Method for manufacturing a wound electrode body and method for manufacturing a power storage device

Abstract

To provide a manufacturing method of a wound electrode body, and the like, the manufacturing method being capable of appropriately preventing occurrence of winding deviation of an electrode plate which may occur during a residual winding step in a winding step.SOLUTION: A manufacturing method of a wound electrode body 20 includes a winding step S11. The winding step S11 includes: a main winding step S111 of winding up while controlling a position Px of a long electrode plate 21Z in a width direction; a cutting step S115 of cutting the long electrode plate 21Z; a residual winding step S116 of winding an unwound part 21f of the electrode plate 21; and a position adjustment step S114 of, after the main winding step S111 and before the cutting step S115, adjusting the position Px of the long electrode plate 21Z in the width direction such that the position Px of the unwound part 21f in the width direction becomes a position Ps in a reference width direction in the residual winding step S116, on the basis of a curvature amount W of the electrode plate 21.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a wound electrode body formed by winding a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each in a strip shape, and a method for manufacturing a power storage device including the wound electrode body.

Background Art

[0002] As an electrode body housed in a power storage device such as a battery or a capacitor, a cylindrical or flat wound electrode body formed by winding a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each in a strip shape, is known. In the manufacture of this wound electrode body, when winding the first separator, the negative electrode plate, the second separator, and the positive electrode plate around a winding core, winding deviation may occur in one or both of the positive electrode plate and the negative electrode plate.

[0003] Conventionally, to address this problem, an edge sensor is used to detect the widthwise position of one edge (edge) of the electrode plate in the width direction during conveyance, and based on this detected widthwise position, while adjusting the widthwise position of the electrode plate by edge position control (EPC) so that the widthwise position becomes a predetermined reference widthwise position, the electrode plate and the like are wound. Thereby, winding deviation of the electrode plate has been suppressed. As a related prior art, for example, Patent Document 1 can be cited (see FIG. 1 etc. of Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the strip-shaped electrode plate used in the above winding process may be curved in its width direction. If the electrode plate is curved, this curvature also causes misalignment of the electrode plate during winding. In particular, in the remaining winding process of winding up the unwound portion of the electrode plate after cutting the long electrode plate, since the long electrode plate has already been cut, no tension is applied to the unwound portion of the electrode plate during conveyance, and significant misalignment occurs in this unwound portion (the portion disposed near the outer periphery of the completed wound electrode body). It has been found that the magnitude of this misalignment is related to the magnitude of the curvature of the electrode plate (specifically, the greater the curvature of the electrode plate, the greater the misalignment of the unwound portion).

[0006] The present invention has been made in view of such a situation, and provides a method for manufacturing a wound electrode body capable of appropriately suppressing misalignment of an electrode plate that may occur in the remaining winding process among the winding processes, and a method for manufacturing a power storage device including the wound electrode body.

Means for Solving the Problems

[0007] (1) One aspect of the present invention for solving the above problems is a method for manufacturing a wound electrode body formed by winding a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each having a strip shape, around a winding core. The winding process includes winding the first separator, the negative electrode plate, the second separator, and the positive electrode plate around the winding core. The winding process includes a main winding process of winding the long electrode plate before cutting, which becomes a plurality of electrode plates of either the positive electrode plate or the negative electrode plate by cutting, while controlling the width direction position of the long electrode plate during conveyance so that the width direction position of the long electrode plate during conveyance becomes a reference width direction position, a cutting process of cutting the long electrode plate in the width direction at the winding end of the electrode plate to cut out the electrode plate, and a remaining winding process of winding up the unwound portion of the cut electrode plate. After the main winding process and before the cutting process, instead of controlling the width direction position in the main winding process, a position adjustment process is further provided for adjusting the width direction position of the long electrode plate based on the curvature amount of the electrode plate so that the width direction position of the unwound portion in the remaining winding process becomes the reference width direction position. This is a method for manufacturing a wound electrode body.

[0008] In the method for manufacturing the wound electrode body described above, in the position adjustment step after the main winding step and before the cutting step, based on the amount of curvature of the electrode plate, the widthwise position of the long electrode plate is adjusted in advance so that the widthwise position of the unwound portion of the electrode plate in the remaining winding step becomes the reference widthwise position. As a result, in the remaining winding step, the unwound portion of the electrode plate can be wound while the widthwise position of the unwound portion of the electrode plate is the reference widthwise position, so that the winding deviation of the electrode plate in the unwound portion can be appropriately suppressed.

[0009] Note that the "widthwise position" of the long electrode plate or the electrode plate refers to a specific position in the width direction, such as one end edge in the width direction or the center in the width direction of the long electrode plate or the like. Further, as a method for detecting the widthwise position of the long electrode plate or the like, for example, a method for detecting the widthwise position using a laser or a method for detecting the widthwise position using a camera can be mentioned. As a method for controlling the widthwise position of the long electrode plate so that the widthwise position of the long electrode plate becomes the reference widthwise position in the main winding step, for example, a position adjustment roll for conveying the long electrode plate is moved (slid) in the roll axis direction, or the inclination of the position adjustment roll is changed to move the widthwise position of the long electrode plate so that the widthwise position becomes the reference widthwise position. The "amount of curvature" of the electrode plate used in the winding step may be the actually measured amount of curvature or the estimated amount of curvature.

[0010] (2) Further, it is a method for manufacturing a wound electrode body according to (1), wherein the main winding step is performed using a position adjustment mechanism for adjusting the widthwise position of the long electrode plate, and the position adjustment step is a method for manufacturing a wound electrode body performed using the above position adjustment mechanism.

[0011] In the method for manufacturing the wound electrode body described above, the main winding step is performed using a position adjustment mechanism, and the position adjustment step is also performed using the position adjustment mechanism used in the main winding step, so that a separate device or the like for performing the position adjustment step is not required.

[0012] (3) Further, it is a method for manufacturing a wound electrode body according to (1) or (2), wherein in the position adjustment step, as the amount of curvature of the electrode plate, the estimated amount of curvature of the electrode plate is used to adjust the position in the width direction of the long electrode plate, which is a good method for manufacturing a wound electrode body.

[0013] It may be difficult to actually measure the amount of curvature of each individual electrode plate used in the winding step from the viewpoints of measurement accuracy and production cost. In contrast, in the above-described manufacturing method, instead of the actually measured amount of curvature of the electrode body, the estimated amount of curvature is used, so it is not necessary to obtain the actually measured amount of curvature of the electrode body.

[0014] (4) Further, it is a method for manufacturing a wound electrode body according to (3), wherein the long electrode plate is unwound from an electrode roll in which the long electrode plate is wound in a roll shape in advance, and the winding step includes a winding length detection step of detecting the winding length of the long electrode plate unwound from the start of unwinding of the electrode roll to the portion used in the winding step, and based on the detected winding length, the amount of curvature at the innermost peripheral portion located at the innermost circumference of the electrode roll in the long electrode plate, which is the innermost peripheral curvature amount, and the amount of curvature at the outermost peripheral portion located at the initial outermost circumference of the electrode roll in the long electrode plate, which is the outermost peripheral curvature amount, a curvature amount estimation step of estimating the amount of curvature of the electrode plate used in the winding step to obtain the estimated amount of curvature, which is a good method for manufacturing a wound electrode body.

[0015] In an electrode roll in which a long electrode plate is wound in a roll shape, the amount of curvature of the long electrode plate is different between the inner peripheral side and the outer peripheral side. Specifically, it has been found that the amount of curvature of the long electrode plate is the smallest at the innermost circumference, increases toward the outer periphery, and is the largest at the outermost periphery. Due to the change over time when the long electrode plate is wound in a roll shape or during the storage period of the electrode roll, it is considered that the amount of curvature of the long electrode plate increases toward the outer periphery of the electrode roll. Therefore, even between electrode plates cut after unwinding the long electrode plate from the same electrode roll, the amount of curvature is different for each electrode plate.

[0016] On the other hand, in the method for manufacturing the wound electrode body described above, the unwinding length of the long electrode plate from the electrode roll is detected, and based on this unwinding length, the innermost circumferential bending amount of the innermost circumferential portion of the long electrode plate, and the outermost circumferential bending amount of the outermost circumferential portion of the long electrode plate, the bending amount of the electrode plate used in the winding process is estimated. Thereby, since the bending amount of each electrode plate can be appropriately estimated, by performing the position adjustment process using this estimated bending amount, the winding deviation of the electrode plate that may occur in the residual winding process can be more appropriately suppressed.

[0017] Note that the "unwinding length" can be calculated, for example, based on the rotation angle of the electrode roll from the time when the long electrode plate starts to be unwound from the electrode roll. Also, the unwinding length can be calculated based on the conveyance speed of the long electrode plate and the conveyance time of the long electrode plate from the time when the long electrode plate starts to be unwound from the electrode roll. For the "innermost circumferential bending amount", it is preferable to use the bending amount at the start of winding of the long electrode plate, which was measured in advance before starting to wind the long electrode plate as an electrode roll. Also, for the "outermost circumferential bending amount", it is preferable to use the bending amount at the start of unwinding of the long electrode plate that was first unwound from the electrode roll, which was measured prior to performing the winding process.

[0018] (5) Another aspect is a method for manufacturing a power storage device including a wound electrode body formed by winding a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each in a strip shape, which includes an electrode body manufacturing process for manufacturing the wound electrode body by the method for manufacturing a wound electrode body according to any one of (1) to (4), and a device assembly process for assembling the power storage device using the wound electrode body.

[0019] In the method for manufacturing the power storage device described above, since a wound electrode body with suppressed winding deviation of the electrode plate in the unwound portion can be formed in the electrode body manufacturing process, a power storage device including a wound electrode body with suppressed winding deviation of the electrode plate in the unwound portion can be manufactured.

[0020] Incidentally, examples of the "power storage device" include secondary batteries such as lithium ion secondary batteries, capacitors such as lithium ion capacitors, and all solid-state batteries. The power storage device may have a single wound electrode body or a plurality of wound electrode bodies.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0022] (Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the drawings. A perspective view of a battery (power storage device) 1 according to this embodiment is shown in FIG. 1, a perspective view of a wound electrode body 20 included in the battery 1 is shown in FIG. 2, and a developed view of the wound electrode body 20 is shown in FIG. 3. In the following, the battery height direction AH, the battery width direction BH, and the battery thickness direction CH of the battery 1 are defined as the directions shown in FIG. 1 for explanation. This battery 1 is a rectangular (cuboid-shaped) and sealed lithium-ion secondary battery mounted on vehicles such as hybrid cars, plug-in hybrid cars, and electric vehicles.

[0023] The battery 1 includes a case 10, a flat wound electrode body 20 housed in the case 10, a positive electrode terminal 40 and a negative electrode terminal 50 respectively supported on the upper case portion 11 of the case 10, and the like. The wound electrode body 20 is covered in the case 10 with a bag-shaped insulating holder (not shown) made of an insulating film. Further, an electrolytic solution 3 is housed in the case 10, a part of which is impregnated in the wound electrode body 20, and the rest accumulates on the case bottom portion 12 of the case 10.

[0024] Among these, the case 10 is a rectangular parallelepiped box-shaped made of metal (aluminum in this embodiment), and includes a bottomed rectangular tube-shaped main body member 15 having a rectangular annular opening 15c on the upper side AH1 in the battery height direction AH, and a rectangular plate-shaped lid member 16 laser-welded to the main body member 15 over the entire circumference in a form of closing the opening 15c. The lid member 16 forming the upper case portion 11 is provided with a safety valve 17 that breaks and opens when the internal pressure of the case 10 exceeds the opening pressure. Further, a liquid injection hole 16k communicating the inside and outside of the case 10 is provided in the upper case portion 11, and is hermetically sealed with a disk-shaped sealing member 18 made of aluminum.

[0025] Furthermore, in the upper case portion 11, near the end of one side BH1 in the battery width direction BH, a positive electrode terminal 40 made of aluminum is fixedly provided in a state of being insulated from the upper case portion 11 via a resin member 45. This positive electrode terminal 40 is connected and conducts to the current collecting portion 21d of the positive electrode plate 21 in the wound electrode body 20 in the case 10, and extends through the upper case portion 11 to the outside of the battery. In addition, in the upper part 11 of the case, near the end of the other side BH2 in the battery width direction BH, a negative electrode terminal 50 made of copper is fixedly installed in a state of being insulated from the upper part 11 of the case via a resin member 55. This negative electrode terminal 50 is connected to and conducts with the current collecting part 25d of the negative electrode plate 25 among the wound electrode bodies 20 inside the case 10, while extending through the upper part 11 of the case to the outside of the battery.

[0026] Next, the wound electrode body 20 will be described. This wound electrode body 20 is formed by stacking a strip-shaped first separator 31, a strip-shaped negative electrode plate (electrode plate) 25, a strip-shaped second separator 35, and a strip-shaped positive electrode plate (electrode plate) 21, winding them into a cylindrical shape, and then pressing them into a flat shape. The wound electrode body 20 is accommodated in the case 10 in a horizontally laid state. The first separator 31 and the second separator 35 are each made of a resin porous membrane.

[0027] The positive electrode plate 21 has a current collecting foil 22 made of a strip-shaped aluminum foil. On both main surfaces of this current collecting foil 22, active material layers 23 each containing positive electrode active material particles capable of occluding and releasing lithium ions are formed in a strip shape. Among the positive electrode plate 21, the part where the active material layer 23 is formed on the current collecting foil 22 is the active material part 21c. On the other hand, one end of the positive electrode plate 21 in the width direction EH is a current collecting part 21d where the current collecting foil 22 is exposed without the active material layer 23 on the current collecting foil 22. This current collecting part 21d protrudes in a spiral shape on one side BH1 in the battery width direction BH of the wound electrode body 20 and is connected to the positive electrode terminal 40 as described above.

[0028] The negative electrode plate 25 has a current collector foil 26 made of a strip-shaped copper foil. On both main surfaces of this current collector foil 26, active material layers 27 each containing negative electrode active material particles capable of occluding and releasing lithium ions are formed in a strip shape. Among the negative electrode plate 25, the portion where the active material layer 27 is formed on the current collector foil 26 is the active material portion 25c. On the other hand, one end of the negative electrode plate 25 in the width direction EH is a current collector portion 25d where the current collector foil 26 is exposed without the active material layer 27. This current collector portion 25d protrudes in a spiral shape to the other side BH2 in the battery width direction BH of the wound electrode body 20 and is connected to the negative electrode terminal 50 as described above.

[0029] Next, a method for manufacturing the wound electrode body 20 and a method for manufacturing the battery 1 using this wound electrode body 20 will be described (see FIGS. 4 to 10). First, in the "electrode body manufacturing step S1" (see FIG. 4), the wound electrode body 20 (see FIG. 2) is manufactured. Specifically, first, a positive electrode roll (electrode roll) 21R (see FIGS. 8 and 5), a negative electrode roll (electrode roll) 25R, a first separator roll 31R, and a second separator roll 35R are prepared respectively.

[0030] The positive electrode roll 21R is obtained by previously winding a long strip-shaped positive electrode plate (long electrode plate) 21Z (about 4000 m in length) that becomes a plurality of positive electrode plates 21 (about 4 m in length) by cutting into a roll shape. The negative electrode roll 25R (about 4 m in length) is obtained by previously winding a long strip-shaped negative electrode plate (long electrode plate) 25Z (about 4000 m in length) that becomes a plurality of negative electrode plates 25 by cutting into a roll shape. The first separator roll 31R is obtained by previously winding a long strip-shaped first separator 31Z (about 4000 m in length) that becomes a plurality of first separators 31 (about 4 m in length) by cutting into a roll shape. The second separator roll 35R is obtained by previously winding a long strip-shaped second separator 35Z (about 4000 m in length) that becomes a plurality of second separators 35 (about 4 m in length) by cutting into a roll shape. Hereinafter, the "long strip-shaped positive electrode plate 21Z" may be referred to as the "long electrode plate 21Z", the "long strip-shaped negative electrode plate 25Z" may be referred to as the "long electrode plate 25Z", the "positive electrode plate 21" may be referred to as the "electrode plate 21", and the "negative electrode plate 25" may be referred to as the "electrode plate 25".

[0031] Here, the bending of the electrode plates 21 and 25 (long electrode plates 21Z and 25Z) will be described (see Fig. 9). As described above, the electrode plates 21 and 25 have an active material portion 21c and 25c in which active material layers 23 and 27 are formed on both main surfaces of current collector foils 22 and 26, and a current collecting portion 21d and 25d composed only of the current collector foils 22 and 26. The electrode plates 21 and 25 are roll-pressed to increase the density of the active material layers 23 and 27. During this roll pressing, among the current collector foils 22 and 26, the portions forming the active material portions 21c and 25c are rolled and extended in the longitudinal direction DH by roll pressing, while the portions forming the current collecting portions 21d and 25d have no active material layers 23 and 27 and hardly receive press pressure, so they hardly extend. For this reason, the roll-pressed electrode plates 21 and 25 are curved in the width direction EH. Furthermore, due to the tension applied when the long electrode plates 21Z and 25Z are wound into a roll shape to form the electrode rolls 21R and 25R, and the temporal change due to the tension applied during the storage period of the wound electrode rolls 21R and 25R, it has been found that the bending amount W of the long electrode plates 21Z and 25Z increases toward the outer periphery of the electrode rolls 21R and 25R.

[0032] In this embodiment, the bending amount W of the electrode plates 21 and 25 (long electrode plates 21Z and 25Z) is defined as follows. That is, for three edge positions (edge position A, edge position C, edge position B) arranged at a predetermined interval in the longitudinal direction DH of the electrode plates 21 and 25, the length of the longitudinal direction DH from edge position A to edge position B is the longitudinal direction length a, and from the virtual straight line D (shown by a broken line in Fig. 9) connecting edge position A and edge position B to edge position C, the distance in the width direction EH is defined as the width direction deviation amount b, and the width direction deviation amount b with respect to the longitudinal direction length a is defined as the bending amount W (= b / a). For example, when the longitudinal direction length a = 2000 mm and the width direction deviation amount b = 2.0 mm, the bending amount W = 2.0 / 2000 = 0.0010.

[0033] In the electrode body manufacturing process S1, first, in the "winding process S11" (see FIG. 4), around the cylindrical winding core 111, the first separator 31, the negative electrode plate 25, the second separator 35, and the positive electrode plate 21 are stacked in this order and wound cylindrically to form a cylindrical wound electrode body 20Y. This winding process S11 is performed using a winding device 100 (see FIGS. 5 to 7). The winding device 100 includes a first separator supply unit 101, a negative electrode plate supply unit 102, a second separator supply unit 103, a positive electrode plate supply unit 104, and a winding unit 110.

[0034] Among these, in each supply unit (the first separator supply unit 101, the negative electrode plate supply unit 102, the second separator supply unit 103, and the positive electrode plate supply unit 104), the aforementioned respective rolls (the first separator roll 31R, the negative electrode roll 25R, the second separator roll 35R, and the positive electrode roll 21R) are attached. Each supply unit is configured to send out each long member (long first separator 31Z, long negative electrode plate 25Z, long second separator 35Z, and long positive electrode plate 21Z) from each roll toward the winding unit 110. Also, in the conveyance path of each long member from each supply unit to the winding unit 110, a plurality of conveyance rollers (not shown) for conveying each long member are provided. On the other hand, the winding core 111 is attached to the winding unit 110. The winding unit 110 is configured to wind and take up the first separator 31 (long first separator 31Z), the negative electrode plate 25 (long negative electrode plate 25Z), the second separator 35 (long second separator 35Z), and the positive electrode plate 21 (long positive electrode plate 21Z) around this winding core 111 in a stacked manner.

[0035] Further, the winding device 100 includes cutting portions (a first separator cutting portion 121, a negative electrode plate cutting portion 122, a second separator cutting portion 123, and a positive electrode plate cutting portion 124) between each supply portion (the first separator supply portion 101, the negative electrode plate supply portion 102, the second separator supply portion 103, and the positive electrode plate supply portion 104) and the winding portion 110. These cutting portions are each configured to cut each long member (the long first separator 31Z, the long negative electrode plate 25Z, the long second separator 35Z, and the long positive electrode plate 21Z) in its width direction to cut out each member (the first separator 31, the negative electrode plate 25, the second separator 35, and the positive electrode plate 21).

[0036] Furthermore, the winding device 100 includes an edge sensor 130, a position adjustment mechanism 140, and a payout length detection unit 150 in the conveyance path of the long positive electrode plate 21Z (positive electrode plate 21). The winding device 100 also includes a control unit 160. Among these, the edge sensor 130 is provided between the positive electrode plate cutting portion 124 and the winding portion 110 on the downstream side of the position adjustment mechanism 140, and detects the width direction position Px (see FIG. 7) of one end edge (edge) in the width direction EH of the long positive electrode plate 21Z during conveyance. In the present embodiment, as the edge sensor 130, an edge sensor that uses a laser to detect the width direction position Px is used. Note that the installation position of the edge sensor 130 is not limited to the above. For example, the edge sensor 130 can also be provided between the position adjustment mechanism 140 and the positive electrode plate cutting portion 124, or on the upstream side of the position adjustment mechanism 140 (between the position adjustment mechanism 140 and the positive electrode plate supply portion 104). Also, as the edge sensor 130, an edge sensor that uses a camera to detect the width direction position Px may be used.

[0037] The position adjustment mechanism 140 is provided between the positive electrode plate supply portion 104 and the positive electrode plate cutting portion 124 (see FIG. 5). The position adjustment mechanism 140 adjusts the width direction position Px of the long positive electrode plate 21Z while conveying the long positive electrode plate 21Z (see FIG. 7). The position adjustment mechanism 140 of the present embodiment has a position adjustment roll 141 configured to be able to change the inclination of the roll axis RX. Then, by changing the inclination of this position adjustment roll 141, the width direction position Px of the long positive electrode plate 21Z can be adjusted.

[0038] The unwinding length detection unit 150 is provided near the positive electrode plate supply unit 104 (see FIG. 5). This unwinding length detection unit 150 is configured to detect the unwinding length L of the long positive electrode plate 21Z that has been unwound from the beginning of the unwinding of the positive electrode roll 21R to the portion used in the winding process S11. In the present embodiment, the unwinding length L is calculated based on the rotation angle θ of the positive electrode roll 21R from the time when the unwinding of the long positive electrode plate 21Z from the positive electrode roll 21R starts. Note that a configuration may be adopted in which the unwinding length L is calculated based on the conveyance speed of the long positive electrode plate 21Z and the conveyance time from the time when the unwinding of the long positive electrode plate 21Z from the positive electrode roll 21R starts.

[0039] The control unit 160 includes a CPU, a ROM, and a RAM (not shown), and has a microcomputer that operates according to a predetermined control program stored in the ROM or the like. The edge sensor 130, the position adjustment mechanism 140, the unwinding length detection unit 150, etc. are connected to the control unit 160, and based on the detection signals input from the edge sensor 130 and the unwinding length detection unit 150 respectively, the inclination of the position adjustment roll 141 in the position adjustment mechanism 140 is controlled. The specific control method will be described later.

[0040] Next, the winding process S11 using the above-described winding device 100 will be described. In the "main winding process S111" (see FIG. 4) of the winding process S11, while controlling the width direction position Px of the long positive electrode plate 21Z so that the width direction position Px of the long positive electrode plate 21Z being conveyed becomes the reference width direction position Ps, the long positive electrode plate 21Z etc. are wound (see FIGS. 5, 6(a), and 7).

[0041] Specifically, the width direction position Px of the long positive electrode plate 21Z during conveyance is detected, and based on the detected width direction position Px, while controlling the width direction position Px of the long positive electrode plate 21Z so that the width direction position Px becomes a predetermined reference width direction position Ps, it is wound. Specifically, since the reference width direction position Ps is stored in the control unit 160, the difference (Px - Ps) between the width direction position Px of the long positive electrode plate 21Z detected by the edge sensor 130 and the reference width direction position Ps is obtained. Then, based on the magnitude of this difference (Px - Ps), the inclination of the position adjustment roll 141 in the position adjustment mechanism 140 is changed (see FIG. 7) so that the width direction position Px becomes the reference width direction position Ps, and the width direction position Px of the long positive electrode plate 21Z is controlled (PID control). By performing the main winding step S111 in this way, while setting the width direction position Px of the long positive electrode plate 21Z as the reference width direction position Ps, the long positive electrode plate 21Z can be wound around the winding core 111 together with the long negative electrode plate 25Z, etc., so that the winding deviation of the long positive electrode plate 21Z in the main winding step S111 can be appropriately suppressed.

[0042] Subsequently, the "position adjustment step S114" is performed immediately before performing the "cutting step S115" (see FIG. 4). In this position adjustment step S114, instead of controlling the width direction position Px of the long positive electrode plate 21Z in the above-described main winding step S111, the width direction position Px of the long positive electrode plate 21Z is adjusted in preparation for the subsequent remaining winding step S116 (see FIGS. 5 and 7). That is, based on the bending amount W of the positive electrode plate 21 used in the winding step S11, in the remaining winding step S116, the width direction position Px of the long positive electrode plate 21Z is adjusted so that the width direction position Px of the unwound portion 21f of the cut positive electrode plate 21 becomes the reference width direction position Ps.

[0043] Prior to this position adjustment step S114, in the "winding length detection step S112" (see FIG. 4), the winding length L of the long positive electrode plate 21Z that has been wound from the beginning of the unwinding of the positive electrode roll 21R to the portion used in the winding step S11 is detected by the winding length detection unit 150 (see FIG. 5). For example, in a state where 1 / 4 of the long positive electrode plate 21Z with a length of about 4000 m is unwound from the positive electrode roll 21R on which the long positive electrode plate 21Z is wound, the winding length L is detected as 1000 m.

[0044] Subsequently, in the "bending amount estimation step S113" (see FIG. 4), in the control unit 160 (see FIG. 5), the bending amount W of the positive electrode plate 21 used in the winding step S11 is estimated to obtain an estimated bending amount Wn. Specifically, prior to attaching the positive electrode roll 21R to the winding device 100, among the long positive electrode plates 21Z, the innermost bending amount Wa which is the bending amount W at the innermost peripheral portion 21Za (see FIG. 8) located at the innermost circumference of the positive electrode roll 21R, and the outermost bending amount Wb which is the bending amount W at the outermost peripheral portion 21Zb located at the initial outermost circumference of the positive electrode roll 21R among the long positive electrode plates 21Z are each measured.

[0045] In this embodiment, the innermost bending amount Wa is obtained by actually measuring the bending amount W at the start portion of winding of the long positive electrode plate 21Z before starting to wind up the long positive electrode plate 21Z after roll pressing as the positive electrode roll 21R, and using this bending amount W as the innermost bending amount Wa of the innermost peripheral portion 21Za. Specifically, for the start portion of winding of the long positive electrode plate 21Z, the width direction deviation amount b at the longitudinal length a = 2000 mm is measured (see FIG. 9), and the innermost bending amount Wa is obtained by Wa = b / a. For example, when the width direction deviation amount b = 0.5 mm, the innermost bending amount Wa = 0.5 / 2000 = 0.00025.

[0046] Also, the outermost bending amount Wb is obtained by actually measuring the bending amount W at the start portion of unwinding of the long positive electrode plate 21Z first unwound from the positive electrode roll 21R immediately before attaching the positive electrode roll 21R to the winding device 100, and using this bending amount W as the outermost bending amount Wb of the outermost peripheral portion 21Zb. Specifically, for the start portion of unwinding of the long positive electrode plate 21Z, the width direction deviation amount b at the longitudinal length a = 2000 mm is measured (see FIG. 9), and the outermost bending amount Wb is obtained by Wb = b / a. For example, when the width direction deviation amount b = 3.0 mm, the innermost bending amount Wa = 3.0 / 2000 = 0.0015. Then, prior to performing the winding step S11 using the winding device 100, the respective values of the above-described innermost bending amount Wa and outermost bending amount Wb (in the above example, Wa = 0.00025, Wb = 0.0015) are input to the winding device 100, and these values are stored in the control unit 160.

[0047] In the bending amount estimation step S113, in the control unit 160, based on the unwinding length L of the long positive electrode plate 21Z detected by the unwinding length detection unit 150, and the innermost circumference bending amount Wa and the outermost circumference bending amount Wb previously stored in the control unit 160, the bending amount W of the positive electrode plate 21 used in the winding step S11 is estimated to obtain an estimated bending amount Wn. Specifically, in the present embodiment, a preliminary experiment is performed in advance using a plurality of positive electrode rolls 21R having different values of the innermost circumference bending amount Wa and the outermost circumference bending amount Wb to obtain a relational expression (approximate curve) RE between the unwinding length L of the long positive electrode plate 21Z and the bending amount W (see FIG. 10). Then, by substituting the unwinding length L, the innermost circumference bending amount Wa, and the outermost circumference bending amount Wb into this relational expression RE, the estimated bending amount Wn of the positive electrode plate 21 is calculated. For example, when the unwinding length L = 1000 m, the estimated bending amount Wn = 0.00075 is obtained.

[0048] In the position adjustment step S114, based on this estimated bending amount Wn, in order to suppress the winding deviation of the unwound portion 21f of the positive electrode plate 21 in the remaining winding step S116 described later, the width direction position Px of the long positive electrode plate 21Z is adjusted. Specifically, based on the magnitude of the estimated bending amount Wn, the inclination of the position adjustment roll 141 is changed in the position adjustment mechanism 140 (see FIG. 7) to adjust the width direction position Px of the long positive electrode plate 21Z. Note that, with respect to the magnitude of the estimated bending amount Wn, how much the inclination of the position adjustment roll 141 is changed is obtained by performing a preliminary experiment in advance to obtain an appropriate value.

[0049] Subsequently, in the "cutting step S115" (see FIG. 4), the long positive electrode plate 21Z is cut in the width direction EH at the winding end 21e of the positive electrode plate 21 to cut out the positive electrode plate 21 (see FIGS. 6(b) and 5). Also, the long negative electrode plate 25Z is cut by the negative electrode plate cutting portion 122 so that the winding end of the negative electrode plate 25 is longer than the winding end of the positive electrode plate 21e, and the negative electrode plate 25 is cut out. Further, the long first separator 31Z is cut by the first separator cutting portion 121 so that the winding ends of the first separator 31 and the second separator 35 are longer than the winding end of the negative electrode plate 25, respectively, to cut out the first separator 31, and the long second separator 35Z is cut by the second separator cutting portion 123 to cut out the second separator 35.

[0050] Subsequently, in the "remaining winding step S116" (see FIG. 4), the unwound portion 21f of the cut positive electrode plate 21 is wound together with the unwound portion 31f of the first separator 31, the unwound portion 25f of the negative electrode plate 25, and the unwound portion 35f of the second separator 35 (see FIGS. 6(b) and 5). At this time, in the above-described position adjustment step S114, since the width direction position Px of the long positive electrode plate 21Z is adjusted in advance in preparation for this remaining winding step S116, it is possible to suppress the occurrence of winding deviation in the unwound portion 21f of the positive electrode plate 21 in the remaining winding step S116. After the cylindrical wound electrode body 20Y is wound, the winding end of the first separator 31 located on the outermost periphery of the cylindrical wound electrode body 20Y is fixed to the cylindrical wound electrode body 20Y with an adhesive tape (not shown).

[0051] Next, in the "pressing step S12" (see FIG. 4) of the electrode body manufacturing step S10, the cylindrical wound electrode body 20Y taken out from the winding device 100 is pressed and crushed using a pressing device (not shown) to form a flat wound electrode body 20 (see FIG. 2).

[0052] Next, in the "device assembly process S2" (see FIG. 4), the battery 1 is assembled using the above-described wound electrode body 20. First, resin members 45 and 55 are formed by insert molding using the lid member 16, the positive electrode terminal 40, and the negative electrode terminal 50, and the positive electrode terminal 40 and the negative electrode terminal 50 are fixed to the lid member 16 via the resin members 45 and 55 (see FIG. 1). Next, the positive electrode terminal 40 and the negative electrode terminal 50 are ultrasonically welded to the positive and negative current collecting portions 21d and 25d of the wound electrode body 20, respectively.

[0053] Next, the wound electrode body 20 is wrapped with a bag-shaped insulating holder (not shown), and these are inserted into the main body member 15, and the lid member 16 closes the opening 15c of the main body member 15. Then, the opening 15c of the main body member 15 and the lid member 16 are laser welded over the entire circumference to form the case 10. Next, the electrolytic solution 3 is injected into the case 10 through the liquid injection hole 16k, and the electrolytic solution 3 is impregnated into the wound electrode body 20. Thereafter, the liquid injection hole 16k is covered with a sealing member 18 from the outside, and the sealing member 18 is laser welded to the case 10. Thereafter, for this battery 1, initial charging, aging, various inspections, etc. are performed. Thus, the battery 1 is completed.

[0054] As described above, in the manufacturing method of the wound electrode body 20, in the position adjustment step S114 after the main winding step S111 and before the cutting step S115, based on the bending amount W of the positive electrode plate 21 used in the winding step S11, the width direction position Px of the unrolled portion 21f of the positive electrode plate 21 in the remaining winding step S116 is set to the reference width direction position Ps. The width direction position Px of the long positive electrode plate 21Z is adjusted in advance. Thereby, in the remaining winding step S116, the unrolled portion 21f of the positive electrode plate 21 can be wound while the width direction position Px of the unrolled portion 21f of the positive electrode plate 21 is set to the reference width direction position Ps, so that the winding deviation of the positive electrode plate 21 in the unrolled portion 21f can be appropriately suppressed.

[0055] Furthermore, in the present embodiment, the main winding step S111 is performed using the position adjustment mechanism 140, and the position adjustment step S114 is also performed using the position adjustment mechanism 140 used in the main winding step S111. Therefore, a separate device or the like for performing the position adjustment step S114 is not required. Also, in the present embodiment, for each individual positive electrode plate 21 used in the winding step S11, the estimated bending amount Wn is used instead of the actually measured bending amount Wr, so it is not necessary to obtain the actually measured bending amount Wr of the positive electrode plate 21.

[0056] Also, in the present embodiment, the unwinding length L of the long positive electrode plate 21Z from the positive electrode roll 21R is detected, and based on this unwinding length L, the innermost circumferential bending amount Wa of the innermost circumferential portion 21Za of the long positive electrode plate 21Z, and the outermost circumferential bending amount Wb of the outermost circumferential portion 21Zb of the long positive electrode plate 21Z, the bending amount W of the positive electrode plate 21 used in the winding step S11 is estimated. Thereby, the bending amount W of each individual positive electrode plate 21 can be appropriately estimated. Therefore, by performing the position adjustment step S114 using this estimated bending amount Wn, the winding deviation of the positive electrode plate 21 that may occur in the remaining winding step S116 can be more appropriately suppressed.

[0057] Also, in the method for manufacturing the battery 1, since the wound electrode body 20 in which the winding deviation of the positive electrode plate 21 in the unwound portion 21f is suppressed can be formed in the electrode body manufacturing step S1, the battery 1 including the wound electrode body 20 in which the winding deviation of the positive electrode plate 21 in the unwound portion 21f is suppressed can be manufactured.

[0058] (Modified form) Next, a modified form of the above embodiment will be described (see FIG. 11). Note that the description of the parts similar to the embodiment will be omitted or simplified. In the position adjustment mechanism 140 of the winding device 100 according to the embodiment, the width direction position Px of the long positive electrode plate 21Z is adjusted by the position adjustment roll 141 whose inclination can be changed. On the other hand, in the position adjustment mechanism 240 of the winding device 200 according to the present modified form, the width direction position Px of the long positive electrode plate 21Z is adjusted by the position adjustment roll 241 that can move (slide) along the roll axis RX, which is different.

[0059] Specifically, as shown in FIG. 11, the position adjustment mechanism 240 of this modified form has a position adjustment roll 241 configured to be movable along the roll axis RX. By moving this position adjustment roll 241 along the roll axis RX, the widthwise position Px of the long positive electrode plate 21Z is adjusted. By performing the position adjustment step S114 using this position adjustment mechanism 240, even in this modified form, in the remaining winding step S116, the unwound portion 21f of the positive electrode plate 21 can be wound up while setting the widthwise position Px of the unwound portion 21f as the reference widthwise position Ps. For this reason, the winding deviation of the positive electrode plate 21 in the unwound portion 21f can be appropriately suppressed. In addition, parts similar to those in the embodiment exhibit the same operational effects as those in the embodiment.

[0060] As described above, the present invention has been described in accordance with the embodiments and modified forms. However, the present invention is not limited to the embodiments and modified forms, and it goes without saying that it can be appropriately changed and applied without departing from the gist thereof. For example, in the embodiment, the position adjustment step S114 was performed on the long positive electrode plate 21Z in order to suppress the winding deviation of the unwound portion 21f of the positive electrode plate 21 in the remaining winding step S116. The current collector foil 26 (copper foil) of the negative electrode plate 25 is harder to deform compared to the current collector foil 22 (aluminum foil) of the positive electrode plate 21. Therefore, the negative electrode plate 25 has a small amount of curvature W and also has a small winding deviation in the remaining winding step S116. However, in order to more appropriately suppress the winding deviation of the unwound portion 25f of the negative electrode plate 25 in the remaining winding step S116, the position adjustment step S114 may be performed on the long negative electrode plate 25Z.

[0061] Also, in the embodiment, as the amount of curvature W of the positive electrode plate 21 used in the position adjustment step S114, the estimated estimated amount of curvature Wn of the positive electrode plate 21 is used, but the actually measured amount of curvature Wr of the positive electrode plate 21 can also be used. Specifically, a plurality of edge sensors are provided between the positive electrode plate supply unit 104 and the position adjustment mechanism 140 of the winding device 100 (see FIG. 5). By detecting the edge position of the long positive electrode plate 21Z unwound from the positive electrode roll 21R of the positive electrode plate supply unit 104 and conveyed toward the position adjustment mechanism 140, the actually measured amount of curvature Wr can be obtained.

Explanation of Symbols

[0062] 1 Battery (Power Storage Device) 20 Wound Electrode Body 20Y Cylindrically Wound Electrode Body 21 Positive Electrode Plate (Electrode Plate) 21Z Long Positive Electrode Plate (Long Electrode Plate) 21Za Innermost Circumferential Portion (of the Long Positive Electrode Plate) 21Zb Outermost Circumferential Portion (of the Long Positive Electrode Plate) 21R Positive Electrode Roll (Electrode Roll) 21e End of Winding 21f Unwound Portion 25 Negative Electrode Plate (Electrode Plate) 25Z Long Negative Electrode Plate (Long Electrode Plate) 25R Negative Electrode Roll (Electrode Roll) 31 First Separator 35 Second Separator 100, 200 Winding Device S1 Electrode Plate Manufacturing Process S11 Winding Process S111 Main Winding Process S112 Wound - out Length Detection Process S113 Bending Amount Estimation Process S114 Position Adjustment Process S115 Cutting Process S116 Remaining Winding Process S2 Device Assembly Process L Wound - out Length W Bending Amount Wa Innermost Circumferential Bending Amount Wb Outermost Circumferential Bending Amount Wn Estimated Bending Amount Wr Measured Bending Amount Px Width - Direction Position Ps Reference Width - Direction Position

Claims

1. A method for manufacturing a wound electrode body formed by winding a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each in a strip shape, comprising a winding step of winding the first separator, the negative electrode plate, the second separator, and the positive electrode plate around a winding core, wherein the winding step includes a main winding step of winding a long electrode plate before being cut into a plurality of electrode plates, which is either the positive electrode plate or the negative electrode plate, while controlling the widthwise position of the long electrode plate during conveyance so that the widthwise position of the long electrode plate becomes a reference widthwise position, a cutting step of cutting the long electrode plate in the width direction at the winding end of the electrode plate to cut out the electrode plate, and a remaining winding step of winding up the unwound portion of the cut electrode plate, and after the main winding step and before the cutting step, instead of controlling the widthwise position in the main winding step, based on the amount of curvature of the electrode plate, a position adjustment step of adjusting the widthwise position of the long electrode plate is further included so that the widthwise position of the unwound portion in the remaining winding step becomes the reference widthwise position A method for manufacturing a wound electrode body.

2. A method for manufacturing a wound electrode body according to Claim 1, wherein the main winding step is performed using a position adjustment mechanism for adjusting the widthwise position of the long electrode plate, and the position adjustment step is performed using the position adjustment mechanism A method for manufacturing a wound electrode body.

3. A method for manufacturing a wound electrode body according to Claim 1 or Claim 2, wherein the position adjustment step uses the estimated amount of curvature of the electrode plate as the amount of curvature of the electrode plate to adjust the widthwise position of the long electrode plate A method for manufacturing a wound electrode body.

4. A method for manufacturing a wound electrode body according to Claim 3, wherein the long electrode plate is unwound from an electrode roll in which the long electrode plate is previously wound in a roll shape, and the winding step includes a winding length detection step of detecting the winding length of the long electrode plate unwound from the beginning of the unwinding of the electrode roll to the portion used in the winding step, the detected winding length, the amount of curvature at the innermost peripheral portion located at the innermost periphery of the electrode roll in the long electrode plate, which is the innermost peripheral curvature amount, and based on the amount of curvature at the outermost peripheral portion located at the initial outermost periphery of the electrode roll in the long electrode plate, which is the outermost peripheral curvature amount, a curvature amount estimation step of estimating the amount of curvature of the electrode plate used in the winding step to obtain the estimated amount of curvature A method for manufacturing a wound electrode body. Method for manufacturing a wound electrode body.

5. A method for manufacturing a power storage device including a wound electrode body formed by winding a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each in a strip shape, an electrode body manufacturing step of manufacturing the wound electrode body by the method for manufacturing a wound electrode body according to claim 1 or claim 2, and a device assembly step of assembling the power storage device using the wound electrode body. Method for manufacturing a power storage device.

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