Further enhancing the effective absorption bandwidth (EAB) and the harsh-environment stability of high-entropy alloy (HEA) electromagnetic-wave absorbing (EMA) materials is of great practical significance and broad application prospects. A new type of sulfur (S)-dissolved HEA EMA material was developed in this work. The flaky FeCoNiCuSx (x = 0, 0.05, 0.10, 0.20) HEAs were successfully prepared by a mechanochemical process. The phase structure, magnetic properties, corrosion resistance, oxidation resistance and EMA performances of the FeCoNiCuSx HEAs were investigated in detail and it was found that the introduction of S significantly optimized the impedance matching and achieved excellent EMA performances. The results showed that S10 (FeCoNiCuS0.10) had a minimum reflection loss (RL) of −65.20 dB and a wide EAB of 6.89 GHz. And the S20 (FeCoNiCuS0.20) achieved an ultra-wide EAB of 7.00 GHz and an RL of −55.40 dB in the C-band. In addition, the FeCoNiCuSx HEAs also exhibited excellent corrosion resistance. This work not only demonstrated the potential application of S-dissolved HEAs in the EMA field in harsh environments, but also provided new ideas for optimizing the electromagnetic impedance matching of HEAs.
Solubilities of SO 2 have been determined in four biobased solvents (BBSs) at temperatures between 293.15 K and 323.15 K with 10 K intervals and pressure scope of (0–120.0) kPa using isochoric saturation method. The BBSs were selected from butyl lactate (BL), glyceryl triacetate (GT), triethyl citrate (TEC), and acetyl triethyl citrate (ATEC). Henry’s constants and thermodynamic properties such as Gibbs free energy , enthalpy and entropy of dissolution were derived from the solubility data. The gravimetric solubilities of SO 2 in BBSs were in the range of (0.07–8.52) mol.kg −1 and changed with the sequence of GT > BL > TEC ≈ ATEC. All the dissolution enthalpies were negative at each condition. The performances of SO 2 absorption in these solvents were further compared with those in some ionic liquids as well as common absorbents. The results illustrated that present BBSs possessed the potentiality as SO 2 absorbents due to their relatively large absorption ability, small absorption enthalpy, low toxicity, and biodegradability.
Although employing solid polymer electrolyte (SPE) in all-solid-state lithium/sulfur (ASSLS) batteries is a promising approach to obtain a power source with both high energy density and safety, the actual performance of SPE-ASSLS batteries still lag behind conventional lithium/sulfur batteries with liquid ether electrolyte. In this work, combining characterization methods of X-ray photoelectron spectroscopy, in situ optical microscopy, and three-electrode measurement, a direct comparison between these two battery systems is made to reveal the mechanism behind their performance differences. In addition to polysulfides, it is found that the initial elemental sulfur can also dissolve into and diffuse through the SPE to reach the anode. Different from the shuttle effect that causes uniform corrosion on the anode in a liquid electrolyte, dissolved sulfur species in SPE unevenly passivate the anode surface and lead to the inhomogeneous Li + plating/stripping at the anode/SPE solid-solid interface. Such inhomogeneity eventually causes void formation at the interface, which leads to the failure of SPE-ASSLS batteries. Based on this understanding, a protection interlayer is designed to inhibit the shuttling of sulfur species, and the modified SPE-ASSLS batteries show much-improved performance in cycle life.
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