A comparative study on the electrochemical performance of rapidly solidified and conventionally cast hydride electrode alloy Zr(NiMnM)2.1

Abstract

The crystalline structure, phase abundance, microstructure and electrochemical properties of hydrogen storage electrode alloy Zr(NiMnM) 2.1 (M=V, Cr) prepared by rapid solidification (melt-spinning) and conventional cast methods have been investigated and compared. Results indicate that conventional cast (CC) alloy is composed of Laves phase, non-Laves phases and a little ZrO 2 , while rapid solidification (RS) alloy are completely composed of Laves phase only. The microscopic structure of RS alloy is completely different from that of the CC alloy. The microstructure of RS alloys is fine grain, while the microscopic structure of CC alloy is coarse dendrite. Obvious differences in electrochemical properties exist in electrodes made of these two differently prepared alloys due to the difference of their phase abundance, composition distribution and microstructure. The discharge capacity of RS alloy is 56 mAh g −1 higher than that CC alloy, it reaches 356 mAh g −1 and its cycle life is much longer than that CC alloy too. But RS alloy are fully only activated after 14 cycles, more difficulty than that CC alloy, which is activated around 9 cycles. As a whole RS (melt-spinning) process improves greatly the comprehensive electrochemical properties of the alloy.