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Entering voltage hysteresis in phase-separating materials : revealing the electrochemical signature of the intraparticle phase-separated state
Tomaž Katrašnik, Jože Moškon, Klemen Zelič, Igor Mele, Francisco Ruiz-Zepeda, Miran Gaberšček, 2023, izvirni znanstveni članek

Povzetek: Hysteresis is a general phenomenon regularly observed in various materials. Usually, hysteretic behavior is an intrinsic property that cannot be circumvented in the non-equilibrium operation of the system. Herein, we show that, at least with regard to the hysteretic behavior of phase-separating battery materials, it is possible to enter (deeply) the hysteretic loop at finite battery currents. This newly observed electric response of the electrode, which is inherent to phase-separating materials, is, for the first time, related to its microscopic origin arising from a (significant) share of the active material residing in an intraparticle phase-separated state. This intriguing observation was further generalized by revealing that a phase-separating material can feature (significantly) different chemical potentials at the same bulk lithiation level and temperature when exposed to the same finite current and external voltage hysteresis. Therefore, the intraparticle phase-separated state significantly affected the DC and AC characteristics of the battery. The experimental evidence for entering the intraparticle phase-separated state is supported by thermodynamic reasoning and advanced modeling. The current findings will help advance the understanding, control, diagnostics, and monitoring of batteries composed of phase-separating materials while also providing pertinent motivation for the enhancement of battery design and performance.
Ključne besede: battery, phase-separating materials, Lithium iron phosphate, voltage hysteresis, intraparticle phase-separated
Objavljeno v DiRROS: 06.09.2023; Ogledov: 70; Prenosov: 36
.pdf Celotno besedilo (5,07 MB)
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The Incorporation of steel slag into belite-sulfoaluminate cement clinkers
Lea Žibret, Katarina Šter, Maruša Mrak, Mojca Loncnar, Sabina Dolenec, 2021, izvirni znanstveni članek

Povzetek: The potential use of steel slag from treated steel slag in belite-sulfoaluminate cements was investigated in this study. Cement clinkers with two phase compositions were synthesized, allowing the incorporation of different amounts of steel slag. The phase composition and microstructure of cement clinkers at three different sintering temperatures were studied by X-ray powder diffraction and the Rietveld method, as well as scanning electron microscopy with energy dispersive spectrometry. The results showed that the targeted phase composition of clinkers was achieved at a sintering temperature of 1250%C. However, a higher amount of perovskite instead of ferrite was detected in the clinker with a higher content of Ti-bearing bauxite. Apart from the main phases, such asbelite, calcium sulfoaluminate, and ferrite, several minor phases were identified, including mayenite, perovskite, periclase, and alkali sulfates. In both clinker mixtures, a higher content of MgO in the steelslags resulted in the formation of periclase. Furthermore, the hydration kinetics and compressive strength at 7 and 28 days were studied in two cements prepared from clinkers sintered at 1250%C. As evidenced by the results of isothermal calorimetry, the hydration kinetics were also influenced by the minor clinker phases. Cement with a higher content of calcium sulfoaluminate phase developed a higher compressive strength.
Ključne besede: cements, BCSA, steel slag, secundary row materials, microstructure, clinker phase
Objavljeno v DiRROS: 01.08.2023; Ogledov: 80; Prenosov: 37
.pdf Celotno besedilo (5,50 MB)
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