JP2015203119A - Hydrogen storage alloy, nickel hydrogen storage battery and production method of hydrogen storage alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen storage alloy capable of keeping power output characteristics of a nickel hydrogen storage battery at a high level, a nickel hydrogen storage battery provided with the hydrogen storage alloy as the negative pole electrode and a production method of a hydrogen storage alloy.SOLUTION: A hydrogen storage alloy is composed of ABtype alloy: element A is based on a rare earth element; and element B is based on nickel and contains aluminum and/or manganese. In the cross section of the hydrogen storage alloy, the ratio of regions where aluminum and manganese are present in relatively high concentrations is 0.5% or higher. The hydrogen storage alloy is used as the negative pole electrode of a nickel hydrogen storage battery.

Description

  The present invention relates to a hydrogen storage alloy, a nickel-metal hydride storage battery including the hydrogen storage alloy as a negative electrode, and a method for producing the hydrogen storage alloy.

  In general, nickel-metal hydride storage batteries having high energy density and excellent reliability are widely used as power sources for portable devices and portable devices, and as power sources for electric vehicles and hybrid vehicles. The nickel-metal hydride storage battery is composed of a positive electrode mainly composed of nickel hydroxide, a negative electrode mainly composed of a hydrogen storage alloy, and an alkaline electrolyte containing potassium hydroxide and the like.

  The hydrogen storage alloy constituting the negative electrode of such a nickel metal hydride storage battery is pulverized by repeated expansion and contraction in the hydrogen storage / release cycle. Micronization is particularly likely to occur when there is segregation in which the concentration distribution of intermetallic compounds or metal elements constituting the hydrogen storage alloy becomes non-uniform. When the hydrogen storage alloy is pulverized, the corrosion is accelerated by the alkaline electrolyte in accordance with the increase in the surface area and the life is shortened. That is, the segregation of the hydrogen storage alloy is a cause of reducing the cycle life of the nickel metal hydride storage battery. Thus, conventionally, a technique for improving the corrosion resistance of the hydrogen storage alloy with respect to the alkaline electrolyte by suppressing segregation of the hydrogen storage alloy and making it difficult to produce fine powder has been proposed (see, for example, Patent Document 1).

JP-A-5-156382

  However, in the case where pulverization is made difficult to improve the corrosion resistance of the hydrogen storage alloy, the increase in the surface area accompanying the pulverization of the hydrogen storage alloy is suppressed, so that the exposed area of nickel that functions as a catalyst is reduced. The increase is suppressed, and the power output characteristics of the nickel metal hydride storage battery when used in the nickel metal hydride storage battery may not be sufficiently obtained. Further, if the corrosion of the hydrogen storage alloy is suppressed, the dissolution of the components other than nickel that functions as a catalyst in the hydrogen storage alloy is suppressed, and the increase in the exposed area of nickel is also suppressed. The power output characteristics of the nickel-metal hydride storage battery when used in the case may not be sufficiently obtained.

  In general electrical products, the charging rate is used even in a range where the load is high for the battery, such as near 0% or near 100%. Therefore, pulverization / corrosion is likely to occur near 0% or 100%, so that the above-described problems are unlikely to occur. However, in the case of a hybrid vehicle (including a plug-in hybrid vehicle), since the charge rate usage range is 20% to 80%, pulverization and corrosion are unlikely to occur, and the above-described problems are likely to occur.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a hydrogen storage alloy capable of maintaining high power output characteristics of a nickel metal hydride storage battery, and a nickel including the hydrogen storage alloy as a negative electrode. It is providing the manufacturing method of a hydrogen storage battery and a hydrogen storage alloy.

A hydrogen storage alloy that solves the above-mentioned problem is a hydrogen storage alloy made of an AB ₅ series alloy, wherein the A element has a rare earth element as a main component, the B element has nickel as a main component, and at least one of aluminum and manganese. And the ratio of the region where aluminum and manganese are present in a relatively high concentration in the cross section in the cross section of the hydrogen storage alloy is 0.5% or more.

  According to the said structure, the ratio of the area | region where aluminum and manganese exist in comparatively high concentration in a cross section is ensured moderately. Therefore, the power output characteristics of the nickel-metal hydride storage battery using the hydrogen storage alloy can be improved by increasing the surface area accompanying the pulverization of the hydrogen storage alloy.

As a preferable configuration of the hydrogen storage alloy, a ratio of a region where aluminum and manganese are present in a relatively high concentration in the cross section is 4.0% or less.
According to the said structure, the upper limit of the ratio of the area | region where aluminum and manganese exist in comparatively high concentration in a cross section is restrict | limited. Therefore, by adding a certain limit to the likelihood of corrosion in hydrogen storage alloys, it is possible to achieve both corrosion resistance to electrolytes in hydrogen storage alloys and power output characteristics of nickel-metal hydride batteries using this hydrogen storage alloy. Can be achieved.

As a preferable structure of the hydrogen storage alloy, both aluminum and manganese are contained.
According to the said structure, the ratio of the area | region where both aluminum and manganese exist in a comparatively high density | concentration in a cross section is ensured moderately. Therefore, the power output characteristics of the nickel-metal hydride storage battery using the hydrogen storage alloy can be further improved by increasing the surface area accompanying the pulverization of the hydrogen storage alloy.

  As a preferred configuration of the hydrogen storage alloy, when the cross section is divided into a plurality of regions, the standard deviation of the ratio of the regions where aluminum and manganese are present in a relatively high concentration in each region is smaller than the average value of the same ratio .

  According to the said structure, it can suppress that at least one of aluminum and manganese exists unevenly in a cross section. Therefore, it is possible to promote a more stable increase in surface area accompanying the pulverization of the hydrogen storage alloy.

A nickel-metal hydride storage battery that solves the above-described problems is a nickel-metal hydride storage battery that includes a hydrogen storage alloy as a negative electrode, and the hydrogen storage alloy having the above-described configuration is used as the hydrogen storage alloy.
According to the above configuration, the power output characteristics of the nickel-metal hydride storage battery can be improved by providing the negative electrode using the hydrogen storage alloy that is likely to be pulverized and corroded.

As a preferable configuration of the nickel-metal hydride storage battery, the nickel-metal hydride storage battery is mounted on a hybrid vehicle including an internal combustion engine and a motor as drive sources, and supplies electric power to the motor.
According to the above configuration, the output characteristics can be improved while maintaining the reliability of the power supplied to the motor serving as the drive source of the hybrid vehicle.

As a preferable configuration of the nickel-metal hydride storage battery, a charge rate is used in a range of 20% to 80%.
Generally, pulverization of the hydrogen storage alloy is unlikely to occur under the condition that the usage range of the charging rate of the nickel metal hydride storage battery is within 20% to 80%. In this regard, according to the above configuration, the ratio of the region where at least one of aluminum and manganese is present in a relatively high concentration in the cross section is appropriately secured, so that even under such conditions, hydrogen storage is possible. The alloy is pulverized. As a result, the power output characteristics of the nickel-metal hydride storage battery using the hydrogen storage alloy can be improved by increasing the surface area accompanying the pulverization of the hydrogen storage alloy. Therefore, even under the condition where the usage range of the charging rate of the nickel-metal hydride storage battery is within 20% to 80%, a configuration that improves the output characteristics of the power supplied to the motor serving as the drive source of the vehicle can be suitably realized.

Method for producing a hydrogen-absorbing alloy to solve the above problems is a method for producing a hydrogen-absorbing alloy comprising AB ₅ type alloy, a rare earth element as a main component of the A element, and nickel as a main component of the element B, A preparation step of preparing a raw material composition containing at least one of aluminum and manganese as a component constituting the B element in a predetermined composition, and a melting and quenching method for the raw material composition prepared in the preparation step, Generating a hydrogen storage alloy so that a ratio of a region where aluminum and manganese are present in a relatively high concentration in the cross section of the hydrogen storage alloy is 0.5% or more.

  According to the said manufacturing method, the improvement of the output characteristic of the electric power of the nickel hydride storage battery using a hydrogen storage alloy can be aimed at.

  According to the present invention, the power output characteristic of the nickel-metal hydride storage battery can be maintained high.

The graph which shows the correlation with the segregation rate of aluminum and manganese in hydrogen storage alloy, and DC-IR (DC internal resistance) at -30 degreeC about one Embodiment of a nickel hydride storage battery.

Hereinafter, an embodiment of a nickel metal hydride storage battery will be described.
The nickel metal hydride storage battery is a sealed battery, and is a battery used as a power source for driving a motor in a hybrid vehicle having two power sources of an engine and a motor. This nickel-metal hydride storage battery includes, for example, a predetermined number of negative electrode plates composed of a hydrogen storage alloy and a predetermined number of positive electrode plates composed of nickel hydroxide via a separator made of an alkali-resistant resin nonwoven fabric. The laminated electrode group is connected to a current collector plate and is housed in a resin battery case together with an electrolyte mainly composed of potassium hydroxide.

Next, the hydrogen storage alloy used for the negative electrode plate will be described.
The hydrogen storage alloy has an AB ₅ type crystal structure, and in this embodiment, MmNi ₅ (Mm: Misch metal) is used as a prototype, and a part of Ni (nickel) is replaced with another element. ing. Misch metal is an alloy of rare earth elements such as La (lanthanum) and Ce (cerium). As an element that substitutes Ni, for example, at least one element selected from Co (cobalt), Mn (manganese), Fe (iron), Cu (copper), and Ti (titanium) can be used. In this embodiment, an alloy containing Mm, Ni, Co, Al, and Mn is used as the hydrogen storage alloy.

Hereinafter, examples will be described in detail. In this example, a nickel metal hydride storage battery was produced under the following conditions, and its characteristics were evaluated.
The hydrogen storage alloy was produced by the following method. First, a misch metal prepared by alloying a mixture of rare earth elements such as La, Ce, Pr (praseodymium), Nd (neodymium), and Sm (samarium), specifically, a lanthanum element was prepared. And as a preparatory process, this misch metal and Ni, Co, Mn, and Al were mix | blended so that it might become a predetermined composition, and the raw material composition was prepared. Further, as a production process, a hydrogen storage alloy was produced by performing a so-called melt quenching method in which the prepared raw material composition was melted and the cooling rate from the molten state to solidification was 1000 ° C./second or more. In this case, the melted raw material composition is rapidly cooled to produce a hydrogen storage alloy having a small variation in composition component distribution. In addition, by adjusting the weight ratio of Al and Mn to the entire hydrogen storage alloy, the ratio of the cross-sectional locations where Al and Mn are segregated and exist at a relatively high concentration in the cross section of the hydrogen storage alloy is controlled. The And the produced | generated hydrogen storage alloy was grind | pulverized with the ball mill, and hydrogen storage alloy powder was produced.

  Next, the hydrogen storage alloy powder was immersed in an alkaline aqueous solution and stirred, and then washed and dried. Furthermore, a polyvinyl alcohol solution was added to the dried hydrogen storage alloy powder and kneaded to prepare a paste. And this paste was apply | coated to the punching metal, and the negative electrode plate was produced by drying, rolling, and cut | disconnecting.

For the positive electrode plate, a positive electrode plate was prepared by filling a foamed nickel substrate with an active material paste mainly composed of nickel hydroxide, followed by drying, rolling and cutting. Then, a plurality of the positive and negative electrode plates described above are laminated via a separator made of a non-woven fabric of alkali-resistant resin, and housed in a battery case together with an alkaline electrolyte mainly composed of potassium hydroxide (KOH). Thus, a nickel metal hydride storage battery was produced.
(Measurement method of internal resistance (DC-IR) against direct current)
First, charging is performed at a normal temperature until the state of charge (SOC) of the nickel metal hydride storage battery reaches 60%. And after cooling a nickel hydride storage battery to -30 degreeC, the direct current internal resistance (DC-IR) of a nickel hydride storage battery is used as "(DELTA) V / current, using the voltage drop ((DELTA) V) at the time of discharging for 5 second with a fixed electric current value. Calculated by “value”.
(Measurement method of segregation rate of Al and Mn in hydrogen storage alloy)
The segregation rate X of Al and Mn in the hydrogen storage alloy is calculated using the distribution of elements measured under predetermined conditions by an electron beam microprobe analyzer (EPMA). An electron beam microprobe analyzer JXA-8100 (manufactured by JEOL) is used for the measurement of the element distribution. In the present embodiment, acceleration voltage = 15 kV, irradiation current = 0.1 μA, and observation magnification = 400 times are employed as the predetermined conditions. Then, under this predetermined condition, an X-ray intensity signal specific to Al is detected from the cross section of the hydrogen storage alloy, and when the value is 60 CPS or more, Al is segregated in the cross section to a relatively high concentration. It is determined that it exists. Further, under this predetermined condition, an X-ray intensity signal specific to Mn is detected from the cross section of the hydrogen storage alloy, and when the value is 20 CPS or more, Mn segregates at the cross section and the concentration is relatively high. It is determined that it exists. And in the cross section of the hydrogen storage alloy, Al is segregated and the ratio of the cross-section portions determined to be present at a relatively high concentration, and Mn is segregated and exists at a relatively high concentration. The total value with the ratio of the cross-sectional locations determined as is measured as the segregation rate X.

  The values of 60 CPS and 20 CPS are values set so as to detect a value that is twice or more the average level of the alloy cross section. In other words, the “region existing at a relatively high concentration” in the claims refers to a region where Al or Mn exists at a concentration twice or more the average concentration of the entire alloy cross section.

  The concentration of Al or Mn is preferably 4 times or less of the average concentration of the entire alloy cross section. This is because if it exceeds 4 times, the concentration distribution becomes non-uniform. A concentration exceeding 4 times indicates a value exceeding 87 CPS when the EPMA value is Al, and a value exceeding 57 CPS when the value is Mn. In this example, there is no region showing such a value. It was.

The segregation rate X can be adjusted by the ratio of Al and Mn in the alloy. That is, the segregation rate X can be increased by increasing the ratio of Al and Mn.
In addition, when the cross section of the hydrogen storage alloy to be measured is equally divided into N (9 in this embodiment) regions, Al and Mn segregate in each region to a relatively high concentration. The ratio of the area of the existing part is calculated as the segregation rates X1 to XN for each region. The ratio of the standard deviation δX of the segregation rates X1 to XN with respect to the average value of these segregation rates X1 to XN is calculated as the segregation variation (variation coefficient) Xr. The segregation variation Xr can be adjusted by the casting speed of the melt quenching method. That is, the segregation variation Xr can be lowered by slowing down the casting speed.
(Measurement result)
About the nickel metal hydride storage battery of a present Example, the correspondence of the segregation rate of aluminum and manganese in a hydrogen storage alloy and the measurement result of DC-IR is shown in FIG.

  As shown in FIG. 1, in this example, four measurement points P1, P2, P3, and P4 are measured for the correspondence between the segregation rates of Al and Mn and DC-IR. The segregation rate and DC-IR value at each measurement point P1, P2, P3, P4 are P1 (0.2, 20.5) and P2 (0.6, 19.0) in order from the measurement point with the lowest segregation rate. ), P3 (1.2, 18.6), P4 (2.8, 18.2). Then, based on these measurement points P1, P2, P3, P4, an approximate curve L indicating the correlation between the segregation rate and the DC-IR in the nickel-metal hydride storage battery of this example is calculated.

  In the present embodiment, it is understood based on the approximate curve L that the DC-IR is 19.5 mΩ or less when the segregation rate is in the range of 0.5% or more. When DC-IR is 19.5 mΩ or less, it is suitable as output characteristics required for a hybrid vehicle. Of the measurement points P1, P2, P3, and P4, the DC-IR values at the three measurement points P2, P3, and P4 at which the segregation rate is 0.5% or more are substantially constant. On the other hand, the DC-IR value at the measurement point P1 where the segregation rate is less than 0.5% is greatly different from the DC-IR values at the other measurement points P2, P3, and P4.

  In this example, the range in which the value of the segregation rate in the hydrogen storage alloy is 4% or less is a preferable range. When the value of the segregation rate exceeds 4%, Al and Mn are easily corroded. In this case, since Al and Mn are melted and deposited, and there is a possibility that a short circuit may occur when a nickel metal hydride storage battery is used, it is not preferable. Therefore, by adding a certain limit to the likelihood of corrosion in the hydrogen storage alloy in this way, the corrosion resistance to the electrolyte in the hydrogen storage alloy and the power output characteristics of the nickel metal hydride storage battery using this hydrogen storage alloy To achieve both.

  In this example, the values of the segregation variation Xr at the four measurement points P1, P2, P3, and P4 are P1 (100%), P2 (68%), and P3 (59) in order from the measurement point with the lowest segregation rate. %) And P4 (24%). That is, the value of the segregation variation Xr at all the measurement points P1, P2, P3, and P4 is set to 100% or less. Therefore, by ensuring the uniformity of the distribution of Al and Mn in the hydrogen storage alloy, variation in the characteristics is suppressed. In particular, the value of the segregation variation Xr at the measurement points P2, P3, P4 of the present example is set to 70% or less. Therefore, the uniformity of Al and Mn distribution in the hydrogen storage alloy is further ensured, and variation in the characteristics is particularly suppressed.

Next, the effect | action of the nickel hydride storage battery mentioned above is demonstrated.
As for the hydrogen storage alloy, when the segregation rate X of Al and Mn increases, pulverization and corrosion are likely to occur. Therefore, the reaction rate is improved as the exposed area of Ni to the electrolytic solution increases. As a result, the power output characteristic of the nickel-metal hydride storage battery using the hydrogen storage alloy is improved, so that the DC-IR value of the nickel-metal hydride battery is lowered. According to the nickel metal hydride storage battery used in the above examples, when the segregation ratio X of Al and Mn in the hydrogen storage alloy is in the range of 0.5% or more, the DC-IR becomes 19.5 mΩ or less. Was confirmed. Therefore, when the nickel-metal hydride storage battery is mounted on a hybrid vehicle, the power output characteristics of the nickel-metal hydride storage battery using the hydrogen storage alloy are sufficient if the segregation rate of Al and Mn in the hydrogen storage alloy is in the range of 0.5% or more. It will be sufficient.

  In addition, as for the hydrogen storage alloy, when the segregation variation Xr of Al and Mn is increased, the uniformity of Al and Mn distribution is not ensured, and the characteristics tend to vary. Then, according to the nickel metal hydride storage battery used in the above example, when the value of the segregation variation Xr of Al and Mn in the hydrogen storage alloy is 100% or less, that is, when the cross section of the hydrogen storage alloy is divided into a plurality of regions, When the standard deviation δX of the segregation rates X1 to XN, which is the ratio of the regions where Al and Mn are present in a relatively high concentration, is set to be smaller than the average value of the segregation rates X1 to XN, the hydrogen storage alloy It was confirmed that the power output characteristics of the nickel hydride storage battery used were stable. Therefore, if the segregation variation Xr of Al and Mn in the hydrogen storage alloy is in the range of 100% or less, the reliability of the power output characteristics of the nickel hydride storage battery using the hydrogen storage alloy can be sufficiently obtained. Further, since the segregation variation Xr is set to 70% or less, the reliability of the output characteristics is further sufficient.

  Generally, when a nickel metal hydride storage battery is mounted on a hybrid vehicle, the use range of the charge rate of the nickel metal hydride storage battery is 20% to 80%, unlike a general electric product that extends to near 0% or 100%. Will fit in. Since pulverization / corrosion of hydrogen storage alloys occurs mainly in environments where the load on the battery is high, such as near 0% or 100%, the pulverization and corrosion of hydrogen storage alloys within this usage range of the charge rate. Is unlikely to occur. In this regard, according to the nickel metal hydride storage battery used in the above example, the output characteristics of the power of the nickel metal hydride storage battery using the hydrogen storage alloy with the segregation rate of Al and Mn in the hydrogen storage alloy being in the range of 0.5% or more. By improving, the output characteristics of the electric power of the nickel-metal hydride storage battery using the hydrogen storage alloy can be sufficiently obtained even when the usage range of the charging rate falls within 20% to 80%. The reason why the charge rate of the nickel metal hydride storage battery mounted on the hybrid vehicle is used in the range of 20% to 80% is to prevent overcharge / overdischarge.

As described above, according to the nickel-metal hydride storage battery of the above embodiment, the following effects can be obtained.
(1) Since the segregation ratio X of Al and Mn in the hydrogen storage alloy is set in a range of 0.5% or more, a region where Al and Mn are present in a relatively high concentration in the cross section of the hydrogen storage alloy The ratio is moderately secured. Therefore, the power output characteristics of the nickel-metal hydride storage battery using the hydrogen storage alloy can be improved by increasing the surface area accompanying the pulverization of the hydrogen storage alloy.

  (2) The segregation ratio X of Al and Mn in the hydrogen storage alloy is set in a range of 4.0% or less. Therefore, by adding a certain limit to the likelihood of corrosion in hydrogen storage alloys, it is possible to achieve both corrosion resistance to electrolytes in hydrogen storage alloys and power output characteristics of nickel-metal hydride batteries using this hydrogen storage alloy. Can be achieved.

  (3) Since the value of the segregation variation Xr of Al and Mn in the hydrogen storage alloy is set to 100% or less, it is possible to suppress the presence of at least one of Al and Mn in the cross section of the hydrogen storage alloy. . Therefore, it is possible to promote a more stable increase in surface area accompanying the pulverization of the hydrogen storage alloy.

(4) By providing a negative electrode using a hydrogen storage alloy that is likely to be pulverized and corroded, it is possible to improve the power output characteristics of the nickel-metal hydride storage battery.
(5) The nickel metal hydride storage battery is mounted on a hybrid vehicle including an internal combustion engine and a motor as drive sources, and supplies electric power to the motor. Therefore, the output characteristics can be improved while maintaining the reliability of the power supplied to the motor serving as the drive source of the hybrid vehicle.

  (6) Output of power supplied to the motor that is the driving source of the vehicle even when the charging range of the nickel metal hydride storage battery is within the range of 20% to 80% where the hydrogen storage alloy is less likely to be pulverized and corroded. The structure which improves a characteristic can be implement | achieved suitably.

  (7) A hydrogen storage alloy in which the uniformity of Al and Mn distribution is ensured by performing a melting and quenching method on a raw material composition containing Al and Mn in a predetermined composition and having a segregation variation Xr of 100% or less. Can be obtained. Thereby, the increase in the output characteristics of the nickel-metal hydride storage battery due to the pulverization and corrosion of the hydrogen storage alloy can be reliably caused.

In addition, the said embodiment can also be implemented with the following forms.
In the above embodiment, the ratio of cross-sectional locations where Al segregates and exists at a relatively high concentration in the cross section of the hydrogen storage alloy, and Mn segregates and exists at a relatively high concentration. The total value with the ratio of the cross-sectional locations is defined as the segregation rate X. However, when the hydrogen storage alloy contains only one element of Al and Mn, the cross section in which one element of Al and Mn segregates and exists at a relatively high concentration in the cross section of the hydrogen storage alloy. The ratio of the locations may be defined as a segregation rate, and the value of this segregation rate may be set to a range of 0.5% or more. Even in this case, the ratio of the region where Al or Mn is present in a relatively high concentration in the cross section in the cross section of the hydrogen storage alloy is appropriately secured. Therefore, the power output characteristics of the nickel-metal hydride storage battery using the hydrogen storage alloy can be improved by increasing the surface area accompanying the pulverization of the hydrogen storage alloy.

  L: approximate curve, P1, P2, P3, P4: measurement points.

Claims (8)

A hydrogen storage alloy composed of an AB _5- based alloy,
The element A contains a rare earth element as a main component, and the element B contains nickel as a main component and contains at least one of aluminum and manganese.
The hydrogen storage alloy, wherein a ratio of a region where aluminum and manganese are present in a relatively high concentration in the cross section in the cross section of the hydrogen storage alloy is 0.5% or more.   The hydrogen storage alloy according to claim 1, wherein a ratio of a region where aluminum and manganese are present in a relatively high concentration in the cross section is 4.0% or less.   The hydrogen storage alloy according to claim 1 or 2, comprising both aluminum and manganese.   When the cross section is divided into a plurality of regions, the standard deviation of the ratio of the regions where aluminum and manganese are present in a relatively high concentration in each region is smaller than the average value of the ratios. The hydrogen storage alloy according to item. A nickel-metal hydride storage battery comprising a hydrogen storage alloy as a negative electrode,
The nickel hydride storage battery using the hydrogen storage alloy as described in any one of Claims 1-4 as said hydrogen storage alloy.   The nickel metal hydride storage battery according to claim 5, wherein the nickel hydride storage battery is mounted on a hybrid vehicle including an internal combustion engine and a motor as drive sources and supplies electric power to the motor.   The nickel-metal hydride storage battery according to claim 6, wherein the charge rate is in a range of 20% to 80%. A method for producing a hydrogen storage alloy comprising an AB ₅ alloy,
A preparation step of preparing a raw material composition containing a rare earth element as a main component of the A element, nickel as a main component of the B element, and at least one of aluminum and manganese as a component constituting the B element in a predetermined composition When,
The ratio of the region where aluminum and manganese are present in a relatively high concentration in the cross section in the cross section of the hydrogen storage alloy is 0.5% or more by the melt quenching method for the raw material composition prepared in the preparation step A production process for producing a hydrogen storage alloy so as to produce a hydrogen storage alloy.

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