Battery manufacturing method and battery

Abstract

To suppress gas generation inside a battery.SOLUTION: A battery manufacturing method is a method for manufacturing batteries. The method includes: filtering a zinc oxide-dissolving electrolyte containing potassium hydroxide KOH and zinc oxide ZnO dissolved therein (step S3); cooling an electrolyte after the removal of impurities so that solid zinc oxide ZnO precipitates in the electrolyte after the removal of impurities which is generated by filtering the zinc oxide-dissolving electrolyte, and diluting the cooled electrolyte with water (step S4, step S5); and fabricating a gel-like negative electrode so that the gel-like negative electrode further contains a zinc oxide deposition electrolyte which is generated by cooling the electrolyte after the removal of impurities and diluting the cooled electrolyte with water (step S6, step S7).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a battery manufacturing method and a battery. [Background technology]

[0002] Alkaline manganese dry batteries in which zinc oxide ZnO is added to the negative electrode are known (Patent Documents 1 to 4). Such alkaline manganese dry batteries can suppress gas generation inside the battery when charged due to misuse, and can suppress leakage of the electrolyte or gas to the outside of the positive electrode can. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-156158 [Patent Document 2] International Publication No. 2010 / 140295 [Patent Document 3] Japanese Patent Application Publication No. 30-31328 [Patent Document 4] Japanese Patent Application Publication No. 2018-142516 Summary of the Invention [Problem to be solved by the invention]

[0004] The zinc oxide raw material used to make the negative electrode may contain iron powder (Fe) as an impurity, and in this case, the iron powder (Fe) may be mixed into the negative electrode. When iron powder (Fe) is mixed into the negative electrode of an alkaline manganese dry battery, gas may be generated inside the battery even when the battery is not being charged, which may cause leakage.

[0005] The disclosed technology has been made in view of the above points, and aims to provide a battery manufacturing method and a battery that suppresses gas generation inside the battery. [Means for solving the problem]

[0006] A battery manufacturing method according to one aspect of the present disclosure is a battery manufacturing method for manufacturing a battery including a positive electrode, a negative electrode containing zinc, and an electrolyte solution in which the positive electrode and the negative electrode are immersed, the method including removing solid substances from a zinc oxide-dissolved electrolyte solution in which potassium hydroxide and zinc oxide are dissolved; treating the impurity-removed electrolyte solution produced by removing the substances from the zinc oxide-dissolved electrolyte solution so that solid zinc oxide precipitates in the impurity-removed electrolyte solution; and fabricating the negative electrode so that the negative electrode further contains the zinc oxide-precipitated electrolyte solution produced by treating the impurity-removed electrolyte solution. [Effects of the Invention]

[0007] The disclosed battery manufacturing method and battery can suppress gas generation inside the battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a battery according to an embodiment. [Figure 2] FIG. 2 is a flowchart showing the negative electrode fabrication process in the battery manufacturing method of the embodiment. [Figure 3] FIG. 3 is a flowchart showing the negative electrode fabrication process in the battery manufacturing method of Comparative Example 1. [Figure 4] FIG. 4 is a circuit diagram showing the electrical circuit used in the 4-series 1-reverse test. [Figure 5] FIG. 5 is a flowchart showing the negative electrode fabrication process in the battery manufacturing method of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a battery manufacturing method and a battery according to embodiments disclosed herein will be described with reference to the drawings. Note that the following description does not limit the technology of the present disclosure. In addition, in the following description, the same components are given the same reference numerals, and duplicated descriptions will be omitted.

[0010] [Battery of the embodiment] The battery 1 of this embodiment is an alkaline manganese dry battery, and as shown in FIG. 1, includes a battery case 2, a positive electrode 3, a gelled negative electrode 5 (negative electrode), a current collector 6, and a separator 7. FIG. 1 is a cross-sectional view showing the battery 1 of this embodiment. The battery case 2 includes a positive electrode can 11, a negative electrode terminal plate 12, and a sealing gasket 14. The positive electrode can 11 is made of a conductor, such as a metal. The positive electrode can 11 is formed in a cylindrical shape with a bottom, and includes a side portion 15 and a bottom portion 16.

[0011] The side portion 15 is cylindrical and disposed along the side of the cylinder. The bottom portion 16 is disc-shaped with irregularities and disposed along one bottom surface of the cylinder. The edge of the bottom portion 16 is connected to one end of the side portion 15, and the bottom portion 16 is formed integrally with the side portion 15. The positive electrode can 11 has an opening 17. The opening 17 is formed in a portion of the side portion 15 that corresponds to the other bottom surface of the cylinder. The interior of the positive electrode can 11 is connected to the exterior of the positive electrode can 11 via the opening 17. A positive electrode terminal portion 18 is formed in the center of the bottom portion 16. The bottom portion 16 is formed so that the positive electrode terminal portion 18 protrudes from the inside of the positive electrode can 11 toward the outside.

[0012] A beading portion 21 and a curled portion 22 are formed on the side surface portion 15 of the positive electrode can 11. The beading portion 21 is formed near the open end 23 of the side surface portion 15 on the side where the opening 17 is formed. The beading portion 21 is formed so as to protrude from the inner surface of the side surface portion 15 toward the inside of the positive electrode can 11, i.e., so that the inner diameter of the portion of the side surface portion 15 where the beading portion 21 is formed is smaller than the inner diameter of the remaining portion. The curled portion 22 is formed between the beading portion 21 and the open end 23. The curled portion 22 is formed so that the inner diameter of the side surface portion 15 decreases as it approaches the open end 23.

[0013] The negative electrode terminal plate 12 is made of a conductor such as a metal and is formed in a generally disk shape. The negative electrode terminal plate 12 is arranged along the other bottom surface of the cylinder and closes the opening 17 of the positive electrode can 11. Inside the battery case 2, the negative electrode terminal plate 12 closes the opening 17, thereby forming an internal space 25 surrounded by the positive electrode can 11 and the negative electrode terminal plate 12.

[0014] The sealing gasket 14 is made of an insulating material such as a resin and is formed in a generally ring shape. The sealing gasket 14 is placed in the opening 17 of the positive electrode can 11 and surrounds the edge of the negative electrode terminal plate 12. The sealing gasket 14 is sandwiched between the edge of the negative electrode terminal plate 12 and a side surface portion 15 of the positive electrode can 11, and closes the gap formed between the edge of the negative electrode terminal plate 12 and the positive electrode can 11.

[0015] The sealing gasket 14 is fixed to the positive electrode can 11 by contacting the beading portion 21, preventing the sealing gasket 14 from moving toward the bottom portion 16 of the positive electrode can 11. The sealing gasket 14 is further fixed to the positive electrode can 11 by contacting the curled portion 22, preventing the sealing gasket 14 from slipping out of the inside of the positive electrode can 11. The negative electrode terminal plate 12 is fixed to the sealing gasket 14 by having a portion of the sealing gasket 14 sandwiched between the edge of the negative electrode terminal plate 12 and the side portion 15 of the positive electrode can 11, and is fixed to the positive electrode can 11 via the sealing gasket 14. The negative electrode terminal plate 12 is electrically insulated from the positive electrode can 11 via the sealing gasket 14 by having the sealing gasket 14 sandwiched between the edge of the negative electrode terminal plate 12 and the positive electrode can 11. The sealing gasket 14 is further formed with a pressure release valve 27. The pressure release valve 27 is a portion of the sealing gasket 14 that is thin in thickness.

[0016] The positive electrode 3 contains electrolytic manganese dioxide (MnO2), graphite (C), a potassium hydroxide aqueous solution, and a binder. The electrolytic manganese dioxide (MnO2) is a positive electrode active material. The binder contains, for example, a polymer compound. The positive electrode 3 is formed by powders of electrolytic manganese dioxide (MnO2) and graphite (C) being bonded together via the binder to form a solid. The positive electrode 3 includes three pellets. Each of the three pellets is formed in a cylindrical shape. The three pellets are arranged in the positive electrode 3 so that three through-holes formed in each pellet are connected. That is, the positive electrode 3 is formed in a cylindrical shape, and a negative electrode filling hole 28 penetrating the positive electrode 3 is formed inside the positive electrode 3. The positive electrode 3 is disposed in the internal space 25 of the battery case 2 such that the outer surface of the positive electrode 3 faces the side surface portion 15 of the positive electrode can 11. The positive electrode 3 is in intimate contact with a side portion 15 of the positive electrode can 11 so that the positive electrode 3 is in electrical contact with the positive electrode can 11 .

[0017] The gelled negative electrode 5 contains a potassium hydroxide aqueous solution, zinc oxide ZnO, a gelling agent, and zinc powder Zn. The gelled negative electrode 5 contains more zinc oxide ZnO than the solubility of zinc oxide ZnO in the potassium hydroxide aqueous solution. That is, some of the zinc oxide ZnO dissolves in the potassium hydroxide aqueous solution, while the other part remains solid, resulting in the precipitation of the zinc oxide ZnO that was dissolved in the potassium hydroxide aqueous solution. Examples of gelling agents include polyacrylic acid, polyacrylates, polyethylene glycol (PEG), polyethylene oxide (PEO), and carboxymethyl cellulose (CMC). Examples of polyacrylates include sodium polyacrylate and potassium polyacrylate. The zinc powder Zn is made from metallic zinc. Note that the zinc powder Zn may be replaced with other negative electrode active materials. Examples of other negative electrode active materials include zinc alloy powder made from a zinc alloy containing zinc. Furthermore, the value calculated by dividing the amount of iron powder (Fe) contained in the gelled negative electrode 5 by the amount of solid zinc oxide (ZnO) contained in the gelled negative electrode 5 is smaller than the value calculated by dividing the amount of iron powder (Fe) contained as an impurity in the zinc oxide raw material used to prepare the gelled negative electrode 5 by the amount of zinc oxide (ZnO) contained in the zinc oxide raw material. The gelled negative electrode 5 is formed in a gel state. The gelled negative electrode 5 is disposed in the negative electrode filling hole 28 of the positive electrode 3 within the internal space 25 of the battery case 2.

[0018] The current collecting rod 6 is formed from a conductor such as a metal and is formed in a rod shape. One end of the current collecting rod 6 is joined to the negative electrode terminal plate 12 so that the current collecting rod 6 is fixed to the negative electrode terminal plate 12 and so that the current collecting rod 6 is in electrical contact with the negative electrode terminal plate 12. The current collecting rod 6 further penetrates a sealing gasket 14, is fixed to the sealing gasket 14, and is fixed to the positive electrode can 11 via the sealing gasket 14. The current collecting rod 6 is arranged in the internal space 25 so that the side surface portion 15 is aligned with the central axis of the cylinder. The current collecting rod 6 is further embedded in the gelled negative electrode 5 and is in electrical contact with the gelled negative electrode 5.

[0019] The separator 7 is formed from a flexible sheet of nonwoven fabric made of insulating fibers. Examples of insulating fibers include vinylon and pulp. The separator 7 is formed into a cylindrical shape with a bottom and is disposed between the positive electrode 3 and the gelled negative electrode 5 in the internal space 25, separating the positive electrode 3 and the gelled negative electrode 5. The separator 7 is further disposed between the gelled negative electrode 5 and the bottom portion 16 of the positive electrode can 11 in the internal space 25, separating the gelled negative electrode 5 from the bottom portion 16. The gelled negative electrode 5 is electrically insulated from the positive electrode 3 by the separator 7 separating the positive electrode 3 and the gelled negative electrode 5. The gelled negative electrode 5 is electrically insulated from the positive electrode can 11 by the separator 7 separating the gelled negative electrode 5 from the bottom portion 16.

[0020] 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 25 and permeates the positive electrode 3 and the separator 7, with the positive electrode 3 and the gelled negative electrode 5 being immersed in the electrolyte.

[0021] [Battery manufacturing method according to an embodiment] The battery manufacturing method of the embodiment is a method for manufacturing a battery 1 and includes a negative electrode manufacturing step and a battery assembly step. FIG. 2 is a flowchart showing the negative electrode manufacturing step in the battery manufacturing method of the embodiment. In the negative electrode manufacturing step, a high-concentration potassium hydroxide aqueous solution, a zinc oxide raw material, water, and zinc powder Zn are prepared. The concentration of potassium hydroxide KOH in the high-concentration potassium hydroxide aqueous solution is equal to or higher than a first concentration (e.g., 48 wt.%) that is higher than the concentration of potassium hydroxide KOH in the potassium hydroxide aqueous solution contained in the gelled negative electrode 5 (e.g., 35 wt.%). The zinc oxide raw material is mainly formed from zinc oxide ZnO and contains zinc oxide raw material impurities. The zinc oxide raw material impurities include iron powder Fe and ash.

[0022] A high-concentration potassium hydroxide aqueous solution and a zinc oxide raw material are mixed (step S1), and a zinc oxide mixed electrolyte is produced by the mixing. The zinc oxide mixed electrolyte is heated so that its temperature reaches a predetermined first temperature (e.g., 70°C) or higher (step S2), and changes into a zinc oxide-dissolved electrolyte. During the heating in step S2, even if not all of the zinc oxide ZnO of the zinc oxide raw material is dissolved in the zinc oxide mixed electrolyte, some or all of the zinc oxide ZnO that is not dissolved in the zinc oxide mixed electrolyte will dissolve. That is, potassium hydroxide KOH and zinc oxide ZnO are dissolved in the zinc oxide-dissolved electrolyte, and zinc oxide raw material impurities are not dissolved but are mixed in.

[0023] The zinc oxide-dissolved electrolyte is filtered when the temperature of the zinc oxide-dissolved electrolyte is equal to or higher than the first temperature (step S3), and an impurity-removed electrolyte is produced by the filtration. The impurity-removed electrolyte is a filtrate produced by filtering the zinc oxide-dissolved electrolyte, and is the zinc oxide-dissolved electrolyte from which impurities have been removed. Therefore, the amount of iron powder (Fe) in a unit amount of impurity-removed electrolyte is smaller than the amount of iron powder (Fe) in a unit amount of zinc oxide-dissolved electrolyte.

[0024] The impurity-removed electrolyte is cooled so that the temperature of the impurity-removed electrolyte becomes equal to or lower than a second temperature (for example, room temperature 15°C) that is lower than the first temperature (step S4). The impurity-removed electrolyte is further diluted with water so that the concentration of potassium hydroxide KOH in the impurity-removed electrolyte becomes equal to or lower than a second concentration (for example, 35 wt.%) that is lower than the first concentration (step S5). Through this cooling and dilution, the impurity-removed electrolyte is transformed into a zinc oxide-precipitating electrolyte in which solid zinc oxide ZnO is precipitated.

[0025] That is, the second temperature and the second concentration are set so that when the concentration of potassium hydroxide KOH in the impurity-removed electrolyte is equal to or lower than the second concentration and the temperature of the impurity-removed electrolyte is equal to or lower than the second temperature, a portion of the zinc oxide ZnO dissolved in the impurity-removed electrolyte precipitates as a solid in the zinc oxide-precipitating electrolyte. Also, the amount of zinc oxide raw material mixed with the high-concentration potassium hydroxide aqueous solution in step S1 is set so that a portion of the zinc oxide ZnO dissolved in the impurity-removed electrolyte precipitates as a solid in the zinc oxide-precipitating electrolyte.

[0026] A gelling agent is mixed with the zinc oxide-precipitating electrolyte (step S6), and a gelled electrolyte is produced by the mixing. The gelled electrolyte is formed into a gel. Zinc powder Zn is mixed with the gelled electrolyte (step S7), and a gelled negative electrode 5 is produced by the mixing.

[0027] In the battery assembly process, a positive electrode can without the beading portion 21 and curled portion 22, a positive electrode 3, a separator 7, an electrolyte, and a gelled negative electrode 5 produced in the negative electrode production process are prepared. The positive electrode 3 is inserted into the positive electrode can 11 through the opening 17 so that the outer surface of the positive electrode 3 contacts the inner surface of the positive electrode can 11. The positive electrode can 11 is processed so that the beading portion 21 is formed after the positive electrode 3 is inserted into the positive electrode can 11. The beading portion 21 prevents the positive electrode 3 from slipping out of the positive electrode can 11 through the opening 17. After the positive electrode 3 is inserted into the positive electrode can 11, the separator 7 is inserted into the positive electrode 3 through the opening 17.

[0028] After the separator 7 is inserted inside the positive electrode 3, the electrolyte is injected into the inside of the positive electrode 3 through the opening 17. By injecting the electrolyte into the inside of the positive electrode 3, the electrolyte impregnates the separator 7 and then the positive electrode 3. After the separator 7 and the positive electrode 3 are impregnated with the electrolyte, the gelled negative electrode 5 is injected inside the separator 7.

[0029] In the battery assembly process, a current collecting rod 6, a negative electrode terminal plate 12, and a sealing gasket 14 are also prepared. The current collecting rod 6, the negative electrode terminal plate 12, and the sealing gasket 14 are assembled and fixed to one another so that the current collecting rod 6 is in electrical contact with the negative electrode terminal plate 12 and so that the edge of the negative electrode terminal plate 12 is covered by the sealing gasket 14, thereby producing a sealing body. After the gelled negative electrode 5 is injected, the sealing body is attached to the positive electrode can so that the current collecting rod 6 is embedded in the gelled negative electrode 5 and so that the periphery of the sealing gasket 14 is in contact with the beading portion 21. The sealing body is positioned appropriately relative to the positive electrode can by the periphery of the sealing gasket 14 contacting the beading portion 21.

[0030] After the sealing body is positioned in an appropriate position relative to the positive electrode can, the positive electrode can is crimped to form a curled portion 22 on the positive electrode can, thereby producing the positive electrode can 11. By forming the curled portion 22 on the positive electrode can 11, the sealing body is fixed to the positive electrode can 11 so that it does not come off from the positive electrode can 11. By forming the curled portion 22 on the positive electrode can 11, the gap formed between the negative electrode terminal plate 12 and the positive electrode can 11 is further sealed with the sealing gasket 14, and the internal space 25 is sealed from the outside, thereby producing the battery 1. According to this battery manufacturing method, the battery 1 can be appropriately manufactured so that the amount of iron powder (Fe) contained in the gelled negative electrode 5 is reduced.

[0031] When the battery 1 is connected to a load, the battery 1 discharges so that electricity flows to the load. When the gelled negative electrode 5 contains iron powder (Fe), the battery 1 may generate gas in the internal space 25. The battery 1 has a reduced amount of iron powder (Fe) contained in the gelled negative electrode 5, which can prevent gas from being generated in the internal space 25 when the battery 1 is not charged. When the battery 1 is charged due to misuse, gas may be generated in the internal space 25. When the battery 1 is charged due to misuse, the battery 1 has a gelled negative electrode 5 containing zinc oxide (ZnO), which can prevent gas from being generated in the internal space 25 when the battery 1 is charged due to misuse.

[0032] The pressure in internal space 25 increases due to the generation of gas in internal space 25. When the pressure in internal space 25 exceeds a predetermined pressure, pressure release valve 27 ruptures, causing leakage of the electrolyte or gas stored in internal space 25 to the outside. Battery 1 can prevent rupture, in which the sealing body comes off from positive electrode can 11, due to leakage occurring when the pressure in internal space 25 increases.

[0033] [Battery 1 evaluation test] To confirm the effects of the battery 1 of the embodiment, a battery of an example and a battery of a comparative example 1 were fabricated. The battery of the example was formed from the battery 1 of the embodiment described above and was fabricated by the battery manufacturing method of the embodiment described above. The battery of the comparative example 1 was fabricated by the battery manufacturing method of the comparative example 1.

[0034] [Battery manufacturing method of Comparative Example 1] The battery manufacturing method of Comparative Example 1 replaces the negative electrode manufacturing step of the battery manufacturing method of the previously described embodiment with another negative electrode manufacturing step, and includes a battery assembly step, similar to the battery manufacturing methods of the previously described embodiment. Figure 3 is a flowchart showing the negative electrode manufacturing step in the battery manufacturing method of Comparative Example 1. In the negative electrode manufacturing step in the battery manufacturing method of Comparative Example 1, an aqueous potassium hydroxide solution for the negative electrode, zinc oxide raw material, water, and zinc powder Zn are prepared. The concentration of potassium hydroxide (KOH) in the aqueous potassium hydroxide solution for the negative electrode is equal to the concentration (35 wt.%) of potassium hydroxide (KOH) in the aqueous potassium hydroxide solution contained in the gelled negative electrode 5.

[0035] The potassium hydroxide aqueous solution for the negative electrode and the zinc oxide raw material are mixed at room temperature (step S11), and a zinc oxide-dissolved electrolyte is produced by the mixing. In the zinc oxide-dissolved electrolyte, potassium hydroxide (KOH) and zinc oxide (ZnO) are dissolved, and impurities of the zinc oxide raw material are not dissolved and are mixed in.

[0036] The zinc oxide-dissolved electrolyte is filtered (step S12), and a post-impurity-removed electrolyte is produced by the filtration. The post-impurity-removed electrolyte is a filtrate produced by filtering the zinc oxide-dissolved electrolyte, and is obtained by removing the remaining zinc oxide ZnO and zinc oxide raw material impurities from the zinc oxide-dissolved electrolyte. Therefore, the amount of iron powder Fe in a unit amount of the post-impurity-removed electrolyte is smaller than the amount of iron powder Fe in a unit amount of the zinc oxide-dissolved electrolyte.

[0037] A gelling agent is mixed with the impurity-removed electrolyte (step S13), and a gelled electrolyte is produced by the mixing. The gelled electrolyte is formed into a gel. Zinc powder Zn is mixed with the gelled electrolyte (step S14), and a gelled negative electrode is produced by the mixing. The concentration of zinc oxide ZnO in the impurity-removed electrolyte produced by the filtration in step S12 is lower than the solubility of zinc oxide ZnO in a unit amount of impurity-removed electrolyte because the zinc oxide ZnO contained in the impurity-removed electrolyte is dissolved in the impurity-removed electrolyte. Therefore, the concentration of zinc oxide ZnO in the gelled negative electrode produced by the negative electrode production step of the battery production method of Comparative Example 1 is lower than the concentration of zinc oxide ZnO in the gelled negative electrode 5 of Battery 1 produced by the battery production method of the above-described embodiment.

[0038] In the battery assembly step in the battery manufacturing method of Comparative Example 1, similar to the negative electrode manufacturing step in the previously described embodiment, a battery is manufactured using a gelled negative electrode manufactured in the negative electrode manufacturing step in the battery manufacturing method of Comparative Example 1. That is, similar to battery 1 in the previously described embodiment, the battery of Comparative Example 1 includes a battery case 2, a positive electrode 3, a current collector 6, and a separator 7, and the gelled negative electrode 5 of battery 1 in the previously described embodiment is replaced with a gelled negative electrode manufactured in the negative electrode manufacturing step in the battery manufacturing method of Comparative Example 1.

[0039] The battery of the Example and the battery of Comparative Example 1 were fabricated in the same manner except for the gelled negative electrodes. For example, the battery of the Example and the battery of Comparative Example 1 were fabricated using a positive electrode 3, a current collector rod 6, a separator 7, a positive electrode can 11, a negative electrode terminal plate 12, and a sealing gasket 14 that were fabricated so that the battery size was equivalent to that of an AA battery (LR6 size).

[0040] The zinc oxide mixed electrolyte used to fabricate the battery of Comparative Example 1 was produced by adding 5 wt.% zinc oxide ZnO to a 35 wt.% potassium hydroxide aqueous solution. That is, the impurity-removed electrolyte used to fabricate the battery of Comparative Example 1 contained 33.3 wt.% potassium hydroxide KOH, 61.9 wt.% water, and 4.8 wt.% zinc oxide ZnO.

[0041] The zinc oxide mixed electrolyte used to fabricate the battery of the example was prepared by adding 10 wt.% zinc oxide (ZnO) to a 48 wt.% potassium hydroxide aqueous solution. The zinc oxide mixed electrolyte was heated to 70°C, producing a zinc oxide dissolved electrolyte in which zinc oxide (ZnO) was dissolved. The impurity-removed electrolyte obtained by filtering the zinc oxide dissolved electrolyte was cooled to 25°C and diluted with water to a potassium hydroxide (KOH) concentration of 35 wt.%. The cooling and dilution produced a zinc oxide precipitated electrolyte in which solid zinc oxide (ZnO) was precipitated. That is, the zinc oxide precipitated electrolyte used to fabricate the battery of the example contained 32.6 wt.% potassium hydroxide (KOH), 60.6 wt.% water, and 6.8 wt.% zinc oxide (ZnO).

[0042] Table 1 shows the composition of the gelled negative electrode of the battery of Comparative Example 1 and the composition of the gelled negative electrode 5 of the battery of the Example. [Table 1] The gelled negative electrode of the battery of Example was formed from a blend of 2.0 g of gelling agent, 33.7 g of zinc oxide precipitated electrolyte, and 65.0 g of zinc powder Zn, and contained 0.12 g of gelling agent, 2.02 g of zinc oxide precipitated electrolyte, and 3.90 g of zinc powder Zn per battery. The gelled negative electrode of the battery of Comparative Example 1 was formed from a blend of 2.0 g of gelling agent, 33.0 g of impurity-removed electrolyte, and 65.0 g of zinc powder Zn, and contained 0.12 g of gelling agent, 1.98 g of impurity-removed electrolyte, and 3.90 g of zinc powder Zn per battery. At this time, the amount of zinc oxide ZnO contained in the gelled negative electrode of the battery of Comparative Example 1 is less than the amount of zinc oxide ZnO contained in the gelled negative electrode of the battery of Comparative Example 1, since the amount of zinc oxide ZnO contained in the gelled negative electrode of the battery of Comparative Example 1 is less than the amount of zinc oxide ZnO contained in the gelled negative electrode 5 of the battery of the Example.

[0043] To confirm the effects of the battery 1 of the embodiment, a 4-series 1 reverse test was also performed on the battery of the example and the battery of Comparative Example 1. For the 4-series 1 reverse test performed on the test battery 30, an electric circuit 31 was fabricated as shown in FIG. 4. FIG. 4 is a circuit diagram showing the electric circuit 31 used in the 4-series 1 reverse test. The electric circuit 31 includes three batteries 32-1 to 32-3 and a 43 Ω resistor 33. Each of the three batteries 32-1 to 32-3 was fabricated in the same manner as the test battery 30. The three batteries 32-1 to 32-3 were connected in series. That is, the positive terminal of the first battery 32-1 of the three batteries 32-1 to 32-3 was connected to the negative terminal of the second battery 32-2 of the three batteries 32-1 to 32-3. The positive terminal of the second battery 32-2 was connected to the negative terminal of the third battery 32-3 of the three batteries 32-1 to 32-3. The positive terminal of the third battery 32-3 is connected to the positive terminal of the test battery 30. One terminal of the resistor 33 is connected to the negative terminal of the first battery 32-1, and the other terminal of the resistor 33 is connected to the negative terminal of the test battery 30. In other words, the test battery 30 is connected in reverse to the three batteries 32-1 to 32-3. In the 4-series 1-reverse test performed on the test battery 30, the electrical circuit 31 is left for one day with electricity generated by the test battery 30 and the three batteries 32-1 to 32-3 flowing through the resistor 33, and then it is confirmed whether or not the test battery 30 has leaked.

[0044] Table 2 shows the results of the 4-series 1-reverse test of the battery of the example and the results of the 4-series 1-reverse test of the battery of Comparative Example 1. [Table 2] The 4-series 1 reverse test results for the batteries of the Example indicate values ​​calculated by dividing the number of batteries that leaked out of the five batteries by 5 when five sets of 4-series 1 reverse tests were performed on five batteries fabricated as the batteries of the Example. The 4-series 1 reverse test results for the batteries of Comparative Example 1 indicate values ​​calculated by dividing the number of batteries that leaked out of the five batteries by 5 when five sets of 4-series 1 reverse tests were performed on five batteries fabricated as the batteries of Comparative Example 1.

[0045] Table 2 shows that the 4-series 1-reverse test result for the battery of the Example was 100%, and the 4-series 1-reverse test result for the battery of Comparative Example 1 was 0%. That is, Table 2 shows that the battery of the Example can suppress leakage when charged due to misuse compared to the battery of Comparative Example 1, and that the battery of the Example can suppress gas generation inside the battery when charged due to misuse compared to the battery of Comparative Example 1.

[0046] [Battery manufacturing method of Comparative Example 2] The battery manufacturing method of Comparative Example 2 further replaces the negative electrode manufacturing step of the battery manufacturing method of the previously described embodiment with another negative electrode manufacturing step, and includes a battery assembly step, similar to the battery manufacturing method of the previously described embodiment. FIG. 5 is a flowchart showing the negative electrode manufacturing step in the battery manufacturing method of Comparative Example 2. In the negative electrode manufacturing step in the battery manufacturing method of Comparative Example 2, an aqueous potassium hydroxide solution for the negative electrode, zinc oxide raw material, water, and zinc powder Zn are prepared. The concentration of potassium hydroxide (KOH) in the aqueous potassium hydroxide solution for the negative electrode is equal to the concentration of potassium hydroxide (KOH) in the aqueous potassium hydroxide solution contained in the gelled negative electrode 5 (e.g., 35 wt.%).

[0047] The potassium hydroxide aqueous solution for the negative electrode and the zinc oxide raw material are mixed (step S21), and a zinc oxide mixed electrolyte is produced by the mixing. In the zinc oxide mixed electrolyte, potassium hydroxide KOH and zinc oxide ZnO are dissolved, and impurities of the zinc oxide raw material are mixed in without being dissolved.

[0048] The zinc oxide mixed electrolyte is filtered (step S22), and a post-impurity-removed electrolyte is produced by the filtration. The post-impurity-removed electrolyte is a filtrate produced by filtering the zinc oxide dissolved electrolyte, and is obtained by removing zinc oxide raw material impurities from the zinc oxide dissolved electrolyte. Therefore, the amount of iron powder (Fe) in a unit amount of the post-impurity-removed electrolyte is smaller than the amount of iron powder (Fe) in a unit amount of the zinc oxide dissolved electrolyte.

[0049] After the impurities are removed, the electrolyte is mixed with a gelling agent (step S23), which produces a gelled electrolyte. The gelled electrolyte is formed into a gel. The gelled electrolyte is mixed with zinc powder Zn and then with zinc oxide raw material (step S24), which produces a gelled negative electrode.

[0050] In the battery assembly step in the battery manufacturing method of Comparative Example 2, similar to the negative electrode manufacturing step in the previously described embodiment, a battery is manufactured using a gelled negative electrode manufactured in the negative electrode manufacturing step in the battery manufacturing method of Comparative Example 2. That is, similar to battery 1 in the previously described embodiment, the battery of Comparative Example 2 includes a battery case 2, a positive electrode 3, a current collector 6, and a separator 7, and the gelled negative electrode 5 of battery 1 in the previously described embodiment is replaced with a gelled negative electrode manufactured in the negative electrode manufacturing step in the battery manufacturing method of Comparative Example 2.

[0051] In the battery of Comparative Example 2 produced by the battery manufacturing method of Comparative Example 2, the zinc oxide raw material is added to the gelled electrolyte in step S24, and thus, like battery 1 produced by the battery manufacturing method of the previously described embodiment, a larger amount of zinc oxide ZnO can be contained in the gelled negative electrode than the solubility of zinc oxide ZnO in the electrolyte after impurities are removed. In the battery of Comparative Example 2, because a larger amount of zinc oxide ZnO is contained in the gelled negative electrode, like battery 1 of the previously described embodiment, generation of gas in internal space 25 when the battery is charged due to misuse can be suppressed, and leakage can be suppressed.

[0052] In the battery of Comparative Example 2, impurities contained in the zinc oxide raw material added to the gelled electrolyte in step S24 were not removed, and therefore, iron powder (Fe) contained in the zinc oxide raw material added to the gelled electrolyte in step S24 was contained in the gelled negative electrode. For example, the value calculated by dividing the amount of iron powder contained in the gelled negative electrode of the battery of Comparative Example 2 by the amount of solid zinc oxide (ZnO) contained in the gelled negative electrode is equal to or greater than the value calculated by dividing the amount of iron powder (Fe) contained in the zinc oxide raw material by the amount of zinc oxide (ZnO) contained in the zinc oxide raw material. Therefore, the battery of Comparative Example 2 contains a larger amount of iron powder (Fe) in the gelled negative electrode than battery 1 fabricated by the battery manufacturing method of the previously described embodiment. Compared to the battery of Comparative Example 2, battery 1 of the previously described embodiment can reduce the amount of iron powder (Fe) contained in gelled negative electrode 5, thereby suppressing gas generation in internal space 25 when the battery is not in use and suppressing electrolyte leakage.

[0053] [Advantages of Battery 1 of the Embodiment] The battery 1 of this embodiment includes a positive electrode 3, a gelled negative electrode 5, and an electrolyte in which the positive electrode 3 and the gelled negative electrode 5 are immersed. The gelled negative electrode 5 contains zinc powder Zn, a potassium hydroxide aqueous solution, and zinc oxide ZnO in an amount greater than the solubility of zinc oxide ZnO in the potassium hydroxide aqueous solution. The value calculated by dividing the mass of iron powder Fe contained in the gelled negative electrode 5 by the mass of solid zinc oxide ZnO contained in the gelled negative electrode 5 is smaller than the value calculated by dividing the mass of iron powder Fe contained in the zinc oxide raw material used to prepare the gelled negative electrode 5 by the mass of zinc oxide ZnO contained in the zinc oxide raw material. Because the gelled negative electrode 5 contains zinc oxide ZnO in an amount greater than the solubility of zinc oxide ZnO, the battery 1 of this embodiment can suppress gas generation inside the battery and suppress leakage when charged due to misuse. In the battery 1 of the embodiment, since the gelled negative electrode 5 contains a small amount of iron powder Fe, gas generation inside the battery can be suppressed when not being charged, and leakage can be suppressed.

[0054] [Effects of the battery manufacturing method according to the embodiment] The battery manufacturing method of the embodiment is a method for manufacturing the battery 1 of the embodiment, and includes filtering a zinc oxide-dissolved electrolyte solution in which potassium hydroxide KOH and zinc oxide ZnO are dissolved (step S3), cooling the impurity-removed electrolyte solution produced by filtering the zinc oxide-dissolved electrolyte solution and diluting it with water so that solid zinc oxide ZnO precipitates in the impurity-removed electrolyte solution (steps S4 and S5), and preparing a gelled negative electrode 5 so that the gelled negative electrode 5 further contains the zinc oxide-precipitated electrolyte solution produced by cooling the impurity-removed electrolyte solution and diluting it with water (steps S6 and S7). The battery 1 manufactured by the battery manufacturing method of the embodiment contains zinc oxide ZnO in the gelled negative electrode 5 in an amount greater than the solubility thereof, thereby preventing gas generation inside the battery and preventing leakage when the battery is charged due to misuse. The battery 1 produced by the battery manufacturing method of the embodiment can reduce the amount of iron powder Fe contained in the gelled negative electrode 5, and can suppress the generation of gas inside the battery when the battery 1 is not being charged, thereby suppressing the occurrence of leakage.

[0055] In the battery manufacturing method of the above-described embodiment, the electrolyte solution after impurity removal is cooled and then diluted with water, but the electrolyte solution after impurity removal may be cooled after being diluted with water. Even in such a case, the battery manufacturing method can precipitate zinc oxide ZnO in the zinc oxide-precipitating electrolyte solution, reduce the amount of iron powder Fe contained as an impurity in the gelled negative electrode 5, suppress gas generation inside the battery, and suppress leakage.

[0056] In the battery manufacturing method of the above-described embodiment, the post-impurity-removal electrolyte is diluted with water. However, dilution of the post-impurity-removal electrolyte with water may be omitted. When dilution of the post-impurity-removal electrolyte with water is omitted, in the battery manufacturing method, the high-concentration potassium hydroxide aqueous solution is replaced with a potassium hydroxide aqueous solution for the negative electrode, and a zinc oxide mixed electrolyte obtained by mixing the potassium hydroxide aqueous solution for the negative electrode and a zinc oxide raw material is heated to dissolve zinc oxide ZnO, and the post-impurity-removal electrolyte is cooled to precipitate zinc oxide ZnO. In this case, as with the battery manufacturing method of the above-described embodiment, the battery manufacturing method can appropriately produce a gelled negative electrode 5, reduce the amount of iron powder (Fe) contained as an impurity in the gelled negative electrode 5, and suppress gas generation inside the battery.

[0057] In the battery manufacturing method of the above-described embodiment, the electrolyte solution after impurity removal is cooled, but cooling the electrolyte solution after impurity removal may be omitted. When cooling the electrolyte solution after impurity removal is omitted, in the battery manufacturing method, the zinc oxide mixed electrolyte solution is filtered without heating to produce the electrolyte solution after impurity removal, and the zinc oxide precipitated electrolyte solution is produced by diluting the electrolyte solution after impurity removal with water. In this case, as with the battery manufacturing method of the above-described embodiment, the battery manufacturing method can appropriately produce the gelled negative electrode 5, reduce the amount of iron powder (Fe) contained as an impurity in the gelled negative electrode 5, and suppress gas generation inside the battery.

[0058] In the battery manufacturing method according to the embodiment described above, the iron powder (Fe) is removed from the zinc oxide-dissolved electrolyte by filtration. However, the iron powder (Fe) may be removed from the zinc oxide-dissolved electrolyte by a separation technique other than filtration. An example of such a separation technique is magnetic separation, which separates the iron powder (Fe) from the zinc oxide-dissolved electrolyte using magnetic force. Even when such a separation technique is used, the battery manufacturing method can reduce the amount of iron powder (Fe) contained as an impurity in the gelled negative electrode 5, suppress gas generation inside the battery, and suppress leakage.

[0059] The negative electrode fabrication step of the battery manufacturing method described above is used to fabricate a gelled negative electrode 5 for an alkaline manganese dry battery. However, it may also be used to fabricate a negative electrode for a battery other than an alkaline manganese dry battery. An example of such a battery is a zinc secondary battery. Even when the negative electrode fabrication step is used to fabricate a negative electrode for such a battery, the battery manufacturing method can reduce the amount of iron powder (Fe) contained as an impurity in the negative electrode, suppress gas generation inside the battery, and suppress leakage.

[0060] Although the embodiments have been described above, the embodiments are not limited to the above content. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components 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 spirit of the embodiments. [Explanation of symbols]

[0061] 1:Battery 3: Positive electrode 5: Gel negative electrode

Claims

1. A positive electrode and a negative electrode containing zinc; An electrolyte in which the positive electrode and the negative electrode are immersed and a battery A battery manufacturing method for manufacturing a battery, removing solid materials from a zinc oxide-dissolving electrolyte in which potassium hydroxide and zinc oxide are dissolved; treating the impurity-removed electrolyte produced by removing the substance from the zinc oxide-dissolved electrolyte so that solid zinc oxide precipitates in the impurity-removed electrolyte; and preparing the negative electrode so that the negative electrode further contains a zinc oxide depositing electrolyte produced by treating the electrolyte after removing the impurities. A battery manufacturing method comprising:

2. The impurity-removed electrolyte is a filtrate produced by filtering the zinc oxide-dissolved electrolyte. The battery manufacturing method according to claim 1 .

3. the zinc oxide dissolved electrolyte is removed from the material when the temperature of the zinc oxide dissolved electrolyte is higher than a first temperature; The impurity-removed electrolyte is cooled so that the temperature of the impurity-removed electrolyte becomes lower than a second temperature that is lower than the first temperature, thereby precipitating solid zinc oxide in the impurity-removed electrolyte. The battery manufacturing method according to claim 1 .

4. the zinc oxide-dissolved electrolyte is such that the substance is removed when the concentration of potassium hydroxide in the zinc oxide-dissolved electrolyte is greater than a first concentration; The impurity-removed electrolyte is diluted with water so that the concentration of potassium hydroxide in the impurity-removed electrolyte is lower than a second concentration that is lower than the first concentration, thereby precipitating solid zinc oxide in the impurity-removed electrolyte. The battery manufacturing method according to claim 1 .

5. the zinc oxide-dissolved electrolyte is such that the substance is removed when the temperature of the zinc oxide-dissolved electrolyte is higher than a first temperature and when the concentration of potassium hydroxide in the zinc oxide-dissolved electrolyte is higher than a first concentration; The impurity-removed electrolyte is cooled so that the temperature of the impurity-removed electrolyte becomes lower than a second temperature that is lower than the first temperature, and the impurity-removed electrolyte is diluted with water so that the concentration of potassium hydroxide in the impurity-removed electrolyte becomes lower than a second concentration that is lower than the first concentration, thereby precipitating solid zinc oxide in the impurity-removed electrolyte. The battery manufacturing method according to claim 1 .

6. A positive electrode and a negative electrode; an electrolyte in which the positive electrode and the negative electrode are immersed; The negative electrode is Zinc and an aqueous potassium hydroxide solution; The potassium hydroxide aqueous solution contains zinc oxide in an amount greater than the solubility of zinc oxide in the aqueous solution, The value calculated by dividing the amount of iron powder contained in the negative electrode by the amount of solid zinc oxide contained in the negative electrode is smaller than the value calculated by dividing the amount of iron powder contained in a zinc oxide raw material used in producing the negative electrode by the amount of zinc oxide contained in the zinc oxide raw material. battery.

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