Polysulfide-mediated solvation shell reorganization for fast Li+ transfer probed by in-situ sum frequency generation spectroscopy

Understanding of interfacial Li$^+$ solvation shell structures and dynamic evolution at the electrode/electrolyte interface is requisite for developing high-energy-density Li batteries. Herein, the reorganization of Li$^+$ solvation shell at the sulfur/electrolyte interface along with the presence of a trace amount of lithium polysulfides is verified by in-situ sum frequency generation (SFG) spectroscopy together with density functional theory (DFT) calculations. Both the spectroelectrochemical and DFT calculation results reveal a strongly competitive anion adsorption of the polysulfide anion additive against the pristine electrolyte anion on the sulfur cathode surface, reorganizing the interfacial local solvation shell structure facilitating rapid Li ion transfer and conduction. Meanwhile, the evolution of the SFG signals along with the discharging/charging cycle exhibits improved reversibility, indicating the transformation of the inner Helmholtz plane layer into a stable molecular-layer polysulfide interphase rather than a dynamic diffusion layer. Consequently, applications in practical Li-S batteries reveal the capacity and cycling stability of the corresponding cells are significantly enhanced. Our work provides a methodology using in-situ SFG for probing solvation reorganization of charge carriers at electrochemical interfaces

Stress-strain model study of ferrous tailing concrete short column restraint by hooping

This study analyzed the stress–strain curve of stirrup restraint ferrous tailing concrete by test and theoretical analysis. Twenty short column in strength grade 5 are used in the test with WC30, WC35, WC40, WC45 and WC50. The stress–strain data is achieved after the axial compression behavior test. It is found from the stress–strain curve that the stress–strain relationship is similar with natural sand concrete. Moreover, the whole stress–strain curve equation of stirrup restraint ferrous tailing concrete is put forward. The calculation results show that the data calculating by the equation are in good agreement with the experimental data

Improving Solar Vapor Generation by Eliminating the Boundary Layer Inhibition Effect of Evaporator Pores

Solar-driven water evaporation is highly demanded in various applications. However, the pore structures of the solar evaporators are commonly randomly designed, which seriously hinder vapor diffusion and thus limit water producibility. Herein, the boundary layer inhibition effect is uncovered for the first time, and we propose that low-tortuosity channels with a reduced boundary layer thickness is adequate for breaking through the long-existing vapor diffusion limitation. As a demo, nature-inspired low-tortuosity channels are constructed for a solar evaporator. Due to elimination of the boundary layer inhibition, the vapor diffusion flux can easily escape from the evaporator, yielding an evaporation rate of 16.8 kg m–2 h–1 under a convective flow of 4.0 m s–1 and 1 sun irradiation. Moreover, the 3D radial interconnection of the channels enables stable water evaporation under an arbitrary direction of convective flow. Our work provides a promising solution to eliminate the boundary layer inhibition effect of a solar evaporator