Amorphous Ti3Ni2 (Ti2Ni/TiNi) alloy has been prepared by mechanical milling of crystalline Ti3Ni2 alloy, and its electrochemical properties were investigated. The results of charge and discharge test show that the amorphous Ti3Ni2 alloy can resolve the problem of extremely short cycle life of crystalline Ti3Ni2 alloy at high temperature (333 K). The capacity retention rate of amorphous Ti3Ni2 alloy is greatly increased to 88.83% at 333 K compared with the retention rate of its crystalline counterpart 39.47% after 19 cycles. Based on analysis of Tafel polarization, linear polarization, and electrochemical impedance spectroscopy, it is found that the major reason for the improvement is the presence of amorphous Ti3Ni2 alloy, which has much better corrosion resistance compared with its crystalline counterpart.