JP6221856B2 - Power storage device and method for manufacturing power storage device - Google Patents

Description

  The present invention relates to a power storage device in which an electrode assembly and a thickness adjusting member are accommodated in a case, and a method for manufacturing the power storage device.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. The secondary battery includes, for example, an electrode assembly in which a positive electrode and a negative electrode each including an active material layer are stacked with a separator interposed therebetween, and a case that houses the electrode assembly.

  When manufacturing the secondary battery, if the length in the stacking direction of the electrode assembly is shorter than a predetermined range due to the manufacturing tolerance of each electrode or separator, the electrode assembly is stored in the case in the case of the electrode assembly. The gap between the electrode assembly and the inner surface of the case in the stacking direction will be too large. If the gap becomes large in this way, the electrode assembly moves in the stacking direction within the case, which is not preferable.

  Therefore, in the secondary battery described in Patent Document 1, such a gap is reduced by inserting a thickness adjusting member into the gap between the electrode assembly and the inner surface of the case in the stacking direction of the electrode assembly. Yes.

JP 2008-108457 A

  By the way, in the secondary battery described in Patent Document 1, the thickness adjusting member is located in the gap between the electrode assembly and the inner surface of the case in the stacking direction of the electrode assembly. If the heat transfer is inhibited by the thickness adjusting member, the heat of the electrode assembly may not be properly transmitted to the case.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to appropriately transmit heat of the electrode assembly to the case when the thickness adjusting member is housed in the case together with the electrode assembly. An object of the present invention is to provide a power storage device and a method for manufacturing the power storage device.

In the following, means for achieving the above object and its effects are described.
A power storage device that solves the above problems includes an electrode assembly in which a positive electrode and a negative electrode including an active material layer are stacked with a separator interposed therebetween, and a case that houses the electrode assembly. Yes. The electrode assembly includes a first electrode assembly and a second electrode assembly in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, and in the stacking direction of the electrode assembly, the first electrode assembly A thickness adjusting member for adjusting a gap between the electrode assembly and the case is located between the solid body and the second electrode assembly and in the center of the electrode assembly.

  According to the said structure, since the thickness adjustment member is located in the center of the lamination direction of an electrode assembly, heat transfer is accelerated | stimulated from a 1st electrode assembly and a 2nd electrode assembly to a case, respectively. Therefore, the heat of the electrode assembly can be appropriately transferred to the case.

The thickness adjusting member is preferably composed of, for example, a plurality of thickness adjusting films.
According to the above configuration, since the plurality of thickness adjusting films are all located at the center of the electrode assembly, the thickness is compared with the case where the plurality of thickness adjusting films are arranged at different positions in the stacking direction of the electrode assembly. The inhibition of heat transfer by the adjustment member can be suppressed. Therefore, the heat of the electrode assembly can be more appropriately transmitted to the case.

  As a preferred example of the first electrode assembly and the second electrode assembly, the difference in the number of positive electrodes constituting each of them is one or less, and the positive electrode and the negative electrode constituting each are combined. The difference in the number of sheets is 2 or less.

In the above power storage device, a preferable example of the power storage device is a secondary battery.
A method for manufacturing a power storage device that solves the above problem is a method for manufacturing a power storage device including an electrode assembly in which a positive electrode and a negative electrode including an active material layer are stacked with a separator interposed therebetween. In this method of manufacturing a power storage device, the electrode assembly includes a first electrode assembly and a second electrode assembly that are stacked with a positive electrode and a negative electrode sandwiched between separators. A plurality of three-dimensional and second electrode assemblies are manufactured, and the lengths of the manufactured first electrode assemblies and second electrode assemblies in the stacking direction are respectively measured, and a plurality of first electrode assemblies and second electrode assemblies are measured. A first electrode assembly and a second electrode assembly that have a total length in the stacking direction within a predetermined range are selected from the three-dimensional objects. Then, by positioning the thickness adjusting member between the first electrode assembly and the second electrode assembly in the stacking direction and stacking the first electrode assembly and the second electrode assembly, the center in the stacking direction is obtained. One electrode assembly having a thickness adjusting member is manufactured, and the electrode assembly is accommodated in a case.

  According to the said structure, since the thickness adjustment member is located in the center of the lamination direction of an electrode assembly, heat transfer is accelerated | stimulated from a 1st electrode assembly and a 2nd electrode assembly to a case, respectively. Therefore, the heat of the electrode assembly can be appropriately transferred to the case.

  In addition, the length in the stacking direction may be different for each manufactured electrode assembly due to manufacturing tolerance of each electrode or separator. In this case, even if the number of electrodes and separators is the same as the set number, the length in the stacking direction of the electrode assemblies varies among the electrode assemblies. Then, a thickness adjusting member corresponding to such variation is selected, and the selected thickness adjusting member is accommodated in the case together with the electrode assembly, so that the gap between the electrode assembly and the case is adjusted by the thickness adjusting member. Is done.

  According to the above configuration, the electrode assembly is formed by laminating the first electrode assembly and the second electrode assembly, and the total length in the stacking direction is determined as the first electrode assembly and the second electrode assembly. Those within the predetermined range are selected. For this reason, in the electrode assembly manufactured by laminating the first electrode assembly and the second electrode assembly, the variation among the electrode assemblies can be reduced.

  Here, when the thickness adjusting member is positioned on the electrode assembly, the thickness adjusting member having a different thickness is selected so that the thickness adjusting member having an appropriate thickness can be selected in accordance with the variation in the length of the electrode assembly in the stacking direction. It is necessary to prepare. However, even in such a case, the range of the thickness adjusting member to be prepared can be reduced by reducing the variation among the electrode assemblies as described above. Therefore, it is possible to improve workability and reduce costs related to the thickness adjusting member.

  According to the present invention, when the thickness adjusting member is housed in the case together with the electrode assembly, the heat of the electrode assembly can be appropriately transmitted to the case.

The disassembled perspective view of the secondary battery in this embodiment. The disassembled perspective view which shows the component of a 1st electrode assembly and a 2nd electrode assembly. The disassembled perspective view which shows the component of an electrode assembly. Sectional drawing of a secondary battery. The disassembled perspective view which shows the component of the electrode assembly in another embodiment. Sectional drawing of the secondary battery in another embodiment.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, in a secondary battery 10 as a power storage device, an electrode assembly 12 is accommodated in a case 11. The electrode assembly 12 includes a first electrode assembly 12a and a second electrode assembly 12b. The case 11 also contains an electrolyte solution together with the electrode assembly 12. The case 11 includes a bottomed cylindrical case body 13 and a flat lid 14 that closes an opening for inserting the electrode assembly 12 into the case body 13. Both the case main body 13 and the lid body 14 are made of metal (for example, made of stainless steel or aluminum). In addition, the secondary battery 10 of this embodiment is a rectangular battery whose appearance is a rectangular shape because the case body 13 has a bottomed rectangular tube shape and the lid body 14 has a rectangular flat plate shape. Moreover, the secondary battery 10 of this embodiment is a lithium ion battery.

  As shown in FIG. 2, the first electrode assembly 12a and the second electrode assembly 12b constituting the electrode assembly 12 are alternately arranged with a plurality of positive electrodes 21 and negative electrodes 25 sandwiching a separator 29 therebetween. It is laminated and configured. Each of the electrodes 21 and 25 and the separator 29 has a rectangular shape. The positive electrode 21 has a shape that is slightly smaller than the negative electrode 25. Specifically, the length of each side of the positive electrode 21 is set shorter than the length of each side of the negative electrode 25. The separator 29 has a shape that is slightly larger than the negative electrode 25. Specifically, the length of each side of the separator 29 is set longer than the length of each side of the negative electrode 25.

  The positive electrode 21 includes a rectangular positive metal foil (for example, aluminum foil) 22 and a positive electrode active material layer 23 having a positive electrode active material on both surfaces of the positive electrode metal foil 22. The positive electrode active material layer 23 is located in the entire region other than a part of the positive electrode 21 along the one side 21 c of the positive electrode 21. Further, the positive electrode 21 has a positive electrode tab 24 protruding from a part of one side 21 c of the positive electrode 21.

  The negative electrode 25 includes a rectangular negative metal foil (for example, copper foil) 26 and a negative electrode active material layer 27 having a negative electrode active material on both surfaces of the negative electrode metal foil 26. The negative electrode metal foil 26 has a shape that is slightly larger than the positive electrode metal foil 22. The negative electrode active material layer 27 is located in the entire region of the negative electrode 25 other than a part of the region along the one side 25 c of the negative electrode 25, and is located in a region larger than the positive electrode active material layer 23. Further, the negative electrode 25 has a negative electrode tab 28 protruding from a part of one side 25 c of the negative electrode 25.

The electrodes 21 and 25 are stacked so that the same polarities of the tabs 24 and 28 are arranged in a row in the stacking direction, while different polarities do not overlap in the stacking direction.
As shown in FIG. 3, the first electrode assembly 12 a and the second electrode assembly 12 b have the same number of positive electrodes 21 and negative electrodes 25. In detail, in this embodiment, the positive electrode 21 of the 1st electrode assembly 12a and the positive electrode 21 of the 2nd electrode assembly 12b are the same number. That is, the sum of the number of positive electrodes 21 of the first electrode assembly 12a and the number of positive electrodes 21 of the second electrode assembly 12b is an even number. Further, the negative electrode 25 of the first electrode assembly 12a and the negative electrode 25 of the second electrode assembly 12b are the same number. Further, in the first electrode assembly 12a and the second electrode assembly 12b, the number of separators 29 is the same as the number of positive electrodes 21 and negative electrodes 25.

  The number of electrodes 21 and 25 and separators 29 constituting the first electrode assembly 12a and the second electrode assembly 12b is such that the first electrode assembly 12a and the second electrode assembly 12b are stacked. When the solid body 12 is formed, the length S1 ′ of the electrode assembly 12 in the stacking direction is set to be slightly smaller than the length S2 of the inner dimension of the case 11. This is because when the first electrode assembly 12a and the second electrode assembly 12b are stacked, the electrode assemblies 12 and 25 and the separator 29 even if the actual thicknesses have the maximum manufacturing tolerances. This is because the number of the electrodes 21 and 25 and the separators 29 constituting the first electrode assembly 12a and the second electrode assembly 12b is set so as to fit in the case 11.

  Here, a variation in thickness may occur between the electrodes 21 and 25 due to, for example, application of an active material to the metal foils 22 and 26 of the electrodes 21 and 25. If the thicknesses of the electrodes 21 and 25 vary in this way, the first electrode assembly 12a and the second electrode assembly 12b can be formed in the first electrode assembly 12a and the second electrode assembly 12b even if the number of the electrodes 21 and 25 and the separator 29 is set to the set number. Variations occur in the lengths S3 and S4 in the stacking direction for each electrode assembly 12a and each second electrode assembly 12b. If these lengths S3 and S4 are small, when the electrode assembly 12 is formed by stacking the first electrode assembly 12a and the second electrode assembly 12b, the length S3 and the length S4 The total length S1 ′ of the electrode assembly 12 in the stacking direction is shorter than the expected length. For this reason, when the electrode assembly 12 is inserted into the case 11, a gap between the electrode assembly 12 and the inner surface of the case 11 in the stacking direction of the electrode assembly 12 is increased.

  Therefore, in the present embodiment, the thickness adjusting member 30 is disposed between the first electrode assembly 12a and the second electrode assembly 12b. The thickness adjusting member 30 is made of a resin such as polypropylene, and is composed of a rectangular thickness adjusting film 30a. The thickness adjusting film 30 a is slightly larger than the positive electrode 21 and has the same size as the negative electrode 25. In the present embodiment, the number of thickness adjusting films 30a as the thickness adjusting member 30 is set as follows. That is, the length S5 in the stacking direction of the plurality of thickness adjusting films 30a is the sum of the length S3 in the stacking direction of the first electrode assembly 12a and the length S4 in the stacking direction of the second electrode assembly 12b. And the number of laminated layers of the thickness adjusting film 30a is set so as to be the difference between the inner dimension length S2 of the case 11. Thereby, in the electrode assembly 12 configured by sandwiching the thickness adjusting member 30 between the first electrode assembly 12a and the second electrode assembly 12b, the total of the length S3, the length S4, and the length S5. The length S1 of the electrode assembly 12 in the stacking direction, which is the length, is approximately the same as the length S2 of the inner dimension of the case 11.

  As shown in FIG. 4, the outermost layers of the first electrode assembly 12a and the second electrode assembly 12b are the negative electrodes 25, respectively. For this reason, the thickness adjusting member 30 is sandwiched from both sides of the electrode assembly 12 in the stacking direction by the negative electrode 25 positioned as the outermost layer of the first electrode assembly 12a and the second electrode assembly 12b. An insulating member 55 is disposed on the inner surface of the case body 13 of the case 11. Therefore, in a state where the electrode assembly 12 is inserted into the case 11, the insulating member 55 is interposed between both end surfaces of the electrode assembly 12 in the stacking direction and the inner surface of the case body 13.

  Note that, as described above, in the present embodiment, the first electrode assembly 12a and the second electrode assembly 12b have the same number of positive electrodes 21 and negative electrodes 25. For this reason, in the electrode assembly 12, the space between the first electrode assembly 12a and the second electrode assembly 12b in the stacking direction is the center of the electrode assembly 12 in the stacking direction. That is, in the state where the thickness adjusting member 30 is disposed between the first electrode assembly 12a and the second electrode assembly 12b, the thickness adjusting member 30 is located at the center in the stacking direction of the electrode assembly 12. .

  As shown in FIG. 1, in the secondary battery 10, a positive electrode tab 24 and a negative electrode tab 28 are formed from an upper end 12 c that is one of four ends positioned in a direction orthogonal to the stacking direction of the electrode assembly 12. The first electrode assembly 12a and the second electrode assembly 12b are stacked so that each protrudes from each other. Each positive electrode tab 24 is bent in a state of being collected within a range from one end to the other end in the stacking direction of the electrode assembly 12. That is, the positive electrode tab 24 of the first electrode assembly 12a and the positive electrode tab 24 of the second electrode assembly 12b are gathered together and bent. And each positive electrode tab 24 is electrically connected mutually by welding the location where each positive electrode tab 24 has overlapped. Similarly, the negative electrode tab 28 is bent in a collected state. That is, the negative electrode tab 28 of the first electrode assembly 12a and the negative electrode tab 28 of the second electrode assembly 12b are gathered together and bent. The negative electrode tabs 28 are electrically connected to each other by welding the portions where the negative electrode tabs 28 overlap.

  The secondary battery 10 includes a positive electrode terminal 15 electrically connected to each positive electrode tab 24 and a negative electrode terminal 16 electrically connected to each negative electrode tab 28. A part of each of the terminals 15 and 16 is exposed to the outside of the case 11 through a through hole formed in the lid body 14.

  A plurality of (six in this embodiment) fixing tapes 45 are attached to the electrode assembly 12. Specifically, the electrode assembly 12 is fixed by affixing the fixing tape 45 across both end surfaces of the electrode assembly 12 in the stacking direction. In this way, a plurality of fixing tapes 45 are affixed to the electrode assembly 12, whereby the first electrode assembly 12a, the second electrode assembly 12b, and the thickness adjusting member 30 are fixed.

Next, the manufacturing method of the secondary battery 10 will be described together with the operation.
First, a plurality of first electrode assemblies 12a and second electrode assemblies 12b are manufactured by laminating a predetermined number of positive electrodes 21, negative electrodes 25, and separators 29, respectively. The lengths S3 and S4 of the manufactured first electrode assembly 12a and second electrode assembly 12b in the stacking direction are measured. Then, based on the measured lengths S3 and S4 of the first electrode assembly 12a and the second electrode assembly 12b in the stacking direction, the number of the thickness adjusting films 30a as the thickness adjusting members 30 is determined.

  As described above, the lengths S3 and S4 in the stacking direction may be different for each manufactured first electrode assembly 12a and second electrode assembly 12b due to manufacturing tolerances of the electrodes 21 and 25 and the separator 29. . In the present embodiment, among the plurality of first electrode assemblies 12a and second electrode assemblies 12b manufactured, the sum of the length S3 and the length S4 is equal to the length S2 of the inner dimension of the case 11. A combination of the first electrode assembly 12a and the second electrode assembly 12b that are within a predetermined range with a small difference is selected. That is, the first electrode assembly 12a and the second electrode assembly 12b can compensate for the excess and deficiency of the lengths S3 and S4 with respect to the assumed length, and the first electrode assembly having appropriate lengths S3 and S4. The solid 12a and the second electrode assembly 12b are selected.

  By selecting the first electrode assembly 12a and the second electrode assembly 12b in this manner, the total length (length) of the length S3 of the first electrode assembly 12a and the length S4 of the second electrode assembly 12b is selected. S1 ′) has a small variation for each electrode assembly 12.

  Then, the electrode assembly 12 is manufactured by disposing the thickness adjusting member 30 between the selected first electrode assembly 12a and the second electrode assembly 12b. The number of the thickness adjusting films 30a arranged on the electrode assembly 12 as the thickness adjusting member 30 is the sum of the length S3 of the first electrode assembly 12a and the length S4 of the second electrode assembly 12b and the case 11. It is selected according to the difference with the length S2. Thus, the electrode assembly 12 in which the thickness adjusting member 30 is arranged has a small variation in the length S1 in the stacking direction for each electrode assembly 12.

  Next, a load is applied to the manufactured electrode assembly 12 from the end surface in the stacking direction of the electrode assembly 12 in the stacking direction. Then, in a state where a load is applied to the electrode assembly 12, a plurality of fixing tapes 45 are attached to both end surfaces in the stacking direction of the electrode assembly 12, and the electrode assembly 12 is held by these fixing tapes 45. It is assumed that the stacking deviation of the assembly 12a, the second electrode assembly 12b, and the thickness adjusting member 30 is suppressed.

  In the electrode assembly 12 fixed by the fixing tape 45, the positive electrode tabs 24 of the first electrode assembly 12a and the second electrode assembly 12b are collected in the stacking direction in the electrode assembly 12 and welded. The negative electrode tabs 28 of the first electrode assembly 12a and the second electrode assembly 12b are collected in the stacking direction in the electrode assembly 12 and welded. Each positive electrode tab 24 and the positive electrode terminal 15 are electrically connected, and each negative electrode tab 28 and the negative electrode terminal 16 are electrically connected.

  Thereafter, the electrode assembly 12 is inserted into the case body 13 from the opening of the case body 13 of the case 11, and the opening of the case body 13 is closed with the lid body 14, whereby the secondary battery 10 is manufactured. As described above, since the electrode assembly 12 is manufactured such that the difference in the length S1 in the stacking direction with respect to the length S2 of the inner dimension of the case 11 is small, the electrode assembly 12 is accommodated in the case 11. In this state, the gap between the electrode assembly 12 and the case 11 (case body 13) is small in the stacking direction of the electrode assembly 12.

  In addition, as described above, the first electrode assembly 12a and the second electrode assembly 12b have the same number of positive electrodes 21 constituting each, and the positive electrode 21 and the negative electrode 25 constituting each of the first electrode assembly 12a and the second electrode assembly 12b. The combined number is the same. Therefore, the thickness of the manufactured secondary battery 10 is adjusted between the first electrode assembly 12a and the second electrode assembly 12b and in the center of the electrode assembly 12 in the stacking direction of the electrode assemblies 12. The member 30 is located. That is, in the electrode assembly 12, between the end surface in the stacking direction of the first electrode assembly 12a and the inner surface of the case body 13 facing the end surface, or in the stacking direction of the second electrode assembly 12b and the end surface. The thickness adjusting member 30 is not positioned between the facing inner surface of the case body 13. Therefore, the heat of the electrode assembly 12 is transmitted from the end surface in the stacking direction of the first electrode assembly 12a to the inner surface of the case body 13 facing the end surface, and from the end surface in the stacking direction of the second electrode assembly 12b. It is transmitted to the inner surface of the case body 13 facing the end surface.

As described above, according to the present embodiment, the following effects can be obtained.
(1) Since the thickness adjusting member 30 is located at the center of the electrode assembly 12 in the stacking direction, heat transfer is promoted from the first electrode assembly 12a and the second electrode assembly 12b to the case 11, respectively. . Therefore, the heat of the electrode assembly 12 can be appropriately transferred to the case 11.

(2) Since the heat of the electrode assembly 12 can be transmitted to the case 11, as a result, the heat can be appropriately dissipated outside the case 11.
(3) In order to position all the plurality of thickness adjusting films 30a in the center of the electrode assembly 12, compared to the case where the plurality of thickness adjusting films 30a are arranged at different positions in the stacking direction of the electrode assembly 12, Inhibition of heat transfer by the thickness adjusting member 30 can be suppressed. Therefore, the heat of the electrode assembly 12 can be more appropriately transmitted to the case 11.

  (4) The first electrode assembly 12a and the second electrode assembly 12b are selected such that the sum of the lengths S3 and S4 in the stacking direction is within a predetermined range. For this reason, in the electrode assembly 12 manufactured by stacking the first electrode assembly 12a and the second electrode assembly 12b, variation in the length S1 ′ of the electrode assembly 12 for each electrode assembly 12 is reduced. be able to. Further, in the case where a plurality of thickness adjusting films 30a are positioned on the electrode assembly 12 as the thickness adjusting member 30 as in the present embodiment, an appropriate number of sheets is determined according to variations in the length S1 ′ of the electrode assembly 12. It is necessary to prepare a certain number of thickness adjusting films 30a so that the thickness adjusting film 30a can be selected. However, even in such a case, the number of the thickness adjusting films 30a to be prepared can be reduced by reducing the variation in the length S1 'for each electrode assembly 12 as described above. Therefore, it is possible to improve workability and reduce costs related to the thickness adjusting member 30.

  (5) The number of positive electrodes 21 constituting each of the first electrode assembly 12a and the second electrode assembly 12b is the same, and the total number of the positive electrodes 21 and the negative electrodes 25 constituting each of them. Are the same. That is, in the first electrode assembly 12a and the second electrode assembly 12b, the difference in the number of positive electrodes 21 constituting each is one or less, and the positive electrode 21 and the negative electrode 25 constituting each are combined. The number of the positive electrode 21 and the negative electrode 25 to be configured is set within a range where the difference in the number of sheets is two or less. For this reason, in the electrode assembly 12 in which the thickness adjusting member 30 is disposed between the first electrode assembly 12a and the second electrode assembly 12b, the thickness adjusting member 30 is positioned at the center in the stacking direction. . Of the both end surfaces of the electrode assembly 12 in the stacking direction, the length in the stacking direction from one end surface (the end surface in the stacking direction of the first electrode assembly 12a) to the thickness adjusting member 30 and the other end surface (second The deviation in size is reduced by the length in the stacking direction from the end surface of the electrode assembly 12b in the stacking direction) to the thickness adjusting member 30. Therefore, the heat of the electrode assembly 12 transmitted from the both end surfaces of the electrode assembly 12 in the stacking direction to the case 11 can be small in size deviation.

  (6) The electrode assembly 12 and the thickness adjusting member 30 are integrally held by the fixing tape 45. For this reason, the electrode assembly 12 and the thickness adjusting member 30 can be inserted into the case 11 in an integrated state, compared with the case where the electrode assembly 12 and the thickness adjusting member 30 are separately inserted into the case 11. Thus, the insertion work into the case 11 can be easily performed.

In addition, you may change the said embodiment as follows.
(Circle) the sticking position and the number of sticking of the fixed tape 45 can be changed suitably.
○ The manufactured first electrode assembly 12a and second electrode assembly 12b are individually fixed by the fixing tape 45, and the first electrode assembly 12a and the second electrode assembly 12b in a state of being fixed individually The thickness adjusting member 30 may be disposed therebetween, and the first electrode assembly 12a, the second electrode assembly 12b, and the thickness adjusting member 30 may be fixed by the fixing tape 45.

  O Sticking of the fixing tape 45 to the electrode assembly 12 may be omitted. According to such a form, the effect similar to effect (1)-(5) which can be acquired by the said embodiment can be acquired.

  Depending on the dimensions of the case 11, the electrode assembly 12 having the odd number of positive electrodes 21 may be accommodated. In such a form, the number of the positive electrode 21 and the negative electrode 25 which are comprised by the 1st electrode assembly 12a and the 2nd electrode assembly 12b comes to differ. For example, in the embodiment shown in FIGS. 5 and 6, the number of the positive electrodes 21 of the first electrode assembly 12a is one less than the number of the positive electrodes 21 of the second electrode assembly 12b, and the first electrode assembly 12a The number of the negative electrodes 25 is one less than the number of the negative electrodes 25 of the second electrode assembly 12b. 5 and FIG. 6, the number of separators 29 varies with the difference in the number of positive electrodes 21 and negative electrodes 25 between the first electrode assembly 12a and the second electrode assembly 12b. In this embodiment, the number of the separators 29 in the first electrode assembly 12a is two fewer than the separators 29 in the second electrode assembly 12b. And in the electrode assembly 12 of this form, between the 1st electrode assembly 12a and the 2nd electrode assembly 12b in a lamination direction becomes the center in the lamination direction of the electrode assembly 12. FIG. That is, in the state where the thickness adjusting member 30 is disposed between the first electrode assembly 12a and the second electrode assembly 12b, the thickness adjusting member 30 is located at the center in the stacking direction of the electrode assembly 12. . Even in such a form, the same effects as the effects (1) to (6) that can be obtained in the above embodiment can be obtained.

The thickness adjusting film 30a may be a film having a constant thickness or a film having a different thickness.
The thickness adjusting member 30 may be a single thickness adjusting member instead of the plurality of thickness adjusting films 30a. In this case, a plurality of thickness adjusting members having different thicknesses are prepared. Then, a thickness adjusting member having an appropriate thickness is selected according to the lengths S3 and S4 of the manufactured first electrode assembly 12a and second electrode assembly 12b, and the selected one thickness adjusting member is the first. It arrange | positions between the electrode assembly 12a and the 2nd electrode assembly 12b. According to such a form, the effects (1) to (3), (5), and (6) that can be obtained in the above embodiment and the following effects can be obtained.

  (7) The first electrode assembly 12a and the second electrode assembly 12b are selected such that the sum of the lengths S3 and S4 in the stacking direction is within a predetermined range. For this reason, in the electrode assembly 12 manufactured by stacking the first electrode assembly 12a and the second electrode assembly 12b, variation in the length S1 ′ of the electrode assembly 12 for each electrode assembly 12 is reduced. be able to. Further, when one member is positioned on the electrode assembly 12 as the thickness adjusting member 30 as in the present embodiment, a thickness adjusting member having an appropriate thickness is selected according to variations in the length S1 ′ of the electrode assembly 12 In order to be able to do so, it is necessary to prepare thickness adjusting members having different thicknesses. However, even in such a case, the variation in the length S1 'for each electrode assembly 12 is reduced as described above, so that the thickness range of the prepared thickness adjusting member can be reduced. Therefore, it is possible to improve workability and reduce costs related to the thickness adjusting member.

The thickness adjusting member 30 (thickness adjusting film 30 a) may be larger than the negative electrode 25.
The negative electrode 25 and the separator 29 may be the same size.

The positive electrode 21 and the negative electrode 25 may be the same size.
As the positive electrode metal foil 22, a foil made of a metal other than aluminum may be adopted.
As the negative electrode metal foil 26, a foil made of a metal other than copper may be adopted.

The positive electrode active material layer 23 may be located in the entire region other than the positive electrode tab 24 in the positive electrode 21.
○ Only one side of the positive electrode 21 may have the positive electrode active material layer 23.

  The outermost layer of the first electrode assembly 12a and the second electrode assembly 12b may be the positive electrode 21 having the positive electrode active material layer 23 only on one side. In this embodiment, the positive electrode active material layer 23 of the positive electrode 21 of the outermost layer of the first electrode assembly 12a and the second electrode assembly 12b is positioned on the inner side in the stacking direction of the electrode assemblies 12a and 12b. An outer layer positive electrode 21 is disposed. That is, one surface of the outermost positive electrode 21 of the first electrode assembly 12 a and the second electrode assembly 12 b that does not have the positive electrode active material layer 23 faces the thickness adjusting member 30. Thus, in the electrode assembly 12, the thickness adjusting member 30 is sandwiched from both sides in the stacking direction of the electrode assembly 12 by the surface of the positive electrode 21 that does not have the positive electrode active material layer 23.

The negative electrode active material layer 27 may be located in the entire region of the negative electrode 25 other than the negative electrode tab 28.
○ Only one surface of the negative electrode 25 may have the negative electrode active material layer 27.

  The secondary battery 10 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge.

The positive electrode 21, the negative electrode 25, the separator 29, and the thickness adjusting member 30 (thickness adjusting film 30a) may have a shape other than a rectangular shape such as a circular shape.
○ The shape of the case 11 may be changed. For example, the case 11 may be cylindrical.

  The present invention may be embodied in a power storage device such as an electric double layer capacitor.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 11 ... Case, 12 ... Electrode assembly, 12a ... 1st electrode assembly, 12b ... 2nd electrode assembly, 13 ... Case main body, 14 ... Lid body, 21 ... Positive electrode, 22 ... Positive electrode Metal foil, 23 ... positive electrode active material layer, 25 ... negative electrode, 26 ... negative electrode metal foil, 27 ... negative electrode active material layer, 29 ... separator, 30 ... thickness adjusting member, 30a ... thickness adjusting film.

Claims (6)

Case housing the positive electrode, an electrode assembly is stacked in a sandwiched therebetween and a negative electrode is a separator having an anode active material layer and the negative electrode tab, the electrode assembly comprising a positive electrode active material layer and the positive electrode tab A power storage device comprising:
The electrode assembly includes a first electrode assembly and a second electrode assembly in which the positive electrode and the negative electrode are stacked with the separator interposed therebetween,
The positive electrode tab of the positive electrode of the first electrode assembly and the positive electrode tab of the positive electrode of the second electrode assembly are electrically connected to each other;
The negative electrode tab of the negative electrode of the first electrode assembly and the negative electrode tab of the negative electrode of the second electrode assembly are electrically connected to each other;
In the stacking direction of the electrode assembly, a gap between the electrode assembly and the case is adjusted between the first electrode assembly and the second electrode assembly and in the center of the electrode assembly. A power storage device, wherein a thickness adjusting member for positioning is located.   The power storage device according to claim 1, wherein the thickness adjusting member includes a plurality of thickness adjusting films.   In the first electrode assembly and the second electrode assembly, the difference in the number of the positive electrodes constituting each of the first electrode assembly and the second electrode assembly is one or less, and the total number of the positive electrodes and the negative electrodes constituting the respective ones. The power storage device according to claim 1 or 2, wherein the difference is two or less.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a secondary battery. A method of manufacturing a power storage device including a positive electrode active material layer and electrode assembly and a negative electrode comprising a positive electrode and the negative electrode active material layer and the negative electrode tab having a positive electrode tab is stacked in a sandwiched therebetween a separator ,
The electrode assembly includes a first electrode assembly and a second electrode assembly in which the positive electrode and the negative electrode are stacked with the separator interposed therebetween,
Producing a plurality of the first electrode assemblies and the second electrode assemblies;
Measuring the lengths in the stacking direction of the plurality of first electrode assemblies and the second electrode assemblies manufactured;
More of the first electrode assembly and said second electrode assembly, the combination of the total length of the stacking direction is within a predetermined range with respect to the length of the inner dimension of the case housing the electrode assembly select the first electrode assembly and said second electrode assembly,
A thickness adjusting member is positioned between the first electrode assembly and the second electrode assembly in the stacking direction to stack the first electrode assembly and the second electrode assembly, and the first electrode assembly The positive electrode tab of the solid positive electrode and the positive electrode tab of the positive electrode of the second electrode assembly are electrically connected to each other, and the negative electrode tab of the negative electrode of the first electrode assembly and Electrically connecting the negative electrode tab of the second electrode assembly to the negative electrode tab of the second electrode assembly to produce one electrode assembly having the thickness adjusting member at the center in the stacking direction. Is stored in a case. A method for manufacturing a power storage device.   A power storage device comprising: an electrode assembly in which a positive electrode and a negative electrode including an active material layer are stacked with a separator interposed therebetween; and a case for housing the electrode assembly,
  The electrode assembly includes a first electrode assembly and a second electrode assembly in which the positive electrode and the negative electrode are stacked with the separator interposed therebetween,
  In the stacking direction of the electrode assembly, a gap between the electrode assembly and the case is adjusted between the first electrode assembly and the second electrode assembly and in the center of the electrode assembly. A thickness adjusting member is located,
  The power storage device, wherein the thickness adjusting member is not positioned between both end surfaces of the electrode assembly in the stacking direction and an inner surface of the case facing the electrode assembly.