Tm Ions Research Articles

Robust half-metallic spin-gap in Co2CrAl: doping and strain engineering

Half-metallic ferromagnetic (HM FM) materials with sizeable HM-gap have grabbed a lot of attention as they provide high spin-filtering and reduce the spin-flipping, which are necessary parameters for the manufacturing of magnetic memory devices. Herein, the effect of 3d transition metals (TM = Ti, V, Mn, and Fe) doping at Cr site on the electronic and magnetic properties of full-Heusler Co2CrAl compound is investigated utilizing ab-initio calculations. The negative formation energies for all doped systems confirm their structural stability at ambient pressure. Our results revealed that undoped and all the TM-doped systems exhibit a stable HM FM state. The Cr d yz and orbitals are mainly responsible for conductivity in the spin-majority channel with a small contribution from d xy / states in each case. It is also found the admixture of t 2g and e g characteristics of TM ions in the spin-magnetization density iso-surfaces, where magnetism is discussed by analyzing the electronic spin state configurations. Moreover, it is found that half-metallicity in all systems is robust and can be preserved by the compression/elongation of the unit cell volume up to 10%. Finally, the Bader charge analysis exhibits that all the motifs contain a mixture of covalent and ionic characteristics. Hence, the present work suggests that 3d TM-doped Co2CrAl structures are of great interest for the development of extremely capable data storage devices.

X-ray micro computed tomography and efficient electrochemical recovery of lanthanides on porous carbon cylinder electrodes

Porous carbon cylinder (PCC) electrodes were prepared by thermal treatment of used corn starch packaging materials at 800 °C under Ar condition. The recycled PCC electrodes were first used to successfully recover lanthanide (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) ions in a 0.1 M NaClO4 electrolyte by amperometry electrodeposition. The electrodeposited materials were characterized by scanning electron microscopy, X-ray diffraction crystallography, energy dispersive X-ray spectroscopy, Raman spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, temperature programmed reaction spectrometry, fluorescence (FL) spectroscopy, and real-time FL measurement for electrodeposition kinetic analysis. X-ray Micro computed tomography (X-ray micro-CT) was first successfully employed to examine open and closed pore 3D images for PCC before and after electrodeposition. Hydrogen storage property of PCC was also demonstrated. The present study showed very unique information for the preparation of PCC by recycling of used corn starch packaging materials, hydrogen storage, electrochemical recovery of lanthanide elements using the PCC, and inner and exterior 3D image processing of PCC using X-ray micro-CT.

Enhanced 1.5 µm emission of Tm3+ ions by co-doping Tb3+ ions in Y3Al5O12 ceramics

Tm3+ and Tb3+ co-doped Y3Al5O12 (YAG) ceramics were fabricated by high temperature solid state reaction under oxygen sintering. The absorption spectra, fluorescence spectra and fluorescence decay curves of Tm,Tb:YAG ceramics were measured. The spectral parameters of Tm,Tb:YAG ceramic were calculated. The lifetimes of Tm3+:3F4 level of Tm,Tb:YAG ceramics were calculated to be 11.28, 2.12, 1.24, 0.63 and 0.49 ms for the Tb3+ doping concentration of 0, 0.1, 0.2, 0.35 at 0.5 at%, respectively. The co-doping Tb3+ ion is a productive deactivator that could reduce the filling of 3F4 mainfold and enhance the emission of 3H4→3F4 transition. These results indicate that the addition of Tb3+ ions in Tm,Tb:YAG ceramic could be a promising technique for laser operation around 1.5 µm.

White up-conversion luminescence properties in Yb3+/Ho3+/Tm3+ tri-doped LiGaW2O8 phosphors

Monoclinic Yb 3+ -Tm 3+ -Ho 3+ tri-doped LiGaW 2 O 8 phosphors were prepared by the high temperature solid-state method. Upon the excitation of 980 nm, up-conversion (UC) blue emission in Tm 3+ /Yb 3+ co-doped and green and red emissions in Ho 3+ /Yb 3+ co-doped LiGaW 2 O 8 were observed, respectively. Bright white luminescence could be obtained by changing the doped concentrations of Tm 3+ ions in Tm 3+ /Ho 3+ /Yb 3+ co-doped LiGaW 2 O 8 . Moreover, based on the power dependence of the luminescence intensity, the UC mechanisms were studied. The results demonstrate that the multi-colors of the LiGaW 2 O 8 :Tm 3+ ,Ho 3+ ,Yb 3+ could be used in the fields of three-dimensional displays, solid-state lighting, and backlighting such as the white light generation. • The white UC properties of Yb 3+ -Tm 3+ -Ho 3+ tri-doped LiGaW 2 O 8 phosphors were researched for the first time. • Blue emission, green emission and red emission could be obtained in the LiGaW 2 O 8 : Tm 3+ , Ho 3+ , Yb 3+ phosphors. • Bright white luminescence upon 980 nm can be generated through an UC process in Tm 3+ /Ho 3+ /Yb 3+ co-doped LiGaW 2 O 8 .

Evaluating the impact of doping concentration on the performance of in-band pumped thulium-doped fiber amplifiers

Abstract This study is to investigate the impact of thulium concentration on the performance of in-band pumped thulium-doped silica fiber amplifiers with considering ion–ion interactions. Due to the fluorescence quenching in silica glass, the fluorescence lifetimes are required to compute at every Tm concentration. The theoretical model of fluorescence decay curves at in-band pumped thulium-doped silica fiber is used to determine the fluorescence lifetimes of the 3F4 and 3H4 levels. The calculated lifetimes of the commercially available thulium-doped silica fiber are 650 µs for 3F4 level and 14 µs for 3H4 level and these results are consentient well with the experimental reported results. The theoretical evaluating of the amplifier performance shows that the gain amplifier reduces with concentration increase because of the impact of both fluorescence quenching and the reverse cross-relaxation process. Thus, in contrast to pumping wavelength at 790 nm, there are negative effects of the high doping concentration of Tm ions on the amplifier performance at the in-band pumping scheme.

Photoluminescence of X-ray-Induced Divalent Tm Ions in BaLiF3:Tm3+ Nanocrystals

Photoluminescence of X-ray-Induced Divalent Tm Ions in BaLiF₃:Tm³⁺ Nanocrystals

Insights into the Enhanced Structural and Thermal Stabilities of Nb-Substituted Lithium-Rich Layered Oxide Cathodes.

Lithium-rich manganese-based layered oxides (LLOs) are considered to be the most promising cathode materials for next-generation lithium-ion batteries (LIBs) for their higher reversible capacity, higher operating voltage, and lower cost compared with those of other commercially available cathode materials. However, irreversible lattice oxygen release and associated severe structural degradation that exacerbate under high temperature and deep delithiation hinder the large-scale application of LLOs. Herein, we propose a strategy to stabilize the layered lattice framework and improve the thermal stability of cobalt-free Li1.2Mn0.53Ni0.27O2 by doping with 4d transition metal niobium (Nb). Detailed atomic-scale imaging, in situ characterization, and DFT simulations confirm that the induced strong Nb-O bonds stabilize the oxygen lattice framework and restrains the fracture of TM-O bonds, thereby inhibiting the release of lattice oxygen and the continuous migration of TM ions to the lithium layer during the cycle. Furthermore, Nb doping also promotes the surface rearrangement to form a Ni-enrichment layered/rocksalt heterogeneous interface to enhance surface structural stability. As a result, the Nb-doped material delivers a capacity of 181.7 mAh g-1 with retention of 85.5% after 200 cycles at 1C, extraordinary thermal stability with a capacity retention of 80.7% after 200 cycles at 50 °C, and superior rate capability.

Stabilizing Transition Metal Vacancy Induced Oxygen Redox by Co2+/Co3+ Redox and Sodium‐Site Doping for Layered Cathode Materials

AbstractAnionic redox is an effective way to boost the energy density of layer‐structured metal‐oxide cathodes for rechargeable batteries. However, inherent rigid nature of the TMO6 (TM: transition metals) subunits in the layered materials makes it hardly tolerate the inner strains induced by lattice glide, especially at high voltage. Herein, P2‐Na0.8Mg0.13[Mn0.6Co0.2Mg0.07□0.13]O2 (□: TM vacancy) is designed that contains vacancies in TM sites, and Mg ions in both TM and sodium sites. Vacancies make the rigid TMO6 octahedron become more asymmetric and flexible. Low valence Co2+/Co3+ redox couple stabilizes the electronic structure, especially at the charged state. Mg2+ in sodium sites can tune the interlayer spacing against O‐O electrostatic repulsion. Time‐resolved in situ X‐ray diffraction confirms that irreversible structure evolution is effectively suppressed during deep desodiation benefiting from the specific configuration. X‐ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations demonstrate that, deriving from the intrinsic vacancies, multiple local configurations of “□‐O‐□”, “Na‐O‐□”, “Mg‐O‐□” are superior in facilitating the oxygen redox for charge compensation than previously reported “Na‐O‐Mg”. The resulted material delivers promising cycle stability and rate capability, with a long voltage plateau at 4.2 V contributed by oxygen, and can be well maintained even at high rates. The strategy will inspire new ideas in designing highly stable cathode materials with reversible anionic redox for sodium‐ion batteries.

Stabilizing Transition Metal Vacancy Induced Oxygen Redox by Co2+ /Co3+ Redox and Sodium-Site Doping for Layered Cathode Materials.

Anionic redox is an effective way to boost the energy density of layer-structured metal-oxide cathodes for rechargeable batteries. However, inherent rigid nature of the TMO6 (TM: transition metals) subunits in the layered materials makes it hardly tolerate the inner strains induced by lattice glide, especially at high voltage. Herein, P2-Na0.8 Mg0.13 [Mn0.6 Co0.2 Mg0.07 □0.13 ]O2 (□: TM vacancy) is designed that contains vacancies in TM sites, and Mg ions in both TM and sodium sites. Vacancies make the rigid TMO6 octahedron become more asymmetric and flexible. Low valence Co2+ /Co3+ redox couple stabilizes the electronic structure, especially at the charged state. Mg2+ in sodium sites can tune the interlayer spacing against O-O electrostatic repulsion. Time-resolved in situ X-ray diffraction confirms that irreversible structure evolution is effectively suppressed during deep desodiation benefiting from the specific configuration. X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations demonstrate that, deriving from the intrinsic vacancies, multiple local configurations of "□-O-□", "Na-O-□", "Mg-O-□" are superior in facilitating the oxygen redox for charge compensation than previously reported "Na-O-Mg". The resulted material delivers promising cycle stability and rate capability, with a long voltage plateau at 4.2 V contributed by oxygen, and can be well maintained even at high rates. The strategy will inspire new ideas in designing highly stable cathode materials with reversible anionic redox for sodium-ion batteries.

Electrochemistry, Electrodeposition, and Photoluminescence of Eu (III)/Lanthanides (III) on Terpyridine-Functionalized Ti Nanospikes

Terpyridine-functionalized Ti nanospike electrodes (TiNS-SiTpy) were developed and applied to cyclic voltammetry and amperometry of Ln (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) ions and mixed Eu (III) + Ln (III) ions in a 0.1 M NaClO4 electrolyte. Electrodeposition was successfully performed over TiNS-SiTpy electrodes, which were fully examined by scanning electron microscopy, X-ray diffraction crystallography, Fourier-transform infrared spectroscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, photoluminescence (PL), and PL decay kinetics. The Gd and Tb ions were found to increase PL intensities with 10× longer lifetimes of 1.32 μs and 1.03 μs, respectively, compared with that of the electrodeposited Eu sample. The crystal phase and the oxidation states were fully examined for the mixed Ln (Eu + Gd and Eu + Tb) complex structures.

Luminescence and kinetics parameters of high sensitivity MgB4O7 phosphor co-doped with Tm and Dy

This work reports the luminescence and kinetics parameters of high sensitivity MgB4O7 phosphor co-doped with Tm and Dy ions (MgB4O7:Tm,Dy) obtained by the solution combustion technique. With the obtained material, sintered dosimeters in form of discs were made and subjected to 1223 K for 3 h and exposed to gamma radiation from a60Co source. It was found that these dosimeters show a sensitivity approximately 10 times higher than that shown by the commercial dosimeter TLD-100 (LiF:Mg,Ti). The kinetic parameters from three samples with different concentration of dopants were determined using the initial rise, peak shape and deconvolution methods. Initial rise and peak shape methods showed lower values than those found by the deconvolution method for the main peak (Peak 1). MgB4O7:Tm, Dy shows a wide linearity interval of TL response with respect to gamma dose and low coefficient of variability (1.5%). These results suggest that this new high sensitivity phosphor could be a promising material to be used in clinical dosimetry.

Structural and optical properties of transition metal ion-doped ordered mesoporous TiO2 prepared by chelating-assisted evaporation induced self-assembly method

This paper demonstrates the fabrication of highly ordered mesoporous titanium dioxide (OMT) with different transition metals (TM: Fe, Mn, and Ni) by employing a self-assembly surfactant template route. The ordered TM-loaded mesoporous TiO2 (TM-OMT) has uniform mesopores (3–5 nm pore diameter), and a crystalline framework is successfully prepared via soft template strategy by employing Pluronic® F127 triblock copolymer as a chelating and structural directing agent. The structural and optical characteristics of the TM-OMT hybrids have been examined by scanning electron microscopy (SEM), transmission electron microscope (TEM), XRD, N2-sorption isotherms, UV/visible diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS) reveals the successful incorporation of TM ions over the highly ordered mesostructured OMT. The XRD pattern evidenced that the obtained TM-doped OMT samples are pure anatase of the crystalline phase. By employing TEM analysis, the average particle size is estimated to be 2–2.7 nm, whereas diffraction patterns have evidenced the polycrystalline features of the mesoporous structure. The bandgap energy of TM-doped mesoporous decreases according to the particular metal and its amount due to the reduced particle size. This cost-effective method provides the exceptional potential to tune the optical features for TM-doped mesoporous TiO2 materials for its optoelectronic applications and show more significant promise for energy conversion technologies.

Sustainable approach of batch and continuous biosorptive systems for praseodymium and thulium ions removal in mono and binary aqueous solutions

With advancement of technologies in most of the sectors, the market requirement for the rare earth elements (REEs) increasing at a rapid rate. Hence, it is vital to recover REEs from wastewater. Thus, in the present study, biosorptive uptake of praseodymium (Pr(III)) and thulium (Tm(III)) ions from mono and binary solutions using polysulfone-immobilized Turbinaria conoides (PITC) were examined for the first time The sorption of Pr(III) and Tm(III) ions were performed in batch and column biosorption systems. The biosorptional uptakes of PITC for Pr(III) and Tm(III) in mono solution were found as 1.14 and 1.23 mmol/g, respectively. The equilibrium biosorption data of the mono system were examined through the Langmuir and Freundlich isotherms, whereas data of binary biosorption experiments were checked with Sheindorf–Rebhun–Sheintuch and extended Langmuir isotherm model. The desorption efficiency of PITC in batch system showed recovery of Pr(III) and Tm(III) more than 95.5% up to 5 cycles. Continuous biosorption models like the Thomas, Yoon–Nelson and modified dose–response were employed to understand continuous biosorption behavior, and model constants were determined. The column desorption efficiency were observed as 98.9% (Pm(III)) and 99.5% (Tm(III)). Good biosorption capacity, desorption and reuse potential of PITC illustrated the environmental friendliness and scalable features.

The participation of cyanobacteria in reducing the concentration of fusariotoxins and heavy metal ions in aqueous solutions (model experiments)

Aim. The goal was to establish the effect of soil cyanobacteria (CB) Fischerella muscicola, Nostoc paludosum and Nostoc linckia on change in the concentration of heavy metal ions (HM) and fusariotoxins in aqueous media.Material and Methods. In order to plot the kinetics of sorption by dry biomass of CB Fischerella muscicola and Nostoc paludosum of copper(II), lead(II) and cadmium ions from solutions with a concentration of 10‐4mol/L, the method of potentiometry with ion‐selective electrodes was used. The concentration of fusariotoxins in the filtrate of the contact medium of Fischerella muscicola CB and Nostoc linckia with F. culmorumwas determined by HPLC.Results. The kinetics of sorption of TM ions by dry biomass of the CB isbest described by a modified second‐order model. According to the model, the sorption process limits the ion exchange reaction. In the presence of CB Fischerella muscicola and Nostoc linckia with a titer of 1.8∙106 cells/mL (1:100 dilution), a decrease in toxin and lycomarasmin in T‐2 medium occurs. However, this increases the concentration of fusaric acid and deoxynivalenol. In the variant where the titer of CB is equal to 1.8∙107cells/mL, the concentration of lycomarasmin is significantly reduced, while there is no change in the concentration of other fusariotoxins.Conclusion. Dry biomass of CB, having a high bisorption potential, can act as a good biosorbent with respect to copper(II), lead(II) and cadmium ions. A decrease in the concentration of fusariotoxins indicates the possibility of isolating active CB substances that can inhibit the biosynthesis of certain toxins of micromycetes of the genus Fusarium, reducing both the phytotoxicity of plant growth media and increasing the safety of crop production.

Electrochemical behaviors and electrodeposited materials of lanthanides (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) on terpyridine-functionalized Ti sheets

Electrochemical recovery of lanthanide metals has been a very important process for the treatments of nuclear and electronic wastes. In the present study, we established a big data set of lanthanide (III) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) ions on electrochemical behaviors and electrodeposition over bare and terpyridine-functionalized Ti sheets. Cyclic voltammetry and amperometry experiments were performed in a 0.1 M NaClO4 supporting electrolyte. The electrodeposited films were fully examined by scanning electron microscopy, Fourier-transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy, and photoluminescence. FT-IR and EDXS data confirmed that all the electrodeposited lanthanide materials were of a similar lanthanide complex. Photoluminescence imaging profiles were also obtained for selected Eu(III)-deposited films. The newly established data set could be very useful for understanding electrochemical behaviors of lanthanide ions, improvement of recovery method, and fabrication of catalyst electrode materials by electrodeposition.

Unrevealing the effects of low temperature on cycling life of 21700-type cylindrical Li-ion batteries

The synergic effects of the Li-plating, formation of thick and fissured SEI film, the uneven dissolution of TM ions, and the block of separator can rapidly deteriorate 21700-type cylindrical battery cycling performance at low temperature. • The failure mechanism of the 21700-type cylindrical Li-ion batteries were explored. • Voltage relaxation reveals severe lithium plating on graphite at low temperature. • Thick and fissured solid deposited/decomposed electrolyte mixture phase forms on the anode at low temperature. • The uneven dissolutions of TM-ions would be destructive to the cathode. • The deposition and decomposition of electrolytes would block pores of separators. The low-temperature performance of Li-ion batteries (LIBs) has important impacts on their commercial applications. Besides the metallic lithium deposition, which is regarded as one of the main failure mechanisms of the LIBs at low temperatures, the synergistic effects originating from the cathode, anode, electrolyte, and separators to the batteries are still not clear. Here, the 21700-type cylindrical batteries were evaluated at a wide range of temperatures to investigate the failure mechanism of batteries. Voltage relaxation, and the post-mortem analysis combined with the electrochemical tests, unravel that the capacity degradation of batteries at low temperature is related to the lithium plating at graphite anodes, the formation of unsatisfied solid deposited/decomposed electrolyte mixture phase on the anode, the precipitation of solvent in the electrolytes and the block of separator pores, and the uneven dissolved transition metal-ions from the cathode. We hope this finding may open up a new avenue to alleviate the capacity degradation of advanced LIBs at low temperatures and shed light on the development of outstanding low-temperature LIBs via simultaneous optimization of all the components including electrodes, electrolytes and separators.

Multinuclear transition metal-containing polyoxometalates constructed from Nb/W mixed-addendum precursors: synthesis, structures and catalytic performance.

Four new transition metal-containing Nb/W mixed-addendum POM trimers with the formula H19[M4(H2O)x(P2W15Nb3O62)3]·m(HCOOH)·nH2O (M = Cu, x = 15, m = 0, and n = 21, Cu-POM; M = Co, x = 7, m = 0, and n = 15, Co-POM; M = Mn, x = 7, m = 6, and n = 18, Mn-POM; and M = Zn, x = 7, m = 0, and n = 23, Zn-POM) have been synthesized by a solvothermal method in a water-ethanol mixed solvent. All the four compounds were characterized by single-crystal X-ray diffraction, powder X-ray diffraction (XRD), IR spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). These compounds can serve as efficient heterogeneous catalysts for the cyanosilylation of different carbonyl compounds under ambient temperature and solvent-free conditions, and Cu-POM shows much better catalytic performance than the other three compounds. The cycle experiment showed that Cu-POM can be reused for at least five cycles without significant loss of catalytic activity. The IR spectroscopy and XRD analysis revealed that Cu-POM can retain its integrity after catalysis.

The crystal structure and thermal expansion of novel substitutionally disordered Ca10TM0.5(VO4)7 (TM = Co, Cu) orthovanadates.

The whitlockite-related materials have attracted researchers' attention because of their potential application in various fields, especially in optoelectronics. In the present work, the structure of novel whitlockite-related oxides Ca10TM0.5(VO4)7 (TM = Co, Cu) is studied at room and high temperatures, using X-ray powder diffraction. These compounds form by fractional substitution of divalent transition metal atoms into the Ca3(VO4)2 lattice. Rietveld refinements provided the structural details. The lattice parameters are a = 10.78074(6) Å, c = 37.8196(2) Å, and V = 3806.67(4) Å3 for Ca10Co0.5(VO4)7 and a = 10.78710(7) Å, c = 37.8997(3) Å, and V = 3819.23(4) Å3 for Ca10Cu0.5(VO4)7. Structure refinement results show that among the five available sites (M1-M5), the M2+ ions select the M5 site. This finding is confirmed by analysis of interatomic distances: due to the difference in size between TM and Ca ions sharing the M5 site, the M5-O distance shortens by about 5.0% for Ca10Co0.5(VO4)7 and 2.7% for Ca10Cu0.5(VO4)7 with respect to the unsubstituted parent compound, Ca3(VO4)2. The observed trends in the crystallographic properties of the studied crystals are in line with those of previously reported structurally related phosphates, Ca10.5-xMx(PO4)7 (M = Mg or divalent transition metal). Moreover, the observed tendency for occupation of M5 by small divalent ions follows the earlier theoretical results. For cobalt and copper substituted orthovanadate and orthophosphate whitlockite related materials, a linear variation in the unit cell size is demonstrated. The common equation for evaluation of volume is applicable to the substitution of the two transition metals in orthovanadate and orthophosphate whitlockite related materials. Thermal expansion is investigated for both compounds. The variations of the lattice parameters and the thermal expansion coefficient with temperature are determined in the 300-810 K range. The lattice parameter, a, expands by 0.80% for Ca10Co0.5(VO4)7 and 0.74% for Ca10Cu0.5(VO4)7 in this range. The lattice parameter, c, enlarges by about 0.70% for both samples. In the studied temperature range, the volume thermal expansion coefficient of Ca10Co0.5(VO4)7 increases from 37.2 to 44.8 MK-1 and for Ca10Cu0.5(VO4)7, it increases from 35.1 to 45.2 MK-1; the observed expansion anisotropy is smaller than those of other related compounds.

Electrochemical Recovery and Behaviors of Rare Earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) Ions on Ni Sheets.

The electrochemical behaviors of rare earth (RE) ions have extensively been studied because of their high potential applications to the reprocessing of used nuclear fuels and RE-containing materials. In the present study, we fully investigated the electrochemical behaviors of RE(III) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) ions over a Ni sheet electrode in 0.1 M NaClO4 electrolyte solution by cyclic voltammetry between +0.5 and −1.5 V (vs. Ag/AgCl). Amperometry electrodeposition experiments were performed between −1.2 and −0.9 V to recover RE elements over the Ni sheet. The successfully RE-recovered Ni sheets were fully characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The newly reported recovery data for RE(III) ions over a metal electrode provide valuable information on the development of the treatment methods of RE elements.

High-Entropy-Type Cation-Disordered Rocksalt Cathodes for Li-Ion Batteries with Enhanced Capacity and Rate Capability

The recent success of Li-excess cation-disordered rocksalt (DRX) cathodes is providing an avenue to develop high energy density cathodes with abundant and low-cost metals, such as Mn, Fe and Ti. As they have high energy density, these cathode materials are currently the most viable strategy to address the resource issues of Co / Ni that will arise as conventional layered-type Li-ion cathodes are scaled towards multiple TWh of annual production. In DRX cathodes, facile Li transport relies mostly on the so-called “0-TM” 3D percolation channel, in which the intermediate tetrahedral sites are coordinated only by Li (no transition metals, TMs). The Li migration barrier along this “0-TM” channel is significantly lower compared to that of “1-TM” channel, where the intermediate tetrahedral sites are coordinated by 3 Li and 1 TM.The complexity of DRX cathodes lies in the fact that in most cases, they present various types of cation short-range order (SRO), which influences the frequency and connectivity of “0-TM” channels, thus controls the capacity and rate capability of DRX cathodes.Monte Carlo simulations have suggested that the presence of SRO in DRX cathodes generally leads to reduced Li percolation, when compared to that of a random arrangement of TM species.Inspired by the recent observations of nearly-random cation distribution in several high-entropy metal and oxide compounds, we have found that increasing the number of TM species in DRXs will improve Li transport properties by preventing the formation of a single dominant SRO type, resulting in improved capacity and high rate capability. We show that SRO in DRX cathodes systematically decreases as more TM components are added, and as a consequence, energy density and rate capability systematically increase. A DRX cathode with six TM species achieves 307 mAh g−1(955 Wh kg−1) at 20 mA g−1and retains more than 170 mAh g−1when cycling at 2,000 mA g−1. This success opens up a vast multi-dimensional chemical space to investigate, thus to facilitate further design in this high-entropy DRX space, we present a compatibility analysis of twenty-three different TM ions, and propose important design principles for advanced high-entropy DRX cathodes. The high compositional flexibility of these materials can also enable the use of less pure precursor materials. Reference Lee, J., Urban, A., Li, X., Su, D., Hautier, G., and Ceder, G. (2014). Unlocking the potential of cation-disordered oxides for rechargeable lithium batteries. Science 343, 519-522.Clément, R.J., Lun, Z., and Ceder, G. (2020). Cation-disordered rocksalt transition metal oxides and oxyfluorides for high energy lithium-ion cathodes. Energy & Environmental Science 13, 345-373.Lun, Z., Ouyang, B., Cai, Z., Clément, R.J., Kwon, D.-H., Huang, J., Papp, J.K., Balasubramanian, M., Tian, Y., McCloskey, B.D., et al.(2019). Design Principles for High-Capacity Mn-Based Cation-Disordered Rocksalt Cathodes. Chem .Lun, Z., Ouyang, B., Kitchaev, D.A., Clément, R.J., Papp, J.K., Balasubramanian, M., Tian, Y., Lei, T., Shi, T., McCloskey, B.D., et al.(2019). Improved Cycling Performance of Li-Excess Cation-Disordered Cathode Materials upon Fluorine Substitution. Advanced Energy Materials 9, 1802959.Ji, H., Urban, A., Kitchaev, D.A., Kwon, D.-H., Artrith, N., Ophus, C., Huang, W., Cai, Z., Shi, T., Kim, J.C., et al.(2019). Hidden structural and chemical order controls lithium transport in cation-disordered oxides for rechargeable batteries. Nature Communications 10, 592.Ouyang, B., Artrith, N., Lun, Z., Jadidi, Z., Kitchaev, D.A., Ji, H., Urban, A., and Ceder, G. (2020). Effect of Fluorination on Lithium Transport and Short-Range Order in Disordered-Rocksalt-Type Lithium-Ion Battery Cathodes. Advanced Energy Materials 10, 1903240.Lun Z., Ouyang, B.,Kwon, D.-H., Ha, Y., Foley, E.E., Huang, T.-Y., Cai, Z.,Kim, H., Balasubramanian, M.,Sun, Y., et al.(2020). Cation-disordered rocksalt-type high-entropy cathodes for Li-ion batteries. Nature Materials , in press. Figure 1