JP2014022073A - Manufacturing method and apparatus for square secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a manufacturing method for a square secondary battery which can reduce the manufacturing cost by injecting an electrolyte efficiently into a battery can in the liquid injection process.SOLUTION: A square secondary battery 1 includes a flat electrode group 4, a square battery can 2 for housing an electrode group 4 in such a position that a pair of flat surfaces of the electrode group 4 extend vertically, a battery lid 3 closing the upper part of the battery can 2, and a liquid injection port 7 provided to open in the battery lid 3 and injecting an electrolyte into the battery can 2. The manufacturing method for a square secondary battery includes a liquid injection step for injecting a liquid into the battery can 2, by inserting a liquid injection nozzle 221 into the battery can 2 from the liquid injection port 7, and discharging the electrolyte from the liquid injection nozzle 221 between the electrode group 4 and the battery lid 3, toward one side in the lateral width direction of the electrode group 4.

Description

  The present invention relates to a method and apparatus for manufacturing a rectangular secondary battery used for, for example, in-vehicle use.

  In recent years, lithium ion secondary batteries with high energy density have been developed as power sources for electric vehicles and the like. Some lithium ion secondary batteries have various shapes, and among them, the square secondary battery has high volumetric efficiency and is adopted for in-vehicle use.

  In order to realize a high-performance secondary battery, there is a tendency to reduce the useless space in the battery can and increase the volume occupied by the electrode group. In such a situation, time is required for the injection step of injecting the electrolytic solution into the battery can, so that an increase in the manufacturing cost of the battery and deterioration of the battery characteristics become problems.

  For example, Patent Document 1 discloses a battery manufacturing method in which an electrode group is housed in a battery can and then an electrolytic solution is injected. According to this method, in a state where the battery can containing the electrode group and the electrolytic solution are heated, the cycle of the normal pressure state and the reduced pressure state is repeated at least twice, and the electrolytic solution is divided and injected. Can be made more efficient.

JP 2004-241222 A

  However, the technique disclosed in Patent Document 1 does not consider the method of injecting the electrolyte into the battery can. The electrolyte injected into the battery can from the injection port provided on the sealing plate flows into the bottom of the can through the edge of the electrode group having a relatively wide gap. When the electrolyte is injected vertically toward the electrode group, the electrolyte branches and flows in the width direction of the electrode group on the upper surface of the electrode group, and flows from both ends of the upper surface of the electrode group toward the bottom of the can. To do. In this case, since the inflowing electrolyte covers the air exhaust path in the battery can and inhibits the replacement of the electrolyte and air in the battery can, air remains in a space at a certain height from the bottom of the can. The air at the bottom of the can is replaced with the electrolyte over time, but the replacement hardly progresses within the processing time for mass production, for example within a few minutes, and the time required for pouring the electrolyte into the battery can become longer.

  In addition, in order to promote the penetration of the injected electrolyte into the electrode group, the inside of the battery can may be decompressed following the injection of the electrolyte, but a large amount of air remains at the bottom of the can. If this is the case, the risk that the air expands and the electrolyte is pushed up and adheres to the liquid injection hole increases. If electrolyte adheres to the vicinity of the liquid injection hole, when the liquid injection hole is attached to the liquid injection hole and sealed by laser welding after the completion of liquid injection, welding failure is caused between the liquid injection hole and the liquid injection plug due to the heat of welding. May cause. Therefore, in order to reduce the risk of poor welding, it is necessary to divide the injection into multiple times and set the injection volume to be small, which increases the time for the injection process and increases the manufacturing cost of the battery. To do.

  An object of the present invention is to provide a method and an apparatus for manufacturing a rectangular secondary battery that is efficient in injecting an electrolytic solution into a battery can and is inexpensive to manufacture.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present invention includes a plurality of means for solving the above-described problems. To give an example, the electrode is in a posture in which a flat electrode group and a pair of flat surfaces of the electrode group extend vertically. A rectangular battery can that accommodates a group; a battery lid that closes an upper portion of the battery can; an injection port that is provided in the battery lid so as to inject an electrolyte into the battery can; A method of manufacturing a prismatic secondary battery comprising: a liquid injection nozzle inserted into the battery can from the liquid injection port, and the electrode between the electrode group and the battery lid from the liquid injection nozzle. It includes a liquid injection step of discharging the electrolytic solution toward one side in the lateral width direction of the group and injecting it into the battery can.

  According to the present invention, when the electrolytic solution is injected into the battery can, the air in the battery can and the electrolytic solution can be efficiently replaced, so that the time of the injection process can be shortened. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is an external perspective view of a prismatic secondary battery according to an embodiment. The disassembled perspective view of the square secondary battery shown in FIG. The flowchart explaining the manufacturing method of the square secondary battery concerning embodiment. The conceptual diagram of the liquid injection apparatus of the square secondary battery concerning embodiment. Sectional drawing which shows the state which inserted the liquid injection nozzle in embodiment into the liquid injection port. Sectional drawing which shows the state which inserted the other injection nozzle in embodiment into the injection hole. Sectional drawing which shows the state which inserted the other injection nozzle in embodiment into the injection hole. The top view which expands and shows the injection hole vicinity of a battery cover. Sectional conceptual diagram explaining the flow of the electrolyte solution injected into the battery can. Sectional drawing which shows the state which sealed the liquid injection port with the sealing stopper.

  Next, embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an external perspective view of the prismatic secondary battery according to the present embodiment, and FIG. 2 is an exploded perspective view of the prismatic secondary battery shown in FIG.

  The prismatic secondary battery 1 is an in-vehicle lithium ion secondary battery used for electric vehicles, hybrid vehicles, plug-in hybrid vehicles, and the like. As shown in FIGS. 1 and 2, the rectangular secondary battery 1 includes a battery can 2 and a battery lid 3. The battery can 2 is bent at a rectangular bottom wall surface PB, a pair of wide side wall surfaces PW that are bent at two long side portions of the bottom wall surface PB, and two short side portions of the bottom wall surface PB. It has a square shape having a pair of narrow side wall surfaces PN facing each other, and a rectangular opening 2a opened upward is formed at the top.

  The battery can 2 accommodates an electrode group (rolled body) 4 to be described later. The opening 2 a of the battery can 2 is sealed by the battery lid 3. The battery lid 3 has a rectangular flat plate shape that closes the opening 2a of the battery can 2 between the upper ends of the pair of wide side wall surfaces PW and between the upper ends of the pair of narrow side wall surfaces PN. The battery can 2 and the battery lid 3 are both made of an aluminum alloy and are liquid-tightly welded by laser welding to constitute a rectangular parallelepiped sealed container.

  The battery lid 3 is provided with a positive electrode terminal 5A and a negative electrode terminal 5B via an insulating member. The positive electrode terminal 5 </ b> A and the negative electrode terminal 5 </ b> B are disposed separately on one side and the other side in the long side direction of the battery lid 3. Electric power is supplied from the electrode group 4 to the external load via the positive electrode terminal 5A and the negative electrode terminal 5B, and the electric power generated outside is charged in the electrode group 4.

  In addition to the positive electrode terminal 5A and the negative electrode terminal 5B, the battery cover 3 is provided with a gas discharge valve 6 and a liquid injection port 7. The gas discharge valve 6 is disposed at the central position in the long side direction of the battery lid 3, and the liquid injection port 7 is disposed at a position between the gas discharge valve 6 and the negative electrode terminal 5 </ b> B. The gas discharge valve 6 is opened when the pressure in the battery can 2 rises above a predetermined value, and discharges the gas in the battery can 2 to reduce the pressure in the battery can 2. It has the structure which ensures the property.

  The liquid injection port 7 is used to inject an electrolyte into the battery can 2 after the opening 2 a of the battery can 2 is sealed with the battery lid 3. The electrolytic solution is injected using an injection device 200 (see FIG. 4). The liquid injection port 7 is sealed with a sealing plug 8 after the electrolytic solution is injected into the battery can 2. The liquid injection port 7 is provided at a position displaced toward the negative electrode terminal 5B side from the central position in the long side direction of the battery lid 3.

  As shown in FIG. 2, the electrode group 4 is accommodated in the battery can 2 of the prismatic secondary battery 1 through an insulating sheet 9. The electrode group 4 is configured by winding a positive electrode and a negative electrode with a separator interposed therebetween. The electrode group 4 has a flat shape having a pair of flat surfaces and a pair of curved surfaces, and a pair of side end portions are formed on both sides in the winding axis direction.

  The electrode group 4 is housed in the battery can 2 in a posture state in which the winding axis direction is lateral and the pair of flat surfaces extend vertically, and the electrode group 4 is placed on each wide side wall surface PW of the battery can 2. Each flat surface is opposed to each other, and each side end portion of the electrode group 4 is opposed to each narrow side wall surface PN of the battery can 2. The lower curved surface faces the bottom wall surface PB of the battery can 2, and the upper curved surface is disposed in the opening 2 a of the battery can 2.

  The flat thickness of the electrode group 4 is such that the wide surface of the electrode group 4 and the wide side wall surface PW of the battery can 2 are in contact with each other through an insulating sheet 9 so that the electrode group 4 is pressed into the battery can 2 by a predetermined amount. It is set to a dimension that can be inserted by pressing with pressure. The length of the electrode group 4 in the winding axis direction is predetermined between the pair of side end portions on both sides in the lateral width direction of the electrode group 4 and the narrow side wall surface PN of the battery can 2 while being accommodated in the battery can 2. The dimension is set such that the gap is formed. 4 A of positive electrode metal foil exposed parts are formed in the side edge part of the winding group direction one side of the electrode group 4, and a negative electrode is formed in the side edge part of the electrode group 4 on the other side of the winding axis direction. A negative electrode connection portion 4B made of a metal foil exposed portion is formed.

  The positive electrode connection portion 4A is connected to the positive electrode terminal 5A via the positive electrode current collector plate 11A, and the negative electrode connection portion 4B is connected to the negative electrode terminal 5B via the negative electrode current collector plate 11B. One end of the positive electrode current collector plate 11A is connected to the positive electrode terminal 5A, extends from the positive electrode terminal 5A toward the can bottom (bottom wall surface PB) of the battery can 2, and the other end is connected to the positive electrode connection portion 4A. One end of the negative electrode current collector plate 11B is connected to the negative electrode terminal 5B, extends from the negative electrode terminal 5B toward the can bottom (bottom wall surface PB) of the battery can 2, and the other end is connected to the negative electrode connection portion 4B.

  The positive terminal 5A and the positive current collector 11A are made of an aluminum alloy, and the negative terminal 5B and the negative current collector 11B are made of a copper alloy. Insulating seal members (gaskets) 12A and 12B and insulating members 13A and 13B are interposed between the positive electrode terminal 5A and the positive electrode current collector plate 11A, and the negative electrode terminal 5B and the negative electrode current collector plate 11B, respectively, with the battery lid 3. It is electrically insulated from the battery lid 3. The battery lid 3 is formed with through holes 3a and 3b that engage with the insulating sealing members (gaskets) 12A and 12B.

  In the present embodiment, the case where the electrode group 4 is a wound body has been described as an example. However, the present invention is not limited to this. For example, a plurality of rectangular positive electrodes and negative electrodes are interposed between the separators. A laminated body laminated via the electrode may be used as the electrode group 4.

FIG. 3 is a flowchart showing the procedure of the manufacturing process of the prismatic secondary battery in the present embodiment.
First, the electrode group 4 is produced (step S1). The electrode group 4 is produced by winding a positive electrode and a negative electrode in a flat shape with a separator interposed therebetween. In the electrode group 4, the positive electrode collector plate 11A and the negative electrode collector plate 11B are connected to the positive electrode connector 4A and the negative electrode connector 4B by ultrasonic welding, respectively. Each of the positive electrode current collector plate 11A and the negative electrode current collector plate 11B is attached in advance to the battery lid 3, and constitutes a lid assembly. The power generation element assembly is configured by connecting and supporting the positive electrode connection portion 4A and the negative electrode connection portion 4B of the electrode group 4 to the positive electrode current collector plate 11A and the negative electrode current collector plate 11B of the lid assembly.

  Next, the electrode group 4 portion of the power generation element assembly is inserted into the battery can 2 (step S2). The electrode group 4 is inserted into the battery can 2 with its periphery covered with an insulating sheet 9 (see FIG. 2). The electrode group 4 is inserted into the battery can 2 by contacting with the insulating sheet 9 between the wide surface of the electrode group 4 and the wide side wall surface PW of the battery can 2 and pressing it with a predetermined pressing force. . In the electrode group 4, a predetermined gap is formed between the pair of side end portions on both sides in the widthwise direction of the electrode group 4 and the narrow side wall surface PN of the battery can 2 while being accommodated in the battery can 2. .

  The insulating sheet 9 covers the electrode group 4 together with the positive electrode current collector plate 11 </ b> A and the negative electrode current collector plate 11 </ b> B, and insulates the electrode group 4 from the battery can 2. By inserting the electrode group 4 into the battery can 2, the opening 2 a of the battery can 2 is closed by the battery lid 3. In this state, the battery lid 3 is laser welded to the battery can 2 to seal the opening 2a (step S3). Through the above steps, the battery member 1A (see FIG. 4) before the electrolyte solution is injected is formed.

  Next, the battery member 1A is conveyed into the liquid injection device 200 (see FIG. 4), and the electrolytic solution is injected into the battery can 2 from the liquid injection port 7 of the battery lid 3 (step S4). Here, a liquid injection nozzle 221 is inserted into the battery can 2 from the liquid injection port 7, and from the liquid injection nozzle 221 between the electrode group 4 and the battery lid 3 and toward one side in the lateral width direction of the electrode group 4. The electrolytic solution is discharged and injected into the battery can 2.

  And after pouring a predetermined amount of electrolyte solution in the battery can 2, the sealing stopper 8 is attached to the injection port 7, and laser welding is carried out, and the injection port 7 is sealed liquid-tightly (step S5). After sealing, the sample is allowed to stand for a certain period of time, and the positive electrode plate, the negative electrode plate, and the separator in the electrode group 4 are sufficiently impregnated with the electrolyte (step S6). Thereafter, the battery is charged / discharged through the positive electrode terminal 5A and the negative electrode terminal 5B, and left standing (aging) in an appropriate charged state and temperature environment (step S7), thereby completing the rectangular secondary battery 1 (see FIG. 1). To do.

FIG. 4 is a conceptual diagram illustrating the overall configuration of the liquid injection device in the present embodiment.
The liquid injection device 200 includes an electrolytic solution tank 201 that stores an electrolytic solution, a liquid injection passage 202 connected to the electrolytic solution tank 201, a sealed container 210 that houses the battery member 1A, and an exhaust that exhausts air in the container. A passage 204, a liquid injection valve 203 for opening and closing the liquid injection passage 202, an exhaust valve 205 for opening and closing the exhaust passage 204, and a liquid injection nozzle 221 inserted into the liquid injection port 7 of the battery member 1A are provided.

  The sealed container 210 has a structure that can be divided vertically, and is a space that is sealed between the case 212 that holds the battery member 1 </ b> A in an upright posture and the case 212 by closing the upper portion of the case 212. A case lid 211 is formed. A liquid injection passage 202 and an exhaust passage 204 are fixed to the case lid 211 and communicate with each other in the sealed container 210.

  The liquid injection nozzle 221 is provided integrally with the case lid 211, and a base end thereof is connected to and connected to the liquid injection passage 202. The liquid injection nozzle 221 protrudes downward from the case lid 211 and is arranged at a position facing the through hole 21 of the liquid injection port 7 above the battery member 1A. The top of the case 212 is closed with the case lid 211 so that the tip of the liquid injection nozzle 221 is inserted into the through hole 21 of the liquid injection port 7. The liquid injection nozzle 221 is inserted into the battery can 2 from the liquid injection port 7 and faces the narrow side wall surface PN on the negative electrode side between the electrode group 4 and the battery lid 3 and on one side in the horizontal width direction of the electrode group. A structure for discharging the electrolytic solution.

The details of the liquid injection process in step S4 will be described with reference to FIG.
First, when the battery member 1A is conveyed and supplied into the liquid injection device 200 and is held in a preset holding position, the case lid 211 of the sealed container 210 is lowered and the battery member 1A is moved to the sealed container. The liquid injection nozzle 221 is inserted into the through hole 21 of the liquid injection port 7 of the battery lid 3 at the same time. Next, the liquid injection valve 203 is opened, the electrolytic solution is allowed to flow from the electrolytic solution tank 201 into the liquid injection passage 202, and the electrolytic solution is injected from the liquid injection passage 202 into the battery can 2. The air in the battery can 2 is exhausted to the outside of the battery can 2 from the gap between the through hole 21 of the liquid injection port 7 and the liquid injection nozzle 221 according to the amount of the electrolyte injected into the battery can 2. Is done.

  A decompression device (not shown), a pressurization device, and an air release valve (not shown) are arranged at the tip of the exhaust passage 204, and any one of them can be selected and switched by a switching valve (not shown). . In order to perform liquid injection efficiently in a short time, the liquid injection operation is divided into a plurality of times by opening and closing the liquid injection valve 203, and the exhaust valve 205 is opened and closed between the liquid injection operations. At that time, by appropriately adjusting the air pressure in the battery can 2 using the decompression device, the pressurization device, and the air release valve, the replacement of the air in the gap inside the electrode group 4 and the electrolytic solution can be promoted. . After injecting a predetermined amount of electrolytic solution, the injection nozzle 221 is retracted from the injection port 7, the sealing plug 8 is attached to the injection port 7 and laser welding is performed, and the injection port 7 is sealed in a liquid-tight manner. To do.

5A to 5C are cross-sectional views showing a state in which the liquid injection nozzle is inserted into the through hole of the liquid injection port.
The liquid injection nozzle 221 has a discharge part 223 that opens toward one narrow side wall surface PN of the pair of narrow side wall surfaces PN of the battery can 2. Then, an insertion part 222 that is inserted into the through hole 21 of the liquid injection port 7 and through which the electrolyte flows, and a direction change for converting the flow of the electrolyte that has passed through the insertion part 222 toward the discharge part 223. Part 224. The liquid injection nozzle 221 can convert the flow direction of the electrolytic solution from the direction orthogonal to the winding axis direction of the electrode group 4 so as to be substantially parallel to the winding axis direction by the direction conversion unit 224. The discharge part 223 opens toward the narrow side wall surface PN on the negative electrode side, which is the narrow side wall surface PN closer to the liquid injection port 7.

  The liquid injection nozzle 221 shown in FIG. 5A includes an insertion part 222 having a cylindrical shape smaller in diameter than the through hole 21 of the liquid injection port 7, a direction changing part 224a provided at the tip of the insertion part 222, and a negative electrode connection part. And a discharge part 223 that opens toward the direction and discharges the electrolytic solution whose direction is changed by the direction change part 224a. The direction changing portion 224a has an inclined surface that is inclined with respect to the axial direction of the insertion portion 222. The inclined surface is inclined so as to gradually move toward the discharge portion 223 as it moves from the upper side to the lower side of the battery can 2. With this inclined surface, the flow direction of the electrolyte can be changed to a direction orthogonal to the axial direction of the insertion portion 222 and substantially parallel to the winding axis direction of the electrode group 4. As shown by a thick arrow in the drawing, the electrolytic solution passes through the insertion portion 222 of the liquid injection nozzle 221 and is discharged from the discharge portion 223 toward the narrow side wall surface PN on the negative electrode side of the battery can 2.

  The direction changing part 224b of the liquid injection nozzle 221 shown in FIG. 5B has an orthogonal surface orthogonal to the axial direction of the insertion part 222, and the flow direction of the electrolyte is changed by the orthogonal surface to the axial direction of the insertion part 222. Can be converted to a direction that is orthogonal to the direction of the winding axis and substantially parallel to the winding axis direction of the electrode group 4. Similarly to the configuration shown in FIG. 5A, the electrolytic solution is discharged from the discharge portion 223 toward the narrow side wall surface PN on the negative electrode side of the battery can 2.

  In the case of the liquid injection nozzle 221 shown in FIGS. 5A and 5B, the protruding portion 223 does not protrude outward in the radial direction from the outer diameter of the insertion portion 222, so the size of the through hole 21 of the liquid injection port 7 is set to the insertion portion 222. It is possible to make the size slightly larger than the outer diameter. Therefore, the through hole 21 can be prevented from becoming large, the battery lid 3 can be maintained with high rigidity, and the battery lid 3 can be easily manufactured. Further, by reducing the size of the through hole 21, the sealing plug 8 can be reduced in size, and the welding area of the sealing plug 8 can be reduced accordingly, thereby reducing the risk of welding failure.

  The shape of the direction changing part 224 of the liquid injection nozzle 221 is not particularly limited as long as the above purpose is achieved. For example, like the direction changing part 224c shown in FIG. 5C, the shape changes from the upper side to the lower side of the battery can 2. Accordingly, it may be a concave curved surface that gradually transitions in the direction of the discharge portion, and the discharge portion 223 of the liquid injection nozzle 221 has a configuration that protrudes with respect to the outer shape of the liquid injection nozzle 221 in the diameter direction. May be.

  The electrolyte flows in the insertion portion 222 of the injection nozzle 221 in the substantially vertical direction toward the electrode group 4, and then the narrow side wall surface PN on the negative electrode connection portion side by the direction changing portion 224 (224a, 224b, 224c). The direction of flowing approximately 90 ° toward the discharge part 223 that opens toward the direction (left side in FIGS. 5A to 5C) is converted and discharged from the discharge part 223 into the battery can 2, and the inside of the battery can 2 passes through the negative electrode side Flows in a direction substantially parallel to the winding axis direction toward the narrow side wall surface PN.

  In the case of the liquid injection nozzle 221 shown in FIG. 5C, since the discharge part 223 protrudes radially outside the insertion part 222, the electrolyte discharged from the discharge part 223 is difficult to scatter and the discharge direction is accurately controlled. Can do. In particular, since the direction changing portion 224c converts the flow of the electrolyte solution by the concave curved surface, it is easy to attach the direction of the flow and can be discharged straight in a predetermined direction. However, since the opening 223 protrudes in the diameter direction of the liquid injection nozzle 221, it is necessary to increase the diameter of the through hole 21 of the liquid injection port 7 as the protrusion length increases. If the diameter of the through hole 21 of the liquid injection port 7 is made too large, the rigidity of the battery lid 3 becomes weak and easily deformed, which is not preferable. Therefore, it is desirable that the opening of the liquid injection nozzle 221 has a structure that does not protrude as much as possible with respect to the outer shape of the liquid injection nozzle 221 in the diameter direction.

FIG. 6 is an enlarged plan view showing the vicinity of the liquid injection port of the battery lid.
For example, as shown in FIG. 5 and FIG. 6, the liquid injection port 7 is opened to the concave portion 22 having a substantially circular shape in a plan view and provided in the concave bottom surface 23 of the concave portion 22. It has a through-hole 21 that penetrates. The through hole 21 has a round hole shape and is formed at the center position of the recess 22. As shown in FIGS. 5A to 5C, the through hole 21 has a diameter d 1, and the recess 22 has a larger diameter d 2 than the through hole 21. A concave bottom surface 23 is disposed around the upper end of the through hole 21 over the entire circumference. The liquid injection port 7 can be integrally formed when the battery lid 3 is press-molded, for example.

  FIG. 7 is a conceptual cross-sectional view illustrating the flow of the electrolyte solution injected into the battery can by the injection method of the present embodiment.

  In the liquid injection device 200, when the liquid injection nozzle 221 is inserted into the through hole 21, the electrolytic solution is discharged from the tip of the liquid injection nozzle 221 to inject the electrolytic solution into the battery can 2.

  The tip of the liquid injection nozzle 221 opens toward the narrow side wall surface PN on the negative electrode side so that the electrolyte is discharged substantially parallel to the winding axis direction of the electrode group 4. As shown by an arrow in FIG. 7, the electrolyte discharged from the liquid injection nozzle 221 travels through the upper space formed between the battery lid 3 and the electrode group 4 in the battery can 2 and has a width on the negative electrode side. It flows toward the narrow side wall surface PN. Then, it flows between one end of the electrode group 4 in the winding axis direction and the narrow side wall surface PN of the battery can 2, flows downward toward the bottom wall surface PB of the battery can 2, and reaches the bottom wall surface PB. It flows toward the positive electrode connecting portion along the bottom wall surface PB.

  When the lower space formed between the bottom wall surface PB and the electrode group 4 is filled with the electrolytic solution, the electrolytic solution is contained in the battery can 2 in the direction of the winding axis of the electrode group 4 and the positive electrode connecting portion. It flows toward the upper side of the battery can 2 between the narrow side wall surface PN on the side.

  Thus, in the liquid injection process of step S4, the electrolytic solution is discharged toward the narrow side wall surface PN on the negative electrode side that is closer to the liquid injection port 7. Accordingly, the electrolytic solution is quickly transferred from the upper space between the electrode group 4 and the battery lid 3 to the gap between the side end portion on the negative electrode side of the electrode group 4 and the narrow side wall surface PN on the negative electrode side of the battery can 2. It can be poured and can reach the bottom of the battery can 2 in a short time. Then, the air at the bottom of the battery can 2 is passed through the gap between the side end portion on the positive electrode side of the electrode group 4 and the narrow side wall portion PN on the positive electrode side of the battery can 2, so that the electrode group 4 and the battery It is possible to reach the upper space between the lid 3. The air in the battery can 2 is exhausted to the outside of the battery can 2 through a gap between the through hole 21 of the liquid injection port 7 and the liquid injection nozzle 221 as indicated by broken line arrows in FIGS. 5A to 5C. Therefore, efficient replacement of the air and the electrolyte in the battery can 2 is possible, and the time of the liquid injection process can be shortened.

  Due to the flow of the electrolyte solution, the air in the battery can 2 is discharged out of the battery can 2 from the liquid injection port 7 without remaining in the lower space formed between the bottom wall surface PB of the battery can 2 and the electrode group 4. Is done. As the injection amount of the electrolytic solution increases, the liquid level of the electrolytic solution rises in the battery can 2, mainly from the positive electrode connecting portion and the negative electrode connecting portion at both ends in the winding group direction of the electrode group 4 to the inside of the electrode group 4. Electrolyte penetrates.

  In the present embodiment, the electrolytic solution can be injected without retaining air in the lower space formed between the bottom wall surface PB of the battery can 2 and the electrode group 4. Can be efficiently replaced. Further, when the inside of the liquid injection device 200 is depressurized in order to promote the penetration of the electrolytic solution into the electrode group 4 after the electrolytic solution has been injected, there is no rise in the liquid level of the electrolytic solution due to the expansion of air in the space. In addition, the electrolytic solution does not adhere to the welded portion in the vicinity of the injection port 7.

FIG. 8 is a cross-sectional view showing a state in which the liquid injection port is sealed with a sealing plug.
The liquid injection port 7 is sealed with a sealing plug 8 after injecting an electrolytic solution. The sealing plug 8 includes a disc portion 8a that can be fitted into the concave portion 22 of the liquid injection port 7, and a convex portion 8b that protrudes from the lower surface of the disc portion 8a and can be fitted into the through hole 21 of the liquid injection port 7. A step surface 8c is formed between the disc portion 8a and the convex portion 8b. The step surface 8c contacts the concave bottom surface 23 of the liquid injection port 7.

  As for the sealing plug 8, the convex part 8b is fitted in the through-hole 21 of the liquid injection port 7, the disk part 8a is fitted in the concave part 22 of the liquid injection port 7, and the step surface 8c is the liquid injection port 7. The welded portion w is laser welded to the battery lid 3 so that the welded portion w is formed over the entire circumference along the boundary portion between the disc portion 8 a and the recessed portion 22 in a state of being in contact with the recessed portion bottom surface 23.

  As shown in FIG. 8, the sealing plug 8 is welded in a state where the stepped surface 8 c of the sealing plug 8 is in contact with the concave bottom surface 23 of the liquid injection port 7, so that the surface contact area is wider. The liquid injection port 7 can be reliably sealed. And since the level | step difference surface 8c of the sealing plug 8 and the recessed part bottom face 23 of the injection port 7 are contacted over the perimeter along the periphery of the through-hole 21, the reliability of sealing is improved. Can be made.

  According to the method of injecting the electrolytic solution in the present embodiment, the electrolytic solution can be prevented from adhering to the welded portion in the vicinity of the injection port 7, so that welding failure occurs when the sealing plug 8 is laser welded. Can eliminate the risk of occurrence.

  In the above-described embodiment, the case where the discharge is performed toward the narrow side wall surface PN on the negative electrode side that is the narrow side wall surface PN closer to the liquid injection port 7 is described as an example, but it is far from the liquid injection port 7. You may make it discharge toward the narrow side wall surface PN of the positive electrode side which is the narrow side wall surface PN of one side. When discharging toward the narrow side wall surface PN in the direction close to the liquid injection port 7, if the discharge speed is increased too much, the electrolyte rebounds in the battery can 2, and when the amount of rebound increases, the liquid injection port 7 There is a possibility to adhere to. In such a case, the rebound of the electrolyte in the battery can 2 is suppressed by discharging toward the narrow side wall surface PN on the positive electrode side which is the narrow side wall surface PN far from the liquid injection port 7. Thus, it is possible to effectively prevent the boiled electrolyte from adhering to the liquid injection port 7.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Square secondary battery 1A Battery member 2 Battery can 3 Battery cover 4 Electrode group 7 Injection port 8 Seal plug 21 Through hole 22 Recess 23 Recess bottom 200 Injection device 202 Injection passage 204 Exhaust passage 210 Sealed container 211 Case cover 212 Case 221 Injection nozzle 222 Insertion part 223 Discharge part 224 Direction conversion part

Claims (8)

A flat electrode group, a rectangular battery can that accommodates the electrode group in a posture in which a pair of flat surfaces of the electrode group extend vertically, a battery lid that closes an upper portion of the battery can, and the battery A method for producing a prismatic secondary battery having a liquid injection port for injecting an electrolytic solution into the battery can provided to be opened in a lid,
An injection nozzle is inserted into the battery can from the injection port, and the electrolyte solution is inserted from the injection nozzle between the electrode group and the battery lid toward one side in the width direction of the electrode group. A method for producing a prismatic secondary battery, comprising a liquid injection step of discharging and injecting the liquid into the battery can. The prismatic secondary battery includes a pair of wide side walls facing the pair of flat surfaces of the electrode group and a pair of narrow sides facing a pair of side end portions on both sides in the lateral width direction of the electrode group. And the liquid injection port is provided at a position deviated to one narrow side wall surface side of the battery lid,
2. The square-shaped two-part structure according to claim 1, wherein in the liquid injection step, the electrolyte solution is discharged toward a narrow side wall surface closer to the liquid injection port of the pair of narrow side wall surfaces. A method for manufacturing a secondary battery. The prismatic secondary battery includes a pair of wide side walls facing the pair of flat surfaces of the electrode group and a pair of narrow sides facing a pair of side end portions on both sides in the lateral width direction of the electrode group. And the liquid injection port is provided at a position deviated to one narrow side wall surface side of the battery lid,
2. The square two according to claim 1, wherein in the liquid injection step, the electrolyte solution is discharged toward a narrow side wall surface farther from the liquid injection port of the pair of narrow side wall surfaces. A method for manufacturing a secondary battery. A flat electrode group, a rectangular battery can that accommodates the electrode group in a posture in which a pair of flat surfaces of the electrode group extend vertically, a battery lid that closes an upper portion of the battery can, and the battery A rectangular secondary battery manufacturing apparatus having a liquid injection port for injecting an electrolytic solution into the battery can provided to be opened in a lid;
A liquid injection nozzle that is inserted into the battery can from the liquid injection port and discharges the electrolytic solution between the electrode group and the battery lid and toward one side in the width direction of the electrode group. An apparatus for manufacturing a rectangular secondary battery. The battery can has a pair of wide side wall surfaces facing a pair of flat surfaces of the electrode group, and a pair of narrow side wall surfaces facing a pair of side end portions on both sides in the lateral width direction of the electrode group. ,
The said injection nozzle has a discharge part opened toward one narrow side wall surface of said pair of narrow side wall surfaces, The manufacturing apparatus of the square secondary battery of Claim 4 characterized by the above-mentioned. The battery lid is provided with the liquid injection port at a position displaced to one side of the pair of narrow side wall surfaces,
6. The rectangular two-side body according to claim 5, wherein the discharge portion is provided to open toward a narrow side wall surface closer to the liquid injection port of the pair of narrow side wall surfaces. Secondary battery manufacturing equipment.   The liquid injection nozzle is inserted into the liquid injection port, the insertion portion through which the electrolytic solution is circulated, and a direction for converting the flow of the electrolytic solution that has passed through the insertion portion toward the discharge portion The square secondary battery manufacturing apparatus according to claim 6, further comprising a conversion unit.   8. The square according to claim 7, wherein the direction changing portion has an inclined surface or a concave curved surface that gradually moves toward the direction of the discharge portion as it moves downward from above the battery can. Secondary battery manufacturing equipment.

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