用XRD、SEM、EDS和电化学测试方法研究了退火温度对A_2B_7型La_(0.33)Y_(0.67)Ni_(3.25)Mn_(0.15)Al_(0.1)储氢合金微观组织和电化学性能的影响规律。结果表明,合金铸态组织由2H-Ce_2Ni_7、3R-Gd_2Co_7、CaCu_5和3R-Ce_5Co_(19)型相组成...用XRD、SEM、EDS和电化学测试方法研究了退火温度对A_2B_7型La_(0.33)Y_(0.67)Ni_(3.25)Mn_(0.15)Al_(0.1)储氢合金微观组织和电化学性能的影响规律。结果表明,合金铸态组织由2H-Ce_2Ni_7、3R-Gd_2Co_7、CaCu_5和3R-Ce_5Co_(19)型相组成;随退火温度(850~950℃)升高,Ce_2Ni_7型主相丰度和晶胞体积逐渐增加,至950℃退火后,CaCu_5和Gd_2Co_7型相基本消失,主相Ce_2Ni_7型相丰度和晶胞体积均达到最大值;退火温度≥950℃时,Ce_2Ni_7型和Ce_5Co_(19)型相丰度分别又有所减少和增加。950℃退火合金具有较低的放氢平台压(1.92~8.70 k Pa)和较高的电化学放电容量(371 mAh/g),经100次充放电循环后其容量保持率S100达到89%。退火合金电极的HRD性能均得到不同程度的提高,其中950℃退火合金具有最佳的大电流放电性能(HRD900=83.4%)。氢在合金中的扩散是影响其高倍率放电性能的控制因素。展开更多
The amorphization transformation of Al-Y-Ni system by mechanical alloying was inves- tigated in both thermodynamic and kinetic aspects.The amorphous powder of Al-rich composition Al_(80)Y_(15)Ni_5 was formed after 70 ...The amorphization transformation of Al-Y-Ni system by mechanical alloying was inves- tigated in both thermodynamic and kinetic aspects.The amorphous powder of Al-rich composition Al_(80)Y_(15)Ni_5 was formed after 70 h milling.The process of the amorphiza- tion was monitored by X-ray diffraction.The dependence of the amorphization on the milling intensity was also discussed.The results show that over milling with extra-high intensity has an unfavourable effect on amorphization of the system.展开更多
The Y-Ni alloy is a primary precursor for the preparation of high-performance La-Y-Ni-based hydrogen storage materials.However,it cannot be produced continuously at low cost,which limits the wide popularization and ap...The Y-Ni alloy is a primary precursor for the preparation of high-performance La-Y-Ni-based hydrogen storage materials.However,it cannot be produced continuously at low cost,which limits the wide popularization and application of La-Y-Ni-based materials.In this paper,this problem was solved perfectly using electrochemical reduction of Y_ (2)O_(3)in the LiF-YF_(3)system.It is found that the reversible reduction from Y^(3+)to Y on the W electrode takes only one step,namely a significant soluble-soluble reaction controlled by Y^(3+)diffusion throughout the melt.Four typical signals of square wave voltammetry(SWV)corresponding to different kinds of Y-Ni intermetallic compounds are observed in LiF-YF_(3)and LiF-YF_(3)-Y_ (2)O_(3)melts,and reduction potential can become positive with the addition of Y_ (2)O_(3),probably because of the formation of more complexes in the melts.Homogeneous Y-Ni alloy samples were produced continuously and prepared via galvanostatic electrolysis by using bargain-price raw material(Y_ (2)O_(3))and setting the current density at 10 A/cm^(2)on the nickel electrode,before they were collected into a bottom receiver.A series of analyses including scanning electron microscopy-energy idspersive X-ray spectroscopy(SEM-EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and inductively coupled plasma mass spectrometry(ICP-MS),demonstrate that concentration of yttrium in Y-Ni alloy is adjustable within the wide range of 44 wt%to 72 wt%by fine-tuning the electrolysis temperature(875-1060℃)in the LiF-YF_(3)system to ensure the optimal hydrogen storage performance and economic efficiency of La-Y-Ni-based hydrogen-storage materials.展开更多
文摘用XRD、SEM、EDS和电化学测试方法研究了退火温度对A_2B_7型La_(0.33)Y_(0.67)Ni_(3.25)Mn_(0.15)Al_(0.1)储氢合金微观组织和电化学性能的影响规律。结果表明,合金铸态组织由2H-Ce_2Ni_7、3R-Gd_2Co_7、CaCu_5和3R-Ce_5Co_(19)型相组成;随退火温度(850~950℃)升高,Ce_2Ni_7型主相丰度和晶胞体积逐渐增加,至950℃退火后,CaCu_5和Gd_2Co_7型相基本消失,主相Ce_2Ni_7型相丰度和晶胞体积均达到最大值;退火温度≥950℃时,Ce_2Ni_7型和Ce_5Co_(19)型相丰度分别又有所减少和增加。950℃退火合金具有较低的放氢平台压(1.92~8.70 k Pa)和较高的电化学放电容量(371 mAh/g),经100次充放电循环后其容量保持率S100达到89%。退火合金电极的HRD性能均得到不同程度的提高,其中950℃退火合金具有最佳的大电流放电性能(HRD900=83.4%)。氢在合金中的扩散是影响其高倍率放电性能的控制因素。
文摘The amorphization transformation of Al-Y-Ni system by mechanical alloying was inves- tigated in both thermodynamic and kinetic aspects.The amorphous powder of Al-rich composition Al_(80)Y_(15)Ni_5 was formed after 70 h milling.The process of the amorphiza- tion was monitored by X-ray diffraction.The dependence of the amorphization on the milling intensity was also discussed.The results show that over milling with extra-high intensity has an unfavourable effect on amorphization of the system.
基金Project supported by the State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization(2020Z2132)Ganjiang Innovation Academy,Chinese Academy of Sciences(E055C002)。
文摘The Y-Ni alloy is a primary precursor for the preparation of high-performance La-Y-Ni-based hydrogen storage materials.However,it cannot be produced continuously at low cost,which limits the wide popularization and application of La-Y-Ni-based materials.In this paper,this problem was solved perfectly using electrochemical reduction of Y_ (2)O_(3)in the LiF-YF_(3)system.It is found that the reversible reduction from Y^(3+)to Y on the W electrode takes only one step,namely a significant soluble-soluble reaction controlled by Y^(3+)diffusion throughout the melt.Four typical signals of square wave voltammetry(SWV)corresponding to different kinds of Y-Ni intermetallic compounds are observed in LiF-YF_(3)and LiF-YF_(3)-Y_ (2)O_(3)melts,and reduction potential can become positive with the addition of Y_ (2)O_(3),probably because of the formation of more complexes in the melts.Homogeneous Y-Ni alloy samples were produced continuously and prepared via galvanostatic electrolysis by using bargain-price raw material(Y_ (2)O_(3))and setting the current density at 10 A/cm^(2)on the nickel electrode,before they were collected into a bottom receiver.A series of analyses including scanning electron microscopy-energy idspersive X-ray spectroscopy(SEM-EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and inductively coupled plasma mass spectrometry(ICP-MS),demonstrate that concentration of yttrium in Y-Ni alloy is adjustable within the wide range of 44 wt%to 72 wt%by fine-tuning the electrolysis temperature(875-1060℃)in the LiF-YF_(3)system to ensure the optimal hydrogen storage performance and economic efficiency of La-Y-Ni-based hydrogen-storage materials.
