Battery and battery manufacturing method

Abstract

To suppress reduction of discharge performance even when bottom paper is provided.SOLUTION: A battery 1 comprises: a cathode can 11; a cathode 3 disposed inside of the cathode can 11; an anode 5 disposed in the anode loading hole 28 formed in the cathode 3; a separator 7 formed cylindrical and disposed between the anode 5 and the cathode 3; and bottom paper 8. The bottom paper 8 includes a side portion 32, which is disposed between the end 39 of the separator 7 and the anode 3, and a bottom portion 31 enclosed by the side portion 32. The bottom portion 31 is disposed between the anode 5 and the cathode can 11. An inner diameter of a large inner diameter hole portion 33, where the bottom paper 8 is disposed, in the anode loading hole 28 is larger than an inner diameter of a small inner diameter hole portion 34, where the bottom paper 8 is not disposed, in the anode loading hole 28.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The disclosed technology relates to batteries and battery manufacturing methods. [Background technology]

[0002] An alkaline dry battery is known that has a bottom paper that is separate from a cylindrical separator that separates the positive and negative electrodes (Patent Document 1). The bottom paper covers the opening of the separator and separates the positive electrode can and the negative electrode. Such an alkaline dry battery can appropriately prevent the negative electrode from being electrically shorted to the positive electrode can. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-334878 Summary of the Invention [Problem to be solved by the invention]

[0004] The bottom paper may have a bottom portion disposed between the positive electrode can and the negative electrode, and a side portion surrounding the bottom portion and disposed between the edge of the separator on the opening side and the positive electrode. In such alkaline dry batteries, if a gap is formed between the separator and the positive electrode where the positive electrode and negative electrode are not filled, and the amount of positive electrode active material and negative electrode active material filled inside the positive electrode can is reduced by the amount of the gap, an increase in internal resistance occurs, resulting in a decrease in discharge performance and a decrease in reaction efficiency.

[0005] The disclosed technology has been made in consideration of these points, and aims to provide a battery and a battery manufacturing method that suppresses deterioration of discharge performance even when a bottom paper is provided. [Means for solving the problem]

[0006] A battery according to one embodiment of the present disclosure comprises a positive electrode can, a positive electrode disposed inside the positive electrode can, a negative electrode disposed in a negative electrode filling hole formed in the positive electrode, a separator formed in a cylindrical shape and disposed between the negative electrode and the positive electrode, and a bottom paper, the bottom paper having a side portion disposed between the separator and the positive electrode and a bottom portion surrounded by the side portion, the bottom portion being disposed between the negative electrode and the positive electrode can, and the diameter of a large inner diameter hole portion of the negative electrode filling hole in which the bottom paper is disposed is larger than the diameter of a small inner diameter hole portion of the negative electrode filling hole in which the bottom paper is not disposed. Effect of the Invention

[0007] The disclosed battery and battery manufacturing method can suppress the deterioration of discharge performance. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a battery according to an embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view showing a part of the battery according to the embodiment. [Diagram 3] FIG. 3 is a flowchart showing a battery manufacturing method according to an embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a molding mix fitting step in which a positive electrode is inserted into a positive electrode can during processing. [Diagram 5] FIG. 5 is an enlarged cross-sectional view showing a part of the battery of the comparative example. [Figure 6] FIG. 6 is a flowchart showing a battery manufacturing method of a comparative example. [Figure 7] FIG. 7 is a cross-sectional view showing an internal can pressurization step for forming a positive electrode inside a positive electrode can during processing in a battery manufacturing method of the comparative example. [Figure 8] FIG. 8 is an enlarged cross-sectional view showing a modified battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a battery and a battery manufacturing method according to an embodiment disclosed in the present application 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 explanations will be omitted.

[0010] The battery 1 of the embodiment is an alkaline dry battery, and as shown in Fig. 1, includes a battery case 2, a positive electrode 3, a negative electrode 5, a current collector 6, a separator 7, and a bottom paper 8. Fig. 1 is a cross-sectional view showing the battery 1 of the 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 formed in a cylindrical shape and is disposed along the side of the cylinder. The bottom portion 16 is formed in a disk shape with unevenness and is 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 is formed with 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 inside of the positive electrode can 11 is connected to the outside of the positive electrode can 11 via the opening 17. The positive electrode terminal portion 18 is formed in the center of the bottom portion 16. The positive electrode terminal portion 18 is formed so as to protrude from the inside of the positive electrode can 11 toward the outside.

[0012] A beading portion 21 and a curled portion 22 are formed in the side portion 15 of the positive electrode can 11. The beading portion 21 is formed in the vicinity of the open end 23 of the side 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 portion 15 toward the inside of the positive electrode can 11, that is, so that the inner diameter of the portion of the side portion 15 where the beading portion 21 is formed is smaller than the inner diameter of the other portions. 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 portion 15 becomes smaller as it approaches the open end 23.

[0013] Negative electrode terminal plate 12 is made of a conductor such as a metal and is formed in a generally disk shape. Negative electrode terminal plate 12 is disposed along the other bottom surface of the cylinder and closes opening 17 of positive electrode can 11. Inside battery case 2, negative electrode terminal plate 12 closes opening 17, thereby forming internal space 25 surrounded by positive electrode can 11 and 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 disposed 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 so that the sealing gasket 14 does not move 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 so that the sealing gasket 14 does not slip out from inside the positive electrode can 11. The negative electrode terminal plate 12 is fixed to the sealing gasket 14 by a part of the sealing gasket 14 being 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 sandwiching the sealing gasket 14 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 relief valve 27. The pressure relief valve 27 is a portion of the sealing gasket 14 that is thin in thickness.

[0016] The positive electrode 3 is electrolytic manganese dioxide MnO 2 It contains graphite C, potassium hydroxide solution, and binder. Electrolytic manganese dioxide MnO 2 is a positive electrode active material. The binder contains, for example, a polymer compound, and electrolytic manganese dioxide MnO 2 and graphite C are bonded together to form a solid. The positive electrode 3 includes three pellets. Each of the three pellets is formed into a cylindrical shape. The three pellets are arranged so that the three through holes formed in each of the three pellets are connected to each other to form the positive electrode 3. That is, the positive electrode 3 is formed into 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 portion 15 of the positive electrode can 11. The positive electrode 3 is formed of electrolytic manganese dioxide MnO 2 and graphite C are in intimate contact with side surface portion 15 of positive electrode can 11 so as to be electrically connected to positive electrode can 11.

[0017] The negative electrode 5 contains zinc powder, an aqueous potassium hydroxide solution, and a thickener, and is formed in a gel form. The zinc powder is made of metal zinc. The zinc powder may be replaced with another negative electrode active material. Examples of other negative electrode active materials include zinc alloy powder made of a zinc alloy containing zinc. Examples of the thickener include polyacrylic acid, polyacrylate, polyethylene glycol PEG, polyethylene oxide PEO, and carboxymethyl cellulose CMC. Examples of the polyacrylate include sodium polyacrylate and potassium polyacrylate. The negative electrode 5 is disposed in the negative electrode filling hole 28 of the positive electrode 3 in the internal space 25 of the battery case 2.

[0018] The current collecting rod 6 is formed of 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 electrically connected to the negative electrode terminal plate 12. The current collecting rod 6 further penetrates the 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 disposed in the internal space 25 so as to be aligned with the central axis of the cylinder along which the side portion 15 is aligned. The current collecting rod 6 is further embedded in the negative electrode 5 and is electrically connected to the negative electrode 5.

[0019] The separator 7 is a nonwoven fabric using insulating fibers, formed from a flexible sheet, and formed into a hollow cylindrical shape. Examples of materials for the nonwoven fabric include vinylon and pulp. The separator 7 is disposed between the positive electrode 3 and the negative electrode 5 in the internal space 25. The separator 7 separates the positive electrode 3 and the negative electrode 5. 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.

[0020] The battery 1 further includes an electrolyte. The electrolyte is formed of an aqueous solution containing potassium hydroxide (KOH). The electrolyte is disposed in the internal space 25 so that the positive electrode 3 and the negative electrode 5 are immersed in the electrolyte, and the electrolyte permeates the positive electrode 3, the negative electrode 5, and the separator 7.

[0021] The battery 1 further includes an insulating washer and a label, which are not shown. The insulating washer is made of an insulator and is generally ring-shaped. The insulating washer is disposed between the open end 23 and the negative terminal plate 12, and prevents an electrical short circuit between the positive can 11 and the negative terminal plate 12. The label is made of a sheet made of an insulator. The label covers the area of ​​the outer surface of the positive can 11 excluding the positive terminal portion 18. The label further supports the insulating washer so that the insulating washer does not come off the battery 1.

[0022] FIG. 2 is an enlarged cross-sectional view showing a part of the battery 1 of the embodiment. The bottom paper 8 is a nonwoven fabric using insulating fibers, formed into a circular sheet shape, and has flexibility. Examples of materials constituting the nonwoven fabric include vinylon and pulp. The bottom paper 8 is bent into a cup shape and includes a bottom portion 31 and a side portion 32. The bottom portion 31 is formed into a flat disk shape. The side portion 32 is adjacent to the edge of the bottom portion 31 and connected to the bottom portion 31, and follows the side surface of the cylinder. The side portion 32 is wrinkled as the side portion 32 follows the side surface of the cylinder.

[0023] The negative electrode filling hole 28 formed in the positive electrode 3 is formed of a large inner diameter hole portion 33 and a small inner diameter hole portion 34. The large inner diameter hole portion 33 is formed in a cylindrical shape. That is, the inner diameter of the large inner diameter hole portion 33 does not change depending on the position in the longitudinal direction of the negative electrode filling hole 28 and is generally constant. The large inner diameter hole portion 33 is formed at the end of the positive electrode 3 on the side of the bottom surface portion 16 of the positive electrode can 11. The small inner diameter hole portion 34 is formed in a cylindrical shape. The inner diameter of the small inner diameter hole portion 34 does not change depending on the position in the longitudinal direction of the negative electrode filling hole 28 and is generally constant. The inner diameter of the large inner diameter hole portion 33 is larger than the inner diameter of the small inner diameter hole portion 34. The small inner diameter hole portion 34 is a portion of the negative electrode filling hole 28 that is different from the large inner diameter hole portion 33, is connected to the large inner diameter hole portion 33, and is formed on the side of the opening 17 of the positive electrode can 11 from the large inner diameter hole portion 33. Therefore, a step is formed at the boundary between the large inner diameter hole portion 33 and the small inner diameter hole portion 34 in the positive electrode 3.

[0024] The negative electrode filling hole 28 is formed so that the inner diameter of the large inner diameter hole portion 33 is approximately equal to the diameter of the bottom portion 31 of the bottom paper 8. The negative electrode filling hole 28 is further formed so that the length of the large inner diameter hole portion 33 in the longitudinal direction of the negative electrode filling hole 28 is approximately equal to the height of the side portion 32 of the bottom paper 8. The negative electrode filling hole 28 is further formed so that the step between the large inner diameter hole portion 33 and the small inner diameter hole portion 34 is approximately equal to the thickness of the side portion 32 of the bottom paper 8. In other words, the positive electrode 3 is formed so that the inner peripheral surface of the small inner diameter hole portion 34 of the positive electrode 3 is approximately flush with the inner peripheral surface of the side portion 32 of the bottom paper 8.

[0025] The large inner diameter hole portion 33 is formed in one pellet 35 on the side of the bottom surface portion 16 of the positive electrode can 11 among the three pellets formed in the positive electrode 3. In the pellet 35, a part of the small inner diameter hole portion 34 on the side of the large inner diameter hole portion 33 is further formed. That is, the pellet 35 includes a large inner diameter positive electrode portion 36 and a small inner diameter positive electrode portion 37. In the large inner diameter positive electrode portion 36, the small inner diameter hole portion 34 is not formed, and the large inner diameter hole portion 33 is formed. In the small inner diameter positive electrode portion 37, the large inner diameter hole portion 33 is not formed, and a part of the small inner diameter hole portion 34 is formed. The small inner diameter positive electrode portion 37 is connected to the large inner diameter positive electrode portion 36 and is formed integrally with the large inner diameter positive electrode portion 36. In the other pellet of the three pellets different from the pellet 35, the large inner diameter hole portion 33 is not formed, and a part of the small inner diameter hole portion 34 is formed.

[0026] The bottom paper 8 is disposed in the large inner diameter hole portion 33 such that the bottom portion 31 is disposed between the negative electrode 5 and the bottom portion 16 of the positive electrode can 11 in the internal space 25, and the side portion 32 is disposed between the end 39 of the separator 7 on the side of the bottom portion 16 and the positive electrode 3, and the side portion 32 is not disposed in the small inner diameter hole portion 34. That is, the bottom paper 8 separates the negative electrode 5 from the bottom portion 16 of the positive electrode can 11. The negative electrode 5 is electrically insulated from the positive electrode can 11 by the bottom paper 8 separating the negative electrode 5 from the bottom portion 16 of the positive electrode can 11.

[0027] The end 39 of the separator 7 is not tapered or wrinkled because the inner circumferential surface of the small inner diameter hole portion 34 is generally flush with the inner circumferential surface of the side portion 32 of the bottom paper 8. In the battery 1, the volume of the gap formed between the separator 7 and the positive electrode 3 can be reduced because the end 39 of the separator 7 is not tapered or wrinkled. In the battery 1, the amount of the positive electrode 3 and the amount of the negative electrode 5 filled in the internal space 25 can be increased because the volume of the gap formed between the separator 7 and the positive electrode 3 is small. In the battery 1, the amount of the positive electrode 3 and the amount of the negative electrode 5 can be increased, so that the discharge capacity per unit volume of the battery 1 can be increased. The gap formed between the separator 7 and the positive electrode 3 may be filled with air or electrolyte. The internal resistance of the battery 1 may be increased by filling the gap with air or electrolyte. The small volume of the gap in the battery 1 can prevent the internal resistance from increasing. The reduced internal resistance of the battery 1 can improve the discharge performance.

[0028] [Battery manufacturing method] The battery manufacturing method of the embodiment is a method for manufacturing a battery 1. Fig. 3 is a flowchart showing the battery manufacturing method of the embodiment. In the battery manufacturing method, a granular positive electrode mixture made of electrolytic manganese dioxide, graphite, a binder, and an aqueous potassium hydroxide solution is prepared. After the granular positive electrode mixture is poured into a molding die, a predetermined molding pressure is applied to the granular positive electrode mixture to mold it, and a plurality of pellets are generated by the molding (step S1).

[0029] Next, as shown in FIG. 4, a partially processed positive electrode can 41 is prepared. FIG. 4 is a cross-sectional view showing a molding mix fitting step in which a positive electrode 3 is inserted into the inside of a partially processed positive electrode can 41. The partially processed positive electrode can 41 has a bottom portion 16 similar to the previously described positive electrode can 11, and the side portion 15 of the previously described positive electrode can 11 is replaced with another side portion 42. The side portion 42 is formed in a shape in which the beading portion 21 and the curl portion 22 of the previously described side portion 15 are not formed, and is formed into a cylindrical shape along the side of a cylinder. The partially processed positive electrode can 41 is formed so that the positive electrode can inner diameter d1 is equal to the positive electrode pellet outer diameter d2 or so that the positive electrode can inner diameter d1 is smaller than the positive electrode pellet outer diameter d2. The positive electrode can inner diameter d1 indicates the inner diameter of the side portion 42. The positive electrode pellet outer diameter d2 indicates the outer diameter of the three pellets.

[0030] The three pellets are inserted into partially processed positive electrode can 41 through opening 17 (step S2) and formed into positive electrode 3. As the three pellets are inserted into partially processed positive electrode can 41, partially processed positive electrode can 41 elastically deforms and applies an elastic force to positive electrode 3 such that the inner circumferential surface of side portion 42 comes into close contact with the outer circumferential surface of positive electrode 3. As the inner circumferential surface of side portion 42 comes into close contact with positive electrode 3, positive electrode 3 comes into electrical contact with partially processed positive electrode can 41.

[0031] After the positive electrode 3 is inserted into the partially processed positive electrode can 41, the partially processed positive electrode can 41 is processed so that a beading portion 21 is formed on the side surface portion 42 as shown in Fig. 3 (step S3). The beading portion 21 prevents the positive electrode 3 from slipping out of the partially processed positive electrode can 41 through the opening 17. Next, a sealing agent for the sealing portion is prepared. The sealing agent is applied to the sealing portion near the opening 17 on the inner circumferential surface of the side surface portion 42 of the partially processed positive electrode can 41 (step S4).

[0032] Next, a bottom paper separator member formed in a sheet shape is prepared. The bottom paper separator member is cut (step S5), formed into a cup shape (step S6), and formed into a bottom paper 8. The bottom paper 8 is inserted into the negative electrode filling hole 28 of the positive electrode 3 through the opening 17 so that the side portion 32 is not placed in the small inner diameter hole portion 34 of the positive electrode 3 but is placed in the large inner diameter hole portion 33 (step S7). Next, a sheet-shaped separator member is prepared. The separator member is cut (step S8-1), formed into a cylindrical shape (step S8-2), and generated into a separator 7. The separator 7 is inserted into the negative electrode filling hole 28 of the positive electrode 3 through the opening 17 so that the end 39 of the separator 7 is placed inside the side portion 32 of the bottom paper 8 (step S8-3).

[0033] Next, an electrolyte is prepared. After the separator 7 is inserted into the negative electrode filling hole 28 of the positive electrode 3, the electrolyte is injected into the inside of the positive electrode 3 through the opening 17 (step S9). By injecting the electrolyte into the negative electrode filling hole 28 of the positive electrode 3, the electrolyte impregnates the separator 7 and the positive electrode 3 (step S10). Next, the negative electrode 5 is prepared. The negative electrode 5 is injected into the inside of the separator 7 of the negative electrode filling hole 28 of the positive electrode 3 through the opening 17 (step S11). The bottom paper 8 is arranged such that the end 39 of the separator 7 is located inside the side portion 32, so that when the negative electrode 5 is injected into the inside of the separator 7, the negative electrode 5 can be prevented from leaking from the inside of the separator 7 through the gap between the separator 7 and the bottom paper 8 toward the bottom portion 16 of the partially processed positive electrode can 41, and the negative electrode 5 can be prevented from being electrically short-circuited to the partially processed positive electrode can 41.

[0034] Next, the current collector 6, the negative electrode terminal plate 12, and the sealing gasket 14 are prepared. The current collector 6, the negative electrode terminal plate 12, and the sealing gasket 14 are assembled and fixed to each other so that the current collector 6 is in electrical contact with the negative electrode terminal plate 12 and the edge of the negative electrode terminal plate 12 is covered with the sealing gasket 14, and a current collector is produced by this assembly. After the negative electrode 5 is injected inside the separator 7, the current collector is attached to the partially processed positive electrode can 41 so that the current collector 6 is embedded in the negative electrode 5 and the periphery of the sealing gasket 14 is in contact with the beading portion 21 (step S12). The current collector is placed at an appropriate position with respect to the partially processed positive electrode can 41 by the periphery of the sealing gasket 14 contacting the beading portion 21.

[0035] After the current collector is placed in an appropriate position relative to partially processed positive electrode can 41, partially processed positive electrode can 41 is crimped (step S13) and curled portion 22 is formed, thereby processing into positive electrode can 11 (step S14). Forming curled portion 22 fixes the current collector to positive electrode can 11 so that it does not come off from positive electrode can 11. Forming curled portion 22 also causes a gap formed between negative electrode terminal plate 12 and positive electrode can 11 to be sealed with sealing gasket 14, so that internal space 25 is hermetically sealed from the outside, and an unfinished battery is produced.

[0036] The weight of the unmanufactured battery is inspected (step S15), and after being stored in a predetermined atmosphere for a predetermined period of time (step S16), the open circuit voltage and the closed circuit voltage are inspected (step S17). Next, an insulating washer is prepared. The insulating washer is inserted into the opening 17 of the positive electrode can 11 of an unmanufactured battery that has not been found to have any defects during the inspection, and is disposed between the opening end 23 and the negative electrode terminal plate 12 (step S18). Next, a label is prepared. The performance and precautions of the battery 1 are printed on the label (step S19). The label is wrapped around the side portion 15 of the positive electrode can 11 of the unmanufactured battery, shrinks when heated, and is attached to the area of ​​the outer surface of the positive electrode can 11 excluding the positive electrode terminal portion 18 (step S20). The insulating washer is fixed to the positive electrode can 11 by attaching the label to the side portion 15 of the positive electrode can 11 of the unmanufactured battery. The unmanufactured batteries with the labels attached are inspected for appearance (step S21), and among the unmanufactured batteries, those for which no defects are found in the appearance inspection become manufactured batteries.

[0037] A number of battery samples are prepared so that the effect of the battery 1 of the embodiment can be evaluated. The battery samples include a comparative example battery and an example battery. The example battery is formed from the above-mentioned battery 1. The example battery is further designed so that the battery size is LR6 and the amount of the positive electrode 3 and the amount of the negative electrode 5 are as large as possible.

[0038] As shown in Fig. 5, the battery of the comparative example has the positive electrode 3 of the battery 1 described above replaced with another positive electrode 101, and the other parts are the same as the battery 1 described above. Fig. 5 is an enlarged cross-sectional view showing a part of the battery of the comparative example. The positive electrode 101 is formed in a cylindrical shape, and a negative electrode filling hole 102 penetrating the positive electrode 101 is formed inside the positive electrode 101. The negative electrode filling hole 102 is formed in a cylindrical shape, and the diameter of the negative electrode filling hole 102 does not change depending on the position in the longitudinal direction of the positive electrode 101 but is approximately constant.

[0039] The comparative battery is manufactured under the same manufacturing conditions as the example battery. That is, the comparative battery is manufactured so that the composition of the positive electrode 101 of the comparative battery is equal to the composition of the positive electrode 3 of the example battery, the composition of the negative electrode 5 of the comparative battery is equal to the composition of the negative electrode 5 of the example battery, and the battery size is LR6. The comparative battery is further designed so that the ratio of the amount of the positive electrode 101 to the amount of the negative electrode 5 of the comparative battery is equal to the ratio of the amount of the positive electrode 3 to the amount of the negative electrode 5 of the example battery, and the amount of the positive electrode 101 to the amount of the negative electrode 5 is as large as possible.

[0040] The inner diameter of the side portion 32 of the bottom paper 8 of the comparative battery is smaller than the inner diameter of the negative electrode filling hole 102. The edge 39 of the separator 7 of the comparative battery is narrowed and wrinkled because the inner diameter of the side portion 32 of the bottom paper 8 of the comparative battery is smaller than the inner diameter of the negative electrode filling hole 102. A gap 103 is formed between the negative electrode 5 and the positive electrode 101, where the negative electrode 5 is not filled, because the edge 39 of the separator 7 is narrowed or wrinkled. The gap 103 may be filled with air or electrolyte.

[0041] Table 1 shows a number of evaluation results corresponding to a number of battery samples. [Table 1] The plurality of evaluation results includes a plurality of fill amount comparison results, a plurality of first discharge test results, and a plurality of second discharge test results.

[0042] The multiple filling amount comparison results correspond to multiple battery samples. The filling amount comparison result corresponding to a certain battery sample among the multiple filling amount comparison results indicates a value calculated by dividing the sum of the weight of the positive electrode 3 or positive electrode 101 and the weight of the negative electrode 5 provided in that battery sample by the sum of the weight of the positive electrode 101 and the weight of the negative electrode 5 provided in the comparative battery, and multiplying the value by 100. The multiple filling amount comparison results indicate that the larger the value of the battery sample, the larger the filling amount of the positive electrode active material and the negative electrode active material filled in.

[0043] Among the multiple filling amount comparison results, the filling amount comparison result corresponding to the battery of the comparative example shows 100, and the filling amount comparison result corresponding to the battery of the example shows 100.5. The multiple filling amount comparison results show that the filling amount between the positive electrode 3 and the negative electrode 5 of the battery of the example is larger than the filling amount between the positive electrode 101 and the negative electrode 5 of the battery of the comparative example. The multiple filling amount comparison results show that the filling amount between the positive electrode 3 and the negative electrode 5 of the battery of the example can be increased by the amount that the gap formed between the positive electrode 3 and the separator 7 of the battery of the example is smaller than the gap formed between the positive electrode 101 and the separator 7 of the battery of the comparative example.

[0044] The multiple first discharge test results correspond to multiple battery samples. The first discharge test result corresponding to a certain battery sample among the multiple first discharge test results indicates a result derived by performing a first discharge test on the certain battery sample. In the first discharge test performed on a certain battery sample, a 5-minute discharge pattern is repeatedly performed every hour until the battery voltage of the certain battery sample becomes smaller than the end voltage of 1.05 V, and a discharge time is derived. In the 5-minute discharge pattern, a 30-second discharge pattern is repeatedly performed 10 times. The 30-second discharge pattern is formed of a 2-second discharge period and a 28-second discharge period. In the 2-second discharge period, the certain battery sample is electrically connected to a load of 1500 mW, and the certain battery sample is pulse-discharged. The 28-second discharge period starts immediately after the 2-second discharge period ends. In the 28-second discharge period, the certain battery sample is electrically connected to a load of 650 mW for 28 seconds, and the certain battery sample is pulse-discharged. During the 55 minute period outside of the 5 minute discharge pattern of the hour, the battery specimen is electrically isolated from the load so that the battery specimen is not discharged.

[0045] The discharge time indicates the time that the battery sample discharged before the battery voltage of the battery sample became smaller than the final voltage of 1.05 V. The first discharge test result corresponding to a certain battery sample among the multiple first discharge test results indicates a value obtained by dividing the average discharge time of multiple batteries fabricated as that battery sample by the average discharge time of multiple batteries fabricated as comparative example batteries, and multiplying the result by 100. The multiple first discharge test results indicate that a battery sample with a larger first discharge test result has better discharge performance under a heavy load.

[0046] Among the multiple first discharge test results, the first discharge test result corresponding to the battery of the comparative example is 100, and the first discharge test result corresponding to the battery of the example is 120. The multiple first discharge test results show that the first discharge test result of the battery of the example is greater than the first discharge test result of the battery of the comparative example, and show that the discharge performance of the battery of the example under heavy load is better than the discharge performance of the battery of the comparative example under heavy load. It is believed that the reason why the discharge performance of the battery of the example is better under heavy load is because the gap formed inside the battery of the example is small, which reduces the internal resistance of the battery of the example.

[0047] A second discharge test result corresponding to a certain battery sample among the multiple second discharge test results is derived by performing a second discharge test on the battery sample. In the second discharge test performed on a certain battery sample, a daily discharge pattern is repeatedly performed every day until the battery voltage of the battery sample reaches an end voltage of 0.9V, and a discharge time is derived. The daily discharge pattern is formed of a one-hour discharge period and a rest period. In the one-hour discharge period, the battery sample is electrically connected to a load so that the battery sample is discharged at 100mA. The rest period is formed of a period other than the one-hour discharge period of the daily discharge pattern, and in the rest period, the battery sample is electrically insulated from the load so that the battery sample is not discharged. The discharge time indicates the time that the battery sample was discharging before the battery voltage of the battery sample reached an end voltage of 0.9V.

[0048] In the second discharge test performed on a certain battery sample, an average discharge time of the battery sample is further derived. The average discharge time of the battery sample indicates an average of a plurality of discharge times derived for a plurality of batteries fabricated as the battery sample. A second discharge test result corresponding to a certain battery sample among the plurality of second discharge test results indicates a value obtained by dividing the average discharge time of the battery sample by the average discharge time of the comparative battery, and multiplying the result by 100. The plurality of second discharge test results indicate that a battery sample corresponding to a second discharge test result showing a larger value has better light-load discharge performance.

[0049] Among the multiple second discharge test results, the second discharge test result corresponding to the battery of the comparative example shows 100, and the second discharge test result corresponding to the battery of the example shows 102. The multiple second discharge test results show that the second discharge test result of the battery of the example is greater than the second discharge test result of the battery of the comparative example, and show that the discharge performance of the battery of the example under light load is better than the discharge performance of the battery of the comparative example under light load. It is believed that the good discharge performance of the battery of the example under light load is due to the large amounts of positive electrode active material and negative electrode active material contained in the battery of the example.

[0050] 6 is a flowchart showing a battery manufacturing method of the comparative example. The battery manufacturing method of the comparative example replaces steps S1 to S2 of the battery manufacturing method of the previously described embodiment with other steps, and includes steps S3 to S21, similar to the battery manufacturing method of the previously described embodiment. In the battery manufacturing method of the comparative example, a granular positive electrode mixture is prepared. After the granular positive electrode mixture is poured into a molding die, a predetermined molding pressure is applied to the granular positive electrode mixture to mold it, and a plurality of pellets are generated by the molding (step S101).

[0051] Next, as shown in Fig. 7, a partially processed positive electrode can 41 is prepared. Fig. 7 is a cross-sectional view showing an internal can pressurization step for forming a positive electrode 3 inside the partially processed positive electrode can 41 in a battery manufacturing method of a comparative example. The multiple pellets 111 are formed such that the positive electrode pellet outer diameter d3 is smaller than the positive electrode can inner diameter d1. The positive electrode pellet outer diameter d3 indicates the outer diameter of the multiple pellets 111. The multiple pellets 111 are inserted into the partially processed positive electrode can 41 through the opening 17 (step S102).

[0052] After the multiple pellets 111 are inserted into the inside of the partially processed positive electrode can 41, the multiple pellets 111 are formed into the positive electrode 3 inside the partially processed positive electrode can 41 by using an internal can pressurizing device. That is, the internal can pressurizing device includes a core rod 112 and an upper punch 113. The core rod 112 is formed in a roughly cylindrical shape, and a large outer diameter core rod portion 114 is formed at the lower end of the core rod 112. The outer diameter of the large outer diameter core rod portion 114 is larger than the outer diameter of a portion of the core rod 112 that is different from the large outer diameter core rod portion 114.

[0053] The can internal pressurizing device pressurizes the upper ends 115 of the pellets 111 using the upper punch 113 with the core rod 112 inserted in the through holes of the pellets 111 (step S103). The upper ends 115 of the pellets 111 are pressed by the upper punch 113, so that the pellets 111 are molded into the positive electrode 3. That is, the positive electrode 3 is formed with a large inner diameter hole portion 33 that fits into the large outer diameter core rod portion 114, and a small inner diameter hole portion 34 that fits into a portion of the core rod 112 where the large outer diameter core rod portion 114 is not formed. By molding the positive electrode 3 in this manner, it is further brought into close contact with the inner circumferential surface of the side portion 42 of the positive electrode 3, and the positive electrode 3 is in electrical contact with the positive electrode can 41 in the middle of processing.

[0054] In the in-can pressurizing device, after the positive electrode 3 is formed, the upper punch 113 and the core rod 112 are pulled out from the partially processed positive electrode can 41. That is, the in-can pressurizing device is designed to pull out the core rod 112 from the partially processed positive electrode can 41 without the large outer diameter core rod portion 114 of the core rod 112 getting caught on the positive electrode 3. As an example of such a design, after the multiple pellets 111 are formed into the positive electrode 3, the core rod 112 is disassembled into multiple parts, and the multiple parts are pulled out one by one from the partially processed positive electrode can 41.

[0055] After the internal can pressurization process is performed in which the positive electrode 3 is formed inside the partially processed positive electrode can 41, steps similar to steps S3 to S21 of the battery manufacturing method of the embodiment described above are performed as shown in FIG. 6 to produce the battery 1 product.

[0056] In the battery manufacturing method of the comparative example, it is necessary to devise a way to pull out the core rod 112 from the partially processed positive electrode can 41 without the large outer diameter core rod portion 114 getting caught on the positive electrode 3, which makes it difficult to form the positive electrode 3 and may increase manufacturing costs. The battery manufacturing method of the embodiment described above makes it easier to manufacture the battery 1 than the battery manufacturing method of the comparative example, and can reduce the manufacturing costs for manufacturing the battery 1.

[0057] [Effects of Battery 1 of the Embodiment] The battery 1 of the embodiment includes a positive electrode can 11, a positive electrode 3, a negative electrode 5, a separator 7, and a bottom paper 8. The positive electrode 3 is disposed inside the positive electrode can 11. The negative electrode 5 is disposed in a negative electrode filling hole 28 formed in the positive electrode 3. The separator 7 is formed in a cylindrical shape and disposed between the negative electrode 5 and the positive electrode 3. The bottom paper 8 includes a side portion 32 disposed between the separator 7 and the positive electrode 3, and a bottom portion 31 surrounded by the side portion 32. The bottom portion 31 is disposed between the negative electrode 5 and the positive electrode can 11. The inner diameter of the large inner diameter hole portion 33 of the negative electrode filling hole 28 in which the bottom paper 8 is disposed is larger than the inner diameter of the small inner diameter hole portion 34 of the negative electrode filling hole 28 in which the bottom paper 8 is not disposed.

[0058] At this time, in the battery 1 of the embodiment, the degree to which the edge 39 of the separator 7 is narrowed can be reduced, the degree to which the edge 39 of the separator 7 is wrinkled can be reduced, and the gap formed between the separator 7 and the positive electrode 3 can be reduced. In the battery 1 of the embodiment, since the gap formed between the separator 7 and the positive electrode 3 is small, the filling amount between the positive electrode 3 and the negative electrode 5 can be increased accordingly, and the internal resistance can be reduced, thereby improving the discharge performance.

[0059] Incidentally, the positive electrode 3 of the battery 1 in the above-described embodiment is formed so that the inner peripheral surface of the small inner diameter hole portion 34 is generally flush with the inner peripheral surface of the side portion 32 of the bottom paper 8, but the inner diameter of the side portion 32 of the bottom paper 8 may be formed so that it is smaller than the inner diameter of the small inner diameter hole portion 34. Even when the battery 1 is formed in this manner, a step is formed at the boundary between the large inner diameter hole portion 33 and the small inner diameter hole portion 34, so that the degree to which the end 39 of the separator 7 narrows and the degree to which the end 39 of the separator 7 wrinkles can be reduced. In the battery 1, the degree to which the end 39 of the separator 7 narrows and the degree to which the end 39 of the separator 7 wrinkles can be reduced, so that the gap formed between the separator 7 and the positive electrode 3 can be reduced, and accordingly, the amount of filling between the positive electrode 3 and the negative electrode 5 can be increased and the internal resistance can be reduced, thereby improving the discharge performance.

[0060] The positive electrode 3 of the battery 1 of the embodiment includes a small inner diameter positive electrode portion 37 in which a small inner diameter hole portion 34 is formed, and a large inner diameter positive electrode portion 36 in which a large inner diameter hole portion 33 is formed. The large inner diameter positive electrode portion 36 is connected to the small inner diameter positive electrode portion 37 and is formed integrally with the small inner diameter positive electrode portion 37. In this case, the battery 1 of the embodiment is easily produced by, for example, replacing one pellet on the side of the bottom portion 16 of the positive electrode can 11 among the multiple pellets forming the positive electrode 101 of the battery of the comparative example described above with another pellet.

[0061] The battery manufacturing method of the embodiment is a method for manufacturing the battery 1 of the embodiment, and includes preparing a positive electrode 3 and a positive electrode can 11, and inserting the positive electrode 3 into the positive electrode can 11. The outer diameter of the positive electrode 3 is larger than or equal to the inner diameter of the positive electrode can 11 before the positive electrode 3 is inserted into the positive electrode can 11. According to the battery manufacturing method of the embodiment, the battery 1 can be manufactured more easily than other battery manufacturing methods in which the positive electrode 3 is formed by an in-can pressurization method, and the manufacturing cost of the battery 1 can be reduced.

[0062] Incidentally, the inner diameter of the large inner diameter hole portion 33 of the battery 1 in the above-described embodiment is generally constant and does not change depending on the position in the longitudinal direction of the negative electrode filling hole 28, but may be larger toward the small inner diameter hole portion 34. The thickness of the side portion 32 may be thicker as it moves away from the bottom portion 31 due to the wrinkles in the side portion 32. In the battery 1, by forming the large inner diameter hole portion 33 in this manner, even when the thickness of the side portion 32 of the bottom paper 8 increases as it moves away from the bottom portion 31, the inner surface of the small inner diameter hole portion 34 of the positive electrode 3 can be flush with the inner surface of the side portion 32 of the bottom paper 8, and the volume of the gap formed between the side portion 32 and the inner surface of the large inner diameter hole portion 33 of the positive electrode 3 can be reduced. At this time, the battery 1 can reduce the degree to which the end 39 of the separator 7 narrows and the degree to which the end 39 of the separator 7 wrinkles, and the volume of the gap formed between the separator 7 and the positive electrode 3 can be reduced. Therefore, by forming the large inner diameter hole portion 33 in this manner, the battery 1 can further suppress the decrease in discharge performance compared to the battery 1 of the above-described embodiment.

[0063] In the battery 1 of the embodiment described above, a portion of the small inner diameter hole portion 34 and the large inner diameter hole portion 33 are formed in one pellet 35 of the three pellets formed in the positive electrode 3, but as shown in FIG. 8, the small inner diameter hole portion 34 may not be formed in the large inner diameter positive electrode pellet 52 in which the large inner diameter hole portion 33 is formed among the multiple pellets formed in the positive electrode 3. FIG. 8 is an enlarged cross-sectional view showing a battery of a modified example. In the battery of the modified example, the positive electrode 3 of the battery 1 of the embodiment described above is replaced with another positive electrode 30, and the other parts are the same as the battery 1 of the embodiment described above. The positive electrode 30 is made of electrolytic manganese dioxide MnO, like the positive electrode 3 described above. 2 The negative electrode filling hole 28 contains the graphite C, an aqueous potassium hydroxide solution, and a binder, and is formed with a large inner diameter hole portion 33 and a small inner diameter hole portion 34.

[0064] The positive electrode 30 includes a plurality of small inner diameter positive electrode pellets 51 and a large inner diameter positive electrode pellet 52. The plurality of small inner diameter positive electrode pellets 51 and the large inner diameter positive electrode pellets 52 are separate from each other and formed in a cylindrical shape. The plurality of small inner diameter positive electrode pellets 51 and the large inner diameter positive electrode pellets 52 are arranged so that a plurality of through holes formed in the plurality of small inner diameter positive electrode pellets 51 and the large inner diameter positive electrode pellets 52, respectively, are connected. The plurality of small inner diameter positive electrode pellets 51 do not have a large inner diameter hole portion 33, but have a small inner diameter hole portion 34. The large inner diameter positive electrode pellet 52 does not have a small inner diameter hole portion 34, but have a large inner diameter hole portion 33.

[0065] In the battery of the modified example, similarly to the battery 1 of the embodiment described above, the degree to which the end 39 of the separator 7 narrows and the degree to which the end 39 of the separator 7 wrinkles can be reduced, and the gap formed between the separator 7 and the positive electrode 30 can be reduced. In the battery of the modified example, similarly to the battery 1 of the embodiment, the small gap formed between the separator 7 and the positive electrode 30 can increase the filling amount between the positive electrode 30 and the negative electrode 5 and reduce the internal resistance, thereby improving the discharge performance.

[0066] The pellet 35 described above has a complex shape, and in particular, when the inner diameter of the large inner diameter hole portion 33 increases as it approaches the small inner diameter hole portion 34, some ingenuity is required to remove the pellet 35 from the mold used to mold the pellet 35, which may increase the manufacturing cost. That is, the multiple small inner diameter positive electrode pellets 51 and the large inner diameter positive electrode pellet 52 have a simpler shape than the pellet 35 described above, and are easily manufactured even when the inner diameter of the large inner diameter hole portion 33 increases as it approaches the small inner diameter hole portion 34. Therefore, the battery of the modified example can be manufactured more easily and the manufacturing cost can be reduced compared to the battery 1 of the embodiment described above.

[0067] Although the embodiments have been described above, the embodiments are not limited to the above. 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 appropriately combined. Furthermore, at least one of various omissions, substitutions, and modifications of the components can be made without departing from the gist of the embodiments. [Explanation of symbols]

[0068] 1:Battery 3: Positive electrode 5: Negative electrode 7: Separator 8: Bottom paper 11: Positive electrode can 25:Interior space 28: Negative electrode filling hole 31: Bottom part 32: Side part 33: Large inner diameter hole 34: Small inner diameter hole part 35: Pellet 36: Large inner diameter positive electrode part 37: Small inner diameter positive electrode part 39: Edge

Claims

1. A positive electrode can; a positive electrode disposed inside the positive electrode can; a negative electrode disposed in a negative electrode filling hole formed in the positive electrode; a separator formed in a cylindrical shape and disposed between the negative electrode and the positive electrode; A base paper is provided. The bottom paper is a side portion disposed between the separator and the positive electrode; a bottom portion surrounded by said side portions; the bottom portion is disposed between the negative electrode and the positive electrode can; The diameter of the large inner diameter hole portion of the negative electrode filling hole where the bottom paper is disposed is larger than the diameter of the small inner diameter hole portion of the negative electrode filling hole where the bottom paper is not disposed. battery.

2. The positive electrode is a small inner diameter positive electrode portion in which the small inner diameter hole portion is formed; a large inner diameter positive electrode portion in which the large inner diameter hole portion is formed; The large inner diameter positive electrode portion is integrally formed with the small inner diameter positive electrode portion.

10. The battery of claim 1.

3. The positive electrode is a small inner diameter positive electrode pellet in which the large inner diameter hole portion is not formed and the small inner diameter hole portion is formed; a large inner diameter positive electrode pellet in which the small inner diameter hole portion is not formed and the large inner diameter hole portion is formed, The large inner diameter positive electrode pellet is separate from the small inner diameter positive electrode pellet.

10. The battery of claim 1.

4. The positive electrode is formed such that the diameter of the small inner diameter hole portion increases toward the large inner diameter hole portion.

10. The battery of claim 1.

5. The battery of claim 1 A battery manufacturing method comprising the steps of: providing the positive electrode and the positive electrode can; and inserting the positive electrode into the positive electrode can; The outer diameter of the positive electrode is greater than or equal to the inner diameter of the positive electrode can before the positive electrode is inserted into the positive electrode can. Battery manufacturing method.

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