High-Voltage and Fast-Charging Lithium Cobalt Oxide Cathodes: From Key Challenges and Strategies to Future Perspectives

Lithium-ion batteries(LIBs)with the“double-high”characteristics of high energy density and high power density are in urgent demand for facilitating the development of advanced portable electronics.However,the lithium ion(Li+)-storage performance of the most commercialized lithium cobalt oxide(LiCoO_(2),LCO)cathodes is still far from satisfactory in terms of high-voltage and fast-charging capabilities for reaching the double-high target.Herein,we systematically summarize and discuss high-voltage and fast-charging LCO cathodes,covering in depth the key fundamental challenges,latest advancements in modification strategies,and future perspectives in this field.Comprehensive and elaborated discussions are first presented on key fundamental challenges related to structural degradation,interfacial instability,the inhomogeneity reactions,and sluggish interfacial kinetics.We provide an instructive summary of deep insights into promising modification strategies and underlying mechanisms,categorized into element doping(Li-site,cobalt-/oxygen-site,and multi-site doping)for improved Li+diffusivity and bulkstructure stability;surface coating(dielectrics,ionic/electronic conductors,and their combination)for surface stability and conductivity;nanosizing;combinations of these strategies;and other strategies(i.e.,optimization of the electrolyte,binder,tortuosity of electrodes,charging protocols,and prelithiation methods).Finally,forward-looking perspectives and promising directions are sketched out and insightfully elucidated,providing constructive suggestions and instructions for designing and realizing high-voltage and fast-charging LCO cathodes for next-generation double-high LIBs.

Transient multi-physics behavior of an insert high temperature superconducting no-insulation coil in hybrid superconducting magnets with inductive coupling

A transient multi-physics model incorporated with an electromagneto-thermomechanical coupling is developed to capture the multi-field behavior of a single-pancake(SP)insert no-insulation(NI)coil in a hybrid magnet during the charging and discharging processes.The coupled problem is resolved by means of the finite element method(FEM)for the magneto-thermo-elastic behaviors and the Runge-Kutta method for the transient responses of the electrical circuits of the hybrid superconducting magnet system.The results reveal that the transient multi-physics responses of the insert NI coil primarily depend on the charging/discharging procedure of the hybrid magnet.Moreover,a reverse azimuthal current and a compressive hoop stress are induced in the insert NI coil during the charging process,while a forward azimuthal current and a tensile hoop stress are observed during the discharging process.The induced voltages in the insert NI coil can drive the currents flowing across the radial turns where the contact resistance exists.Therefore,it brings forth significant Joule heat,causing a temperature rise and a uniform distribution of this heat in the coil turns.Accordingly,a thermally/mechanically unstable or quenching event may be encountered when a high operating current is flowing in the insert NI coil.It is numerically predicted that a quick charging will induce a compressive hoop stress which may bring a risk of buckling instability in the coil,while a discharging will not.The simulations provide an insight of hybrid superconducting magnets under transient start-up or shutdown phases which are inevitably encountered in practical applications.

High Permeability in Broadband of Co-sputtered [Fe-Fe_(20)Ni_(80)/Cr]_(n) Multilayer Films

To achieve high microwave permeability in wide-band for the micron-thick magnetic films,[Fe-Fe_(20)Ni_(80)/Cr]_(n) multilayer structure was proposed by co-sputtering Fe and FeNi to form the magnetic layers and Cr to form the interlayers.The multilayer structure contributes to the high permeability by reducing the coercivity and diminishing out-of-plane magnetization.The maximum imaginary permeability of[Fe-Fe_(20)Ni_(80)/Cr]_(n) multilayer film reaches a large value of 800 at 0.52 GHz even though its overall thickness exceeds 1μm.Besides,the magnetic resonance frequency of the multilayer film can be modulated from 0.52 to 1.35 GHz by adjusting the sputtering power of Fe from 0 to 86 W,and its bandwidth for μ’’>200(Δf) is as large as 2.0 GHz.The desirable broad Δf of magnetic permeability,which can be well fitted by the Landau-Lifshitz-Gilbert equations,is due to dual magnetic resonances originated from double magnetic phases of Fe and FeNi that are of different saturation magnetization.The micron-thick multilayer films with high permeability in extended waveband are promising candidate for electromagnetic noise suppression application.

First-principles study of structural and electronic properties of multiferroic oxide Mn_(3)TeO_(6) under high pressure

Mn_(3)TeO_(6)(MTO) has been experimentally found to adopt a P2_(1)/In structure under high pressure,which exhibits a significantly smaller band gap compared to the atmospheric R3 phase.In this study,we systematically investigate the magnetism,structural phase transition,and electronic properties of MTO under high pressure through first-principles calculations.Both R3 and P2_(1)/n phases of MTO are antiferromagnetic at zero temperature.The R3 phase transforms to the P2_(1)/n phase at 7.5 8 GPa,accompanied by a considerable volume collapse of about 6.47%.Employing the accurate method that combines DFT+U/and GW,the calculated band gap of R3 phase at zero pressure is very close to the experimental values,while that of the P2_(1)/n phase is significantly overestimated.The main reason for this difference is that the experimental study incorrectly used the Kubelka-Munk plot for the indirect band gap to obtain the band gap of the P2_(1)/n phase instead of the Kubelka-Munk plot for the direct band gap.Furthermore,our study reveals that the transition from the R3 phase to the P2_(1)/n phase is accompanied by a slight reduction in the band gap.

Development of a high-repetition-rate lumped-inductance kicker magnet prototype for the beam switchyard of SHINE

The Shanghai high-repetition-rate X-ray free-electron laser and extreme light facility(SHINE)operates at a maximum repetition rate of 1 MHz.Kicker magnets are key components that distribute electron bunches into three different undulator lines in a bunch-by-bunch mode.The kicker field width must be less than the time interval between bunches.A lumpedinductance kicker prototype was developed using a vacuum chamber with a single-turn coil.The full magnetic field strength was 0.005 T.This paper presents the requirements,design considerations,design parameters,magnetic field calculations,and measurements of the kicker magnets.The relevant experimental results are also presented.The pulse width of the magnetic field was approximately 600 ns,and the maximum operation repetition rate was 1 MHz.The developed kicker satisfies the requirements for the SHINE project.Finally,numerous recommendations for the future optimization of kicker magnets are provided.

Discovery of controllable high Chern number quantum anomalous Hall state in tetragonal lattice FeSIn

Quantum anomalous Hall(QAH) insulators have excellent properties driven by fancy topological physics, but their practical application is greatly hindered by the observed temperature of liquid nitrogen, and the QAH insulator with high Chern number is conducive to spintronic devices with lower energy consumption. Here, we find that monolayer Fe SIn is a good candidate for realizing the QAH phase;it exhibits a high magnetic transition temperature of 221 K and tunable C = ±2 with respect to magnetization orientation in the y–z plane. After the application of biaxial strain, the magnetic axis shifts from the x–y plane to the z direction, and the effect of the high C and ferromagnetic ground state on the stress is robust. Also, the effect of correlation U on C has been examined. These properties are rooted in the large size of the Fe atom that contributes to ferromagnetic kinetic exchange with neighboring Fe atoms. These findings demonstrate monolayer Fe SIn to be a major template for probing novel QAH devices at higher temperatures.

Analysis of clinical characteristics of leptomeningeal metastasis with band-like high signal in the brainstem

Objective:The aim was to analyse the clinical features of leptomeningeal metastasis with banded high signal in the brainstem.Methods:In this paper,we report two cases of lung adenocarcinoma with soft meningeal metastasis,collected from the First Affiliated Hospital of Hainan Medical College,and searched the databases of CNKI,Wanfang,VIP,PubMed,Web of Science,and other databases which reported the MRI manifestation of"brainstem bandlike high signal",and collected the patients'past medical history,symptoms,signs,genetic findings,cerebrospinal fluid manifestation,treatment,and prognosis.Result:A total of 28 patients were included,of whom 26 had a history of lung adenocarcinoma and 2 were found to have occupational changes in the lungs.Magnetic resonance imaging(MRI)showed a band-like high signal in the ventral part of the brainstem on T2-FLAIR,symmetrical on both sides,which could extend to the cerebellar peduncles,with high signals on diffusion-weighted imaging(DWI),low signals on apparent diffusion coefficient(ADC),and long T1 signals on T1-weighted imaging,long T2 signals on T2 weighted imaging,and no long T2 signals on enhancement scan.T1-weighted imaging was a long T1 signal,T2-weighted imaging was a long T2 signal,and no enhancement was seen on enhanced scanning.Conclusion:It is important to recognize leptomeningeal metastasis of lung cancer,and the non-enhancing band of high signal in the brainstem on T2-FLAIR and DWI is likely to be the characteristic manifestation of leptomeningeal metastasis of non-small cell lung cancer.

High complex anal fistula managed by the modified transanal opening of the intersphincteric space via the inter-sphincteric approach:A case report

BACKGROUND High complex anal fistulas are epithelialized tunnels,with the main fistula piercing above the deep external sphincter and the internal opening approaching the dentate line.Conventional surgical procedures for high complex anal fistulas remove most of the external sphincter and damage the anorectal ring.Postoperative loss of anal function can cause physical and mental damage.Transanal opening of the intersphincteric space(TROPIS)is an effective procedure that completely preserves the external anal sphincter.However,its clinical application is limited by challenges in the localization of the internal opening of a fistula and the high risk of complications.On the basis of our clinical experience,we modified the TROPIS procedure for the treatment of treating high complex anal fistulas.CASE SUMMARY A patient with a high complex anal fistula located above the anorectal ring underwent modified TROPIS,which involved sepsis drainage and identification of the internal opening in the intersphincteric space.The patient with the high complex anal fistula recovered well postoperatively,without any postoperative complications or anal dysfunction.Anal function returned to normal after 17 months of follow-up.CONCLUSION The modified TROPIS procedure is the most minimally invasive surgery for anal fistulas that minimally impairs anal function.It allows the complete removal of infected anal glands and reduces the risk of postoperative complications.Modified TROPIS via the intersphincteric approach is an alternative sphincter-preserving treatment for high complex anal fistulas.

Quantification of trace amounts of impurities in high purity cobalt by high resolution inductively coupled plasma mass spectrometry

A An analytical method using high resolution inductively coupled plasma mass spectrometry （HR-ICP-MS） for rapid simultaneous determination of 24 elements （Be, Mg, A1, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn Sb, Ba, Pt, Au, and Pb） in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCI. The matrix effects because of the presence of excess HCI and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination were tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits were 0.016-1.50 ].tg·g^-1, the recovery ratios were 92.2%-111.2%, and the RSD was less than 3.6%. The method was accurate, quick, and convenient. It was applied to the determination of trace impurities in high purity cobalt with satisfactory results.

Quantification of Trace Amounts of Impurities in High Purity Cobalt by High Resolution Inductively Coupled Plasma Mass Spectrometry

An analytical method using high resolution inductively coupled plasma mass spectrometry （HR-ICP-MS） for rapid simultaneous determination of Be, Mg, Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn, Sb, Ba, Pt, Au and Pb in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCl. The matrix effects due to the presence of excess HCl and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination was tested and discussed. Correction for matrix effects, Sc, Rh and Bi were used as internal standards. The detection limits is 0.003-0.57 μg/g, the recovery ratio is 92.2%-111.2%, and the RSD is less than 3.6%. The method is accurate, quick and convenient. It has been applied to the determination of trace impurities in high purity cobalt with satisfactory results.

High Energy and High Coercivity Sintered NdFeB Magnets by Low Oxygen Process

Using ball milling and single direction pressing, we can produce high performance NdFeB sintered magnets. The oxygen content of sintered magnets can be controlled under 1500xl0^-6 and the magnetic performance can be improved by using low oxygen processing. The high preformance NdFeB sintered magnets with Br=(1.4 ± 0.2)T, iHc>796 kA/m and (BH)max=(390± 16) kJ/m^3, have been batch produced.

Study on Key Techniques for Producing High Performance NdFeB Sintered Permanent Magnets

High energy products (BH) max of 365 and 310 kJ·m -3 with intrinsic coercivity iH c of 1640 kA·m -1 of NdFeB sintered magnets were produced. Some new techniques were applied, such as thin NdFeB ingot technique, narrow particle distribution on jet mill, low oxygen content control and high aligned magnetic field press. It is necessary to produce thin NdFeB ingot with fine flake crystal, narrow particle distribution, the average size of NdFeB powders less than 4.0 μm, uniform microstructure, high oriented Nd 2Fe 14B small grains, and finally high performance NdFeB sintered magnets were prepared.

Surface-mediated iron on porous cobalt oxide with high energy state for efficient water oxidation electrocatalysis

Surface engineering of active materials to generate desired energy state is critical to fabricate high-performance heterogeneous catalysts.However, its realization in a controllable level remains challenging. Using oxygen evolution reaction(OER) as a model reaction, we report a surface-mediated Fe deposition strategy to electronically tailor surface energy states of porous Co_(3)O_(4)(Fe-pCo_(3)O_(4)) for enhanced activity towards OER. The Fe-pCo_(3)O_(4) exhibits a low overpotential of 280 mV to reach an OER current density of 100 mA cm^(-2), and a fast-kinetic behavior with a low Tafel slop of 58.2 mV dec^(-1), outperforming Co_(3)O_(4)-based OER catalysts recently reported and also the noble IrO_(2). The engineered material retains 100% of its original activity after operating at an overpotential of 350 m V for 100 h. A combination of theoretical calculations and experimental results finds out that the surface doped Fe promotes a high energy state and desired coordination environment in the near surface region, which enables optimized OER intermediates binding and favorably changes the rate-determining step.

Simultaneous determination of seven impurities in high-purity cobalt oxide by ICP-AES after matrix separation using 1-nitroso-2-naphthol as a precipitant

A method was developed for the simultaneous determination of seven trace impurities (Cd, Mn, Pb, Zn, Cu, Fe and Ni) in high purity cobalt oxide by ICP AES. The matrix effect was eliminated by preci pitation with 1 nitroso 2 naphthol. The matrix effect of cobalt on the absorptions of trace impurities, the effects of reaction time, pH value, dosage of precipitant on the formation of cobalt 1 nitroso 2 naphthol complex, the effects of hydrochloric acid on the stability of this complex and masking of elements were studied. Recoveries of the impurities in spiked sample are from 90% to 110% with a precision of 1.1% 5.0% RSD. The detection limits of the seven elements are in the range of 0.01 0.24μg/g. The method can be applied to the analysis of high purity cobalt metal, cobalt oxide and other cobalt compounds.

Numerical analysis of arc-droplet behavior in thin wire high current MAG welding with magnetic control

High efficiency welding has always been one of the hot research subjects at home and overseas. Aiming at the problem of unstable droplet rotating spray transfer process in 450 A thin wire metal active gas arc(MAG) welding, a three-dimensional arc-droplet coupled model is established in this paper on the base of fluid dynamics to conduct numerical analysis for droplet transfer behavior with external magnetic controlled MAG welding, and used high-speed camera system to verify the simulation results. The results indicate that without external magnetic field, the droplet is transferred by the way of rotating spray, the arc is changeable and the spatter is serious. The electromagnetic force accelerates the radial liquid beam rotation under direct current(DC) magnetic field, and increases the angle between liquid beam and welding wire axis. Meanwhile, the rotation frequency of the liquid beam reaches 400 Hz, the area of arc column and heat loss increase under DC magnetic field. Based on the alternating magnetic field, the arc is the “bell shaped”, the arc stiffness raises, its temperature achieves 26 000 K, and the maximum speed of the liquid stream beam can reach 500 m/s. And the droplet transfer is more stable, the spatter significantly reduces, and welding quality is effectively improved.

STUDIES ON PROCESS AND STABILITY OF BONDED Sm_2TM_(17)MAGNETS WITH HIGH COERCIVITY AND HIGH ENERGY PRODUCT

The process of the epoxy-bonded Sm_2TM_(17) magnets includes:(1)after melting,the ingots are treated by solid soluiion,and then aged and pulverized;(2)the obtained alloy powder is mixed with epoxy resin bind- er;(3)the mixture is pressed in a magnetic field;(4)the compacts are cured.When the SmCo_(4.9)Fe_(2.7)Cu_(0.54)Zr_(0.13) alloy is heat treated and pressed with optimum pressing parameters,the high quality bonded magnets with B_r=8250 G,_iH_c=13000 Oe,and(BH)_(max)=16MGOe can be obtained.The stability of the magnets is studied also.The irreversible loss of O.C.(open circuit)remanence B_r in the temperature range between 25 and 150℃,is less than 4%.The average temperature coefficient at temperatures between 25 and 70℃ is-0.03%/℃.The magnets obtained have heat resistance up to 130℃ even in long-term service, and have good corrosion resistance in acid,alkali and salt solutions.

Low-field, high-gradient NMR shows diffusion contrast consistent with localization or motional averaging of water near surfaces

Nuclear magnetic resonance(NMR)measurements of water diffusion have been extensively used to probe microstructure in porous materials,such as biological tissue,however primarily using pulsed gradient spin echo(PGSE)methods.Low-field single-sided NMR systems have built-in static gradients(SG)much stronger than typical PGSE maximum gradient strengths,which allows for the signal attenuation at extremely high b-values to be explored.Here,we perform SG spin echo(SGSE)and SG stimulated echo(SGSTE)diffusion measurements on biological cells,tissues,and gels.Measurements on fixed and live neonatal mouse spinal cord,lobster ventral nerve cord,and starved yeast cells all show multiexponential signal attenuation on a scale of b with significant signal fractions observed at b×Do>1 with b as high as 400 ms/um2.These persistent signal fractions trend with surface-to-volume ratios for these systems,as expected from porous media theory.An exception found for the case of fixed vs.live spinal cords was attributed to faster exchange or permeability in live spinal cords than in fixed spinal cords on the millisecond timescale.Data suggests the existence of multiple exchange processes in neural tissue,which may be relevant to the modeling of time-dependent diffusion in gray matter.The observed multi-exponential attenuation is from protons on water and not macromolecules because it remains proportional to the normalized signal when a specimen is washed with D20.The signal that persists to b×Do>1 is also drastically reduced after delipidation,indicating that it originates from lipid membranes that restrict water diffusion.The multiexponential or stretched exponential character of the signal attenuation at b×Do>1 appears mono-exponential when viewed on a scale of(b×Do)/3,suggesting it may originate from localization or motional averaging of water near membranes on sub-micron length scales.To try to disambiguate these two contributions,signal attenuation curves were compared at varying temperatures.While the curves align when normalizing them using the localization length scale,they separate on a motional averaging length scale.This supports localization as the source of non-Gaussian displacements,but this interpretation is still provisional due to the possible confounds of heterogeneity,exchange,and relaxation.Measurements on two types of gel phantoms designed to mimic extracellular matrix.one with charged functional groups synthesized from polyacrylic acid(PAC)and another with uncharged functional groups synthesized from polyacrylamide(PAM),both exhibit signal at b×Do>1,potentially due to water interacting with macromolecules.These preliminary finding motivate future research into contrast and attenuation mechanisms in tissue with low-field,high-gradient NMR。

Preparation of low cobalt high rate discharge hydrogen storage alloy MlNi_(3.85)Co_(0.45) Mn_(0.4)Al_(0.3)X_(0.1)(X=Mg,Si,Sn)

The non stoichiometric high rate discharge hydrogen storage alloys series MlNi 3.85 Co 0.45 Mn 0.4 Al 0.3 X 0.1 (Ml represents the lanthanum rich mischmetal, and X=Mg,Si,Sn) were prepared. The XRD and EDS results show that the high catalysis active miscellaneous La 2Ni 7 phase forms except for main phase LaNi 5 in the alloy body. The high rate discharge performance of hydrogen storage alloys electrode was improved because of the formation of La 2Ni 7 phase. The discharge capacities at 0.2C, 1C and 5C discharge rate reach 320 mAh·g -1 , 300 mAh·g -1 and 260 mAh·g -1 respectively when X is (Mg+Si). At the same scanning rate of circular volt—ampere testing, the surface anode oxidation peak current and peak area of the alloy containing (Mg+Si) electrode are far more larger than that of the high cobalt alloy MlNi 3.55 Co 0.75 Mn 0.4 Al 0.3 (AB 5). Furthermore, the cobalt content of the hydrogen storage alloy containing (Mg+Si) decreases by 40% and the high rate discharge performance improves obviously compare to high cobalt AB 5 alloys, it is promising that the hydrogen storage alloy containing (Mg+Si) becomes to an ideal dynamic battery cathode material.

Influence of magnetic field on power deposition in high magnetic field helicon experiment

Based on high magnetic field helicon experiment(HMHX), HELIC code was used to study the effect of different magnetic fields on the power deposition under parabolic distribution. This paper is divided into three parts: preliminary calculation, actual discharge experiment and calculation. The results of preliminary calculation show that a magnetic field that is too small or too large cannot produce a good power deposition effect. When the magnetic field strength is 1200 Gs,a better power deposition can be obtained. The actual discharge experiment illustrates that the change of the magnetic field will have a certain influence on the discharge phenomenon. Finally, the results of verification calculation successfully verify the accuracy of the results of preliminary simulation. The results show that in the actual discharge experiment, it can achieve the best deposition effect when the magnetic field is 1185 Gs.