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 micros...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.展开更多
The microstructure and electrochemical properties of Ti0.17Zr0.08V0.35Cr0.10Ni0.30 alloy were investigated. The alloy was found to be consisted of V-based solid solution phase with bcc structure and C14 Laves phase wi...The microstructure and electrochemical properties of Ti0.17Zr0.08V0.35Cr0.10Ni0.30 alloy were investigated. The alloy was found to be consisted of V-based solid solution phase with bcc structure and C14 Laves phase with hexagonal structure. SEM-FEG results show that C14 Laves phase precipitates between bcc phases. V and Cr essentially exist in bcc phase, Ti and Ni mainly in C14 Laves phase, as proved by EDX data. The electrochemical properties prove that the discharge capacity of Ti0.17Zr0.08V0.35Cr0.10Ni0.30 alloy electrode decreases slightly with increasing temperature, but it keeps high discharge capacity at 343 K. At the same time, the charge-transfer resistance decreases and the high rate dischargeability increases as temperature increases.展开更多
基金Project supported by the National Natural Science Foundation of China(20171042)
文摘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.
文摘The microstructure and electrochemical properties of Ti0.17Zr0.08V0.35Cr0.10Ni0.30 alloy were investigated. The alloy was found to be consisted of V-based solid solution phase with bcc structure and C14 Laves phase with hexagonal structure. SEM-FEG results show that C14 Laves phase precipitates between bcc phases. V and Cr essentially exist in bcc phase, Ti and Ni mainly in C14 Laves phase, as proved by EDX data. The electrochemical properties prove that the discharge capacity of Ti0.17Zr0.08V0.35Cr0.10Ni0.30 alloy electrode decreases slightly with increasing temperature, but it keeps high discharge capacity at 343 K. At the same time, the charge-transfer resistance decreases and the high rate dischargeability increases as temperature increases.
