JP2002343333A - Nickel hydride battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel hydride battery whose collector plate and elec trode plate are integrally bonded with each other. SOLUTION: The nickel hydride battery is composed of a collector plate made of an iron-based metal, an electrode plate consisting of a positive electrode plate or a negative electrode plate and of a brazing filler metal section made from a nickel-phosphorus compound (Ni-P) formed by solidification after being melted which bonds the collector plate with the electrode plate without melting the collector plate. The nickel hydride battery is a battery low in price and with outstanding battery characteristics due to the bonding with the brazing filler metal made of Ni-P which has high electric conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nickel-metal hydride battery, and more particularly, to a nickel-metal hydride battery in which an electrode plate and a current collector are joined by a brazing material.

[0002]

2. Description of the Related Art Nickel-metal hydride batteries have been used as power sources for various applications because of their long life and high weight energy density and power density.

In a normal nickel-metal hydride battery, a positive electrode and a negative electrode are formed as plate-like electrode plates, and the positive electrode plate and the negative electrode plate are laminated with a separator interposed therebetween to form an electrode body.
An electrode reaction is caused in this electrode body. Extraction of electric power from the electrode body is performed using a pair of current collector plates in which one of the positive electrode plate and the negative electrode plate is integrally joined.

However, in an ordinary nickel-metal hydride battery, since the electrode body is formed by laminating a plurality of layers of a positive electrode plate and a negative electrode plate, the electrode plate cannot be easily joined to the current collector plate. . That is, since the interval between the plurality of electrode plates in a stacked state joined to the current collector plate is narrow, joining using a welding rod has been difficult. Further, when a bonding method involving heating is used in bonding the electrode plate and the current collector plate, it is required to suppress damage to the electrode due to heat.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a nickel-metal hydride battery in which a current collecting plate and an electrode plate are integrally joined.

[0006]

Means for Solving the Problems To solve the above-mentioned problems, the present inventors have developed a nickel-metal hydride battery in which an electrode plate and a current collecting plate are integrally joined with a brazing material made of Ni-P. We found that we could solve the problem.

That is, the nickel-metal hydride battery of the present invention
A current collector plate made of an iron-based metal, an electrode plate made of a positive electrode plate or a negative electrode plate, and a nickel-phosphorus compound (Ni-P) formed by melting and solidifying, and current is collected without melting the current collector plate And a brazing material portion in which the plate and the electrode plate are integrally joined.

In the nickel-metal hydride battery according to the present invention, since the current collector plate and the electrode plate are joined by the brazing material portion made of Ni-P having high electric conductivity, the electrode plate does not lose electric power. Electric power can be extracted from the board. Furthermore, when the brazing material having Ni-P is melted and solidified to form the brazing material, since only the brazing material is melted to form the brazing material, energy for melting the brazing material is used. It can be kept low. As a result, the nickel-metal hydride battery of the present invention is inexpensive and has excellent battery characteristics.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A nickel-metal hydride battery according to the present invention has a current collector, an electrode plate, and a brazing material.

[0010] When the current collector plate is made of an iron-based metal, the current collector plate has sufficient strength and electrical conductivity, so that power generated by an electrode reaction of the positive electrode or the negative electrode can be conducted. Become. The iron-based metal forming the current collector is not particularly limited, and an iron-based metal used as a current collector in a conventional nickel-metal hydride battery can be used.

The electrode plate is made of a positive electrode plate or a negative electrode plate. When the electrode plate is formed of the positive electrode plate or the negative electrode plate, the nickel-metal hydride battery can generate electric power.

The brazing material portion is made of a nickel-phosphorus compound (Ni-P) formed by melting and solidifying, and integrally joins the current collector plate and the electrode plate without melting the current collector plate. That is, since the current collector plate and the electrode plate are integrally joined by the brazing material portion, the power generated by the electrode plate can be taken out to the outside via the current collector plate. In addition, since the brazing material portion is made of Ni-P having high electric conductivity, electric power generated in the electrode plate can be efficiently extracted to the current collector plate.

Further, since the brazing material portion integrally joins the current collector plate and the electrode plate without melting the current collector plate, the brazing material portion is made of only Ni-P.

The nickel-metal hydride battery of the present invention can generate electric power by having a pair of electrode plates including a positive electrode plate and a negative electrode plate, and can extract electric power generated at the electrode plates by the current collector plate. .

Preferably, the brazing material portion is formed by melting and solidifying a brazing material having Ni-P in a state where the electrode plate is in contact with the surface of the current collector plate. That is, the brazing material having Ni-P is melted and solidified in a state where the electrode plate is in contact with the surface of the current collector plate, whereby a brazing material portion made of Ni-P is formed.

The brazing material portion is preferably made of a brazing material having a subeutectic or hypereutectic component composition. When the brazing material has a hypoeutectic or hypereutectic component composition, a sufficient brazing material portion is formed on the surface of the electrode plate.

More specifically, a eutectic composition of 11% P is generally used as Ni-P used as a brazing material, but the material having the eutectic composition has a solidus temperature and a liquidus temperature. Since the temperature is equal, when welding is performed in a very short time, a phase change from a solid to a liquid rapidly occurs near the melting point. Due to this rapid phase change, the brazing material scatters to a portion other than the junction between the current collector plate and the electrode plate, and in the worst case, the scattered brazing material causes a short circuit between the positive electrode and the negative electrode. Further, when the brazing material scatters, the amount of the brazing material at the joint between the current collector plate and the electrode plate becomes insufficient, and sufficient joining strength cannot be obtained.

On the other hand, in the present invention, by using a brazing material having a subeutectic or hypereutectic component composition, even if the brazing material is heated, the temperature between the solidus temperature and the liquidus temperature is maintained. In this case, the brazing material has a relatively high viscosity state of solid-liquid mixing. As a result, the brazing material having a component composition of hypoeutectic or hypereutectic does not scatter even when heated, and smoothly wets the electrode plate in contact therewith, thereby forming a trigger for joining.

The brazing material is preferably melted by local heating. That is, by melting the brazing material by local heating, it is possible to prevent the electrode from being damaged by the heat applied for melting the brazing material.

The local heating is preferably performed by irradiating an electron beam. Since the electron beam has excellent straight-line performance, local heating can be performed.

The brazing material is preferably a plating layer formed on the surface of the current collector plate by a jet plating method. Since the brazing material is formed of the plating layer formed by the jet plating method, the heat treatment does not have to be performed at the time of forming the brazing material, and the current collector plate does not warp. Further, there is no variation in the amount of brazing material to be formed. For this reason, the electrode plate and the current collector plate can be securely joined, and the cost required for manufacturing does not increase.

In the jet plating method, a plating solution is jetted from a nozzle and applied to the surface of a current collector, and a current is applied between the current collector and the nozzle in a state where the plating solution is sprayed.
This is a plating method in which a plating film is deposited only on a portion of the surface of the current collector plate which is in contact with the plating solution.

When a current flows between the nozzle and the current collector,
The current collector is connected to the negative electrode, and the nozzle is connected to the positive electrode. When the current collector is connected to the negative electrode and the nozzle is connected to the positive electrode, ions are reduced on the surface of the current collector and a plating layer is integrally formed on the surface of the current collector.

The jet plating method has an effect that a plating layer can be formed locally because a plating layer can be formed only on a portion that is in contact with a plating solution. Furthermore, the jet plating method sprays a plating solution onto the surface of the current collector plate, so that more metal ions can be supplied to the surface of the current collector plate in a unit time compared to conventional electroplating. Can be formed, and the formation speed of the plating layer can be increased.

The jet velocity at which the plating solution is sprayed onto the surface of the substrate is preferably a uniform jet velocity at the portion where the plating solution is sprayed. In the jet plating method, the metal ions forming the plating layer are supplied to the surface of the current collector plate by a jet, so that when the jet velocity of the plating solution is not uniform, the amount of metal ions supplied to the surface of the current collector plate is reduced. This is because deviation occurs, which causes a problem in accuracy of the thickness of the plating layer formed as a result.

When the jet velocity is increased, the supply amount of metal ions to the surface of the current collector plate increases, and the critical current density increases.
The formation speed of the plating layer can be increased. However, above a certain jet velocity, the value of the limiting current density does not change. This is presumably because the rate-limiting reaction shifts from supply of metal ions to the diffusion layer to transfer of electrons of the metal ions in the electric double layer.

It is preferable that the plating solution is uniformly sprayed on one surface of the current collector plate on which the brazing material is formed at a jet velocity of 0.5 to 8 m / sec. Jet velocity 0.5m /
If the time is less than sec, a sufficient amount of metal ions cannot be supplied to the surface of the current collector, so that the critical current density does not increase and high-speed plating becomes impossible. When the jet velocity is 8
If it exceeds m / sec, the plating solution entrains air, and thus the oxidation deterioration of the plating solution is promoted.

Further, according to the jet plating method, since the brazing material can be formed only in necessary portions, the loss of the plating solution can be suppressed.

Further, since processing such as heat treatment is not required after the brazing material is formed, an increase in cost required for manufacturing the current collector plate can be suppressed.

The plating layer may be formed at one or more ribs extending in the thickness direction of the positive electrode or negative electrode to be joined. By forming the plating layer in a rib shape extending in the thickness direction of the positive electrode and the negative electrode, it is possible to suppress an increase in the plating amount.

When the plating layer is formed in a rib shape, the portion where the plating layer is formed can be limited, and when the positive electrode or the negative electrode is joined, the heating portion of the current collector plate can be limited. It is possible to suppress overheating damage of the active material of the negative electrode.

[0032] The plating layer is preferably made of Ni-P plating. Since the plating layer is made of Ni-P plating, a positive electrode or a negative electrode can be joined to the current collector when forming a nickel-metal hydride battery.

The plating layer is 5 to 10 wt% or 12 to
It is preferable to have 14 wt% of phosphorus and the balance being nickel. When the plating layer has 5 to 10 wt% or 12 to 14 wt% of phosphorus, the melting point of the plating layer is 10%.
The temperature is lower than 00 ° C., and the positive electrode or the negative electrode can be joined to the current collector plate with a small amount of heat. Here, phosphorus is 5-10
When the content becomes Ni, the Ni-P becomes a hypoeutectic component composition, and when the content becomes 12 to 14 wt%, a hypereutectic component composition becomes Ni.

The plating layer is preferably provided with a thickness of 100 to 180 μm, more preferably 120 to 180 μm.
160 μm.

A plating solution for forming a plating layer using the jet plating method includes nickel sulfate, nickel chloride,
It is preferably a solution in which boric acid and hypophosphorous acid are dissolved in water. When the plating solution is composed of a solution of these compounds, nickel ions and phosphorus ions can be supplied to the surface of the current collector plate. These ions are reduced on the surface of the current collector plate to form a plating layer.

It is preferable that nickel sulfate is dissolved in the plating solution at 200 to 500 g / l. Here, the amount of nickel sulfate dissolved is a ratio to water as a solvent. If nickel sulfate is less than 200 g / l, metal ions are not sufficiently supplied to the surface of the current collector plate, and
If it exceeds g / l, it becomes difficult for phosphorus to be eutectoid.

The nickel chloride is preferably dissolved in the plating solution at 20 to 80 g / l. Here, the amount of nickel chloride dissolved is a ratio to water as a solvent, similarly to nickel sulfate. In addition, nickel chloride is 20 g /
When the amount is less than 1, the current efficiency is reduced and the phosphorus concentration tends to be excessive. When the amount exceeds 80 g / l, the phosphorus concentration becomes insufficient.

It is preferable that boric acid is dissolved in the plating solution at 20 to 80 g / l. Here, the amount of boric acid dissolved is a ratio to water as a solvent, similarly to nickel sulfate. If the amount of boric acid is less than 20 g / l, the pH of the plating solution will not be stable, and if it exceeds 80 g / l, boric acid will not be dissolved in the solvent and precipitation will occur.

It is preferable that hypophosphorous acid is dissolved in the plating solution at 2 to 10 g / l. Here, the dissolution amount of hypophosphorous acid is a ratio to water as a solvent, similarly to nickel sulfate. If the amount of hypophosphorous acid is less than 2 g / l, the phosphorus concentration tends to decrease to less than 5% by weight.
If it exceeds g / l, the surface of the plating layer formed by jet plating becomes rough.

The current collector plate preferably has a Ni plating film on the surface. By having the Ni plating film on the surface, the adhesion of the plating layer forming the brazing material to the current collector plate is improved. Further, by having the Ni plating film, rust prevention can be imparted to the current collector plate.

The nickel-metal hydride battery of the present invention only needs to be a battery in which the current collector plate and the electrode plate are integrally joined by a brazing material portion, and other known members may be used. Can be.

As the electrode plate composed of a positive electrode or a negative electrode, a conventionally known electrode plate for a nickel-metal hydride battery can be used.

As the positive electrode plate, for example, a positive electrode current collector composed of a nickel porous plate and NiOO as a positive electrode active material are used.
And a positive electrode active material layer portion having H can be used.

As the negative electrode plate, for example, an electrode having a negative electrode current collector made of an iron plate and a negative electrode active material layer having a hydrogen storage alloy as a negative electrode active material can be used. As this hydrogen storage alloy, for example, La-Ni
Alloy, Ti-Fe alloy, Mg-Ni alloy, Fe-
An alloy such as a Ni-Ti alloy can be given.

Further, a nickel-metal hydride battery can be obtained by enclosing a positive electrode plate and a negative electrode plate in a battery case together with an electrolytic solution in a state of being laminated via a separator.

As the separator and the electrolyte, those conventionally known can be used. As the separator, for example, a porous resin sheet can be used, and as the electrolytic solution, for example, potassium hydroxide (KO)
H) An electrolytic solution composed of an aqueous solution can be used.

Further, in the nickel-metal hydride battery of the present invention, it is preferable that an electrode body in which a plurality of positive electrode plates and a plurality of negative electrode plates are laminated is formed.

As the battery case, a known battery case for a nickel-metal hydride battery can be used.

In the nickel-metal hydride battery of the present invention, since the current collector plate and the electrode plate are joined by the brazing material portion made of Ni—P having high electric conductivity, the electrode plate does not lose power. Electric power can be extracted from the board. Furthermore, when the brazing material portion is formed by melting and solidifying the brazing material having Ni-P, only the brazing material is melted.
Energy for melting the brazing material can be kept low. As a result, the nickel-metal hydride battery of the present invention is inexpensive and has excellent battery characteristics.

[0050]

The present invention will be described below with reference to examples.

(Example) A nickel-metal hydride battery was manufactured as an example of the present invention.

(Current Collecting Plate) The current collecting plate 1 is electrically connected to the joining end 11 to which the electrode plate is joined when the battery is formed, and to the external terminals of the battery and the adjacent battery when the battery is formed. And a terminal unit 12 connected to the terminal unit 12. This current collector 1 is shown in FIG.

The joining end portion 11 has a pair of side end portions 13, 13 opposed to each other and bent perpendicular to the plane where the joining end portion 11 extends, and has a U-shaped cross section.

The joining end 11 is formed of a pair of side ends 1.
Ni-P formed in a convex shape on the surface sandwiched between 3, 13
A brazing material 14 made of a plating layer is formed. The brazing material 14 is formed in a rib shape in a direction perpendicular to the extending direction of the joining end portion 11 and in the thickness direction of the electrode plate joined when the battery is formed. Rib-shaped joining member 1
4 are arranged in parallel with each other.

(Preparation of current collector plate) The current collector plate was manufactured by bending a metal plate into a predetermined shape and then forming a joining member at a joining end by a jet plating method.

First, an SPCE plate is formed in a predetermined shape.
A base material having a curved portion at the side end 13 was formed.

Thereafter, the substrate was subjected to alkali degreasing, acid activity, and Ni strike plating as plating pretreatments. Thereafter, a brazing material was formed by a jet plating method using a plating apparatus in a state in which a portion of the joining end where the joining member was not formed was masked. FIG. 2 shows a plating apparatus for forming a brazing material.

The plating apparatus 2 comprises a jet nozzle 21 for jetting a plating solution vertically upward, a platinum electrode 23 provided at the opening of the jet port 21, a negative electrode with the current collector plate 1 and a positive electrode with the platinum electrode 23. And a case 24 for collecting a plating solution. The plating apparatus 2 is connected to the joining end 1 with a masking plate 22 disposed in contact with the surface of the joining end 11.
1 is arranged to face the opening of the ejection nozzle 21.

Using the plating apparatus 2, the plating solution is sprayed from the ejection nozzle 21 onto the surface of the joining end 11 of the current collector plate 1 while the plating solution is sprayed on the current collector plate 1 and the platinum electrode. 23 was supplied with a current for 10 minutes. The plating conditions were a current density of 80 A / dm ² , a bath temperature of 60 ° C., and a plating solution composition of 350 g / l nickel sulfate, 40 g / l nickel chloride, and 40 g / l boric acid. A solution in which 3 g / l of hypophosphorous acid was dissolved in water was used.

Thereafter, the supply of electric power from the heating section and the ejection of the plating solution from the ejection nozzle 21 were stopped, and the current collector plate 1 was taken out of the plating apparatus 2. The extracted current collector plate had the brazing material 14 formed on the surface of the joint end 11.

(Electrode Plate) For the electrode plate, a conventionally known electrode plate for a nickel-metal hydride battery was used for both the positive electrode plate and the negative electrode plate.

The positive electrode plate has a positive electrode active material layer having NiOOH on the surface of a positive electrode current collector made of a porous nickel plate. Further, the positive electrode plate has no positive electrode active material layer formed at an end portion joined to the current collector plate, and the positive electrode current collector is exposed.

The negative electrode plate has a negative electrode active material layer having a hydrogen storage alloy powder on the surface of a negative electrode current collector made of a perforated iron plate. Further, in the negative electrode plate, the negative electrode active material layer is not formed at the end joined to the current collector plate, and the negative electrode current collector is exposed.

(Nickel-Metal Hydride Battery) The nickel-metal hydride battery of the embodiment has a positive electrode plate 3, a negative electrode plate 4, a separator 5,
And the positive electrode plate 3 and the negative electrode plate 4 constituting the electrode body 6 are respectively joined to a pair of different current collector plates 1, 1.

The separator 5 has a bag shape, and covers the positive electrode plate 3 by inserting the positive electrode plate 3 into the bag with one end of the positive electrode plate 3 exposed. By laminating the positive electrode plate 3 and the negative electrode plate 4 with the separator 5 covering the positive electrode plate 3, an electrode body 6 having a laminated structure in which the separator 5 is interposed between the positive electrode plate 3 and the negative electrode plate 4 is formed. Was done.

In the electrode body 6, the positive electrode plate 3 and the negative electrode plate 4 project in opposite directions. Here, the protruding portion of the positive electrode plate 3 was one exposed end.

In the nickel-metal hydride battery of the embodiment, each of a pair of protrusions from which the positive electrode plate 3 and the negative electrode plate 4 protrude are joined to the current collector plates 1, 1. The current collecting plate 1 is joined by heating with an electron beam from the back side of the joining end 11 in a state where the end of the electrode plate 3 or 4 is in contact with the surface of the joining end 11 on which the brazing material 14 is formed. It was done by Note that the electrode plates 3 or 4 were joined so as to spread in a direction perpendicular to the surface of the joint end 11.

More specifically, when an electron beam is irradiated and heated in a state where the end of the electrode plate 3 or 4 is in contact with the brazing material 14 at the joining end 11, only the brazing material 14 is melted, and the brazing material is melted. The liquid adheres to the surface of the ends of the electrode plates 3 and 4 due to its wettability. As a result, the brazing material melt solidifies, and the electrode plates 3 and 4 are fixed to the surface of the current collector plate 1. In addition, by heating using an electron beam, the bonding end 11
Because only the portion where the brazing material 14 is formed can be heated,
The contacted electrode plate 4 is less likely to cause overheating damage.
Here, the state of the contact portion of the negative electrode plate 4 with the current collector plate 1 is shown in FIGS.

The joint end 11 was irradiated with the electron beam by an electron beam irradiation device manufactured by Mitsubishi Electric Corporation.

The electrode body 6 to which the current collector plate 1 was bonded was sealed in a battery container (not shown) together with a conventionally known aqueous solution of KOH, which is an electrolytic solution for nickel-metal hydride batteries. By the above means, the nickel-metal hydride battery of the example was manufactured.

(Evaluation) An observation was made of a brazing material portion for joining the electrode plate and the current collector plate of the nickel-metal hydride battery of the example. Observation of the brazing material portion was performed by taking a micrograph at a cross section perpendicular to the electrode plate and the current collector plate. Figure 5 shows the shooting results
It was shown to.

FIG. 5 shows that the nickel-metal hydride battery of the embodiment
The current collector plate and the electrode plate are joined only with a brazing material made of Ni-P. This indicates that in the nickel battery of the example, only the brazing material was melted by local heating by the electron beam when the current collector plate and the electrode plate were joined. Further, in the nickel-metal hydride battery of the embodiment, since the electrode plate and the current collector are joined by Ni-P having high electric conductivity, the electric resistance at the junction between the electrode plate and the current collector is reduced. is decreasing. That is, the electric power generated in the electrode plate can be efficiently extracted. As a result,
The nickel-metal hydride battery of the present invention is a nickel-metal hydride battery that has high power characteristics and can be manufactured at low cost.

[0073]

According to the nickel-metal hydride battery of the present invention, since the current collector plate and the electrode plate are joined by the brazing material made of Ni-P having high electric conductivity, no power loss occurs. In addition, electric power can be extracted from the electrode plate.
Furthermore, when the brazing material having Ni-P is melted and solidified to form the brazing material, the brazing material is formed by melting only the brazing material. It can be kept low. As a result, the nickel-metal hydride battery of the present invention is inexpensive and has excellent battery characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing a current collector plate of an example.

FIG. 2 is a diagram showing a configuration of a plating apparatus using a jet plating method.

FIG. 3 is a diagram showing a configuration of a nickel-metal hydride battery.

FIG. 4 is a view showing a joining step of joining an electrode body and a current collector plate.

FIG. 5 is a diagram showing a cross section of a brazing material part of the nickel-metal hydride battery of the example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Current collecting plate 11 ... Joining end 12 ... Terminal part 13 ... Side end 14 ... Brazing material 2 ... Plating apparatus 21 ... Spray nozzle 22 ... Masking plate 23 ... Platinum electrode 24 ... Case 3 ... Positive electrode plate 4 ... Negative electrode plate 5 ... separator 6 ... electrode body

Claims (5)

[Claims] 1. A current collector plate made of an iron-based metal, an electrode plate made of a positive electrode plate or a negative electrode plate, and a nickel-phosphorus compound (Ni-
A nickel-metal hydride battery comprising: P); and a brazing material portion in which the current collector plate and the electrode plate are integrally joined without melting the current collector plate. 2. The nickel-metal hydride battery according to claim 1, wherein the brazing material portion has a subeutectic or hypereutectic component composition. 3. The nickel-metal hydride battery according to claim 1, wherein the brazing material portion is formed by melting and solidifying a brazing material having Ni—P in a state where the electrode plate is in contact with the surface of the current collector plate. . 4. The nickel-metal hydride battery according to claim 1, wherein the brazing material is a plating layer formed on the current collector plate surface by a jet plating method. 5. The nickel-metal hydride battery according to claim 1, wherein the current collector plate has a Ni plating film on a surface.