Doping Fe at the Co-tetrahedra site to improve the microstructure, optical, and Na-ion migrations in Na₂Co_1−xFe_xSiO₄

Abstract

Na2Co1−xFexSiO4 (NCFS)-based ceramics are some of the most promising alternatives to sodium-ion rechargeable batteries (SIBs).

Synthesis, optical properties and conduction mechanism study of α- and γ-NaMnO2 materials

“…The absorption coefficient was deduced from the absorbance using the following relationship: 31 α = 2303 A / d where d and A represent the thickness and absorbance, B is a constant, E g is the optical band gap, and hν is the energy of the incident photon. The direct optical gap energies were evaluated schematically by determining the point of intersection of the extrapolation of ( αhν ) 2 as a function of energy ( hν ) with the axis of irradiation energy ( hν ) (Fig.…”

Investigation of optical, dielectric properties and conduction mechanism of LiCo0.7Mn0.3O2

“…This value is extracted from the slope of the curve giving the variation of Ln (α) as a function of (hν) as shown in figure 5. We notice that the disorder in this compound is greater than that of other auxides such as monophosphates (such α-NaCoPO 4 : E U = 0.451 eV, β-NaCoPO 4 : E U = 0.41 eV and γ-NaCoPO 4 : E U = 0.64 eV [19]) and orthosilicates (such Na 2 CoSiO 4 : E U = 1.54 eV [20], Na 2 Co 1-x Fe x SiO 4 : E U = 1.34 and 1.72 eV [21]). This high value Eu at room temperature was due to the degree of defect present in this material.…”

Mixed polyanion Na2O-CuO-V2O5-P2O5 glass and glass ceramic cathode network: Relationship between structure and electrochemical performance

“…Among the various alternatives, Na-ion battery (SIB) technology has been shown to be the best viable substitute due to their inexpensive cost and practically limitless supply of sodium sources [4] . A good number of studies on Na-ion battery (SIB) technology have been conducted over the past ve years in an effort to meet the market's demand for smart electric-grid energy storage [5][6][7] .Since the crystalline cathode materials have a substantial impact on the sodium storage characteristics, however, commercialization of every crystalline cathode material network is, however, signi cantly constrained by issues with insu cient capacity, poor cycle performance, lower practical energy densities, and rate capability [8][9][10][11] . In order to meet these limitations, the research on mixed polyanion glass based (amorphous) cathode material systems have gotten much attention in very recent years as they offer good capacities about 300mAh/g capacities with reasonably good Coulombic e ciency [12] .…”