阅读说明：本技术 镍锌电池的制造方法 (Method for manufacturing nickel-zinc battery ) 是由 西山博史 于 2020-03-20 设计创作，主要内容包括：提供一种能够制造抑制了由枝晶引起的短路的耐久性高的镍锌电池的方法。在此公开的镍锌电池的制造方法包括：准备由正极、多孔质负极集电体和隔膜形成的层叠体的工序；将所述层叠体与溶解了氧化锌的电解液一同收纳于电池壳体中,制作电池组装体的工序；以及对所述电池组装体实施充放电的工序。通过所述充放电来使负极活性物质析出,向所述负极集电体内供给负极活性物质。(Provided is a method for manufacturing a nickel zinc battery having high durability, wherein short-circuiting caused by dendrites is suppressed. The method of manufacturing a nickel zinc battery disclosed herein includes: preparing a laminate formed of a positive electrode, a porous negative electrode current collector, and a separator; a step of preparing a battery assembly by storing the laminate in a battery case together with an electrolyte solution in which zinc oxide is dissolved; and a step of charging and discharging the battery assembly. The negative electrode active material is precipitated by the charge and discharge, and the negative electrode active material is supplied into the negative electrode current collector.)

1. A method of manufacturing a nickel zinc battery, comprising:

preparing a laminate formed of a positive electrode, a porous negative electrode current collector, and a separator;

a step of preparing a battery assembly by storing the laminate in a battery case together with an electrolyte solution in which zinc oxide is dissolved; and

a step of charging and discharging the battery assembly,

the negative electrode active material is precipitated by the charge and discharge, and the negative electrode active material is supplied into the negative electrode current collector.

2. The production method according to claim 1, wherein the porous negative electrode current collector has a three-dimensional network structure.

3. The method according to claim 2, wherein the porous negative electrode current collector is a copper-plated nonwoven fabric.

Technical Field

The invention relates to a method for manufacturing a nickel-zinc battery.

Background

A nickel-zinc battery typically includes a positive electrode containing a positive electrode active material (i.e., nickel hydroxide or nickel oxyhydroxide), a negative electrode containing a negative electrode active material (i.e., zinc or zinc oxide), a separator insulating these electrodes, and an alkaline electrolyte solution. As a specific structure of these electrodes, a structure in which an active material is filled in pores of a porous current collector is known (for example, see patent document 1).

The nickel zinc battery has the advantages of high-rate discharge performance and low-temperature use. In addition, nickel zinc batteries have the advantage of high safety because they use a nonflammable alkaline electrolyte. In addition, the nickel zinc battery has an advantage of a small environmental load because lead, cadmium, or the like is not used.

Disclosure of Invention

Nickel zinc batteries utilize the dissolution-precipitation reaction of zinc in the charge-discharge reactions. Therefore, it has been known that zinc dendrites are generated when the reaction occurs unevenly, and the dendrites penetrate through the separator to cause short-circuiting with the positive electrode when charge and discharge are repeated. Nickel zinc batteries have a problem of low durability due to short circuit caused by dendrites, and a solution to this problem has been desired for a long time.

Accordingly, an object of the present invention is to provide a method capable of manufacturing a nickel zinc battery with high durability in which short circuit caused by dendrite is suppressed.

Disclosed herein is a method of manufacturing a nickel zinc battery, including: preparing a laminate formed of a positive electrode, a porous negative electrode current collector, and a separator; a step of preparing a battery assembly by storing the laminate in a battery case together with an electrolyte solution in which zinc oxide is dissolved; and a step of charging and discharging the battery assembly. The negative electrode active material is precipitated by the charge and discharge, and the negative electrode active material is supplied into the negative electrode current collector.

With this structure, a nickel-zinc battery with high durability can be manufactured, in which short-circuiting due to dendrites is suppressed.

In a preferred embodiment of the method for producing a nickel-zinc battery disclosed herein, the porous negative electrode current collector has a three-dimensional network structure.

With such a structure, the surface area on which the negative electrode active material can be deposited is large, the growth direction of dendrites is dispersed, and short-circuiting due to dendrites is particularly unlikely to occur.

In a preferred embodiment of the method for producing a nickel-zinc battery disclosed herein, the porous negative electrode current collector is a copper-plated nonwoven fabric.

With such a structure, the flexibility of the negative electrode is high, and thus the degree of freedom in designing the negative electrode is increased.

Drawings

Fig. 1 is a flowchart showing the respective steps of a method for manufacturing a nickel-zinc battery according to an embodiment of the present invention.

Fig. 2 is a partial perspective view schematically showing an example of the structure of a nickel zinc battery manufactured by the manufacturing method according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view schematically showing an example of a conventional negative electrode configuration.

Fig. 4 is a cross-sectional view schematically showing an example of a negative electrode form according to an embodiment of the present invention.

Fig. 5 is a sectional view schematically showing another example of the form of the negative electrode in the production method according to the embodiment of the present invention.

Fig. 6 is a graph showing the evaluation results (capacity retention rates) of the cycle characteristics of the nickel zinc batteries of the examples and comparative examples.

Description of the reference numerals

10 positive electrode

16 positive electrode current collecting member

18 positive terminal

20 negative electrode

22 negative electrode current collector

30 diaphragm

40 laminated body

50 Battery case

52 cover

60 liner

70 shim

100 Ni-Zn cell

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Further, matters necessary for the implementation of the present invention (for example, a general structure and a manufacturing process of a nickel-zinc battery which are not characteristic of the present invention) other than the matters specifically mentioned in the present specification can be grasped as design matters by those skilled in the art based on the prior art in the art. The present invention can be implemented based on the content disclosed in the present specification and the technical common knowledge in the art. In the following drawings, members and portions that exhibit the same functions are described with the same reference numerals. In addition, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect actual dimensional relationships.

Fig. 1 shows the respective steps of the method for manufacturing a nickel-zinc battery according to the present embodiment.

The method for manufacturing a nickel-zinc battery of the present embodiment includes: a step (laminate preparation step) S101 of preparing a laminate formed of a positive electrode, a porous negative electrode current collector, and a separator; a step (assembly manufacturing step) S102 of accommodating the laminate in a battery case together with an electrolyte solution in which zinc oxide is dissolved, and manufacturing a battery assembly; and a step (charge/discharge step) S103 of charging and discharging the battery assembly. Here, the negative electrode active material is precipitated by the charge and discharge, and the negative electrode active material is supplied into the negative electrode current collector.

Fig. 2 schematically shows the structure of a nickel zinc battery 100 as an example of the structure of a nickel zinc battery manufactured by the manufacturing method of the present embodiment.

First, the laminate preparation step S101 will be described. In step S101, a laminate 40 of the positive electrode 10, the porous negative electrode current collector 22, and the separator 30 is prepared.

As the positive electrode 10, a conventionally known positive electrode used in a nickel-zinc battery can be used.

Specifically, the positive electrode 10 typically includes a positive electrode current collector and a positive electrode active material supported by the positive electrode current collector.

Examples of the form of the positive electrode current collector include open-pore metals, expanded alloys, mesh, foams, and porous metals Celmet.

As a material constituting the positive electrode current collector, a metal having alkali resistance is preferable, and nickel is more preferable.

As the positive electrode active material, at least one of nickel hydroxide and nickel oxyhydroxide is used. In the positive electrode, the following electrochemical reactions occur by the positive electrode active material.

[ Charge ] Ni (OH)₂+OH^-→NiOOH+H₂O+e^-

[ discharge ] NiOOH + H₂O+e^-→Ni(OH)₂+OH^-

From the viewpoint of improving battery characteristics, zinc, cobalt, cadmium, and the like may be solid-dissolved in the positive electrode active material. From the viewpoint of improving battery characteristics, the surface of the positive electrode active material may be coated with metal cobalt, cobalt oxide, or the like.

In addition, the positive electrode 10 may contain a conductive material, a binder, and the like. That is, in the positive electrode 10, the positive electrode mixture containing the positive electrode active material and other components may be supported by the positive electrode current collector.

Examples of the conductive material include cobalt oxyhydroxide and a precursor thereof.

Examples of the binder include polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), Hydroxypropylmethylcellulose (HPMC), carboxymethylcellulose (CMC), Sodium Polyacrylate (SPA), and the like.

The separator 30 is a member interposed between the positive electrode and the negative electrode, insulating the positive electrode from the negative electrode, and conducting hydroxide ions. As the separator 30, a conventionally known separator used in a nickel zinc battery can be used.

As the separator 30, for example, a porous film made of resin, a nonwoven fabric made of resin, or the like can be used. Examples of the resin include polyolefin (polyethylene (PE), polypropylene (PP), and the like), fluorine-based polymer, cellulose-based polymer, polyimide, nylon, and the like.

The separator 30 may have a single-layer structure or a laminated structure of two or more layers (for example, a three-layer structure in which PP layers are laminated on both sides of a PE layer).

As the separator 30, a separator in which an oxide such as alumina or silica and/or a nitride such as aluminum nitride or silicon nitride is adhered to a porous base material can be used.

In a typical method for manufacturing a nickel-zinc battery, a positive electrode, a negative electrode, and a separator are laminated, but in the present embodiment, in the laminate preparation step S101, a porous negative electrode current collector 22 is laminated instead of the finished negative electrode. Therefore, in the laminate preparation step S101, the negative electrode active material is not substantially added to the pores of the porous negative electrode current collector 22. That is, it is permissible to add a very small amount (for example, 10 vol% or less with respect to the pores) of the anode active material in advance into the pores of the porous anode current collector 22 within a range not impairing the effects of the present invention, but it is preferable that the anode active material is not added into the pores of the porous anode current collector 22 in a usual manner. In the negative electrode of a nickel-zinc battery, the following electrochemical reaction occurs, and therefore the negative electrode active material is at least one of zinc and zinc oxide.

[ Charge ] ZnO + H₂O+2e^-→Zn+2OH^-

[ discharge ] Zn +2OH^-→ZnO+H₂O+2e^-

The form of the porous negative electrode current collector 22 is not particularly limited as long as it has a plurality of through-holes, and examples thereof include open-cell metals, expanded alloys, mesh, foams, and porous metal Celmet. Further, sheets with embossed projections having open tops may be used.

The material constituting the porous negative electrode current collector 22 is preferably a metal having high conductivity, more preferably copper or a copper alloy (e.g., brass), and most preferably copper.

In addition, since at least the surface of the negative electrode current collector 22 has conductivity, the surface may be made of copper or a copper alloy and the inside may be made of another material such as nickel. The material of the inside thereof is not limited to metal, and therefore, a copper-plated nonwoven fabric or the like may also be used as the negative electrode collector 22.

The negative electrode current collector 22 preferably has a three-dimensional network structure because the surface area on which the negative electrode active material can be deposited is large, and the growth directions of dendrites are dispersed, so that short circuits due to dendrites are particularly unlikely to occur. Specifically, foams, porous metals, Celmet, and copper-plated nonwoven fabrics are preferable. Among these, a copper-plated nonwoven fabric is more preferable because of high flexibility and high degree of freedom in designing the negative electrode.

The surface of the porous negative electrode current collector 22 may be plated with a metal such as zinc or tin, and preferably with tin. By such plating, generation of hydrogen from the negative electrode current collector 22 can be suppressed.

The positive electrode 10, the porous negative electrode collector 22, and the separator 30 can be laminated in the same manner as in the case of a normal nickel zinc battery. The separator 30 is interposed between the positive electrode 10 and the porous negative electrode current collector 22.

The number of the positive electrode 10 and the negative electrode collector 22 used in the stacked body 40 is not particularly limited. The laminate 40 may be produced using one positive electrode 10 and one negative electrode current collector 22, or the laminate 40 may be produced using a plurality of positive electrodes 10 and a plurality of negative electrode current collectors 22. Alternatively, the laminate 40 may be prepared by sandwiching one positive electrode 10 between two negative electrode current collectors 22.

Next, the assembly forming step S102 will be described. In step S102, the laminate 40 is housed in the battery case 50 together with an electrolyte (not shown) in which zinc oxide is dissolved, thereby producing a battery assembly.

This step can be performed in the same manner as in a known method except that an electrode body in which the positive electrode, the negative electrode, and the separator are laminated is used instead of the laminated body 40, and an electrolytic solution in which zinc oxide is dissolved in the electrolytic solution is used.

Specifically, for example, first, the battery case 50 including the lid 52 is prepared. A gasket 60 and a gasket 70 are provided on the inner side of the case of the cover 52.

The positive electrode terminal 18 and the negative electrode terminal (not shown) are attached to the battery case 50, respectively.

The positive electrode collector 16 is attached to the positive electrode 10 of the stacked body 40. A negative electrode current collector member (not shown) is attached to the negative electrode current collector 22 of the stacked body 40.

The laminate 40 is inserted into the battery case 50, and the positive electrode 10 and the positive electrode terminal 18 are electrically connected via the positive electrode current collector 16. Similarly, the negative electrode current collector 22 and the negative electrode terminal are electrically connected via a negative electrode current collecting member.

After that, the electrolytic solution is injected into the battery case 50.

As the electrolyte used in the assembly production step S102, an alkali metal hydroxide is generally used as the electrolyte. Examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide, and lithium hydroxide, and among them, potassium hydroxide is preferable.

As a solvent of the electrolytic solution, water is generally used.

The concentration of the electrolyte is not particularly limited, but is preferably 5mol/L or more and 11mol/L or less.

In addition, zinc oxide is dissolved in the electrolytic solution. The higher the zinc oxide concentration in the electrolyte, the greater the battery capacity. Therefore, the concentration of zinc oxide in the electrolyte is preferably 60% or more of the saturation concentration of zinc oxide, more preferably 80% or more of the saturation concentration, and most preferably the saturation concentration of zinc oxide.

Next, the charge and discharge step S103 will be described. In the charge and discharge step S103, the battery assembly is charged and discharged. Since zinc oxide is dissolved in the electrolyte, the dissolved zinc oxide is precipitated by charging and discharging the battery assembly, and the negative electrode active material is supplied into the pores of the negative electrode current collector 22. Thus, the negative electrode 20 was produced, and the nickel-zinc battery 100 was produced. Here, the negative electrode active material is at least one of zinc and zinc oxide.

In the nickel zinc battery 100 manufactured in this way, short circuit due to dendrite is suppressed, and therefore, the nickel zinc battery 100 has high durability. The reason for this is as follows.

Conventionally, a negative electrode has a structure in which a negative electrode mixture layer is provided on a foil-shaped negative electrode current collector, or a structure in which a negative electrode mixture is filled in a porous negative electrode current collector, or the like. In such a structure, dendrites easily grow toward the opposite positive electrode. Fig. 3 shows an example of a conventional negative electrode. In the negative electrode 320 shown in fig. 3, a porous metal is used as the negative electrode current collector 322. The negative electrode current collector 322 has pores filled with a negative electrode mixture 324 containing a negative electrode active material. L in fig. 3 represents the stacking direction of the positive electrode, the negative electrode 320, and the separator. In this embodiment, when dendrites are generated, the direction in which the dendrites can grow is a direction along the stacking direction L as indicated by an arrow in fig. 3. Since the stacking direction L is a direction facing the positive electrode, dendrites are very likely to grow toward the facing positive electrode when charge and discharge are repeated.

In contrast, in the present embodiment, the negative electrode active material is not substantially supplied in advance into the pores of the negative electrode current collector 22, and the negative electrode active material is deposited and supplied into the pores of the negative electrode current collector 22 in the charge and discharge step S103.

Fig. 4 shows an example of the negative electrode 20 of the present embodiment. In the anode 20A shown in fig. 4, an open-pore metal is used as the anode current collector 22A. L in fig. 4 represents the stacking direction of the positive electrode, the negative electrode 20A, and the separator. In the charge and discharge step S103, the negative electrode active material particles 24A are deposited in the pores of the negative electrode current collector 22A. In the case where dendrites are generated, the growth direction is mainly a direction perpendicular to the surface of the pores of the anode current collector 22A (arrow direction in fig. 4). Since the stacking direction L is a direction facing the positive electrode, the surface of the hole does not face the positive electrode in the perforated metal. Therefore, when charge and discharge are repeated, dendrite growth toward the opposite positive electrode is less likely to occur.

Fig. 5 shows another example of the negative electrode 20 in the present embodiment. In the anode 20B shown in fig. 5, a foam having a three-dimensional network structure is used as the anode current collector 22B. L in fig. 5 represents the stacking direction of the positive electrode, the negative electrode 20B, and the separator. In the charge and discharge step S103, the negative electrode active material particles 24B are deposited in the pores of the negative electrode current collector 22B. In the case where dendrites are generated, the growth direction is mainly a direction perpendicular to the pore surface of the anode current collector 22B (arrow direction in fig. 5). In the foam, most of the surface of the pores is not oriented in the direction opposite to the positive electrode (i.e., the direction along the lamination direction L). Therefore, when charge and discharge are repeated, dendrite growth toward the opposite positive electrode is less likely to occur. In fig. 5, the negative electrode current collector 22B has a three-dimensional network structure, and therefore the surface area on which the negative electrode active material can be precipitated is large, and the growth directions of dendrites are dispersed.

As described above, in the present embodiment, the negative electrode active material is not substantially supplied in advance into the pores of the negative electrode current collector 22, and the electrolytic solution contains zinc oxide as the negative electrode active material. In the porous negative electrode current collector 22, at least a part of the surface of the pores (in particular, 50% or more, and more particularly 90% or more of the surface of the pores) is not oriented in the direction facing the positive electrode 10. Therefore, when charge and discharge are repeated, dendrite growth in the direction toward the positive electrode 10 is less likely to occur, and short-circuiting caused by dendrites penetrating the separator and reaching the positive electrode is suppressed. As a result, deterioration of battery characteristics when repeatedly charged and discharged is suppressed, and the durability of the nickel-zinc battery 100 is improved.

The nickel-zinc battery 100 of the present embodiment can be used for various applications, and examples of suitable applications include a backup power supply for home use or industrial use, and a driving power supply mounted on a vehicle such as an Electric Vehicle (EV), a Hybrid Vehicle (HV), and a plug-in hybrid vehicle (PHV).

Examples of the present invention will be described below, but the present invention is not intended to be limited to the scope of the examples.

< example 1>

< preparation of Battery Assembly >

A positive electrode was prepared in which a positive electrode mixture containing nickel hydroxide, polyvinylidene fluoride (PVDF), metallic cobalt, and carboxymethyl cellulose (CMC) was filled in foamed nickel. In the positive electrode mixture, the mass ratio of nickel hydroxide, PVDF, metallic cobalt, and CMC was 90: 3: 4: 3. in addition, the coating amount of the positive electrode mixture was 60mg/cm². The thickness of the positive electrode was 300. mu.m.

As the separator, a polypropylene nonwoven fabric having a thickness of about 150 μm was prepared.

As the porous negative electrode current collector, a current collector having a tin plating layer with a thickness of about 3 μm applied on the surface of the copper foam was prepared.

The positive electrode, the separator, and the porous negative electrode current collector are laminated such that the separator is interposed between the positive electrode and the negative electrode current collector. The laminate was sandwiched between acrylic plates to be restrained.

The mounting terminals are housed in the battery case. The battery assembly is obtained by injecting an electrolyte into the battery case. As the electrolyte, an electrolyte saturated with zinc oxide in a 30 mass% aqueous solution of potassium hydroxide was used.

< evaluation of charging operation and cycle characteristics >

As the 1 st charge-discharge cycle, the battery assembly produced above was subjected to constant current charging at a current value of 1/10C for 10 hours, and then to constant voltage discharging at a current value of 1/5C until 1.2V.

Subsequently, as the 2 nd charge-discharge cycle, constant current charging was performed at a current value of 1/5C for 5 hours, and then constant current discharging was performed at a current value of 1/5C until 1.2V.

Thereafter, as the 3 rd charge-discharge cycle, constant current charging was performed at a current value of 1/2C for 2 hours, and then constant current discharging was performed at a current value of 1/2C until 1.2V.

Thereafter, the 3 rd charge-discharge cycle was repeated, and charge and discharge were performed for a maximum of 100 cycles.

The capacity retention rate (%) was calculated using the values of the discharge capacity at the 1 st charge-discharge cycle and the discharge capacity at the predetermined cycle number. The results are shown in FIG. 6.

< comparative example 1>

The same positive electrode and separator as in example 1 were prepared.

A copper foil having a thickness of 10 μm was prepared as a negative electrode current collector. According to the conventional method, at 22mg/cm²The negative electrode mix layer containing zinc oxide, zinc, carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) is formed thereon. In the negative electrode mixture layer, the mass ratio of zinc oxide, zinc, CMC, and SBR is 90: 10: 1: 4. thus, a negative electrode was produced.

The positive electrode, the separator, and the negative electrode were stacked with the separator interposed therebetween, to obtain an electrode body. The obtained electrode body was sandwiched by acrylic plates to be restrained.

The mounting terminals are housed in the battery case. The battery assembly is obtained by injecting an electrolyte into the battery case. As the electrolyte, an electrolyte saturated with zinc oxide in a 30 mass% aqueous solution of potassium hydroxide was used.

The battery assembly was subjected to the same charge/discharge cycle as in example 1 to determine the capacity retention rate. The results are shown in FIG. 6.

< comparative example 2>

The same positive electrode and separator as in example 1 were prepared.

A negative electrode current collector was prepared by applying a tin plating layer having a thickness of 3 μm to a copper foil having a thickness of 10 μm.

The positive electrode, the separator, and the porous negative electrode current collector are laminated such that the separator is interposed between the positive electrode and the negative electrode current collector. The laminate was sandwiched between acrylic plates to be restrained.

The mounting terminals are housed in the battery case. The battery assembly is obtained by injecting an electrolyte into the battery case. As the electrolyte, an electrolyte saturated with zinc oxide in a 30 mass% aqueous solution of potassium hydroxide was used.

The battery assembly was subjected to the same charge/discharge cycle as in example 1 to determine the capacity retention rate. The results are shown in FIG. 6.

Comparative example 1 is an example of manufacturing a nickel zinc battery including a negative electrode having a conventional general structure. When charge and discharge are repeated, the capacity is rapidly decreased by the generated dendrite.

Comparative example 2 is different from comparative example 1 in that a copper foil having no negative electrode active material layer is used. Furthermore, the copper foil is non-porous. In comparative example 2, the negative electrode active material layer was formed by depositing zinc oxide on the copper foil during charge and discharge, but the negative electrode active material layer was not sufficiently formed.

On the other hand, in example 1, the negative electrode active material layer was formed by precipitation of zinc oxide in the copper foam during charge and discharge, and unlike the comparative example, short circuit due to dendrite was suppressed even after 100 cycles of charge and discharge, and the capacity retention rate was high. This is considered to be because the negative electrode current collector is porous, and thus the growth direction of dendrites is dispersed, and dendrite growth is suppressed.

As described above, according to the method for manufacturing a nickel-zinc battery disclosed herein, a nickel-zinc battery having high durability in which short circuit due to dendrite is suppressed can be manufactured.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The techniques described in the claims include various modifications and changes to the specific examples described above.