AB5 type hydrogen storage alloy, preparation method thereof, nickel-hydrogen alloy electrode and nickel-hydrogen battery

Abstract

The application relates to an AB5 type hydrogen storage alloy and a preparation method thereof, a nickel-hydrogen alloy electrode and a nickel-hydrogen battery. The AB5 type hydrogen storage alloy contains La, Ce, Sm and Zr, Y elements at A sites, and contains Ni, Co, Mn, Al and Cu elements at B sites, and the surface of the hydrogen storage alloy has a needle-shaped Y(OH)3 coating layer, and the stoichiometric ratio B / A of the hydrogen storage alloy is not less than 5.35 and not higher than 5.55. The scheme provided by the application can improve the kinetic performance and thermodynamic performance of the AB5 type hydrogen storage alloy in the hydrogen absorption and release process, accelerate the hydrogen absorption and release rate of the hydrogen storage alloy under low temperature conditions, reduce the pulverization tendency of the hydrogen storage alloy in the hydrogen absorption and release process, prolong the cycle life of the hydrogen storage alloy, and effectively reduce the product cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nickel-hydrogen batteries, in particular to an AB5 type hydrogen storage alloy, a preparation method thereof, a nickel-hydrogen alloy electrode and a nickel-hydrogen battery. BACKGROUND

[0002] The nickel-hydrogen battery is a high-performance battery taking nickel hydride as a positive electrode material and hydrogen storage alloy as a negative electrode material, and releasing electric energy through chemical reaction between the positive electrode and the negative electrode. Due to its high energy density, long service life, good environmental performance and other advantages, it is more and more widely used in consumer electronic products, electric vehicles and other fields.

[0003] The current general nickel-hydrogen battery uses temperature is generally between 0℃ and 50℃. When the temperature is lower than 0℃, the discharge efficiency of the nickel-hydrogen battery gradually decreases; when the temperature is only-40℃, the discharge efficiency of the nickel-hydrogen battery is less than 50%; when the temperature is higher than 50℃, the charging efficiency of the nickel-hydrogen battery is low, the self-discharge rate is high, and the cycle life is short. The battery in the field of vehicle-mounted and outdoor application power supply needs to at least meet the conditions of storage at-40℃-85℃ and work at-40℃-85℃, and also needs to have strong safety and a service life of 5-10 years, but the current general nickel-hydrogen battery is difficult to meet the above requirements at the same time.

[0004] Therefore, it is urgent to design a nickel-hydrogen battery with good discharge performance and cycle life in a special temperature environment. SUMMARY

[0005] To solve or partially solve the problems in the related art, the present application provides an AB5 type hydrogen storage alloy, a preparation method thereof, a nickel-hydrogen alloy electrode and a nickel-hydrogen battery, which have good reaction kinetics and thermodynamic performance at low temperature, long cycle life, and can meet the requirements of wide temperature environment application, hydrogen storage alloy cycle life and hydrogen storage alloy price.

[0006] The first aspect of the present application provides an AB5 type hydrogen storage alloy, which contains La, Ce, Sm, Zr and Y elements at A sites, and contains Ni, Co, Mn and Al elements at B sites, and the surface of the hydrogen storage alloy has a needle-shaped Y(OH)3 coating layer, and the stoichiometric ratio B / A of the hydrogen storage alloy is not less than 5.35 and not more than 5.55.

[0007] In some embodiments of the present application, the hydrogen storage alloy has a nickel-rich layer; preferably, the nickel-rich layer is located below the surface of the hydrogen storage alloy, and the nickel-rich layer is arranged in a spaced manner with the Y(OH)3 coating layer.

[0008] In some embodiments of the present application, the specific surface area of the hydrogen storage alloy is ≥3m 2 / g, and the magnetic susceptibility is ≥1.5emu / g.

[0009] In some embodiments of the present application, the hydrogen storage alloy has a general formula: La a Ce b Sm c Zr d Y (1-a-b-c-d) Ni x Co y Mn z Al u Cu v ; 0.22≤a≤0.54, 0.27≤b≤0.42, 0.10≤c≤0.17, 0.01≤d≤0.02, 4.76≤x≤4.94, 0.06≤y≤0.13, 0.15≤z≤0.20, 0.15≤u≤0.30, 0.05≤v≤0.15, 3.35≤x+y+z+u+v≤5.55.

[0010] In some embodiments of the present application, in the hydrogen storage alloy, 1-a-b-c-d≥0.08; preferably, 0.08≤1-a-b-c-d≤0.15.

[0011] The second aspect of the present application provides a preparation method of the AB5-type hydrogen storage alloy according to the first aspect of the present application, comprising:

[0012] S1, obtaining target raw materials according to the stoichiometric numbers of the elements in the general formula;

[0013] S2, heating and smelting the raw materials under a protective atmosphere, and then using a rapid solidification process to prepare hydrogen storage alloy pieces after forming a molten liquid;

[0014] S3, vacuum heat treating the hydrogen storage alloy pieces, and crushing the hydrogen storage alloy pieces into alloy powders after cooling;

[0015] S4, surface treating the alloy powders, and cleaning and drying the alloy powders to obtain AB5-type hydrogen storage alloy powders.

[0016] In some embodiments of the present application, the step S4 uses an alkaline solution to heat and stir the alloy powders; preferably, the alkaline solution is at least one selected from a sodium hydroxide solution, a potassium hydroxide solution, or a lithium hydroxide solution; the concentration of the alkaline solution is 0.1 mol / L-12 mol / L; preferably, 1 mol / L-10 mol / L; the heating temperature of the step S4 is 30°C-80°C; preferably, 50°C-70°C; the stirring time of the step S4 is 5 min-120 min; preferably, 10 min-60 min.

[0017] In some embodiments of the present application, the particle size of the alloy powders is ≤40 μm.

[0018] The third aspect of the present application provides a nickel-hydrogen alloy electrode comprising the AB5-type hydrogen storage alloy of the first aspect of the present application or the AB5-type hydrogen storage alloy prepared by the method of the second aspect of the present application.

[0019] The fourth aspect of the present application provides a nickel-hydrogen battery comprising the nickel-hydrogen alloy electrode of the third aspect of the present application.

[0020] The technical solution provided by the present application can include the following beneficial effects: by controlling the composition of hydrogen storage alloy elements in the AB5-type hydrogen storage alloy, the elements in the hydrogen storage alloy synergize, which can effectively improve the kinetic and thermodynamic properties of the AB5-type hydrogen storage alloy in the hydrogen absorption and desorption process, accelerate the hydrogen absorption and desorption rate of the hydrogen storage alloy under low temperature conditions, and reduce the pulverization tendency of the hydrogen storage alloy in the hydrogen absorption and desorption process, thereby prolonging the cycle life of the hydrogen storage alloy.

[0021] Further, the needle-shaped Y(OH)3coating layer formed on the surface of the hydrogen storage alloy can further increase the specific surface area of the hydrogen storage alloy, thereby improving the kinetic and thermodynamic properties of the hydrogen storage alloy in the hydrogen absorption and desorption process, thereby improving the low temperature performance of the hydrogen storage alloy; at the same time, the stoichiometric ratio of the hydrogen storage alloy is 5.35-5.55, and the use of hyperstoichiometric ratio design enables the hydrogen storage alloy to form a dispersed second phase, which synergizes with the needle-shaped Y(OH)3coating layer on the surface thereof to catalyze the hydrogen absorption and desorption process of the hydrogen storage alloy, further improve the hydrogen absorption and desorption rate of the hydrogen storage alloy under low temperature conditions, and improve the corrosion resistance of the hydrogen storage alloy, prolong the cycle life of the hydrogen storage alloy, enable the nickel-hydrogen battery prepared from the AB5-type hydrogen storage alloy to be applied in a wide temperature environment, have good low temperature performance and good cycle life, and effectively reduce the product cost, which is conducive to the application and promotion of the hydrogen storage alloy and the nickel-hydrogen battery. BRIEF DESCRIPTION OF DRAWINGS

[0022] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description of exemplary embodiments of the present application taken in conjunction with the accompanying drawings, in which like reference characters refer to the like parts throughout the different views.

[0023] Figure 1 is a scanning electron microscope backscattering image of the AB5-type hydrogen storage alloy shown in Example 1 of the present application;

[0024] Figure 2 is a scanning electron microscope secondary electron image of the AB5-type hydrogen storage alloy shown in Example 1 of the present application. DETAILED DESCRIPTION

[0025] In order that the application can be readily understood, the principles thereof will be described by reference to the following detailed description. Before explaining the application in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of the components set forth in the following description. The application is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the terminology used herein is for the purpose of description and not for the purpose of limitation.

[0026] Where a range of values is provided, it is understood that each intervening value, to the

[0027] Unless otherwise defined, all terms used in disclosing the application, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are now described.

[0028] The temperature of the conventional nickel-hydrogen battery is generally between 0°C and 50°C. When the temperature is below 0°C, the discharge efficiency of the nickel-hydrogen battery gradually decreases; when the temperature is only -40°C, the discharge efficiency of the nickel-hydrogen battery is less than 50%; when the temperature is higher than 50°C, the charging efficiency of the nickel-hydrogen battery is low, the self-discharge rate is high, and the cycle life is short. In the field of vehicle-mounted and outdoor power supply, the battery needs to meet the conditions of storage at a temperature of -40°C to 85°C and work at a temperature of -40°C to 85°C, and also needs to have strong safety and a service life of 5 to 10 years, but the conventional nickel-hydrogen battery is difficult to meet the above requirements at the same time.

[0029] The first aspect of the application provides an AB5 type hydrogen storage alloy, which contains La, Ce, Sm, Zr, Y elements at the A site, and contains Ni, Co, Mn, Al, Cu elements at the B site, and the surface of the hydrogen storage alloy has a needle-shaped Y(OH)3 coating layer, and the stoichiometric ratio B / A of the hydrogen storage alloy is not less than 5.35 and not more than 5.55.

[0030] In order to meet the requirements of the power supply related products for the working ability of the battery in the special temperature environment for the vehicle-mounted and outdoor applications, the hydrogen storage alloy provided in the application has A end of La-Ce-Sm-Zr-Y and B end of Ni-Mn-Al-Co-Cu. The elements La-Ce-Sm-Zr-Y at the A end of the hydrogen storage alloy are easy to react with hydrogen to form stable hydride and release a large amount of heat. The elements Ni-Mn-Al-Co-Cu at the B end of the hydrogen storage alloy have small affinity with hydrogen and are not easy to form hydride. The dissolution of hydrogen in the B end is an endothermic reaction. The interaction between the elements at the A end and the elements at the B end in the hydrogen storage alloy can not only improve the kinetic performance of the hydrogen storage alloy in the hydrogen absorption and release process, so that the hydrogen storage alloy can quickly realize the hydrogen absorption and release process at a lower temperature, but also can improve the hydrogen absorption and release platform of the hydrogen storage alloy. The higher the hydrogen absorption and release platform of the hydrogen storage alloy is, the more excellent the thermodynamic performance of the hydrogen storage alloy at a low temperature is, and the overall low-temperature performance of the hydrogen storage alloy is improved.

[0031] The interaction and influence between the elements in the AB5 type hydrogen storage alloy provided in the application can also inhibit the oxidation and pulverization of the hydrogen storage alloy in the hydrogen absorption and release process, improve the high-temperature corrosion resistance of the hydrogen storage alloy, prolong the cycle life of the hydrogen storage alloy, so that the hydrogen storage alloy and the nickel-hydrogen electrode and the nickel-hydrogen battery containing the hydrogen storage alloy meet the application in a wide temperature environment while taking into account the cycle life.

[0032] The stoichiometric ratio of the hydrogen storage alloy is not less than 5.35 and not more than 5.55. The component ratio design of the stoichiometric ratio is combined with the element composition of the hydrogen storage alloy to form a dispersed second phase in the hydrogen storage alloy, thereby improving the corrosion resistance of the hydrogen storage alloy, reducing the pulverization tendency of the hydrogen storage alloy in the hydrogen absorption and release process, prolonging the cycle life of the hydrogen storage alloy, and accelerating the hydrogen absorption and release rate of the hydrogen storage alloy at a low temperature to further improve the low-temperature performance of the hydrogen storage alloy.

[0033] At the same time, the needle-shaped Y(OH)3 coating layer can effectively improve the specific surface area of the hydrogen storage alloy, thereby improving the kinetic performance of the hydrogen storage alloy in the hydrogen absorption and release process, so that the hydrogen storage alloy can quickly realize the hydrogen absorption and release process at a lower temperature, and further improve the low-temperature performance of the hydrogen storage alloy.

[0034] Among the existing hydrogen storage alloys, the alloys with good low-temperature performance are mainly A2B7 hydrogen storage alloys, but the price of the alloys is generally higher than that of AB5 type hydrogen storage alloys, and the main reasons are as follows: (1) the A2B7 hydrogen storage alloy contains neodymium metal, and the price of the neodymium metal is expensive, and the neodymium metal accounts for 20%-30% of the total mass of the alloy; (2) the A2B7 hydrogen storage alloy must add magnesium element, and the magnesium element has a low melting point and a large saturated vapor pressure, and is easy to volatilize in the alloy smelting process, so that the content of the magnesium element in the alloy is difficult to accurately control, and at the same time, the volatilized magnesium element forms magnesium powder and is easily accumulated on the furnace wall of the smelting furnace to cause magnesium powder explosion, and the safety is low, so the processing cost of the A2B7 hydrogen storage alloy is expensive. Compared with the existing A2B7 hydrogen storage alloy, the hydrogen storage alloy of the present application does not contain neodymium element and magnesium element, greatly reduces the processing cost of the hydrogen storage alloy, improves the safety of the hydrogen storage alloy production process, and at the same time, the low-temperature performance and the cycle life of the hydrogen storage alloy can also reach the same level as the A2B7 hydrogen storage alloy.

[0035] In some embodiments, the hydrogen storage alloy has a nickel-rich layer. The nickel-rich layer also plays a catalytic role in the hydrogen absorption and desorption of the hydrogen storage alloy of the present application. After the hydrogen storage alloy simultaneously forms the nickel-rich layer and the dispersed second phase, the two can further improve the low-temperature performance of the hydrogen storage alloy.

[0036] In some embodiments, the nickel-rich layer is located below the surface of the hydrogen storage alloy, and the nickel-rich layer is spaced apart from the Y(OH)3 coating layer. The nickel-rich layer in the present application is formed at a position several microns below the surface of the hydrogen storage alloy, and is spaced apart from the Y(OH)3 coating layer, which can improve the high-temperature corrosion resistance of the nickel-rich layer and prolong the cycle life of the hydrogen storage alloy.

[0037] In some embodiments, the thickness of the nickel-rich layer can be 1 nm-800 nm; preferably 10 nm-500 nm; and further preferably 50 nm-300 nm.

[0038] In some embodiments, the specific surface area of the hydrogen storage alloy is ≥3 m 2 / g, and the magnetic susceptibility is ≥1.5 emu / g. The Y(OH)3 coating layer formed on the surface of the hydrogen storage alloy effectively increases the specific surface area of the hydrogen storage alloy, and the nickel-rich layer formed several microns below the surface of the hydrogen storage alloy can effectively improve the magnetic intensity of the hydrogen storage alloy; when the specific surface area and the magnetic susceptibility of the hydrogen storage alloy meet the above conditions, the hydrogen storage alloy has high hydrogen absorption and desorption rate, good corrosion resistance, and good cycle life.

[0039] In some embodiments, the general formula of the hydrogen storage alloy is: La a Ce b Sm c Zr d Y (1-a-b-c-d) Ni x Co y Mn z Al uCu v ; the numerical ranges of which are 0.22≤a≤0.54, 0.27≤b≤0.42, 0.10≤c≤0.17, 0.01≤d≤0.02, 4.76≤x≤4.94, 0.06≤y≤0.13, 0.15≤z≤0.20, 0.15≤u≤0.30, 0.05≤v≤0.15; and 5.35≤x+y+z+u+v≤5.55.

[0040] In the present application, the stoichiometric number of the hydrogen storage alloy A end consisting of La-Ce-Sm-Zr-Y is 1, and the stoichiometric number of the hydrogen storage alloy B end consisting of Ni-Mn-Al-Co-Cu is between 5.35-5.55. Therefore, the AB5 type hydrogen storage alloy provided in the present application has a B end stoichiometric number not less than 5.35 and not more than 5.55 than the A end stoichiometric number, i.e. the hydrogen storage alloy in the present application is designed by using a hyperstoichiometric ratio; on the basis of meeting the hyperstoichiometric ratio design, limiting the stoichiometric number of each element in the hydrogen storage alloy within the above range can further play a synergistic effect between each element, improve the low temperature performance and cycle life of the hydrogen storage alloy. At the same time, based on the stoichiometric ratio of each element in the hydrogen storage alloy, the addition amount of each element in the hydrogen storage alloy can be limited, which can not only make the hydrogen storage alloy have good performance, but also effectively control the cost of the hydrogen storage alloy, so that the hydrogen storage alloy can simultaneously consider low temperature performance, cycle life and cost price, etc., which is conducive to the application and promotion of the hydrogen storage alloy.

[0041] In the present application, the proportion of La element is 0.22≤a≤0.54, which can be 0.22, 0.25, 0.30, 0.35, 0.38, 0.39, 0.40, 0.45, 0.50 or 0.54, etc., but is not limited to the values given, and other values not listed in this range are also applicable. The La element in the hydrogen storage alloy of the present application can act together with other elements to improve the hydrogen absorption amount of the hydrogen storage alloy, and can be used in combination with Sm and other elements to adjust the equilibrium pressure of the hydrogen storage alloy after absorbing and desorbing hydrogen.

[0042] In the present application, the proportion of Ce element is 0.27≤b≤0.42, which can be 0.27, 0.30, 0.32, 0.35, 0.40 or 0.42, etc., but is not limited to the values given, and other values not listed in this range are also applicable. The addition of Ce element in the hydrogen storage alloy of the present application can act together with other elements to improve the hydrogen absorption and desorption platform of the hydrogen storage alloy, and increasing the addition amount of Ce element can further improve the hydrogen absorption and desorption platform of the hydrogen storage alloy, thereby further improving the thermodynamic performance of the hydrogen storage alloy at low temperature.

[0043] The proportion of Sm element in the application is 0.10≤c≤0.17, for example, it can be 0.10, 0.11, 0.14, 0.15 or 0.17, etc., but is not limited to the values, and other values not listed in the range are also applicable. The addition of a small amount of Sm element in the hydrogen storage alloy of the application can reduce the pulverization tendency of the hydrogen storage alloy during hydrogen absorption and desorption, prolong the cycle life of the hydrogen storage alloy, and can be used in combination with La and other elements to adjust the equilibrium pressure of the hydrogen storage alloy after hydrogen absorption and desorption.

[0044] The proportion of Zr element in the application is 0.01≤d≤0.02, for example, it can be 0.01 or 0.02, etc., but is not limited to the values, and other values not listed in the range are also applicable. The Zr element in the hydrogen storage alloy of the application can interact with other elements to improve the hydrogen absorption capacity of the hydrogen storage alloy.

[0045] By controlling the stoichiometric number of La, Ce, Sm and Zr elements at the A end of the hydrogen storage alloy, not only can the stoichiometric number range of Y element in the hydrogen storage alloy be limited, but also the mass percentage of each element in the hydrogen storage alloy can be controlled, for example, the added Y element in the hydrogen storage alloy is not less than 1.5% of the mass percentage of the hydrogen storage alloy, so that the interaction and influence between each element in the hydrogen storage alloy are improved, and the low temperature performance and high temperature performance of the hydrogen storage alloy are improved.

[0046] The proportion of Ni element in the application is 4.76≤x≤4.94, for example, it can be 4.76, 4.77, 4.80, 4.82, 4.85, 4.90 or 4.94, etc., but is not limited to the values, and other values not listed in the range are also applicable. The Ni element in the hydrogen storage alloy of the application can interact with other elements to change the crystal structure of the hydrogen storage alloy, thereby improving the hydrogen absorption and desorption performance of the hydrogen storage alloy, and improving the hydrogen absorption and desorption capacity and rate of the hydrogen storage alloy.

[0047] The proportion of Co element in the application is 0.06≤y≤0.13, for example, it can be 0.06, 0.08, 0.10, 0.12 or 0.13, etc., but is not limited to the values, and other values not listed in the range are also applicable. The addition amount of Co element in the hydrogen storage alloy of the application is not more than 2% of the total mass of the hydrogen storage alloy, which can not only effectively control the cost of the hydrogen storage alloy, but also reduce the influence on the discharge rate, and ensure good low temperature discharge performance of the hydrogen storage alloy.

[0048] The proportion of the element Mn in the present application is 0.15≤z≤0.20, for example, it can be 0.15, 0.17, 0.18 or 0.20, etc., but is not limited to the values given, and other values not listed in this range are also applicable. The addition of the element Mn in the hydrogen storage alloy of the present application can act together with other elements to adjust the hydrogen absorption amount of the hydrogen storage alloy and the hydrogen absorption and desorption platform of the hydrogen storage alloy.

[0049] The proportion of the element Al in the present application is 0.15≤u≤0.30, for example, it can be 0.15, 0.20, 0.23, 0.25, 0.28 or 0.30, etc., but is not limited to the values given, and other values not listed in this range are also applicable. The addition of the element Al in the hydrogen storage alloy of the present application can act together with other elements to improve the discharge performance of the hydrogen storage alloy, and at the same time, can replace part of the Ni element in the hydrogen storage alloy, thereby reducing the cost of the hydrogen storage alloy; and can form a stable oxide film on the surface of the hydrogen storage alloy, preventing the hydrogen storage alloy from being oxidized and corroded under high temperature conditions, thereby improving the high temperature performance of the hydrogen storage alloy.

[0050] The proportion of the element Cu in the present application is 0.05≤v≤0.15, for example, it can be 0.05, 0.08, 0.10, 0.12 or 0.15, etc., but is not limited to the values given, and other values not listed in this range are also applicable. The addition of a small amount of the element Cu in the hydrogen storage alloy of the present application can act together with other elements to improve the kinetic performance of the hydrogen storage alloy at low temperature, improve the hydrogen absorption and desorption rate of the hydrogen storage alloy, and at the same time, strengthen the cycle life of the hydrogen storage alloy.

[0051] In some embodiments, in the hydrogen storage alloy, 1-a-b-c-d≥0.08; preferably, 0.08≤1-a-b-c-d≤0.15, i.e., the element Y can be 0.08, 0.10, 0.11, 0.12 or 0.15, etc., but is not limited to the values given, and other values not listed in this range are also applicable. By limiting the amount of the element Y added to the hydrogen storage alloy in the present application, the element Y can fully act together with other elements in the hydrogen storage alloy to improve the low temperature performance of the hydrogen storage alloy.

[0052] In some embodiments, the hydrogen storage alloy can be:

[0053] La 0.38 Ce 0.42 Sm 0.11 Zr 0.01 Y 0.08 Ni 4.94 Co 0.06 Mn 0.15 Al 0.15 Cu 0.05 ;

[0054] La 0.39 Ce0.35 Sm 0.14 Zr 0.01 Y 0.11 Ni 4.85 Co 0.10 Mn 0.17 Al 0.23 Cu 0.10 ;

[0055] La 0.40 Ce 0.27 Sm 0.17 Zr 0.01 Y 0.15 Ni 4.77 Co 0.13 Mn 0.20 Al 0.30 Cu 0.15 。

[0056] The application also provides a preparation method of the AB5-type hydrogen storage alloy, comprising the following steps:

[0057] S1. According to the stoichiometry of each element in the general formula, target raw materials are obtained;

[0058] S2. The raw materials are heated and smelted under a protective atmosphere, and after forming a molten liquid, a hydrogen storage alloy sheet is prepared by using a rapid solidification process;

[0059] S3. The hydrogen storage alloy sheet is vacuum heat treated, and after cooling, it is broken into an alloy powder;

[0060] S4. The alloy powder is surface treated, washed and dried to obtain an AB5-type hydrogen storage alloy powder.

[0061] In some embodiments, in step S1, the mass percentage of each element is calculated according to the chemical formula of the determined structure formula of the AB5-type hydrogen storage alloy, and each element is proportioned according to the mass percentage.

[0062] In some embodiments, in step S2, the protective atmosphere can be an inert atmosphere, for example, helium, argon, etc., to avoid oxidation of each element of the hydrogen storage alloy.

[0063] In some embodiments, the heating temperature of step S2 is 1000-1600°C.

[0064] In some embodiments, the heat treatment temperature of step S3 is 1000-1200°C.

[0065] In some embodiments, in step S4, the alloy powder is subjected to heating and stirring treatment with an alkaline solution. The surface of the hydrogen storage alloy treated with the alkaline solution can form needle-shaped Y(OH)3 with a large specific surface area, which can improve the kinetic performance of the hydrogen absorption and desorption process of the hydrogen storage alloy, so that the hydrogen absorption and desorption process of the hydrogen storage alloy can be quickly realized at a lower temperature, and the low-temperature performance of the hydrogen storage alloy can be improved; at the same time, a nanoscale nickel-rich layer is formed at a few microns below the surface of the hydrogen storage alloy treated, which also plays a catalytic role in the hydrogen storage alloy, and cooperates with the needle-shaped Y(OH)3 coating layer and the dispersed second phase to improve the low-temperature performance of the hydrogen storage alloy.

[0066] In some embodiments, the alkaline solution in step 4 can be selected from one or more of, for example, sodium hydroxide solution, potassium hydroxide solution, lithium hydroxide solution and other alkaline aqueous solutions, which can not only play a surface treatment role, but also reduce the possibility of introducing other elements on the surface of the hydrogen storage alloy that may affect the low-temperature performance and high-temperature performance of the hydrogen storage alloy.

[0067] In some embodiments, the concentration of the alkaline solution in step S4 is 0.1 mol / L to 12 mol / L, preferably 1 mol / L to 10 mol / L. For example, it can be 0.1 mol / L, 0.5 mol / L, 1 mol / L, 5 mol / L, 8 mol / L, 10 mol / L or 12 mol / L, but is not limited to the values given, and other values not listed in this range are also applicable; the heating temperature of step S4 is 30℃ to 80℃, preferably 50℃ to 70℃, for example, it can be 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃, but is not limited to the values given, and other values not listed in this range are also applicable; the stirring time of step S4 is 5 min to 120 min, preferably 10 min to 60 min, for example, it can be 5 min, 10 min, 20 min, 30 min, 50 min, 60 min, 80 min, 90 min or 120 min, but is not limited to the values given, and other values not listed in this range are also applicable.

[0068] When the AB5-type hydrogen storage alloy is prepared by the preparation steps in the present application, the hydrogen storage alloy can form a dispersed second phase, thereby improving the corrosion resistance of the hydrogen storage alloy and prolonging the cycle life of the hydrogen storage alloy; the elements in the hydrogen storage alloy can interact with other elements to improve the hydrogen absorption capacity and hydrogen absorption and desorption rate of the hydrogen storage alloy, thereby improving the low-temperature performance of the hydrogen storage alloy; a needle-shaped Y(OH)3 coating layer with a large specific surface area can be formed on the surface of the hydrogen storage alloy, and a nanoscale nickel-rich layer can be formed below the surface of the hydrogen storage alloy, thereby cooperating to catalyze the hydrogen absorption and desorption process of the hydrogen storage alloy and improving the low-temperature performance of the hydrogen storage alloy.

[0069] In some embodiments, the alloy powder prepared in step 3 has a particle size of ≤40 μm; further, the particle size is not less than 10 μm and not more than 40 μm. By controlling the particle size of the alloy powder, the hydrogen storage alloy powder not only has a high specific surface area, increasing the activity of the hydrogen storage alloy, but also can ensure that the hydrogen storage alloy has good corrosion resistance, improving the cycle life of the hydrogen storage alloy.

[0070] In some embodiments, the hydrogen storage alloy of the present application has a 0.2C discharge capacity of 300±20 mAh / g under half-cell test conditions; a 0.2C discharge efficiency of ≥85% at -40℃; a 1C cycle life of ≥500 cycles at normal temperature, and a hydrogen desorption plateau pressure of not higher than 0.25 MPa and not lower than 0.10 MPa (45℃).

[0071] Unless otherwise specified, "normal temperature" in the present application generally refers to a temperature of (25±2)℃; 1C=300 mAh / g.

[0072] The present application also provides a nickel-hydrogen alloy electrode comprising the AB5-type hydrogen storage alloy described above or the AB5-type hydrogen storage alloy prepared by the preparation method described above.

[0073] The present application also provides a nickel-hydrogen battery comprising the nickel-hydrogen alloy electrode described above.

[0074] The nickel-hydrogen battery of the present application comprises a negative electrode sheet, which comprises a negative electrode core and a negative electrode paste. The negative electrode core is formed by a sheet-shaped metal member having through holes distributed therein, and a punched metal sheet or a sintered substrate obtained by mold forming and sintering of metal powder can be used. The negative electrode paste comprises particles of AB5-type hydrogen storage alloy capable of occluding and releasing hydrogen as a negative electrode active material, a binder, a thickening agent, and other additives.

[0075] The binder functions to bond the hydrogen storage alloy particles and the conductive agent to each other and to bond them to the negative electrode core, and the binder can be selected from, for example, a styrene-butadiene rubber, a hydrophilic polymer, a hydrophobic polymer, and the like.

[0076] The thickening agent imparts viscosity to the negative electrode mixture, which is beneficial for the molding of the negative electrode, and the thickening agent can be selected from, for example, carboxymethyl cellulose.

[0077] The other additives are used to improve the properties of the negative electrode, and can be selected as needed, for example, sodium polyacrylate or the like.

[0078] Further, the negative active material described in the present application can also contain, as needed, a conductive agent, which can be selected from, for example, graphite-based materials such as natural graphite (flaky graphite, etc.), artificial graphite, expanded graphite, etc.; carbon black-based materials such as acetylene black, ketjen black, channel black, furnace black, lamp black, pyrolytic carbon black, etc.; conductive fiber-based materials such as carbon fibers, metal fibers, etc.; and metal powder-based materials such as copper, etc.

[0079] In some embodiments, the amounts of the components added in the negative electrode slurry of the present application can be as follows:

[0080] Hydrogen storage alloy: additive: carboxymethyl cellulose: 48% styrene-butadiene rubber solution: pure water = 100: (0.3-1.0): (0.15-0.3): (1.0-1.5): (3-7).

[0081] In some embodiments, the method for preparing the negative electrode sheet includes mixing a hydrogen storage alloy, a binder, a thickening agent, an additive, and water to prepare a negative electrode slurry; coating the obtained negative electrode slurry on a negative electrode core, and drying, rolling, and cutting to obtain a battery negative electrode sheet.

[0082] The nickel-hydrogen battery of the present application also includes a positive electrode sheet, which includes a positive electrode core and a positive electrode slurry. The positive electrode core is composed of a conductive base having a porous structure, which can be selected from, for example, a metal body in the form of a mesh, sponge, or fiber after plating with nickel, or foamed nickel. The positive electrode slurry includes positive active material particles, a conductive agent, a binder, a thickening agent, and other additives.

[0083] The positive active particles are nickel hydroxide particles or high-nickel hydroxide particles, and in addition, at least one of zinc, magnesium, and cobalt is preferably solid-solved in the nickel hydroxide particles. The conductive agent can be selected from, for example, one or two or more of cobalt compounds such as cobalt oxide (CoO) or cobalt hydroxide (Co(OH)2). The binder serves to bind the positive active material particles, the conductive agent, and the positive electrode additive, and at the same time, can bind the positive electrode slurry to the positive electrode core, and can be selected from, for example, carboxymethyl cellulose, methyl cellulose dispersion, hydroxypropyl cellulose dispersion, etc. The thickening agent imparts viscosity to the positive electrode, which is advantageous for the molding of the positive electrode, and can be selected from, for example, carboxymethyl cellulose. The other additives are used to improve the properties of the positive electrode, and can be selected as needed, and for example, yttrium oxide, zinc oxide, etc. can be used.

[0084] In some embodiments, the amounts of the components added in the positive electrode slurry of the present application can be as follows:

[0085] Nickel hydroxide: additive: conductive agent: carboxymethyl cellulose: polytetrafluoroethylene dispersion: pure water = 100: (0.4-2.0): (0.3-1.8): (0.13-0.21): (0.3-0.5): (20-28).

[0086] In some embodiments, the preparation method of the positive electrode sheet comprises: mixing positive electrode active particles, a conductive agent, a binder, a thickening agent, an additive, and water to prepare a positive electrode slurry; filling the obtained positive electrode slurry into a positive electrode core, drying, rolling, and cutting to obtain a battery positive electrode sheet.

[0087] The nickel-hydrogen battery of the present application further comprises a separator, which is used to separate the positive electrode sheet and the negative electrode sheet. The electrode assembly is formed by winding the positive electrode sheet, the negative electrode sheet, and the separator into a steel shell. The separator may, for example, be a polypropylene separator.

[0088] The nickel-hydrogen battery of the present application further comprises an electrolyte, which may be one or more of an aqueous solution containing sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. The electrode assembly is placed in the electrolyte to form a sealed battery.

[0089] In order to make the present application easier to understand, the present application will be further described in detail below in conjunction with embodiments, which are only illustrative and do not limit the scope of application of the present application. The raw materials or components used in the present application can be prepared by commercial means or conventional methods if not specifically stated.

[0090] Example 1 Preparation of AB5-type hydrogen storage alloy

[0091] 1. The alloy is designed to have the following components: La 0.38 Ce 0.42 Sm 0.11 Zr 0.01 Y 0.08 Ni 4.94 Co 0.06 Mn 0.15 Al 0.15 Cu 0.05 The elements are converted into weight percentage ratios according to the above chemical formula;

[0092] 2. The prepared raw materials are placed in a vacuum induction melting furnace, vacuumized, and then filled with inert gas protection, and inducted to (1300±300) °C; the raw materials are melted to form an alloy melt, refined for 8-10 min, and the molten alloy is prepared into a hydrogen storage alloy sheet by using a strip casting process under vacuum;

[0093] 3. The hydrogen storage alloy sheet is subjected to vacuum heat treatment at a heat treatment temperature of (1100±100) °C, and held for 8-9 h, and then broken into an alloy powder with a particle size of less than 40 μm after furnace cooling;

[0094] 4. The broken alloy powder is put into an alkaline solution for heating and stirring, the stirring time is (30±10) minutes, the alkaline concentration is (5±0.5) mol / L, and the heating temperature is (50±5) ℃. After the stirring, the AB5 type hydrogen storage alloy powder is cleaned with pure water until the cleaning liquid PH value is between 7-9, and then the cleaning is finished. The cleaned AB5 type hydrogen storage alloy powder is vacuum dried and vacuum packaged for storage, and the AB5 type hydrogen storage alloy is prepared.

[0095] Example 2

[0096] The alloy design component is La 0.39 Ce 0.35 Sm 0.14 Zr 0.01 Y 0.11 Ni 4.85 Co 0.10 Mn 0.17 Al 0.23 Cu 0.10 , except that the hydrogen storage alloy component design parameters are different from those of example 1, the others are the same as those of example 1.

[0097] Example 3

[0098] The alloy design component is La 0.40 Ce 0.27 Sm 0.17 Zr 0.01 Y 0.15 Ni 4.77 Co 0.13 Mn 0.20 Al 0.30 Cu 0.15 , except that the hydrogen storage alloy component design parameters are different from those of example 1, the others are the same as those of example 1.

[0099] Comparative Example

[0100] A commercially available A2B7 type low-temperature hydrogen storage alloy is used, and the alloy component and its design parameters are as follows:

[0101] Nd 0.7 Y 0.20 Mg 0.10 Ni 3.40 Al 0.17 .

[0102] The price comparison of examples 1-3 and the comparative examples is shown in table 1.

[0103] Table 1

[0104] Alloy Price (%) Comparative Example 100％ Example 1 48％ Example 2 47.5％ Example 3 49.15

[0105] Electrochemical performance test and hydrogen absorption / desorption plateau test of Examples 1-3 and Comparative Example

[0106] 1. Hydrogen absorption and desorption platform test: Sievelts type automatic equipment test was used, and the test results are shown in Table 5.

[0107] 2. Electrochemical performance test: the prepared AB5 type hydrogen storage alloy was used as a three-electrode (working electrode: hydrogen storage alloy electrode; counter electrode: sintered nickel hydroxide electrode; reference electrode: Hg / HgO electrode), and electrode preparation and test were carried out in a constant temperature water bath at (25±0.5) ℃.

[0108] (1) The electrode preparation method is as follows: 0.1 g of AB5 type hydrogen storage alloy and 0.2 g of nickel carbonyl powder were uniformly mixed and cold-pressed into an electrode sheet.

[0109] (2) The electrode sheet was activated, and the electrodes corresponding to the examples and the comparative examples were activated to the maximum discharge capacity C max , and the activation system is shown in Table 2.

[0110] Table 2

[0111]

[0112] (3) The activated electrode was subjected to -40 ℃ discharge test, and the test system is shown in Table 3, and the test results are shown in Table 5.

[0113] Table 3

[0114]

[0115] (4) After step (2) (3) treatment, the formed battery was obtained, and the charge and discharge cycle test was carried out according to the cycle test method, and the test system is shown in Table 4, and the test results are shown in Table 5.

[0116] Table 4

[0117]

[0118] The electrochemical performance test and hydrogen absorption and desorption platform test results of examples 1-3 and the comparative examples are shown in Table 5.

[0119] Table 5

[0120] 0.2C discharge efficiency at -40°C 1C cycle life Hydrogen desorption plateau pressure (MPa, 45°C) Comparative Example 82.1％ 450 cycles 0.05 Example 1 87.0％ 521 cycles 0.20 Example 2 87.1％ 524 cycles 0.16 Example 3 86.8％ 513 cycles 0.11

[0121] (6) The AB5 type hydrogen storage alloy powder corresponding to example 1 was polished on the surface, and the scanning electron microscope backscattering image was taken (see Figure 1 ). It can be seen from Figure 1 that a color darker diffuse second phase appears in the hydrogen storage alloy phase.

[0122] (7) The AB5-type hydrogen storage alloy powder corresponding to Example 1 was photographed to obtain a scanning electron microscope secondary electron image (see Figure 6). Figure 2 As can be seen from Figure 6, needle-shaped objects were generated on the surface of the hydrogen storage alloy. EDS element analysis of the needle-shaped objects showed that the main component thereof was Y(OH)3. Figure 2

[0123] According to the test results in Tables 2 and 5, it can be seen that:

[0124] The AB5-type hydrogen storage alloy of the present application has a 0.2C discharge efficiency of more than 86% at low temperature (-40°C), a 1C cycle life of more than 510 cycles at normal temperature, and a hydrogen desorption plateau pressure (45°C) of more than 0.1. The A2B7-type hydrogen storage alloy using the prior art has a 0.2C discharge efficiency of 82.1% at low temperature (-40°C), a 1C cycle life of 450 cycles at normal temperature, and a hydrogen desorption plateau pressure (45°C) of 0.05. It can be seen that the low-temperature performance and cycle life of the AB5-type hydrogen storage alloy of the present application can reach or even exceed the performance of the A2B7-type hydrogen storage alloy, but the price thereof is only half of that of the A2B7-type hydrogen storage alloy, which is conducive to industrial application.

[0125] To further verify the application of the AB5-type hydrogen storage alloy provided by the present application as a low-temperature type long-life nickel-hydrogen battery, the present application prepared a nickel-hydrogen battery by using the following method.

[0126] In the method, the positive electrode slurry was prepared by using the positive electrode wet slurry formulation shown in Table 6:

[0127] Table 6

[0128] Nickel hydroxide / g Additive / g Conductive agent / g Carboxymethyl cellulose / g 60% polytetrafluoroethylene dispersion / g Pure water / g 100 1.0 1.0 0.18 0.3 25

[0129] The negative electrode slurry was prepared by using the negative electrode wet slurry formulation shown in Table 7:

[0130] Table 7

[0131] Hydrogen storage alloy / g Additive / g Carboxymethyl cellulose / g 48% butadiene-styrene rubber solution / g Pure water / g 100 0.3 0.2 1.2 5

[0132] The positive electrode slurry was prepared by using the formulation in Table 6, and the positive electrode sheet was made. The negative electrode slurry was prepared by using the formulation in Table 7, and the negative electrode sheet was made. The hydrogen storage alloy in the positive electrode sheet and the negative electrode sheet was the hydrogen storage alloy of Examples 1-3 and the comparative example. The positive electrode sheet, the negative electrode sheet, and a polypropylene separator were wound into a steel shell, and an electrolyte was injected to make a sealed battery.

[0133] The nickel-hydrogen battery prepared by using the hydrogen storage alloy of Examples 1-3 and the comparative example was subjected to formation treatment by using the formation method shown in Table 8:

[0134] Table 8

[0135] Formation method Formation 1 Formation 2 Formation 3 Charging 100mA charging for 10h 100mA charging for 14h 100mA charging for 16h Discharging 200mA discharging to 1.0V 200mA discharging to 1.0V 200mA discharging to 1.0V

[0136] ​The nickel-hydrogen battery after formation was subjected to low-temperature discharge test as shown in Table 9:

[0137] Table 9

[0138]

[0139] The nickel-hydrogen battery after formation was subjected to charge-discharge cycle test as shown in Table 10:

[0140] Table 10

[0141]

[0142] The results of low-temperature discharge test and charge-discharge cycle test of Examples 1-3 and Comparative Examples are shown in Table 11.

[0143] Table 11

[0144] 0.2C discharge efficiency at -40°C Cycle life Comparative Example 80.1％ 800 cycles Example 1 84.2％ 970 cycles Example 2 83.5％ 910 cycles Example 3 84.7％ 936 cycles

[0145] According to the test results shown in Table 11:

[0146] The nickel-hydrogen battery prepared by using the AB5-type hydrogen storage alloy described in the present application has a 0.2C discharge efficiency of 83% or more at low temperature (-40℃) and a 1C cycle life of 910 weeks or more at normal temperature; while the nickel-hydrogen battery prepared by using the existing A2B7-type hydrogen storage alloy has a 0.2C discharge efficiency of 80.1% at low temperature (-40℃) and a 1C cycle life of 800 weeks at normal temperature. It can be seen that the low-temperature performance and cycle life of the wide-temperature nickel-hydrogen battery of the present application can reach or even exceed the performance of the A2B7-type hydrogen storage alloy, which is conducive to its application in special temperature environments, especially in the fields of outdoor power supply, vehicle-mounted battery and the like which have strict requirements on environmental temperature; and the price of the wide-temperature nickel-hydrogen battery of the present application is only half of that of the A2B7-type hydrogen storage alloy, which effectively reduces the price of the wide-temperature nickel-hydrogen battery and is conducive to the popularization and application of the wide-temperature nickel-hydrogen battery.

[0147] It should be noted that the above-described examples are only used to explain the present application and do not constitute any limitation on the present application. The present application has been described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words rather than limiting words. The present application can be modified within the scope of the claims of the present application, and the present application can be revised within the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and examples, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications having the same function.

Claims

1. An AB5-type hydrogen storage alloy, characterized by, The A site of the hydrogen storage alloy contains La, Ce, Sm, Zr, Y elements, the B site contains Ni, Co, Mn, Al, Cu elements, and the surface of the hydrogen storage alloy has a needle-shaped Y(OH)3 coating layer; The general formula of the hydrogen storage alloy is: La a Ce b Sm c Zr d Y (1-a-b-c-d) Ni x Co y Mn z Al u Cu v ; 0.22≤a≤0.54, 0.27≤b≤0.42, 0.10≤c≤0.17, 0.01≤d≤0.02, 1-a-b-c-d≥0.08, 4.76≤x≤4.94, 0.06≤y≤0.13, 0.15≤z≤0.20, 0.15≤u≤0.30, 0.05≤v≤0.15, 5.35≤x+y+z+u+v≤5.

55.

2. The AB5-type hydrogen storage alloy of claim 1, characterized in that: The hydrogen storage alloy has a nickel-rich layer.

3. The AB5-type hydrogen storage alloy of claim 2, characterized in that: The nickel-rich layer is located below the surface of the hydrogen storage alloy, and the nickel-rich layer is arranged separately from the Y(OH)3 coating layer.

4. The AB5-type hydrogen storage alloy of claim 2, characterized in that: The thickness of the nickel-rich layer is 1nm-800nm.

5. The AB5-type hydrogen storage alloy of claim 4, characterized in that: The thickness of the nickel-rich layer is 10nm-500nm.

6. The AB5-type hydrogen storage alloy of claim 5, characterized in that: The thickness of the nickel-rich layer is 50nm-300nm.

7. The AB5-type hydrogen storage alloy of claim 2, characterized in that: The specific surface area of the hydrogen storage alloy is ≥ 3 m 2 / g, and the magnetic susceptibility is ≥ 1.5 emu / g.

8. The AB5-type hydrogen storage alloy of claim 1, characterized in that, The needle-shaped Y(OH)3 coating layer on the surface of the hydrogen storage alloy is obtained by surface treatment of an alkali solution.

9. The AB5-type hydrogen storage alloy of claim 1, characterized in that, In the hydrogen storage alloy, 0.08≤1-a-b-c-d≤0.

15.

10. A method of producing an AB5-type hydrogen storage alloy according to any one of claims 1 to 9, characterized by, Comprising: S1, preparing raw materials corresponding to each element required for the preparation of the hydrogen storage alloy; S2, heating and smelting the raw materials under a protective atmosphere environment, forming a molten liquid, and then treating the hydrogen storage alloy sheet by rapid solidification process; S3, vacuum heat treatment of the hydrogen storage alloy sheet, cooling and crushing into alloy powder; S4, surface treatment of the alloy powder, cleaning and drying to obtain AB5 type hydrogen storage alloy powder.

11. The method of producing an AB5-type hydrogen storage alloy according to claim 10, characterized by, The step S4 uses an alkaline solution to heat and stir the alloy powder.

12. The method of producing an AB5-type hydrogen storage alloy according to claim 11, characterized by, The alkaline solution is at least one selected from sodium hydroxide solution, potassium hydroxide solution or lithium hydroxide solution.

13. The method of claim 11, wherein the AB5-type hydrogen storage alloy is prepared by the steps of: preparing a master alloy by mixing a rare earth element, a transition metal, and a metalloid element; and adding a rare earth element to the master alloy. The concentration of the alkaline solution is 0.1 mol / L-12 mol / L.

14. The method of producing an AB5-type hydrogen storage alloy according to claim 13, characterized by, The concentration of the alkaline solution is 1 mol / L-10 mol / L.

15. The method of claim 11, wherein the AB5-type hydrogen storage alloy is prepared by the steps of: preparing a master alloy by mixing a rare earth element, a transition metal, and a metalloid element; and adding a rare earth element to the master alloy. The heating temperature of step S4 is 30℃-80℃.

16. The method of producing an AB5-type hydrogen storage alloy according to claim 15, characterized by, The heating temperature of step S4 is 50℃-70℃.

17. The method of claim 11, wherein the AB5-type hydrogen storage alloy is prepared by the steps of: preparing a master alloy by mixing a rare earth element, a transition metal, and a metalloid element; and adding a rare earth element to the master alloy. The stirring time of step S4 is 5min-120min.

18. The method of producing an AB5-type hydrogen storage alloy according to claim 17, characterized by, The stirring time of step S4 is 10min-60min.

19. The method of claim any one of claims 10 to 18, wherein the AB5-type hydrogen storage alloy is prepared by the following steps: The particle size of the alloy powder is ≤40μm. ​ 20. A nickel-hydrogen alloy electrode, characterized by, AB5 type hydrogen storage alloy of any one of claims 1-9 or AB5 type hydrogen storage alloy prepared by the preparation method of any one of claims 10-18.

21. A nickel-hydrogen battery, characterized by, The nickel-hydrogen alloy electrode of claim 20.

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