JP7701905B2 - 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 electricity 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 (edge) of the electrode plate being transported, 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 is 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 its width direction. If the electrode plate is curved, the greater the amount of curvature, the greater the winding misalignment of the electrode plate. Therefore, the position control of the electrode plate using the edge sensor and EPC described above may not be enough to suppress the winding misalignment of the electrode plate. In particular, if the conveying speed of the electrode plate is increased to improve productivity, the control cannot keep up, and the winding misalignment of the electrode plate cannot be suppressed.

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 misalignment of the electrode plate during the winding process, and a method for manufacturing an electricity storage device that includes the wound electrode assembly.

(1) One aspect of the present invention for solving the above problem is a manufacturing method for a wound electrode body 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, the manufacturing method including a winding step of stacking and winding the first separator, the negative electrode plate, the second separator, and the positive electrode plate around a winding core, the winding step detecting a width direction position of at least one of the electrode plates, the positive electrode plate and the negative electrode plate, during transport, and winding the electrode plate while controlling the width direction position of the electrode plate based on the detected width direction position and an estimated amount of curvature of the electrode plate, rather than an actual measured amount of curvature of the electrode body, so that the width direction position becomes a reference width direction position.

In the above-mentioned method for manufacturing a wound electrode body, in the winding step, the width direction position of the electrode plate is controlled based on the detected width direction position of the electrode plate and the estimated curvature amount of the electrode plate so that the width direction position becomes a reference width direction position, while the electrode plate is wound. Therefore, compared to the conventional case in which the width direction position of the electrode plate is controlled simply based on the detected width direction position without taking into account the curvature amount of the electrode plate, it is possible to appropriately suppress winding deviation of the electrode plate that may occur in the winding step.
In addition, it may be difficult to actually measure the amount of curvature of each electrode plate used in the winding process from the viewpoints of measurement accuracy and production costs. In contrast, in the above-mentioned manufacturing method, an estimated amount of curvature is used instead of an actual measured amount of curvature of the electrode body, so there is no need to obtain an actual measured amount of curvature of the electrode body.

The "width direction position" of the electrode plate refers to a specific position in the width direction of the electrode plate, such as one edge in the width direction, the center in the width direction, etc. Examples of a method for detecting the width direction position of the electrode plate include a method for detecting the width direction position of the electrode plate using a laser, and a method for detecting the width direction position of the electrode plate using a camera.
Examples of 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 include a method in which the position adjustment roll that transports the electrode plate is moved (slid) along the roll axis direction or the inclination of the position adjustment roll is changed to move the width direction position of the electrode plate and set the width direction position to the reference width direction position.

(2) Further, in the method for manufacturing the wound electrode body described in (1), the electrode plate is an electrode plate obtained by unwinding and cutting a long electrode plate from an electrode roll in which a long electrode plate has been wound in a roll shape in advance, and the winding process may include a winding length detection process for detecting the unwound length of the long electrode plate unwound from the beginning of unwinding the electrode roll to the part used in the winding process, and a curvature amount estimation process for estimating the curvature amount of the electrode plate used in the winding process based on the detected unwound length, an innermost curvature amount which is the curvature amount at the innermost part of the long electrode plate located at the innermost part of the electrode roll, and an outermost curvature amount which is the curvature amount at the outermost part of the long electrode plate located at the initial outermost part of the electrode roll, to obtain the estimated curvature amount.

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 to be 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 winding process using this estimated amount of curvature, it is possible to more appropriately suppress winding misalignment of the electrode plate.

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.

(3) Yet another aspect is a method for manufacturing an electric 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, the method comprising: an electrode body manufacturing process for manufacturing the wound electrode body by the wound electrode body manufacturing process described in (1) or (2); and a device assembly process for assembling the electric storage device using the wound electrode body.

The manufacturing method for the electricity storage device described above makes it possible to form a wound electrode body in which the winding misalignment of the electrode plate is suppressed during the electrode body manufacturing process, and therefore makes it possible to manufacture an electricity storage device equipped with a wound electrode body in which the winding misalignment of the electrode plate 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. 10A to 10C are explanatory diagrams illustrating adjustment of the width direction position of the 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 the 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 9).
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. 7 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. 8). 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. 8) 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 and FIG. 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.

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 positive electrode plate 21 (long positive electrode plate 21Z).
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. 6) of one end edge (edge) in the width direction EH of the positive electrode plate 21 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 positive electrode plate 21 while transporting the positive electrode plate 21 (see FIG. 6). 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 positive electrode plate 21 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 winding device 100 described above 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 unwound 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. For example, when a quarter of the long positive electrode plate 21Z is 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.

Subsequently, in a "curve amount estimation step S112" (see FIG. 4) of the winding step S11, the control unit 160 (see FIG. 5) estimates the curvature amount W of the positive electrode plate 21 used in the winding step S11 to obtain an estimated curvature amount Wn.
Specifically, prior to mounting the positive electrode roll 21R to the winding device 100, the innermost circumference curvature amount Wa, which is the curvature amount W of the innermost circumference portion 21Za (see FIG. 7) located at the innermost circumference of the positive electrode roll 21R, of the long positive electrode plate 21Z, and the outermost circumference curvature amount Wb, which is the curvature W of the outermost circumference portion 21Zb located at the initial outermost circumference 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 8), and the amount of curvature Wa at the innermost periphery is calculated by Wa = b/a. For example, when the amount of widthwise deviation b = 0.5 mm, the amount of curvature Wa at the innermost periphery is 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, the widthwise deviation b at the longitudinal length a=2000 mm of the start of unwinding of the long positive electrode plate 21Z is measured (see FIG. 8), 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 S112, 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. 9 ). 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 winding step S11, the width direction position Px of the positive electrode plate 21 during transport is detected, and the positive electrode plate 21 is wound while controlling the width direction position Px based on the detected width direction position Px and the estimated curvature amount Wn of the positive electrode plate 21 so that the width direction position Px of the positive electrode plate 21 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 estimated curvature amount Wn estimated by the control unit 160, the inclination of the position adjustment roll 141 is changed in the position adjustment mechanism 140 so that the width direction position Px becomes the reference width direction position Ps (see FIG. 6), and the width direction position Px of the positive electrode plate 21 is controlled (PID control).
For each parameter of the PID control, a preliminary experiment is performed in advance to obtain an appropriate value. By performing the winding step S11 in this manner, the positive electrode plate 21 can be wound around the winding core 111 together with the negative electrode plate 25 and the like while the width direction position Px of the positive electrode plate 21 is set to the reference width direction position Ps, so that the winding deviation of the positive electrode plate 21 can be appropriately suppressed.

At the end of the winding of the cylindrical wound electrode body 20Y, the positive plate cutting section 124 cuts the long positive plate 21Z to cut out the positive plate 21, and the negative plate cutting section 122 cuts the long negative plate 25Z to cut out the negative plate 25 so that the end of the winding of the negative plate 25 is longer than the end of the winding of the positive plate 21. Furthermore, the first separator cutting section 121 cuts the long first separator 31Z to cut out the first separator 31, and the second separator cutting section 123 cuts the long second separator 35Z to cut out the second separator 35 so that the end of the winding of the first separator 31 and the end of the second separator 35 are each longer than the end of the winding of the negative plate 25. After the cylindrically wound electrode body 20Y has been wound, the end of the first separator 31 located on the outermost periphery of the cylindrically wound electrode body 20Y is fixed to the cylindrically wound electrode body 20Y with adhesive tape (not shown).

Next, in the "pressing step S12" (see FIG. 4) of the electrode body manufacturing process S1, 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, in the winding process S11, the widthwise position Px of the positive electrode plate 21 is controlled so that the widthwise position Px becomes the reference widthwise position Ps based on the detected widthwise position Px of the positive electrode plate 21 and the estimated curvature Wn of the positive electrode plate 21. Therefore, compared to the conventional case in which the widthwise position Px of the positive electrode plate 21 is controlled simply based on the detected widthwise position Px without taking into account the curvature of the positive electrode plate 21, the winding deviation of the positive electrode plate 21 that may occur in the winding process S11 can be appropriately suppressed. In addition, for each positive electrode plate 21 used in the winding process S11, the estimated curvature Wn is used instead of the actual measured curvature, so there is no need to obtain the actual measured curvature of the positive electrode plate 21.

Furthermore, in this embodiment, the unwound length L of the long positive electrode plate 21Z from the positive electrode roll 21R is detected, and an estimated curvature Wr of the positive electrode plate 21 used in the winding process S11 is estimated based on this unwound length L, the innermost curvature Wa of the innermost portion 21Za of the long positive electrode plate 21Z, and the outermost curvature Wb of the outermost portion 21Zb of the long positive electrode plate 21Z. This allows the curvature W of each positive electrode plate 21 to be appropriately estimated, so that the winding misalignment of the positive electrode plate 21 can be more appropriately suppressed by performing the winding process S11 using this estimated curvature Wn.

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

(Modifications)
Next, a variation of the above embodiment will be described (see FIG. 10). 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 positive electrode plate 21 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 positive electrode plate 21 is adjusted by a position adjustment roll 241 that can move (slide) along the roll axis RX.

Specifically, as shown in FIG. 10, 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 positive electrode plate 21, and the widthwise position Px is set to the reference widthwise position Ps. This modified embodiment can also appropriately suppress winding misalignment of the positive electrode plate 21 that may occur in the winding process S11, compared to the conventional case in which the widthwise position Px of the positive electrode plate 21 is controlled simply based on the detected widthwise position Px without taking into account the amount of curvature W of the positive electrode plate 21. Other parts similar to those of the embodiment provide 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, in order to suppress the winding misalignment of the positive electrode plate 21 in the winding step S11, the present invention is applied only to the transportation of the positive electrode plate 21. 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 thus the winding misalignment in the winding step S11 is also small. However, in order to more appropriately suppress the winding misalignment of the negative electrode plate 25, the present invention may also be applied to the transportation of the negative electrode plate 25.

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)
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 Unwound length detection process S112 Curvature amount estimation 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 Px Width direction position Ps Reference width direction position

Claims (3)

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:
Detecting a width direction position of at least one of the positive electrode plate and the negative electrode plate during transportation;
A manufacturing method for a wound electrode body in which the electrode plate is wound 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 an estimated amount of curvature of the electrode plate, rather than an actual measured amount of curvature of the electrode body. A method for manufacturing a wound electrode assembly according to claim 1,
The electrode plate is
The long electrode plate is obtained by unwinding and cutting a long electrode plate from an electrode roll in which the long electrode plate has been wound in advance into a roll shape,
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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