Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resista...Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.展开更多
The La-Mg-Ni-based A2B7-type La0.8-xNdxMg0.2Ni3.15Co0.2Al0.15 （x=0, 0.1, 0.2, 0.3, 0.4） electrode alloys were prepared by casting and annealing. The influences of partial substitution of Nd for La on the structure a...The La-Mg-Ni-based A2B7-type La0.8-xNdxMg0.2Ni3.15Co0.2Al0.15 （x=0, 0.1, 0.2, 0.3, 0.4） electrode alloys were prepared by casting and annealing. The influences of partial substitution of Nd for La on the structure and electrochemical performance of the as-cast and annealed alloys were investigated. It was found that the experimental alloys consist of two major phases, （La, Mg）2Ni7 phase with the hexagonal Ce2Ni7-type structure and LaNi5 phase with the hexagonal CaCu5-type structure, as well as some residual phase LaNi3 and NdNi5. The discharge capacity and high rate discharge ability （HRD） of the as-cast and annealed alloys first increase and then decrease with Nd content growing. The as-cast and annealed alloys （x=0.3） yield the largest discharge capacities of 380.3 and 384.3 mA·h/g, respectively. The electrochemical cycle stability of the as-cast and annealed alloys markedly grows with Nd content rising. As the Nd content increase from 0 to 0.4. The capacity retaining rate （S100） at the 100th charging and discharging cycle increases from 64.98% to 85.17% for the as-cast alloy, and from 76.60% to 96.84% for the as-annealed alloy.展开更多
The effect of KOH electrolyte concentration on low-temperature electrochemical properties of LaNi5 alloy electrodes at 233 K was studied. The results indicated that the electrolyte concentration had great influence on...The effect of KOH electrolyte concentration on low-temperature electrochemical properties of LaNi5 alloy electrodes at 233 K was studied. The results indicated that the electrolyte concentration had great influence on discharge capacity and discharge voltage plateau of LaNi5 alloy electrode at 233 K, and the highest discharge capacity and discharge voltage plateau were both obtained at 6 mol/L KOH. When the KOH electrolyte concentration changed from 5 to 9 mol/L at 233 K, the high rate discharge ability （HRD） had the same change tendency as the diffusion coefficient, but the exchange current density did not change significantly, which implied that hydrogen diffusion was the control step at low temperature 233 K for discharge process of LaNi5 alloy electrode.展开更多
The occurrence characteristics of shale oil are of great significance to the movability of shale oil.In this study,the occurrence characteristics of oil in the shale matrix at Funing Formation shale in Subei Basin wer...The occurrence characteristics of shale oil are of great significance to the movability of shale oil.In this study,the occurrence characteristics of oil in the shale matrix at Funing Formation shale in Subei Basin were quantitatively evaluated by organic geochemistry and microscopic pore structure characterization experiments.The Multiple Isothermal Stages Pyrolysis(MIS)experiment results show that the content of total oil,adsorbed oil,and free oil in the shales are 3.15-11.25 mg/g,1.41-4.95 mg/g,and 1.74-6.51 mg/g,respectively.among which the silicon-rich shale has the best oil-bearing.The relative content of free oil shows an increasing trend in pores with pore diameters greater than 3 nm.When the relative content of free oil reaches 100%,the pore size of silicon-rich shale is about 200 nm,while that of calcium-rich shale,clay-rich shale,and siliceous mixed shale is about 10 nm.The occurrence law of adsorbed oil is opposite to that of free oil,which indicates that shale oil will occur in the pores and fractures in a free state in a more extensive pore size range(>200 nm).This study also enables us to further understand the occurrence characteristics of shale oil under the interaction of occurrence state and occurrence space.展开更多
Lithium element has attracted remarkable attraction for energy storage devices, over the past 30 years. Lithium is a light element and exhibits the low atomic number 3, just after hydrogen and helium in the periodic t...Lithium element has attracted remarkable attraction for energy storage devices, over the past 30 years. Lithium is a light element and exhibits the low atomic number 3, just after hydrogen and helium in the periodic table. The lithium atom has a strong tendency to release one electron and constitute a positive charge, as Li<sup> </sup>. Initially, lithium metal was employed as a negative electrode, which released electrons. However, it was observed that its structure changed after the repetition of charge-discharge cycles. To remedy this, the cathode mainly consisted of layer metal oxide and olive, e.g., cobalt oxide, LiFePO<sub>4</sub>, etc., along with some contents of lithium, while the anode was assembled by graphite and silicon, etc. Moreover, the electrolyte was prepared using the lithium salt in a suitable solvent to attain a greater concentration of lithium ions. Owing to the lithium ions’ role, the battery’s name was mentioned as a lithium-ion battery. Herein, the presented work describes the working and operational mechanism of the lithium-ion battery. Further, the lithium-ion batteries’ general view and future prospects have also been elaborated.展开更多
The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studie...The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studied in alkaline medium（pH=11）. The catalyzed Fe-Cu process was found more effective on degradation of NBCs compared to Master Builder＇s iron. The reduction rate by the catalyzed Fe-Cu process decreased in the following order： nitrobenzene 〉4-chloro-nitrobenzene ≥m-dinitrobenzene ：〉 4-nitrophenol ≥2,4-dinitrotoluene 〉2-nitrophenol. The reduction rate by Master Builder＇s iron decreased in the following order： m-dinitrobenzene ≥4-chloro-nitrobenzene 〉4-nitrophenol 〉2,4-dinitrotoluene ≈nitrobenzene 〉2-nitrophenol. NBCs were reduced directly on the surface of copper rather than by the hydrogen produced at cathode in the catalyzed Fe-Cu process. The reduction was realized by the hydrogen produced at cathode and Fe（OH）2 in Master Builder＇s iron, It is an essential difference in reaction mechanisms between these two technologies. For this reason, the reduction by the catalyzed Fe-Cu depended greatly on NBC＇s electron withdrawing ability.展开更多
Among Al alloys,particularly 5000 series Al Mg and 6000 series Al Mg Si often used as marine materials have excellent corrosion resistance,low melting point,and thereby showing recycling availability when compared to ...Among Al alloys,particularly 5000 series Al Mg and 6000 series Al Mg Si often used as marine materials have excellent corrosion resistance,low melting point,and thereby showing recycling availability when compared to other metals.Variety experiments were conducted to select the most suitable material for marine environments.All electrochemical experiments were conducted in natural seawater.The corrosion test was performed in many methods such as anodic/cathodic polarization and Tafel analysis using multi-channel potentio/galvanostat WMPG 1000.As results,anodic and cathodic polarization behaviors indicate the characteristics of passive state and concentration polarization by reduction reaction in dissolved oxygen,which shows excellent electrochemical behaviors.Tafel analysis results show no significant difference but 5052-O alloy of various alloy materials indicates the lowest corrosion current density.Therefore,5052-O Al alloy presents most anti-corrosion material in marine environment.展开更多
The optimum corrosion protection potentials were examined for 5052-O Al alloy,which is mainly used in ships.Various electrochemical experiments were carried out and the surface morphologies of specimens were observed ...The optimum corrosion protection potentials were examined for 5052-O Al alloy,which is mainly used in ships.Various electrochemical experiments were carried out and the surface morphologies of specimens were observed by scanning electron microscopy（SEM） in order to determine the optimum corrosion protection potential to overcome pitting,corrosion,stress corrosion cracking（SCC）,and hydrogen embrittlement in sea water.An optimum protection potential range of-1.3 V to-0.7 V was determined under the application of an impressed current cathodic protection（ICCP） system.The low current densities were shown in the range of-1.3 V to-0.7 V in the electrochemical experiments and good specimen surface morphologies were observed after potentiostatic experiment.展开更多
The elcetrochemical characteristics of boron doped polycrystalline diamond thin film (BDF) electrode 4×4 mm 2 in size were studied using cyclic voltammetry and potentiostatic method. The diamond electrode exhib...The elcetrochemical characteristics of boron doped polycrystalline diamond thin film (BDF) electrode 4×4 mm 2 in size were studied using cyclic voltammetry and potentiostatic method. The diamond electrode exhibits adequate electrochemical activity and its response current changes linearly with K 3Fe(CN) 6 concentrations. The response current is proportional to the square root of the scan rate, reflecting mass transport controlled by planar diffusion. Stable mass transport can be quickly established within 4s. The BDF electrode provides good resolving power for the determination of lead and cadmium and gives satisfactory results in the analysis of pure water sample.展开更多
Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature therm...Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature thermal spray coating was performed with 85%Al-14.5%Zn-0.5%Zr for ship materials and various sealing materials were applied to improve its durability, and the electrochemical behavior and cavitation characteristics were observed. The results show that the sealing improves all the properties of the materials. Hybrid ceramic and fluoro-silicon sealing materials show good electrochemical characteristics, and the fluoro-silieon sealing material shows the best anti-cavitation characteristics.展开更多
Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilita...Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilitation.Mineral acids,citric acid and hybrid acid–gypsum additions were compared for their potential to transform and improve zeta potential,isoelectric point(IEP),surface protonation and active alkaline-OH groups,which are critical factors for further improvement of physicochemical and biological properties later.Isoelectric points of untransformed bauxite residue and six transformed derivatives were determined by using electroacoustic methods.Electrochemical characteristics were significantly improved by the amendments used,resulting in reduced IEP and-OH groups and decreased surface protonation for transformed residues.XRD results revealed that the primary alkaline minerals of cancrinite,calcite and grossular were transformed by the treatments.The treatments of citric acid and gypsum promoted the dissolution of cancrinite.From the SEM examination,citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of-OH groups on particle surfaces.The collective evidence suggested that citric acid and gypsum amendments may be used firstly to rapidly amend bauxite residues for alleviating the caustic conditions prior to the consideration of soil formation in bauxite residue.展开更多
The crystal structure, the phase composition and the electrochemical characteristics of Zr0.9Ti0.1(Ni1.1Mn0.7V0.2)x (x=0.90, 0.95, 1.00, 1.05) alloys were investigated by means of XRD, SEM, EDS and electrochemical mea...The crystal structure, the phase composition and the electrochemical characteristics of Zr0.9Ti0.1(Ni1.1Mn0.7V0.2)x (x=0.90, 0.95, 1.00, 1.05) alloys were investigated by means of XRD, SEM, EDS and electrochemical measurements. It was shown that all alloys are multiphase with C15 Laves phase as a main phase along with C14 phase and some secondary phases. And the amounts of the C14 phase and secondary phases in the four alloys increases with decreasing x. The results indicated that the various stoichiometric ratios have great effects on the electrochemical characteristics such as the maximum discharge capacity, discharge rate capability and self-discharge properties etc. for Zr0.9Ti0.1(Ni1.1Mn0.7 V0.2)X (x=0.90, 0.95, 1.00, 1.05) alloys. The hyper-stoichiometric Zr0.9 Ti0.1(N1.1Mn0.7 V0.20)1.05 exhibits the maximum discharge capacity of 332mAh-g-1. The C14 phase and secondary phases seems to improve discharge rate capability of the alloys.展开更多
The phase structure and electrochemical characteristics of Ml （（Ni3.55Co0.75Mn0.40Al0.30）sx （ x = 0.88, 0.92, 0.96, 1.00） hydrogen storage alloys were studied. The effect of the stoichiometric ratio on the phase ...The phase structure and electrochemical characteristics of Ml （（Ni3.55Co0.75Mn0.40Al0.30）sx （ x = 0.88, 0.92, 0.96, 1.00） hydrogen storage alloys were studied. The effect of the stoichiometric ratio on the phase structure and electrochemical characteristics was analyzed. The results of XRD reveal that all the alloys consist mainly of LaNi5 phase with the hexagonal CaCu5 structure. But a few of the diffraction peaks of La2Ni7 phase on XRD pattern are observed when x ≤ 0.92, and with decreasing x, the intensity of La2Ni7 diffraction peaks increases and the values of lattice parameters a and cell volume increase, c and c/a of LaNi5 phase decrease gradually. When x≥0.96, La2Ni7 phase disappears and the alloys become single CaCu5-type. The electrochemical tests show that the maximum discharge capacity, high rate dischargeability and low temperature dischargeability are improved to different degrees by adjusting the stoichiometric ratio.展开更多
The microstructure and electrochemical characteristics of Ml(NiCoMnAl) 5 alloys prepared by both the melt spinning method and the conventional induction melting were investigated and compared. SEM and XRD studies sh...The microstructure and electrochemical characteristics of Ml(NiCoMnAl) 5 alloys prepared by both the melt spinning method and the conventional induction melting were investigated and compared. SEM and XRD studies show that the microstructure of melt spinning alloys is columnar structure. With increasing melt spinning rate, the crystal grains become finer and preferentially grow along (111)[111] direction. The melt spinning and cast alloys belong to CaCu 5 type hexagonal crystal structure. The electrochemical measurements show that the initial capacities of melt spinning alloy electrodes are all above 210 mAh·g -1 with good activation behavior, reaching their maximum capacities after two charge discharge cycles. The maximum capacity (294 mAh·g -1 ) of melt spinning (10 m·s -1 ) alloy electrodes is as the same as that of as cast alloy electrode, and stability of charge discharge cycles of all melt spinning alloy electrodes is better than that of the as cast alloy electrodes. When charged at 600 mA·g -1 , the capacity of melt spinning (10 m·s -1 ) alloy electrode could reach 65% of its maximum capacity about 45 min with high rate discharge capability; but with the cycle number increasing, the stability of its capacity is less than that electrodes of melt spinning rate.展开更多
LiNi0.8Co0.2O2 particles were modified by Co3（PO4）2 coating. The effects of the Co3（PO4）2 coating on the structure and electrochemical properties of the LiNi0.8Co0.2O2 cathode material were investigated. The Co3...LiNi0.8Co0.2O2 particles were modified by Co3（PO4）2 coating. The effects of the Co3（PO4）2 coating on the structure and electrochemical properties of the LiNi0.8Co0.2O2 cathode material were investigated. The Co3（PO4）2 coating forms a thin layer on the surface of the LiNi0.8Co0.2O2 material and a solid solution by interacting with the LiNi0.8Co0.2O2 core material during calcination at 700℃ for 4 h. Charge-discharge experiment results show that the Co3（PO4）2 coating improves the cycling stability of the LiNi0.8Co0.2O2 cathode material. The capacity retention of the pristine LiNi0.8Co0.2O2 cathode after 50 cycles is 83.6%, whereas it is 91.7% in the case of the LiNi0.8Co0.2O2 cathode coated with 1 wt.% Co3（PO4）2. Storage tests of the 4.35 V charged electrode at 60℃ after a month show that the Co3（POg）2-coated sample exhibits good storage properties compared with the pristine sample.展开更多
The nonstoichiometric La-rich mischmetal (designated by MI)-based hydrogen storage alloy with a composition of MI(Ni0.64Co0.2Mn0.12Al0.04)(4.76) was prepared by arc melting and annealed at 1173 K for 10 h to investiga...The nonstoichiometric La-rich mischmetal (designated by MI)-based hydrogen storage alloy with a composition of MI(Ni0.64Co0.2Mn0.12Al0.04)(4.76) was prepared by arc melting and annealed at 1173 K for 10 h to investigate the effect of annealing treatment on the microstructure and electrochemical characteristics of the alloy. X-ray diffraction analysis showed that annealing can cause a release of the crystal lattice strain and an increase in amounts of the La2Ni7-type second phase in MI(Ni0.64Co0.20Mn0.12Al0.04)(4.76) alloy. Scanning electron microscopy and electron probe microanalysis examinations indicated that annealing leads to disappearance of the dendrite structure in the as-cast alloy, growth of crystal grain, and decrease of composition segregation. The annealing at 1173 K for 10 h flattened and extended the potential plateau and increased the maximum discharge capacity to 328 mA center dot h/g from 310 mA center dot h/g and the cycling life. The mechanism of the improvement in electrochemical characteristics was discussed based on the alloy microstructure change induced by annealing.展开更多
The partial substitution of Zr for La has been performed in order to ameliorate the electrochemical hydrogen storage performances of La–Mg–Ni based A2B7-type electrode alloys. The melt spinning technology was used t...The partial substitution of Zr for La has been performed in order to ameliorate the electrochemical hydrogen storage performances of La–Mg–Ni based A2B7-type electrode alloys. The melt spinning technology was used to prepare the La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1 (x=0, 0.05, 0.1, 0.15, 0.2) electrode alloys. The impacts of the melt spinning and the substituting La with Zr on the structures and the electrochemical hydrogen storage characteristics of the alloys were systemically investigated. The analysis of XRD and TEM reveals that the as-cast and spun alloys have a multiphase structure, composing of two main phases (La, Mg)2Ni7 and LaNi5 as well as a residual phase LaNi2. The electrochemical measurement indicates that both the substitution of Zr for La and the melt spinning ameliorate the electrochemical cycle stability of the alloys dramatically. Furthermore, the high rate discharge ability (HRD) of the as-spun (10 m/s) alloys notably declines with growing the amount of Zr substitution, while it first augments and then falls for the (x=0.1) alloy with rising the spinning rate.展开更多
VO2 powder was synthesized by a new soft-chemical method using formaldehyde as a reductant. The influences of pyrolysis temperature and time on the phase and morphology of grains were investigated by using thermal gra...VO2 powder was synthesized by a new soft-chemical method using formaldehyde as a reductant. The influences of pyrolysis temperature and time on the phase and morphology of grains were investigated by using thermal gravimeter/differential thermal analysis(TG/DTA), X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy and scanning electron microscope(SEM). The positive electrode discharge performances of Li-B/LiCl-KCl/VO2 thermal battery at 500 ℃ were studied. The results show that the product is mainly non-crystal when the precursor of VO2 is heated below 300 ℃. VO2(B) appears and transits into VO2(R) irreversibly as the heating temperature rises. The open-circle voltage of VO2 is 2.6 V (vs Li-B), and the initial discharge voltage of 100 mA/cm2 at 500 ℃ is 2.52 V. The specific capacities of 100 mA/cm2 and 200 mA/cm2 at cut-off voltage of 1.4 V are 449 A·s/g and 539 A·s/g, respectively.展开更多
Electrochemical behavior of chemical mechanical polishing of copper with oxide passive film was studied by electrochemical measurement technologies. Dependences of polarization curves and electrochemical parameters, t...Electrochemical behavior of chemical mechanical polishing of copper with oxide passive film was studied by electrochemical measurement technologies. Dependences of polarization curves and electrochemical parameters, the rate of formation or removal of passive film of copper on film modifier KClO 3 were investigated. The rules of dependences of corrosion potentials and corrosion current densities on polishing pressure and rotation rate were obtained. It is discovered that the rates of formation and removal of passive film of copper are enhanced, while the polishing pressure and rotation rate are reduced. The experiments show that the CMP processes decrease Tafel slope, increase electron transfer coefficient of anode reaction and decrease the activation energy of corrosion reaction of copper, thereby the corrosion processes are accelerated. The results indicate that CMP slurry recipe, which is composed of NaAc NaOH medium, using KClO 3 as passive film modifier and nano sized γ Al 2O 3 as abrasive, is feasible and reasonable. The technological conditions are 100 r/min, 16 kPa.展开更多
The olivine-type lithium iron phosphate(LiFePO_(4))cathode material is promising and widely used as a high-performance lithium-ion battery cathode material in commercial batteries due to its low cost,environmental fri...The olivine-type lithium iron phosphate(LiFePO_(4))cathode material is promising and widely used as a high-performance lithium-ion battery cathode material in commercial batteries due to its low cost,environmental friendliness,and high safety.At present,LiFePO_(4)/C sec-ondary batteries are widely used for electronic products,automotive power batteries,and other occasion-related applications with good thermal stability,stable cycle performance,and low room-temperature self-discharge rate.However,LiFePO_(4)-based battery applications are seriously limited when they are operated in a cold climate.This outcome is due to a considerable decrease in Li+transport capabilities within the elec-trode,particularly leading to a dramatic decrease in the electrochemical capacity and power performance of the electrolyte.Therefore,the design of low-temperature electrolytes is important for the further commercial application of LiFePO_(4) batteries.This paper reviews the key factors for the poor low-temperature performance of LiFePO_(4)-based batteries and the research progress of low-temperature electrolytes.Spe-cial attention is paid to electrolyte components,including lithium salts,cosolvents,additives,and the development of new electrolytes.The factors affecting the anode are also analyzed.Finally,according to the current research progress,some viewpoints are summarized to provide suitable modification methods and research suggestions for improving the practicability of LiFePO_(4)/C commercial batteries at low temperat-ures in the future.展开更多
基金funded by the Science and Technology Research and Development Plan of the China State Railway Group Company Limited(No.N2023J053).
文摘Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.
基金Projects(51161015,50961009)supported by the National Natural Science Foundations of ChinaProject(2011AA03A408)supported by the National Hi-tech Research and Development Program of ChinaProjects(2011ZD10,2010ZD05)supported by the Natural Science Foundation of Inner Mongolia,China
文摘The La-Mg-Ni-based A2B7-type La0.8-xNdxMg0.2Ni3.15Co0.2Al0.15 （x=0, 0.1, 0.2, 0.3, 0.4） electrode alloys were prepared by casting and annealing. The influences of partial substitution of Nd for La on the structure and electrochemical performance of the as-cast and annealed alloys were investigated. It was found that the experimental alloys consist of two major phases, （La, Mg）2Ni7 phase with the hexagonal Ce2Ni7-type structure and LaNi5 phase with the hexagonal CaCu5-type structure, as well as some residual phase LaNi3 and NdNi5. The discharge capacity and high rate discharge ability （HRD） of the as-cast and annealed alloys first increase and then decrease with Nd content growing. The as-cast and annealed alloys （x=0.3） yield the largest discharge capacities of 380.3 and 384.3 mA·h/g, respectively. The electrochemical cycle stability of the as-cast and annealed alloys markedly grows with Nd content rising. As the Nd content increase from 0 to 0.4. The capacity retaining rate （S100） at the 100th charging and discharging cycle increases from 64.98% to 85.17% for the as-cast alloy, and from 76.60% to 96.84% for the as-annealed alloy.
基金the National Natural Science Foundation of China (NSFC 50571072)
文摘The effect of KOH electrolyte concentration on low-temperature electrochemical properties of LaNi5 alloy electrodes at 233 K was studied. The results indicated that the electrolyte concentration had great influence on discharge capacity and discharge voltage plateau of LaNi5 alloy electrode at 233 K, and the highest discharge capacity and discharge voltage plateau were both obtained at 6 mol/L KOH. When the KOH electrolyte concentration changed from 5 to 9 mol/L at 233 K, the high rate discharge ability （HRD） had the same change tendency as the diffusion coefficient, but the exchange current density did not change significantly, which implied that hydrogen diffusion was the control step at low temperature 233 K for discharge process of LaNi5 alloy electrode.
基金This work was financially supported by the National Natural Science Foundation of China(41972123,41922015)the Natural Science Foundation of Shandong Province(ZR2020QD036).
文摘The occurrence characteristics of shale oil are of great significance to the movability of shale oil.In this study,the occurrence characteristics of oil in the shale matrix at Funing Formation shale in Subei Basin were quantitatively evaluated by organic geochemistry and microscopic pore structure characterization experiments.The Multiple Isothermal Stages Pyrolysis(MIS)experiment results show that the content of total oil,adsorbed oil,and free oil in the shales are 3.15-11.25 mg/g,1.41-4.95 mg/g,and 1.74-6.51 mg/g,respectively.among which the silicon-rich shale has the best oil-bearing.The relative content of free oil shows an increasing trend in pores with pore diameters greater than 3 nm.When the relative content of free oil reaches 100%,the pore size of silicon-rich shale is about 200 nm,while that of calcium-rich shale,clay-rich shale,and siliceous mixed shale is about 10 nm.The occurrence law of adsorbed oil is opposite to that of free oil,which indicates that shale oil will occur in the pores and fractures in a free state in a more extensive pore size range(>200 nm).This study also enables us to further understand the occurrence characteristics of shale oil under the interaction of occurrence state and occurrence space.
文摘Lithium element has attracted remarkable attraction for energy storage devices, over the past 30 years. Lithium is a light element and exhibits the low atomic number 3, just after hydrogen and helium in the periodic table. The lithium atom has a strong tendency to release one electron and constitute a positive charge, as Li<sup> </sup>. Initially, lithium metal was employed as a negative electrode, which released electrons. However, it was observed that its structure changed after the repetition of charge-discharge cycles. To remedy this, the cathode mainly consisted of layer metal oxide and olive, e.g., cobalt oxide, LiFePO<sub>4</sub>, etc., along with some contents of lithium, while the anode was assembled by graphite and silicon, etc. Moreover, the electrolyte was prepared using the lithium salt in a suitable solvent to attain a greater concentration of lithium ions. Owing to the lithium ions’ role, the battery’s name was mentioned as a lithium-ion battery. Herein, the presented work describes the working and operational mechanism of the lithium-ion battery. Further, the lithium-ion batteries’ general view and future prospects have also been elaborated.
文摘The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studied in alkaline medium（pH=11）. The catalyzed Fe-Cu process was found more effective on degradation of NBCs compared to Master Builder＇s iron. The reduction rate by the catalyzed Fe-Cu process decreased in the following order： nitrobenzene 〉4-chloro-nitrobenzene ≥m-dinitrobenzene ：〉 4-nitrophenol ≥2,4-dinitrotoluene 〉2-nitrophenol. The reduction rate by Master Builder＇s iron decreased in the following order： m-dinitrobenzene ≥4-chloro-nitrobenzene 〉4-nitrophenol 〉2,4-dinitrotoluene ≈nitrobenzene 〉2-nitrophenol. NBCs were reduced directly on the surface of copper rather than by the hydrogen produced at cathode in the catalyzed Fe-Cu process. The reduction was realized by the hydrogen produced at cathode and Fe（OH）2 in Master Builder＇s iron, It is an essential difference in reaction mechanisms between these two technologies. For this reason, the reduction by the catalyzed Fe-Cu depended greatly on NBC＇s electron withdrawing ability.
基金Project supported by the Cooperative Promotion Center of Science & Technology of JEONNAM TECHNOPARKMinistry of Education,Science and Technology(MEST)through"The research & development support of JEONNAM southwest science park"
文摘Among Al alloys,particularly 5000 series Al Mg and 6000 series Al Mg Si often used as marine materials have excellent corrosion resistance,low melting point,and thereby showing recycling availability when compared to other metals.Variety experiments were conducted to select the most suitable material for marine environments.All electrochemical experiments were conducted in natural seawater.The corrosion test was performed in many methods such as anodic/cathodic polarization and Tafel analysis using multi-channel potentio/galvanostat WMPG 1000.As results,anodic and cathodic polarization behaviors indicate the characteristics of passive state and concentration polarization by reduction reaction in dissolved oxygen,which shows excellent electrochemical behaviors.Tafel analysis results show no significant difference but 5052-O alloy of various alloy materials indicates the lowest corrosion current density.Therefore,5052-O Al alloy presents most anti-corrosion material in marine environment.
文摘The optimum corrosion protection potentials were examined for 5052-O Al alloy,which is mainly used in ships.Various electrochemical experiments were carried out and the surface morphologies of specimens were observed by scanning electron microscopy（SEM） in order to determine the optimum corrosion protection potential to overcome pitting,corrosion,stress corrosion cracking（SCC）,and hydrogen embrittlement in sea water.An optimum protection potential range of-1.3 V to-0.7 V was determined under the application of an impressed current cathodic protection（ICCP） system.The low current densities were shown in the range of-1.3 V to-0.7 V in the electrochemical experiments and good specimen surface morphologies were observed after potentiostatic experiment.
文摘The elcetrochemical characteristics of boron doped polycrystalline diamond thin film (BDF) electrode 4×4 mm 2 in size were studied using cyclic voltammetry and potentiostatic method. The diamond electrode exhibits adequate electrochemical activity and its response current changes linearly with K 3Fe(CN) 6 concentrations. The response current is proportional to the square root of the scan rate, reflecting mass transport controlled by planar diffusion. Stable mass transport can be quickly established within 4s. The BDF electrode provides good resolving power for the determination of lead and cadmium and gives satisfactory results in the analysis of pure water sample.
基金Project supported by the Ministry of Education,Science Technology(MEST) and Korea Industrial Technology Foundation(KOTEF) through the Human Resource Training Project for Regional Innovation
文摘Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature thermal spray coating was performed with 85%Al-14.5%Zn-0.5%Zr for ship materials and various sealing materials were applied to improve its durability, and the electrochemical behavior and cavitation characteristics were observed. The results show that the sealing improves all the properties of the materials. Hybrid ceramic and fluoro-silicon sealing materials show good electrochemical characteristics, and the fluoro-silieon sealing material shows the best anti-cavitation characteristics.
基金Projects(41877511,41842020)supported by the National Natural Science Foundation of China
文摘Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilitation.Mineral acids,citric acid and hybrid acid–gypsum additions were compared for their potential to transform and improve zeta potential,isoelectric point(IEP),surface protonation and active alkaline-OH groups,which are critical factors for further improvement of physicochemical and biological properties later.Isoelectric points of untransformed bauxite residue and six transformed derivatives were determined by using electroacoustic methods.Electrochemical characteristics were significantly improved by the amendments used,resulting in reduced IEP and-OH groups and decreased surface protonation for transformed residues.XRD results revealed that the primary alkaline minerals of cancrinite,calcite and grossular were transformed by the treatments.The treatments of citric acid and gypsum promoted the dissolution of cancrinite.From the SEM examination,citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of-OH groups on particle surfaces.The collective evidence suggested that citric acid and gypsum amendments may be used firstly to rapidly amend bauxite residues for alleviating the caustic conditions prior to the consideration of soil formation in bauxite residue.
文摘The crystal structure, the phase composition and the electrochemical characteristics of Zr0.9Ti0.1(Ni1.1Mn0.7V0.2)x (x=0.90, 0.95, 1.00, 1.05) alloys were investigated by means of XRD, SEM, EDS and electrochemical measurements. It was shown that all alloys are multiphase with C15 Laves phase as a main phase along with C14 phase and some secondary phases. And the amounts of the C14 phase and secondary phases in the four alloys increases with decreasing x. The results indicated that the various stoichiometric ratios have great effects on the electrochemical characteristics such as the maximum discharge capacity, discharge rate capability and self-discharge properties etc. for Zr0.9Ti0.1(Ni1.1Mn0.7 V0.2)X (x=0.90, 0.95, 1.00, 1.05) alloys. The hyper-stoichiometric Zr0.9 Ti0.1(N1.1Mn0.7 V0.20)1.05 exhibits the maximum discharge capacity of 332mAh-g-1. The C14 phase and secondary phases seems to improve discharge rate capability of the alloys.
文摘The phase structure and electrochemical characteristics of Ml （（Ni3.55Co0.75Mn0.40Al0.30）sx （ x = 0.88, 0.92, 0.96, 1.00） hydrogen storage alloys were studied. The effect of the stoichiometric ratio on the phase structure and electrochemical characteristics was analyzed. The results of XRD reveal that all the alloys consist mainly of LaNi5 phase with the hexagonal CaCu5 structure. But a few of the diffraction peaks of La2Ni7 phase on XRD pattern are observed when x ≤ 0.92, and with decreasing x, the intensity of La2Ni7 diffraction peaks increases and the values of lattice parameters a and cell volume increase, c and c/a of LaNi5 phase decrease gradually. When x≥0.96, La2Ni7 phase disappears and the alloys become single CaCu5-type. The electrochemical tests show that the maximum discharge capacity, high rate dischargeability and low temperature dischargeability are improved to different degrees by adjusting the stoichiometric ratio.
文摘The microstructure and electrochemical characteristics of Ml(NiCoMnAl) 5 alloys prepared by both the melt spinning method and the conventional induction melting were investigated and compared. SEM and XRD studies show that the microstructure of melt spinning alloys is columnar structure. With increasing melt spinning rate, the crystal grains become finer and preferentially grow along (111)[111] direction. The melt spinning and cast alloys belong to CaCu 5 type hexagonal crystal structure. The electrochemical measurements show that the initial capacities of melt spinning alloy electrodes are all above 210 mAh·g -1 with good activation behavior, reaching their maximum capacities after two charge discharge cycles. The maximum capacity (294 mAh·g -1 ) of melt spinning (10 m·s -1 ) alloy electrodes is as the same as that of as cast alloy electrode, and stability of charge discharge cycles of all melt spinning alloy electrodes is better than that of the as cast alloy electrodes. When charged at 600 mA·g -1 , the capacity of melt spinning (10 m·s -1 ) alloy electrode could reach 65% of its maximum capacity about 45 min with high rate discharge capability; but with the cycle number increasing, the stability of its capacity is less than that electrodes of melt spinning rate.
基金the National Natural Science Foundation of China (No. 50604018)
文摘LiNi0.8Co0.2O2 particles were modified by Co3（PO4）2 coating. The effects of the Co3（PO4）2 coating on the structure and electrochemical properties of the LiNi0.8Co0.2O2 cathode material were investigated. The Co3（PO4）2 coating forms a thin layer on the surface of the LiNi0.8Co0.2O2 material and a solid solution by interacting with the LiNi0.8Co0.2O2 core material during calcination at 700℃ for 4 h. Charge-discharge experiment results show that the Co3（PO4）2 coating improves the cycling stability of the LiNi0.8Co0.2O2 cathode material. The capacity retention of the pristine LiNi0.8Co0.2O2 cathode after 50 cycles is 83.6%, whereas it is 91.7% in the case of the LiNi0.8Co0.2O2 cathode coated with 1 wt.% Co3（PO4）2. Storage tests of the 4.35 V charged electrode at 60℃ after a month show that the Co3（POg）2-coated sample exhibits good storage properties compared with the pristine sample.
文摘The nonstoichiometric La-rich mischmetal (designated by MI)-based hydrogen storage alloy with a composition of MI(Ni0.64Co0.2Mn0.12Al0.04)(4.76) was prepared by arc melting and annealed at 1173 K for 10 h to investigate the effect of annealing treatment on the microstructure and electrochemical characteristics of the alloy. X-ray diffraction analysis showed that annealing can cause a release of the crystal lattice strain and an increase in amounts of the La2Ni7-type second phase in MI(Ni0.64Co0.20Mn0.12Al0.04)(4.76) alloy. Scanning electron microscopy and electron probe microanalysis examinations indicated that annealing leads to disappearance of the dendrite structure in the as-cast alloy, growth of crystal grain, and decrease of composition segregation. The annealing at 1173 K for 10 h flattened and extended the potential plateau and increased the maximum discharge capacity to 328 mA center dot h/g from 310 mA center dot h/g and the cycling life. The mechanism of the improvement in electrochemical characteristics was discussed based on the alloy microstructure change induced by annealing.
文摘The partial substitution of Zr for La has been performed in order to ameliorate the electrochemical hydrogen storage performances of La–Mg–Ni based A2B7-type electrode alloys. The melt spinning technology was used to prepare the La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1 (x=0, 0.05, 0.1, 0.15, 0.2) electrode alloys. The impacts of the melt spinning and the substituting La with Zr on the structures and the electrochemical hydrogen storage characteristics of the alloys were systemically investigated. The analysis of XRD and TEM reveals that the as-cast and spun alloys have a multiphase structure, composing of two main phases (La, Mg)2Ni7 and LaNi5 as well as a residual phase LaNi2. The electrochemical measurement indicates that both the substitution of Zr for La and the melt spinning ameliorate the electrochemical cycle stability of the alloys dramatically. Furthermore, the high rate discharge ability (HRD) of the as-spun (10 m/s) alloys notably declines with growing the amount of Zr substitution, while it first augments and then falls for the (x=0.1) alloy with rising the spinning rate.
基金Project(50002015) supported by the National Natural Science Foundation of China
文摘VO2 powder was synthesized by a new soft-chemical method using formaldehyde as a reductant. The influences of pyrolysis temperature and time on the phase and morphology of grains were investigated by using thermal gravimeter/differential thermal analysis(TG/DTA), X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy and scanning electron microscope(SEM). The positive electrode discharge performances of Li-B/LiCl-KCl/VO2 thermal battery at 500 ℃ were studied. The results show that the product is mainly non-crystal when the precursor of VO2 is heated below 300 ℃. VO2(B) appears and transits into VO2(R) irreversibly as the heating temperature rises. The open-circle voltage of VO2 is 2.6 V (vs Li-B), and the initial discharge voltage of 100 mA/cm2 at 500 ℃ is 2.52 V. The specific capacities of 100 mA/cm2 and 200 mA/cm2 at cut-off voltage of 1.4 V are 449 A·s/g and 539 A·s/g, respectively.
文摘Electrochemical behavior of chemical mechanical polishing of copper with oxide passive film was studied by electrochemical measurement technologies. Dependences of polarization curves and electrochemical parameters, the rate of formation or removal of passive film of copper on film modifier KClO 3 were investigated. The rules of dependences of corrosion potentials and corrosion current densities on polishing pressure and rotation rate were obtained. It is discovered that the rates of formation and removal of passive film of copper are enhanced, while the polishing pressure and rotation rate are reduced. The experiments show that the CMP processes decrease Tafel slope, increase electron transfer coefficient of anode reaction and decrease the activation energy of corrosion reaction of copper, thereby the corrosion processes are accelerated. The results indicate that CMP slurry recipe, which is composed of NaAc NaOH medium, using KClO 3 as passive film modifier and nano sized γ Al 2O 3 as abrasive, is feasible and reasonable. The technological conditions are 100 r/min, 16 kPa.
基金supported by the National Natural Science Foundation of China (No. 52102470)Guangxi Innovation Driven Development Project (No. AA17204100)
文摘The olivine-type lithium iron phosphate(LiFePO_(4))cathode material is promising and widely used as a high-performance lithium-ion battery cathode material in commercial batteries due to its low cost,environmental friendliness,and high safety.At present,LiFePO_(4)/C sec-ondary batteries are widely used for electronic products,automotive power batteries,and other occasion-related applications with good thermal stability,stable cycle performance,and low room-temperature self-discharge rate.However,LiFePO_(4)-based battery applications are seriously limited when they are operated in a cold climate.This outcome is due to a considerable decrease in Li+transport capabilities within the elec-trode,particularly leading to a dramatic decrease in the electrochemical capacity and power performance of the electrolyte.Therefore,the design of low-temperature electrolytes is important for the further commercial application of LiFePO_(4) batteries.This paper reviews the key factors for the poor low-temperature performance of LiFePO_(4)-based batteries and the research progress of low-temperature electrolytes.Spe-cial attention is paid to electrolyte components,including lithium salts,cosolvents,additives,and the development of new electrolytes.The factors affecting the anode are also analyzed.Finally,according to the current research progress,some viewpoints are summarized to provide suitable modification methods and research suggestions for improving the practicability of LiFePO_(4)/C commercial batteries at low temperat-ures in the future.
