Battery and method for manufacturing a battery

Abstract

To improve a discharge performance.SOLUTION: A battery 1 comprises: a positive electrode can 11; a positive electrode 3 formed in a pipe shape and arranged in an inner part of the positive electrode can 11; a negative electrode 5 arranged in the inner part of the positive electrode 3; and a separator 7. The separator 7 comprises: a side surface member 25 formed by a non-woven fabric; and a bottom surface member 26 that is formed of a hot melt resin which more hardly passes an ion than the non-woven fabric. The side surface member 25 is sandwiched between the negative electrode 5 and the positive electrode 3. The bottom surface member 26 is sandwiched between the negative electrode 5 and the positive electrode can 11. The bottom surface member 26 is bonded to the side surface member 25 without making the non-woven fabric sandwiched between the negative electrode 5 and the positive electrode can 11, and making the hot melt resin sandwiched between the negative electrode 5 and the positive electrode 3.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] An alkaline dry battery is known in which a positive electrode and a negative electrode stored inside a positive electrode can are separated by a bottomed cylindrical separator. The bottom part of the separator that separates the negative electrode from the positive electrode can may contain a hot melt resin so as not to be penetrated by dendrites growing from the negative electrode (Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the injection accuracy of the hot melt resin is poor, it is necessary to inject more hot melt resin so that no closing defect occurs on the bottom surface of the separator. In an alkaline dry battery, when more hot melt resin is injected, the hot melt resin may impregnate the side surface portion of the separator that separates the negative electrode from the positive electrode, or the internal volume of the negative electrode may be reduced, resulting in a decrease in discharge performance.

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

Means for Solving the Problems

[0006] A battery according to one aspect of the present disclosure includes a positive electrode can, a positive electrode formed in a tubular shape and disposed inside the positive electrode can, a negative electrode disposed inside the positive electrode, and a separator. The separator includes a side member formed of a first material and Becomes liquid when heated an insulating Hot melt resin bottom member formed therefrom. The side member is sandwiched between the negative electrode and the positive electrode. The bottom member is sandwiched between the negative electrode and the positive electrode can The bottom surface portion that does not contact the positive electrode among them . The bottom member is joined to the side member so that the first material is not sandwiched between the negative electrode and Bottom surface portion and so that Hot melt resin is not sandwiched between the negative electrode and the positive electrode. [Advantages of the Invention]

[0007] The disclosed battery and battery manufacturing method can improve discharge performance. [Brief Description of the Drawings]

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[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 technology of the present disclosure is not limited by the following description. Also, in the following description, the same reference numerals are given to the same components, and overlapping descriptions are omitted.

[0010] [Battery 1 of the Embodiment] As shown in FIG. 1, the battery 1 of the embodiment is a so-called alkaline dry battery, and includes a battery case 2, a positive electrode 3, a negative electrode 5, a current collector rod 6, and a separator 7. 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 formed of a conductor exemplified by a metal. The positive electrode can 11 is formed in a bottomed cylindrical shape and includes a side surface portion 15 and a bottom surface portion 16. The side surface portion 15 is formed of a bent plate along the side surface of the cylinder. The bottom surface portion 16 is disposed along one bottom surface of the cylinder. The bottom surface portion 16 is integrally connected to the side surface portion 15 such that the edge of the bottom surface portion 16 is adjacent to one end of the bottom surface portion 16.

[0011] The bottom surface portion 16 is formed with irregularities, and a positive electrode terminal portion 17 is formed at the center of the bottom surface portion 16. The positive electrode terminal portion 17 is formed to protrude from the inside to the outside of the positive electrode can 11. An opening 18 is formed in the positive electrode can 11. The opening 18 is formed at a portion of the side surface portion 15 corresponding to the other bottom surface of the cylinder. The inside of the positive electrode can 11 is connected to the outside of the positive electrode can 11 through the opening 18. A beading portion 21 is formed on the side surface portion 15. The beading portion 21 is formed in the vicinity of the opening 18 in the side surface portion 15. The beading portion 21 is formed such that a part of the inner diameter in the vicinity of the opening 18 in the side surface portion 15 becomes smaller.

[0012] The negative electrode terminal plate 12 is formed of a conductor exemplified by metal and is generally formed in a disk shape. The negative electrode terminal plate 12 is arranged along the other bottom surface of the cylinder so as to close the opening 18 of the positive electrode can 11. Inside the battery case 2, by the negative electrode terminal plate 12 closing the opening 18, an internal space 23 surrounded by the positive electrode can 11 and the negative electrode terminal plate 12 is formed.

[0013] The sealing gasket 14 is formed of an insulator exemplified by resin and is generally formed in a ring shape. The sealing gasket 14 surrounds the edge of the negative electrode terminal plate 12 and is arranged at the opening 18 of the positive electrode can 11. The sealing gasket 14 is sandwiched between the edge of the negative electrode terminal plate 12 and 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. The negative electrode terminal plate 12 is fixed to the positive electrode can 11 via the sealing gasket 14 by the sealing gasket 14 being sandwiched between the edge of the negative electrode terminal plate 12 and the positive electrode can 11. The negative electrode terminal plate 12 is electrically insulated from the positive electrode can 11 via the sealing gasket 14 by the sealing gasket 14 being sandwiched between the edge of the negative electrode terminal plate 12 and the positive electrode can 11.

[0014] The positive electrode 3 is formed of a positive electrode active material, a binder, and an aqueous potassium hydroxide solution. The positive electrode active material contains manganese dioxide MnO 2 and graphite C. The binder contains, for example, a polymer compound and adheres the powders formed from the positive electrode active material to each other to form a solid. The positive electrode 3 is formed in a tubular shape and is arranged in the internal space 23 of the battery case 2. The positive electrode 3 is in close contact with the inner peripheral surface of the side portion 15 of the positive electrode can 11 so that the positive electrode active material is electrically connected to the positive electrode can 11. The negative electrode 5 is formed of a negative electrode active material and is formed in a gel shape. The negative electrode active material contains zinc alloy powder and an aqueous potassium hydroxide solution. The negative electrode 5 is arranged inside the positive electrode 3 in the internal space 23 of the battery case 2.

[0015] The current collector rod 6 is formed of a conductor and is rod-shaped. The current collector rod 6 is disposed in the internal space 23 along the central axis of the cylinder along which the side surface portion 15 extends. The current collector rod 6 is further embedded in the negative electrode 5 so as to be electrically connected to the negative electrode active material of the negative electrode 5. The current collector rod 6 further penetrates the center of the sealing gasket 14. One end of the current collector rod 6 is joined to the negative electrode terminal plate 12 such that the current collector rod 6 is electrically connected to the negative electrode terminal plate 12.

[0016] The separator 7 is formed in a hollow cylindrical shape and includes a side member 25 and a bottom member 26. The side member 25 is formed of a non-woven fabric formed of an insulator exemplified by vinylon, pulp, etc. Note that the side member 25 may be formed of another insulator having good ion conductivity. The side member 25 is formed in a tubular shape and forms a portion corresponding to the side surface of the cylinder formed by the separator 7. The side member 25 is disposed between the positive electrode 3 and the negative electrode 5 in the internal space 23 and separates the positive electrode 3 and the negative electrode 5.

[0017] The bottom member 26 is formed of a hot-melt resin. The hot-melt resin is mainly formed of a thermoplastic resin that is solid at normal temperature and becomes liquid upon heating. The hot-melt resin has resistance to alkali. Further, the hot-melt resin is less permeable to ions compared to the material forming the side member 25, that is, the ion conductivity of the solid hot-melt resin is worse than the ion conductivity of the material forming the side member 25. Note that the bottom member 26 can also be formed of a material different from the hot-melt resin. The material has resistance to alkali and is less permeable to ions compared to the material forming the side member 25, that is, the ion conductivity of the material is worse than the ion conductivity of the material forming the side member 25. Examples of such materials include polyethylene, polypropylene, and vinyl chloride. The bottom member 26 is formed in a circular sheet shape and forms a portion corresponding to one bottom surface of the cylinder formed by the separator 7. The bottom member 26 is disposed between the negative electrode 5 and the bottom surface portion 16 of the positive electrode can 11 in the internal space 23 and separates the bottom of the positive electrode can 11 from the negative electrode 5. The bottom member 26 is joined to the side member 25 so that no gap is formed between the side member 25 and the bottom member 26. In FIG. 1, the bottom member 26 is formed flat and a gap is formed between the bottom member 26 of the separator 7 and the bottom surface portion 16 of the positive electrode can 11, but it may be bent and in close contact with the bottom surface portion 16 so that no gap is formed between the bottom member 26 and the bottom surface portion 16.

[0018] The battery 1 further includes an electrolytic solution. The electrolytic solution is formed from an aqueous solution containing potassium hydroxide KOH. The electrolytic solution is disposed in the internal space 23 so that the positive electrode 3 and the negative electrode 5 are immersed in the electrolytic solution, penetrates into the separator 7, and penetrates into the positive electrode 3.

[0019] [Battery Manufacturing Method of Embodiment] The battery manufacturing method of the embodiment includes the production of a separator and the assembly of a battery. In the production of the separator, a side member 25 to which a bottom member 26 is not joined is prepared. FIG. 2 is a perspective view showing the side member 25 to which the bottom member 26 is not joined. An opening 32 is formed at one end 31 of the side member 25, and an end face 33 is formed. The inside of the side member 25 is connected to the outside of the side member 25 through the opening 32. The end face 33 is formed substantially flat and along one plane.

[0020] In the production of the separator, further, as shown in FIG. 3, a hot-melt resin 34 is prepared. FIG. 3 is a side view showing the side member 25 during the formation of the separator 7. The hot-melt resin 34 is heated to be in a liquid state and stored in a container 35. The side member 25 is disposed on the hot-melt resin 34 such that the entire end face 33 is in contact with the hot-melt resin 34 and the surface of the side member 25 different from the end face 33 is not in contact with the hot-melt resin 34 as much as possible.

[0021] After the entire end face 33 of the side member 25 comes into contact with the hot-melt resin 34, the side member 25 is separated from the hot-melt resin 34. A part of the hot-melt resin 34 is formed into a film that closes the opening 32 of the side member 25 when the side member 25 is separated from the hot-melt resin 34. The film is cooled and solidified when the side member 25 is separated from the hot-melt resin 34, and is formed on the bottom member 26 as shown in FIG. 4. FIG. 4 is a perspective view showing the separator 7.

[0022] Note that when the bottom member 26 of the separator 7 is formed using an insulator different from the hot-melt resin, the bottom member 26 is produced by other processes. In that process, for example, a disk-shaped base paper is cut out from a sheet made of an insulator, and the base paper is adhered to the side member 25 so as to close the opening 32, and the separator 7 is produced.

[0023] In the battery assembly, a positive electrode 3 and a positive electrode can 11 before the formation of the beading portion 21 are prepared. The positive electrode 3 is inserted into the positive electrode can 11 such that the outer peripheral surface of the positive electrode 3 contacts the inner peripheral surface of the positive electrode can 11. After the positive electrode 3 is inserted into the positive electrode can 11, the positive electrode can 11 is processed so that the beading portion 21 is formed at the opening 18 of the positive electrode can 11. The positive electrode 3 is prevented from coming out of the positive electrode can 11 by the formation of the beading portion 21 on the positive electrode can 11. After the beading portion 21 is formed on the positive electrode can 11, as shown in FIG. 5, a separator 7 is inserted inside the positive electrode 3. FIG. 5 is a cross-sectional view showing the separator 7 inserted inside the positive electrode 3.

[0024] After the separator 7 is inserted inside the positive electrode 3, air is injected inside the separator 7 at a predetermined pressure. The bottom member 26 is pressurized toward the bottom surface portion 16 of the positive electrode can 11 by the injection of air inside the separator 7, bends, and adheres to the bottom surface portion 16 as shown in FIG. 6. FIG. 6 is a cross-sectional view showing the bottom member 26 when air is introduced inside the separator 7. Note that, in the battery assembly, the step of pressurizing the bottom member 26 toward the bottom surface portion 16 may be omitted.

[0025] After the separator 7 is inserted inside the positive electrode 3, an electrolytic solution is injected inside the positive electrode 3 and allowed to soak into the separator 7. At this time, the electrolytic solution also soaks into the positive electrode 3. In the assembly of the battery, further, a gel-like negative electrode 5 is prepared using zinc alloy powder and an aqueous potassium hydroxide solution, and a current collector rod 6, a negative electrode terminal plate 12, and a sealing gasket 14 are prepared. After the electrolytic solution has soaked into the separator 7 and the positive electrode 3, the negative electrode 5 is injected inside the separator 7 to a predetermined height. After the negative electrode 5 is injected, the current collector rod 6 joined to the negative electrode terminal plate 12 is embedded in the negative electrode 5, and the current collector rod 6, the negative electrode terminal plate 12, and the sealing gasket 14 are attached to the positive electrode can 11 so that the negative electrode terminal plate 12 and the sealing gasket 14 close the opening 18. After the current collector rod 6, the negative electrode terminal plate 12, and the sealing gasket 14 are attached to the positive electrode can 11, the portion near the opening 18 of the positive electrode can 11 is caulked so that the gap formed between the edge of the negative electrode terminal plate 12 and the positive electrode can 11 is sealed by the sealing gasket 14. By caulking the positive electrode can 11, the sealing gasket 14 is deformed, the current collector rod 6, the negative electrode terminal plate 12, and the sealing gasket 14 are fixed to the positive electrode can 11, the internal space 23 is sealed from the outside, and the battery 1 is manufactured.

[0026] According to such a battery manufacturing method, the separator 7 can be easily and appropriately manufactured such that the thickness of the bottom member 26 becomes equal to a predetermined value and the bottom member 26 is appropriately joined to the side member 25.

[0027] [Evaluation Test of Battery 1] To confirm the effects of the battery 1 of the embodiment, a plurality of battery samples are manufactured, and a plurality of evaluation tests are performed on each of the plurality of battery samples. Table 1 shows a plurality of manufacturing conditions corresponding to the plurality of battery samples and a plurality of evaluation results.

Table 1

[0028] The plurality of battery samples include the battery of Comparative Example 1, the battery of Comparative Example 2, the battery of Comparative Example 3, the battery of Comparative Example 4, the battery of Example 1, the battery of Example 2, the battery of Example 3, the battery of Example 4, the battery of Example 5, the battery of Example 6, and the battery of Example 7. Each of the plurality of battery samples includes a plurality of batteries manufactured based on the battery manufacturing method described above.

[0029] The plurality of battery samples are manufactured such that their manufacturing conditions are different from each other. The manufacturing conditions are indicated by the separator manufacturing method and the bottom thickness. The separator manufacturing method corresponding to a certain battery sample indicates the method of manufacturing the separator provided in that battery sample. The bottom thickness corresponding to a certain battery sample indicates the thickness of the portion corresponding to the bottom member 26 in that battery sample.

[0030] The plurality of battery samples are manufactured in the same manner as each other except that their manufacturing conditions are different from each other. That is, for the plurality of battery samples, the positive electrode 3, the current collector rod 6, the positive electrode can 11, the negative electrode terminal plate 12, and the sealing gasket 14 are manufactured such that the battery size becomes LR6. In the assembly of the battery, further, the negative electrode 5 is injected in an amount such that the negative electrode 5 can be injected into the separator 7.

[0031] As shown in FIG. 7, in the battery of Comparative Example 1, the separator 7 of the aforementioned battery 1 is replaced with another separator 101. FIG. 7 is a schematic cross-sectional view showing the separator 101 of the battery of Comparative Example 1. The separator 101 is manufactured by a method different from the manufacture of the separator in the aforementioned battery manufacturing method, and includes a side member 102 and a bottom portion 103. The side member 102 is formed from a part of a tubular nonwoven fabric member produced by double-winding a nonwoven fabric with a thickness of 120 μm made of vinylon, pulp, and vinylon binder fibers. The bottom portion 103 is formed from the remaining part of the nonwoven fabric member and a hot melt resin, is formed in a disc shape, and closes the opening at one end of the side member 102. That is, the bottom portion 103 is formed by bending one end of the nonwoven fabric member inward and heat-sealing the bent portion using a hot melt resin. The bottom portion 103 is relatively thick because a part of the nonwoven fabric member is heat-sealed. The bottom thickness of the battery of Comparative Example 1 indicates the thickness of the bottom portion 103 and shows 1.0 mm.

[0032] In the battery of Comparative Example 2, the separator 7 of the aforementioned Battery 1 is replaced with another separator. The separator is manufactured by a method different from the manufacturing method of the separator in the aforementioned battery manufacturing method, and is manufactured using two strip-shaped nonwoven fabrics. The two strip-shaped nonwoven fabrics are overlapped at their centers along two straight lines where the two strip-shaped nonwoven fabrics are orthogonal. The portion corresponding to the bottom member 26 among the separators of the battery of Comparative Example 2 is formed from the overlapped portion of the two strip-shaped nonwoven fabrics. The portion corresponding to the side member 25 among the separators of the battery of Comparative Example 2 is formed from the non-overlapped portion of the two strip-shaped nonwoven fabrics. The portion corresponding to the side member 25 among the separators of the battery of Comparative Example 2 includes the portion where the nonwoven fabrics overlap. The ionic conductivity of the overlapping portion of the nonwoven fabrics is worse than that of the non-overlapping portion of the nonwoven fabrics, and ions pass through the overlapping portion of the nonwoven fabrics with more difficulty compared to the non-overlapping portion. The portion corresponding to the aforementioned side member 25 among the separators of the battery of Comparative Example 2 includes the portion where the nonwoven fabrics overlap. The bottom thickness of the battery of Comparative Example 2 indicates the thickness of the overlapping portion of the two strip-shaped nonwoven fabrics and shows 0.24 mm.

[0033] As shown in FIG. 8, in the battery of Comparative Example 3, the separator 7 of the aforementioned Battery 1 is replaced with another separator 111. FIG. 8 is a schematic cross-sectional view showing the separator 111 of the battery of Comparative Example 3. The separator 111 includes a side member 25 and a bottom member 113. That is, the separator 111 is manufactured by a method different from the manufacturing method of the separator in the aforementioned battery manufacturing method, the bottom member 26 of the aforementioned separator 7 is replaced with another bottom member 113, and the other parts are the same as the aforementioned separator 7. The bottom member 113 is formed from a base paper formed from the same nonwoven fabric as the nonwoven fabric in which the side member 25 is formed. A part of the bottom member 113 closes the opening 32 of the side member 25. The remainder of the bottom member 113 overlaps a part 114 of the side member 25. The bottom thickness of the battery of Comparative Example 3 indicates the thickness of the portion of the bottom member 113 that closes the opening 32 of the side member 25 and shows 0.12 mm.

[0034] In the battery of Comparative Example 4, the separator 7 of the aforementioned Battery 1 is replaced with another separator. The separator is such that the bottom member 113 of the separator 111 of the battery of the aforementioned Comparative Example 3 is replaced with another bottom member, and the other parts are the same as the separator 111 of the battery of the aforementioned Comparative Example 3. The replaced bottom member is formed from a base paper made of a polyethylene film with a thickness of 120 μm. A part of the bottom member closes the opening 32 of the side member 25. The remaining part of the bottom member overlaps a part 114 of the side member 25. The bottom thickness of the battery of Comparative Example 4 indicates the thickness of the part of the base paper made of the polyethylene film that closes the opening 32 of the side member 25, and shows 0.12 mm.

[0035] The separator 7 of the battery of Example 1 is produced based on the production of the separator in the aforementioned battery manufacturing method. The side member 25 of the separator 7 of the battery of Example 1 is formed from a tubular nonwoven fabric produced by double-winding a nonwoven fabric with a thickness of 120 μm made of vinylon, pulp, and vinylon binder fibers. The bottom member 26 of the separator 7 of the battery of Example 1 is formed from a hot melt resin. The separator 7 of the battery of Example 1 is further produced with the step of pressing the bottom member 26 toward the bottom surface portion 16 omitted. The bottom thickness of the battery of Example 1 indicates the thickness of the bottom member 26, and shows 1.2 mm.

[0036] The separator of the battery of Example 2 is produced based on the production of the separator in the aforementioned battery manufacturing method. The side member 25 of the separator 7 of the battery of Example 2 is formed from a tubular nonwoven fabric produced by double-winding a nonwoven fabric with a thickness of 120 μm made of vinylon, pulp, and vinylon binder fibers. The bottom member 26 of the separator 7 of the battery of Example 2 is formed from a hot melt resin. The separator 7 of the battery of Example 2 is further produced with the step of pressing the bottom member 26 toward the bottom surface portion 16 omitted. The bottom thickness of the battery of Example 2 indicates the thickness of the bottom member 26, and shows 1.0 mm.

[0037] The separator of the battery of Example 3 is manufactured based on the production of the separator in the battery manufacturing method described above. The side member 25 of the separator 7 of the battery of Example 3 is formed from a tubular non-woven fabric produced by double-winding a non-woven fabric made of vinylon, pulp, and vinylon binder fibers with a thickness of 120 μm. The bottom member 26 of the separator 7 of the battery of Example 3 is formed from a hot melt resin. The separator 7 of the battery of Example 3 is further manufactured by omitting the step of pressing the bottom member 26 toward the bottom surface portion 16. The bottom thickness of the battery of Example 3 indicates the thickness of the bottom member 26 and shows 0.3 mm.

[0038] The separator of the battery of Example 4 is manufactured based on the production of the separator in the battery manufacturing method described above. The side member 25 of the separator 7 of the battery of Example 4 is formed from a tubular non-woven fabric produced by double-winding a non-woven fabric made of vinylon, pulp, and vinylon binder fibers with a thickness of 120 μm. The bottom member 26 of the separator 7 of the battery of Example 4 is formed from a hot melt resin. The separator 7 of the battery of Example 4 is further manufactured by omitting the step of pressing the bottom member 26 toward the bottom surface portion 16. The bottom thickness of the battery of Example 4 indicates the thickness of the bottom member 26 and shows 0.1 mm.

[0039] The separator of the battery of Example 5 is manufactured based on the production of the separator in the battery manufacturing method described above. The side member 25 of the separator 7 of the battery of Example 5 is formed from a tubular non-woven fabric produced by double-winding a non-woven fabric made of vinylon, pulp, and vinylon binder fibers with a thickness of 120 μm. The bottom member 26 of the separator 7 of the battery of Example 5 is formed from a hot melt resin. The separator 7 of the battery of Example 5 is further manufactured by omitting the step of pressing the bottom member 26 toward the bottom surface portion 16. The bottom thickness of the battery of Example 5 indicates the thickness of the bottom member 26 and shows 0.05 mm.

[0040] The separator of the battery of Example 6 is manufactured based on the production of the separator of the battery manufacturing method described above. The side member 25 of the separator 7 of the battery of Example 6 is formed from a tubular non-woven fabric produced by double-winding a non-woven fabric made of vinylon, pulp, and vinylon binder fibers with a thickness of 120 μm. The bottom member 26 of the separator 7 of the battery of Example 6 is formed from a hot melt resin. The separator 7 of the battery of Example 6 is further manufactured by performing a step of pressing the bottom member 26 toward the bottom surface portion 16. The bottom thickness of the battery of Example 6 indicates the thickness of the bottom member 26 and is 0.1 mm.

[0041] The separator of the battery of Example 7 is manufactured based on the production of the separator of the battery manufacturing method described above. The side member 25 of the separator 7 of the battery of Example 7 is formed from a tubular non-woven fabric produced by double-winding a non-woven fabric made of vinylon, pulp, and vinylon binder fibers with a thickness of 120 μm. The bottom member 26 of the separator 7 of the battery of Example 7 is formed from polyethylene. The step of pressing the bottom member 26 toward the bottom surface portion 16 is omitted in the manufacture of the separator 7 of the battery of Example 7. The bottom thickness of the battery of Example 7 indicates the thickness of the bottom member 26 and is 0.3 mm.

[0042] The plurality of evaluation results include a plurality of negative electrode effective volumes, a plurality of first discharge test results, a plurality of second discharge test results, and a plurality of separator penetration evaluation results. The plurality of negative electrode effective volumes correspond to a plurality of battery samples. The negative electrode effective volume corresponding to a certain battery sample among the plurality of negative electrode effective volumes indicates the amount of the negative electrode 5 injected into the battery sample, and shows a value obtained by multiplying the value obtained by dividing the amount of the negative electrode 5 of the battery sample by the amount of the negative electrode 5 of the battery of Comparative Example 1 by 100.

[0043] The plurality of negative electrode effective volumes indicate that, for the batteries of Examples 1 to 7, the thinner the bottom thickness of the battery, the larger the negative electrode effective volume. The plurality of negative electrode effective volumes further indicate that the negative electrode effective volume of the battery of Example 6 is larger than the negative electrode effective volume of the battery of Example 4, showing that the negative electrode effective volume increases when the bottom member 26 is in close contact with the positive electrode can 11.

[0044] The plurality of first discharge test results correspond to a plurality of battery samples. The first discharge test result corresponding to a certain battery sample among the plurality of first discharge test results indicates the result derived by performing the first discharge test on that battery sample. In the first discharge test performed on a certain battery sample, a 5-minute discharge pattern is repeatedly executed every hour until the battery voltage of that battery sample becomes less than the cut-off voltage of 1.05 V, and the discharge time is derived. In the 5-minute discharge pattern, a 30-second discharge pattern is repeatedly executed 10 times. The 30-second discharge pattern is formed from a 2-second discharge period and a 28-second discharge period. In the 2-second discharge period, the battery sample is electrically connected to a load of 1500 mW, and the 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 battery sample is electrically connected to a load of 750 mW for 28 seconds, and the battery sample is pulse-discharged. During the period excluding the 5-minute discharge pattern within one hour, the battery sample is electrically insulated from the load so that the battery sample is not discharged.

[0045] The discharge time indicates the time during which the battery sample was discharged before the battery voltage of the battery sample became less than the cut-off voltage of 1.05 V. The first discharge test result corresponding to a certain battery sample among the plurality of first discharge test results indicates the value obtained by multiplying the average of the discharge times of 8 batteries fabricated as that battery sample by 100 and dividing the result by the average of the discharge times of 8 batteries fabricated as the battery of Comparative Example 1. The plurality of first discharge test results indicate that the battery sample with a larger first discharge test result has better discharge performance under heavy load.

[0046] The plurality of first discharge test results indicate that the first discharge test result of the battery of Comparative Example 2 is smaller than that of the battery of Comparative Example 1, indicating that the discharge performance of the battery of Comparative Example 2 under heavy load is worse than that of the battery of Comparative Example 1 under heavy load. The plurality of first discharge test results further indicate that the first discharge test result of the battery of Comparative Example 4 is smaller than that of the battery of Comparative Example 1, indicating that the discharge performance of the battery of Comparative Example 4 under heavy load is worse than that of the battery of Comparative Example 1 under heavy load. That is, the plurality of first discharge test results indicate that when the portion corresponding to the side member 25 of the separator contains a portion with poor ion conductivity, the discharge performance of the battery under heavy load deteriorates.

[0047] The plurality of first discharge test results further indicate that the first discharge test results of the batteries of Examples 1 to 7 are larger than those of the batteries of Comparative Examples 1, 2, and 4, indicating that the discharge performance of the batteries of Examples 1 to 7 under heavy load is better than that of the batteries of Comparative Examples 1, 2, and 4 under heavy load.

[0048] The plurality of first discharge test results further indicate that the first discharge test results of the batteries of Examples 3 to 7 are larger than those of the batteries of Examples 1 and 2, indicating that the discharge performance of the batteries of Examples 3 to 7 under heavy load is better than that of the batteries of Examples 1 and 2 under heavy load. That is, the plurality of first discharge test results indicate that the discharge performance of a battery with a bottom thickness of 0.3 mm or less under heavy load is better than that of a battery with a bottom thickness greater than 0.3 mm under heavy load.

[0049] The plurality of second discharge test results correspond to a plurality of battery samples. The second discharge test result corresponding to a certain battery sample among the plurality of second discharge test results indicates the result derived by performing the second discharge test on that battery sample. In the second discharge test performed on a certain battery sample, a discharge pattern of 8 hours is repeatedly executed until the battery voltage of that battery sample becomes less than the cut-off voltage of 1.0 V, and the discharge time is derived. The 8-hour discharge pattern is formed by a 1-hour discharge period and a 7-hour rest period. In the 1-hour discharge period, the battery sample is electrically connected to a 50 mA load. In the 7-hour 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 during which the battery sample was discharged before the battery voltage of that battery sample became less than the cut-off voltage of 1.0 V.

[0050] The first discharge test result corresponding to a certain battery sample among the plurality of second discharge test results indicates the value obtained by multiplying the average of the discharge times of 8 batteries fabricated as that battery sample by 100 and dividing it by the average of the discharge times of 8 batteries fabricated as the battery of Comparative Example 1. The plurality of second discharge test results indicate that the higher the second discharge test result of a battery sample, the better the discharge performance under medium and light loads.

[0051] The plurality of second discharge test results indicate that the second discharge test results of the batteries of Examples 2 to 7 are greater than the second discharge test results of the batteries of Example 1, and the discharge performance of the batteries of Examples 2 to 7 under heavy loads is better than the discharge performance of the batteries of Example 1 under heavy loads. That is, the plurality of second discharge test results indicate that the discharge performance of the batteries with a bottom thickness of 1.0 mm or less under heavy loads is better than the discharge performance of the batteries with a bottom thickness greater than 1.0 mm under heavy loads.

[0052] The plurality of second discharge test results further show that the second discharge test results of the batteries in Examples 3 to 7 are greater than those of the battery in Example 2, indicating that the discharge performance under heavy load of the batteries in Examples 3 to 7 is better than that of the battery in Example 2. That is, the plurality of second discharge test results indicate that the discharge performance under heavy load of a battery with a bottom thickness of 0.3 mm or less is better than that of a battery with a bottom thickness greater than 0.3 mm.

[0053] The plurality of negative electrode effective volumes and the plurality of second discharge test results indicate that the greater the negative electrode effective volume of a battery, the greater the second discharge test result. That is, it shows that the greater the negative electrode effective volume of a battery, the better the discharge performance under medium and light loads.

[0054] The plurality of separator penetration evaluation results correspond to the plurality of battery samples. The separator penetration evaluation result corresponding to a certain battery sample among the plurality of separator penetration evaluation results shows the result derived by performing a separator penetration evaluation test on that battery sample. In the separator penetration evaluation test performed on a certain battery sample, a 5-minute discharge is repeatedly performed every day until the battery voltage of that battery sample becomes smaller than a predetermined end voltage, and it is confirmed whether the dendrite growing from the negative electrode 5 penetrates the bottom member. In the 5-minute discharge, that battery sample is electrically connected to a 3.9 Ω load. During the rest time different from the 5-minute discharge in a day, that battery sample is electrically insulated from the load so that the battery sample is not discharged. The separator penetration evaluation result corresponding to a certain battery sample among the plurality of separator penetration evaluation results shows the number of batteries among the 10 batteries fabricated as that battery sample in which the dendrite penetrates the bottom member. The plurality of separator penetration evaluation results indicate that the greater the separator penetration evaluation result of a battery sample, the easier it is for the dendrite growing from the negative electrode 5 to penetrate the bottom member.

[0055] The results of the multiple separator penetration evaluations indicate that no dendrites penetrating the bottom member were formed in the batteries of Comparative Examples 1 and 4 and the batteries of Examples 1 to 7, while dendrites penetrating the bottom member were formed in the batteries of Comparative Examples 2 and 3. That is, the results of the multiple separator penetration evaluations show that in a battery in which a hot melt resin or polyethylene is used for the bottom member, dendrites growing from the negative electrode 5 are less likely to penetrate the bottom member compared to a battery in which the bottom member is formed only of a nonwoven fabric. The results of the multiple separator penetration evaluations further show that in the batteries of Examples 1 to 7, dendrites growing from the negative electrode 5 are less likely to penetrate the bottom member compared to the batteries of Comparative Examples 1 to 4.

[0056] [Effect of Battery 1 of the Embodiment] Battery 1 of the embodiment includes a positive electrode can 11, a positive electrode 3 formed in a tubular shape and disposed inside the positive electrode can 11, a negative electrode 5 disposed inside the positive electrode 3, and a separator 7. The separator 7 includes a side member 25 formed of a nonwoven fabric and a bottom member 26 formed of a hot melt resin through which ions hardly permeate compared to the nonwoven fabric. The side member 25 is sandwiched between the negative electrode 5 and the positive electrode 3. The bottom member 26 is sandwiched between the negative electrode 5 and the positive electrode can 11. The bottom member 26 is joined to the side member 25 so that the nonwoven fabric is not sandwiched between the negative electrode 5 and the positive electrode can 11, and the hot melt resin is not sandwiched between the negative electrode 5 and the positive electrode 3.

[0057] In Battery 1, since the nonwoven fabric of the side member 25 is not sandwiched between the negative electrode 5 and the positive electrode can 11, the bottom member 26 can be made thin. Since the bottom member 26 of Battery 1 is thin, the capacity of the negative electrode 5 can be increased, and the discharge performance under medium and light loads can be improved. In Battery 1, since the hot melt resin of the bottom member 26 is not sandwiched between the negative electrode 5 and the positive electrode 3, the area of the portion where ions hardly permeate in the region between the negative electrode 5 and the positive electrode 3 can be reduced. Since the area of the portion where ions hardly permeate between the negative electrode 5 and the positive electrode 3 of Battery 1 is reduced, the ion conduction between the negative electrode 5 and the positive electrode 3 can be improved, and the discharge performance under heavy loads can be improved.

[0058] Also, the bottom member 26 of the battery 1 of the embodiment is in close contact with the positive electrode can 11. Due to the bottom member 26 of the battery 1 being in close contact with the positive electrode can 11, the capacity of the negative electrode 5 can be increased, and the discharge performance under medium and light loads can be improved.

[0059] Also, the thickness of the bottom member 26 of the battery 1 of the embodiment is 0.1 mm or more and 1 mm or less. Due to the thickness of the bottom member 26 of the battery 1 being 1 mm or less, the capacity of the negative electrode 5 can be increased, and the discharge performance under medium and light loads can be improved. Due to the thickness of the bottom member 26 of the battery 1 being 0.1 mm or more, even when the bottom member 26 bends while being in close contact with the positive electrode can 11, the bottom member 26 can be prevented from being damaged. Further, due to the thickness of the bottom member 26 of the battery 1 being 0.3 mm or less, the capacity of the negative electrode 5 can be further increased, and the discharge performance under medium and light loads can be further improved.

[0060] Also, the bottom member 26 of the battery 1 of the embodiment is formed of a hot-melt resin that becomes liquid when heated. In this case, for the battery 1, by bringing one end of the side member 25 into contact with the hot-melt resin in a liquid state, the bottom member 26 joined to the side member 25 can be easily produced, and the manufacturing can be facilitated.

[0061] The battery manufacturing method of the embodiment includes manufacturing the side member 25, after the side member 25 is manufactured, manufacturing the bottom member 26 joined to the side member 25, manufacturing the separator 7, and after the separator 7 is manufactured, inserting the separator 7 inside the positive electrode 3. According to such a battery manufacturing method, the separator 7 can be appropriately and easily manufactured so that the non-woven fabric is not sandwiched between the negative electrode 5 and the positive electrode can 11, and the hot-melt resin is not sandwiched between the negative electrode 5 and the positive electrode 3.

[0062] In addition, in the battery manufacturing method of the embodiment, the bottom member 26 is produced by bringing one end of the side member 25 into contact with a liquid hot melt resin. Such a battery manufacturing method can appropriately and easily form the bottom member 26, can appropriately and easily produce the separator 7, and can appropriately and easily produce the battery 1.

[0063] Further, the battery manufacturing method of the embodiment further includes pressurizing the bottom member 26 toward the positive electrode can 11 after the separator 7 is inserted inside the positive electrode 3, and filling the inside of the separator 7 with the negative electrode 5 after the bottom member 26 is pressurized. Such a battery manufacturing method can appropriately adhere the bottom member 26 of the separator 7 to the positive electrode can 11 even when the positive electrode can 11 has irregularities formed thereon.

[0064] [Battery of Modification Example] As shown in FIG. 9, in the battery of the modification example, the separator 7 of the above-described battery 1 is replaced with another separator 41, and the other parts are the same as those of the above-described battery 1. FIG. 9 is a perspective view showing the separator 41 of the battery of the modification example. The separator 41 includes a side member 42 and a bottom member 26. That is, the side member 25 of the above-described separator 7 is replaced with the side member 42, and the other parts are the same as those of the above-described separator 7. The side member 42 is formed of a non-woven fabric formed of an insulator exemplified by vinylon, pulp, or the like, similarly to the above-described side member 25.

[0065] The side member 42 includes a main body portion 43 and a tip portion 44. The main body portion 43 is formed along the side surface of a cylinder. The tip portion 44 is formed along the side surface of a frustum of a cone. The tip portion 44 is connected to the main body portion 43 such that the end corresponding to the larger bottom surface of the frustum of the cone in the tip portion 44 faces one end of the main body portion 43. The bottom member 26 is joined to the tip portion 44 so as to close the end corresponding to the smaller bottom surface of the frustum of the cone in the tip portion 44. That is, the separator 41 is formed to taper toward the tip where the bottom member 26 is formed.

[0066] The battery of the modified example is manufactured based on the battery manufacturing method of the above-described embodiment, similarly to the above-described battery 1. Since the non-woven fabric of the side member 42 is not sandwiched between the negative electrode 5 and the positive electrode can 11 in the battery of the modified example, the bottom member 26 can be made thinner, the capacity of the negative electrode 5 can be increased, and the discharge performance under medium and light loads can be improved, similarly to the above-described battery 1. Since the hot melt resin of the bottom member 26 is not sandwiched between the negative electrode 5 and the positive electrode 3 in the battery of the modified example, the area of the portion where ions hardly permeate in the region between the negative electrode 5 and the positive electrode 3 can be reduced, and the discharge performance under heavy loads can be improved, similarly to the above-described battery 1.

[0067] The separator 41 of the battery of the modified example has the end on the side closer to the bottom member 26 of the side member 42 formed to be tapered, and is more easily inserted into the positive electrode 3 as compared with the separator 7 of the above-described battery 1. For this reason, the battery of the modified example can facilitate the operation of inserting the separator 41 into the positive electrode 3. Further, since the end on the side closer to the bottom member 26 of the side member 42 is formed to be tapered in the battery of the modified example, the size of the bottom member 26 can be reduced, and the amount of the material used for the bottom member 26 can be reduced.

[0068] Although the embodiments have been described above, the embodiments are not limited by the above-described content. Further, the above-described components include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those 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 changes of the components can be made without departing from the gist of the embodiments.

Explanation of Reference Numerals

[0069] 1: Battery 3: Positive electrode 5: Negative electrode 7: Separator 11: Positive electrode can 25: Side member 26: Bottom member

Claims

1. A positive electrode can, a positive electrode formed in a tubular shape and disposed inside the positive electrode can, a negative electrode disposed inside the positive electrode, and a separator, wherein the separator has a side member formed of a first material, and a bottom member formed of an insulating hot melt resin that becomes liquid when heated, the side member is sandwiched between the negative electrode and the positive electrode, the bottom member is sandwiched between the negative electrode and a bottom surface portion of the positive electrode can that is not in contact with the positive electrode, the bottom member is joined to the side member so that the first material is not sandwiched between the negative electrode and the bottom surface portion, and the hot melt resin is not sandwiched between the negative electrode and the positive electrode, and an end of the side member close to the bottom member is formed to become thinner as it approaches the end battery.

2. The bottom member is in close contact with the bottom surface portion The battery according to claim 1.

3. The thickness of the bottom member is 0.1 mm or more and 1 mm or less The battery according to claim 1 or claim 2.

4. The thickness of the bottom member is 0.1 mm or more and 0.3 mm or less The battery according to claim 3.

5. A positive electrode can, a positive electrode formed in a tubular shape and disposed inside the positive electrode can, a negative electrode disposed inside the positive electrode, and a separator, wherein the separator has a side member formed of a first material, and a bottom member formed of a second material through which ions hardly permeate compared to the first material, the side member is sandwiched between the negative electrode and the positive electrode, the bottom member is sandwiched between the negative electrode and the positive electrode can battery is a battery manufacturing method for manufacturing the same, manufacturing the side member, after the side member is manufactured, manufacturing the bottom member and thus the separator by bringing one end of the side member into contact with a liquid hot melt resin, and after the separator is manufactured, inserting the separator inside the positive electrode and a battery manufacturing method comprising the above.

6. A positive electrode can, a positive electrode formed in a tubular shape and disposed inside the positive electrode can, a negative electrode disposed inside the positive electrode, and a separator, wherein the separator has a side member formed of a first material, and a bottom member formed of a second material through which ions hardly permeate compared to the first material, the side member is sandwiched between the negative electrode and the positive electrode, the bottom member is sandwiched between the negative electrode and the positive electrode can Battery A battery manufacturing method for manufacturing a battery, manufacturing the side member, after the side member is manufactured, manufacturing the bottom member joined to the side member to manufacture the separator, after the separator is manufactured, inserting the separator inside the positive electrode, after the separator is inserted inside the positive electrode, pressing the bottom member toward the positive electrode can, after the bottom member is pressed, filling the inside of the separator with the negative electrode and a battery manufacturing method comprising the steps thereof.

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