Ti-V-Nb-Cr-Ni电极合金的微观结构及某些动力学性能研究  

Microstructure and Some Dynamic Performances of Ti-V-Nb-Cr-Ni Electrode Alloy

作　　者：乔玉卿[1] 赵敏寿[1] 侯春平[1] 朱新坚[2] 曹广益[2] 

机构地区：[1]燕山大学亚稳材料科学与工程国家重点实验室 [2]上海交通大学燃料电池研究室,上海200030

出　　处：《无机化学学报》2007年第1期15-20,共6页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金资助项目(No.20171042)

摘　　要：本文采用XRD,FESEM-EDS及电化学阻抗谱(EIS)等方法对V基固溶体Ti0.25V0.34Nb0.01Cr0.10Ni0.30电极合金的微观结构及某些动力学性能,如交换电流密度(i0)、氢的扩散系数(D)等进行了研究。XRD和FESEM-EDS分析测试结果表明:Ti0.25V0.34Nb0.01Cr0.10Ni0.30电极合金由BCC结构的V基固溶体主相和少量的TiNi基第二相组成,其中,V基固溶体主相为树枝晶形状,TiNi基第二相呈网格状围绕着树枝晶。EIS及其等效电路分析结果表明,电极表面电化学反应的电荷转移电阻(RT)随着温度的升高而降低,而交换电流密度和氢在合金本体中的扩散系数随着温度的升高而升高。在343K时的交换电流密度分别为323K和303K的3.6倍和13.6倍,氢的扩散系数略有升高。电化学反应的表观活化能(ΔrH)59.091kJ·mol-1远高于AB5型合金的28.10kJ·mol-1。Ti0.25V0.34Nb0.01Cr0.10Ni0.30合金电极的放电容量在303￣343K较宽的温度区间内随温度的升高而增加,且高温倍率放电(HRD)性能优于低温,当放电电流密度较大时,氢的扩散是放电过程的主要速度控制步骤。Microstructure and some dynamic performances of Ti0.25V0.34Nb0.01Cr0.10Ni0.30 electrode alloy were studied by XRD, FESEM-EDS and EIS measurements. Based on XRD and FESEM-EDS analysis, the alloy is mainly composed of V-based solid solution with BCC structure and TiNi-based secondary phase. V-based solid solution phase looks as a dendrite surrounded by TiNi-based secondary phase. The discharge capacity increases with increasing temperature in a wider temperature region from 303 K to 343 K. The result of electrochemical impedance spectrometry （EIS） indicates that the charge transfer resistance （RT） decreases with increasing temperature, while the exchange current density （io） and the diffusion coefficient of hydrogen （D） in the bulk of the alloy increase with increasing temperature. The exchange current density （io） at 343 K is about 3.6 times and 13.6 times larger than that at 323 K and 303 K, respectively, but diffusion coefficient of hydrogen does not increase so much. The apparent activation energy of the electrochemical reaction on the surface of the electrode alloy is far higher than that for AB5 type alloy. The result of HRD indicates that the diffusion of hydrogen in the bulk of the alloy may be a rate-limiting step during the discharge process at higher discharge current density.

关 键 词：电极合金 NI-MH电池 V基固溶体 电化学阻抗 

分 类 号：Q611.61[生物学—生物物理学] O614[理学—无机化学]