JP7701904B2 - Manufacturing method of wound electrode body and manufacturing method of electric storage device - Google Patents

Description

The present invention relates to a method for manufacturing a wound electrode assembly in which a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each of which is strip-shaped, are stacked and wound, and a method for manufacturing an electric storage device including the wound electrode assembly.

As an electrode body to be housed in an electric storage device such as a battery or a capacitor, a cylindrical or flat wound electrode body is known, in which a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each of which is in the shape of a strip, are stacked and wound. In manufacturing this wound electrode body, when the first separator, the negative electrode plate, the second separator, and the positive electrode plate are stacked and wound around the winding core, a winding misalignment may occur in one or both of the positive and negative electrode plates.

To address this problem, conventionally, an edge sensor is used to detect the widthwise position of one edge of the electrode plate during transport, and based on this detected widthwise position, the widthwise position of the electrode plate is adjusted by edge position control (EPC) so that the widthwise position becomes a predetermined reference widthwise position while winding the electrode plate. This prevents the electrode plate from being misaligned when wound. For example, Patent Document 1 can be cited as an example of related prior art (see Figure 1 of Patent Document 1, etc.).

JP 2003-297412 A

However, the belt-shaped electrode plate used in the winding process described above may be curved in the width direction. If the electrode plate is curved, this curvature can also cause misalignment of the electrode plate. In particular, in the remaining winding process in which the unwound portion of the electrode plate is wound after the long electrode plate has been cut, the long electrode plate has already been cut, so no tension is applied to the unwound portion of the electrode plate during transport, and this causes a large misalignment in the unwound portion (the portion that is located near the outer periphery of the completed wound electrode body). It has been found that the magnitude of this misalignment is related to the amount of curvature of the electrode plate (specifically, the greater the amount of curvature of the electrode plate, the greater the misalignment in the unwound portion).

The present invention has been made in consideration of the current situation, and provides a method for manufacturing a wound electrode assembly that can appropriately suppress winding misalignment of the electrode plate that can occur during the remaining winding process of the winding process, and a method for manufacturing an electricity storage device that includes a wound electrode assembly.

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

In the above-mentioned method for manufacturing a wound electrode body, after the main winding process and before the cutting process, the widthwise position of the long electrode plate is adjusted in advance based on the amount of curvature of the electrode plate in the position adjustment process so that the widthwise position of the unwound portion of the electrode plate in the remaining winding process becomes the reference widthwise position. As a result, in the remaining winding process, the unwound portion can be wound while the widthwise position of the unwound portion of the electrode plate is set to the reference widthwise position, so that the winding misalignment of the electrode plate in the unwound portion can be appropriately suppressed.

The "width direction position" of a long electrode plate or an electrode plate refers to a specific position in the width direction, such as one edge in the width direction or the center in the width direction, of a long electrode plate, etc. Examples of a method for detecting the width direction position of a long electrode plate, etc. include a method for detecting the width direction position using a laser and a method for detecting the width direction position using a camera.
In this winding process, a method for controlling the widthwise position of the long electrode plate so that it coincides with the reference widthwise position may include, for example, moving (sliding) the position adjustment roll that transports the long electrode plate in the roll axis direction or changing the inclination of the position adjustment roll to move the widthwise position of the long electrode plate and set the widthwise position to the reference widthwise position.
The "amount of curvature" of the electrode plate used in the winding step may be an actually measured amount of curvature or an estimated amount of curvature.

(2) In the method for manufacturing the wound electrode body described in (1), the main winding process may be performed using a position adjustment mechanism that adjusts the widthwise position of the long electrode plate, and the position adjustment process may be performed using the position adjustment mechanism.

In the above-mentioned method for manufacturing a wound electrode body, the main winding process is performed using a position adjustment mechanism, and the position adjustment process is also performed using the position adjustment mechanism used in the main winding process, so there is no need for a separate device or the like to perform the position adjustment process.

(3) In the method for manufacturing the wound electrode body described in (1) or (2), the position adjustment process may further comprise a method for manufacturing the wound electrode body in which the estimated amount of curvature of the electrode plate is used as the amount of curvature of the electrode plate to adjust the widthwise position of the long electrode plate.

Actually measuring the amount of curvature of each electrode plate used in the winding process can be difficult in terms of measurement accuracy and production costs. In contrast, the above-mentioned manufacturing method uses an estimated amount of curvature rather than an actual measured amount of curvature for the electrode body, so there is no need to obtain the actual measured amount of curvature for the electrode body.

(4) The method for manufacturing a wound electrode body described in (3) may further include a step of detecting the unwound length of the long electrode plate, which is unwound from an electrode roll in which the long electrode plate has been wound in a roll shape in advance, and the winding step may include a step of detecting the unwound length of the long electrode plate, which is unwound from the beginning of unwinding the electrode roll to the portion used in the winding step, and a step of estimating the amount of curvature of the electrode plate to be used in the winding step based on the detected unwound length, an innermost curvature amount, which is the amount of curvature at the innermost portion of the long electrode plate located at the innermost portion of the electrode roll, and an outermost curvature amount, which is the amount of curvature at the outermost portion of the long electrode plate located at the initial outermost portion of the electrode roll, to obtain the estimated amount of curvature.

In an electrode roll made by winding a long electrode plate into a roll, the amount of curvature of the long electrode plate differs between the inner and outer circumferences. Specifically, it has been found that the amount of curvature of the long electrode plate is smallest at the innermost circumference, larger toward the outer circumference, and largest at the outermost circumference. It is thought that the amount of curvature of the long electrode plate becomes greater toward the outer circumference of the electrode roll when the long electrode plate is wound into a roll and due to changes over time during the storage period of the electrode roll. Therefore, even electrode plates that are unwound and cut from the same electrode roll have different amounts of curvature for each electrode plate.

In contrast, in the above-mentioned method for manufacturing a wound electrode body, the unwound length of the long electrode plate from the electrode roll is detected, and the amount of curvature of the electrode plate used in the winding process is estimated based on this unwound length, the amount of innermost curvature of the innermost part of the long electrode plate, and the amount of outermost curvature of the outermost part of the long electrode plate. This allows the amount of curvature of each electrode plate to be appropriately estimated, and by performing the position adjustment process using this estimated amount of curvature, it is possible to more appropriately suppress winding misalignment of the electrode plate that may occur in the remaining winding process.

The "unrolling length" can be calculated, for example, based on the rotation angle of the electrode roll from the point when the long electrode plate starts to be unrolled from the electrode roll. The unrolling length can also be calculated based on the transport speed of the long electrode plate and the transport time of the long electrode plate from the point when the long electrode plate starts to be unrolled from the electrode roll.
The "amount of curvature at the innermost periphery" is preferably the amount of curvature at the start of winding the long electrode plate, which is measured in advance before starting to wind the long electrode plate into an electrode roll.
Furthermore, for the "outermost circumference curvature amount", it is preferable to use the curvature amount at the start of unwinding of the long electrode plate first unwound from the electrode roll, measured prior to the winding step.

(5) Another aspect is a method for manufacturing an electricity storage device having 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 of which is in the shape of a strip, and the method for manufacturing an electricity storage device may include an electrode body manufacturing process for manufacturing the wound electrode body by the wound electrode body manufacturing method described in any one of (1) to (4), and a device assembly process for assembling the electricity storage device using the wound electrode body.

The above-mentioned method for manufacturing an electric storage device can form a wound electrode body in which the winding misalignment of the electrode plate in the unwound portion is suppressed during the electrode body manufacturing process, so that an electric storage device can be manufactured that includes a wound electrode body in which the winding misalignment of the electrode plate in the unwound portion is suppressed.

The "electricity storage device" may be, for example, a secondary battery such as a lithium ion secondary battery, a capacitor such as a lithium ion capacitor, or an all-solid-state battery. The electricity storage device may include a single or multiple wound electrode bodies.

FIG. 1 is a perspective view of a battery according to an embodiment. FIG. 2 is a perspective view of a wound electrode body according to the embodiment. FIG. 2 is a development view of a wound electrode body according to the embodiment. 4 is a flowchart of a method for manufacturing a battery including a method for manufacturing a wound electrode assembly according to an embodiment. FIG. 2 is an explanatory diagram of a winding device that performs a winding step in the embodiment. FIG. 1A is an explanatory diagram showing how a long positive electrode plate is wound in a main winding process according to an embodiment, and FIG. 1B is an explanatory diagram showing how an unwound portion of an already cut positive electrode plate is wound in a remaining winding process. 10A to 10C are explanatory diagrams illustrating adjustment of the width direction position of a long positive electrode plate in the embodiment. FIG. 2 is an explanatory diagram of a positive electrode roll in the embodiment. 11 is an explanatory diagram showing a bending amount W of an electrode plate. FIG. 1 is a graph showing the relationship between the unwound length L and the amount of curvature W of a long positive electrode plate that constitutes a positive electrode roll. 13A and 13B are explanatory diagrams showing adjustment of the width direction position of a long positive electrode plate according to a modified embodiment.

(Embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a perspective view of a battery (electricity storage device) 1 according to this embodiment, Fig. 2 shows a perspective view of a wound electrode body 20 provided in the battery 1, and Fig. 3 shows a developed view of the wound electrode body 20. In the following, the battery height direction AH, battery width direction BH, and battery thickness direction CH of the battery 1 are defined as the directions shown in Fig. 1. The battery 1 is a rectangular (rectangular) sealed lithium ion secondary battery that is mounted on vehicles such as hybrid cars, plug-in hybrid cars, and electric cars.

The battery 1 is composed of a case 10, a flat wound electrode body 20 housed in the case 10, and a positive electrode terminal 40 and a negative electrode terminal 50 each supported on the case top 11 of the case 10. Inside the case 10, the wound electrode body 20 is covered by a bag-shaped insulating holder (not shown) made of insulating film. Also, the case 10 contains an electrolyte 3, a part of which is impregnated in the wound electrode body 20 and the remainder is stored on the case bottom 12 of the case 10.

Of these, the case 10 is a rectangular box made of metal (aluminum in this embodiment) and is composed of a bottomed, square cylindrical 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 cover member 16 that is laser welded to the main body member 15 around its entire circumference in a manner that closes the opening 15c.
A cover member 16 constituting 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 a valve opening pressure. A liquid injection hole 16k that communicates between the inside and outside of the case 10 is also provided in the case upper portion 11, and is airtightly sealed with a disk-shaped sealing member 18 made of aluminum.

Furthermore, a positive electrode terminal 40 made of aluminum is fixed to the case upper portion 11 near an end portion on one side BH1 in the width direction BH of the battery, insulated from the case upper portion 11 via a resin member 45. This positive electrode terminal 40 is connected to and conductively connected to the current collecting portion 21d of the positive electrode plate 21 of the wound electrode body 20 within the case 10, and also extends through the case upper portion 11 to the outside of the battery.
A negative electrode terminal 50 made of copper is fixed to the case upper portion 11 near the end portion on the other side BH2 in the width direction BH of the battery, insulated from the case upper portion 11 via a resin member 55. This negative electrode terminal 50 is connected to and conductive with the current collecting portion 25d of the negative electrode plate 25 of the wound electrode body 20 within the case 10, and also extends through the case upper portion 11 to the outside of the battery.

Next, the wound electrode body 20 will be described. The 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 housed in the case 10 in a laid-down state.
The first separator 31 and the second separator 35 are each made of a porous resin film.

The positive electrode plate 21 has a current collector foil 22 made of a strip-shaped aluminum foil. On both main surfaces of the current collector foil 22, active material layers 23 containing positive electrode active material particles capable of absorbing and releasing lithium ions are formed in a strip shape. The part of the positive electrode plate 21 where the active material layer 23 is formed on the current collector foil 22 is the active material portion 21c. On the other hand, one end of the positive electrode plate 21 in the width direction EH is a current collector portion 21d where the active material layer 23 is not present on the current collector foil 22 and the current collector foil 22 is exposed. This current collector portion 21d protrudes in a spiral shape on one side BH1 of the wound electrode body 20 in the battery width direction BH, and is connected to the positive electrode terminal 40 as described above.

The negative electrode plate 25 has a current collector 26 made of a strip-shaped copper foil. On both main surfaces of the current collector 26, a strip-shaped active material layer 27 containing negative active material particles capable of absorbing and releasing lithium ions is formed. The part of the negative electrode plate 25 where the active material layer 27 is formed on the current collector 26 is the active material part 25c. On the other hand, one end of the negative electrode plate 25 in the width direction EH is a current collector 25d where the active material layer 27 is not present on the current collector 26 and the current collector 26 is exposed. This current collector 25d protrudes in a spiral shape to the other side BH2 of the wound electrode body 20 in the battery width direction BH, and is connected to the negative electrode terminal 50 as described above.

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 assembly manufacturing process S1" (see FIG. 4), the wound electrode assembly 20 (see FIG. 2) is manufactured. Specifically, first, the positive electrode roll (electrode roll) 21R (see FIGS. 8 and 5), the negative electrode roll (electrode roll) 25R, the first separator roll 31R, and the second separator roll 35R are prepared.

The positive electrode roll 21R is a roll of a long positive electrode plate (long electrode plate) 21Z (length: about 4000 m) that will be cut into a plurality of positive electrode plates 21 (length: about 4 m). The negative electrode roll 25R (length: about 4 m) is a roll of a long negative electrode plate (long electrode plate) 25Z (length: about 4000 m) that will be cut into a plurality of negative electrode plates 25. The first separator roll 31R is a roll of a long first separator 31Z (length: about 4000 m) that will be cut into a plurality of first separators 31 (length: about 4 m). The second separator roll 35R is a roll of a long second separator 35Z (length: about 4000 m) that will be cut into a plurality of second separators 35 (length: about 4 m). In the following, 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."

Here, the curvature of the electrode plates 21, 25 (long electrode plates 21Z, 25Z) will be described (see FIG. 9). As described above, the electrode plates 21, 25 have active material parts 21c, 25c in which active material layers 23, 27 are formed on both main surfaces of the current collector foils 22, 26, and current collector parts 21d, 25d consisting only of the current collector foils 22, 26. The electrode plates 21, 25 are roll-pressed to increase the density of the active material layers 23, 27. During this roll-pressing, the parts of the current collector foils 22, 26 that form the active material parts 21c, 25c are rolled by the roll press and extend in the longitudinal direction DH, but the parts that form the current collector parts 21d, 25d do not have the active material layers 23, 27 and are hardly subjected to pressing pressure, so they do not extend much. For this reason, the roll-pressed electrode plates 21, 25 are curved in the width direction EH. Furthermore, it has been found that the amount of curvature W of the long electrode plates 21Z, 25Z increases toward the outer periphery of the electrode rolls 21R, 25R due to the tension applied when the long electrode plates 21Z, 25Z are wound into a roll to form the electrode rolls 21R, 25R, and due to changes over time caused by the tension applied during storage of the wound electrode rolls 21R, 25R.

In this embodiment, the curvature W of the electrode plates 21, 25 (long electrode plates 21Z, 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, 25, the length in the longitudinal direction DH from edge position A to edge position B is the longitudinal length a, the distance in the width direction EH from the virtual straight line D (shown by a dashed line in FIG. 9) connecting edge position A and edge position B to edge position C is the width direction deviation b, and the width direction deviation b relative to the longitudinal length a is the curvature W (= b/a). For example, when the longitudinal length a = 2000 mm and the width direction deviation b = 2.0 mm, the curvature W = 2.0/2000 = 0.0010.

In the electrode body manufacturing process S1, first, in the "winding process S11" (see FIG. 4), 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 around a cylindrical winding core 111 to form a cylindrical wound electrode body 20Y. This winding process S11 is performed using a winding device 100 (see FIG. 5 to FIG. 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.

Among these, the aforementioned rolls (first separator roll 31R, negative electrode roll 25R, second separator roll 35R, and positive electrode roll 21R) are attached to each of the supplying parts (first separator supplying part 101, negative electrode plate supplying part 102, second separator supplying part 103, and positive electrode plate supplying part 104). Each supplying part 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 part 110. In addition, a plurality of conveying rollers (not shown) that convey each long member are provided on the conveying path of each long member from each supplying part to the winding part 110.
On the other hand, a winding core 111 is attached to the winding unit 110. The winding unit 110 is configured to wind 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) in a stacked manner around the winding core 111.

The winding device 100 also includes cutting sections (first separator cutting section 121, negative electrode plate cutting section 122, second separator cutting section 123, and positive electrode plate cutting section 124) between each supply section (first separator supply section 101, negative electrode plate supply section 102, second separator supply section 103, and positive electrode plate supply section 104) and the winding section 110. These cutting sections are 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 their width direction to cut out each member (first separator 31, negative electrode plate 25, second separator 35, and positive electrode plate 21).

The winding device 100 further includes an edge sensor 130, a position adjustment mechanism 140, and an unwinding length detection unit 150 on the transport path of the long positive electrode plate 21Z (positive electrode plate 21).
Among these, the edge sensor 130 is provided downstream of the position adjustment mechanism 140 between the positive electrode plate cutting section 124 and the winding section 110, and detects the width direction position Px (see FIG. 7) of one end edge (edge) of the width direction EH of the long positive electrode plate 21Z being transported. In this embodiment, an edge sensor that detects the width direction position Px using a laser is used as the edge sensor 130. Note that the installation position of the edge sensor 130 is not limited to the above, and for example, the edge sensor 130 can be provided between the position adjustment mechanism 140 and the positive electrode plate cutting section 124 or upstream of the position adjustment mechanism 140 (between the position adjustment mechanism 140 and the positive electrode plate supply section 104). Also, an edge sensor that detects the width direction position Px using a camera may be used as the edge sensor 130.

The position adjustment mechanism 140 is provided between the positive electrode plate supply unit 104 and the positive electrode plate cutting unit 124 (see FIG. 5). The position adjustment mechanism 140 adjusts the widthwise position Px of the long positive electrode plate 21Z while transporting the long positive electrode plate 21Z (see FIG. 7). In this embodiment, the position adjustment mechanism 140 has a position adjustment roll 141 that is configured to be able to change the inclination of the roll axis RX. The widthwise position Px of the long positive electrode plate 21Z can be adjusted by changing the inclination of the position adjustment roll 141.

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 unwound from the beginning of unwinding the positive electrode roll 21R to the portion used in the winding process S11. In this embodiment, the unwinding length L is calculated based on the rotation angle θ of the positive electrode roll 21R from the point at which unwinding of the long positive electrode plate 21Z from the positive electrode roll 21R begins. Note that a configuration may be adopted in which the unwinding length L is calculated based on the transport speed of the long positive electrode plate 21Z and the transport time from the point at which unwinding of the long positive electrode plate 21Z from the positive electrode roll 21R begins.

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

Next, the winding process S11 using the above-mentioned winding device 100 will be described. In the "main winding process S111" (see FIG. 4) of the winding process S11, the long positive electrode plate 21Z and the like are wound while controlling the widthwise position Px of the long positive electrode plate 21Z during transport so that the widthwise position Px of the long positive electrode plate 21Z coincides with the reference widthwise position Ps (see FIG. 5, FIG. 6(a) and FIG. 7).

Specifically, the width direction position Px of the long positive electrode plate 21Z being transported is detected, and the long positive electrode plate 21Z is wound while being controlled so that the width direction position Px becomes a predetermined reference width direction position Ps based on the detected width direction position Px. In detail, the control unit 160 stores the reference width direction position Ps, and calculates 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. Then, based on the magnitude of this difference (Px-Ps), the inclination of the position adjustment roll 141 is changed in the position adjustment mechanism 140 (see FIG. 7) so that the width direction position Px becomes the reference width direction position Ps, thereby controlling (PID control) the width direction position Px of the long positive electrode plate 21Z.
By performing the main winding process S111 in this manner, the widthwise position Px of the long positive electrode plate 21Z can be set to the reference widthwise position Ps, while 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 winding misalignment of the long positive electrode plate 21Z in the main winding process S111 can be appropriately suppressed.

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

Prior to this position adjustment step S114, in the "unwinding length detection step S112" (see FIG. 4), the unwinding length detection unit 150 (see FIG. 5) detects the unwound length L of the long positive electrode plate 21Z unwound from the beginning of unwinding the positive electrode roll 21R to the portion to be used in the winding step S11. For example, when a quarter of the long positive electrode plate 21Z has been unwound from the positive electrode roll 21R that has wound up a long positive electrode plate 21Z with a length of approximately 4000 m, the unwound length L is detected as 1000 m.

Next, in the "curve amount estimation step S113" (see FIG. 4), the control unit 160 (see FIG. 5) estimates the curvature W of the positive electrode plate 21 used in the winding step S11 to obtain an estimated curvature Wn. Specifically, prior to mounting the positive electrode roll 21R to the winding device 100, the innermost curvature Wa, which is the curvature W at the innermost portion 21Za (see FIG. 8) located at the innermost periphery of the positive electrode roll 21R, of the long positive electrode plate 21Z, and the outermost curvature Wb, which is the curvature W at the outermost portion 21Zb located at the initial outermost periphery of the positive electrode roll 21R, of the long positive electrode plate 21Z, are measured.

In this embodiment, the amount of curvature Wa at the innermost periphery is determined by actually measuring the amount of curvature W at the start of winding the long positive electrode plate 21Z after roll pressing before starting to wind the long positive electrode plate 21Z into the positive electrode roll 21R, and this amount of curvature W is set as the amount of curvature Wa at the innermost periphery of the innermost periphery. Specifically, for the start of winding the long positive electrode plate 21Z, the amount of widthwise deviation b at a longitudinal length a = 2000 mm is measured (see Figure 9), and the amount of innermost curvature Wa is calculated by Wa = b/a. For example, when the amount of widthwise deviation b = 0.5 mm, the amount of innermost curvature Wa = 0.5/2000 = 0.00025.

The outermost curvature Wb is determined by actually measuring the curvature W at the start of unwinding of the long positive electrode plate 21Z that is first unwound from the positive electrode roll 21R immediately before mounting the positive electrode roll 21R on the winding device 100, and using this curvature W as the outermost curvature Wb of the outermost portion 21Zb. Specifically, for the start of unwinding of the long positive electrode plate 21Z, the widthwise deviation b at a longitudinal length a of 2000 mm is measured (see FIG. 9), and the outermost curvature Wb is calculated by Wb=b/a. For example, when the widthwise deviation b=3.0 mm, the innermost curvature Wa=3.0/2000=0.0015.
Then, prior to performing the winding process S11 using the winding device 100, the values of the innermost circumference curvature amount Wa and the outermost circumference curvature amount Wb described above (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.

In the curvature amount estimation process S113, the control unit 160 estimates the curvature amount W of the positive electrode plate 21 to be used in the winding process S11 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 curvature amount Wa and the outermost circumference curvature amount Wb that have been stored in advance in the control unit 160, and obtains an estimated curvature amount Wn.
Specifically, in this embodiment, a preliminary experiment is performed in advance using a plurality of positive electrode rolls 21R having different values of the innermost periphery curvature Wa and the outermost periphery curvature Wb to obtain a relational expression (approximate curve) RE between the unwound length L and the curvature W of the long positive electrode plate 21Z (see FIG. 10). Then, the unwound length L, the innermost periphery curvature Wa, and the outermost periphery curvature Wb are respectively substituted into this relational expression RE to calculate the estimated curvature Wn of the positive electrode plate 21. For example, when the unwound length L is 1000 m, the estimated curvature Wn is calculated as 0.00075.

In the position adjustment process S114, the widthwise position Px of the long positive electrode plate 21Z is adjusted based on the estimated amount of curvature Wn to suppress winding misalignment of the unwound portion 21f of the positive electrode plate 21 in the remaining winding process S116 described below. Specifically, based on the magnitude of the estimated amount of curvature Wn, the inclination of the position adjustment roll 141 in the position adjustment mechanism 140 is changed (see FIG. 7) to adjust the widthwise position Px of the long positive electrode plate 21Z. Note that a preliminary experiment is conducted in advance to obtain an appropriate value for the degree to which the inclination of the position adjustment roll 141 is changed relative to the magnitude of the estimated amount of curvature Wn.

Next, in the "cutting step S115" (see FIG. 4), the long positive plate 21Z is cut in the width direction EH at the winding end 21e of the positive plate 21 to cut out the positive plate 21 (see FIG. 6(b) and FIG. 5). The long negative plate 25Z is cut by the negative plate cutting unit 122 to cut out the negative plate 25 so that the winding end of the negative plate 25 is longer than the winding end 21e of the positive plate 21. The long first separator 31Z is cut by the first separator cutting unit 121 to cut out the first separator 31, and the long second separator 35Z is cut by the second separator cutting unit 123 to cut out the second separator 35 so that the winding end of the first separator 31 and the winding end of the second separator 35 are longer than the winding end of the negative plate 25.

Next, in a "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, since the width direction position Px of the long positive electrode plate 21Z has been adjusted in advance in the above-mentioned position adjustment step S114 in preparation for this remaining winding step S116, it is possible to suppress the occurrence of winding misalignment in the unwound portion 21f of the positive electrode plate 21 in the remaining winding step S116.
After the cylindrical wound electrode body 20Y has been 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).

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

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

Next, this wound electrode body 20 is wrapped in 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 together around the entire periphery to form the case 10.
Next, the electrolyte 3 is injected into the case 10 through the injection hole 16k, and the electrolyte 3 is impregnated into the wound electrode body 20. Thereafter, the injection hole 16k is covered from the outside with a sealing member 18, and the sealing member 18 is laser welded to the case 10. Thereafter, the battery 1 is subjected to initial charging, aging, various inspections, etc. In this manner, the battery 1 is completed.

As described above, in the manufacturing method of the wound electrode body 20, after the main winding process S111, in the position adjustment process S114 before the cutting process S115, the widthwise position Px of the long positive electrode plate 21Z is adjusted in advance based on the curvature W of the positive electrode plate 21 used in the winding process S11 so that the widthwise position Px of the unwound portion 21f of the positive electrode plate 21 becomes the reference widthwise position Ps in the remaining winding process S116. As a result, in the remaining winding process S116, the unwound portion 21f can be wound while the widthwise position Px of the unwound portion 21f of the positive electrode plate 21 is set to the reference widthwise position Ps, so that the winding deviation of the positive electrode plate 21 in the unwound portion 21f can be appropriately suppressed.

Furthermore, in this embodiment, the final 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 final winding step S111, so there is no need for a separate device or the like to perform the position adjustment step S114.
In addition, in this embodiment, for each positive electrode plate 21 used in the winding process S11, an estimated curvature amount Wn is used instead of an actually measured actual curvature amount Wr, so there is no need to obtain the actual measured curvature amount Wr of the positive electrode plate 21.

In this embodiment, the unwound length L of the long positive electrode plate 21Z from the positive electrode roll 21R is detected, and the amount of curvature W of the positive electrode plate 21 used in the winding process S11 is estimated based on this unwound length L, the amount of innermost curvature Wa of the innermost portion 21Za of the long positive electrode plate 21Z, and the amount of outermost curvature Wb of the outermost portion 21Zb of the long positive electrode plate 21Z. This allows the amount of curvature W of each positive electrode plate 21 to be appropriately estimated, and by performing the position adjustment process S114 using this estimated amount of curvature Wn, it is possible to more appropriately suppress winding misalignment of the positive electrode plate 21 that may occur in the remaining winding process S116.

In addition, in the manufacturing method of the battery 1, the electrode body manufacturing process S1 can form a wound electrode body 20 in which the winding misalignment of the positive electrode plate 21 in the unwound portion 21f is suppressed, so that the battery 1 can be manufactured with a wound electrode body 20 in which the winding misalignment of the positive electrode plate 21 in the unwound portion 21f is suppressed.

(Modifications)
Next, a variation of the above embodiment will be described (see FIG. 11). Note that the description of the same parts as 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 a position adjustment roll 141 whose inclination can be changed. In contrast, the position adjustment mechanism 240 of the winding device 200 according to the present modified embodiment differs in that the width direction position Px of the long positive electrode plate 21Z is adjusted by a position adjustment roll 241 that can move (slide) along the roll axis RX.

Specifically, as shown in FIG. 11, the position adjustment mechanism 240 of this modified embodiment has a position adjustment roll 241 configured to be movable along the roll axis RX. The position adjustment roll 241 is moved along the roll axis RX to adjust the widthwise position Px of the long positive electrode plate 21Z. By performing the position adjustment step S114 using this position adjustment mechanism 240, even in this modified embodiment, in the remaining winding step S116, the unwound portion 21f of the positive electrode plate 21 can be wound while the widthwise position Px of the unwound portion 21f is set to the reference widthwise position Ps. Therefore, the winding misalignment of the positive electrode plate 21 in the unwound portion 21f can be appropriately suppressed. Other parts similar to those of the embodiment have the same effects as those of the embodiment.

Although the present invention has been described above with reference to the embodiments and modified forms, it goes without saying that the present invention is not limited to the embodiments and modified forms, and can be appropriately modified and applied without departing from the spirit of the present invention.
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. This is because the current collector foil 26 (copper foil) of the negative electrode plate 25 is harder and less likely to deform than the current collector foil 22 (aluminum foil) of the positive electrode plate 21, and therefore the negative electrode plate 25 has a smaller amount of curvature W and the winding deviation in the remaining winding step S116 is also small. However, the position adjustment step S114 may be performed on the long negative electrode plate 25Z 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.

In the embodiment, the estimated curvature amount Wn of the positive electrode plate 21 is used as the curvature amount W of the positive electrode plate 21 used in the position adjustment process S114, but the actual measured curvature amount Wr of the positive electrode plate 21 can also be used. Specifically, multiple 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). Then, the actual measured curvature amount Wr can be obtained by detecting the edge position of the long positive electrode plate 21Z that is unwound from the positive electrode roll 21R of the positive electrode plate supply unit 104 and transported toward the position adjustment mechanism 140.

1 Battery (energy storage device)
20 Wound electrode body 20Y Cylindrical wound electrode body 21 Positive electrode plate (electrode plate)
21Z Long positive electrode plate (long electrode plate)
21Za: innermost circumferential portion (of a long positive electrode plate); 21Zb: outermost circumferential portion (of a long positive electrode plate); 21R: positive electrode roll (electrode roll)
21e: winding end 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 Unwound length detection process S113 Curvature estimation process S114 Position adjustment process S115 Cutting process S116 Remaining winding process S2 Device assembly process L Unwound length W Curvature amount Wa Innermost circumference curvature amount Wb Outermost circumference curvature amount Wn Estimated curvature amount Wr Actual curvature amount Px Width direction position Ps Reference width direction position

Claims (5)

A method for manufacturing a wound electrode assembly obtained by stacking and winding a first separator, a negative electrode plate, a second separator, and a positive electrode plate, each of which is in the shape of a strip, comprising the steps of:
a winding step of overlapping and winding the first separator, the negative electrode plate, the second separator, and the positive electrode plate around a winding core,
The winding process includes:
a main winding process for winding a long electrode plate before cutting into a plurality of electrode plates of either the positive electrode plate or the negative electrode plate while controlling a widthwise position of the long electrode plate so that a widthwise position of the long electrode plate during transportation is a reference widthwise position;
a cutting step of cutting the long electrode plate in a width direction at a winding end of the electrode plate to cut out the electrode plate;
a remaining winding step of winding up an unwound portion of the cut electrode plate,
The manufacturing method of a wound electrode body further includes a position adjustment process, after the main winding process and before the cutting process, for adjusting the widthwise position of the long electrode plate based on the amount of curvature of the electrode plate, instead of controlling the widthwise position in the main winding process, so that the widthwise position of the unwound portion in the remaining winding process becomes the reference widthwise position. A method for manufacturing a wound electrode assembly according to claim 1,
The main winding process includes:
a position adjustment mechanism for adjusting the width direction position of the long electrode plate,
The position adjustment step includes:
A method for manufacturing a wound electrode body using the position adjustment mechanism. A method for manufacturing a wound electrode assembly according to claim 1 or 2, comprising:
The position adjustment step includes:
A method for manufacturing a wound electrode body, comprising the steps of: adjusting the widthwise position of the long electrode plate by using an estimated amount of curvature of the electrode plate as the amount of curvature of the electrode plate. A method for manufacturing a wound electrode assembly according to claim 3,
The long electrode plate is
The long electrode plate is unwound from an electrode roll that has been previously wound into a roll.
The winding step includes:
a winding length detection step of detecting the unwound length of the long electrode plate from the beginning of unwinding of the electrode roll to the portion to be used in the winding step;
The detected unwinding length,
an innermost periphery curvature amount, which is an amount of curvature at an innermost periphery portion of the long electrode plate that is located at the innermost periphery of the electrode roll;
Based on an outermost periphery curvature amount, which is an amount of curvature at an outermost periphery portion of the long electrode plate that is located at the initial outermost periphery of the electrode roll,
and a curvature amount estimating step of estimating the curvature amount of the electrode plate used in the winding step to obtain the estimated curvature amount. A method for manufacturing an electricity 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 of which is in the form of a strip, comprising:
an electrode assembly manufacturing process for manufacturing the wound electrode assembly by the method for manufacturing the wound electrode assembly according to claim 1 or 2;
and a device assembling step of assembling the electricity storage device using the wound electrode body.

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