Nanosynthesis and Characterization of Cu_1.8Se_0.6S_0.4 as a Potential Cathode for Magnesium Battery Applications

Abstract

Copper selenide (Cu–Se) and copper sulfide (Cu–S) are promising cathodes for magnesium-ion batteries. However, the low electronic conductivity of Cu–Se system results in a poor rate capability and unsatisfactory cycling performance. Mg-ion batteries based on the Cu–S cathode exhibited large kinetic barriers during the recharging process owing to the presence of polysulfide species. This work attempts to circumvent this dilemma by doping Cu1.8Se by sulfur, which replaces the selenium in the CuSe lattice to form Cu1.8Se0.6S0.4 nanocrystalline powder. The presence of sulfur will increase the electronic conductivity, and the presence of selenium will mitigate the effect of polysulfide species that hinder the kinetics of Mg2+. Herein, a Cu1.8Se0.6S0.4 nanocrystalline powder was synthesized by the solid-state reaction, yielding a highly pure and stoichiometric powder. The crystallographic structure of the nanopowder and the conversion-type storage mechanism have been attested via ex situ X-ray diffraction and energy-dispersive X-ray analysis. The nanocrystalline feature of Cu1.8Se0.6S0.4 was demonstrated by high-resolution transmission electron microscopy. An apparent surface morphology change during the charging/discharging process has been visualized by a field emission scanning electron microscope. Diffuse reflectance spectroscopy has discussed the variation of the band gap during charging and discharging. The full Mg/Cu1.8Se0.6S0.4 cells presented an initial discharge capacity of 387.99 mAh g– 1 at a current density of 0.02 mA cm–2; moreover, they show moderate diffusion kinetics with ≈ 10–15 cm–2 s–1.

Engineering the optical, and dielectric properties of (PVA: PVP)/BaSnO3 polymer nanocomposites as promising films for optoelectronics and energy storage applications

“…The lattice constants and the volume of the unit cell of PVA/PVP filled with various concentrations of BaSnO 3 can be evaluated via the below equations. 56 :…”

Life Aging Effect as a Conditioning Process that Regulates the Performance of the Halogen-Free Mg Electrolyte

“…Rechargeable magnesium batteries are nominated to be one of the most promising next-generation “beyond Li-ion” because of the merits of using Mg anodes, which offers a low reduction potential (−2.36 V vs NHE), low dendritic growth, low air sensitivity, high volumetric capacity ∼3833 mA h cm –3 (twice of the Li metal), sustainability, safety, and low cost. − Unfortunately, the high charge density for the Mg 2+ ion (120 C·mm –3 ) generates a strong electrostatic interaction with its surrounding, resulting in sluggish Mg 2+ ion-diffusion kinetics in most materials and high reactivity of Mg metal toward electrolyte species . Magnesium–sulfur (Mg–S) battery chemistry bypasses the intercalation issues via adapting conversion reaction results in superior theoretical specific capacity (1673 mA h g –1 ) .…”