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 winding step.SOLUTION: A manufacturing method of a wound electrode body 20 includes a winding step S11 of stacking and winding, around a winding core 111, a first separator 31, a negative electrode plate 25, a second separator 35 and a positive electrode plate 21. In the winding step S11, for an electrode plate 21 of at least one of the positive electrode plate 21 and the negative electrode plate 25, a position Px, in a width direction, of the electrode plate 21 during transportation is detected, and, on the basis of the detected position Px in the width direction and an estimated curvature amount Wn of the electrode plate 21, winding is performed while the position Px, in the width direction, of the electrode plate 21 is controlled such that the position Px in the width direction becomes a position Ps in a reference width direction.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a wound electrode body formed by stacking and 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 accommodated in a power storage device such as a battery or a capacitor, a cylindrical or flat wound electrode body formed by stacking and 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 end edge (edge) in the width direction of the electrode plate during conveyance. Based on the detected widthwise position, the widthwise position of the electrode plate is adjusted by edge position control (EPC) so that it becomes a predetermined reference widthwise position, while winding the electrode plate and the like. 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-described winding process may be curved in its width direction. When the electrode plate is curved, the greater the amount of curvature, the greater the winding deviation of the electrode plate. Therefore, depending solely on the position control of the electrode plate using the above-described edge sensor and EPC, the winding deviation of the electrode plate may not be sufficiently suppressed. In particular, if the conveyance speed of the electrode plate is increased to improve productivity, the control cannot keep up, and the winding deviation of the electrode plate cannot be suppressed.

[0006] The present invention has been made in view of such a situation, and provides a method for manufacturing a wound electrode body that can appropriately suppress the winding deviation of the electrode plate that may occur in the winding process, 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. In the winding process, for at least one of the positive electrode plate and the negative electrode plate, the width direction position of the electrode plate during conveyance is detected, and based on the detected width direction position and Rather than the actually measured amount of bending of the electrode body, the estimated amount of curvature of the electrode plate, the method is for manufacturing a wound electrode body in which the width direction position of the electrode plate is controlled so that the width direction position becomes a reference width direction position while winding.

[0008] In the above-described method for manufacturing a wound electrode body, in the winding process, based on the detected width direction position of the electrode plate and the estimated amount of curvature of this electrode plate, while controlling the width direction position of the electrode plate so that the width direction position becomes a reference width direction position, winding of the electrode plate and the like is performed. Therefore, compared with the case of controlling the width direction position of the electrode plate simply based on the detected width direction position without considering the amount of curvature of the electrode plate as in the prior art, the winding deviation of the electrode plate that may occur in the winding process can be appropriately suppressed. In addition, it may be difficult to actually measure the amount of curvature of each individual electrode plate used in the winding process 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 actually measured for 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.

[0009] Note that the "width direction position" of the electrode plate refers to a specific position in the width direction of the electrode plate, such as one end edge in the width direction or the center in the width direction. Further, as a method for detecting the width direction position of the electrode plate, for example, a method for detecting the width direction position of the electrode plate using a laser or a method for detecting the width direction position of the electrode plate using a camera can be mentioned. As a method for controlling the width direction position of the electrode plate so that the width direction position of the electrode plate becomes the reference width direction position, for example, by moving (sliding) the position adjustment roll that conveys the electrode plate along the roll axis direction or changing the inclination of the position adjustment roll, the width direction position of the electrode plate is moved so that the width direction position becomes the reference width direction position.

[0010] (2) Further, it is a method for manufacturing a wound electrode body according to (1), wherein the electrode plate is an electrode plate obtained by unwinding and cutting a long electrode plate that has been previously wound into a roll shape from an electrode roll, and the winding step includes, from the beginning of the unwinding of the electrode roll, a unwind length detection step of detecting the unwind length of the long electrode plate unwound up to the portion used in the winding step, and based on the detected unwind length, the amount of curvature of the innermost peripheral portion located at the innermost periphery of the electrode roll among the long electrode plate, which is the innermost peripheral curvature amount, and the amount of curvature of the outermost peripheral portion located at the initial outermost periphery of the electrode roll among 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 and obtaining the estimated amount of curvature.

[0011] 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 differs 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 circumference, and is the largest at the outermost circumference. Due to the change over time when the long electrode plate is wound into 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 circumference 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 differs for each electrode plate.

[0012] 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 curvature amount of the innermost circumferential portion of the long electrode plate, and the outermost circumferential curvature amount of the outermost circumferential portion of the long electrode plate, the amount of curvature of the electrode plate used in the winding process is estimated. Thereby, since the amount of curvature of each individual electrode plate can be appropriately estimated, by performing the winding process using this estimated amount of curvature, it is possible to more appropriately suppress the winding deviation of the electrode plate.

[0013] 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 curvature amount", it is preferable to use the amount of curvature 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 curvature amount", it is preferable to use the amount of curvature at the start of unwinding of the long electrode plate first unwound from the electrode roll, which was measured prior to performing the winding process.

[0014] (3) 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 step of manufacturing the wound electrode body by the method for manufacturing a wound electrode body described in (1) or (2), and a device assembly step of assembling the power storage device using the wound electrode body.

[0015] In the above method for manufacturing a power storage device, since a wound electrode body with suppressed winding displacement of the electrode plates can be formed in the electrode body manufacturing step, a power storage device including a wound electrode body with suppressed winding displacement of the electrode plates can be manufactured.

[0016] Note that 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 include a single wound electrode body or a plurality of wound electrode bodies.

Brief Description of Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0018] (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.

[0019] 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 case upper 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.

[0020] Among these, the case 10 is a rectangular parallelepiped box-shaped made of metal (aluminum in this embodiment), and includes a bottomed square 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 case upper 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 case upper portion 11, and is hermetically sealed with a disk-shaped sealing member 18 made of aluminum.

[0021] 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 installed 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 among the wound electrode bodies 20 within the case 10, while extending through the upper case portion 11 to the outside of the battery. Also, in the upper case portion 11, 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 case portion 11 via a resin member 55. This negative electrode terminal 50 is connected and conducts to the current collecting portion 25d of the negative electrode plate 25 among the wound electrode bodies 20 within the case 10, while extending through the upper case portion 11 to the outside of the battery.

[0022] 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 cylindrically, and then pressing them flat. The wound electrode body 20 is accommodated in the case 10 in a lying-down state. The first separator 31 and the second separator 35 are each made of a resin porous membrane.

[0023] The positive electrode plate 21 has a current collecting foil 22 made of strip-shaped aluminum foil. On both main surfaces of this current collecting foil 22, active material layers 23 containing positive electrode active material particles capable of occluding and releasing lithium ions are formed in a strip shape. Among the positive electrode plates 21, the portion where the active material layer 23 is formed on the current collecting foil 22 is the active material portion 21c. On the other hand, in one end of the positive electrode plate 21 in the width direction EH, the active material layer 23 does not exist on the current collecting foil 22, and the current collecting portion 21d where the current collecting foil 22 is exposed is formed. This current collecting portion 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.

[0024] 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 collection portion 25d where the current collector foil 26 is exposed without the active material layer 27 on the current collector foil 26. This current collection 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.

[0025] 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 9). 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. 7 and 5), a negative electrode roll (electrode roll) 25R, a first separator roll 31R, and a second separator roll 35R are prepared respectively.

[0026] The positive electrode roll 21R is obtained by previously winding a long 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 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 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 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 positive electrode plate 21Z” may be referred to as the “long electrode plate 21Z”, the “long 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”.

[0027] Here, the bending of the electrode plates 21 and 25 (long electrode plates 21Z and 25Z) will be described (see FIG. 8). As described above, the electrode plates 21 and 25 have active material portions 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 current collector portions 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 collector 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 circumference of the electrode rolls 21R and 25R.

[0028] 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 predetermined intervals 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. 8) connecting edge position A and edge position B, the distance in the width direction EH to edge position C 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.

[0029] 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 and 6). 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.

[0030] Among these, 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) is attached with 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). Each supply unit is configured to send out 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) 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 (the long first separator 31Z), the negative electrode plate 25 (the long negative electrode plate 25Z), the second separator 35 (the long second separator 35Z), and the positive electrode plate 21 (the long positive electrode plate 21Z) by overlapping them around the winding core 111.

[0031] The winding device 100 also includes cutting parts (a first separator cutting part 121, a negative electrode plate cutting part 122, a second separator cutting part 123, and a positive electrode plate cutting part 124) between each supply part (a first separator supply part 101, a negative electrode plate supply part 102, a second separator supply part 103, and a positive electrode plate supply part 104) and the winding part 110. These cutting parts are each configured to cut each long member (long first separator 31Z, long negative electrode plate 25Z, long second separator 35Z, and long positive electrode plate 21Z) in its width direction to cut out each member (first separator 31, negative electrode plate 25, second separator 35, and positive electrode plate 21).

[0032] Furthermore, the winding device 100 includes an edge sensor 130, a position adjustment mechanism 140, and a pay-out length detection part 150 in the conveyance path of the positive electrode plate 21 (long positive electrode plate 21Z). The winding device 100 also includes a control part 160. Among these, the edge sensor 130 is provided between the positive electrode plate cutting part 124 and the winding part 110 on the downstream side of the position adjustment mechanism 140, and detects the width direction position Px (see FIG. 6) of one edge (edge) in the width direction EH of the positive electrode plate 21 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 part 124, or on the upstream side of the position adjustment mechanism 140 (between the position adjustment mechanism 140 and the positive electrode plate supply part 104). Also, as the edge sensor 130, an edge sensor that uses a camera to detect the width direction position Px may be used.

[0033] The position adjustment mechanism 140 is provided between the positive electrode plate supply part 104 and the positive electrode plate cutting part 124 (see FIG. 5). The position adjustment mechanism 140 adjusts the width direction position Px of the positive electrode plate 21 while conveying the positive electrode plate 21 (see FIG. 6). 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. By changing the inclination of this position adjustment roll 141, the width direction position Px of the positive electrode plate 21 can be adjusted.

[0034] The unwinding length detection unit 150 is provided near the positive electrode plate supply unit 104 (see FIG. 5). The 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.

[0035] 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 the inclination of the position adjustment roll 141 in the position adjustment mechanism 140 is controlled based on the detection signals input from the edge sensor 130 and the unwinding length detection unit 150, respectively. A specific control method will be described later.

[0036] Next, the winding process S11 using the above-described winding device 100 will be described. In the "unwinding length detection process S111" (see FIG. 4) of the winding process S11, the unwinding length detection unit 150 (see FIG. 5) detects 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. For example, when 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 unwinding length L is detected as 1000 m.

[0037] Subsequently, in the "curvature amount estimation process S112" (see FIG. 4) of the winding process S11, the control unit 160 (see FIG. 5) estimates the curvature amount W of the positive electrode plate 21 used in the winding process S11 to obtain an estimated curvature amount Wn. Specifically, prior to attaching the positive electrode roll 21R to the winding device 100, the amount of curvature Wa of the innermost peripheral portion 21Za (see FIG. 7) located at the innermost circumference of the positive electrode roll 21R among the long positive electrode plates 21Z, which is the innermost peripheral curvature amount Wa, and the amount of curvature W of the outermost peripheral portion 21Zb located at the initial outermost circumference of the positive electrode roll 21R among the long positive electrode plates 21Z, which is the outermost peripheral curvature amount Wb, are measured respectively.

[0038] In this embodiment, the innermost peripheral curvature amount Wa is obtained by actually measuring the amount of curvature W at the start of winding portion 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 amount of curvature W as the innermost peripheral curvature amount Wa of the innermost peripheral portion 21Za. Specifically, for the start of winding portion of the long positive electrode plate 21Z, the amount of deviation b in the width direction at the longitudinal length a = 2000 mm is measured (see FIG. 8), and the innermost peripheral curvature amount Wa is obtained by Wa = b / a. For example, when the amount of deviation b in the width direction is b = 0.5 mm, the innermost peripheral curvature amount Wa = 0.5 / 2000 = 0.00025.

[0039] Also, the outermost peripheral curvature amount Wb is obtained by actually measuring the amount of curvature W at the start of unwinding portion 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 amount of curvature W as the outermost peripheral curvature amount Wb of the outermost peripheral portion 21Zb. Specifically, for the start of unwinding portion of the long positive electrode plate 21Z, the amount of deviation b in the width direction at the longitudinal length a = 2000 mm is measured (see FIG. 8), and the outermost peripheral curvature amount Wb is obtained by Wb = b / a. For example, when the amount of deviation b in the width direction is b = 3.0 mm, the innermost peripheral curvature amount Wa = 3.0 / 2000 = 0.0015. Then, prior to performing the winding process S11 using the winding device 100, the respective values of the above-mentioned innermost peripheral curvature amount Wa and outermost peripheral curvature amount Wb (in the above example, Wa = 0.00025, Wb = 0.0015) are input into the winding device 100, and these values are stored in the control unit 160.

[0040] In the bending amount estimation step S112, the control unit 160 estimates the bending amount W of the positive electrode plate 21 used in the winding step S11 based on the winding length L of the long positive electrode plate 21Z detected by the unwinding length detection unit 150, the innermost circumferential bending amount Wa and the outermost circumferential bending amount Wb previously stored in the control unit 160, and obtains 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 with different values of the innermost circumferential bending amount Wa and the outermost circumferential bending amount Wb to obtain a relational expression (approximate curve) RE between the winding length L of the long positive electrode plate 21Z and the bending amount W (see FIG. 9). Then, by substituting the winding length L, the innermost circumferential bending amount Wa, and the outermost circumferential 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 winding length L = 1000 m, the estimated bending amount Wn = 0.00075 is obtained.

[0041] In the winding step S11, the width direction position Px of the positive electrode plate 21 being conveyed is detected, and based on the detected width direction position Px and the estimated bending amount Wn of the positive electrode plate 21, the positive electrode plate 21 is wound while controlling the width direction position Px of the positive electrode plate 21 so that it becomes a predetermined reference width direction position Ps (see FIGS. 5 and 6). 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 positive electrode plate 21 detected by the edge sensor 130 and the reference width direction position Ps is obtained. Then, based on this difference (Px - Ps) and the magnitude of the above-described estimated bending amount Wn estimated by the control unit 160, the inclination of the position adjustment roll 141 is changed in the position adjustment mechanism 140 (see FIG. 6) so that the width direction position Px becomes the reference width direction position Ps, and the width direction position Px of the positive electrode plate 21 is controlled (PID control). Note that appropriate values for each parameter of this PID control are obtained by performing a preliminary experiment in advance. By performing the winding step S11 in this way, the positive electrode plate 21 can be wound around the winding core 111 together with the negative electrode plate 25 etc. while setting the width direction position Px of the positive electrode plate 21 as the reference width direction position Ps, so that the winding deviation of the positive electrode plate 21 can be appropriately suppressed.

[0042] Regarding the end of winding of the cylindrical wound electrode body 20Y, when the long positive electrode plate 21Z is cut by the positive electrode plate cutting portion 124 to cut out the positive electrode plate 21, the long negative electrode plate 25Z is cut by the negative electrode plate cutting portion 122 to cut out the negative electrode plate 25 so that the end of winding of the negative electrode plate 25 is longer than the end of winding of the positive electrode plate 21. Further, the long first separator 31Z is cut by the first separator cutting portion 121 to cut out the first separator 31 so that the end of winding of the first separator 31 and the second separator 35 located on the outermost circumference of the cylindrical wound electrode body 20Y are longer than the end of winding of the negative electrode plate 25, respectively. At the same time, the long second separator 35Z is cut by the second separator cutting portion 123 to cut out the second separator 35. After the winding of the cylindrical wound electrode body 20Y is completed, the end of winding of the first separator 31 located on the outermost circumference of the cylindrical wound electrode body 20Y is fixed to the cylindrical wound electrode body 20Y with an adhesive tape (not shown).

[0043] Next, in the "pressing step S12" (see FIG. 4) of the electrode body manufacturing process S1, 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).

[0044] Next, in the "device assembly step S2" (see FIG. 4), the battery 1 is assembled using the above-mentioned wound electrode body 20. First, the 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.

[0045] 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 opening 15c of the main body member 15 is closed with the lid member 16. 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 poured 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 the 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.

[0046] As described above, in the method for manufacturing the wound electrode body 20, in the winding step S11, based on the detected widthwise position Px of the positive electrode plate 21 and the estimated bending amount Wn of the positive electrode plate 21, the winding is performed while controlling the widthwise position Px of the positive electrode plate 21 so that the widthwise position Px becomes the reference widthwise position Ps. For this reason, compared with the case where the widthwise position Px of the positive electrode plate 21 is controlled simply based on the detected widthwise position Px without considering the bending amount of the positive electrode plate 21 as in the prior art, the winding deviation of the positive electrode plate 21 that may occur in the winding step S11 can be appropriately suppressed. Further, for each individual positive electrode plate 21 used in the winding step S11, instead of the actually measured bending amount, the estimated bending amount Wn is used, so it is not necessary to obtain the actually measured bending amount of the positive electrode plate 21.

[0047] Furthermore, 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 estimated bending amount Wr 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 winding step S11 using this estimated bending amount Wn, the winding deviation of the positive electrode plate 21 can be more appropriately suppressed.

[0048] Also, in the method for manufacturing the battery 1, since the wound electrode body 20 with the winding deviation of the positive electrode plate 21 suppressed can be formed in the electrode body manufacturing step S1, the battery 1 including the wound electrode body 20 with the winding deviation of the positive electrode plate 21 suppressed can be manufactured.

[0049] (Modified form) Next, a modified form of the above embodiment will be described (see FIG. 10). Note that descriptions of parts similar to those in 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 positive electrode plate 21 was adjusted by the position adjustment roll 141 whose inclination could be changed. In contrast, in the position adjustment mechanism 240 of the winding device 200 according to this modified form, the width direction position Px of the positive electrode plate 21 is adjusted by the position adjustment roll 241 that can move (slide) along the roll axis RX, which is different.

[0050] Specifically, as shown in FIG. 10, the position adjustment mechanism 240 of this modified form has a position adjustment roll 241 configured to be movable along the roll axis RX. Then, by moving this position adjustment roll 241 along the roll axis RX, the width direction position Px of the positive electrode plate 21 is adjusted, and the width direction position Px is set as the reference width direction position Ps. Also in this modified form, compared with the case where the width direction position Px of the positive electrode plate 21 is controlled simply based on the detected width direction position Px without considering the amount of curvature W of the positive electrode plate 21 as in the prior art, the winding deviation of the positive electrode plate 21 that can occur in the winding step S11 can be appropriately suppressed. In addition, parts similar to those in the embodiment have the same effects as those in the embodiment.

[0051] As described above, the present invention has been described with reference to the embodiment and the modified form. However, it goes without saying that the present invention is not limited to the embodiment and the modified form, and can be appropriately changed and applied without departing from the gist thereof. For example, in the embodiment, the present invention was applied only to the conveyance of the positive electrode plate 21 in order to suppress the winding deviation of the positive electrode plate 21 in the winding step S11. This is because the current collecting foil 26 (copper foil) of the negative electrode plate 25 is harder to deform than the current collecting foil 22 (aluminum foil) of the positive electrode plate 21, so the negative electrode plate 25 has a small amount of curvature W and a small winding deviation in the winding step S11. However, in order to more appropriately suppress the winding deviation of the negative electrode plate 25, the present invention may be applied to the conveyance of the negative electrode plate 25.

Explanation of Reference Numerals

[0052] 1 Battery (Power Storage Device) 20 Reeled electrode body 20Y Cylindrical reeled electrode body 21 Positive electrode plate (electrode plate) 21Z Long positive electrode plate (long electrode plate) 21Za Innermost peripheral part (of the long positive electrode plate) 21Zb Outermost peripheral part (of the long positive electrode plate) 21R Positive electrode roll (electrode roll) 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 Rewinding device S1 Electrode plate manufacturing process S11 Rewinding process S111 Unwinding length detection process S112 Bending amount estimation process S2 Device assembly process L Unwinding length W Bending amount Wa Innermost peripheral bending amount Wb Outermost peripheral bending amount Wn Estimated bending amount Px Width direction position Ps Reference width direction position

Claims

1. A method for manufacturing a wound electrode body formed by stacking and 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 while stacking them; the winding step includes: detecting the widthwise position of at least one of the positive electrode plate and the negative electrode plate during conveyance; while controlling the widthwise position of the electrode plate so that the widthwise position becomes a reference widthwise position based on the detected widthwise position and the estimated bending amount of the electrode plate, rather than the actually measured bending amount of the electrode body, winding is performed; A method for manufacturing a wound electrode body.

2. A method for manufacturing a wound electrode body according to Claim 1, wherein: the electrode plate is an electrode plate obtained by unwinding and cutting a long electrode plate from an electrode roll in which the long electrode plate has been previously wound in a roll shape; the winding step includes: a unwind length detection step of detecting the unwind length of the long electrode plate unwound from the beginning of unwinding of the electrode roll to the portion used in the winding step; the detected unwind length and the bending amount at the innermost circumferential portion located at the innermost circumference of the electrode roll among the long electrode plates, which is the innermost circumferential bending amount, and the bending amount at the outermost circumferential portion located at the initial outermost circumference of the electrode roll among the long electrode plates, which is the outermost circumferential bending amount, based on estimating the bending amount of the electrode plate used in the winding step to obtain the estimated bending amount; a bending amount estimation step, and has A method for manufacturing a wound electrode body.

3. A method for manufacturing a power storage device including a wound electrode body formed by stacking and winding a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each in a strip shape, comprising: 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; a device assembly step of assembling the power storage device using the wound electrode body; A method for manufacturing a power storage device.

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