The effects of low-Co AB_5 type hydrogen storage alloys prepared by quenchingand annealing on the performances of MH-Ni batteries were investigated, and the characteristics ofthe low-Co AB_5 type hydrogen storage allo...The effects of low-Co AB_5 type hydrogen storage alloys prepared by quenchingand annealing on the performances of MH-Ni batteries were investigated, and the characteristics ofthe low-Co AB_5 type hydrogen storage alloys were compared with those of the high-Co AB_5 typehydrogen storage alloy as well. The results showed that the faster the cooling of the low-Cohydrogen storage alloy is, the better homogeneity of the chemical composition for the alloy and thelonger cycle life of the battery are, but the electrochemical discharge capacity and high-ratedischarge ability are reduced. The high-rate discharge ability and charge retention of MH-Nibatteries for the conventional as-cast annealed low-Co hydrogen storage alloy were superior to thosefor the rapidly quenched low-Co hydrogen storage alloy and the high-Co hydrogen storage alloy, buta little inferior in the cycle life.展开更多
AB5 hydrogen storage alloys La0.54Ce0.28Pr0.18Ni4-xCo0.6Mn0.35Alx(x=0.1,0.2,0.3) were prepared by arc melting method under an Ar atmosphere. The results show that the contents of Ni and Al have obvious influences on t...AB5 hydrogen storage alloys La0.54Ce0.28Pr0.18Ni4-xCo0.6Mn0.35Alx(x=0.1,0.2,0.3) were prepared by arc melting method under an Ar atmosphere. The results show that the contents of Ni and Al have obvious influences on the microstructure and electrochemical properties of the alloys. Both the lattice parameters and the cell volumes decrease with decreasing x value. Moreover,the discharge capacity at different temperatures,the high rate discharge property,and the cycling life of the alloy electrode are also in close relationship with the x value. When x value increases from 0.1 to 0.3,the discharge capacities with a discharge current density of 60 mA/g slightly decreases at 25 ℃,but evidently deteriorates at -40 ℃,the high-rate property gravely decreases,and the cycle life of the alloy electrode is improved in some extent. Therefore,it is meaningful to control Al content for the AB5 hydrogen storage alloys used in Ni/MH batteries.展开更多
Rare earth compositions, La, Ce and Pr in Mm(NiCoMnAl)(5) hydrogen storage alloy, were arranged by uniform design method. The discharge performances and kinetics parameters including capacity, exchange current density...Rare earth compositions, La, Ce and Pr in Mm(NiCoMnAl)(5) hydrogen storage alloy, were arranged by uniform design method. The discharge performances and kinetics parameters including capacity, exchange current density, symmetry factor and hydrogen diffusion coefficient of the alloy at -40degreesC, were tested in standard tri-electrode cell. And linear regression method was used to analyze the effect of rare earth compositions on the performances of hydrogen storage alloys. The results show that the capacities of the alloys are positively correlative to the square of Ce content at -40degreesC and under both 0.4 and 0.2C rate. The kinetics parameters and hydrogen diffusion coefficient indicate that the low-temperature performances of the alloys are mainly controlled by hydrogen diffusion process, and the surface electrochemical reaction affects the low-temperature performances to a certain extent. The low-temperature discharge capacities of the battery were also tested. The results show excellent low-temperature performances. The battery delivers 69.6% of its room-temperature capacity at -40degreesC and 0.2C rate, 77.7% at -40degreesC and 0.4C rate, 59.1% at -45degreesC and 0.2C rate.展开更多
The influences of deeply overdischarge on the negative electrode alloy of Ni/MH battery were studied. After overdischarge, La(OH) 3 and Al(OH) 3 are found to form in the negative electrode through XRD analysis. The ...The influences of deeply overdischarge on the negative electrode alloy of Ni/MH battery were studied. After overdischarge, La(OH) 3 and Al(OH) 3 are found to form in the negative electrode through XRD analysis. The hydrogen storage alloy powder from spent Ni/MH batteries was recovered by chemical and melting method according to degradation mechanism. The structure of recovered alloy was measured by XRD. The experimental results demonstrate that the alloy structure is CaCu 5 type. The constant current charge/discharge test was carried out to the original alloy and the recovered alloy. It is found that their discharge capacities are almost the same, but the discharge potential of the recovered alloy is higher than that of the original alloy. The results of cyclic lifetime test demonstrate that the capacity degradation of the recovered alloy is slower than that of the original one.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 development trend and promising application prospects of high-power MH-Ni battery were reviewed by studying and comparing the current high-power batteries research area.High-power MH-Ni batiery has good performlif...The development trend and promising application prospects of high-power MH-Ni battery were reviewed by studying and comparing the current high-power batteries research area.High-power MH-Ni batiery has good performlife with 500 ～ 1000 times, abundant material resource, especially abundant rare earth resource in China, high-rate discharging, rapid charging, good safety as well as no pollution, etc., which is regarded as the most promising storage battery for electric vehicles.The performance of high power MH-Ni battery can be brought into play fully and ensure electric vehicles performance if it is equipped with appropriate chargers, controlling system and electric motors.Facing opportunities and challenges, MH-Ni battery has promising application prospects on hybrid electric automobile, electric bicycle and a variety of small sized electric vehicles by improving its technology constantly and developing market actively.展开更多
The electrochemical characteristics and crystal structure of metal hydride electrode of AB_(3.5)-type alloy was studied. The electrochemical properties of the metal hydride electrode were investigated at room temperat...The electrochemical characteristics and crystal structure of metal hydride electrode of AB_(3.5)-type alloy was studied. The electrochemical properties of the metal hydride electrode were investigated at room temperature and -30 ℃. The partial substitution of Ni by Al element causes an expansion of the lattice cell and increases the specific capacity and rate discharge ability of the alloy.展开更多
The Co(Ⅲ)-coated spherical nickel hydroxide powder is optimum as positive electrode of high power Ni-MH battery because of its excellent property. But the performances at high temperature(above 50 ℃) is still not sa...The Co(Ⅲ)-coated spherical nickel hydroxide powder is optimum as positive electrode of high power Ni-MH battery because of its excellent property. But the performances at high temperature(above 50 ℃) is still not satisfied. In the present paper,the effect of element erbium,used as additive by different methods to prepare positive electrode,on the high temperature performances of the Ni-MH batteries is studied. It is found that the charge acceptance ability of the spherical Ni(OH)2 electrode with element erbium as additive is improved. The discharge capacities of Ni(OH)2 coated with 1%(atomic fraction) Er(OH)3 and mechanically added with 1%(atomic fraction) Er2O3 at 1C are 12.6% and 11.7%,respectively,higher than those of the samples without erbium at 70 ℃.展开更多
文摘The effects of low-Co AB_5 type hydrogen storage alloys prepared by quenchingand annealing on the performances of MH-Ni batteries were investigated, and the characteristics ofthe low-Co AB_5 type hydrogen storage alloys were compared with those of the high-Co AB_5 typehydrogen storage alloy as well. The results showed that the faster the cooling of the low-Cohydrogen storage alloy is, the better homogeneity of the chemical composition for the alloy and thelonger cycle life of the battery are, but the electrochemical discharge capacity and high-ratedischarge ability are reduced. The high-rate discharge ability and charge retention of MH-Nibatteries for the conventional as-cast annealed low-Co hydrogen storage alloy were superior to thosefor the rapidly quenched low-Co hydrogen storage alloy and the high-Co hydrogen storage alloy, buta little inferior in the cycle life.
基金Project (2001AA322050) supported by the National Hi-tech Research and Development Program of China
文摘AB5 hydrogen storage alloys La0.54Ce0.28Pr0.18Ni4-xCo0.6Mn0.35Alx(x=0.1,0.2,0.3) were prepared by arc melting method under an Ar atmosphere. The results show that the contents of Ni and Al have obvious influences on the microstructure and electrochemical properties of the alloys. Both the lattice parameters and the cell volumes decrease with decreasing x value. Moreover,the discharge capacity at different temperatures,the high rate discharge property,and the cycling life of the alloy electrode are also in close relationship with the x value. When x value increases from 0.1 to 0.3,the discharge capacities with a discharge current density of 60 mA/g slightly decreases at 25 ℃,but evidently deteriorates at -40 ℃,the high-rate property gravely decreases,and the cycle life of the alloy electrode is improved in some extent. Therefore,it is meaningful to control Al content for the AB5 hydrogen storage alloys used in Ni/MH batteries.
文摘Rare earth compositions, La, Ce and Pr in Mm(NiCoMnAl)(5) hydrogen storage alloy, were arranged by uniform design method. The discharge performances and kinetics parameters including capacity, exchange current density, symmetry factor and hydrogen diffusion coefficient of the alloy at -40degreesC, were tested in standard tri-electrode cell. And linear regression method was used to analyze the effect of rare earth compositions on the performances of hydrogen storage alloys. The results show that the capacities of the alloys are positively correlative to the square of Ce content at -40degreesC and under both 0.4 and 0.2C rate. The kinetics parameters and hydrogen diffusion coefficient indicate that the low-temperature performances of the alloys are mainly controlled by hydrogen diffusion process, and the surface electrochemical reaction affects the low-temperature performances to a certain extent. The low-temperature discharge capacities of the battery were also tested. The results show excellent low-temperature performances. The battery delivers 69.6% of its room-temperature capacity at -40degreesC and 0.2C rate, 77.7% at -40degreesC and 0.4C rate, 59.1% at -45degreesC and 0.2C rate.
文摘The influences of deeply overdischarge on the negative electrode alloy of Ni/MH battery were studied. After overdischarge, La(OH) 3 and Al(OH) 3 are found to form in the negative electrode through XRD analysis. The hydrogen storage alloy powder from spent Ni/MH batteries was recovered by chemical and melting method according to degradation mechanism. The structure of recovered alloy was measured by XRD. The experimental results demonstrate that the alloy structure is CaCu 5 type. The constant current charge/discharge test was carried out to the original alloy and the recovered alloy. It is found that their discharge capacities are almost the same, but the discharge potential of the recovered alloy is higher than that of the original alloy. The results of cyclic lifetime test demonstrate that the capacity degradation of the recovered alloy is slower than that of the original one.
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 development trend and promising application prospects of high-power MH-Ni battery were reviewed by studying and comparing the current high-power batteries research area.High-power MH-Ni batiery has good performlife with 500 ～ 1000 times, abundant material resource, especially abundant rare earth resource in China, high-rate discharging, rapid charging, good safety as well as no pollution, etc., which is regarded as the most promising storage battery for electric vehicles.The performance of high power MH-Ni battery can be brought into play fully and ensure electric vehicles performance if it is equipped with appropriate chargers, controlling system and electric motors.Facing opportunities and challenges, MH-Ni battery has promising application prospects on hybrid electric automobile, electric bicycle and a variety of small sized electric vehicles by improving its technology constantly and developing market actively.
文摘The electrochemical characteristics and crystal structure of metal hydride electrode of AB_(3.5)-type alloy was studied. The electrochemical properties of the metal hydride electrode were investigated at room temperature and -30 ℃. The partial substitution of Ni by Al element causes an expansion of the lattice cell and increases the specific capacity and rate discharge ability of the alloy.
基金Project(2006AA11A151) supported by the National Hi-Tech Research and Development Program of China
文摘The Co(Ⅲ)-coated spherical nickel hydroxide powder is optimum as positive electrode of high power Ni-MH battery because of its excellent property. But the performances at high temperature(above 50 ℃) is still not satisfied. In the present paper,the effect of element erbium,used as additive by different methods to prepare positive electrode,on the high temperature performances of the Ni-MH batteries is studied. It is found that the charge acceptance ability of the spherical Ni(OH)2 electrode with element erbium as additive is improved. The discharge capacities of Ni(OH)2 coated with 1%(atomic fraction) Er(OH)3 and mechanically added with 1%(atomic fraction) Er2O3 at 1C are 12.6% and 11.7%,respectively,higher than those of the samples without erbium at 70 ℃.
