Negative electrode can and manganese dry battery comprising same

Abstract

This manganese dry battery uses a negative electrode can that includes a battery can and a paste adhered to the inner peripheral surface of the battery can, wherein the paste contains starch particles, and the starch particles include first particles that each have a depression in the surface thereof.

Description

Negative electrode container and manganese dry cell equipped therewith Cross-reference of related applications

[0001] This disclosure claims priority to Provisional Application 63 / 728014, filed with the United States Patent and Trademark Office on 4 December 2024, and the entirety of the said patent application is incorporated herein by reference.

[0002] This disclosure relates to a negative electrode container and a manganese dry cell comprising the same.

[0003] In recent years, batteries have increasingly been used as power sources for high-rate devices, and improvements in the high-rate discharge characteristics of manganese dry cell batteries are desired.

[0004] Patent Document 1 proposes a manganese dry cell in which a separator coated with an adhesive is installed between a manganese dioxide positive electrode and a zinc negative electrode, characterized in that the adhesive is a mixture of starch with a torque of 1000 BU or more when held at 95°C using an 8% Brabender viscograph and starch with a torque of 1500 BU or less when held at 95°C using a 12% Brabender viscograph.

[0005] Patent Document 2 describes a manganese dry cell comprising a bottomed negative electrode zinc can, a positive electrode mixture and electrolyte filled in the negative electrode zinc can via a separator, wherein the separator consists of a wrapping paper and an adhesive adhering to the wrapping paper, the immersion rate of the wrapping paper is 500 seconds / 0.05 ml or less, and the basis weight of the wrapping paper is 55 g / m². ２ The present invention proposes a manganese dry cell in which the adhesive consists of starch, a nonionic surfactant, and a solvent, and the content of the nonionic surfactant in relation to the total weight of the starch, nonionic surfactant, and solvent is 1% by weight or more and 5% by weight or less.

[0006] Japanese Patent Publication No. 11-345602 Japanese Patent Publication No. 2004-063252

[0007] To improve the high-rate discharge characteristics of manganese dry cell batteries, sufficient moisture is required near the inner surface of the negative electrode casing. The adhesive plays a role in retaining moisture near the inner surface of the negative electrode casing. However, if the adhesive is only attached to the separator, the adhesive may not be able to move sufficiently near the inner surface of the negative electrode casing, which may limit the improvement of high-rate discharge characteristics. Furthermore, the starch contained in the adhesive of conventional separators has high swelling properties, resulting in insufficient storage characteristics for manganese dry cell batteries.

[0008] One aspect of the present disclosure relates to a negative electrode can for use in a manganese dry cell, wherein the negative electrode can comprises a bottomed cylindrical battery can and an adhesive adhering to the inner circumferential surface of the battery can, the adhesive comprising starch particles, and the starch particles comprising first particles having depressions on their surface.

[0009] Another aspect of this disclosure relates to a manganese dry cell comprising the negative electrode container described above, a positive electrode mixture housed in the negative electrode container, an electrolyte, and a separator disposed between the negative electrode container and the positive electrode mixture.

[0010] According to this disclosure, a manganese dry cell is provided that can achieve both excellent high-rate discharge characteristics and excellent storage characteristics.

[0011] This is a longitudinal cross-sectional view of a manganese dry cell according to one embodiment of the present disclosure. This is a schematic diagram showing the structure of the negative electrode casing according to one embodiment of the present disclosure. This is an SEM image of an example of the first particle. This is an SEM image of an example of the second particle.

[0012] While novel features of this disclosure are described in the attached claims, this disclosure, in conjunction with other purposes and features of this disclosure, will be better understood by the following detailed description accompanied by drawings, both in terms of its structure and content.

[0013] The embodiments of this disclosure will be described below with examples, but this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "greater than or equal to numerical value A and less than or equal to numerical value B". In the following description, when lower and upper limits of numerical values ​​relating to specific physical properties or conditions are given as examples, either of the given lower limits and either of the given upper limits can be arbitrarily combined, as long as the lower limit is not greater than or equal to the upper limit. When multiple materials are given as examples, one of them may be selected and used alone, or two or more may be used in combination.

[0014] Furthermore, this disclosure encompasses any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims. In other words, any combination of matters described in two or more claims, which may be arbitrarily selected from the multiple claims set forth in the attached claims, is possible, provided that no technical inconsistency arises.

[0015] The negative electrode can (hereinafter also referred to as "negative electrode can (N)") used in the manganese dry cell according to this disclosure comprises a bottomed cylindrical battery can and an adhesive adhering to the inner circumferential surface of the battery can. The adhesive contains starch particles. The starch particles include first particles having depressions (recesses) on their surface.

[0016] The first particle may have a flattened shape with a depression in the center. The first particle may have a flattened shape like a donut with a depression in the center, or it may have a shape like a red blood cell. The depression should be located on the surface of the particle as viewed from the depth direction of the depression, closer to the center of the surface than the outer edge, that is, roughly near the center of the first particle, and the center of gravity of the depression may be outside the center of gravity of the first particle. In the first particle, on the surface as viewed from the direction of the depression, the outer edge portion other than the central depression (peripheral portion) may not be depressed, or it may be depressed from the peripheral portion toward the center. If the peripheral portion is depressed, the slope of the surface of the central depression may be greater than the slope of the surface of the depression in the peripheral portion. The shape of the first particle may have a depression and a raised portion surrounding the depression (or a flattened shape). The shape of the first particle may have a depression and an annular raised portion surrounding the depression (or a flattened shape). The depressions may be formed on both sides of the first particle, or on one side. The depressions may be formed one on each side of the flattened first particle, or one on one side.

[0017] The manganese dry cell according to this disclosure comprises a negative electrode container (N), a positive electrode mixture housed in the negative electrode container (N), an electrolyte, and a separator disposed between the negative electrode container (N) and the positive electrode mixture.

[0018] The starch particles contained in the adhesive gradually swell and gelatinize (alpha-gelatinize) in the electrolyte, developing viscosity and liquid retention properties. The gelatinization of the starch particles allows the adhesive to draw the electrolyte impregnated in the positive electrode mixture to the interface between the negative electrode (N) and the separator, promoting the discharge reaction involving the negative electrode (N). Furthermore, the adhesive improves the adhesion between the separator and the negative electrode (N), reducing internal resistance and improving discharge performance. In other words, the adhesive improves the discharge performance (especially high-rate discharge performance) of manganese dry cell batteries from two perspectives. Moreover, the adhesive adhering to the inner surface of the battery can inhibits corrosion of the battery can. When the adhesive is directly adhering to the inner surface of the battery can, liquid retention near the inner surface is significantly improved, and the wettability of the inner surface by the electrolyte is enhanced. As a result, oxygen, which promotes corrosion, is less likely to come into contact with the inner surface of the battery can, resulting in the equation: 4Zn + 2O ２ +ZnCl ２ +4H ２ O → ZnCl ２ 4Zn(OH) ２ It is believed that the corrosion reaction of the battery can, as shown, will be suppressed.

[0019] However, if the starch particles swell excessively in the electrolyte or the binder deteriorates prematurely (beta-forming), the liquid retention near the inner surface of the battery can will not improve sufficiently, and the effects of improving the discharge performance of manganese dry cell batteries from the two aspects mentioned above will gradually decrease. In particular, at high temperatures above 45°C, the starch contained in conventional binders deteriorates easily, and the storage characteristics tend to deteriorate. Deterioration of storage characteristics leads to phenomena such as a decrease in high-rate discharge performance and a voltage drop from the expected voltage. In general, it can be said that improving high-rate discharge performance through alpha-forming and improving storage characteristics are mutually exclusive and difficult to achieve simultaneously.

[0020] In contrast, if the starch particles contained in the binder include first particles with depressions on their surface, it becomes possible to achieve both improved high-rate discharge performance and improved storage characteristics. This is thought to be because the depressions on the surface of the first particles increase the surface area of ​​the starch particles and allow a large amount of electrolyte to be held in the depressions. In other words, even when the gelatinization of the first particles has hardly progressed and the particle shape is generally maintained, the first particles have a high ability to retain electrolyte near the inner surface of the negative electrode can (N), and can exert an effect that improves the discharge performance (especially high-rate discharge performance) of the manganese dry cell. Furthermore, it is thought that the crystalline structure and molecular structure of the starch in the first particles differ from those of general starch particles, and because gelatinization progresses mildly, degradation is less likely to occur, and as a result, storage characteristics and corrosion resistance of the battery can are significantly improved.

[0021] The effects of the adhesive or first particles described above become even more pronounced when the adhesive is not only placed on the inner surface of the battery can, but also on at least the non-facing surface of the separator that does not face the negative electrode can (N) (i.e., the surface of the separator that faces the positive electrode mixture). This is because the electrolyte's liquid retention and adhesion at the interface between the separator and the positive electrode mixture are improved, promoting the movement of the electrolyte towards the inner surface of the negative electrode can (N), which greatly affects the high-rate discharge performance, storage characteristics, and corrosion resistance of the battery can.

[0022] The starch particles are derived from, for example, corn, but are not particularly limited. The first particle may be at least one selected from the group consisting of moist heat-treated starch particles (moist heat-treated starch) and enzyme-treated starch particles (enzyme-treated starch). Moist heat-treated or enzyme-treated starch particles have improved properties such as heat resistance and acid resistance due to changes in their molecular structure, and they become less prone to swelling in the electrolyte. Therefore, they contribute particularly to improving the storage characteristics of batteries.

[0023] The content of the first particles in the starch particles may be, for example, 10% by mass or more. When the starch particles contain 10% by mass or more of the first particles, it becomes easier to achieve both improved high-rate discharge characteristics and storage characteristics of manganese dry cell batteries. The content of the first particles in the starch particles is preferably, for example, 20% by mass to 80% by mass, and more preferably 40% by mass to 70% by mass.

[0024] The starch particles may include a second particle different from the first particle. When the thickener contains multiple types of starch particles, the gelatinization of the multiple types of starch particles proceeds gradually at different times over a long storage period, which is particularly advantageous for improving storage properties. The second particle, different from the first particle, is a particle with smaller surface depressions than the first particle (for example, the maximum depth of the depression is less than 10% of the maximum diameter of the starch particle) or a particle with no depressions on its surface, and may be a modified starch such as cross-linked starch or etherified starch.

[0025] The content of the second particle in the starch particles may be, for example, 20% by mass or more. When the starch particles contain the second particle at such a content, it becomes easier to further improve both the high-rate discharge characteristics and storage characteristics of the manganese dry cell.

[0026] The amount of adhesive adhering to the inner surface of the battery can (mass of the adhesive layer) is 5 g / m² per unit area of ​​the inner surface of the battery can. ２ More than 80g / m ２ The following is also acceptable. When the amount of adhesive adhering to the inner surface of the battery case is within this range, improvements in high-rate discharge characteristics and storage characteristics are promoted, and the corrosion resistance of the battery case is improved.

[0027] The adhesive may contain, in addition to starch particles, other components such as binders, thickeners, corrosion inhibitors, and surfactants. The binder primarily serves to adhere the starch particles to the substrate. The thickener primarily adjusts the viscosity of the aqueous slurry containing the dispersed adhesive. The corrosion inhibitor inhibits corrosion of the zinc-containing bottomed cylindrical negative electrode container. The surfactant contributes to the stability of the aqueous slurry containing the dispersed adhesive.

[0028] The binder is not particularly limited, but for example, polyvinyl alcohol, polyacrylamide, etc., can be used.

[0029] The thickening agent is not particularly limited, but examples include methylcellulose, tamarind seed gum, guar gum, and xanthan gum.

[0030] While not particularly limited, Bi compounds such as bismuth chloride and bismuth oxide can be used as anti-corrosion agents.

[0031] As the surfactant, there is no particular limitation, and for example, nonionic surfactants (e.g., tagitol) can be used.

[0032] As the separator, for example, paper materials (pulp materials) such as kraft paper are used. The thickness of the separator is, for example, 50 μm or more and 100 μm or less.

[0033] An aqueous slurry in which a paste is dispersed is applied to the inner peripheral surface of the battery can, and then the coating film is dried to obtain the negative electrode can (N). The method of applying the aqueous slurry to the inner peripheral surface of the battery can is not particularly limited, and for example, a spray coating method may be adopted. That is, the aqueous slurry may be atomized and discharged toward the inner peripheral surface of the battery can, and fine particles may be adhered to the inner peripheral surface of the battery can to form a coating film.

[0034] The separator may be, for example, a paper material having a basis weight (mass per unit area) of 40 g / m ２ or more and 80 g / m ２ or less.

[0035] When the thickness or basis weight of the separator is within the above range, the strength and liquid absorption of the separator are improved, so that not only the high-rate discharge characteristics and storage characteristics of the manganese dry battery are promoted, but also the reliability is improved.

[0036] Fig. 1 shows the structure of an example of a manganese dry battery according to an embodiment of the present disclosure. Fig. 1 is a front view of a part of the manganese dry battery 100 in cross section.

[0037] The negative electrode can (N) includes a bottomed cylindrical battery can 4 (zinc can) made of metallic zinc or a zinc alloy. After a separator 3 is installed on the inner peripheral surface of the battery can 4 and a bottom paper 13 is installed on the bottom surface, the positive electrode mixture 1 is housed in the battery can 4. A flange paper 9 is installed on the positive electrode mixture 1. The flange paper 9 is obtained by punching cardboard in a ring shape and has a center hole that fits into a carbon rod. A carbon rod 2 obtained by firing a carbon material and subjected to a water repellent treatment is inserted into the central portion of the positive electrode mixture 1.

[0038] The sealing body 5 that seals the opening of the battery can 4 is made of resin and has a central hole into which the carbon rod 2 is inserted. After bending the open end of the battery can 4 inward, the sealing body 5 is fitted onto the carbon rod 2.

[0039] On the outer periphery of the battery can 4, a resin tube 8 having heat shrinkability for ensuring insulation is arranged, and the upper end portion of the resin tube 8 covers the upper surface of the outer peripheral portion of the sealing body 5. The lower end portion of the resin tube 8 covers the flange portion of the negative electrode terminal plate 6 made of tinplate disposed on the bottom surface of the battery can 4 via a seal ring 7. The seal ring 7 is formed by punching out a paperboard impregnated with paraffin in a ring shape.

[0040] A positive electrode terminal plate 11 made of tinplate is attached to the top of the carbon rod 2. The positive electrode terminal plate 11 has a cap-shaped portion for fitting the carbon rod and a flat flange portion. An insulating ring 12 made of resin is arranged outside the flat flange portion.

[0041] The metal outer can 10 made of a cylindrical tinplate is disposed outside the resin tube 8, and its upper end portion and lower end portion are bent inward to clamp the insulating ring 12 and the end portion of the resin tube 8, respectively.

[0042] In the negative can (N), the above-described paste is applied to the inner peripheral surface of the battery can 4. Fig. 2 schematically shows the structure of the negative can (N). In the illustrated example, a paste layer 32 is formed on the inner peripheral surface of the battery can 4. The paste layer 32 is formed by applying a slurry in which a paste containing starch particles 301, a Bi compound 302, a binder 303, etc. is dispersed to the inner peripheral surface of the battery can 4 and drying it. The paste layer 32 before filling the positive electrode mixture 1 is in a dry state, and the paste adheres to the inner peripheral surface of the battery can 4 mainly by the action of the binder 303. In the assembled battery, the electrolyte penetrates into the paste, and the starch particles 301 in the paste hold the electrolyte, achieving a desired effect. In the illustrated example, the paste layer 32 is also formed on at least the surface of the base material 31 of the separator 3 on the positive electrode mixture 1 side.

[0043] The starch particles preferably include first and second particles. Figure 3 is an SEM image of an example of first particles, and Figure 4 is an SEM image of an example of second particles. The first particles have a flattened, donut-like shape with depressions (recesses) on their surface and a center that does not penetrate. On the other hand, the second particles do not have such depressions. The second particles may be, for example, general modified starch.

[0044] The manganese dry cell according to this disclosure is manufactured by, for example, the following manufacturing process: Step A: A slurry containing the aforementioned adhesive is applied to the inner surface of the battery can, and then dried to form an adhesive layer on the inner surface of the battery can, thereby obtaining the negative electrode can (N).

[0045] Step B: The separator is positioned so as to face the inner surface of the battery can (i.e., the negative electrode can) on which the adhesive layer has been formed.

[0046] Step C: A positive electrode mixture containing an electrolyte is filled into the negative electrode container via a separator. The positive electrode mixture may include, for example, a mixture of manganese dioxide as the positive electrode active material, acetylene black as the conductive material, and an electrolyte. As the electrolyte, for example, an aqueous zinc chloride solution may be used.

[0047] Step D: A carbon rod is inserted into the positive electrode mixture filled in the negative electrode container. At this time, the carbon rod pushes the positive electrode mixture outward, causing the electrolyte in the positive electrode mixture to seep out towards the separator, permeate the separator, and reach the adhesive layer of the negative electrode container. Subsequently, the gelatinization of the starch particles gradually progresses.

[0048] (Note) The following technologies are disclosed by the above description. (Technology 1) A negative electrode can for use in a manganese dry cell, wherein the negative electrode can comprises a battery can and an adhesive adhering to the inner circumferential surface of the battery can, wherein the adhesive comprises starch particles, and the starch particles comprises first particles having depressions on their surface. (Technology 2) The negative electrode can according to Technology 1, wherein the first particles are at least one selected from the group consisting of moist heat-treated starch particles and enzyme-treated starch particles. (Technology 3) The negative electrode can according to Technology 1 or 2, wherein the content of the first particles in the starch particles is 10% by mass or more. (Technology 4) The negative electrode can according to any one of Technology 1 to 3, wherein the starch particles comprises second particles different from the first particles, and the second particles have small depressions on their surface or no depressions on their surface. (Technical 5) The amount of adhesive adhering to the inner surface of the battery can is 5 g / m² per unit area of ​​the inner surface of the battery can. ２ More than 80g / m ２ The negative electrode container according to any one of the following technologies 1 to 4: (Technology 6) The negative electrode container according to technology 1, wherein the battery container contains zinc. (Technology 7) The separator according to any one of the following technologies 1 to 6, wherein the thickness of the substrate is 50 μm or more and 100 μm or less. (Technology 8) The substrate has a basis weight of 40 g / m². ２ 80g / m or more ２ A separator according to any one of the following paper materials, described in Technology 1 to 7. (Technology 9) A manganese dry cell comprising: a negative electrode can according to Technology 1; a positive electrode mixture housed in the negative electrode can; an electrolyte; and a separator disposed between the negative electrode can and the positive electrode mixture. (Technology 10) The manganese dry cell according to Technology 9, wherein the adhesive is attached to at least the surface of the separator facing the positive electrode mixture.

[0049] The embodiments of this disclosure will be described in detail below, but the present invention is not limited to the following embodiments.

[0050] Example 1: A AA-size manganese dry cell A1 was manufactured using a battery casing made of zinc alloy and a negative electrode casing (N) having an adhesive layer attached to the inner surface of the battery casing.

[0051] The separator interposed between the positive electrode mixture and the negative electrode can is made of kraft paper (base material), and the kraft paper has a thickness of 70 μm.

[0052] The positive electrode mixture used was a mixture of manganese dioxide, acetylene black, and an electrolyte solution consisting of a 30% by weight aqueous solution of zinc chloride (zinc chloride concentration 2.2 mol / L) in a weight ratio of 50:10:40.

[0053] Here, a slurry was prepared by dividing 38 parts by weight of adhesive material with the following composition into 62 parts by weight of water. The slurry was spray-applied to the inner surface of the battery can and allowed to dry, thereby forming an adhesive layer. The amount of adhesive layer adhering to the inner surface of the battery can was 20 g / m² per unit area of ​​the inner surface of the battery can. ２ That's what I decided.

[0054] Component 1: 50 parts by mass of starch particles (a mixture of 10 parts by mass of first particles (moist heat-treated starch particles) and 90 parts by mass of second particles (cross-linked starch)) Component 2: 5 parts by mass of polyvinyl alcohol, 40 parts by mass of polyacrylamide Component 3: 3 parts by mass of xanthan gum Component 4: 0.5 parts by mass of bismuth chloride Component 5: 1.5 parts by mass of nonionic surfactant

[0055] <Comparative Example 1> A manganese dry cell B1 was prepared in the same manner as in Example 1, except that starch particles containing 100% of the second particle (cross-linked starch) and not the first particle were used as component 1.

[0056] [Evaluation 1] The discharge duration was measured during high-rate discharge initially (3 days after battery fabrication) and after 3 months of storage at 45°C. Specifically, five of each battery were prepared, and they were continuously discharged at 3.9Ω. The discharge duration until the cutoff voltage of 0.9V was measured. The average discharge duration of the five batteries was then calculated. This evaluation was carried out in an atmosphere of 20°C. The evaluation results are shown in Table 1. The evaluation results are relative values ​​with the initial discharge duration of battery B1 set to 100.

[0057]

[0058] [Evaluation 2] The corrosion resistance of the negative electrode can was evaluated based on the mass loss of the battery can. Specifically, the mass of the raw battery can and the mass of the battery can obtained by removing the adhesive and corrosion products adhering to the inner surface of a negative electrode can removed from a battery stored at 45°C for 6 months were measured. The mass loss of the battery can was then calculated using the following formula (A). The mass of the raw battery can and the mass of the battery can removed from a battery stored at 45°C for 6 months are both average values ​​of 10 battery cans. The evaluation results are shown in Table 2.

[0059] Formula (A): Mass loss of battery casing = (Average mass of raw battery casings) - (Average mass of battery casings removed from batteries after storage at 45°C for 6 months)

[0060]

[0061] The manganese dry cell battery described herein is useful as a power source for high-rate devices and the like.

[0062] While this disclosure describes preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which this disclosure pertains by reading the above disclosure. Accordingly, the attached claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of this disclosure.

[0063] 1. Positive electrode mixture 2. Carbon rod 3. Separator 4. Battery casing 5. Sealing body 6. Negative electrode terminal 7. Seal ring 8. Resin tube 9. Flange paper 10. Metal casing 11. Positive electrode terminal plate 12. Insulating ring 13. Bottom paper 100 Manganese dry cell

Claims

1. A negative electrode can for use in a manganese dry cell, wherein the negative electrode can comprises a bottomed cylindrical battery can and an adhesive adhering to the inner circumferential surface of the battery can, wherein the adhesive contains starch particles, and the starch particles include first particles having depressions on their surface.

2. The negative electrode can according to claim 1, wherein the first particle is at least one selected from the group consisting of moist heat-treated starch particles and enzyme-treated starch particles.

3. The negative electrode can according to claim 1, wherein the content of the first particle in the starch particles is 10% by mass or more.

4. The negative electrode can according to claim 1, wherein the starch particles include second particles different from the first particles, and the second particles have smaller surface depressions than the first particles or have no surface depressions.

5. The amount of adhesive adhering to the inner surface of the battery can is 5 g / m² per unit area of ​​the inner surface of the battery can. ２ More than 80g / m ２ The negative electrode can according to claim 1, which is as follows:

6. The negative electrode can according to claim 1, wherein the battery can contains zinc.

7. A manganese dry cell comprising: a negative electrode container according to claim 1; a positive electrode mixture housed in the negative electrode container; an electrolyte; and a separator disposed between the negative electrode container and the positive electrode mixture.

8. The manganese dry cell according to claim 7, wherein the adhesive is attached to at least the surface of the separator facing the positive electrode mixture.

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