High-capacity RE-Mg-Ti-Ni-Co-Al system AB2 type hydrogen storage electrode alloy applied to Ni-MH batteries of hybrid electric vehicles and preparation method of alloy

Abstract

The invention relates to a high-capacity RE-Mg-Ti-Ni-Co-Al system AB2 type hydrogen storage electrode alloy applied to Ni-MH batteries of hybrid electric vehicles. The chemical composition of the alloy is La1-xRExMg1-yTiyNi4-z-mCozAlm, wherein the chemical component of an A side element is La1-xRExMg1-yTiy; the chemical component of a B side element is Ni4-z-mCozAlm; x, y, z and m in the formula are atomic ratios; x is larger than or equal to 0.1 and smaller than or equal to 0.4; y is larger than or equal to 0.01 and smaller than or equal to 0.1; z is larger than or equal to 0.1 and smaller than or equal to 0.3; m is larger than or equal to 0.05 and smaller than or equal to 0.2; RE is selected from at least one of Ce, Sm, Y, Nd and Pr except La. A preparation method of the high-capacity RE-Mg-Ti-Ni-Co-Al system AB2 type hydrogen storage electrode alloy comprises the following steps: sensing, heating and smelting in vacuum and carrying out inert gas protection to prepare a uniform and consistent quickly-quenched alloy sheet, annealing a small quantity of amorphous phases formed by quickly quenching, and then thoroughly crystallizing the amorphous phases, thereby effectively inhibiting hydrogen-inducing amorphization phenomenon in the subsequent electrochemical process of absorbing and desorbing hydrogen. With combination of the component design and the preparation process, the electrochemical hydrogen storage property of the alloy is improved; the process is easy to master and is suitable for large-scale production; the maximum discharge capacity of the prepared alloy is 435mAh / g, which is 92% of the theoretical discharge capacity; the obvious hydrogen-inducing amorphization phenomenon is not found after performing electrochemical charging and discharging cycle for 300 times.

Description

Technical field [0001] The present invention is a technology field in hydrogen storage alloy materials, and specially involves a high-capacity RE-MG-TI-CO-CO-AL system that is suitable for hybrid vehicles NI-MH batteries 2 Hydrogen storage electrode alloys and preparation methods. Background technique [0002] With the rapid development of hybrid vehicles, the electrochemical properties of nickel-metal hydrogen (NI-MH) batteries have put forward higher requirements, especially energy density, and then proposed to the negative electrode material of the NI-MH battery-hydrogen storage alloyHigh -capacity requirements.At present, my country has realized commercial Ni-MH battery negative materials mainly about rare earth base AB 5 Hydrogen storage alloys (its A -side element refers to the permanent metal element that can form stable hydrogenia with hydrogen, such as rare earth element RE, TI, ZR, MG, V, etc.However, heat -absorbing metal elements with hydrogen catalytic activity, such...

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Problems solved by technology

In particular, the rare earth AB2 type hydrogen storage alloy fully meets the capacity requirements of hybrid electric vehicles in terms of its capacity, but there are still two problems in actual use: 1) Rare earth AB The actual discharge capacity of type 2 hydrogen storage alloy is much lower than the theoretical capacity. The theoretical capacity of this hydrogen storage alloy is 470 mAh / g, but the actual discharge capacity does not exceed 300 mAh / g. The actual discharge capacity of >2 type hydrogen storage alloy is one of the research directions

2) The hydrogen storage alloy system has a prominent hydrogen-induced amorphization phenomenon, which directly leads to the decline of the reversible hydrogen absorption and desorption capacity of the alloy.

Miyamura et al. prepared amorphous ReNi2 (Re = La, Ce, Pr, Mm) alloys by rapid quenching process, and their hydrogen absorption was higher than that of LaNi5 alloys. , but there is no obvious hydrogen release platform, and more than 75% of hydrogen cannot be released

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