JP6260318B2 - Power storage device manufacturing method and power storage device inspection method - Google Patents

Description

  The present invention relates to an electrode assembly, a method for manufacturing a power storage device including an electrolytic solution in a case, and a method for inspecting the power storage device.

  Power storage devices such as secondary batteries and capacitors are widely used as power sources because they can be recharged and can be used repeatedly. Generally, as a secondary battery (power storage device) having a large capacity, an electrolytic solution and an electrode assembly in which a sheet-like positive electrode and a negative electrode are stacked with a separator interposed therebetween are provided in a case. There is something.

  In the secondary battery, the ions in the electrolytic solution pass through the pores of the separator and reciprocate between the active material of the positive electrode and the negative electrode, whereby the secondary battery is charged and discharged. In such a secondary battery, air may remain in the pores in at least one of the separator and the active material layer of each electrode, and the electrolyte may be manufactured without being impregnated in each active material or separator. When the electrolyte of each active material or separator is not impregnated with electrolyte, the amount of ions that can reciprocate between the positive electrode and the negative electrode decreases, so the performance of the secondary battery (for example, operating voltage or Electric capacity) will be reduced.

  Therefore, at the time of manufacturing the secondary battery, after impregnating the electrolytic solution, it is determined whether or not the electrolytic solution is sufficiently impregnated in the electrode assembly (see, for example, Patent Document 1). In Patent Document 1, after performing the step of impregnating the electrode assembly with the electrolytic solution, the secondary battery is tilted. At this time, if the electrode assembly is not impregnated with the electrode assembly, the electrolyte solution accumulates between the outer peripheral surface of the electrode assembly and the inner surface of the case, and the electrolyte solution accumulates, so that the weight balance of the secondary battery is biased. Then, grasp the degree of deviation of the weight balance, compare the degree of deviation with a preset target value, and determine that the impregnation is sufficient if the degree of deviation is equal to or less than the target value. Is too large, it is determined that the impregnation is insufficient.

JP 2009-48964 A

  However, the electrode assembly includes a laminated type and a wound type. Since the wound electrode assembly as in Patent Document 1 is obtained by winding the positive electrode and the negative electrode in a spiral shape, the outer peripheral surface is curved, and the outer peripheral surface of the wound electrode assembly And a relatively large space is easily formed between the inner surface of the case in which each surface forms a rectangle, in particular, between the rounded portion of the wound electrode assembly and the inner surface of the case. For this reason, when determining the impregnation of the electrolytic solution, if the secondary battery is tilted as in Patent Document 1, the electrolytic solution accumulates in the space, and the weight balance becomes large. Therefore, it is easy to grasp the impregnation state of the electrolytic solution from the large weight balance. However, the stacked electrode assembly is pressurized so that the positive electrode, the negative electrode, and the separator are in close contact with each other, and the both end surfaces and the bottom surface in the stacking direction of the electrode assembly are in close contact with the inner surface of the case. Housed in a case. Further, it does not have a rounded portion like a wound electrode assembly. For this reason, in the stacked type secondary battery, even when the secondary battery is tilted as in Patent Document 1, it is difficult for the electrolyte to accumulate, and even if the electrolyte is not sufficiently impregnated, it is difficult to detect an imbalance in the weight balance. It is difficult to determine whether the electrolyte is sufficiently impregnated.

  An object of the present invention is to provide a method for manufacturing a power storage device and a method for inspecting a power storage device that can improve versatility.

A method of manufacturing a power storage device for solving the above problems includes an electrode assembly in which electrodes of different poles are alternately stacked in a state of being insulated from each other, and a power storage device including an electrolytic solution in a metal case. A manufacturing method comprising: an injection step of injecting the electrolytic solution into the case; an impregnation step of impregnating the electrode assembly with the electrolytic solution; and after the impregnation step and before the aging step. And an impregnation inspection step for determining whether or not the electrode assembly is sufficiently impregnated with the electrolyte solution, wherein the impregnation inspection step is performed in a state where the measurement coil is brought close to the wall portion of the case. An alternating current is passed through the measurement coil to generate an eddy current in the wall portion of the case, and the penetration depth of the eddy current is deeper than the thickness of the wall portion of the case where the measurement coil is approached. the thickness of the wall portion of the case to And sets the frequency of the alternating current in accordance with the material of the case, the change of the eddy current varies depending on the presence or absence of voids or spaces present between the inner surface and the outer surface of the electrode assembly of a wall portion of said case The gist of the present invention is to determine the impregnation state of the electrode assembly into the electrode assembly.

  According to this, after the impregnation step, when the electrode assembly is sufficiently impregnated with the electrolytic solution, a gap exists between the inner surface of the wall portion and the outer surface of the electrode assembly. In this state, when the impregnation inspection process is performed, the measurement coil is brought close to the wall portion and an eddy current is generated in the wall portion, there is no electrolyte solution facing the inner surface of the wall portion. Limited to walls. For this reason, the current flowing through the measuring coil does not change from the value when the eddy current is generated in the wall portion, and it is determined that the electrode assembly is sufficiently impregnated with the electrolyte.

  On the other hand, after the impregnation process, if the electrode assembly is not sufficiently impregnated with the electrode assembly, the space between the inner surface of the wall portion and the outer surface of the electrode assembly is filled with the electrolyte solution, and there is no slight gap. In this state, when the impregnation inspection process is performed, the measuring coil is brought close to the wall and an eddy current is generated in the wall, the eddy current generated is caused by the presence of the electrolyte facing the inner surface of the wall. It occurs up to a deeper position than when there is no. For this reason, the current flowing through the measurement coil changes from the value when the eddy current is generated only in the wall portion, and based on this change, it is determined that the electrolyte assembly is not sufficiently impregnated in the electrode assembly. .

  Therefore, even in a power storage device having a stacked electrode assembly that does not accumulate electrolyte even when the power storage device is tilted, whether or not the electrolyte is sufficiently impregnated based on the presence or absence of a small gap is determined. Can be determined. In a power storage device having a wound electrode assembly, a relatively large space is formed between the inner surface of the wall and the outer surface of the electrode assembly. Whether it is sufficient or not can be determined. Therefore, it can be determined whether or not the electrolyte is sufficiently impregnated regardless of the form of the electrode assembly, and versatility can be improved. Moreover, the frequency of the alternating current passed through the measuring coil is set according to the thickness of the case wall and the material of the wall. For this reason, the impregnation inspection process according to the thickness of the wall part of a case and the material of a wall part can be performed, and versatility can be improved.

In the method for manufacturing the power storage device, the measurement coil is connected to a bridge circuit that converts a change in current induced in the measurement coil in response to the eddy current into a change in impedance, and the impregnation test is performed. In the step, the impregnation state of the electrode assembly with the electrolytic solution may be determined based on the impedance value obtained by the generated eddy current.
Moreover, about the manufacturing method of an electrical storage apparatus, the said case may have the bottom wall as said wall part, and may set the said frequency so that the said penetration depth may become deeper than the thickness of the said bottom wall.
According to this, if the electrolyte solution is not sufficiently impregnated in the electrode assembly, the electrolyte solution accumulates on the bottom wall of the case by its own weight. For this reason, it is easy to carry out a method of determining whether the measurement coil is sufficiently impregnated by bringing the measuring coil close to the bottom wall.

  In the method of manufacturing the power storage device, the case has side walls facing both ends in the stacking direction of the electrode assembly, and the measurement coil is scanned along the side walls as the wall portions, You may determine whether the said electrolyte solution was impregnated in the lamination direction of the assembly.

  According to this, when the active material of the electrode assembly or the pores of the separator are impregnated with the electrolytic solution, the pores of the electrode assembly are filled with the electrolytic solution, and there are no voids. In this state, when the measurement coil is scanned on the side wall located in the stacking direction, the depth of the generated eddy current changes depending on the presence or absence of a gap, and the current flowing through the measurement coil changes. By detecting this change in current, it is determined whether or not the electrolyte assembly is sufficiently impregnated in the electrode assembly.

  Also, a method for inspecting a power storage device to solve the above problems includes an electrode assembly in which electrodes of different poles are alternately stacked with the electrodes insulated from each other, and a power storage device inspection including an electrolyte solution in a case A method for determining whether or not the electrolyte solution has leaked from the electrode assembly, wherein the inspection step is performed in a state where the measurement coil is brought close to the wall of the case. An alternating current is passed through the measurement coil to generate an eddy current in the wall portion of the case, and the penetration depth of the eddy current is deeper than the thickness of the wall portion of the case where the measurement coil is approached. And determining whether or not the electrolytic solution is leaking from the electrode assembly by setting the frequency of the alternating current.

  According to this, this inspection process is performed, for example, after the power storage device has been used for a predetermined time. If the electrode assembly is sufficiently impregnated with the electrolyte during the inspection, a gap or space is defined between the inner surface of the wall portion and the outer surface of the electrode assembly. In this state, when the inspection process is performed, the measuring coil is brought close to the wall portion and an eddy current is generated in the wall portion, there is no electrolyte solution facing the inner surface of the wall portion. Limited to part. For this reason, the current flowing through the measuring coil does not change from the value when the eddy current is generated in the wall, the depth of the generated eddy current is limited, and the current flowing through the measuring coil is a predetermined value. Thus, it is determined that the electrolyte is not leaking.

  On the other hand, for example, when the power storage device vibrates during use, the electrolyte leaks from the electrode assembly, and the impregnation is insufficient, electrolysis occurs between the inner surface of the wall portion and the outer surface of the electrode assembly. Liquid is present and the above-mentioned voids and spaces are not present. In this state, when the inspection process is performed, the measuring coil is brought close to the wall and an eddy current is generated in the wall, the generated eddy current is caused by the presence of the electrolyte facing the inner surface of the wall. It occurs up to a deeper position than there is no. For this reason, the current flowing through the measurement coil changes from the value when an eddy current is generated only in the wall, and it is determined that the electrolyte is leaking based on this change.

  Therefore, whether or not the electrolyte has leaked from the electrode assembly even in a power storage device having a stacked electrode assembly in which the electrolyte does not accumulate even when the power storage device is tilted, that is, the electrolyte It can be determined whether or not the solid is sufficiently impregnated. In a power storage device including a wound electrode assembly, a relatively large space is formed between the inner surface of the wall portion and the outer surface of the electrode assembly. It can be determined whether the assembly has leaked. Therefore, regardless of the form of the electrode assembly, it can be determined whether the electrolyte is leaking from the electrode assembly, and versatility can be improved. Moreover, the frequency of the alternating current passed through the measuring coil is set according to the thickness of the case wall and the material of the wall. For this reason, the inspection process according to the thickness of the wall part of a case and the material of a wall part can be performed, and versatility can be improved.

  According to the present invention, versatility can be improved.

The disassembled perspective view which shows the secondary battery of embodiment. The perspective view which shows the external appearance of the secondary battery of embodiment. The figure which shows an inspection apparatus. Graph showing the relationship between penetration depth and frequency. (A) is a figure which shows the state which test | inspects the secondary battery fully impregnated with electrolyte solution, (b) is the figure which shows the state which test | inspects the secondary battery which electrolyte solution is not fully impregnated. (A) is a fragmentary sectional view which shows the bottom wall side of the secondary battery fully impregnated with electrolyte solution, (b) is a fragmentary sectional view which shows the bottom wall side of the secondary battery not fully impregnated with electrolyte solution. The table | surface which shows the relationship of the impregnation state of electrolyte solution, the presence or absence of a space | gap, and an impedance. Sectional drawing which shows the state which test | inspects a secondary battery provided with the winding type electrode assembly. Sectional drawing which shows another example of the inspection method of a secondary battery provided with the laminated | stacked electrode assembly. The table | surface which shows the relationship of the impregnation state of electrolyte solution, the presence or absence of a space | gap, and an impedance. The table | surface which shows the relationship between the presence or absence of leakage of electrolyte solution, the presence or absence of space | gap and space, and impedance.

Hereinafter, an embodiment in which a method for manufacturing a power storage device is embodied in a method for manufacturing a secondary battery will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the secondary battery 10 includes a case 11, and the case 11 accommodates an electrode assembly 12 and an electrolytic solution (not shown). The case 11 includes a bottomed square cylindrical case main body 13 and a rectangular flat lid 14 that closes an opening 13 a for inserting the electrode assembly 12 into the case main body 13. Both the case body 13 and the lid body 14 are made of metal (stainless steel). The secondary battery 10 is a prismatic battery and is a lithium ion battery. The case body 13 includes a rectangular plate-shaped bottom wall 13b, a first side wall 13c erected from a pair of first side edges (short side edges) of the bottom wall 13b, and another pair of second sides of the bottom wall 13b. And a second side wall 13d erected from the edge (long side edge).

  A positive electrode terminal 15 and a negative electrode terminal 16 are electrically connected to the electrode assembly 12. A ring-shaped insulating member 17 for insulating from the case 11 is attached to each of the positive terminal 15 and the negative terminal 16. One end of each of the positive electrode terminal 15 and the negative electrode terminal 16 is exposed to the outside of the case 11 from the lid body 14.

  As shown in FIG. 6A, the electrode assembly 12 includes a positive electrode 21 and a negative electrode 24 of different poles, and a separator 27 that insulates the positive electrode 21 and the negative electrode 24 from each other. The positive electrode 21 includes a positive electrode active material layer 21b on both surfaces of a positive metal foil 21a (aluminum foil). The negative electrode 24 includes a negative electrode active material layer 24b on both surfaces of a negative electrode metal foil 24a (copper foil). The electrode assembly 12 is a stacked type in which a plurality of positive electrodes 21 and a plurality of negative electrodes 24 are alternately stacked, and a separator 27 is interposed between the electrodes.

  The positive electrode active material layer 21b on the positive electrode 21, the negative electrode active material layer 24b on the negative electrode 24, and the separator 27 are porous bodies, and the internal pores are impregnated with an electrolytic solution. The electrolytic solution is injected into the case 11 by an amount that fills the pores inside the electrode assembly 12.

  As shown in FIGS. 1 and 5A, in the lid body 14, a surface facing the inside of the case 11 is an inner wall surface 14a, and a surface facing the outside of the case 11 is an outer wall surface 14b. The lid 14 includes a circular liquid injection hole 14c penetrating in the thickness direction. The liquid injection hole 14 c is sealed by the sealing member 20.

Next, an inspection apparatus that determines whether or not the electrode assembly 12 is sufficiently impregnated with the electrolyte will be described.
As shown in FIG. 3, the inspection device 30 displays a measurement coil 31, a transmitter 32 that causes an alternating current to flow through the measurement coil 31, a bridge circuit 33 connected to the measurement coil 31, and a change in impedance. Display 34. The measurement coil 31 is used in the case 11 while being close to the bottom wall 13 b of the case body 13. By passing an alternating current through the measuring coil 31, a magnetic field is induced in the measuring coil 31, and when the magnetic flux is applied to the outer surface of the bottom wall 13b at a right angle, an eddy current is generated in the bottom wall 13b.

  The transmitter 32 can change the frequency of the alternating current that flows through the measuring coil 31. When an eddy current is generated in the bottom wall 13b, the amount of current flowing through the bottom wall 13b becomes weaker as the distance from the measuring coil 31 increases. In the present embodiment, it is important that the eddy current is formed beyond the thickness of the bottom wall 13b in order to determine whether or not the electrolytic solution is accumulated on the bottom wall 13b of the case 11. For this reason, the depth of eddy current, the so-called penetration depth, is set so that the penetration depth of eddy current is deeper than the thickness of the bottom wall 13b.

  As shown in FIG. 4, the penetration depth of the eddy current differs depending on the frequency of the alternating current flowing through the measuring coil 31 and the material of the metal on which the eddy current is formed. And in this embodiment, in order to obtain the penetration depth N deeper than the thickness of the bottom wall 13b in the stainless steel bottom wall 13b, the frequency M is set.

  As shown in FIG. 3, the bridge circuit 33 of the inspection apparatus 30 converts a change in current into a change in impedance when the current flowing through the measurement coil 31 changes. The display 34 displays the impedance value and whether or not the impedance value is an appropriate value. The appropriate impedance value is the impedance value detected when no electrolyte remains in the case 11, that is, when an eddy current is generated only in the bottom wall 13b. It is set in advance.

Next, the manufacturing method of the secondary battery 10 will be described together with the operation of the impregnation inspection process.
First, the electrode assembly 12 is inserted into the case body 13 from the opening 13 a of the case body 13. At this time, the electrode assembly 12 is pressurized so that the positive electrode 21 and the negative electrode 24 and the separator 27 are in close contact with each other, and both end surfaces of the electrode assembly 12 in the stacking direction are the second of the case body 13. The case body 13 is accommodated so as to be in close contact with the inner surface of the side wall 13d. Next, the lid body 14 is joined to the case body 13 to close the opening 13 a of the case body 13. Then, the process of housing the electrode assembly 12 in the case 11 is completed. Next, an injection process of injecting an electrolytic solution into the case 11 from the liquid injection hole 14 c is performed, and then the liquid injection hole 14 c is sealed with the sealing member 20. Then, an impregnation step of impregnating the electrode assembly 12 with the electrolytic solution is performed for a predetermined time.

After performing the impregnation step for a predetermined time, an impregnation inspection step is performed to determine whether or not the electrode assembly 12 is sufficiently impregnated with the electrolyte.
First, based on the graph shown in FIG. 4, the frequency M of the alternating current flowing through the measuring coil 31 is selected so that the penetration depth N exceeding the thickness of the bottom wall 13b made of stainless steel can be obtained. When a frequency selected by the transmitter 32 is set and an alternating current of that frequency is passed through the measuring coil 31, a magnetic field is induced in the measuring coil 31. The measurement coil 31 is brought close to the bottom wall 13 b as the wall portion of the case 11. Magnetic flux generated in the measuring coil 31 is applied to the outer surface of the bottom wall 13b at a right angle to generate an eddy current in the bottom wall 13b. At this time, since the frequency M is set so as to obtain a penetration depth N exceeding the thickness of the bottom wall 13b, a conductor is provided on the opposite side of the bottom wall 13b (on the bottom wall 13b in the case 11). If (electrolyte) is present, eddy current is also generated in this conductor.

  As shown in FIGS. 5 (a) and 6 (a), when the electrode assembly 12 is sufficiently impregnated with the electrolyte, the case 11 is opposite to the bottom wall 13b with the measuring coil 31 approached. On the bottom wall 13b that is the side, there is no electrolytic solution that is a conductor, and no electrolytic solution remains.

  That is, as shown in FIGS. 6A and 7, a slight gap T is defined between the upper surface of the bottom wall 13b and the outer surface of the electrode assembly 12 facing the bottom wall 13b. The void T is generated in the lithium ion battery in order to set a size relationship between the sizes of the positive electrode active material layer 21b, the negative electrode active material layer 24b, and the separator 27 in order to suppress lithium deposition. For this reason, the eddy current reaching the inside of the case 11 is limited in the depth at which the eddy current is generated due to the presence of the slight gap T.

  A magnetic field is generated by the generated eddy current, the magnetic flux enters the measurement coil 31, a current is induced in the measurement coil 31 (reaction current), and a current flows through the measurement coil 31. Then, the change in the current flowing through the measuring coil 31 is converted into impedance by the bridge circuit 33, and the impedance value is displayed on the display 34. Then, the impedance value detected during the impregnation inspection process is compared with a preset appropriate value. Since there is no electrolyte solution on the bottom wall 13b, the detected impedance value becomes an appropriate value, and it can be determined that the electrode assembly 12 is sufficiently impregnated with the electrolyte solution.

  On the other hand, as shown in FIGS. 5B and 6B, if the electrode assembly 12 is not sufficiently impregnated with the electrolyte, dot hatching in FIGS. 5B and 6B will occur. As shown, the electrolyte D remains (exists) on the bottom wall 13b of the case 11, the gap T is filled with the electrolyte D, and there is no gap T. For this reason, the eddy current that has reached the inside of the case 11 is generated to a deeper position due to the presence of the electrolytic solution D, that is, a deeper position than when there is no electrolytic solution.

  Therefore, as shown in FIG. 7, if the electrolyte remains, the current flowing through the measurement coil 31 is different from the case where there is no electrolyte (when the gap T is present), and the impedance value is also different. Therefore, the display 34 displays that the impedance value is not an appropriate value. Therefore, it can be determined from the impedance value that the electrode assembly 12 is not sufficiently impregnated with the electrolyte.

  Thereafter, an aging process of the secondary battery 10 is performed. When the aging process is completed, in the secondary battery 10, the sealing member 20 is removed from the liquid injection hole 14c, and the gas generated in the aging process is released from the liquid injection hole 14c to the outside of the case 11. After the step of releasing the gas, the liquid injection hole 14 c is sealed with another sealing member 20. Thereafter, the secondary battery 10 is self-discharged to complete the secondary battery 10.

Next, the case where the impregnation inspection process of the secondary battery provided with the wound electrode assembly as the electrode assembly is performed will be described.
As shown in FIG. 8, in the secondary battery 40 having the wound electrode assembly 42, the electrode assembly 42 was wound in a spiral shape with the positive electrode and the negative electrode insulated by a separator. Is. The case 41 of the secondary battery 40 includes a bottomed square cylindrical case main body 43 and a rectangular flat plate-shaped lid body 44 that closes an opening 43 a for inserting the electrode assembly 42 into the case main body 43. . Both the case main body 43 and the lid 44 are made of stainless steel. The case body 43 includes a rectangular plate-shaped bottom wall 43b, a first side wall 43c erected from a pair of first side edges (short side edges) of the bottom wall 43b, and another pair of second sides of the bottom wall 43b. And a second side wall 43d erected from the edge (long side edge).

  The electrode assembly 42 has an outer peripheral surface that is curved along the circumferential direction of the winding axis L. In the case 41 of the secondary battery 40, the peripheral surface of the electrode assembly 42 is in close contact with the inner surfaces of the bottom wall 43b and the second side walls 43d. A space S is defined in the case 41 by the rounded portion of the electrode assembly 42, the inner surface of the bottom wall 43b, and the inner surface of the second side wall 43d.

In the impregnation inspection process for the secondary battery 40 including the wound electrode assembly 42, first, the secondary battery 40 is tilted toward the second side wall 43d.
At this time, if the electrode assembly 42 is sufficiently impregnated with the electrolytic solution, the electrolytic solution does not remain (does not exist) in the space S, and only the space S exists. When the measurement coil 31 is brought closer to the second side wall 43d on the bottom wall 43b, the eddy current reaching the inside of the case 41 has a depth at which the eddy current is generated due to the presence of the space S. It is limited only to the side wall 43d. For this reason, when the impedance value obtained by the generated eddy current is compared with a preset appropriate value, the detected impedance value is an appropriate value. It can be determined that it is sufficiently impregnated.

  On the other hand, as shown in FIG. 8, if the electrode assembly 42 is not sufficiently impregnated with the electrolyte D, the electrolyte D accumulates in the space S. For this reason, the eddy current that has reached the inside of the case 41 is generated to a deeper position due to the remaining (presence) of the electrolytic solution D, that is, a deeper position than when there is no electrolytic solution. For this reason, when the impedance value obtained by the generated eddy current is compared with a preset appropriate value, the display 34 displays that the impedance value is not an appropriate value. Therefore, it can be determined from the impedance value that the electrode assembly 42 is not sufficiently impregnated with the electrolyte.

According to the above embodiment, the following effects can be obtained.
(1) When the secondary batteries 10 and 40 are manufactured, whether the electrode assemblies 12 and 42 are sufficiently impregnated with the electrolytic solution is determined in the impregnation inspection step after the impregnation step and before the aging step. I did it. That is, in the stacked secondary battery 10, it is determined whether or not the electrolytic solution is sufficiently impregnated using a change in eddy current that changes depending on the presence or absence of the gap T in the case 11. In the secondary battery 40, it is determined whether or not the electrolyte is sufficiently impregnated by using a change in eddy current that changes depending on the presence or absence of the space S in the case 41. Therefore, it is possible to determine whether the electrolyte assembly is sufficiently impregnated in the electrode assembly 12 or 42 regardless of whether the electrode assembly 12 or 42 is a wound type or a laminated type. Can be increased.

  (2) Also, the frequency of the alternating current that flows through the measuring coil 31 is set in accordance with the thickness and material of the bottom walls 13b and 43b of the cases 11 and 41. For this reason, even if the sizes and types of materials of the cases 11 and 41 are various, it can be determined whether or not the electrode assembly 12 or 42 is sufficiently impregnated with the electrolyte, and the versatility of the impregnation inspection process can be improved. Can do.

  (3) In the impregnation inspection step, the measurement coil 31 is brought close to the outer surfaces of the bottom walls 13b and 43b in the cases 11 and 41 to determine whether or not the electrode assemblies 12 and 42 are sufficiently impregnated with the electrolyte. . If the electrode assembly 12 or 42 is not sufficiently impregnated with the electrolyte, the electrolyte will accumulate on the bottom walls 13b and 43b of the cases 11 and 41 due to its own weight. For this reason, it can be determined whether or not the electrode assemblies 12 and 42 are sufficiently impregnated from the presence or absence of the electrolyte accumulated in the bottom walls 13b and 43b.

  (4) The impregnation inspection step is performed after the electrolytic solution impregnation step and before the aging step. For this reason, if it can be determined that the electrolyte solution is not sufficiently impregnated in the electrode assemblies 12, 42, the time for additional impregnation of the electrolyte solution can be set before the aging step.

In addition, you may change the said embodiment as follows.
In the embodiment, the measurement coil 31 is brought close to the bottom walls 13b and 43b of the cases 11 and 41 to determine whether or not the electrolyte is impregnated. In addition to this, the impregnation is also performed by another method. It is also possible to perform an inspection.

As shown in FIG. 9, the measurement coil 31 may be scanned while approaching a pair of second side walls 13 d and 43 d as wall portions, and the inside of the electrode assemblies 12 and 42 may be an inspection target.
At this time, as shown in the table of FIG. 10, when the electrode assemblies 12 and 42 are sufficiently impregnated with the electrolyte, the positive electrode active material layer 21 b and the negative electrode active material adjacent to each other in the stacking direction of the electrode assemblies 12 and 42. The pores in the material layer 24b and the separator 27 are filled with the electrolytic solution, and there are no voids.

  In this state, as shown in FIG. 9, the measurement coil 31 is brought close to the second side walls 13d and 43d, eddy currents are generated in the second side walls 13d and 43d, and the second side walls 13d and 43d are approached. And scanning. Since the internal state of the cases 11 and 41 is uniform, the current flowing through the measurement coil 31 does not change.

  As a result, as shown in FIG. 10, there is no change in the detected impedance value, and the electrolyte is sufficiently impregnated in the stacking direction of the electrode assemblies 12 and 42 by detecting the impedance. Is determined.

  On the other hand, if the electrode assemblies 12 and 42 are not sufficiently impregnated with the electrolyte solution, the positive electrode active material layer 21b, the negative electrode active material layer 24b, and the pores in the separator 27 are not impregnated with the electrolyte solution. There are parts (voids). In this state, the measurement coil 31 is brought close to the second side walls 13d and 43d, eddy currents are generated on the second side walls 13d and 43d, and the second side walls 13d and 43d are scanned. As a result, the current flowing through the measurement coil 31 changes in a portion not impregnated with the electrolytic solution. Therefore, it is determined that the electrolytic solution is not sufficiently impregnated in the electrode assemblies 12 and 42 by detecting that the impedance value changes.

  Therefore, whether or not the electrolyte is sufficiently impregnated can be determined also in the stacking direction of the electrode assemblies 12 and 42. Since the impregnation test is performed from both the second side walls 13d and 43d, it can be more accurately determined whether or not the electrolytic solution is sufficiently impregnated to the center in the stacking direction of the electrode assemblies 12 and 42.

The impregnation inspection may be performed from one of the second side walls 13d and 43d.
O You may perform the test | inspection process which test | inspects whether the electrolyte solution has leaked from the electrode assemblies 12 and 42 using the test | inspection apparatus 30 used at the impregnation test | inspection process.

For example, the secondary batteries 10 and 40 may receive vibrations or the like, and the electrolyte solution may leak from the electrode assemblies 12 and 42.
In this case, as shown in FIG. 11, the space between the inner surfaces of the cases 11 and 41 and the outer surfaces of the electrode assemblies 12 and 42 is filled with the electrolytic solution, and there is no gap T or space S. In this state, for example, the measurement coil 31 is brought close to the bottom walls 13b and 43b of the cases 11 and 41, and eddy currents are generated on the bottom walls 13b and 43b.

  Then, the eddy current is generated in a deeper position due to the presence of the electrolytic solution, that is, a deeper position than in the case where there is no leakage of the electrolytic solution. Therefore, the current flowing through the measurement coil 31 is different from the case where the electrolyte does not leak, and the impedance value is also different. Therefore, the display 34 displays that the impedance value is not an appropriate value. Therefore, it is determined that the electrolyte is leaking from the electrode assembly 12 based on the impedance value.

  On the other hand, if the electrolyte does not leak from the electrode assemblies 12 and 42 and the electrolyte is sufficiently impregnated in the electrode assemblies 12 and 42, the inner surfaces of the cases 11 and 41 and the electrode assemblies 12 and 42 There are slight gaps T and spaces S between the outer surface and the electrolyte solution. Therefore, when the inspection apparatus 30 performs the inspection, the depth of the eddy current that has reached the inside of the cases 11 and 41 is limited due to the presence of the gap T and the space S. Therefore, unlike the case where the electrolyte is leaking, the current flowing through the measuring coil 31 has an appropriate impedance value, and the display 34 displays that the impedance value is an appropriate value. For this reason, it is determined that the electrolyte does not leak from the electrode assemblies 12 and 42 based on the impedance value.

Therefore, even in the inspection of the secondary batteries 10 and 40, it is possible to determine whether or not the electrolyte is leaking regardless of the form of the electrode assemblies 12 and 42.
In the inspection apparatus 30, the type, shape, and guidance method of the measurement coil 31 may be changed as appropriate.

  In the impregnation inspection step and the inspection step, the measurement coil 31 may be brought close to the outer surfaces of the first side walls 13c and 43c of the cases 11 and 41 as wall portions. At this time, the secondary batteries 10 and 40 may be tilted so that the first side walls 13c and 43c and the second side walls 13d and 43d of the secondary batteries 10 and 40 are at the bottom, or the first side walls 13c and 43c On the two side walls 13d and 43d, the measuring coil 31 is moved closer to the bottom walls 13b and 43b.

  In the embodiment, the change in the current flowing through the measurement coil 31 is detected as the change in the impedance value, but the present invention is not limited to this. For example, a change in the current flowing through the measurement coil 31 may be detected as a change in voltage.

  In the embodiment, whether or not the electrolyte is sufficiently impregnated by comparing the impedance value detected when the measurement coil 31 is brought close to the bottom walls 13b and 43b with a preset appropriate value. However, the present invention is not limited to this. For example, when the inspection apparatus 30 includes a plurality of measurement coils 31, the impedance values detected by the plurality of measurement coils 31 are made close to a plurality of measurement coils 31, for example, the bottom walls 13 b and 43 b. Compare Then, it may be determined whether or not the electrolytic solution is sufficiently impregnated based on a plurality of detected impedance values.

  In the embodiment, the impedance value is displayed on the display 34, but the present invention is not limited to this. For example, in the production facility for the secondary batteries 10 and 40, if the electrode assemblies 12 and 42 are not sufficiently impregnated with the electrolyte, an exclusion facility for removing the secondary batteries 10 and 40 is provided. Further, the inspection device 30 converts the measured impedance and current values into signals and outputs the signals to the exclusion facility. When it is determined that the electrode assemblies 12 and 42 are not sufficiently impregnated with the electrolyte based on the current and impedance values, a signal to that effect is output to the exclusion facility, and the electrode assemblies 12 and 42 are notified. The secondary batteries 10 and 40 that are not impregnated with 10 parts of the electrolytic solution may be excluded by an exclusion facility.

  In the embodiment, the positive electrode 21 has the positive electrode active material layer 21b on both sides of the positive electrode metal foil 21a, but may have the positive electrode active material layer 21b only on one side of the positive electrode metal foil 21a. Similarly, the negative electrode 24 has the negative electrode active material layer 24b on both sides of the negative electrode metal foil 24a, but may have the negative electrode active material layer 24b only on one side of the negative electrode metal foil 24a.

The secondary batteries 10 and 40 are lithium ion secondary batteries, but are not limited thereto, and may be other secondary batteries such as nickel metal hydride. In short, any material having an electrolyte solution may be used.
Next, a technical idea that can be grasped from the above embodiment and another example will be additionally described.

  (A) The power storage device is a secondary battery.

  D ... electrolyte, M ... frequency, N ... penetration depth, 10,40 ... secondary battery as power storage device, 11,41 ... case, 12,42 ... electrode assembly, 13b, 43b ... bottom as wall A wall, 13d, a second side wall as a wall, 21 a positive electrode, 24 a negative electrode, 31 a measuring coil.

Claims (5)

An electrode assembly in which electrodes of different poles are alternately stacked in a state where the electrodes are insulated from each other, and a method of manufacturing a power storage device including an electrolytic solution in a metal case,
An injection step of injecting the electrolytic solution into the case;
An impregnation step of impregnating the electrode assembly with the electrolytic solution;
An impregnation inspection step that is performed after the impregnation step and before the aging step, and determines whether or not the electrode assembly is sufficiently impregnated in the electrode assembly,
The impregnation inspection process includes
An alternating current is passed through the measuring coil in a state where the measuring coil is brought close to the wall of the case, and an eddy current is generated in the wall of the case. The frequency of the alternating current is set according to the thickness of the case wall and the material of the case so as to be deeper than the thickness of the case wall close to the coil, and the inner surface of the case wall A method for manufacturing a power storage device that determines an impregnation state of the electrolyte solution in the electrode assembly based on a change in the eddy current that changes depending on the presence or absence of a gap or space existing between the outer surface of the electrode assembly.   The measurement coil is connected to a bridge circuit that converts a change in current induced in the measurement coil in response to the eddy current into a change in impedance;
  The method for manufacturing a power storage device according to claim 1, wherein in the impregnation inspection step, an impregnation state of the electrode assembly with the electrolytic solution is determined based on an impedance value obtained by the generated eddy current. The case has a bottom wall as the wall portion, a manufacturing method of a power storage device according to claim 1 or claim 2 wherein the penetration depth is to set the frequency to be deeper than the thickness of the bottom wall . The case has side walls opposed to both ends in the stacking direction of the electrode assembly, and the measurement coil is scanned along the side wall as the wall portion, and the electrolyte solution is stacked in the stacking direction of the electrode assembly. The method for manufacturing a power storage device according to claim 1, wherein it is determined whether or not the material is impregnated. An electrode assembly in which electrodes of different poles are alternately stacked in a state where the electrodes are insulated from each other, and a method for inspecting a power storage device including an electrolyte in a case,
Having an inspection step of determining whether or not the electrolyte is leaking from the electrode assembly;
The inspection process includes
An alternating current is passed through the measuring coil in a state where the measuring coil is brought close to the wall of the case, and an eddy current is generated in the wall of the case. A method for inspecting a power storage device that determines whether or not the electrolytic solution is leaking from the electrode assembly by setting the frequency of the alternating current so as to be deeper than the thickness of the wall portion of the case where the coil is approached. .