JP7724274B2 - Nickel-zinc battery - Google Patents

Description

The present invention relates to a nickel-zinc battery.

Known zinc batteries include nickel-zinc batteries, air-zinc batteries, and silver-zinc batteries. Nickel-zinc batteries, for example, are aqueous batteries that use an aqueous electrolyte such as a potassium hydroxide solution, making them highly safe. The combination of zinc and nickel electrodes provides a high electromotive force for an aqueous battery. Furthermore, nickel-zinc batteries offer excellent input/output performance and low cost, making them suitable for industrial applications (e.g., backup power sources) and automotive applications (e.g., hybrid vehicles). Patent Document 1 discloses technology related to zinc plates used as the negative electrodes of sealed nickel-zinc batteries. The zinc plates described in Patent Document 1 are constructed by filling a porous mat made of copper or a copper alloy, or a porous mat made by copper-plating a resin foam, with an active material containing at least one of metallic zinc and zinc oxide and a binder.

Japanese Unexamined Patent Publication No. 7-6758

Copper has traditionally been widely used for the negative electrode current collector of zinc batteries, as in the zinc plate described in Patent Document 1. This is because copper has good electrical conductivity and high corrosion resistance. However, due to various factors, such as manufacturing costs, there are cases where a negative electrode current collector whose main constituent material is another material that can be substituted for copper is desired. One aspect of the present invention aims to provide a nickel-zinc battery having a negative electrode current collector whose main constituent material is another material that can be substituted for copper.

A nickel-zinc battery according to one aspect of the present invention comprises a positive electrode and a negative electrode having a current collector. The current collector has a substrate primarily containing carbon steel and a tin-plated film covering at least a portion of the surface of the substrate.

In the above-mentioned nickel-zinc battery, the thickness of the tin plating film may be 0.1 μm or more and 5 μm or less.

One aspect of the present invention provides a nickel-zinc battery having a negative electrode current collector whose main constituent material is a material that can be substituted for copper.

1A is a schematic diagram showing an embodiment of a zinc battery negative electrode 1. FIG. 1A is a front view showing the zinc battery negative electrode 1, and FIG. 1B is a cross-sectional view taken along line Ib-Ib in FIG. 1A. 1A is a graph showing the discharge capacity at each discharge rate for the nickel-zinc batteries of the Examples and Comparative Examples, and FIG. 1B is a graph showing the discharge capacity retention rate at each discharge rate for the nickel-zinc batteries of the Examples and Comparative Examples. 1 is a graph showing the relationship between the discharge capacity retention rate and the discharge rate.

In this specification, numerical ranges indicated using "to" indicate ranges that include the numerical values before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. "A or B" may include either A or B, or both. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. In this specification, when multiple substances corresponding to each component are present in the composition, the content of each component refers to the total amount of those multiple substances present in the composition, unless otherwise specified. Furthermore, in this specification, the terms "film" and "layer" encompass structures that are formed over the entire surface as well as structures that are formed only partially when observed in a plan view.

Embodiments of the present invention are described in detail below. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of its gist. The sizes of the components in each figure are conceptual, and the relative size relationships between the components are not limited to those shown in each figure.

Figure 1 is a schematic diagram showing a zinc battery negative electrode 1 of this embodiment. Figure 1(a) is a front view showing a zinc battery negative electrode 1 of this embodiment, and Figure 1(b) is a cross-sectional view taken along line Ib-Ib in Figure 1(a). As shown in Figures 1(a) and 1(b), the zinc battery negative electrode 1 includes a current collector (negative electrode current collector) 2 and a negative electrode material layer 3. The current collector 2 forms a conductive path for current from the negative electrode material layer 3. The current collector 2 includes a substrate 21 and a tin-plated film 22.

The substrate 21 primarily contains carbon steel, and in one example, is made solely of carbon steel. The structure of the substrate 21 is not particularly limited and may be, for example, a flat plate or sheet. It may also have a three-dimensional mesh structure composed of foam metal, expanded metal, metal fiber felt, or the like. As an example, the substrate 21 shown in the figure has multiple holes 21a penetrating the substrate 21 in the thickness direction. The multiple holes 21a are two-dimensionally dispersed in a plane perpendicular to the thickness direction of the substrate 21. In this case, the substrate 21 may be a punched metal made of carbon steel. Carbon steel is electrically conductive and alkali-resistant, and is also stable at the reaction potential of the negative electrode. The carbon (C) content of the carbon steel is, for example, 0.001% by mass or more and 0.15% by mass or less. In addition to carbon (C), the carbon steel may also contain at least one of manganese (Mn), phosphorus (P), and sulfur (S). In one example, the manganese (Mn) content is 0.001% by mass or more and 0.60% by mass or less, the phosphorus (P) content is 0.001% by mass or more and 0.05% by mass or less, and the sulfur (S) content is 0.001% by mass or more and 0.05% by mass or less. The substrate 21 may be, for example, a cold-rolled steel plate or a processed cold-rolled steel plate. The processing may be, for example, bending, pressing, and/or drawing. The cold-rolled steel plate may be, for example, SPCC. According to the standard, the carbon (C) content of SPCC is 0.15% by mass or less, the manganese (Mn) content is 0.60% by mass or less, the phosphorus (P) content is 0.100% by mass or less, and the sulfur (S) content is 0.050% by mass or less. The thickness of the substrate 21 may be, for example, 0.01 mm or more and 0.5 mm or less. The shape of the base material 21 as viewed from the front may be various shapes, such as a rectangle, a square, etc. The area of the base material 21 as viewed from the front may be, for example, 2000 mm ² or more and 20000 mm ² or less.

The tin plating film (tin film) 22 covers all or part of the surface of the substrate 21. When at least a portion of the substrate 21 is covered with the tin plating film 22, oxidation of the substrate 21 can be suppressed. Furthermore, at the negative electrode, a side reaction occurs in which the electrolyte decomposes, generating hydrogen gas. However, when at least a portion of the substrate 21 is covered with the tin plating film 22, the progression of this side reaction can be suppressed. The thickness of the tin plating film 22 may be, for example, 0.1 μm or more and 5 μm or less.

The volume ratio of carbon steel in the zinc battery negative electrode 1 is preferably 8% or more and 18% or less. The volume ratio here is a value calculated by the following formula:
Volume ratio=(volume of the current collector in the coated portion of the negative electrode material layer 3)/(volume of the negative electrode material layer 3)×100
When the volume fraction of carbon steel is 8% or more, the diffusion resistance can be kept low, and good discharge performance can be obtained. When the volume fraction of carbon steel is 18% or less, the influence of the relatively high electrical resistance of carbon steel can be suppressed, and good discharge performance can be obtained. Note that while the specific electrical resistance of copper (Cu), which is used in conventional zinc battery negative electrodes, is 1.7×10 ⁻⁸ (Ω·m), the specific electrical resistance of SPCC is 9.7×10 ⁻⁸ (Ω·m).

The negative electrode material layer 3 is a layer formed from a negative electrode material. The negative electrode material layer 3 is supported on the current collector 2 by filling the mesh (multiple holes 21a) of the current collector 2 with the negative electrode material. The negative electrode material layer 3 contains a zinc-containing component. Examples of zinc-containing components include metallic zinc, zinc oxide, and zinc hydroxide. The zinc-containing component functions as a negative electrode active material in zinc batteries and can also be referred to as a raw material for the negative electrode active material. To achieve better life performance, the content of the zinc-containing component is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more, based on the total mass of the negative electrode material. To achieve better life performance, the content of the zinc-containing component is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, based on the total mass of the negative electrode material.

The negative electrode layer 3 may further contain additives such as a binder (binding agent) and a conductive material. Examples of binders include hydrophilic and hydrophobic polymers. Specific examples of binders that can be used include polytetrafluoroethylene (PTFE), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), polyethylene oxide, polyethylene, and polypropylene. A single binder can be used, or multiple binders can be used in combination. The viscosity of the binder may be, for example, 3000 to 6000 cp at room temperature (25°C) in a 2% aqueous solution, or approximately 25 cp at room temperature (25°C) in a 60% aqueous solution. The binder content is, for example, 0.5 to 10 parts by mass per 100 parts by mass of the zinc-containing component. Examples of conductive materials include indium compounds such as indium oxide. The conductive material content is, for example, 1 to 20 parts by mass per 100 parts by mass of the zinc-containing component.

One method for producing the zinc battery negative electrode 1 described above is to prepare a current collector 2, place a negative electrode material paste on the current collector 2, and then dry the paste. The negative electrode material paste may be placed on the current collector by, for example, rolling the negative electrode material paste with a roller to form a sheet and attaching it to the current collector. The negative electrode material paste may be placed on and/or inside the current collector 2 by, for example, applying or filling the negative electrode material paste onto the current collector 2. The method for applying or filling the negative electrode material paste is not particularly limited and may be selected appropriately depending on the shape of the current collector 2, the shape of the negative electrode material layer, etc. The negative electrode material layer made of the negative electrode material is formed by drying the negative electrode material paste layer. The negative electrode material layer may be densified by pressing, etc., as necessary. The negative electrode material paste contains a negative electrode material raw material and a solvent (e.g., water). The negative electrode material paste is obtained by adding a solvent (e.g., water) to the negative electrode material raw material and kneading them. Raw materials for the negative electrode include zinc-containing components, additives, etc.

Next, we will explain a nickel-zinc battery as an example of a zinc battery of this embodiment in which the above-mentioned zinc battery negative electrode 1 is used. In a nickel-zinc battery, the negative electrode is a zinc (Zn) electrode and the positive electrode is a nickel (Ni) electrode.

The nickel-zinc battery (e.g., nickel-zinc secondary battery) of this embodiment includes, for example, a battery case, an electrode group (e.g., an electrode plate group) and an electrolyte housed in the battery case. The nickel-zinc battery may be either formed or unformed. If the nickel-zinc battery is an unformed nickel-zinc battery, the electrodes (negative and positive electrodes) are unformed electrodes, and if the nickel-zinc battery is a formed nickel-zinc battery, the electrodes are formed electrodes.

The electrode group includes, for example, a negative electrode (e.g., a negative electrode plate), a positive electrode (e.g., a positive electrode plate), and a separator disposed between the two electrodes. The electrode group may include multiple negative electrodes, positive electrodes, and separators. The multiple negative electrodes and multiple positive electrodes may be connected to each other, for example, with straps. The negative electrode has the configuration of the zinc battery negative electrode 1 described above. The separator is, for example, a separator having a flat plate or sheet shape. Examples of separators include polyolefin-based microporous membranes, nylon-based microporous membranes, oxidation-resistant ion-exchange resin membranes, cellophane-based recycled resin membranes, inorganic-organic separators, and polyolefin-based nonwoven fabrics.

The positive electrode comprises a positive electrode current collector and a positive electrode material supported on the positive electrode current collector. The positive electrode current collector forms a conductive path for current from the positive electrode material. The positive electrode current collector may be, for example, flat or sheet-like. The positive electrode current collector may be a collector with a three-dimensional mesh structure composed of foam metal, expanded metal, punched metal, or metal fiber felt. The positive electrode current collector is made of a material that is conductive and alkali-resistant. Examples of such materials include materials that are stable even at the reaction potential of the positive electrode (e.g., materials with a redox potential higher than the reaction potential of the positive electrode, or materials that form a protective coating such as an oxide film on the substrate surface in an alkaline aqueous solution to stabilize the substrate). Furthermore, at the positive electrode, a side reaction occurs in which the electrolyte decomposes, generating oxygen gas. Materials with a high oxygen overvoltage are preferred because they can suppress the progression of such side reactions. Specific examples of materials that can be used to form the positive electrode current collector include platinum; nickel (such as foamed nickel); and metal materials (such as copper, brass, and steel) plated with a metal such as nickel. Among these, a positive electrode current collector made of foamed nickel is preferably used. From the perspective of further improving high-rate discharge performance, it is preferable that at least the portion of the positive electrode current collector that supports the positive electrode material (positive electrode material support portion) be made of foamed nickel.

The positive electrode material is, for example, layered. That is, the positive electrode may have a positive electrode material layer. The positive electrode material layer may be formed on a positive electrode current collector. If the positive electrode material support portion of the positive electrode current collector has a three-dimensional mesh structure, the positive electrode material may be filled between the meshes of the current collector to form the positive electrode material layer. The positive electrode material contains a positive electrode active material containing nickel. Examples of positive electrode active materials include nickel oxyhydroxide (NiOOH) and nickel hydroxide. The positive electrode material contains, for example, nickel oxyhydroxide in a fully charged state and nickel hydroxide in an end-of-discharge state. The content of the positive electrode active material may be, for example, 50 to 95 mass% based on the total mass of the positive electrode material.

The positive electrode material may further contain additives other than the positive electrode active material. Examples of additives include binders, conductive agents, and expansion inhibitors. Examples of binders include hydrophilic or hydrophobic polymers. Specific examples include carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), sodium polyacrylate (SPA), and fluorine-based polymers (such as polytetrafluoroethylene (PTFE)). The binder content is, for example, 0.01 to 5 parts by mass per 100 parts by mass of the positive electrode active material. Examples of conductive agents include cobalt compounds (metallic cobalt, cobalt oxide, cobalt hydroxide, etc.). The conductive agent content is, for example, 1 to 20 parts by mass per 100 parts by mass of the positive electrode active material. Examples of expansion inhibitors include zinc oxide. The expansion inhibitor content is, for example, 0.01 to 5 parts by mass per 100 parts by mass of the positive electrode active material.

The electrolyte solution contains, for example, a solvent and an electrolyte. Examples of the solvent include water (e.g., ion-exchanged water). Examples of the electrolyte include basic compounds, such as alkali metal hydroxides such as potassium hydroxide (KOH), sodium hydroxide (NaOH), and lithium hydroxide (LiOH). The electrolyte solution may contain components other than the solvent and electrolyte, such as potassium phosphate, potassium fluoride, potassium carbonate, sodium phosphate, sodium fluoride, zinc oxide, antimony oxide, titanium dioxide, nonionic surfactants, and anionic surfactants.

The nickel-zinc battery described above can be obtained, for example, by a method that includes an assembly process in which components including electrodes are assembled to obtain a nickel-zinc battery. In the assembly process, for example, unformed positive electrodes and unformed negative electrodes are first alternately stacked with separators interposed between them, and the positive electrodes and negative electrodes are connected with straps to form an electrode group. Next, this electrode group is placed in a battery case, and a lid is attached to the top of the battery case to obtain an unformed nickel-zinc battery. Next, electrolyte is poured into the battery case of the unformed nickel-zinc battery, and the battery is left to stand for a certain period of time. Next, the battery is charged under specified conditions to form the nickel-zinc battery.

The above describes an example of a nickel-zinc battery (e.g., a nickel-zinc secondary battery) in which the positive electrode is a nickel electrode. However, the zinc battery may also be an air-zinc battery (e.g., an air-zinc secondary battery) in which the positive electrode is an air electrode, or a silver-zinc battery (e.g., a silver-zinc secondary battery) in which the positive electrode is a silver oxide electrode. The silver oxide electrode of a silver-zinc battery may be a known silver oxide electrode used in silver-zinc batteries. The silver oxide electrode contains, for example, silver(I) oxide. Furthermore, the air electrode of an air-zinc battery may be a known air electrode used in air-zinc batteries. The air electrode may contain, for example, an air electrode catalyst, an electron-conductive material, etc. The air electrode catalyst may be an air electrode catalyst that also functions as an electron-conductive material.

The air electrode catalyst can function as the positive electrode in an air-zinc battery, and various air electrode catalysts that can use oxygen as the positive electrode active material can be used. Examples of air electrode catalysts include carbon-based materials (such as graphite) with redox catalytic properties, metal materials (such as platinum and nickel) with redox catalytic properties, and inorganic oxide materials (such as perovskite-type oxides, manganese dioxide, nickel oxide, cobalt oxide, and spinel oxide) with redox catalytic properties. The shape of the air electrode catalyst is not particularly limited, but it can be, for example, particulate. The amount of air electrode catalyst used in the air electrode can be 5 to 70% by volume, 5 to 60% by volume, or 5 to 50% by volume of the total amount of the air electrode.

The electron-conductive material may be electrically conductive and allow electron conduction between the air electrode catalyst and the separator. Examples of electron-conductive materials include carbon blacks such as ketjen black, acetylene black, channel black, furnace black, lamp black, and thermal black; graphites such as natural graphite (e.g., flake graphite), artificial graphite, and expanded graphite; conductive fibers such as carbon fiber and metal fiber; metal powders such as copper, silver, nickel, and aluminum; organic electron-conductive materials such as polyphenylene derivatives; and mixtures of any of these. The electron-conductive material may be in particulate form or other shapes. It is preferable that the electron-conductive material be used in a form that provides a continuous phase through the thickness of the air electrode. For example, the electron-conductive material may be a porous material. The electron-conductive material may also be in the form of a mixture or composite with the air electrode catalyst, or, as described above, may be an air electrode catalyst that also functions as an electron-conductive material. The amount of electronically conductive material used in the air electrode may be 10 to 80% by volume, 15 to 80% by volume, or 20 to 80% by volume, relative to the total volume of the air electrode.

The effects achieved by the zinc battery negative electrode 1 according to the present embodiment described above will now be described. As described above, in the zinc battery negative electrode 1 according to the present embodiment, the current collector 2 includes a substrate 21 primarily containing carbon steel and a tin-plated film 22 covering at least a portion of the surface of the substrate 21. Experiments conducted by the inventors have shown that, although the electrical resistivity of carbon steel is greater than that of copper, when a tin-plated film is provided on the surface of carbon steel, the current collector for a zinc battery negative electrode can exhibit electrical performance equal to or superior to that of copper. Therefore, the zinc battery negative electrode 1 according to the present embodiment can provide a zinc battery negative electrode having a current collector primarily composed of a material that can be substituted for copper. In particular, carbon steel, such as cold-rolled steel sheet (e.g., SPCC), is widely distributed and abundant, making it less expensive than copper. Therefore, the zinc battery negative electrode 1 can be manufactured at lower cost than when the substrate is made of copper. Furthermore, by providing a tin-plated film 22 on the surface of the substrate 21, which primarily contains carbon steel, oxidation of the carbon steel can be prevented, extending the life of the current collector 2 and reducing the generation of hydrogen on the surface of the current collector 2.

The zinc battery negative electrode 1 of this embodiment includes a negative electrode material layer 3 adhered to a current collector 2. In this case, the current collector 2 may have multiple holes 21a that penetrate through the thickness direction and are filled with the negative electrode material layer 3. This allows the negative electrode material layer 3 to be firmly adhered to the current collector 2.

As mentioned above, the substrate 21 may be made of carbon steel. In other words, the substrate 21 may be made of only carbon steel. In this case, the effects of this embodiment can be more pronounced.

As mentioned above, the carbon content of the carbon steel may be 0.001% by mass or more and 0.15% by mass or less. In this case, a substrate 21 with good workability and relatively good electrical conductivity can be obtained.

As mentioned above, the substrate 21 may be a cold-rolled steel sheet. The electrical conductivity of cold-rolled steel sheet is relatively good among carbon steels, making it suitable as a material for the negative electrode of a zinc-cooled battery. In this case, the cold-rolled steel sheet may be SPCC. SPCC is one of the cold-rolled steel sheets with the highest distribution volume and is easy to obtain.

The present invention will be explained in more detail below using examples, but the present invention is not limited to the following examples.

(Example)
[Fabrication of negative electrode]
A tin-plated SPCC punched metal with a porosity of 50% was prepared as the negative electrode current collector. Next, predetermined amounts of zinc oxide, metallic zinc, surfactant, HEC, and ion-exchanged water were weighed and mixed, and the resulting mixture was stirred to prepare a negative electrode material paste. The mass ratio of the solids was adjusted to "zinc oxide: metallic zinc: HEC: surfactant = 84.5: 11.5: 3.5: 0.5." The moisture content of the negative electrode material paste was adjusted to 32.5% by mass based on the total mass of the negative electrode material paste. The negative electrode material paste was then applied to the negative electrode current collector and dried at 80 ° C. for 30 minutes. It was then pressure-molded using a roll press to obtain an unformed negative electrode having a negative electrode material layer.

[Preparation of Electrolyte Solution]
Potassium hydroxide (KOH) and lithium hydroxide (LiOH) were added to ion-exchanged water and mixed to prepare an electrolyte solution (potassium hydroxide concentration: 30 mass %, lithium hydroxide concentration: 1 mass %).

[Preparation of Positive Electrode]
A grid made of foamed nickel with a porosity of 95% was prepared and pressure-molded to obtain a positive electrode current collector. Next, a predetermined amount of cobalt-coated nickel hydroxide powder, metallic cobalt, cobalt hydroxide, yttrium oxide, CMC, PTFE, and ion-exchanged water were weighed and mixed, and the mixture was stirred to prepare a positive electrode material paste. The mass ratio of the solids was adjusted to "nickel hydroxide: metallic cobalt: yttrium oxide: cobalt hydroxide: CMC: PTFE = 88: 10.3: 1: 0.3: 0.3: 0.1". The moisture content of the positive electrode material paste was adjusted to 27.5% by mass based on the total mass of the positive electrode material paste. Next, the positive electrode material paste was applied to the positive electrode material support portion of the positive electrode current collector and then dried at 80 ° C for 30 minutes. The mixture was then pressure-molded using a roll press to obtain an unformed positive electrode having a positive electrode material layer.

[Preparing the separator]
For the separator, Celgard® 2500 was used as the microporous membrane, and VL100 (manufactured by Nippon Kodoshi Kogyo Co., Ltd.) was used as the nonwoven fabric. The microporous membrane was hydrophilized using the surfactant Triton®-X100 (manufactured by The Dow Chemical Company) before battery assembly. The hydrophilization was performed by immersing the microporous membrane in an aqueous solution containing 1% by mass of Triton-X100 for 24 hours, followed by drying at room temperature for 1 hour. The microporous membrane was then cut to a predetermined size, folded in half, and processed into a bag shape by heat welding the sides. One positive electrode (unformed positive electrode) and one negative electrode (unformed negative electrode) were housed in the bag-shaped microporous membrane. The nonwoven fabric used was cut to a predetermined size.

[Preparation of nickel-zinc battery]
Two positive electrodes, each housed in a microporous membrane bag, and three negative electrodes, each housed in a microporous membrane bag, were alternately stacked, a nonwoven fabric was sandwiched between the positive and negative electrodes, and plates of the same polarity were connected with a strap to produce an electrode assembly (electrode plate assembly). This electrode assembly was placed in a battery case, and a lid was attached to the top of the battery case to obtain an unformed nickel-zinc battery. Next, an electrolyte solution was poured into the battery case of the unformed nickel-zinc battery and left for 24 hours. The battery was then charged at 25 mA for 15 hours to produce a nickel-zinc battery with a nominal capacity of 350 mAh.

(Comparative Example)
A nickel-zinc battery was fabricated in the same manner as in the above example, except that a tin-plated copper punched metal having a porosity of 50% was used as the negative electrode current collector when fabricating the negative electrode.

<Discharge performance evaluation>
Using the nickel-zinc batteries of the Examples and Comparative Examples, the batteries were charged under constant voltage conditions of 25°C, an initial current of 350 mA (1 C), and a voltage of 1.9 V until the current decayed to 17.5 mA (0.05 C), and then discharged at a constant current of 17.5 mA (0.05 C) until the battery voltage reached 1.1 V. Low-rate discharge performance was determined by this. Furthermore, using the nickel-zinc batteries of the Examples and Comparative Examples, the batteries were charged under the same conditions as above, and then discharged at a constant current of 3500 mA (10.0 C) until the battery voltage reached 1.1 V. High-rate discharge performance was determined by this. The "C" above represents the relative magnitude of the current when the rated capacity is discharged at a constant current from a fully charged state. The "C" above refers to "discharge current value (A)/battery capacity (Ah)." For example, a current that can discharge the rated capacity in one hour is expressed as "1 C," and a current that can discharge the rated capacity in two hours is expressed as "0.5 C."

Figure 2(a) is a graph showing the discharge capacity (unit: Ah) for each discharge rate (0.05 C, 0.2 C, 1.0 C, 3.0 C, 5.0 C, and 10.0 C) for each of the nickel-zinc batteries of the Example and Comparative Example. Figure 2(b) is a graph showing the discharge capacity retention rate (percentage relative to 0.05 C, unit: %) for each discharge rate for each of the nickel-zinc batteries of the Example and Comparative Example. Figure 3 is a graph showing the relationship between the discharge capacity retention rate and the discharge rate. In Figure 3, graph G1 shows the Example, and graph G2 shows the Comparative Example.

As shown in Figures 2 and 3, when tin-plated SPCC was used as the current collector for the zinc battery negative electrode, electrical performance equivalent to or better than that achieved when tin-plated copper was used was achieved. It is expected that similar results would be achieved if carbon steel with a composition similar to or similar to SPCC were used. This example confirmed the effects of the above-described embodiment. The maximum temperature reached outside the battery case of the nickel-zinc battery at a discharge rate of 5.0 C was measured at 26.1°C for the example and 25.9°C for the comparative example. From these values, the maximum temperatures reached inside the battery were estimated to be 43.3°C and 42.9°C, respectively, confirming that the temperature rise was approximately the same in the example and comparative example. Furthermore, when the DC resistance was measured 10 seconds after the start of discharge at a 50% charge state, it was 2.39 (Ω·cm ² ) for the example and 2.35 (Ω·cm ² ) for the comparative example. This confirmed that the DC resistance was also approximately the same in the example and comparative example.

[Note]
The above-mentioned zinc battery negative electrode is a zinc battery negative electrode including a current collector, and the current collector has a substrate mainly containing carbon steel and a tin-plated film covering at least a portion of the surface of the substrate.
The zinc battery negative electrode may further include a negative electrode material layer fixed to a current collector, and the current collector may have a plurality of holes that penetrate through the thickness direction and are filled with the negative electrode material layer.
In the above-mentioned negative electrode for a zinc battery, the substrate of the current collector may be made of carbon steel.
In the zinc battery negative electrode, the carbon content of the carbon steel may be 0.001% by mass or more and 0.15% by mass or less.
In the above zinc battery negative electrode, the substrate may be a cold-rolled steel sheet, and in this case, the cold-rolled steel sheet may be SPCC.

1...zinc battery negative electrode, 2...current collector, 3...negative electrode material layer, 21...substrate, 21a...hole, 22...tin plating film.

Claims (2)

A positive electrode and
a negative electrode having a current collector and a negative electrode material layer fixed to the current collector ,
The current collector is
a substrate consisting solely of carbon steel;
a tin plating film covering at least a portion of the surface of the base material;
and
A nickel-zinc battery , wherein the carbon content of the carbon steel is 0.001% by mass or more and 0.15% by mass or less . 2. The nickel-zinc battery according to claim 1, wherein the thickness of the tin plating film is 0.1 μm or more and 5 μm or less.