JP2010021104A - Method of manufacturing secondary battery - Google Patents

Abstract

To provide a secondary battery manufacturing method for obtaining a secondary battery that is prevented from being affected by gas generation at a low cost.
A liquid injection step in which a flat wound electrode body is placed in a rectangular parallelepiped battery case 12 in which a pair of wide surfaces 12m face each other, and an electrolyte is injected from an injection port formed in the battery case 12. A charging step of temporarily sealing and charging the inlet 15 after liquid injection, a degassing step of releasing the temporary sealing and removing the gas in the battery case 12 generated during the charging step, and the inlet 15 And an aging process in which the battery case 12 is placed at a predetermined temperature for a predetermined time, the pair of wide surfaces 12m of the battery case 12 are sandwiched from both sides, and the battery case 12 is pressed in the sandwiching direction. A method for manufacturing a secondary battery, wherein the charging step, the degassing step, and the aging step are executed.
[Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a secondary battery, and more particularly to a method for manufacturing a secondary battery in which the influence of gas generated in a charging process or an aging process is prevented.

  Lithium secondary batteries and the like have been put into practical use as power sources for mobile phones and personal computers, and the development of electric vehicles has been urgently promoted in the field of automobiles due to resource problems and environmental problems. Generally, in a lithium secondary battery, an electrode including a positive electrode and a negative electrode is inserted into a battery case, and after an electrolyte is injected, the lithium secondary battery is temporarily sealed and subjected to initial charging. Thereafter, so-called high-temperature aging treatment is performed for storage at a predetermined temperature. Further, degassing, main sealing, and room temperature aging are performed, and then inspection for leakage and the like is performed.

  In the manufacture of such a secondary battery, gas is generated in the charging process and the case is expanded, and thus degassing is performed. Further, since gas is generated in the subsequent aging process, the battery case expands and deforms, and there is a problem that the secondary battery cannot be installed in a predetermined space. Therefore, in the conventional manufacturing method, a method of performing degassing at the time of initial charging and after aging, or performing a degassing step collectively after aging has been adopted.

At that time, in order to prevent the deformation of the battery case due to expansion, for example, the following method has been proposed. Patent Document 1 below describes that pressing the wide surface of the battery case during charging and discharging is performed. Patent Document 2 below describes that the battery is installed in a pressure resistant container, and the secondary battery is initially charged while being pressurized with a high-pressure gas. In Patent Document 3 below, gas is generated even in the aging process after degassing and main sealing, and after discharging the gas generated by charging to the outside, the battery case is placed in a reduced pressure environment. In this, it is described that the inlet is fully sealed.
Japanese Patent Laid-Open No. 08-293320 JP 2005-85267 A JP 2004-30957 A

  In the secondary battery manufacturing method, as described above, it has been a problem to suppress the expansion deformation of the case due to the generation of gas. As a method for solving such a problem, as shown in Patent Documents 1 and 2, a surface that expands in a charging stage is mechanically pressed, expansion deformation is prevented by atmospheric pressure, and aging is further performed. In order to cope with gas generation in the treatment, a sealing process in a reduced pressure state as shown in Patent Document 3 has been performed. However, such a conventional problem solving method has a problem in that the manufacturing process of the secondary battery becomes complicated, and the manufacturing cost increases due to an increase in facilities and manufacturing processes therefor.

  Therefore, an object of the present invention is to provide a secondary battery manufacturing method for obtaining a secondary battery that prevents the influence of gas generation at low cost, in order to solve such a problem.

  A method for manufacturing a secondary battery according to the present invention includes a flat wound electrode body in a rectangular parallelepiped battery case having a pair of wide surfaces facing each other, and injecting an electrolytic solution from an inlet formed in the battery case. A liquid injection step, a charging step of temporarily sealing and charging the injection port after liquid injection, a degassing step of removing the gas in the battery case generated during the charging step by releasing the temporary sealing, And an aging process in which the inlet is fully sealed and placed at a predetermined temperature for a predetermined time, wherein the pair of wide surfaces of the battery case are sandwiched from both sides and the battery case is pressed in the sandwiching direction. The charging step, the degassing step, and the aging step are performed.

In the method for manufacturing a secondary battery according to the present invention, it is preferable that the restraint state presses the wide surface of the battery case with a predetermined pressure at the start of the charging step.
In the secondary battery manufacturing method according to the present invention, it is preferable that the restraint state continues without being unraveled through the charging step, the degassing step, and the aging step.
Further, in the method for manufacturing a secondary battery according to the present invention, the pair of restraining plates applied to the pair of wide surfaces are connected by a bolt in the sandwiching direction, and the restraining state is adjusted by a tightening condition of the bolt. preferable.

Further, in the method for manufacturing a secondary battery according to the present invention, a pair of restraint plates parallel to the pair of wide surfaces are connected by bolts in the sandwiching direction, one restraint plate is applied to one wide surface, and the other Preferably, an elastic member is provided between the constraining plate and the other wide surface, and the constraining state is adjusted by the elastic force of the elastic member.
Further, in the method for manufacturing a secondary battery according to the present invention, the liquid injection step is performed by placing the battery case in a vacuum-evacuated chamber, wherein the battery case has the pair of wide surfaces. Is preferably performed in the constrained state in which is inserted from both sides.

  In the method for manufacturing a secondary battery according to the present invention, after injecting an electrolyte solution into a battery case and temporarily sealing the battery case, the battery case is pressed and restrained during a charging process, a degassing process, and an aging process. did. In this case, the battery case may be restrained by, for example, pressing at a predetermined pressure from the start of the charging process, or initially expanded with gas generated in the charging process or the like with the pressing force set to zero. It may be configured to be in a pressed state as a reaction force of the pressure increase in the battery case. In the present invention, the secondary battery having an appropriate internal pressure can be manufactured at low cost by restraining the battery case in the course of the manufacturing process and suppressing the expansion.

  Next, embodiments of the method for manufacturing a secondary battery according to the present invention will be described below with reference to the drawings. FIG. 1 is an external perspective view showing the lithium ion secondary battery of the present embodiment. As shown in FIG. 1, the lithium ion secondary battery 10 of the present embodiment includes a flat wound electrode body 11 in a rectangular battery case 12 and includes a positive electrode terminal 13 and a negative electrode terminal 14. The battery case 12 is a sealed container in which a lid 12b is joined to a rectangular can 12a having a bottomed rectangular tube shape by laser seam welding. The positive terminal 13 and the negative terminal 14 protrude from the lid 12b of the battery case 12 as described above.

  The wound electrode body 11 is wound in a state where a separator is sandwiched between the positive electrode sheet and the negative electrode sheet with respect to the winding core. The thickness of such an electrode sheet or separator is about 0.1 mm, and about 100 layers of each sheet are wound around the core to form a cylindrical electrode winding body. And the positive electrode sheet and separator wound by the winding core are cut, The cut location is stopped by the winding stop tape, and it becomes an electrode winding body. Thereafter, the cylindrical shape is deformed into a flat shape by crushing with a press, and the flat wound electrode body 11 thus formed is inserted into the battery case 12.

  Next, an inlet 15 is formed between the terminals 13 and 14 in the battery case 12, and an electrolytic solution is injected from the inlet 15. The inlet 15 is temporarily sealed by a rubber plug 16 (see FIG. 2) provided for temporary sealing. Examples of the electrolytic solution include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate (VC), and chains such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylmer carbonate (EMC). A solution in which a supporting electrolyte such as LiPF6, LiCIO4, or LiBF4 is dissolved in a mixed organic solvent with a carbonate-like carbonate can be used.

  The rubber plug 16 that seals the injection port 15 is made of an ethylene-propylene copolymer (EPDM). Although rubber made of EPDM is used for the rubber plug 16, for example, chloroprene rubber, butyl rubber, silicon rubber, or fluorine-based rubber may be used. In addition, materials appropriately combining these may be used, and further, materials other than those shown above that have a property of being in contact with the lid with electrolyte resistance and gas resistance can be employed. is there. Note that both the liquid injection step and the temporary sealing step are performed in an environment having a dew point of −30 ° C. or less.

  Next, in the step after liquid injection, the battery case 12 is restrained by a restraining jig. FIG. 2 is a perspective view showing a state in which the battery case 12 is restrained by a restraining jig. The restraining jig 20 has two restraining plates 21 that sandwich the wide surface 12 m of the battery case 12 from both sides, and the restraining plates 21 are connected to each other by four bolts 22. The space between the restraining plates 21 is adjusted by the tightening condition of the bolts 22, and the restraining pressure for pressing the wide surface 12 m of the battery case 12 sandwiched therebetween is adjusted.

  In the present embodiment, the battery case 12 is restrained at a value at which the restraining pressure for pressing the wide surface 12m by the restraining plate 21 is 0.2 MPa. In this case, if the restraining pressure for restraining the battery case 12 is too low, sufficient restraining force does not reach the electrode body, voltage variation occurs in the surface, and in the worst case, lithium deposition may occur in the negative electrode. Because there is. Therefore, the constraint pressure is desirably 0.2 MPa or more.

  On the other hand, if the restraint pressure is too high, stress is applied to the joint between the square can 12a and the lid body 12b, and there is a risk of leakage. Moreover, if the strength of a porous body having ion permeability and electronic conductivity is restricted as a member in the electrode body, the voltage retention in an open circuit state is lost. Therefore, the upper limit of the surface pressure generated on the wide surface 12m by the constraint is set according to the bonding strength of the battery case 12 and the strength of the porous body. In the present embodiment, charging is performed so that the surface pressure of the wide surface 12m of the battery case 12 by the restraining jig 20 is up to 1.0 MPa.

  Subsequently, initial charging is performed in the charging step. When the lithium ion secondary battery 10 is initially charged in this charging step, the inside of the battery case 12 tends to expand due to the gas generated as lithium ions are inserted into the negative electrode. However, in the present embodiment, while the wide surface 12m of the battery case 12 tries to swell from the inside, the restraining jig 20 restrains the outside, so that deformation of the battery case 12 due to expansion is suppressed. Yes. Therefore, the pressure is increased inside the battery case 12, and the initial charging is stopped at such a voltage that the surface pressure of the wide surface 12m becomes 1.0 MPa or more.

  Since the surface pressure of the constrained wide surface 12m increases in proportion to the charging voltage, the initial charging may be stopped based on the voltage. More specifically, when the cyclic voltammetry of a secondary battery is measured at two terminals, the vicinity of a voltage that becomes the final reaction peak within the voltage at which the electrolytic solution decomposes is desirable. In the present embodiment, the surface pressure of the wide surface 12 m was 1.0 MPa when charged to 4.1 V.

  After the filling of the electrolytic solution is completed, the process proceeds to the degassing step and the main sealing step. In the past, the battery case 12 is still pressed by the restraining jig 20 on both sides of the opposing wide surface 12m. In this state, the temporarily sealed rubber plug 16 is removed from the lithium ion secondary battery 10, and gas is vented from the inlet 15. Then, the main sealing is performed next with the restraining jig 20 pressing the battery case 12. In this sealing, an aluminum plate is covered so as to cover the injection port 15 of the battery case 12, and the aluminum plate and the lid 12b are welded by laser welding. Note that both the degassing step and the main sealing step are performed in an environment having a dew point of −30 ° C. or lower.

  By the way, after such a main sealing step is finished, the restraint by the restraining jig 20 may be released according to circumstances, and then restrained again. For example, in this case, the restraining jig 20 may be replaced, or the restraint may be temporarily released for sealing leakage inspection and then restrained again.

  Thereafter, the next high temperature aging process and room temperature aging process are performed while the battery case 12 is restrained by the restraining jig 20. In the high temperature aging, a break-in is performed in which the lithium ion secondary battery 10 is placed at a high temperature of 50 ° C. for 15 hours. Further, in the subsequent room temperature aging, the lithium ion secondary battery 10 is conditioned for 10 days at 25 ° C. at room temperature. During this time, some gas is generated and the pressure rises inside the battery case 12.

  In the subsequent inspection process, after the voltage of the lithium ion secondary battery 10 was adjusted to 3.726 V, the lithium ion secondary battery 10 was discharged at a current equivalent to 4 C, and the resistance after 10 seconds (= voltage drop amount / discharge current for 10 seconds) was measured. Inspection is performed. And after completion | finish of a test | inspection, the restraining jig | tool 20 is removed from the lithium ion secondary battery 10, and the battery case 12 is cancelled | released from a restraint state.

  By the way, in this embodiment, since the restraining jig 20 restrains the wide surface 12m of the battery case 12 in a pressed state, the inside of the battery case 12 after degassing and main sealing is negative pressure. It is in a state. Therefore, even if gas is generated in the battery case 12 in the subsequent aging process, the atmospheric pressure rises almost by the negative pressure. Therefore, the wide surface 12m of the battery case 12 does not swell after the restraining jig 20 is removed. And the lithium ion secondary battery 10 confirms the pressure in the battery case 12 after the manufacture, The result is mentioned later.

  Therefore, according to the method for manufacturing a secondary battery according to the present embodiment, a predetermined restraining pressure (in this embodiment) is applied by the restraining jig 20 through the charging process, the degassing / main sealing process, and the high temperature / room temperature aging process. 0.2 MPa), the expansion of the battery case 12 in the charging process is suppressed, and the expansion due to the gas generated in the aging process is absorbed by creating a negative pressure state. The secondary battery 10 was able to be manufactured. The lithium ion secondary battery 10 in which the expansion of the battery case 12 due to the generated gas is suppressed can be provided at a low cost by a very simple method using the restraining jig 20.

  Next, FIG. 3 is a perspective view showing a state in which the battery case 12 is restrained by another restraining jig in the secondary battery manufacturing method according to the present embodiment. In the restraining jig 30, two restraining plates 31 that sandwich the wide surface 12 m of the battery case 12 from both sides are connected by four bolts 32. In this embodiment, a long bolt 32 is used, and a spring unit 35 is sandwiched between the two restraining plates 31 together with the battery case 12.

  In the spring unit 35, two pressing plates 36 are connected by a plurality of coil springs 37. As shown in the figure, the spring unit 35 sandwiched between the two restraint plates 31 together with the lithium ion secondary battery 10 is installed in a state where the coil spring 37 is compressed. The wide surface 12m of the case 12 is pressed. At this time, the restraining jig 30 is set so that the restraining pressure that presses the wide surface 12 m is, for example, 0.2 MPa, depending on the distance between the restraining plates 31 and the spring force of the coil spring 35. Furthermore, as described above, the surface pressure of the wide surface 12m is increased by the gas generated during charging. In this embodiment, the maximum surface pressure is adjusted not to exceed 0.5 MPa by the elastic force of the coil spring 37 in this embodiment. Has been.

  Therefore, when initial charging is performed on the lithium ion secondary battery 10 in a restrained state in the charging process, gas is generated as described above, and thereby the inside of the battery case 12 tends to expand. However, since the wide surface 12m of the battery case 12 tends to swell from the inside, it is pressed from the outside by the restraining jig 30, so that deformation due to expansion is suppressed. And the restraining jig | tool 30 of this embodiment does not exceed 0.5 MPa even if the coil spring 37 contracts and the surface pressure of the wide surface 12m rises as the pressure inside the battery case 12 increases.

  After the filling of the electrolytic solution is completed, the degassing step and the main sealing step are performed. During this time, the battery case 12 is still pressed by the restraining jig 30 on both sides of the wide surface 12m facing each other. In this state, the temporarily sealed rubber plug 16 is removed from the lithium ion secondary battery 10, the gas is removed from the inlet 15, and the main sealing is performed.

  In this sealing, an aluminum plate is covered so as to cover the injection port 15 of the battery case 12, and the aluminum plate and the lid 12b are welded by laser welding. The degassing step and the main sealing step are both performed in an environment with a dew point of −30 ° C. or lower. If it is after this sealing process is complete | finished, the restraint by the restraining jig | tool 30 may be cancelled | released depending on the case, and you may restrain again after that. For example, in this case, the restraining jig 30 may be replaced, or the restraint may be temporarily released for sealing leakage inspection, and then restrained again.

  Thereafter, the next high temperature aging process or room temperature aging process is performed while being restrained by the restraining jig 30. In the high temperature aging, a break-in is performed in which the lithium ion secondary battery 10 is placed at a high temperature of 50 ° C. for 15 hours. Further, in the subsequent room temperature aging, the lithium ion secondary battery 10 is conditioned for 10 days at room temperature of 25 ° C. During this time, some gas is generated and the pressure rises inside the battery case 12. In the subsequent inspection process, after the voltage of the lithium ion secondary battery 10 is adjusted to 3.726 V, the battery is discharged with a current corresponding to 4 C, and the resistance is measured after 10 seconds. And after completion | finish of a test | inspection, the restraining jig | tool 30 is removed from the lithium ion secondary battery 10, and the battery case 12 is cancelled | released from a restraint state.

  By the way, since the restraining jig 30 restrains the wide surface 12m of the battery case 12 in a pressed state, the degassed lithium ion secondary battery 10 is sealed with the inside of the battery case 12 in a negative pressure state. . Even if gas is generated in the subsequent aging process, the pressure rise is almost equal to the negative pressure. Therefore, when the restraining jig 30 is subsequently released, the wide surface 12m of the battery case 12 does not swell due to the gas generated in the aging process. And the lithium ion secondary battery 10 confirms the pressure in the battery case 12 after the manufacture.

  Therefore, according to the method for manufacturing a secondary battery according to the present embodiment, a predetermined restraining pressure (in this embodiment) is applied by the restraining jig 300 through the charging process, the degassing / main sealing process, and the high temperature / room temperature aging process. 0.2 MPa), the expansion of the battery case 12 in the charging process is suppressed, and the expansion due to the gas generated in the aging process is absorbed by creating a negative pressure state. The secondary battery 10 was able to be manufactured. The lithium ion secondary battery 10 in which the expansion of the battery case 12 due to the generated gas is suppressed can be provided at a low cost by an extremely simple method using the restraining jig 300.

Here, about the lithium ion secondary battery 10 manufactured by changing constraint conditions, the internal pressure after inspection, the dispersion | variation in resistance, and lithium precipitation were confirmed. FIG. 4 is a table showing the results of each constraint condition.
Restraint condition 1 is a case where the initial restraint pressure is kept at 0.2 MPa by the restraint jig 20 in FIG. 2, and the restraint condition 2 is that the initial restraint pressure is 0. 0 by the restraint jig 30 in FIG. 3. This is a case where the pressure is 2 MPa and the coil spring 37 is restrained so that the restraining pressure at the time of main sealing is suppressed to 0.5 MPa. And the restraint condition 3 is a case where the restraint jig 20 keeps restraint by raising the initial restraint pressure to 0.5 MPa.

  The constraint condition 4 is a case where the initial constraint pressure is restrained by the restraining jig 20 at 0.2 MPa, and the restraint is once released and re-restrained. The restraint condition 5 is a case where the restraint jig 20 continues to restrain the initial restraint pressure to 0.1 MPa. The restraint condition 6 is a case where the restraint jig 30 continues to restrain the initial restraint pressure at 0.2 MPa, and the restraint pressure at the time of main sealing is suppressed to 0.4 MPa by setting the coil spring 37. The constraint condition 7 is the same as the constraint condition 3 in that the initial constraint pressure is increased to 0.5 MPa by the constraint jig 20 and the constraint is continued, but this is the case where the main sealing is performed after high temperature aging.

  From the result of FIG. 4, the pressure in the battery case 12 after the inspection is reduced to zero by continuing to restrain the battery case 12 that expands with a restraint pressure of a certain level or more as in the restraint conditions 1 and 2 shown in the embodiment. It was found that the following can be suppressed. That is, by continuing the restraint, it is possible to obtain the lithium ion secondary battery 10 that does not eventually swell the battery case 12 even after gas generation during initial charging or aging. This can be understood from the result of constraint condition 3 where the constraint pressure is high.

  On the other hand, it can be seen that the restraint condition 4 in which the restraint is released during the manufacturing process and the restraint condition 6 in which the restraint pressure at the time of main sealing is set to a low value causes the internal pressure to increase and the battery case 12 to expand somewhat. Therefore, it can be seen that the restraint by the restraining jigs 20 and 30 is preferably continued from the initial charging until the aging is completed. Further, in the case of restraint condition 5 with an initial restraining force of 0.1 MPa, it is necessary to restrain at a pressure equal to or higher than a predetermined value because lithium has precipitated although the internal pressure has become negative. I understood that. In the case of the constraint condition 6 and the constraint condition 7, the variation in resistance is large.

  Here, FIG. 5 is a graph showing values measured for each step of the internal pressure change of the battery case 12 for the lithium ion secondary battery 10 manufactured under the constraint conditions 1 and 4, and the internal pressure is plotted on the vertical axis. Each manufacturing process is shown on the horizontal axis. The time points shown on the horizontal axis are S1 before charging, S2 after initial charging, S3 after degassing main sealing, S4 after high temperature aging, S5 after room temperature aging, and S6 after releasing the restraint. In the restraint conditions 1 and 4, the initial restraint pressure at the time S1 is 0.2 MPa, and the pressure is increased to 0.5 MPa by the gas generated by the initial charge.

  And in restraint condition 4, internal pressure changed with the positive value after S3 time which performed degassing main sealing by releasing restraint after that. On the other hand, in restraint condition 1 that continued to be restrained, the pressure increased temporarily at S4 after high-temperature aging from S3 when the internal pressure became negative after degassing and main sealing, but the internal pressure never became positive. It was. Therefore, from the above results, it is preferable that the constraint condition is that the initial constraint pressure is not less than a predetermined value (for example, 0.2 MPa) and that the constraint condition is a rigid structure like the constraint jig 20. However, since the voltage retention in the open circuit state is lost if the restraining force is too large, in such a case, a configuration such as the restraining jig 30 is also effective for limiting the maximum value of the restraining force. Further, as a constraint condition, it is preferable that the constraint is continued without being released halfway.

  By the way, when injecting the electrolyte into the battery case 12, it is preferable to evacuate the periphery in order to improve the permeability of the solution to the wound electrode body 11 (FIG. 1). However, in a vacuum state, the battery case 12 swells outward, and the gap between the electrode sheet and the separator constituting the wound electrode body 11 is enlarged. When the electrolyte solution is injected in such a state, foreign matter such as spatter generated when laser can seam welding the rectangular can 12a and the lid body 12b enters the gap between the wound electrode bodies 11 together with the electrolyte solution. There is a fear. As a result, the quality of the lithium ion secondary battery 10 is degraded, such as causing a short circuit.

  Therefore, in the above embodiment, the manufacturing method in which the lithium ion secondary battery 10 after the liquid injection is restrained by the restraining jig 20 has been described. However, when the electrolytic solution is injected into the battery case 12, the restraining jig 20 or the like is used. It is preferable to restrain. Therefore, this embodiment demonstrates the case where the lithium ion secondary battery 10 is restrained also in the injection | pouring process of electrolyte solution.

  FIG. 6 is a diagram showing a step of injecting the electrolyte into the battery case 12. In this liquid injection process, the lithium ion secondary battery 10 restrained by the restraining jig 20 is placed in the chamber 41, and the liquid supply pipe 42 is connected to the inlet 15 formed in the battery case 12. In the embodiment described above, the restraining jig 20 applies a restraining pressure of 0.2 MPa, for example, to the battery case 12, but a lower value may be used, and it is desirable that the restraining jig 20 be 0.1 MPa or more. This is because it is necessary to improve the permeability of the electrolytic solution to the wound electrode body 11 while preventing the battery case 12 from expanding more than necessary.

  Therefore, in the liquid injection process, the chamber 41 is evacuated by a vacuum pump (not shown) through the vacuum tube 43 having the valve 44 opened, and the valve 44 is closed and the chamber 41 is kept in a reduced pressure state. It is. Therefore, in the lithium ion secondary battery 10, the outer side of the battery case 12 has a negative pressure from the inner side and the wide surface 12 m of the battery case 12 tends to widen, but is restricted by the restraining jig 20. In this state, the valve 45 of the liquid supply pipe 41 is opened, and the electrolytic solution in the tank 46 is sent to the battery case 12 in the chamber 41. And when releasing restraint after completion of liquid injection, it releases at a slow speed of 0.01 MPa / second, for example, and suppresses the flow of the electrolyte between the electrodes.

  According to the present embodiment, since the battery case 12 in the chamber 41 evacuated by the restraining jig 20 is prevented from expanding, foreign matters such as spatter together with the electrolytic solution are formed on the electrode sheet constituting the wound electrode body 11. It becomes possible not to enter the gap, and quality deterioration of the lithium ion secondary battery 10 can be prevented.

As mentioned above, although embodiment was described about the manufacturing method of the secondary battery which concerns on this invention, this invention is not limited to this, A various change is possible in the range which does not deviate from the meaning.
In the above-described embodiment, the case where the battery case 12 is positively pressed by pressing is described. For example, initially, the pressing force is set to zero and the battery case 12 is pressed by a reaction force that is expanded by the generated gas. You may do it.
For example, in the restraining jig 30 shown in FIG. 3, the spring unit 35 is used. However, instead of the coil spring 37, a rubber unit using rubber may be used.

It is the external appearance perspective view which showed the lithium ion secondary battery. It is the perspective view which showed the state which restrained the battery case with the one restraining jig. It is the perspective view which showed the state which restrained the battery case with the other restraining jig | tool. It is the figure which showed the result of the internal pressure of the lithium ion secondary battery manufactured by changing restraint conditions, the dispersion | variation in resistance, and the precipitation result of lithium. It is the figure which made the value which measured the internal pressure change of the battery case for every process about the lithium ion secondary battery manufactured with the manufacturing method from which constraint conditions differ, in the graph. It is the figure which showed the state which inject | pours electrolyte solution into a battery case in a vacuum chamber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Lithium ion secondary battery 11 Winding electrode body 12 Battery case 13 Positive electrode terminal 14 Negative electrode terminal 12m Wide surface 15 Inlet 16 Rubber stopper 20 Restraint jig 21 Restraint plate 22 Bolt

Claims (6)

A flat wound electrode body is placed in a rectangular parallelepiped battery case with a pair of wide surfaces facing each other, a liquid injection step of injecting an electrolyte from the injection port formed in the battery case, and the injection port after the liquid injection A charging step for temporarily sealing and charging, a degassing step for removing the gas in the battery case generated during the charging step by releasing the temporary sealing, and a predetermined sealing and sealing at the predetermined temperature In the manufacturing method of the secondary battery having an aging process that is time-detained,
Manufacturing the secondary battery, wherein the charging step, the degassing step, and the aging step are performed in a restrained state where the pair of wide surfaces of the battery case are sandwiched from both sides and the battery case is pressed in the sandwiching direction. Method. In the manufacturing method of the secondary battery according to claim 1,
In the restraint state, the wide surface of the battery case is pressed with a predetermined pressure at the start of the charging step. In the manufacturing method of the secondary battery according to claim 1 or 2,
The method of manufacturing a secondary battery, wherein the restraint state continues without being solved through the charging process, the degassing process, and the aging process. In the manufacturing method of the secondary battery according to any one of claims 1 to 3,
A method of manufacturing a secondary battery, comprising: connecting a pair of restraint plates applied to the pair of wide surfaces by bolts in the sandwiching direction; and adjusting the restraint state according to a tightening condition of the bolts. In the manufacturing method of the secondary battery according to any one of claims 1 to 3,
A pair of constraining plates parallel to the pair of wide surfaces are connected by bolts in the sandwiching direction, one constraining plate is applied to one wide surface, and an elastic member is provided between the other constraining plate and the other wide surface. Is provided, and the restraint state is adjusted by the elastic force of the elastic member. In the manufacturing method of the secondary battery according to any one of claims 1 to 5,
The liquid injection step is performed by placing the battery case in a vacuum-evacuated chamber, wherein the battery case is performed in the constrained state with the pair of wide surfaces sandwiched from both sides. A method for producing a secondary battery.

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