This paper presents a new method of surface modification on LaNi5 hydr ogen storage alloy. The hydrogen alloy was treated in the acid CuSO4 solution co ntaining HF. The effect of HF on surface state of alloy was studied and the elec trochemical properties of modified alloy were investigated. Electrochemical impe dance spectra (EIS) was also applied to analyze the resistance property of alloy electrode after modification. SEM and XRD results showed that HF had corrosive effect on hydrogen alloy, which help copper grain to precipitate on alloy surfac e. EIS analysis showed that modified alloy had lower contact resistance and elec trochemical polarization, which resulted in a higher conductivity and electroche mical activation. Electrochemical testing showed modified alloy had better activ ation behavior and excellent large current discharge ability. Thus it could well satisfy the requirement of the application as power sources on electric vehicle s.
Nickel metal hydride batteries in bipolar design off er significant advantages as a power storage system for electric vehicles. This st udy deals with some aspects in structure design and development of bipolar nicke l metal hydride batteries. An improvement on conventional bipolar structure was made, and some novel sealed bipolar nickel metal hydride batteries with 6 cells were assembled and studied.Testing results showed that the improved structure e ffectively protected the worst single cell of bipolar battery, and led to a bett er pressure and cycle performances of novel batteries compared with conventional ones.In addition, the improved bipolar batteries showed excellent discharge and recharge ability, and low resistance in electrochemical tests. As simulating h ybrid electric vehicle working conditions, the batteries displayed good stabilit y during pulse cycles, which indicated the possibility of being used on electric vehicles.
