The effect of thickness (1 similar to 10 mm) of the ingots on the electrochemical properties of as-cast and annealed strip cast LPCNi3.55Co0.75Mn0.4Al0.3 hydrogen storage alloys was investigated. It is found that the ...The effect of thickness (1 similar to 10 mm) of the ingots on the electrochemical properties of as-cast and annealed strip cast LPCNi3.55Co0.75Mn0.4Al0.3 hydrogen storage alloys was investigated. It is found that the 0.2 C discharge capacity of as-cast LPCNi3.55Co0.75Mn0.4Al0.3 alloy increases with the increase of the thickness of the ingots. As-east alloy with the thickness of 10 mm shows better activation property, higher 1C discharge capacity and better cyclic stability than others. It is mainly contributed to its larger unit cell volume and less internal stress. Annealed LPCNi3.55Co0.75Mn0.4Al0.3 alloy with the thickness of 3 mm shows much better comprehensive electrochemical properties than as-east one; The cyclic. stability of the alloy with the thickness of 6 mm and the activation properties of the alloys with the thickness of 3 similar to 6 mm are improved after annealing. It is mainly owing to the great release of internal stress and the decrease of the segregation of Mn in the alloys.展开更多
LPCNi 3.55 Co 0.75 Mn 0.4 Al 0.3 hydrogen storage alloy was investigated, and the effects of thickness of its strip casting ingots(as cast) on the electrochemical performances were discussed. It was ...LPCNi 3.55 Co 0.75 Mn 0.4 Al 0.3 hydrogen storage alloy was investigated, and the effects of thickness of its strip casting ingots(as cast) on the electrochemical performances were discussed. It was found that the 0.2 C discharge capacity increased with the increase of the thickness (from 1 mm to 10 mm) of the ingots, mainly due to the enlargement of the unit cell volume; Among the thickness of the ingots in our study, 10 mm sample showed a better activation property; LPCNi 3.55 Co 0.75 Mn 0.4 Al 0.3 alloy with 10mm showed higher comprehensive properties than those with other thickness under 1C rate.展开更多
In order to reduce the cost of LaNi5 based hydrogen storage alloys, effect of substitution of Mn for Ni on structural and electrochemical properties of LaNi4-xFeMnx (x=0-0.8) hydrogen storage alloys was studied system...In order to reduce the cost of LaNi5 based hydrogen storage alloys, effect of substitution of Mn for Ni on structural and electrochemical properties of LaNi4-xFeMnx (x=0-0.8) hydrogen storage alloys was studied systematically. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that LaNi5 and La2Ni7 phases were invariably present in all alloy samples, and when x >= 0.4, (Fe, Ni) phase was observed. Electrochemical studies revealed that the discharge capacity reached a maximum value of 306.4 mAh/g when x=0.2 and the cycling stability decreased with the increase of x. With the increase of Mn content, hydrogen diffusion coefficient decreased, whereas high rate discharge-ability (HRD) and exchange current density first increased slowly when x <= 0.2 and then decreased markedly when x=0.8, indicating that electrochemical reaction on the surface of alloy electrodes had strong influence on kinetic property.展开更多
The electronic structures of LaNi5 hydrogen storage alloys and its micro-hydrogenated compounds with two hydrogen atoms in the center of two octahedral interstices and two tetrahedral interstices, were investigated by...The electronic structures of LaNi5 hydrogen storage alloys and its micro-hydrogenated compounds with two hydrogen atoms in the center of two octahedral interstices and two tetrahedral interstices, were investigated by the first principles discrete variational method （DVM）. The results of density of states and the difference of charge distribution clearly show that the s electrons of H mainly interact with the s electrons of hydride-non-forming element Ni, despite there being a larger affinity of La for hydrogen than that of Ni in pure metal-hydrogen system. From the cohesive energy of systems, we also found two systems have almost same stability with occupation of H atoms.展开更多
The microstructure ofthe Mg/MmNi5-x (CoAlMn )x composite hydrogen storage material preparedby the method of mechanical alloyingwas characterized by X-ray diffraction, SEM and particle size distribution analysis. By me...The microstructure ofthe Mg/MmNi5-x (CoAlMn )x composite hydrogen storage material preparedby the method of mechanical alloyingwas characterized by X-ray diffraction, SEM and particle size distribution analysis. By measuring PCTcurves, the hydrogen absorption properties of the composite was evaluated.The results show that nanocrystallinecomposite structure can be obtainedunder adequate ball milling condition. The reactive activation and hydrogen absorption capacity are improved compared with the sole MmNi5-x(CoAlMn)x alloy. The effect ofmagnesium on the microstructure andhydrogen absorption properties of thecomposite were also evaluated.展开更多
La（1-x）MgxNi（1.75）Co（2.05）（x=0.07, 0.08, 0.10, 0.13, 0.15） alloys were prepared by high-frequency inductive method, and then their structure and electrochemical properties were investigated systematically. The...La（1-x）MgxNi（1.75）Co（2.05）（x=0.07, 0.08, 0.10, 0.13, 0.15） alloys were prepared by high-frequency inductive method, and then their structure and electrochemical properties were investigated systematically. The XRD analysis revealed that the alloys consisted of LaNi5 phase and La4MgNi（19）（Ce5Co（19） ＋ Pr5Co（19）） phase, and the introduction of Mg could promote the formation of La4MgNi（19） phase. The observation of microstructure showed that all the alloys processed dendritic structure, which was refined with the increase of x value. The electrochemical measurements showed that all the alloys could be activated within 2 cycles, and with increasing x, the maximum discharge capacity obviously increased from 254.00 m Ah/g（x=0.07） to 351.51 mAh/g（x=0.15）, but the cycling stability（S（80）） decreased somehow from 78.4% to 73.9%. Meanwhile, the appropriate addition of Mg could improve the high-rate discharge capacity（HRD） of the alloy electrodes, which was mainly controlled by the electrochemical reaction rate on the surface of the alloys.展开更多
The microstructttres and electrochemical properties of LaNi3.8-xAlx （x=0.0, 0.1, 0.2, 0.3 and 0.4） alloys were studied sys- tematically. The microstructures were identified by X-ray diffraction （XRD） and scanning ...The microstructttres and electrochemical properties of LaNi3.8-xAlx （x=0.0, 0.1, 0.2, 0.3 and 0.4） alloys were studied sys- tematically. The microstructures were identified by X-ray diffraction （XRD） and scanning electronic microscopy （SEM）. The main phases were not changed with the substitution of Ni by A1, but minor phases appeared when x=0.4. With A1 content increasing, the cell volume increased and the hydrogen storage capacity increased first and then decreased, and the maximum discharge capacity increased fi：om 209.4 mAh/g （x=0.0） to 285.3 mAh/g （x=0.3） and then decreased to 241.3 mAh/g （x=0.4）. Meanwhile, the exchange current density （10） increased and the diffusion coefficient （D） decreased with the addition of Al.展开更多
Magnesium(Mg)-based alloys have already been widely studied as the hydrogen storage materials because of their high reversible hydrogen storage capacity,low cost,light weight,etc.However,the poor de/hydrogenation kine...Magnesium(Mg)-based alloys have already been widely studied as the hydrogen storage materials because of their high reversible hydrogen storage capacity,low cost,light weight,etc.However,the poor de/hydrogenation kinetic properties dramatically hinder the practical applications.In this work,the MgH_(2)-ANi_(5)(A=Ce,Nd,Pr,Sm,and Y) composites were prepared by a high-energy ball milling method.which can effectively refine the particle size thus improving the kinetic properties.Experimental results reveal that the MgH_(2)-ANi_(5) composites mainly consist of Mg_(2)NiH_(4),MgH_(2) and rare earth(RE) hydride,which will be dehydrogenated to form Mg_(2)Ni,Mg and stable RE hydride reversibly.Accordingly,the asmilled MgH_(2)-ANi_(5)(A=Ce,Nd,Pr,Sm,and Y) composites with various A-elements can respectively contribute to a reversible hydrogen storage capacity of 6.16 wt%,5.7 wt%,6.21 wt%,6.38 wt%,and 6.5 wt%at a temperature of 300℃,and show much better kinetic properties in comparison to the pure MgH_(2) without any additive.In-situ formed Mg_(2) Ni and stable RE hydride(such as CeH_(2.73) and YH_(2)) might act as effective catalysts to significantly improve the hydrogen storage properties of MgH_(2).The present work provides a guideline on improving the kinetic properties of the Mg-based hydrogen storage alloys.展开更多
文摘The effect of thickness (1 similar to 10 mm) of the ingots on the electrochemical properties of as-cast and annealed strip cast LPCNi3.55Co0.75Mn0.4Al0.3 hydrogen storage alloys was investigated. It is found that the 0.2 C discharge capacity of as-cast LPCNi3.55Co0.75Mn0.4Al0.3 alloy increases with the increase of the thickness of the ingots. As-east alloy with the thickness of 10 mm shows better activation property, higher 1C discharge capacity and better cyclic stability than others. It is mainly contributed to its larger unit cell volume and less internal stress. Annealed LPCNi3.55Co0.75Mn0.4Al0.3 alloy with the thickness of 3 mm shows much better comprehensive electrochemical properties than as-east one; The cyclic. stability of the alloy with the thickness of 6 mm and the activation properties of the alloys with the thickness of 3 similar to 6 mm are improved after annealing. It is mainly owing to the great release of internal stress and the decrease of the segregation of Mn in the alloys.
文摘LPCNi 3.55 Co 0.75 Mn 0.4 Al 0.3 hydrogen storage alloy was investigated, and the effects of thickness of its strip casting ingots(as cast) on the electrochemical performances were discussed. It was found that the 0.2 C discharge capacity increased with the increase of the thickness (from 1 mm to 10 mm) of the ingots, mainly due to the enlargement of the unit cell volume; Among the thickness of the ingots in our study, 10 mm sample showed a better activation property; LPCNi 3.55 Co 0.75 Mn 0.4 Al 0.3 alloy with 10mm showed higher comprehensive properties than those with other thickness under 1C rate.
基金Project supported by the National Nature Science Foundation of China (NSFC50571072)GD-MOE Coordination Project of Industry Academic and Research (2008B090500274)
文摘In order to reduce the cost of LaNi5 based hydrogen storage alloys, effect of substitution of Mn for Ni on structural and electrochemical properties of LaNi4-xFeMnx (x=0-0.8) hydrogen storage alloys was studied systematically. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that LaNi5 and La2Ni7 phases were invariably present in all alloy samples, and when x >= 0.4, (Fe, Ni) phase was observed. Electrochemical studies revealed that the discharge capacity reached a maximum value of 306.4 mAh/g when x=0.2 and the cycling stability decreased with the increase of x. With the increase of Mn content, hydrogen diffusion coefficient decreased, whereas high rate discharge-ability (HRD) and exchange current density first increased slowly when x <= 0.2 and then decreased markedly when x=0.8, indicating that electrochemical reaction on the surface of alloy electrodes had strong influence on kinetic property.
基金Project supported bythe National Natural Science Foundations of China (50131040 and 50071050)
文摘The electronic structures of LaNi5 hydrogen storage alloys and its micro-hydrogenated compounds with two hydrogen atoms in the center of two octahedral interstices and two tetrahedral interstices, were investigated by the first principles discrete variational method （DVM）. The results of density of states and the difference of charge distribution clearly show that the s electrons of H mainly interact with the s electrons of hydride-non-forming element Ni, despite there being a larger affinity of La for hydrogen than that of Ni in pure metal-hydrogen system. From the cohesive energy of systems, we also found two systems have almost same stability with occupation of H atoms.
文摘The microstructure ofthe Mg/MmNi5-x (CoAlMn )x composite hydrogen storage material preparedby the method of mechanical alloyingwas characterized by X-ray diffraction, SEM and particle size distribution analysis. By measuring PCTcurves, the hydrogen absorption properties of the composite was evaluated.The results show that nanocrystallinecomposite structure can be obtainedunder adequate ball milling condition. The reactive activation and hydrogen absorption capacity are improved compared with the sole MmNi5-x(CoAlMn)x alloy. The effect ofmagnesium on the microstructure andhydrogen absorption properties of thecomposite were also evaluated.
基金Project supported by the National Natural Science Foundation of China(50901036)the Graduate Science and Technology Innovation Project of Jiangsu University of Science and Technology(YCX15S-18)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘La（1-x）MgxNi（1.75）Co（2.05）（x=0.07, 0.08, 0.10, 0.13, 0.15） alloys were prepared by high-frequency inductive method, and then their structure and electrochemical properties were investigated systematically. The XRD analysis revealed that the alloys consisted of LaNi5 phase and La4MgNi（19）（Ce5Co（19） ＋ Pr5Co（19）） phase, and the introduction of Mg could promote the formation of La4MgNi（19） phase. The observation of microstructure showed that all the alloys processed dendritic structure, which was refined with the increase of x value. The electrochemical measurements showed that all the alloys could be activated within 2 cycles, and with increasing x, the maximum discharge capacity obviously increased from 254.00 m Ah/g（x=0.07） to 351.51 mAh/g（x=0.15）, but the cycling stability（S（80）） decreased somehow from 78.4% to 73.9%. Meanwhile, the appropriate addition of Mg could improve the high-rate discharge capacity（HRD） of the alloy electrodes, which was mainly controlled by the electrochemical reaction rate on the surface of the alloys.
文摘The microstructttres and electrochemical properties of LaNi3.8-xAlx （x=0.0, 0.1, 0.2, 0.3 and 0.4） alloys were studied sys- tematically. The microstructures were identified by X-ray diffraction （XRD） and scanning electronic microscopy （SEM）. The main phases were not changed with the substitution of Ni by A1, but minor phases appeared when x=0.4. With A1 content increasing, the cell volume increased and the hydrogen storage capacity increased first and then decreased, and the maximum discharge capacity increased fi：om 209.4 mAh/g （x=0.0） to 285.3 mAh/g （x=0.3） and then decreased to 241.3 mAh/g （x=0.4）. Meanwhile, the exchange current density （10） increased and the diffusion coefficient （D） decreased with the addition of Al.
基金the National Key R&D Program of China(2018YFB1502101,2019YFB1505101)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(NSFC51621001)National Natural Science Foundation of China(51771075,51701171)。
文摘Magnesium(Mg)-based alloys have already been widely studied as the hydrogen storage materials because of their high reversible hydrogen storage capacity,low cost,light weight,etc.However,the poor de/hydrogenation kinetic properties dramatically hinder the practical applications.In this work,the MgH_(2)-ANi_(5)(A=Ce,Nd,Pr,Sm,and Y) composites were prepared by a high-energy ball milling method.which can effectively refine the particle size thus improving the kinetic properties.Experimental results reveal that the MgH_(2)-ANi_(5) composites mainly consist of Mg_(2)NiH_(4),MgH_(2) and rare earth(RE) hydride,which will be dehydrogenated to form Mg_(2)Ni,Mg and stable RE hydride reversibly.Accordingly,the asmilled MgH_(2)-ANi_(5)(A=Ce,Nd,Pr,Sm,and Y) composites with various A-elements can respectively contribute to a reversible hydrogen storage capacity of 6.16 wt%,5.7 wt%,6.21 wt%,6.38 wt%,and 6.5 wt%at a temperature of 300℃,and show much better kinetic properties in comparison to the pure MgH_(2) without any additive.In-situ formed Mg_(2) Ni and stable RE hydride(such as CeH_(2.73) and YH_(2)) might act as effective catalysts to significantly improve the hydrogen storage properties of MgH_(2).The present work provides a guideline on improving the kinetic properties of the Mg-based hydrogen storage alloys.
