In this paper, any two of the three anticorrosion agents, that is emulsifier (OP-10), soluble glass (Na2O·nSiO2) and glycerin (C3H8O3), were treated simultaneously on the surface of amorphous (a- ) MgNi + 5% Ml2M...In this paper, any two of the three anticorrosion agents, that is emulsifier (OP-10), soluble glass (Na2O·nSiO2) and glycerin (C3H8O3), were treated simultaneously on the surface of amorphous (a- ) MgNi + 5% Ml2Mg17(MI denotes the lanthanum-rich mish metal) electrode and the electrolyte. Effect of the synergistic anticorrosion treatment on charging/discharging cycle stability of the electrode was investigated. Contrasted with single treatment method, the cycling stability of the electrodes was further improved. The desirable synergistic anticorrosion method was that the electrode was treated by the soluble glass, and that OP-10 was added into the electrolyte. The cyclic voltammogram (CV) results of the electrode show clearly that the anticorrosion agent can change the electrochemical activity and mechanism of the electrode. The concentration of the anticorrosion agent in the electrolyte treated by the synergistic anticorrosion method was also investigated. The appropriate concentration of the anticorrosion agents in the electrolyte is 0.143% .展开更多
With the depletion of fossil fuels and global warming,there is an urgent demand to seek green,low-cost,and high-efficiency energy resources.Hydrogen has been considered as a potential candidate to replace fossil fuels...With the depletion of fossil fuels and global warming,there is an urgent demand to seek green,low-cost,and high-efficiency energy resources.Hydrogen has been considered as a potential candidate to replace fossil fuels,due to its high gravimetric energy density(142 MJ kg^(-1)),high abundance(H_(2)O),and environmentalfriendliness.However,due to its low volume density,effective and safe hydrogen storage techniques are now becoming the bottleneck for the"hydrogen economy".Under such a circumstance,Mg-based hydrogen storage materials garnered tremendous interests due to their high hydrogen storage capacity(~7.6 wt%for MgH_(2)),low cost,and excellent reversibility.However,the high thermodynamic stability(ΔH=-74.7 kJ mol^(-1)H_(2))and sluggish kinetics result in a relatively high desorption temperature(>300℃),which severely restricts widespread applications of MgH_(2).Nano-structuring has been proven to be an effective strategy that can simultaneously enhance the ab/de-sorption thermodynamic and kinetic properties of MgH_(2),possibly meeting the demand for rapid hydrogen desorption,economic viability,and effective thermal management in practical applications.Herein,the fundamental theories,recent advances,and practical applications of the nanostructured Mg-based hydrogen storage materials are discussed.The synthetic strategies are classified into four categories:free-standing nano-sized Mg/MgH_(2)through electrochemical/vapor-transport/ultrasonic methods,nanostructured Mg-based composites via mechanical milling methods,construction of core-shell nano-structured Mg-based composites by chemical reduction approaches,and multi-dimensional nano-sized Mg-based heterostructure by nanoconfinement strategy.Through applying these strategies,near room temperature ab/de-sorption(<100℃)with considerable high capacity(>6 wt%)has been achieved in nano Mg/MgH_(2)systems.Some perspectives on the future research and development of nanostructured hydrogen storage materials are also provided.展开更多
MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost characteristics.But some shortcomings are still existed:high...MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost characteristics.But some shortcomings are still existed:high operating temperature and poor hydrogen absorption dynamics,which limit its application.Porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres(NZC/Ni@CNT)is prepared by facile filtration and calcination method.Then the different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%)is added to the MgH_(2) by ball milling.Among the three samples with different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%),the MgH_(2)-5 wt%NZC/Ni@CNT composite exhibits the best hydrogen storage performances.After testing,the MgH_(2)-5 wt%NZC/Ni@CNT begins to release hydrogen at around 110℃ and hydrogen absorption capacity reaches 2.34 wt%H_(2) at 80℃ within 60 min.Moreover,the composite can release about 5.36 wt%H_(2) at 300℃.In addition,hydrogen absorption and desorption activation energies of the MgH_(2)-5 wt%NZC/Ni@CNT composite are reduced to 37.28 and 84.22 KJ/mol H_(2),respectively.The in situ generated Mg_(2)NiH_(4)/Mg_(2)Ni can serve as a"hydrogen pump"that plays the main role in providing more activation sites and hydrogen diffusion channels which promotes H_(2) dissociation during hydrogen absorption process.In addition,the evenly dispersed Zn and MgZn2 in Mg and MgH_(2) could provide sites for Mg/MgH_(2) nucleation and hydrogen diffusion channel.This attempt clearly proved that the bimetallic carbide Ni_(3)ZnC_(0.7) is a effective additive for the hydrogen storage performances modification of MgH_(2),and the facile synthesis of the Ni_(3)ZnC_(0.7)/Ni@CNT can provide directions of better designing high performance carbide catalysts for improving MgH_(2).展开更多
The effect of heat-treatment process on the properties of Mm0.8Mg0.2(NiCoAlMn)3.5 hydrogen storage alloy was discussed . The electrochemical properties such as cycling stability, activation property, and the plateau v...The effect of heat-treatment process on the properties of Mm0.8Mg0.2(NiCoAlMn)3.5 hydrogen storage alloy was discussed . The electrochemical properties such as cycling stability, activation property, and the plateau voltage of the alloy which was heat-treated in various temperatures and times had different changes during the cycle process, the optimum heat-treatment conditions of this alloy were determined by this work.展开更多
A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5...A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1). after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).展开更多
The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x <0.2 ...The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x <0.2 for Ml could improve its discharge capacity, but Ca substitution with x >0.2 could decrease the capacity. It was also found that Ca substitution deteriorates the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. In order to improve these properties of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 alloy electrode, the alloy was treated in 6 mol/L KOH+0.02 mol/L KBH 4 solution. The results showed that the surface treatment improves the electrochemical performances such as the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. :The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x <0.2 for Ml could improve its discharge capacity, but Ca substitution with x >0.2 could decrease the capacity. It was also found that Ca substitution deteriorates the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. In order to improve these properties of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 alloy electrode, the alloy was treated in 6 mol/L KOH+0.02 mol/L KBH 4 solution. The results showed that the surface treatment improves the electrochemical performances such as the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode.展开更多
Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/de...Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/desorption rate and excessive hydrogen absorption/desorption temperature limit the application of Mg-based hydrogen storage materials.The present paper reviews the advances in the research of Mg-based hydrogen storage film in recent years, including the advantage of the film, the function theory of fabricating method and its functional theory, and the influencing factors in the technological process. The research status worldwide is introduced in detail. By comparing pure Mg, Pd-caped Mg, nonpalladium capped Mg, and Mg alloy hydrogen storage films, an ideal tendency for producing Mg-based film is pointed out,for example, looking for a cheap metal element to replace the high-priced Pd, compositing Mg film with other hydrogen storage alloy of catalytic elements, and so on.展开更多
The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction.The catalysis of Co@C composites on the hydrogen storage behavior of Mg_(90)Ce_(5)Y_(5)alloy w...The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction.The catalysis of Co@C composites on the hydrogen storage behavior of Mg_(90)Ce_(5)Y_(5)alloy was investigated in detail by XRD,SEM,TEM,PCI,and DSC method.Because of the synergistic catalytic function of C and Co in C@Co nanocomposites,the Mg_(90)Ce_(5)Y_(5)alloy with 10 wt.%C@Co shows the excellent hydrogen absorption and desorption performances.Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300℃.Meanwhile,the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol^(-1)H_(2)after the addition of the C@Co composites.This positive effect attributes to the C layer with the high defect density and the Co nanoparticles,which reduces the energy barriers for the nucleation of Mg/MgH_(2)phase and the recombination of hydrogen molecule.Besides,the C@Co composites also improve the activation property of the Mg_(90)Ce_(5)Y_(5)alloy which was folly activated in the first cycle.Moreover,the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased.Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy,these differences are so small that the improvement on thermodynamics can hardly be seen.展开更多
The rapid development of electric vehicles demands the development of high performance nickel metal hydride battery that is able to endure high temperature. The discharge properties of Ti 0.7 Zr 0.5 V 0.2 Mn 1.8- x Ni...The rapid development of electric vehicles demands the development of high performance nickel metal hydride battery that is able to endure high temperature. The discharge properties of Ti 0.7 Zr 0.5 V 0.2 Mn 1.8- x Ni x ( x =0.4, 0.8, 1.1, 1.4, 1.7)hydrogen storage alloys was investigated and its phase composition was analyzed using X ray diffraction. The results show that the cycling life was improved as the content of nickel increases. When x =0.4, 0.8, 1.1 and 1.4, the main phase is MgZn 2 type C14 Laves phase and the second one is cubic TiNi phase. When x =1.7, the Laves phase structure disappears. EDAS analysis shows that the increase of nickel content is effective in suppressing the dissolution of vanadium component in alloys. [展开更多
Mg-based hydrogen storage alloys are considered as a promising candidate for hydrogen system because of its lightweight, high storage capacity, low price and rich mineral resources. In detail, we reviewed the preparat...Mg-based hydrogen storage alloys are considered as a promising candidate for hydrogen system because of its lightweight, high storage capacity, low price and rich mineral resources. In detail, we reviewed the preparation and properties of Mg-Ni-based hydrogen storage alloys. All kinds of attempts have been done to improve the hydriding and dehydriding behaviors. It is found that the partial substitution of foreign elements can decrease the hydrogen absorption temperature, especially the substitution of a more electronegative element, such as AI and Mn. Mechanical alloying (MA) and mechanical grinding (MG) are the most effective methods to improve the hydriding/dehydriding kinetics and electrochemical capacity, and decrease the desorption temperature. but the corrosion resistance is so poor that the 80% of maximum capacity is lost within ten cycles. Microencapsulation is a useful measurement for improving the corrosion resistance and electrocatalytic activity. fn order to improve the properties of the alloys for practical application, the alloys should have a large number of defects, which give activated sites, subsequently, MA, MG and electroless plating should be used to improve the hydriding/dehydriding kinetics and protect the surface of alloys, respectively. The new composite Mg-based alloys give a new way for the hydrogen storage material to practical application. Furthermore we put forward several problems which will be discussed in future.展开更多
A series of multi-component M1-based hydrogen storage alloys witha cobalt atomic ratio of 0.40-0.75 were prepared. The electrochemicalproperties under different charge-discharge conditions and PCTcharaceristics measur...A series of multi-component M1-based hydrogen storage alloys witha cobalt atomic ratio of 0.40-0.75 were prepared. The electrochemicalproperties under different charge-discharge conditions and PCTcharaceristics measured by electrochemical method were investigated.The addition of other alloying elements for partial substitution ofCo low- ers the hydrogen equilibrium pressure and discharge capacity,but improves the cycling stability and makes the alloys keep nearlythe same rate discharge capability and high-temperature dischargecapability as those of the compared alloy. The reasons werediscussed.展开更多
Mg-based hydrogen storage nanocomposites added with carbon nanotubes(CNTs) were prepared by mechanical milling under the atmosphere of hydrogen. The results show that because of their own excellent heat conductivity a...Mg-based hydrogen storage nanocomposites added with carbon nanotubes(CNTs) were prepared by mechanical milling under the atmosphere of hydrogen. The results show that because of their own excellent heat conductivity and good hydrogen storage ability, the carbon nanotubes improve the mass transfer and heat transfer properties of the Mg-based nanocomponents, thus enhancing the kinetic property of hydrogen absorption and desorption of the hydrogen storage nanocomposites, and raising the hydrogen storage capacity. Due to the addition of the carbon nanotubes, the milling stress in the process of preparing the Mg-based nanocomposites is reduced, the components can be closely bonded easily, and the additives can play better catalytic roles.展开更多
The kinetics equation of the Mg-based hydrogen storage alloys (Mg-Ni-MO) was established by the shell and shrinking core model. The total coefficients of the kinetics equation of the hydrogen absorption and desorption...The kinetics equation of the Mg-based hydrogen storage alloys (Mg-Ni-MO) was established by the shell and shrinking core model. The total coefficients of the kinetics equation of the hydrogen absorption and desorption process with shell diffusion as the controlling step were determined by semi-empirical and semi-theoretical methods, and the apparent activation energy of the hydrogen absorption process was obtained. The calculation results can well accord with the experimental data, and can well forecast the hydrogen storage capacity and absorption rate at different times. By using the kinetics equation, the effects of temperature and pressure on the hydrogen storage process can also be well understood. The kinetics equation is helpful for the design of the hydrogen storage container.展开更多
The effect of the hot-charging treatment on the performance of AB(2) and AB(5) hydrogen storage alloy electrodes was investigated. The result showed that the treatment can markedly improve the voltage plateau ratio (V...The effect of the hot-charging treatment on the performance of AB(2) and AB(5) hydrogen storage alloy electrodes was investigated. The result showed that the treatment can markedly improve the voltage plateau ratio (VPR), the high rate discharge ability (HRDA), the diffusion coefficient of hydrogen DH and the discharge capacity of the AB2 hydrogen storage alloy electrode. The SEM analysis showed that the hot-charging treatment brings about a Ni-rich surface due to the dissolution of Zr oxides. It is also very helpful for the improvement of the kinetic properties of AB2 hydrogen storage alloy electrode because the microcracking of the surface results in fresh surface. This can be the basic modification treatment for NiMH battery used in electric vehicles (EVs) in the future. But for AB(5) type alloys, the treatment has the disadvantage of impairing the comprehensive electrochemical properties, because the surface of the alloy may be corroded during the treatment. The mechanism of the surface modification of the electrode is also proposed.展开更多
Ti0.5Al0.25Ni0.25 alloy prepared by vacuum induction melting was studied.The phase composition was analyzed with X-ray technique and EDS analysis,and its electrochemical properties were investigated at various tempera...Ti0.5Al0.25Ni0.25 alloy prepared by vacuum induction melting was studied.The phase composition was analyzed with X-ray technique and EDS analysis,and its electrochemical properties were investigated at various temperatures.Electrochemical reaction kinetic parameters were also studied with proper electrochemical techniques.The influence of the secondary corrosion reaction on the anodic linear polarization measurement was also analyzed by theoretical simulation.The results show that,proper ball-milling with nickel powders is beneficial to electrochemical performance.The theoretical simulation proves that,the existence of the side reaction can disturb the measurement of electrochemical reaction kinetic parameters.展开更多
The impedance diagram of hdrogen storage electrodes(AH electrodes )displayed twosemicircles.Thelow frequency one is affected by cycle number and composition of MH electrodes.
The microstructures and electrode properties of Cr or Co-doped V2.1 TiNi0.5 Hf0.05M 0.113 (M=Cr, Co) hydrogen storage alloys were investigated. It is found that all alloys consist of a main phase of V-based solid so...The microstructures and electrode properties of Cr or Co-doped V2.1 TiNi0.5 Hf0.05M 0.113 (M=Cr, Co) hydrogen storage alloys were investigated. It is found that all alloys consist of a main phase of V-based solid solution with b.c.c. structure and a secondary phase of C14-type Laves phase with a three-dimensional network structure. After the doping of Cr or Co into V 2.1TiNi 0.5Hf 0.05, the abundance and unit cell volume of the main phase decrease, and those of the secondary phase increase. The electrochemical measurements show that the discharge capacities of Cr-doped V2.1 TiNi0.5 Hf0.05Cr 0.113 alloy and Co-doped V2.1 TiNi0.5 Hf0.05Co 0.113 alloy are less than that of V2.1 TiNi0.5 Hf0.05 alloy, but their cycle stability and high-rate dischargeability are improved markedly. The results show that Cr or Co doping into V2.1 TiNi0.5 Hf0.05 alloy is significantly beneficial for the cycling stability.展开更多
The influence of the addition of Cu(OH)2 to 6 mol/L KOH alkaline electrolyte on the electrochemical properties of La2Mg0.9Al0.1Ni7.5Co1.5 hydrogen storage alloy electrode was investigated by electron probe X-ray micro...The influence of the addition of Cu(OH)2 to 6 mol/L KOH alkaline electrolyte on the electrochemical properties of La2Mg0.9Al0.1Ni7.5Co1.5 hydrogen storage alloy electrode was investigated by electron probe X-ray microanalysis(EPMA),X-ray diffraction(XRD) and electrochemical measurements. EPMA micrographs and XRD patterns show that the surface of the hydride electrode is plated by metal copper film. The thickness and compactness of Cu film increase with the increment of charge-discharge cycle number. The copper film of the hydride electrode surface can keep the hydrogen storage alloy particle in the electrode interior from oxidizing availably. The addition of Cu(OH)2 to alkaline electrolyte lowers the activation property and the high rate dischargeability of the La2Mg0.9Al0.1Ni7.5Co1.5 hydride electrode,but has no negative effect on the maximum discharge capacity of the hydride electrode. Moreover,it is effective to improve the cyclic stability of the hydride electrode utilizing electrodeposit Cu film on the La2Mg0.9Al0.1Ni7.5Co1.5 hydride electrodes surface.展开更多
Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding c...Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding cycling kinetics and thermodynamic stability of the experimental alloys have been investigated in detail.The results show that the Mg-Ni-La alloys exhibit improved hydrogen storage cycling properties and can remain storage hydrogen above 5.5 wt%after 200 cycles.With the increase of cycling numbers,the dehydrogenation rates of the experimental samples increase firstly and then gradually decrease,and eventually maintain relative stable state.Microstructure observation reveals that powders sintering and hydrogen decrepitation both exist during hydrogen absorption/desorption cycles due to repeated volume expansion and contraction.Meanwhile,the in-situ formed LaH_(x)(x=2,3)and Mg_(2)Ni nanocrystallines stabilize the microstructures of the particles and hinder the powders sintering.After 200 cycles,the average particle size of the experimental samples decreases and the specific surface area apparently increases,which leads to the decomposition temperatures of MgH_(2)and Mg_(2)NiH_(4)slightly shift to lower temperatures.Moreover,Mg_(2)Ni and LaH_(x)(x=2,3)have been proven to be stable catalysts during long-term cycling,which can still uniformly distribute within the powders after 200 cycles.展开更多
基金Project supported by the National Natural Science Foundation of China (20363001) the Project in Specific Technological R & D Fund Program for Research Institutes from Ministry of Science and Technology of the PRC (2004EG113030)the Key Project in International Science and Technology Cooperation from Ministry of Science and Technology of the PRC (2005DFA50250)
文摘In this paper, any two of the three anticorrosion agents, that is emulsifier (OP-10), soluble glass (Na2O·nSiO2) and glycerin (C3H8O3), were treated simultaneously on the surface of amorphous (a- ) MgNi + 5% Ml2Mg17(MI denotes the lanthanum-rich mish metal) electrode and the electrolyte. Effect of the synergistic anticorrosion treatment on charging/discharging cycle stability of the electrode was investigated. Contrasted with single treatment method, the cycling stability of the electrodes was further improved. The desirable synergistic anticorrosion method was that the electrode was treated by the soluble glass, and that OP-10 was added into the electrolyte. The cyclic voltammogram (CV) results of the electrode show clearly that the anticorrosion agent can change the electrochemical activity and mechanism of the electrode. The concentration of the anticorrosion agent in the electrolyte treated by the synergistic anticorrosion method was also investigated. The appropriate concentration of the anticorrosion agents in the electrolyte is 0.143% .
基金support from the National Key Research&Development Program(2022YFB3803700)of ChinaNational Natural Science Foundation(No.52171186)financial support from the Center of Hydrogen Science,Shanghai Jiao Tong University。
文摘With the depletion of fossil fuels and global warming,there is an urgent demand to seek green,low-cost,and high-efficiency energy resources.Hydrogen has been considered as a potential candidate to replace fossil fuels,due to its high gravimetric energy density(142 MJ kg^(-1)),high abundance(H_(2)O),and environmentalfriendliness.However,due to its low volume density,effective and safe hydrogen storage techniques are now becoming the bottleneck for the"hydrogen economy".Under such a circumstance,Mg-based hydrogen storage materials garnered tremendous interests due to their high hydrogen storage capacity(~7.6 wt%for MgH_(2)),low cost,and excellent reversibility.However,the high thermodynamic stability(ΔH=-74.7 kJ mol^(-1)H_(2))and sluggish kinetics result in a relatively high desorption temperature(>300℃),which severely restricts widespread applications of MgH_(2).Nano-structuring has been proven to be an effective strategy that can simultaneously enhance the ab/de-sorption thermodynamic and kinetic properties of MgH_(2),possibly meeting the demand for rapid hydrogen desorption,economic viability,and effective thermal management in practical applications.Herein,the fundamental theories,recent advances,and practical applications of the nanostructured Mg-based hydrogen storage materials are discussed.The synthetic strategies are classified into four categories:free-standing nano-sized Mg/MgH_(2)through electrochemical/vapor-transport/ultrasonic methods,nanostructured Mg-based composites via mechanical milling methods,construction of core-shell nano-structured Mg-based composites by chemical reduction approaches,and multi-dimensional nano-sized Mg-based heterostructure by nanoconfinement strategy.Through applying these strategies,near room temperature ab/de-sorption(<100℃)with considerable high capacity(>6 wt%)has been achieved in nano Mg/MgH_(2)systems.Some perspectives on the future research and development of nanostructured hydrogen storage materials are also provided.
基金supported by research programs of National Natural Science Foundation of China(52101274,51731002)Natural Science Foundation of Shandong Province(No.ZR2020QE011)Youth Top Talent Foundation of Yantai University(2219008).
文摘MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost characteristics.But some shortcomings are still existed:high operating temperature and poor hydrogen absorption dynamics,which limit its application.Porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres(NZC/Ni@CNT)is prepared by facile filtration and calcination method.Then the different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%)is added to the MgH_(2) by ball milling.Among the three samples with different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%),the MgH_(2)-5 wt%NZC/Ni@CNT composite exhibits the best hydrogen storage performances.After testing,the MgH_(2)-5 wt%NZC/Ni@CNT begins to release hydrogen at around 110℃ and hydrogen absorption capacity reaches 2.34 wt%H_(2) at 80℃ within 60 min.Moreover,the composite can release about 5.36 wt%H_(2) at 300℃.In addition,hydrogen absorption and desorption activation energies of the MgH_(2)-5 wt%NZC/Ni@CNT composite are reduced to 37.28 and 84.22 KJ/mol H_(2),respectively.The in situ generated Mg_(2)NiH_(4)/Mg_(2)Ni can serve as a"hydrogen pump"that plays the main role in providing more activation sites and hydrogen diffusion channels which promotes H_(2) dissociation during hydrogen absorption process.In addition,the evenly dispersed Zn and MgZn2 in Mg and MgH_(2) could provide sites for Mg/MgH_(2) nucleation and hydrogen diffusion channel.This attempt clearly proved that the bimetallic carbide Ni_(3)ZnC_(0.7) is a effective additive for the hydrogen storage performances modification of MgH_(2),and the facile synthesis of the Ni_(3)ZnC_(0.7)/Ni@CNT can provide directions of better designing high performance carbide catalysts for improving MgH_(2).
文摘The effect of heat-treatment process on the properties of Mm0.8Mg0.2(NiCoAlMn)3.5 hydrogen storage alloy was discussed . The electrochemical properties such as cycling stability, activation property, and the plateau voltage of the alloy which was heat-treated in various temperatures and times had different changes during the cycle process, the optimum heat-treatment conditions of this alloy were determined by this work.
文摘A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1). after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).
文摘The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x <0.2 for Ml could improve its discharge capacity, but Ca substitution with x >0.2 could decrease the capacity. It was also found that Ca substitution deteriorates the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. In order to improve these properties of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 alloy electrode, the alloy was treated in 6 mol/L KOH+0.02 mol/L KBH 4 solution. The results showed that the surface treatment improves the electrochemical performances such as the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. :The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x <0.2 for Ml could improve its discharge capacity, but Ca substitution with x >0.2 could decrease the capacity. It was also found that Ca substitution deteriorates the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. In order to improve these properties of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 alloy electrode, the alloy was treated in 6 mol/L KOH+0.02 mol/L KBH 4 solution. The results showed that the surface treatment improves the electrochemical performances such as the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode.
基金Project supported by the Competitiveness Enhancement Program of National Research Tomsk Polytechnic University(Grant No.VIU-OEF-66/2019)
文摘Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/desorption rate and excessive hydrogen absorption/desorption temperature limit the application of Mg-based hydrogen storage materials.The present paper reviews the advances in the research of Mg-based hydrogen storage film in recent years, including the advantage of the film, the function theory of fabricating method and its functional theory, and the influencing factors in the technological process. The research status worldwide is introduced in detail. By comparing pure Mg, Pd-caped Mg, nonpalladium capped Mg, and Mg alloy hydrogen storage films, an ideal tendency for producing Mg-based film is pointed out,for example, looking for a cheap metal element to replace the high-priced Pd, compositing Mg film with other hydrogen storage alloy of catalytic elements, and so on.
基金financially supported by the National Natural Science Foundations of China(51761032 and 51871125)the Natural Science Foundations of Inner Mongolia,China(No.2019BS05005)the Scientific Research Staring Foundation of Taiyuan University of Science and Technology(20202040)
文摘The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction.The catalysis of Co@C composites on the hydrogen storage behavior of Mg_(90)Ce_(5)Y_(5)alloy was investigated in detail by XRD,SEM,TEM,PCI,and DSC method.Because of the synergistic catalytic function of C and Co in C@Co nanocomposites,the Mg_(90)Ce_(5)Y_(5)alloy with 10 wt.%C@Co shows the excellent hydrogen absorption and desorption performances.Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300℃.Meanwhile,the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol^(-1)H_(2)after the addition of the C@Co composites.This positive effect attributes to the C layer with the high defect density and the Co nanoparticles,which reduces the energy barriers for the nucleation of Mg/MgH_(2)phase and the recombination of hydrogen molecule.Besides,the C@Co composites also improve the activation property of the Mg_(90)Ce_(5)Y_(5)alloy which was folly activated in the first cycle.Moreover,the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased.Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy,these differences are so small that the improvement on thermodynamics can hardly be seen.
文摘The rapid development of electric vehicles demands the development of high performance nickel metal hydride battery that is able to endure high temperature. The discharge properties of Ti 0.7 Zr 0.5 V 0.2 Mn 1.8- x Ni x ( x =0.4, 0.8, 1.1, 1.4, 1.7)hydrogen storage alloys was investigated and its phase composition was analyzed using X ray diffraction. The results show that the cycling life was improved as the content of nickel increases. When x =0.4, 0.8, 1.1 and 1.4, the main phase is MgZn 2 type C14 Laves phase and the second one is cubic TiNi phase. When x =1.7, the Laves phase structure disappears. EDAS analysis shows that the increase of nickel content is effective in suppressing the dissolution of vanadium component in alloys. [
基金The work is subsidized by the Special Funds for Major state Basic Research Projects and Project 59781001 of the National Natural Science Foundation of China.
文摘Mg-based hydrogen storage alloys are considered as a promising candidate for hydrogen system because of its lightweight, high storage capacity, low price and rich mineral resources. In detail, we reviewed the preparation and properties of Mg-Ni-based hydrogen storage alloys. All kinds of attempts have been done to improve the hydriding and dehydriding behaviors. It is found that the partial substitution of foreign elements can decrease the hydrogen absorption temperature, especially the substitution of a more electronegative element, such as AI and Mn. Mechanical alloying (MA) and mechanical grinding (MG) are the most effective methods to improve the hydriding/dehydriding kinetics and electrochemical capacity, and decrease the desorption temperature. but the corrosion resistance is so poor that the 80% of maximum capacity is lost within ten cycles. Microencapsulation is a useful measurement for improving the corrosion resistance and electrocatalytic activity. fn order to improve the properties of the alloys for practical application, the alloys should have a large number of defects, which give activated sites, subsequently, MA, MG and electroless plating should be used to improve the hydriding/dehydriding kinetics and protect the surface of alloys, respectively. The new composite Mg-based alloys give a new way for the hydrogen storage material to practical application. Furthermore we put forward several problems which will be discussed in future.
文摘A series of multi-component M1-based hydrogen storage alloys witha cobalt atomic ratio of 0.40-0.75 were prepared. The electrochemicalproperties under different charge-discharge conditions and PCTcharaceristics measured by electrochemical method were investigated.The addition of other alloying elements for partial substitution ofCo low- ers the hydrogen equilibrium pressure and discharge capacity,but improves the cycling stability and makes the alloys keep nearlythe same rate discharge capability and high-temperature dischargecapability as those of the compared alloy. The reasons werediscussed.
文摘Mg-based hydrogen storage nanocomposites added with carbon nanotubes(CNTs) were prepared by mechanical milling under the atmosphere of hydrogen. The results show that because of their own excellent heat conductivity and good hydrogen storage ability, the carbon nanotubes improve the mass transfer and heat transfer properties of the Mg-based nanocomponents, thus enhancing the kinetic property of hydrogen absorption and desorption of the hydrogen storage nanocomposites, and raising the hydrogen storage capacity. Due to the addition of the carbon nanotubes, the milling stress in the process of preparing the Mg-based nanocomposites is reduced, the components can be closely bonded easily, and the additives can play better catalytic roles.
文摘The kinetics equation of the Mg-based hydrogen storage alloys (Mg-Ni-MO) was established by the shell and shrinking core model. The total coefficients of the kinetics equation of the hydrogen absorption and desorption process with shell diffusion as the controlling step were determined by semi-empirical and semi-theoretical methods, and the apparent activation energy of the hydrogen absorption process was obtained. The calculation results can well accord with the experimental data, and can well forecast the hydrogen storage capacity and absorption rate at different times. By using the kinetics equation, the effects of temperature and pressure on the hydrogen storage process can also be well understood. The kinetics equation is helpful for the design of the hydrogen storage container.
文摘The effect of the hot-charging treatment on the performance of AB(2) and AB(5) hydrogen storage alloy electrodes was investigated. The result showed that the treatment can markedly improve the voltage plateau ratio (VPR), the high rate discharge ability (HRDA), the diffusion coefficient of hydrogen DH and the discharge capacity of the AB2 hydrogen storage alloy electrode. The SEM analysis showed that the hot-charging treatment brings about a Ni-rich surface due to the dissolution of Zr oxides. It is also very helpful for the improvement of the kinetic properties of AB2 hydrogen storage alloy electrode because the microcracking of the surface results in fresh surface. This can be the basic modification treatment for NiMH battery used in electric vehicles (EVs) in the future. But for AB(5) type alloys, the treatment has the disadvantage of impairing the comprehensive electrochemical properties, because the surface of the alloy may be corroded during the treatment. The mechanism of the surface modification of the electrode is also proposed.
文摘Ti0.5Al0.25Ni0.25 alloy prepared by vacuum induction melting was studied.The phase composition was analyzed with X-ray technique and EDS analysis,and its electrochemical properties were investigated at various temperatures.Electrochemical reaction kinetic parameters were also studied with proper electrochemical techniques.The influence of the secondary corrosion reaction on the anodic linear polarization measurement was also analyzed by theoretical simulation.The results show that,proper ball-milling with nickel powders is beneficial to electrochemical performance.The theoretical simulation proves that,the existence of the side reaction can disturb the measurement of electrochemical reaction kinetic parameters.
文摘The impedance diagram of hdrogen storage electrodes(AH electrodes )displayed twosemicircles.Thelow frequency one is affected by cycle number and composition of MH electrodes.
文摘The microstructures and electrode properties of Cr or Co-doped V2.1 TiNi0.5 Hf0.05M 0.113 (M=Cr, Co) hydrogen storage alloys were investigated. It is found that all alloys consist of a main phase of V-based solid solution with b.c.c. structure and a secondary phase of C14-type Laves phase with a three-dimensional network structure. After the doping of Cr or Co into V 2.1TiNi 0.5Hf 0.05, the abundance and unit cell volume of the main phase decrease, and those of the secondary phase increase. The electrochemical measurements show that the discharge capacities of Cr-doped V2.1 TiNi0.5 Hf0.05Cr 0.113 alloy and Co-doped V2.1 TiNi0.5 Hf0.05Co 0.113 alloy are less than that of V2.1 TiNi0.5 Hf0.05 alloy, but their cycle stability and high-rate dischargeability are improved markedly. The results show that Cr or Co doping into V2.1 TiNi0.5 Hf0.05 alloy is significantly beneficial for the cycling stability.
基金Project(50171021) supported by the National Natural Science Foundation of China
文摘The influence of the addition of Cu(OH)2 to 6 mol/L KOH alkaline electrolyte on the electrochemical properties of La2Mg0.9Al0.1Ni7.5Co1.5 hydrogen storage alloy electrode was investigated by electron probe X-ray microanalysis(EPMA),X-ray diffraction(XRD) and electrochemical measurements. EPMA micrographs and XRD patterns show that the surface of the hydride electrode is plated by metal copper film. The thickness and compactness of Cu film increase with the increment of charge-discharge cycle number. The copper film of the hydride electrode surface can keep the hydrogen storage alloy particle in the electrode interior from oxidizing availably. The addition of Cu(OH)2 to alkaline electrolyte lowers the activation property and the high rate dischargeability of the La2Mg0.9Al0.1Ni7.5Co1.5 hydride electrode,but has no negative effect on the maximum discharge capacity of the hydride electrode. Moreover,it is effective to improve the cyclic stability of the hydride electrode utilizing electrodeposit Cu film on the La2Mg0.9Al0.1Ni7.5Co1.5 hydride electrodes surface.
基金supported by Natural Science Foundation of Shaanxi Province,China(2017JM5079)The 111 project(No.B08040)is also acknowledged.
文摘Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding cycling kinetics and thermodynamic stability of the experimental alloys have been investigated in detail.The results show that the Mg-Ni-La alloys exhibit improved hydrogen storage cycling properties and can remain storage hydrogen above 5.5 wt%after 200 cycles.With the increase of cycling numbers,the dehydrogenation rates of the experimental samples increase firstly and then gradually decrease,and eventually maintain relative stable state.Microstructure observation reveals that powders sintering and hydrogen decrepitation both exist during hydrogen absorption/desorption cycles due to repeated volume expansion and contraction.Meanwhile,the in-situ formed LaH_(x)(x=2,3)and Mg_(2)Ni nanocrystallines stabilize the microstructures of the particles and hinder the powders sintering.After 200 cycles,the average particle size of the experimental samples decreases and the specific surface area apparently increases,which leads to the decomposition temperatures of MgH_(2)and Mg_(2)NiH_(4)slightly shift to lower temperatures.Moreover,Mg_(2)Ni and LaH_(x)(x=2,3)have been proven to be stable catalysts during long-term cycling,which can still uniformly distribute within the powders after 200 cycles.