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研究适用于电动车用大型动力MH/Ni电池,是电池工作者的研究重点之一.本文采用机械合金化方法制备MgNi合金,用作MH/Ni电池金属氢化物电极,研究了温度对其电化学性能的影响,探索MgNi合金作为MH/Ni动力电池负极材料的可能性.TEM测试结果表明机械合金化方法制备的MgNi合金为纳米结构,粒径在10nm以下.在30℃和70℃条件下测定金属氢化物电极的电化学性能,结果表明在70℃时电化学容量173mA·h·g-1,约为在30℃放电容量110mA·h·g-1的1.6倍,大电流充放电及高倍率放电性能高温优于低温. 相似文献
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AB5-AB2复合合金电极的微观结构和活化性能 总被引:4,自引:0,他引:4
根据AB5型稀土基合金的活化性能优良及对氢化和氢化物分解过程具有催化作用的特点 ,将Zr0 .9Ti0 .1 (Mn0 .35Ni0 .6 5) 2 AB2 型Laves相合金与AB5型混合稀土合金进行机械球磨处理 ,制备了AB5 AB2 复合合金。研究了复合合金的微观结构和电化学性能 ,结果表明 :在AB5 AB2复合合金中 ,AB5粒子与AB2 粒子在表面处相互镶嵌在一起 ,并仍保持原来的晶体结构。复合合金电极的活化周期从AB2 合金的 11周减少到 4周 ,最大放电容量从 14 1mAh·g- 1 增加到 2 18mAh·g- 1 ,而且在活化初期表现出协同效应。 相似文献
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利用高能球磨方法制备纳米Mg2Ni储氢合金,用于高容量MH/Ni电池氢化物电极电化学性能研究。XRD和TEM测试结果表明,机械合金化方法制备Mg2Ni合金的历程为合金化——非晶化——纳米晶化,球磨时间直接影响Mg2Ni合金的结构。高能球磨20h可以制备非晶态Mg2Ni合金,比普通的机械合金化方法制备非晶态Mg2Ni合金的时间减少了约5倍之多;高能球磨30h可以制备纳米晶态Mg2Ni合金,粒径在10nm以下,有团聚现象。研究了Mg2Ni纳米氢化物电极在不同温度下的电化学性能,并从热力学角度就Mg2Ni纳米氢化物电极的某些高温电化学性能进行了解释和推测。实验结果表明:在30~70℃范围内,随着温度增加,氢化物电极的电化学容量逐渐增加,在70℃时电化学容量可达530.5mAh/g,约为30℃放电容量273.2mAh/g的2倍,Mg2Ni纳米氢化物电极具有较好的高倍率放电性能及大电流充放电性能,这表明机械合金化方法制备的Mg2Ni纳米氢化物电极具备电动车用大型MH/Ni电池负极材料的初步条件,但容量衰减严重。 相似文献
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采用XRD、FESEM-EDS、ICP及EIS等方法对Ti0.17Zr0.08V0.34Cu0.01Cr0.1Ni0.3储氢合金的微观结构及电化学性能进行了研究.XRD分析结果表明Ti0.17Zr0.08V0.34Cu0.01 Cr0.1Ni0.3固溶体储氢合金由BCC结构的V基固溶体主相和少量的C14 Laves相组成.FESEM-EDS测试结果表明V基固溶体主相为树枝晶结构,C14 Laves相呈网格状围绕着树枝晶.电化学测试结果表明,Ti0.17Zr0.08V0.34 Cu0.01 Cr0.1Ni0.3氢化物电极在303~343K较宽的温度区间内具有良好放电容量,在343K时电化学容量高达316.5mAh/g;在303K时循环100周次后,其容量为278.2mAh/g,容量保持率为87.0%,表明氢化物电极具有较好的循环稳定性,但其高倍率放电性能较差.Ti0.17Zr0.08V0.34Cu0.01Cr0.1Ni0.3氢化物电极的电化学阻抗谱表明,电极电化学反应的电荷转移电阻(RT)随温度的增加而显著降低,交换电流密度(I0)随温度的增加显著增加.ICP分析结果表明,V和Zr元素向KOH电解质中溶解严重,这可能是Ti0.17Zr0.08V0.34Cu0.01Cr0.1Ni0.3氢化物电极容量衰减的主要原因. 相似文献
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Effect of Cerium on Microstructure and Electrochemical Performance of Ti-V-Cr-Ni Electrode Alloy 总被引:2,自引:0,他引:2
Effect of cerium on the microstructure and electrochemical performance of the Ti0.25V0.35-xCexCr0.1Ni0.3(x=0,0.005)electrode alloy was investigated by X-ray diffraction(XRD),field emission scanning electron microscopy/energy dispersive X-ray spectrometry(FESEM-EDS),and electrochemical impedance spectroscopy(EIS)measurements.On the basis of XRD and FESEM-EDS analysis,the alloy was mainly composed of V-based solid solution with body-centered-cubic structure and TiNi-based secondary phase.Ce did not exist in two phases,instead,it existed as Ce-rich small white particles,with irregular edges,distributed near the grain boundaries of the V-based solid solution phase.Discharge capacity,cycle stability,and high-rate discharge ability of the alloy electrode were effectively improved with the addition of Ce at 293 K.It was very surprising that the charge retention was abnormal with larger discharge capacity after standing at the open circuit for 24 h.EIS indicated that addition of Ce improved the dynamic performance,which caused the charge transfer resistance(RT)to decrease and exchange current density(I0)to increase markedly.The exchange current density of the electrochemical reaction on the alloy surface with Ce addition was about 2.07 and 3.10 times larger than that of the alloy without Ce at 303 and 343 K,respectively.The diffusion coefficient of hydrogen(D)in the bulk alloy electrode decreased with addition of Ce,but it did not decrease so much,and the apparent activation energy(△rH)was far higher than that of the AB5 type alloy. 相似文献
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