coupling between neighbors,the design requires a global optimization methodology that considers the non-local interactions.Here,we propose a global evolutionary optimization approach to inverse design non-local metasurfaces.The optimal designs are experimentally validated,demonstrating the highest efficiencies for the thinnest transmissive metalenses reported to-date for visible light.In a departure from conventional design methods based on the search of a library of pre-determined and independent meta-atoms,we take full advantage of the strong interactions among nanoresonators to improve the focusing efficiency of metalenses and demonstrate that efficiency improvements can be obtained by lowering the metasurface filling factors.展开更多
基金supported as part of the Joint Center for Energy Storage Research,an Energy Innovation Hub funded by the U.S.Department of Energy,Office of Science,Basic Energy Sciencesthe supported by U.S.National Science Foundation(Grant No.2120559)。
文摘Fluorine-free electrolytes have attracted great attention because of its low-cost and environmental friendliness. However, so far, little is known about the solution structures of these electrolytes. Here,we compare the solvation phenomenon of sodium tetraphenylborate(NaBPh_(4)) salt dissolved in organic solvents of propylene carbonate(PC), 1,2-dimethoxyethane(DME), acetonitrile(ACN) and tetrahydrofuran(THF). Small-angle X-ray scattering(SAXS) reveals a unique two-peak structural feature in this saltconcentrated PC electrolyte, while solutions using other solvents only have one scattering peak.Molecular dynamics(MD) simulations further reveal that there are anion-based clusters in addition to the short-range charge ordering in the concentrated NaBPh4/PC electrolyte. Raman spectroscopy confirms the existence of considerable contact ion pairs(CIPs). This work emphasizes the importance of global and local structural analysis, which will provide valuable clues for understanding the structureperformance relationship of electrolytes.
基金This work was performed at the Center for Nanoscale Materials,a U.S.Department of Energy Office of Science User Facility,and supported by the U.S.Department of Energy,Office of Science,under Contract No.DE-AC02-06CH11357This research used resources of the National Energy Research Scientific Computing Center,a U.S.Department of Energy Office of Science User Facility,supported by the U.S.Department of Energy,Office of Science,under Contract No.DE-AC02-05CH11231.
文摘Conventional metasurfaces have demonstrated efficient wavefront manipulation by using thick and high-aspect-ratio nanostructures in order to eliminate interactions between adjacent phase-shifter elements.Thinner-than-wavelength dielectric metasurfaces are highly desirable because they can facilitate fabrication and integration with both electronics and mechanically tunable platforms.Unfortunately,because their constitutive phase-shifter elements exhibit strong electromagnetic coupling between neighbors,the design requires a global optimization methodology that considers the non-local interactions.Here,we propose a global evolutionary optimization approach to inverse design non-local metasurfaces.The optimal designs are experimentally validated,demonstrating the highest efficiencies for the thinnest transmissive metalenses reported to-date for visible light.In a departure from conventional design methods based on the search of a library of pre-determined and independent meta-atoms,we take full advantage of the strong interactions among nanoresonators to improve the focusing efficiency of metalenses and demonstrate that efficiency improvements can be obtained by lowering the metasurface filling factors.
