A high-capacity re-mg-ti-ni-co-al system ab for a hybrid vehicle ni-mh battery 2 Type hydrogen storage electrode alloy and preparation method thereof

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 invention belongs to the technical field of hydrogen storage alloy materials, in particular to a high-capacity RE-Mg-Ti-Ni-Co-Al AB suitable for Ni-MH batteries of hybrid electric vehicles 2 Type hydrogen storage electrode alloy and its preparation method. Background technique [0002] With the rapid development of hybrid electric vehicles, higher requirements are put forward for the electrochemical performance of nickel-metal hydride (Ni-MH) batteries, especially the energy density. high capacity requirements. At present, the anode materials of Ni-MH batteries that have been commercialized in my country are mainly rare earth-based AB 5 Type hydrogen storage alloy (the A-side elements refer to exothermic metal elements that can form stable hydrides with hydrogen, such as rare earth elements RE, Ti, Zr, Mg, V, etc., and the B-side elements refer to those that are difficult to form hydrides with hydrogen. However, endothermic metal elements with h...

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Problems solved by technology

Especially Rare Earth AB 2 Type hydrogen storage alloy, in terms of its capacity, fully meets the capacity requirements of hybrid electric vehicles, but there are still two problems in actual use: 1) rare earth AB 2 The actual discharge capacity of the type hydrogen storage alloy is much lower than the theoretical capacity, the theoretical capacity of the hydrogen storage alloy is 470 mAh / g, but the actual discharge capacity does not exceed 300 mAh / g, so how to further improve the rare earth AB 2 The actual discharge capacity of 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 ReNi by rapid quenching process 2 (Re= La, Ce, Pr, Mm) alloys, the hydrogen absorption is higher than that of LaNi 5 Alloy, but there is no obvious hydrogen release platform, more than 75% of hydrogen cannot be released

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