Low-cost high-performance rare-earth-based AB5-type hydrogen storage alloy and preparation method thereof

Abstract

The invention relates to a low-cost high-performance rare-earth-based AB5-type hydrogen storage alloy and a preparation method thereof. The alloy has a general formula: Ml(Ni(1-x-y-w)CoxMnyAlzMw)mMgn, wherein x, y, z, w, m and n present a mol ratio; x is larger than zero and smaller than or equal to 0.1; y is larger than zero and smaller than or equal to 0.2; z is larger than zero and smaller than or equal to 0.2; w is larger than or equal to zero and smaller than or equal to 0.06; m is larger than or equal to 4.8 and smaller than or equal to 5.5; n is larger than zero and smaller than or equal to 0.1; the Ml comprises La and at least one element selected from Ce, Pr, Nd, Sm, Gd, Dy, Y, Ca, Ti and Zr; the content of the La in the Ml is 40-80 percent by weight; accordingly, the content of the La in the alloy is 10-26 percent by weight; and the M comprises at least one element of Cu, Fe, Si, Ge, Sn, Cr, Zn, B, V, W, Mo Ta and Nb. The alloy has high content, long service life, low Co content, low cost and good recovery performance.

Description

technical field [0001] The invention relates to a low-cost and high-performance rare earth system AB for the negative electrode of a nickel-hydrogen battery 5 Type hydrogen storage alloy and its preparation method. Background technique [0002] Hydrogen storage alloys are metal hydrogen storage materials, because they can absorb and release hydrogen safely and reversibly in a large amount (the hydrogen storage density is higher than liquid hydrogen) under appropriate temperature and pressure, and the hydrogen absorption and desorption process is accompanied by certain thermal effects , so it has attracted attention as an energy conversion material and energy storage material related to clean energy-hydrogen energy. As a new type of functional material, the application fields of hydrogen storage alloys are as follows: (1) storage of hydrogen energy and thermal energy; (2) separation, recovery and purification of hydrogen; (3) separation of hydrogen isotopes; (4) civil or mix...

AI Technical Summary

Problems solved by technology

Commercially available high performance AB 5 Type hydrogen storage alloy maximum discharge capacity of 330 ~ 350mAh g -1 (milliamp hours per gram), the cycle life is not less than 300 cycles (cut off when the capacity retention rate is 80%, the same below), and its typical alloy composition is (Ml, Mm) (Ni 0.71 co 0.15 mn 0.08 Al 0.06 ) 5 , expensive Co content accounts for about 10wt% (weight percentage), but it accounts for 30-50% of the cost of alloy raw materials

In recent years, in order to reduce the cost of alloys, AB 5 Low-Co and Co-free research on low-Co-type hydrogen storage alloys, by using: (1) B-side cheap elements Cu, Fe, Sn, etc. to replace Co and Ni alone or in combination, (2) A-side Ti, Zr micro-substitution and Addition, (3) non-stoichiometric ratio to make the alloy obtain a special microstructure, (4) annealing treatment and non-equilibrium rapid solidification preparation process, etc., manufacturers of hydrogen storage alloys and nickel-metal hydride batteries have found a balance between alloy cost and performance , successfully developed a series of low-Co or even Co-free low-cost hydrogen storage alloy products; however, since Co element plays a vital role in improving the cycle life of hydrogen storage alloys, its mechanism mainly has three aspects: (1) Reduce the volume expansion rate of the unit cell during the hydrogen absorption and desorption process of the alloy, (2) inhibit the dissolution of Mn and Al elements in the alloy components in the alkali solution, (3) improve the plasticity and toughness of the alloy, and reduce the Co content must sacrifice The electrochemical performance of the alloy, especially the cycle life; therefore, the maximum discharge capacity of the currently commercially available low-Co and Co-free hydrogen storage alloy products does not exceed 330mAh g -1 , The cycle life is 100 to 250 cycles; while reducing the cost, it also sacrifices the high performance of the alloy

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