Battery

Abstract

To improve productivity while suppressing the decline in discharge performance. [Solution] The battery 1 comprises a positive electrode can 11, a positive electrode 3 disposed inside the positive electrode can 11, a negative electrode 5 disposed in a negative electrode filling hole 19 formed in the positive electrode 3, and an electrolyte in which the positive electrode 3 and the negative electrode 5 are immersed. The weight per unit volume of the first portion 21 of the positive electrode 3, which is located on the side of the opening 16 of the positive electrode can 11 from the center 24, is greater than the weight per unit volume of the second portion 22 of the positive electrode 3 excluding the first portion 21.

Description

Technical Field

[0001] The technology of the present disclosure relates to batteries.

Background Art

[0002] Alkaline manganese dry batteries with a positive electrode containing electrolytic manganese dioxide MnO₂ are known (Patent Documents 1 and 2). In such alkaline manganese dry batteries, it is known that electrolytic manganese dioxide MnO₂ expands during discharge.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an alkaline manganese dry battery, the higher the density of the positive electrode, the greater the amount of electrolytic manganese dioxide MnO₂ contained in the positive electrode, and the better the discharge performance can be improved. However, when the density of the positive electrode is high, the positive electrode expands along with the expansion of electrolytic manganese dioxide MnO₂. If the expansion of the positive electrode is hindered, the reaction of electrolytic manganese dioxide MnO₂ is inhibited, and the discharge performance of the alkaline manganese dry battery may decrease. Also, in an alkaline manganese dry battery, when the density of the positive electrode is high, the rate at which the electrolyte penetrates into the positive electrode becomes slow, it takes time for the electrolyte to be absorbed, and the productivity may deteriorate.

[0005] The disclosed technology has been made in view of such points, and an object thereof is to provide a battery that suppresses a decrease in discharge performance and improves productivity.

Means for Solving the Problems

[0006] A battery according to one aspect of the present disclosure comprises a positive electrode casing, a positive electrode disposed inside the positive electrode casing, a negative electrode disposed in a negative electrode filling hole formed in the positive electrode, and an electrolyte in which the positive electrode and the negative electrode are immersed, wherein the weight per unit volume of a first portion of the positive electrode, which is located on the side of the opening of the positive electrode casing from the center of the positive electrode in the longitudinal direction of the positive electrode, is greater than the weight per unit volume of a second portion of the positive electrode excluding the first portion. [Effects of the Invention]

[0007] The disclosed battery can improve productivity while suppressing the degradation of discharge performance. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view showing a battery according to an embodiment. [Figure 2] Figure 2 is a perspective view showing the pellets. [Modes for carrying out the invention]

[0009] The battery according to the embodiments disclosed herein will be described below with reference to the drawings. However, the technology of this disclosure is not limited by the following description. Furthermore, the same reference numerals are used for identical components, and redundant descriptions are omitted.

[0010] [Battery of the embodiment] The battery 1 of this embodiment is an alkaline manganese dry cell and comprises a battery case 2, a positive electrode 3, a negative electrode 5, a current collector rod 6, and a separator 7, as shown in Figure 1. Figure 1 is a cross-sectional view showing the battery 1 of this embodiment. The battery case 2 comprises a positive electrode can 11 and a negative electrode terminal plate 12. The positive electrode can 11 is formed from a conductor, exemplified by metal. The positive electrode can 11 is formed in a bottomed cylindrical shape and comprises a side portion 14 and a bottom portion 15.

[0011] The side portion 14 is formed in a cylindrical shape and is positioned along the side of the cylinder. The bottom portion 15 is formed in a disc shape with irregularities and is positioned along one of the bottom surfaces of the cylinder. The bottom portion 15 is integrally formed with the side portion 14, with its edge connected to one end of the side portion 14. An opening 16 is formed in the positive electrode can 11. The opening 16 is formed in the part of the side portion 14 corresponding to the other bottom surface of the cylinder. The inside of the positive electrode can 11 is connected to the outside of the positive electrode can 11 through the opening 16. A positive electrode terminal portion 17 is formed in the center of the bottom portion 15. The bottom portion 15 is formed such that the positive electrode terminal portion 17 protrudes from the inside to the outside of the positive electrode can 11.

[0012] The negative electrode terminal plate 12 is formed from a conductor, exemplified by metal, and is generally disc-shaped. The negative electrode terminal plate 12 is positioned along the other bottom surface of the cylinder and covers the opening 16 of the positive electrode can 11. The internal space 18 surrounded by the positive electrode can 11 and the negative electrode terminal plate 12 is sealed by a sealing gasket (not shown) sandwiched between the edge of the negative electrode terminal plate 12 and the positive electrode can 11. The negative electrode terminal plate 12 is further fixed to the positive electrode can 11 by the sealing gasket sandwiched between the edge of the negative electrode terminal plate 12 and the positive electrode can 11, so as not to electrically contact the positive electrode can 11.

[0013] The positive electrode 3 contains electrolytic manganese dioxide (MnO2), graphite (C), an aqueous potassium hydroxide solution, and a binder. Electrolytic manganese dioxide (MnO2) is the positive electrode active material. The binder contains, for example, a polymer compound. The positive electrode 3 is formed from powders of electrolytic manganese dioxide (MnO2) and graphite (C) bonded together via the binder to form a solid. The positive electrode 3 is cylindrical, and a negative electrode filling hole (19) is formed inside the positive electrode 3, penetrating it. The positive electrode 3 is positioned in the internal space (18) of the battery case (2) such that its outer surface faces the side portion (14) of the positive electrode can (11). The positive electrode 3 is in close contact with the side portion (14) of the positive electrode can (11) so that it is electrically in contact with the positive electrode can (11).

[0014] The negative electrode 5 contains an aqueous potassium hydroxide solution, zinc oxide (ZnO), a gelling agent, and zinc powder (Zn). Examples of gelling agents include polyacrylic acid, polyacrylates, polyethylene glycol (PEG), polyethylene oxide (PEO), and carboxymethylcellulose (CMC). Examples of polyacrylates include sodium polyacrylate and potassium polyacrylate. The zinc powder (Zn) is formed from metallic zinc. Note that the zinc powder (Zn) may be substituted with other negative electrode active materials. Examples of other negative electrode active materials include zinc alloy powder formed from zinc-containing zinc alloys. The negative electrode 5 is formed in a gel-like state. The negative electrode 5 is located in the negative electrode filling hole 19 of the positive electrode 3 within the internal space 18 of the battery case 2.

[0015] The current collector rod 6 is formed from a conductor, exemplified by metal, and is shaped like a rod. One end of the current collector rod 6 is joined to the negative electrode terminal plate 12 so that the current collector rod 6 is fixed to the negative electrode terminal plate 12 and that the current collector rod 6 is in electrical contact with the negative electrode terminal plate 12. The current collector rod 6 is positioned in the internal space 18 along the central axis of the cylinder along which the side portion 14 is aligned. The current collector rod 6 is further embedded in the negative electrode 5 and is in electrical contact with the negative electrode 5.

[0016] The separator 7 is formed from a nonwoven fabric made of insulating fibers and is formed from a flexible sheet. Examples of insulating fibers include vinylon and pulp. The separator 7 is formed in a bottomed cylindrical shape and is positioned between the positive electrode 3 and the negative electrode 5 in the internal space 18, separating the positive electrode 3 and the negative electrode 5. The separator 7 is further positioned between the negative electrode 5 in the internal space 18 and the bottom portion 15 of the positive electrode can 11, separating the negative electrode 5 from the bottom portion 15. The negative electrode 5 is electrically insulated from the positive electrode 3 by the separator 7 separating the positive electrode 3 and the negative electrode 5. The negative electrode 5 is electrically insulated from the positive electrode can 11 by the separator 7 separating the negative electrode 5 from the bottom portion 15.

[0017] The battery 1 further includes an electrolyte (not shown). The electrolyte is formed from an aqueous potassium hydroxide solution containing potassium hydroxide KOH. The electrolyte is disposed in the internal space 18, permeates into the positive electrode 3 and the separator 7, and the positive electrode 3 and the negative electrode 5 are immersed in the electrolyte.

[0018] The positive electrode 3 is formed from a first portion 21 and a second portion 22. The first portion 21 is the portion of the positive electrode 3 that is disposed on the side of the opening 16 of the positive electrode can 11 from the center 24 in the longitudinal direction 23 of the positive electrode 3. The second portion 22 is the portion of the positive electrode 3 excluding the first portion 21, and is the portion of the positive electrode 3 that is disposed on the side of the bottom surface portion 15 of the positive electrode can 11 from the center 24. The positive electrode 3 is formed such that the density (weight per unit volume) of the first portion 21 is greater than the density of the second portion 22.

[0019] In the battery 1, a space 25 for positive electrode expansion is formed. The space 25 for positive electrode expansion is the space on the side of the opening 16 of the positive electrode 3 in the internal space 18, and is surrounded by the positive electrode 3, the negative electrode terminal plate 12, and the side surface portion 14 of the positive electrode can 11. That is, the end surface on the side of the opening 16 of the first portion 21 of the positive electrode 3 faces the space 25 for positive electrode expansion.

[0020] The positive electrode 3 is formed from a plurality of pellets 26. One pellet 27 among the plurality of pellets 26 is formed in a cylindrical shape as shown in FIG. 2. FIG. 2 is a perspective view showing the pellet 27. A through hole 28 is formed in the pellet 27. Other pellets different from the pellet 27 among the plurality of pellets 26 are also formed in a shape similar to the shape of the pellet 27.

[0021] As shown in FIG. 1, the positive electrode 3 is formed by arranging a plurality of pellets 26 in the longitudinal direction 23 of the positive electrode 3 such that a plurality of through holes 28 formed in each of the plurality of pellets 26 are connected. That is, the negative electrode filling hole 19 of the positive electrode 3 is formed from the plurality of through holes 28 formed in each of the plurality of pellets 26. The density of each of the plurality of pellets 26 is designed such that the density of the first portion 21 of the positive electrode 3 is greater than the density of the second portion 22.

[0022] [Battery manufacturing method] The battery manufacturing method for manufacturing the battery 1 includes a pellet manufacturing step and a battery assembly step. In the pellet manufacturing step, a positive electrode mixture is prepared. The positive electrode mixture is a powder and contains electrolytic manganese dioxide MnO2, graphite C, an aqueous potassium hydroxide solution, and a binder. The positive electrode mixture is subjected to molding and formed into pellets 27 having a predetermined density. In the molding process, a predetermined weight of the positive electrode mixture is poured into the inside of a molding die, and after a predetermined molding pressure is applied to the positive electrode mixture through the molding die, the pellets 27 are taken out of the molding die. The density of the pellets 27 is determined by the molding pressure and increases as the molding pressure increases. Other pellets are produced in the same manner as the pellets 27, and a plurality of pellets 26 are produced.

[0023] In the battery assembly, the positive electrode can 11 and the separator 7 are prepared. The plurality of pellets 26 are inserted into the inside of the positive electrode can 11 such that the outer peripheral surfaces of the plurality of pellets 26 contact the inner peripheral surface of the positive electrode can 11, and the positive electrode 3 is formed. That is, the plurality of pellets 26 are arranged such that when the positive electrode 3 is formed from the plurality of pellets 26, the density of the first portion 21 of the positive electrode 3 is greater than the density of the second portion 22. The separator 7 is inserted into the negative electrode filling hole 19 of the positive electrode 3 after the positive electrode 3 is formed and inserted into the positive electrode can 11.

[0024] In battery assembly, the electrolyte is prepared and the absorption time is set. After the separator 7 is inserted into the negative electrode filling hole 19 of the positive electrode 3, a predetermined amount of electrolyte is injected into the inside of the separator 7. The electrolyte seeps into the positive electrode 3 and the separator 7 over time as it is injected into the inside of the separator 7. The electrolyte must be completely absorbed by the positive electrode 3 and the separator 7 by the time the predetermined absorption time has elapsed after the electrolyte is injected into the inside of the separator 7. If any unabsorbed electrolyte remains inside the separator 7, it will cause contamination of the assembly equipment, so the absorption time is set so that the predetermined amount of electrolyte seeps into the positive electrode 3 and the separator 7.

[0025] In the assembly of the battery, the negative electrode 5, current collector rod 6, negative electrode terminal plate 12, and sealing gasket are further prepared. The negative electrode 5 is injected into the separator 7 after the electrolyte has been injected into the separator 7 and the absorption time has elapsed. After the negative electrode 5 is injected into the separator 7, the current collector rod 6, negative electrode terminal plate 12, and sealing gasket are attached to the positive electrode can 11 so that the current collector rod 6, which is joined to the negative electrode terminal plate 12, is embedded in the negative electrode 5, and so that the negative electrode terminal plate 12 and sealing gasket close the opening 16. By attaching the current collector rod 6, negative electrode terminal plate 12, and sealing gasket to the positive electrode can 11, the internal space 18 is sealed from the outside, and the battery 1 is manufactured.

[0026] Because the positive electrode 3 is formed from multiple pellets 26, the positive electrode 3 is easier to manufacture compared to other positive electrodes that are manufactured as a single molded body by molding. In other words, the battery 1 can easily manufacture a positive electrode 3 in which the density of the first part 21 is greater than the density of the second part 22, thereby improving the productivity of the battery manufacturing method.

[0027] The amount of gap formed inside the second portion 22 of the positive electrode 3 is greater than the amount of gap formed inside the first portion 21 because the density of the second portion 22 is lower than that of the first portion 21. Therefore, the amount of electrolyte that seeps into the second portion 22 is greater than the amount that seeps into the first portion 21, and the absorption rate of electrolyte that seeps into the second portion 22 is faster than the absorption rate of electrolyte that seeps into the first portion 21. As a result, the absorption time for a predetermined amount of electrolyte to seep into the positive electrode 3 is shorter than the absorption time for a predetermined amount of electrolyte to seep into the other positive electrode, which has a uniform density. As a result, the battery 1 can reduce the time spent in the electrolyte injection step of the battery manufacturing method, thereby improving the productivity of the battery manufacturing method.

[0028] Battery 1 discharges so that electricity flows to the load when the negative electrode terminal plate 12 and the positive electrode terminal portion 17 make electrical contact with the load. The electrolytic manganese dioxide (MnO2) contained in the positive electrode 3 undergoes a chemical reaction as battery 1 discharges, changing into manganese(III) oxide (Mn2O3) and expanding. The positive electrode 3 expands along with the electrolytic manganese dioxide (MnO2) during discharge. When the expansion of the positive electrode 3 is inhibited, the expansion of the electrolytic manganese dioxide (MnO2) is inhibited, and the chemical reaction of the electrolytic manganese dioxide (MnO2) may be inhibited. The discharge performance of the positive electrode 3 decreases when the chemical reaction of the electrolytic manganese dioxide (MnO2) is inhibited.

[0029] The expansion of the second portion 22 of the positive electrode 3 is inhibited because it is sandwiched between the first portion 21 and the bottom portion 15 of the positive electrode can 11. The amount of gap formed inside the second portion 22 is greater than the amount of gap formed inside the first portion 21, so even when the expansion of the second portion 22 is inhibited, the inhibition of the expansion of the manganese dioxide MnO2 contained in the second portion 22 is reduced, and the inhibition of the chemical reaction is reduced. The first portion 21 of the positive electrode 3 can expand significantly toward the opening 16 so that the positive electrode expansion space 25 narrows, because the end face of the first portion 21 on the side of the opening 16 faces the positive electrode expansion space 25. The electrolytic manganese dioxide MnO2 contained in the first portion 21 can undergo a chemical reaction without its expansion being inhibited because the first portion 21 can expand significantly during discharge. Furthermore, the amount of electrolytic manganese dioxide (MnO2) contained in the first part 21 is greater than the amount of electrolytic manganese dioxide (MnO2) contained in the second part 22, because the density of the first part 21 is greater than the density of the second part 22. Therefore, the battery 1 can suppress a decrease in discharge performance even when the expansion of the second part 22 of the positive electrode 3 is inhibited.

[0030] [Evaluation test of battery 1] To confirm the effectiveness of Battery 1 of the embodiment, multiple battery samples were prepared, and multiple evaluation tests were performed on each of the multiple battery samples. The multiple battery samples, as shown in Table 1, include the battery of Conventional Example 1, the battery of Conventional Example 2, the battery of Example 1, the battery of Example 2, the battery of Example 3, the battery of Example 4, the battery of Example 5, and the battery of Example 6. [Table 1] The multiple battery samples, as shown in Table 2, further include the battery of Conventional Example 3, the battery of Conventional Example 4, the battery of Example 7, and the battery of Example 8. [Table 2] The multiple battery samples further include the comparative battery and the battery of Example 9, as shown in Table 3. [Table 3]

[0031] Multiple battery samples are prepared under different preparation conditions. The preparation conditions are indicated by the densities of multiple positive electrode molded bodies corresponding to the multiple battery samples, the total weight of multiple positive electrode mixtures corresponding to the multiple battery samples, and the injection volume corresponding to the multiple battery samples. The positive electrode molded body density corresponding to a particular battery sample among the multiple positive electrode molded body densities indicates the number of multiple pellets 26 formed in the positive electrode 3 of that battery sample, the density of each of the multiple pellets 26, and the pellet density ratio. The pellet density ratio is a value calculated by dividing the maximum density of the multiple pellets 26 of that battery sample by the minimum density of the multiple pellets 26.

[0032] The multiple positive electrode molded body densities, as shown in Tables 1 to 2, indicate that the positive electrode 3 of the batteries in Conventional Examples 1 to 4 and the batteries in Examples 1 to 8 is formed from three pellets: a bottom pellet, a body pellet, and an opening pellet. The bottom pellet is the pellet located closest to the bottom portion 15 of the positive electrode can 11. The opening pellet is the pellet located closest to the opening 16 of the positive electrode can 11. The body pellet is the pellet located between the bottom pellet and the opening pellet.

[0033] The positive electrode molded body density corresponding to the battery in Conventional Example 1, among the multiple positive electrode molded body densities, shows that the density of the bottom pellet is 3.24 g / mL, the density of the body pellet is 3.24 g / mL, the density of the opening pellet is 3.24 g / mL, and the pellet density ratio is 1.00. The positive electrode molded body density corresponding to the battery in Conventional Example 2 shows that the density of the bottom pellet is 3.24 g / mL, the density of the body pellet is 3.24 g / mL, the density of the opening pellet is 3.24 g / mL, and the pellet density ratio is 1.00. In other words, in the positive electrodes of the batteries in Conventional Examples 1 and 2, the density of the first part 21 and the density of the second part 22 are equal.

[0034] The positive electrode molded body density for the battery of Example 1 shows that the density of the bottom pellet is 3.20 g / mL, the density of the body pellet is 3.24 g / mL, and the density of the opening pellet is 3.28 g / mL, resulting in a pellet density ratio of 1.03. The positive electrode molded body density for the battery of Example 2 shows that the density of the bottom pellet is 3.22 g / mL, the density of the body pellet is 3.22 g / mL, and the density of the opening pellet is 3.28 g / mL, resulting in a pellet density ratio of 1.02.

[0035] The positive electrode molded body density for the battery of Example 3 shows that the density of the bottom pellet is 3.16 g / mL, the density of the body pellet is 3.28 g / mL, and the density of the opening pellet is 3.28 g / mL, resulting in a pellet density ratio of 1.04. The positive electrode molded body density for the battery of Example 4 shows that the density of the bottom pellet is 3.23 g / mL, the density of the body pellet is 3.22 g / mL, and the density of the opening pellet is 3.27 g / mL, resulting in a pellet density ratio of 1.02.

[0036] The positive electrode molded body density for the battery in Example 5 shows that the density of the bottom pellet is 3.22 g / mL, the density of the body pellet is 3.26 g / mL, and the density of the opening pellet is 3.26 g / mL, resulting in a pellet density ratio of 1.01. The positive electrode molded body density for the battery in Example 6 shows that the density of the bottom pellet is 3.23 g / mL, the density of the body pellet is 3.24 g / mL, and the density of the opening pellet is 3.25 g / mL, resulting in a pellet density ratio of 1.01. In other words, in the positive electrodes of the batteries in Examples 1 to 5, the density of the first part 21 is greater than the density of the second part 22.

[0037] As shown in Table 2, the positive electrode molded body density for the battery in Conventional Example 3 is 3.20 g / mL for the bottom pellets, 3.20 g / mL for the body pellets, and 3.20 g / mL for the opening pellets, resulting in a pellet density ratio of 1.00. The positive electrode molded body density for the battery in Conventional Example 4 is 3.20 g / mL for the bottom pellets, 3.20 g / mL for the body pellets, and 3.20 g / mL for the opening pellets, resulting in a pellet density ratio of 1.00. In other words, in the positive electrodes of the batteries in Conventional Examples 3 and 4, the density of the first part 21 is equal to the density of the second part 22.

[0038] The positive electrode molded body density for the battery in Example 7 shows that the density of the bottom pellet is 3.16 g / mL, the density of the body pellet is 3.20 g / mL, and the density of the opening pellet is 3.24 g / mL, resulting in a pellet density ratio of 1.03. The positive electrode molded body density for the battery in Example 8 shows that the density of the bottom pellet is 3.17 g / mL, the density of the body pellet is 3.20 g / mL, and the density of the opening pellet is 3.23 g / mL, resulting in a pellet density ratio of 1.02. In other words, in the positive electrodes of the batteries in Examples 7 and 8, the density of the first part 21 is greater than the density of the second part 22.

[0039] The multiple positive electrode molded body densities further indicate that the positive electrode 3 of the comparative example battery and Example 9 is formed from four pellets: a bottom pellet, a body 1 pellet, a body 2 pellet, and an opening pellet, as shown in Table 3. The bottom pellet is the pellet located closest to the bottom portion 15 of the positive electrode can 11 among the four pellets. The opening pellet is the pellet located closest to the opening 16 of the positive electrode can 11 among the four pellets. The body 1 pellet and body 2 pellet are the two body pellets located between the bottom pellet and the opening pellet among the four pellets. The body 1 pellet is the pellet located between the bottom pellet and the body 2 pellet among the two body pellets. The body 2 pellet is the pellet located between the body 1 pellet and the opening pellet among the two body pellets.

[0040] The positive electrode molded body density corresponding to the comparative example battery shows that the density of the bottom pellet is 3.26 g / mL, the density of the body 1 pellet is 3.22 g / mL, the density of the body 2 pellet is 3.22 g / mL, and the density of the opening pellet is 3.26 g / mL, indicating a pellet density ratio of 1.01. In other words, in the comparative example battery, the density of the first part 21 is equal to the density of the second part 22. The positive electrode molded body density corresponding to the battery of Example 9 shows that the density of the bottom pellet is 3.26 g / mL, the density of the body 1 pellet is 3.19 g / mL, the density of the body 2 pellet is 3.25 g / mL, and the density of the opening pellet is 3.26 g / mL, indicating a pellet density ratio of 1.02. In other words, in the positive electrode of the battery of Example 9, the density of the first part 21 is greater than the density of the second part 22.

[0041] The total weight of positive electrode mixture corresponding to a particular battery sample among the total weights of multiple positive electrode mixtures indicates the weight of positive electrode 3 in that battery sample. The total weight of positive electrode mixture corresponding to the batteries of Conventional Examples 1 to 2 and the batteries of Examples 1 to 6, as shown in Table 1, indicates that the weight of positive electrode 3 in the batteries of Conventional Examples 1 to 2 and the batteries of Examples 1 to 6 is 11.25 g. The total weight of positive electrode mixture corresponding to the batteries of Conventional Examples 3 to 4 and the batteries of Examples 7 to 8, as shown in Table 2, indicates that the weight of positive electrode 3 in the batteries of Conventional Examples 3 to 4 and the batteries of Examples 7 to 8 is 11.10 g. The total weight of positive electrode mixture corresponding to the battery of the Comparative Example and the battery of Example 9, as shown in Table 3, indicates that the weight of positive electrode 3 in the battery of the Comparative Example and the battery of Example 9 is 11.25 g.

[0042] The amount of electrolyte injected corresponding to a particular battery sample among several injection amounts indicates the weight of the electrolyte in that battery sample. The amount of electrolyte injected corresponding to the battery in Conventional Example 1 indicates that the weight of the electrolyte in the battery in Conventional Example 1 is 1.40 g, as shown in Table 1. The amount of electrolyte injected corresponding to the battery in Conventional Example 2 and the batteries in Examples 1 to 6 indicates that the weight of the electrolyte in the battery in Conventional Example 2 and the batteries in Examples 1 to 6 is 1.45 g.

[0043] The amount of electrolyte injected corresponding to the battery in Conventional Example 3, as shown in Table 2, indicates that the weight of the electrolyte in the battery in Conventional Example 3 is 1.45 g. The amount of electrolyte injected corresponding to the battery in Conventional Example 4 and the batteries in Examples 7 to 8, as shown in Table 3, indicates that the weight of the electrolyte in the battery in Conventional Example 4 and the batteries in Examples 7 to 8 is 1.50 g. The amount of electrolyte injected corresponding to the battery in Comparative Example 9, as shown in Table 3, indicates that the weight of the electrolyte in the battery in Comparative Example 9 is 1.45 g.

[0044] The multiple battery samples were prepared similarly to each other, except that their preparation conditions differed. For example, each of the multiple battery samples was prepared so that its size was equal to that of a standard AA battery (LR6).

[0045] By performing multiple evaluation tests on each of the multiple battery samples, multiple liquid absorption rate evaluation results and multiple discharge performance evaluation results corresponding to the multiple battery samples are derived. The electrolyte absorption rate evaluation result corresponding to a particular battery sample among multiple electrolyte absorption rate evaluation results is derived by performing an electrolyte absorption rate evaluation test on that battery sample, and shows the amount absorbed at 20 minutes and the amount absorbed at 40 minutes. In the electrolyte absorption rate evaluation test, 20 minutes after a sufficient amount of electrolyte is injected into the inside of the separator 7 during the manufacturing process of one battery produced as the battery sample, the unabsorbed electrolyte that has not soaked into the positive electrode 3 and separator 7 for 20 minutes is removed from the inside of the separator 7. The amount absorbed at 20 minutes represents the amount absorbed, calculated by subtracting the weight of the unabsorbed electrolyte that has not soaked into the positive electrode 3 and separator 7 from the amount injected. In the electrolyte absorption rate evaluation test, further, 40 minutes after a sufficient amount of electrolyte is injected into the inside of the separator 7 during the manufacturing process of another battery produced as the battery sample, the unabsorbed electrolyte that has not soaked into the positive electrode 3 and separator 7 for 40 minutes is removed from the inside of the separator 7. The 40-minute absorption volume represents the amount absorbed, calculated by subtracting the weight of the unabsorbed electrolyte after 40 minutes from the injection volume. Among the multiple absorption rate evaluation results, the absorption rate evaluation result corresponding to a particular battery sample indicates that a larger 20-minute absorption volume indicates a faster absorption rate for that battery sample, and a larger 40-minute absorption volume indicates a faster absorption rate for that battery sample.

[0046] Of the multiple liquid absorption rate evaluation results, the liquid absorption rate evaluation results corresponding to the battery of Conventional Example 1, as shown in Table 1, indicate that the liquid absorption amount of the battery of Conventional Example 1 in 20 minutes is 1.40 g, and the liquid absorption amount of the battery of Conventional Example 1 in 40 minutes is 1.45 g. The liquid absorption rate evaluation results corresponding to the battery of Conventional Example 2 indicate that the liquid absorption amount of the battery of Conventional Example 2 in 20 minutes is 1.40 g, and the liquid absorption amount of the battery of Conventional Example 2 in 40 minutes is 1.45 g.

[0047] The liquid absorption rate evaluation results for the battery of Example 1 show that the liquid absorption amount of the battery of Example 1 in 20 minutes is 1.45 g, and the liquid absorption amount of the battery of Example 1 in 40 minutes is 1.48 g. The liquid absorption rate evaluation results for the battery of Example 2 show that the liquid absorption amount of the battery of Example 2 in 20 minutes is 1.43 g, and the liquid absorption amount of the battery of Example 2 in 40 minutes is 1.48 g.

[0048] The liquid absorption rate evaluation results for the battery of Example 3 show that the liquid absorption amount of the battery of Example 3 in 20 minutes is 1.44 g, and the liquid absorption amount of the battery of Example 3 in 40 minutes is 1.48 g. The liquid absorption rate evaluation results for the battery of Example 4 show that the liquid absorption amount of the battery of Example 4 in 20 minutes is 1.42 g, and the liquid absorption amount of the battery of Example 4 in 40 minutes is 1.47 g.

[0049] The liquid absorption rate evaluation results for the battery of Example 5 show that the liquid absorption amount of the battery of Example 5 in 20 minutes is 1.43 g, and the liquid absorption amount of the battery of Example 5 in 40 minutes is 1.46 g. The liquid absorption rate evaluation results for the battery of Example 6 show that the liquid absorption amount of the battery of Example 6 in 20 minutes is 1.41 g, and the liquid absorption amount of the battery of Example 6 in 40 minutes is 1.46 g.

[0050] The liquid absorption rate evaluation results for the battery in Conventional Example 3, as shown in Table 2, indicate that the liquid absorption amount for Conventional Example 3 in 20 minutes is 1.45 g, and the liquid absorption amount for Conventional Example 3 in 40 minutes is 1.50 g. The liquid absorption rate evaluation results for the battery in Conventional Example 4 indicate that the liquid absorption amount for Conventional Example 4 in 20 minutes is 1.45 g, and the liquid absorption amount for Conventional Example 4 in 40 minutes is 1.50 g.

[0051] The liquid absorption rate evaluation results for the battery of Example 7 show that the liquid absorption amount of the battery of Example 7 in 20 minutes is 1.50 g, and the liquid absorption amount of the battery of Example 7 in 40 minutes is 1.52 g. The liquid absorption rate evaluation results for the battery of Example 8 show that the liquid absorption amount of the battery of Example 8 in 20 minutes is 1.48 g, and the liquid absorption amount of the battery of Example 8 in 40 minutes is 1.50 g.

[0052] The liquid absorption rate evaluation results for the comparative example battery, as shown in Table 3, indicate that the liquid absorption amount for the comparative example battery in 20 minutes was 1.40 g, and the liquid absorption amount for the comparative example battery in 40 minutes was 1.45 g. The liquid absorption rate evaluation results for the battery of Example 9 indicate that the liquid absorption amount for the battery of Example 9 in 20 minutes was 1.42 g, and the liquid absorption amount for the battery of Example 9 in 40 minutes was 1.46 g.

[0053] Multiple liquid absorption rate evaluation results indicate that the liquid absorption rate of batteries in conventional examples 3-4 is faster than that of batteries in conventional examples 1-2. In other words, multiple liquid absorption rate evaluation results indicate that when the density of positive electrode 3 is uniform, the liquid absorption rate of batteries with a low density of positive electrode 3 is faster than that of batteries with a high density of positive electrode 3.

[0054] Multiple liquid absorption rate evaluation results indicate that the liquid absorption rates of the batteries in Examples 1-6 are faster than those of the batteries in Conventional Examples 1-2. Further, multiple liquid absorption rate evaluation results indicate that the liquid absorption rates of the batteries in Examples 7-8 are faster than those of the batteries in Conventional Examples 3-4. Further, multiple liquid absorption rate evaluation results indicate that the liquid absorption rate of the battery in Example 9 is faster than that of the comparative example battery. In other words, multiple liquid absorption rate evaluation results indicate that, when the total positive electrode weight is equal, the liquid absorption rate of battery 1, where the density of the first part 21 is greater than that of the second part 22, is faster than that of the battery where the densities of the first part 21 and the second part 22 are equal.

[0055] Multiple liquid absorption rate evaluation results indicate that the liquid absorption amount of batteries in Examples 1 and 3 over 20 minutes is greater than that of batteries in Examples 2, 4-6. Furthermore, multiple liquid absorption rate evaluation results indicate that the liquid absorption amount of batteries in Examples 1 and 3 over 40 minutes is not less than that of batteries in Examples 2, 4-6. Additionally, multiple liquid absorption rate evaluation results indicate that the liquid absorption rate of battery 7 is faster than that of battery 8. In other words, when the total positive electrode weight is equal, the liquid absorption rate of batteries with a pellet density ratio greater than 1.02 is faster than that of batteries with a pellet density ratio of 1.02 or less.

[0056] Multiple liquid absorption rate evaluation results indicate that the liquid absorption amount of batteries in Examples 1-5 over 20 minutes is greater than that of battery in Example 6 over 20 minutes. Furthermore, multiple liquid absorption rate evaluation results indicate that the liquid absorption amount of batteries in Examples 1-5 over 40 minutes is not less than that of battery in Example 6 over 20 minutes. In other words, multiple discharge performance evaluation results indicate that, when the total weight of the positive electrode and the amount of liquid injected are equal, the liquid absorption rate of batteries where the minimum density of the multiple pellets 26 is 3.22 g / mL or less is faster than the liquid absorption rate of batteries where the minimum density of the multiple pellets 26 is greater than 3.22 g / mL.

[0057] Multiple liquid absorption rate evaluation results indicate that the liquid absorption rate of batteries in Examples 1 and 3 over 20 minutes is greater than that of batteries in Examples 2, 4-6. Furthermore, multiple liquid absorption rate evaluation results indicate that the liquid absorption rate of batteries in Examples 1 and 3 over 40 minutes is not less than that of batteries in Examples 2, 4-6. In other words, multiple discharge performance evaluation results indicate that when the total positive electrode weight and the amount of liquid injected are equal, batteries with an opening pellet density of 3.24 g / mL or higher, and a minimum density of multiple pellets 26 of 3.22 g / mL or lower, have a faster liquid absorption rate than batteries that do not meet these criteria.

[0058] The discharge performance evaluation result corresponding to a particular battery sample among multiple discharge performance evaluation results is derived by performing a first discharge test and a second discharge test on that battery sample, and shows the first discharge time index and the second discharge time index. The first discharge test and the second discharge test are, for example, in accordance with the discharge tests specified in JIS standard JIS C8515 "Specifications for Individual Primary Batteries".

[0059] In the first discharge test performed on a battery sample, a daily discharge pattern is repeatedly executed on the battery sample in a 20°C atmosphere until the battery voltage reaches the cutoff voltage of 0.9V, and the first discharge time is derived. The daily discharge pattern consists of a 1-hour discharge period and a rest period. During the 1-hour discharge period, the battery sample is electrically connected to a load so that it discharges at 250mA. The rest period consists of the period of the daily discharge pattern excluding the 1-hour discharge period, and during the rest period, the battery sample is electrically isolated from the load so that it does not discharge. The first discharge time indicates the time the battery sample was discharged until its battery voltage reached the cutoff voltage of 0.9V. The first discharge time index is the value calculated by multiplying the value obtained by dividing the first discharge time of the battery sample by the first discharge time of the battery in Conventional Example 1 by 100.

[0060] In the second discharge test performed on a battery sample, a daily discharge pattern is repeatedly executed on the battery sample in a 20°C atmosphere until the battery voltage reaches the cutoff voltage of 0.8V, and the second discharge time is derived. The daily discharge pattern consists of a 1-hour discharge period and a rest period. During the 1-hour discharge period, the battery sample is electrically connected to a 3.9Ω load. The rest period consists of the period of the daily discharge pattern excluding the 1-hour discharge period, and during the rest period, the battery sample is electrically isolated from the load to prevent discharge. The second discharge time indicates the time the battery sample was discharged until its battery voltage reached the cutoff voltage of 0.8V. The second discharge time index is the value calculated by multiplying the value obtained by dividing the second discharge time of the battery sample by the second discharge time of the battery in Conventional Example 1 by 100. Multiple discharge test results indicate that a larger first discharge time index indicates better discharge performance for the battery sample, and a larger second discharge time index indicates better discharge performance for the battery sample.

[0061] As shown in Table 1, the discharge test results corresponding to the battery of Conventional Example 1 among the multiple discharge test results indicate that the first discharge time index of the battery of Conventional Example 1 is 100, and the second discharge time index of the battery of Conventional Example 1 is also 100. The discharge test results corresponding to the battery of Conventional Example 2 among the multiple discharge test results indicate that the first discharge time index of the battery of Conventional Example 2 is 103, and the second discharge time index of the battery of Conventional Example 2 is 104.

[0062] The discharge test results corresponding to the battery of Example 1 among the multiple discharge test results show that the first discharge time index of the battery of Example 1 is 104, and the second discharge time index of the battery of Example 1 is 106. The discharge test results corresponding to the battery of Example 2 among the multiple discharge test results show that the first discharge time index of the battery of Example 2 is 104, and the second discharge time index of the battery of Example 2 is 106.

[0063] The discharge test results corresponding to the battery of Example 3 among the multiple discharge test results show that the first discharge time index of the battery of Example 3 is 104 and the second discharge time index of the battery of Example 3 is 105. The discharge test results corresponding to the battery of Example 4 among the multiple discharge test results show that the first discharge time index of the battery of Example 4 is 103 and the second discharge time index of the battery of Example 4 is 105.

[0064] The discharge test results corresponding to the battery of Example 5 among the multiple discharge test results show that the first discharge time index of the battery of Example 5 is 103, and the second discharge time index of the battery of Example 5 is 105. The discharge test results corresponding to the battery of Example 6 among the multiple discharge test results show that the first discharge time index of the battery of Example 6 is 103, and the second discharge time index of the battery of Example 6 is 105.

[0065] As shown in Table 2, the discharge test results corresponding to the battery of Conventional Example 3 among the multiple discharge test results indicate that the first discharge time index of the battery of Conventional Example 3 is 98 and the second discharge time index of the battery of Conventional Example 3 is 102. The discharge test results corresponding to the battery of Conventional Example 4 among the multiple discharge test results indicate that the first discharge time index of the battery of Conventional Example 4 is 100 and the second discharge time index of the battery of Conventional Example 4 is 107.

[0066] The discharge test results corresponding to the battery of Example 7 among the multiple discharge test results show that the first discharge time index of the battery of Example 7 is 102, and the second discharge time index of the battery of Example 7 is 108. The discharge test results corresponding to the battery of Example 8 among the multiple discharge test results show that the first discharge time index of the battery of Example 8 is 101, and the second discharge time index of the battery of Example 8 is 107.

[0067] As shown in Table 3, the discharge test results corresponding to the comparative example battery among the multiple discharge test results indicate that the first discharge time index of the comparative example battery is 100 and the second discharge time index of the comparative example battery is 101. As shown in Table 3, the discharge test results corresponding to the example battery of Example 9 indicate that the first discharge time index of the example battery is 100 and the second discharge time index of the example battery is 101.

[0068] Multiple discharge performance evaluation results indicate that the discharge performance of the battery in Conventional Example 2 is better than that of the battery in Conventional Example 1. Furthermore, multiple discharge performance evaluation results indicate that the discharge performance of the battery in Conventional Example 4 is better than that of the battery in Conventional Example 3. In other words, multiple discharge performance evaluation results indicate that, when the total positive electrode weight is the same, the discharge performance of a battery with a larger electrolyte volume is better than that of a battery with a smaller electrolyte volume.

[0069] Multiple discharge performance evaluation results indicate that the discharge performance of the battery in Conventional Example 2 is better than that of the battery in Conventional Example 3. In other words, multiple discharge performance evaluation results indicate that, when the amount of electrolyte injected is the same, the discharge performance of a battery with a larger total positive electrode weight is better than that of a battery with a smaller total positive electrode weight.

[0070] Multiple discharge performance evaluation results indicate that the discharge performance of the batteries in Examples 1 to 6 is not inferior to that of the battery in Conventional Example 2. Furthermore, multiple discharge performance evaluation results indicate that the discharge performance of the batteries in Examples 7 to 8 is better than that of the battery in Conventional Example 4. Further, multiple discharge performance evaluation results indicate that the discharge performance of the battery in Example 9 is not inferior to that of the comparative example battery. In other words, even when the total positive electrode weight and the amount of electrolyte injected are equal, the discharge performance of a battery where the density of the first part 21 is greater than that of the second part 22 is not inferior to that of a battery where the density of the first part 21 and the density of the second part 22 are equal.

[0071] Multiple discharge performance evaluation results indicate that the discharge performance of the batteries in Examples 1 to 8 is better than that of the conventional batteries in Examples 1 to 4, the comparative example battery, and the battery in Example 9. In other words, multiple discharge performance evaluation results indicate that batteries in which the density of the opening pellets is greater than that of the bottom pellets have better discharge performance than batteries in which the density of the opening pellets is not greater than that of the bottom pellets.

[0072] Multiple discharge performance evaluation results indicate that the discharge performance of the batteries in Examples 1 to 6 is better than that of the battery in Example 9. In other words, multiple discharge performance evaluation results indicate that, when the total positive electrode weight is the same, batteries in which the density of the opening pellets is greater than that of the bottom pellets have better discharge performance than batteries in which the density of the opening pellets is not greater than that of the bottom pellets.

[0073] Multiple discharge performance evaluation results indicate that the discharge performance of the batteries in Examples 1 to 7 is better than that of the battery in Example 8 in terms of the first discharge time index. In other words, multiple discharge performance evaluation results indicate that the discharge performance of batteries with an opening pellet density of 3.24 g / mL or higher is not inferior to that of batteries with an opening pellet density of less than 3.24 g / mL.

[0074] Multiple discharge performance evaluation results indicate that the discharge performance of the battery in Example 7 is better than that of the battery in Example 8. In other words, multiple discharge performance evaluation results indicate that even when the total weight of the positive electrode and the amount of electrolyte injected are equal, the discharge performance of battery samples with an opening pellet density of 3.24 g / mL or higher is better than that of battery samples with an opening pellet density of less than 3.24 g / mL.

[0075] From the above, the results of multiple fluid absorption rate evaluations and multiple discharge performance evaluations indicate that batteries in which the density of the first part 21 is greater than the density of the second part 22 can improve productivity while suppressing a decrease in discharge performance, even when the total weight of the positive electrode and the amount of fluid injected are equal. Furthermore, the results of multiple fluid absorption rate evaluations and multiple discharge performance evaluations indicate that batteries in which the density of the opening pellets is greater than the density of the bottom pellets can further improve discharge performance while improving productivity, even when the total weight of the positive electrode and the amount of fluid injected are equal.

[0076] Multiple liquid absorption rate evaluation results and multiple discharge performance evaluation results further indicate that batteries with a pellet density ratio greater than 1.02 can further improve productivity while suppressing a decrease in discharge performance, even when the total positive electrode weight and the amount of liquid injected are equal. Multiple liquid absorption rate evaluation results and multiple discharge performance evaluation results further indicate that batteries with an opening pellet density of 3.24 g / mL or higher can further improve discharge performance while improving productivity, even when the total positive electrode weight and the amount of liquid injected are equal.

[0077] Multiple liquid absorption rate evaluation results and multiple discharge performance evaluation results further indicate that batteries in which the minimum density of multiple pellets 26 is 3.22 g / mL or less can further improve productivity while suppressing a decrease in discharge performance, even when the total weight of the positive electrode and the amount of liquid injected are equal. Multiple liquid absorption rate evaluation results and multiple discharge performance evaluation results further indicate that batteries in which the density of the opening pellet is 3.24 g / mL or more, and the minimum density of multiple pellets 26 is 3.22 g / mL or less, can further improve productivity while suppressing a decrease in discharge performance, even when the total weight of the positive electrode and the amount of liquid injected are equal.

[0078] [Effects of Battery 1 in the Embodiment] The battery 1 of this embodiment comprises a positive electrode casing 11, a positive electrode 3 disposed inside the positive electrode casing 11, a negative electrode 5 disposed in a negative electrode filling hole 19 formed in the positive electrode 3, and an electrolyte in which the positive electrode 3 and the negative electrode 5 are immersed. The density of the first portion 21 of the positive electrode 3, which is located closer to the opening 16 of the positive electrode casing 11 than the center 24, is greater than the density of the second portion 22 of the positive electrode 3 excluding the first portion 21. In this case, even when the total weight of the positive electrode and the amount of electrolyte injected are equal, the battery 1 can reduce the time required to soak the positive electrode 3 with the electrolyte while suppressing a decrease in discharge performance, thereby improving the productivity of the battery manufacturing method for producing the battery 1.

[0079] Furthermore, the positive electrode 3 of the battery 1 in this embodiment has a plurality of pellets 26 arranged in the longitudinal direction 23, and the density of the opening-side pellet, which is located closest to the opening 16 among the plurality of pellets 26, is greater than the density of at least one second pellet, which is different from the opening-side pellet among the plurality of pellets 26. In this case, the battery 1 can easily produce a positive electrode 3 in which the density of the first portion 21 is greater than the density of the second portion 22, and the productivity of the battery manufacturing method for producing the battery 1 can be improved.

[0080] Furthermore, in the embodiment of the battery 1, the density of the bottom-side pellets, which are located furthest from the opening 16 among the multiple pellets 26, is lower than the density of the opening-side pellets. In this case, the battery 1 can improve discharge performance while increasing productivity.

[0081] Furthermore, the density of the pellets on the opening side of the battery 1 in this embodiment is greater than 1.02 times the weight of the density of the second pellets. In this case, the battery 1 can further improve productivity while suppressing a decrease in discharge performance.

[0082] Furthermore, the density of the pellets on the opening side of the battery 1 in this embodiment is 3.24 g / mL or higher. In this case, the battery 1 can improve discharge performance while increasing productivity.

[0083] Furthermore, the density of at least one of the second pellets in the battery 1 of this embodiment is 3.22 g / mL or less. In this case, the battery 1 can further improve productivity while suppressing a decrease in discharge performance.

[0084] Furthermore, the density of the pellets on the opening side of the battery 1 in this embodiment is 3.24 g / mL or higher, and the density of at least one second pellet is less than 3.22 g / mL. In this case, the battery 1 can further improve productivity while suppressing a decrease in discharge performance.

[0085] By the way, in the embodiment described above, the positive electrode 3 of the battery has 3 or 4 pellets 26, but the number of pellets 26 may be 2 or 5 or more. Even in this case, the battery 1 can improve productivity while suppressing a decrease in discharge performance because the density of the first part 21 is greater than the density of the second part 22.

[0086] By the way, in the battery of the embodiment described above, the positive electrode 3 is formed from a plurality of pellets 26, but it may also be formed from a single molded body. Even in this case, the battery 1 can improve productivity while suppressing a decrease in discharge performance because the density of the first part 21 is greater than the density of the second part 22.

[0087] Although examples have been described above, the examples are not limited to those described above. Furthermore, the components described above include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the components described above can be combined as appropriate. Furthermore, at least one of various omissions, substitutions, and modifications of the components can be made without departing from the gist of the examples. [Explanation of Symbols]

[0088] 1:Battery 3: Positive electrode 5: Negative electrode 11: Positive electrode can 16: Opening 21: Part 1 22:Second part 23: Longitudinal direction 24:Center 26: Multiple pellets

Claims

1. Positive electrode can, The positive electrode is placed inside the positive electrode container, A negative electrode is disposed in a negative electrode filling hole formed in the positive electrode, The system comprises an electrolyte in which the positive electrode and the negative electrode are immersed, The weight per unit volume of the first portion of the positive electrode, which is positioned on the side of the opening of the positive electrode container from the center of the positive electrode in the longitudinal direction of the positive electrode, is greater than the weight per unit volume of the second portion of the positive electrode excluding the first portion. battery.

2. The positive electrode has a plurality of pellets arranged in the longitudinal direction, The weight per unit volume of the first pellet, which is positioned closest to the opening among the plurality of pellets, is greater than the weight per unit volume of at least one second pellet, which is different from the first pellet, among the plurality of pellets. The battery according to claim 1.

3. The weight per unit volume of the third pellet, which is positioned furthest from the opening among the plurality of pellets, is less than the weight per unit volume of the first pellet. The battery according to claim 2.

4. The weight per unit volume of the first pellet is greater than 1.02 times the weight per unit volume of the second pellet. The battery according to claim 2.

5. The weight per unit volume of the first pellet is 3.24 g / mL or more. The battery according to claim 2.

6. The weight per unit volume of at least one of the second pellets is 3.22 g / mL or less. The battery according to claim 2.

7. The weight per unit volume of the first pellet is 3.24 g / mL or more. The weight per unit volume of at least one of the second pellets is less than 3.22 g / mL. The battery according to claim 2.

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