Electrode sheet manufacturing method and manufacturing device

Abstract

To make a thickness of an active material of an electrode sheet to be an intended thickness from an initial step of each lot.SOLUTION: In a press step, a thickness of an active material layer after press is measured, and a press condition is feed-back controlled on the basis of the thickness of the measured active material layer. In a setting step S60, an initial press condition is set for each lot. In an estimation step S60A of the setting step S60, on the basis of a pre-calculated correlation among the initial press condition, the press condition, and the thickness of the active material layer, the thickness of the active material layer in a preceding lot is estimated. In a correction value calculation step S60B, a difference E between a thickness B of the active material layer in the preceding lot and a thickness of the active material layer in the preceding lot estimated in the estimation step S60A is calculated, and a correction value V of the initial press condition for correcting the difference E is calculated on the basis of the correlation. In the correction step S60D, the correction value V is added to an initial press condition F before the correction, and an initial press condition G1 is calculated.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for manufacturing an electrode sheet for an electricity storage device. [Background technology]

[0002] For example, Patent Document 1 discloses a press roll device that continuously passes a metal web for a secondary battery electrode between upper and lower press rolls to press it. The press roll device described in Patent Document 1 is equipped with an in-line film thickness meter that continuously measures the thickness of the web and is configured to increase the bending pressure by a predetermined amount each time a predetermined decrease in the thickness of the web is confirmed. The bending pressure is a pressure applied in the opposite direction to the pressing pressure and is used to suppress curvature of the upper and lower press rolls. According to Patent Document 1, increasing the bending pressure widens the gap between the upper and lower press rolls. Patent Document 1 also states that increasing the bending pressure can suppress the gradual narrowing of the gap between the upper and lower press rolls due to thermal expansion and deformation of the press rolls, thereby suppressing the gradual thinning of the web thickness.

[0003] Furthermore, for example, Patent Document 2 discloses a press device having a pair of press rolls, a pair of housings supporting the pair of press rolls, and a wedge for adjusting the gap between the pair of housings. The press device described in Patent Document 2 is equipped with a temperature sensor for detecting the temperature of the pair of press rolls, etc. According to the method described in Patent Document 2, information on the basis weight (weight per unit area) of the active material layer formed on the current collector foil is acquired, and the position of the wedge is set based on a predetermined relationship between the basis weight, the position of the wedge, and the thickness of the active material layer. Since the wedge position determined in this way is for a reference temperature, the method described in Patent Document 2 determines an appropriate gap between the pair of press rolls based on the temperature detected by the temperature sensor. During the pressing process, the gap between the pair of press rolls is corrected according to the temperature of the pair of press rolls, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-175501 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-91649 Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Documents 1 and 2, the thickness of the active material layer of an electrode sheet after pressing varies depending on factors such as the temperature of the press rolls of a roll press. As described in Patent Document 1, it is believed that the thickness of the active material layer can be kept within a desired range by feedback-controlling the gap between the press rolls based on the measured thickness of the active material layer. However, even with such control, sufficient feedback is not provided at the beginning of each lot of electrode sheets, and therefore many portions of the initial end of the electrode sheet where the thickness of the active material layer does not fall within the target range are likely to occur.

[0006] Here, we propose a manufacturing method for an electrode sheet that makes it easy to achieve a target thickness for the active material layer from the initial stage of the lot, and also propose an electrode sheet manufacturing device that makes it easy to achieve a target thickness for the active material layer from the initial stage of the lot. [Means for solving the problem]

[0007] The electrode sheet manufacturing method disclosed herein is a manufacturing method for an electrode sheet including a strip-shaped electrode foil and an active material layer formed on the electrode foil, and includes a pressing step of continuously pressing the electrode sheet for each lot using a pair of opposing press rolls of a roll press, and a setting step of setting initial pressing conditions of the roll press for each lot. In the pressing step, the thickness of the active material layer after pressing is measured, and the pressing conditions of the roll press are feedback-controlled based on the measured thickness of the active material layer. The setting step includes an estimation step, a correction value calculation step, and a correction step. In the estimation step, the thickness of the active material layer of the immediately preceding lot is estimated from the initial pressing conditions of the immediately preceding lot and the feedback-controlled pressing conditions of the immediately preceding lot based on the initial pressing conditions and a predetermined correlation between the pressing conditions and the thickness of the active material layer. In the correction value calculation step, a difference between the thickness of the active material layer of the immediately preceding lot and the thickness of the active material layer of the immediately preceding lot estimated in the estimation step is calculated, and a correction value for the initial pressing conditions that corrects the difference is calculated based on the correlation. In the correction step, the correction value is added to the initial pressing conditions before correction to determine the initial pressing conditions.

[0008] In the above method, the difference between the thickness of the active material layer of the immediately preceding lot and the thickness of the active material layer of the immediately preceding lot estimated in the estimation step is mainly due to the influence of uncontrolled factors, such as temperature. According to the above electrode sheet manufacturing method, a correction value is calculated to correct for the influence of uncontrolled factors in the immediately preceding lot, and the initial pressing conditions are corrected using this correction value. Therefore, the active material layer thickness of each electrode sheet lot is likely to reach the target thickness from the initial stage.

[0009] The electrode sheet manufacturing apparatus disclosed herein includes a roll press machine having a pair of opposing press rolls, which continuously presses an electrode sheet, each lot comprising a strip-shaped electrode foil and an active material layer formed on the electrode foil, with the pair of press rolls. The roll press machine includes a measuring device for measuring the thickness of the active material layer after pressing, a press control unit for feedback-controlling the pressing conditions based on the thickness of the active material layer measured by the measuring device, and a setting unit for setting initial pressing conditions for each lot. The setting unit includes a memory unit, an estimating unit, a correction value calculating unit, and a correcting unit. The memory unit stores the initial pressing conditions and a predetermined correlation between the pressing conditions and the thickness of the active material layer. The estimating unit estimates the thickness of the active material layer of the immediately preceding lot based on the correlation and the initial pressing conditions of the immediately preceding lot and the feedback-controlled pressing conditions of the immediately preceding lot. The correction value calculation unit calculates a difference between the thickness of the active material layer of the immediately preceding lot measured by the measurement device and the thickness of the active material layer of the immediately preceding lot estimated by the estimation unit, and calculates a correction value for the initial pressing conditions based on the correlation so as to correct the difference. The correction unit determines the initial pressing conditions by adding the correction value to the initial pressing conditions before correction.

[0010] The above device can also achieve the same effects as the above method. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic diagram of an electrode sheet manufacturing device. [Figure 2] FIG. 1 is a schematic side view of a roll press machine. [Figure 3] FIG. 2 is a schematic front view of a press device. [Figure 4] 10 is a graph showing a first correlation. [Figure 5] 10 is a graph showing a second correlation. [Figure 6] FIG. 1 is a process diagram for manufacturing an electrode sheet. [Figure 7]FIG. 10 is a process diagram of a basis weight obtaining process and a setting process. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, one embodiment of an apparatus for manufacturing an electrode sheet for an electricity storage device and a method for manufacturing an electrode sheet for an electricity storage device will be described. Note that the embodiment described here is, of course, not intended to particularly limit the present invention. Furthermore, each figure is a schematic diagram and does not necessarily faithfully reflect an actual product.

[0013] [Configuration of electrode sheet manufacturing equipment] FIG. 1 is a schematic diagram of an electrode sheet manufacturing apparatus 10 according to one embodiment. In this embodiment, the electrode sheet manufacturing apparatus 10 manufactures an electrode sheet 1 (see FIG. 2) for a lithium-ion secondary battery. However, the electrode sheet is not limited to the electrode sheet 1 for a lithium-ion secondary battery, and may be an electrode sheet for various known electricity storage devices. The term "electricity storage device" refers to any device that can extract electrical energy, and includes so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors (physical batteries) such as electric double layer capacitors.

[0014] The electrode sheet 1 includes a strip-shaped electrode foil 2 and an active material layer 3 formed on the electrode foil 2. The positive electrode sheet is a member in which a positive electrode active material layer 3 containing a positive electrode active material is formed on the surface of a strip-shaped electrode foil 2 (e.g., aluminum foil) of a predetermined width and thickness. In a lithium-ion secondary battery, the positive electrode active material is, for example, a material that can release lithium ions during charging and absorb lithium ions during discharging, such as a lithium transition metal composite material. The negative electrode sheet is a member in which a negative electrode active material layer 3 containing a negative electrode active material is formed on the surface of a strip-shaped electrode foil 2 (e.g., copper foil) of a predetermined width and thickness. In a lithium-ion secondary battery, the negative electrode active material is, for example, a material that can absorb lithium ions during charging and release the absorbed lithium ions during discharging, such as natural graphite. The positive electrode active material and the negative electrode active material are not particularly limited, and various materials other than those described above have been proposed.

[0015] As shown in FIG. 1, the electrode sheet manufacturing apparatus 10 includes a measuring device 20, a kneading device 30, a coating device 40, a drying device 50, and a roll press machine 60.

[0016] The weighing device 20 weighs the raw materials for the active material layer 3. The weighed raw materials for the active material layer 3 are mixed and kneaded by the kneading device 30. The raw materials for the active material layer 3, which have been kneaded to form a slurry, are then coated onto the electrode foil 2 by the coating device 40. The coating device 40 is configured to be able to determine the amount of raw materials for the active material layer 3 coated onto the electrode foil 2 for each lot of the electrode sheet 1. The coating device 40 determines the amount of raw materials for the coated active material layer 3 from, for example, the difference between the remaining weight of the raw materials before and after coating. The coating device 40 is an example of a basis weight acquisition device that acquires the basis weight of the active material layer 3 for each lot. The basis weight of the active material layer 3 is the weight per area of ​​the active material layer 3.

[0017] The drying device 50 dries the applied raw material of the active material layer 3 in a slurry state. A basis weight acquisition device that acquires the basis weight of the active material layer 3 for each lot may be provided in the drying device 50. The roll press machine 60 continuously presses the electrode sheet 1 for each lot to adjust the thickness of the active material layer 3 to within a predetermined range.

[0018] FIG. 2 is a schematic side view of a roll press machine 60. As shown in FIG. 2, the roll press machine 60 according to this embodiment includes an unwinding device 60A, a pressing device 60B, and a winding device 60C. The electrode sheet 1 on which the active material layer 3 has been dried is supplied to the unwinding device 60A in the form of a roll. The winding device 60C winds up the electrode sheet 1 that has been unwound from the unwinding device 60A and pressed by the pressing device 60B. The roll press machine 60 includes a control device 70 that controls the operations of the unwinding device 60A, the pressing device 60B, and the winding device 60C.

[0019] Fig. 3 is a schematic front view of press device 60B. As shown in Fig. 3, press device 60B includes a pair of press rolls 61, 62 facing each other in the thickness direction (here, the vertical direction) of electrode sheet 1, a pair of housings 63, 64 supporting the pair of press rolls 61, 62 so that they can move toward or away from each other, a gap setting mechanism 65 sandwiched between the pair of housings 63, 64, a drive device 66 moving the pair of housings 63, 64 toward or away from each other, a load cell 67 measuring the press load, an in-line film thickness meter 68 measuring the thickness of active material layer 3 after pressing, and a rotation device 69 rotating the pair of press rolls 61, 62.

[0020] The roll press machine 60 continuously presses the electrode sheet 1 for each lot using a pair of press rolls 61 and 62. The drive device 66 is configured to move the lower housing 64 vertically. The drive device 66 moves the lower roll 62 vertically via the lower housing 64, thereby moving the pair of press rolls 61 and 62 toward and away from each other. The drive device 66 includes a lifting wedge 66a that supports the lower housing 64. The drive device 66 moves the lower housing 64 vertically by horizontally shifting the pair of upper and lower lifting wedges 66a, whose hypotenuses are in contact with each other. The load cell 67 measures the load applied to the lower housing 64 by driving the drive device 66, i.e., the press load of the roll press machine 60. The rotation device 69 is configured to rotate the pair of press rolls 61 and 62 to feed the electrode sheet 1 toward the winding device 60C. The rotating device 69 may be configured to rotate only one of the pair of press rolls 61, 62.

[0021] The gap setting mechanism 65 is a mechanism for setting the gap Gr between the pair of press rolls 61, 62. The gap setting mechanism 65 is sandwiched between the pair of housings 63, 64 and includes a pair of upper and lower gap setting wedges 65a configured to be variable in length in the direction in which the pair of housings 63, 64 approach and separate (here, the vertical direction). The gap setting wedges 65a are an example of a gap setting member that can set the gap Gr between the pair of press rolls 61, 62. The pair of upper and lower gap setting wedges 65a are in contact with each other at their hypotenuses. The gap setting mechanism 65 includes a drive unit (not shown) that shifts the pair of gap setting wedges 65a horizontally. The gap setting mechanism 65 changes the vertical length of the gap setting wedges 65a by shifting the pair of gap setting wedges 65a horizontally. The gap setting wedges 65a adjust the gap between the pair of housings 63, 64, thereby setting the gap Gr between the pair of press rolls 61, 62. The gap Gr between the pair of press rolls 61, 62, which is set by the gap setting mechanism 65, is one of the initial press conditions that is set before the start of pressing. In this embodiment, the gap Gr between the press rolls 61, 62 cannot be changed during pressing.

[0022] As shown in FIG. 2 , the control device 70 includes a press control unit 71 and a setting unit 72. The press control unit 71 feedback-controls the pressing conditions of the roll press machine 60 based on the thickness of the active material layer 3 measured by the in-line film thickness meter 68. In this embodiment, the press load (measured by the load cell 67) of the roll press machine 60 is feedback-controlled based on the thickness of the active material layer 3 measured by the in-line film thickness meter 68. Here, the pressing condition feedback-controlled by the press control unit 71 is the press load. The gap Gr between the pair of press rolls 61, 62, which is determined by the setting of the gap setting mechanism 65, cannot be changed during pressing. However, the gap setting wedge 65 a elastically deforms in response to the press load of the drive unit 66, which is feedback-controlled by the press control unit 71. This makes it possible to control the thickness of the active material layer 3 to approach a target thickness based on the thickness of the active material layer 3 measured by the in-line film thickness meter 68.

[0023] The setting unit 72 sets initial press conditions for each lot according to the basis weight of the active material layer 3 acquired by the basis weight acquisition device (here, the coating device 40). The initial press conditions include the gap Gr between the pair of press rolls 61, 62. In this embodiment, the press load in the initial press conditions is determined regardless of the basis weight.

[0024] As shown in FIG. 2, the setting unit 72 includes a storage unit 72A, an estimation unit 72B, a pre-correction condition calculation unit 72C, a correction value calculation unit 72D, a correction unit 72E, and an idle operation control unit 72F.

[0025] The memory unit 72A stores a correlation (hereinafter also referred to as a first correlation) between the initial pressing conditions and the thickness of the active material layer 3, which is determined in advance for each basis weight of the active material layer 3, and a correlation (hereinafter also referred to as a second correlation) between the amount of change in the pressing conditions and the amount of change in the thickness of the active material layer 3. Fig. 4 is a graph showing the first correlation. Fig. 5 is a graph showing the second correlation.

[0026] As shown in FIG. 4, a first correlation between the initial pressing conditions (the gap Gr between the press rolls 61 and 62) and the thickness of the active material layer 3 is obtained by measuring the thickness of the active material layer 3 of samples of electrode sheet 1 pressed with different gaps Gr. The ambient temperature and the temperature of the press rolls 61 and 62 during pressing are predetermined temperatures in the room temperature range. The press load is the press load under the initial pressing conditions. Here, the correlation is determined for three types of samples with different basis weights of the active material layer 3. The sample represented by graph GF1 in FIG. 4 is an upper limit sample in which the active material layer 3 is formed so as to have the upper limit of the basis weight. The sample represented by graph GF2 in FIG. 4 is a lower limit sample in which the active material layer 3 is formed so as to have the lower limit of the basis weight. The sample represented by graph GF3 in FIG. 4 is a center sample in which the active material layer 3 is formed so as to have the median value of the basis weight.

[0027] As shown in FIG. 4, all three graphs GF1 to GF3 show that the thickness of the active material layer 3 increases as the gap Gr increases. Furthermore, the three graphs GF1 to GF3 also show that the thickness of the active material layer 3 increases as the basis weight increases (the active material layer 3 recovers more even when pressed under the same pressing conditions). For example, linear interpolation is performed between graphs GF1 and GF3 and between graphs GF2 and GF3. Note that if the influence of the basis weight of the active material layer 3 is not taken into consideration, the first correlation does not need to be calculated for each basis weight.

[0028] A second correlation between the change in press conditions (press load) and the change in thickness of the active material layer 3, as shown in FIG. 5, is obtained by measuring the thickness of the active material layer 3 of samples of electrode sheet 1 pressed while changing the press load. The pressing environment, including the temperature of the press rolls 61 and 62, is the same as when the graph in FIG. 4 was obtained. The gap Gr between the press rolls 61 and 62 and the basis weight of the active material layer 3 are not particularly limited, as long as they do not significantly deviate from the gap Gr and basis weight expected during production. In FIG. 5, the slope of graph GF4 is referenced. The gap Gr between the press rolls 61 and 62 and the basis weight of the active material layer 3 do not significantly affect the ratio of the change in press load to the change in thickness of the active material layer 3, i.e., the slope of graph GF4.

[0029] Based on the first and second correlations described above, estimation unit 72B estimates the thickness of active material layer 3 of the immediately preceding lot from the basis weight of active material layer 3 of the immediately preceding lot, the initial press conditions of the immediately preceding lot (here, the distance Gr between press rolls 61 and 62), and the feedback-controlled press conditions of the immediately preceding lot (here, the press load). The estimated thickness of active material layer 3 is the thickness of active material layer 3 expected under the environmental conditions (including at least the ambient temperature and the temperatures of press rolls 61 and 62 being predetermined temperatures) when FIGS. 4 and 5 were obtained. Estimation unit 72B estimates the thickness of active material layer 3 using the feedback-controlled press conditions (press load) at the end portion of electrode sheet 1 of the immediately preceding lot. Details of the method for estimating the thickness of active material layer 3 of the immediately preceding lot will be described later.

[0030] The pre-correction condition calculation unit 72C obtains the pre-correction initial press conditions (here, the gap Gr between the press rolls 61, 62) based on the first correlation and in accordance with the basis weight acquired by the basis weight acquisition device (coating device 40). The acquired basis weight and the obtained gap Gr relate to the electrode sheet 1 that will be pressed. The method for obtaining the gap Gr before correction will be described in detail later.

[0031] Correction value calculation unit 72D calculates the difference between the thickness of active material layer 3 of the immediately preceding lot measured by in-line film thickness meter 68 and the thickness of active material layer 3 of the immediately preceding lot estimated by estimation unit 72B, and calculates a correction value for the initial press condition (the gap Gr between press rolls 61, 62) that corrects for the difference, based on the first correlation. The method for calculating the correction value will be described in detail later. Here, correction value calculation unit 72D calculates the correction value using the thickness of active material layer 3 measured at the end portion of electrode sheet 1 of the immediately preceding lot.

[0032] The correction unit 72E determines the initial press conditions by adding the correction value to the initial press conditions before correction. The setting unit 72 matches the initial press conditions of the roll press machine 60 to the initial press conditions determined by the correction unit 72E. Specifically, the setting unit 72 matches the gap Gr between the pair of press rolls 61, 62 to the initial press conditions by adjusting the length of the gap setting wedge 65a.

[0033] The idle operation control unit 72F idles the roll press machine 60 when the electrode sheet 1 has not been pressed for a predetermined time or longer. Idle operation maintains the state of the roll press machine 60 and prevents the difference in state between the next lot and the immediately preceding lot from widening. During idle operation, the rotation device 69 is controlled to rotate the pair of press rolls 61, 62 without the electrode sheet 1 being supplied. This generates heat in the sliding portions (e.g., bearings) of the press rolls 61, 62, preventing a decrease in the temperature of the press rolls 61, 62. However, idle operation is not limited to the above. During idle operation, for example, the pair of press rolls 61, 62 may be rotated with a dummy sheet sandwiched between them. The dummy sheet may be preferably made of, for example, soft resin or rubber so as not to damage the pair of press rolls 61, 62.

[0034] [Electrode sheet manufacturing process] The manufacturing process of the electrode sheet 1 using the electrode sheet manufacturing apparatus 10 according to this embodiment will be described below. FIG. 6 is a process diagram of the manufacturing of the electrode sheet 1 using the electrode sheet manufacturing apparatus 10. As shown in FIG. 6, the manufacturing process of the electrode sheet 1 includes a measuring step S10, a kneading step S20, a coating step S30, a drying step S40, a basis weight acquisition step S50, a setting step S60 of initial pressing conditions, and a pressing step S70. Note that the manufacturing process of the electrode sheet 1 shown in FIG. 6 is merely an example. The manufacturing process of the electrode sheet 1 may include other steps, for example, or some steps may be omitted.

[0035] Details of the measuring step S10 to the drying step S40 will be omitted. In the basis weight obtaining step S50, the basis weight of the active material layer 3 is obtained for each lot of the electrode sheet 1. The basis weight obtaining step S50 is performed before the pressing step S70. Note that if the influence of the basis weight of the active material layer 3 is not taken into consideration, the basis weight obtaining step S50 does not have to be performed.

[0036] In the pressing step S70, the electrode sheet 1 is continuously pressed for each lot by a pair of opposing press rolls 61, 62 of a roll press machine 60. In the pressing step S70, the thickness of the active material layer 3 after pressing is measured by an in-line film thickness meter 68, and the pressing conditions of the roll press machine 60 (here, the press load) are feedback-controlled based on the measured thickness of the active material layer 3.

[0037] In the setting step S60, the initial pressing conditions of the roll press machine 60, in this case the distance Gr between the press rolls 61 and 62, are set for each lot according to the basis weight of the active material layer 3 acquired in the basis weight acquisition step S50. The initial pressing conditions set in the setting step S60 reflect the results of the immediately preceding lot. FIG. 7 is a more detailed process diagram of the basis weight acquisition step S50 and the setting step S60. As shown in FIG. 7, the setting step S60 includes steps S61 to S68.

[0038] 7, in step S61, the thickness of the active material layer 3 is calculated based on the first correlation from the basis weight of the active material layer 3 of the immediately preceding lot and the initial press conditions of the immediately preceding lot (here, the gap Gr between the pair of press rolls 61, 62). As shown in FIG. 4, for example, if the set value of the gap Gr of the immediately preceding lot is G0 and the basis weight is at the upper limit (corresponding to graph GF1), the thickness of the active material layer 3 based on the first correlation is calculated to be A. Thickness A is the estimated thickness of the active material layer 3 of the immediately preceding lot, assuming that the environment is the same as when the graphs of FIGS. 4 and 5 were obtained, and that the press load is maintained at the initial press conditions.

[0039] In step S62, the thickness of the active material layer 3 at the end of pressing the immediately preceding lot is obtained. This thickness of the active material layer 3 is the thickness of the active material layer 3 at the end portion of the electrode sheet 1 of the immediately preceding lot, measured by the in-line film thickness meter 68 during the pressing process of the immediately preceding lot. In other words, it is the thickness of the immediately preceding active material layer 3 among the immediately preceding lots. Hereinafter, the thickness of the active material layer 3 obtained in step S62 is referred to as B.

[0040] In step S63, the difference between the thickness A of the active material layer 3 estimated based on the first correlation and the thickness (actual thickness) B of the active material layer 3 obtained in step S62 is calculated. That is, the difference C=AB is calculated. The difference C is caused by the influence of the environment in the immediately preceding lot and the influence of feedback control of the press load (change in the press load from the initial press conditions).

[0041] In step S64, the amount of change in thickness of active material layer 3 due to feedback control of the press load is estimated based on the second correlation between the amount of change in press load and the amount of change in thickness of active material layer 3. As shown in Fig. 5, if the press load P1 has increased by ΔP compared to the press load P0 of the initial press conditions when the pressing step S70 of the immediately preceding lot is completed, it is estimated that the thickness of active material layer 3 at the end of the immediately preceding lot has decreased by D due to the increase in press load.

[0042] In step S65, the change D, which indicates the influence of the change in press load, is subtracted from the thickness difference C of the active material layer 3 calculated in step S63 (which indicates the influence of the environment and the influence of the change in press load). That is, the calculation E=CD is performed. E is the difference from the estimated value of the thickness of the active material layer 3 in the immediately previous lot, which was caused by the influence of the environment.

[0043] In step S66, the pre-correction initial pressing conditions (the gap Gr between the press rolls 61, 62) are determined based on the first correlation and the basis weight acquired in the basis weight acquisition step S50. For example, if the basis weight of the lot to be subjected to the pressing step S70 is at the lower limit (corresponding to graph GF2) and the target thickness of the active material layer 3 is T1, the pre-correction gap Gr between the press rolls 61, 62 is temporarily set to the pre-correction gap F, as shown in FIG. 4. Note that if the influence of the basis weight of the active material layer 3 is not taken into consideration, the pre-correction initial pressing conditions may be determined in advance. In that case, step S66 may be omitted.

[0044] In step S67, a correction value V for the initial press conditions is calculated based on the first correlation to correct the difference E in thickness of the active material layer 3 due to environmental factors. That is, as shown in Fig. 4, the difference E is converted into a correction value V for the gap Gr between the press rolls 61, 62 based on the first correlation. As shown in Fig. 4, the graphs GF1 to GF3 are generally parallel (have roughly the same slope), and therefore the correction value V hardly varies depending on the basis weight of the active material layer 3.

[0045] In step S68, the correction value V is added to the gap F between the press rolls 61 and 62 before correction obtained in step S66, and the gap G1 between the press rolls 61 and 62 after correction is calculated as G1 = F + V. This gap G1 becomes the initial press condition for the next lot.

[0046] The order of steps S61 to S68 can be changed as appropriate. Steps S61 and S64 correspond to estimation step S60A, which estimates the thickness of the active material layer 3 of the immediately preceding lot (corresponding to estimated thickness A - estimated change D) from the basis weight of the active material layer 3 of the immediately preceding lot, the initial press conditions of the immediately preceding lot, and the feedback-controlled press conditions of the immediately preceding lot based on the first correlation and the second correlation. Estimation step S60A may be performed discontinuously, as in the example shown in FIG. 7, or may be performed continuously. Note that when the influence of the basis weight of the active material layer 3 is not taken into consideration, the estimated thickness of the active material layer 3 of the immediately preceding lot may be determined regardless of the basis weight.

[0047] Steps S62, S63, S65, and S67 correspond to a correction value calculation step S60B in which a difference E (=ADB) between the thickness B of the active material layer 3 of the immediately preceding lot and the thickness (AD) of the active material layer 3 of the immediately preceding lot estimated in the estimation step S60A is calculated, and a correction value V of the initial pressing conditions is calculated based on the first correlation to correct the difference E. The correction value calculation step S60B may be performed discontinuously as in the example shown in FIG. 7, or may be performed continuously.

[0048] Step S66 corresponds to a pre-correction condition calculation step S60C in which pre-correction initial press conditions F are calculated based on the first correlation and in accordance with the basis weight acquired in the basis weight acquisition step S50. Step S68 corresponds to a correction step S60D in which pre-correction initial press conditions G1 are calculated by adding a correction value V to the pre-correction initial press conditions F. The pre-correction condition calculation step S60C may be performed at any time before the correction step S60D.

[0049] [Effects of the embodiment] The following describes the effects that can be achieved by the method for manufacturing the electrode sheet 1 according to this embodiment. Note that the configuration of the electrode sheet manufacturing apparatus 10 for realizing the method described below also achieves the same effects.

[0050] The method for manufacturing an electrode sheet 1 according to this embodiment is a method for manufacturing an electrode sheet 1 including a strip-shaped electrode foil 2 and an active material layer 3 formed on the electrode foil 2, and includes a pressing step S70 in which the electrode sheet 1 is continuously pressed for each lot using a pair of opposing press rolls 61, 62 of a roll press machine 60, and a setting step S60 in which initial pressing conditions for the roll press machine 60 are set for each lot. In the pressing step S70, the thickness of the active material layer 3 after pressing is measured, and the pressing conditions for the roll press machine 60 are feedback-controlled based on the measured thickness of the active material layer 3.

[0051] The setting step S60 includes an estimation step S60A (steps S61 and S64), a correction value calculation step S60B (steps S62, S63, S65, and S67), and a correction step S60D (step S68). In the estimation step S60A, the thickness of the active material layer 3 of the immediately preceding lot is estimated from the initial press conditions of the immediately preceding lot and the feedback-controlled press conditions of the immediately preceding lot based on the initial press conditions and the correlations (here, the first and second correlations) between the press conditions and the thickness of the active material layer 3. In the correction value calculation step S60B, a difference E between the thickness B of the active material layer 3 of the immediately preceding lot and the thickness (AD) of the active material layer 3 of the immediately preceding lot estimated in the estimation step S60A is calculated, and a correction value V for the initial press conditions that corrects the difference E is calculated based on the correlations. In the correction step S60D, the correction value V is added to the initial press condition F before correction to obtain the initial press condition G1.

[0052] In the above method, the difference E between the thickness B of the active material layer 3 of the immediately preceding lot and the thickness (AD) of the active material layer 3 of the immediately preceding lot estimated in estimation step S60A is mainly due to the influence of uncontrolled factors, such as temperature. According to the method of this embodiment, a correction value V is calculated to correct for the influence of uncontrolled factors in the immediately preceding lot, and the initial pressing conditions are corrected using this correction value V. As a result, the thickness of the active material layer 3 tends to be the target thickness from the early stages of each lot of electrode sheet 1. In conventional methods that do not perform such correction, sufficient feedback of the pressing conditions is not possible at the early stages of each lot of electrode sheet 1. As a result, many portions of the initial end of the electrode sheet 1 where the thickness of the active material layer 3 does not fall within the target range are likely to occur.

[0053] In a typical conventional method, adjustment of the initial pressing conditions (e.g., the distance between press rolls) and measurement of the thickness of the active material layer (measured by cutting out a portion of the electrode sheet) are repeated to determine the optimal initial pressing conditions for each lot before starting the process. However, such a method results in a loss of time and a large amount of electrode sheet waste due to cutting out the electrode sheet for measuring the thickness of the active material layer.

[0054] In this embodiment, the manufacturing method of the electrode sheet 1 further includes a basis weight acquisition step S50 for acquiring the basis weight of the active material layer 3 for each lot of the electrode sheet 1. The correlations between the initial pressing conditions and the thickness of the active material layer 3 include a first correlation and a second correlation. The first correlation is a correlation between the initial pressing conditions and the thickness of the active material layer 3, which is determined in advance for each basis weight of the active material layer 3. The second correlation is a correlation between the amount of change in the pressing conditions and the amount of change in the thickness of the active material layer 3, which is determined in advance. The setting step S60 includes a pre-correction condition calculation step S60C (step S66). In the pre-correction condition calculation step S60C, pre-correction initial pressing conditions F are calculated based on the first correlation and in accordance with the basis weight acquired in the basis weight acquisition step S50. In the estimation step S60A, the thickness of the active material layer 3 of the immediately preceding lot is estimated based on the first correlation and the second correlation. In the correction value calculation step S60B, a correction value V is calculated based on the first correlation. This method makes it possible to obtain the initial pressing conditions G1 that also take into consideration the influence of the basis weight of the active material layer 3. The thickness of the active material layer 3 after pressing also changes depending on the basis weight of the active material layer 3.

[0055] In this embodiment, the feedback-controlled pressing conditions used in the estimation step S60A are the pressing conditions at the end portion of the electrode sheet 1 of the immediately preceding lot. The thickness of the active material layer 3 of the immediately preceding lot used in the correction value calculation step S60B is the thickness B of the active material layer 3 at the end portion of the electrode sheet 1 of the immediately preceding lot, measured in the pressing step S70. The environment to which the lot about to undergo the pressing step S70 is exposed is considered to be continuous with and similar to the environment to which the end portion of the immediately preceding lot was exposed. Therefore, this method allows for a more reliable correction value V to be obtained.

[0056] In this embodiment, the initial press conditions include the distance Gr between the pair of press rolls 61, 62. The press condition that is feedback-controlled is the press load. According to this method, by correcting the distance Gr between the pair of press rolls 61, 62 as an initial press condition, the thickness of the active material layer 3 can be made close to the target thickness from the initial stage of each lot of electrode sheet 1. Therefore, it is possible to quickly make the thickness of the active material layer 3 the target thickness by subsequent feedback control of the press load.

[0057] In this embodiment, the roll press machine 60 includes a pair of housings 63, 64 that support a pair of press rolls 61, 62 so that they can move toward or away from each other; a drive unit 66 that moves the pair of housings 63, 64 toward or away from each other; and a gap setting wedge 65a that is sandwiched between the pair of housings 63, 64 and whose length in the direction of movement of the pair of housings 63, 64 is variable. The gap setting wedge 65a is an example of a gap setting member that can set the gap Gr between the pair of press rolls 61, 62 by adjusting the gap between the pair of housings 63, 64. The setting step S60 includes adjusting the length of the gap setting wedge 65a to match the gap Gr between the pair of press rolls 61, 62 with the initial press condition G1. In the pressing step S70, the gap Gr between the pair of press rolls 61, 62 changes as the gap setting wedge 65a elastically deforms in response to the press load of the drive unit 66 that is feedback-controlled. According to this method, the gap Gr between the press rolls 61, 62, which is an initial pressing condition, can be changed by the press load that is feedback controlled, and the thickness of the active material layer 3 can be changed.

[0058] [Other embodiments] The above describes one embodiment of the electrode sheet manufacturing apparatus and manufacturing method proposed herein. However, the above embodiment is merely an example, and other aspects may be employed. For example, in the above embodiment, the initial press condition of the roll press machine 60 is the distance Gr between the pair of press rolls 61 and 62, and the feedback-controlled press condition is the press load. However, the initial press condition and the feedback-controlled press condition of the roll press machine 60 are not limited to this. For example, the initial press condition and the feedback-controlled press condition of the roll press machine may both be the distance between the press rolls.

[0059] In the above case, the second correlation between the amount of change in the pressing conditions and the amount of change in the thickness of the active material layer may be the same as the first correlation between the initial pressing conditions and the thickness of the active material layer. In this case, the change in the press roll gap as the initial pressing condition and the change in the press roll gap as the feedback-controlled pressing condition will yield similar results. In comparison with the process shown in FIG. 7, for example, the step corresponding to step S64 may be different from that shown in FIG. 7. In this case, in the step corresponding to step S64, the amount of change in the thickness of the active material layer due to feedback control may be estimated based on the first correlation shown in FIG. 4.

[0060] In the above embodiment, the thickness of the active material layer 3 after pressing was measured by the in-line film thickness meter 68 of the roll press machine 60, but it may also be the thickness measured, for example, in an inspection process after the pressing process.

[0061] The above-described embodiments do not limit the present invention unless otherwise specified. Furthermore, the technology disclosed herein can be modified in various ways, and the components and processes described herein can be omitted or combined as appropriate, provided that no particular problems arise.

[0062] This specification includes the disclosures set forth in the following sections:

[0063] Section 1: A method for manufacturing an electrode sheet including a strip-shaped electrode foil and an active material layer formed on the electrode foil, a pressing step of continuously pressing the electrode sheet for each lot using a pair of opposing press rolls of a roll press machine; a setting step of setting initial press conditions of the roll press machine for each lot, in the pressing step, a thickness of the active material layer after pressing is measured, and pressing conditions of the roll press machine are feedback-controlled based on the measured thickness of the active material layer; The setting step includes: an estimation step of estimating the thickness of the active material layer of the immediately preceding lot from the initial press conditions of the immediately preceding lot and the feedback-controlled press conditions of the immediately preceding lot based on the initial press conditions and a predetermined correlation between the press conditions and the thickness of the active material layer; a correction value calculation step of calculating a difference between the thickness of the active material layer of the immediately preceding lot and the thickness of the active material layer of the immediately preceding lot estimated in the estimation step, and calculating a correction value for an initial pressing condition based on the correlation so as to correct the difference; a correcting step of adding the correction value to an initial press condition before correction to obtain the initial press condition. Manufacturing method of electrode sheet.

[0064] Section 2: a basis weight obtaining step of obtaining the basis weight of the active material layer for each lot of the electrode sheet, The correlation is a first correlation between the initial pressing conditions and the thickness of the active material layer, which is determined in advance for each basis weight of the active material layer; a second correlation determined in advance between the amount of change in the pressing conditions and the amount of change in the thickness of the active material layer; the setting step includes a pre-correction condition calculation step of determining the pre-correction initial press conditions in accordance with the basis weight acquired in the basis weight acquisition step, based on the first correlation; In the estimation step, a thickness of the active material layer of the immediately preceding lot is estimated based on the first correlation and the second correlation; In the correction value calculation step, the correction value is calculated based on the first correlation. Item 1. A method for producing an electrode sheet according to item 1.

[0065] Section 3: the feedback-controlled pressing conditions used in the estimation step are the pressing conditions at the end portion of the electrode sheet of the immediately previous lot, the thickness of the active material layer of the immediately preceding lot used in the correction value calculation step is the thickness of the active material layer at the end portion of the electrode sheet of the immediately preceding lot, measured in the pressing step; Item 1 or 2. A method for producing an electrode sheet according to item 1 or 2.

[0066] Section 4: the initial press condition includes a gap between the pair of press rolls; The press condition to be feedback-controlled is a press load. Item 4. A method for producing an electrode sheet according to any one of Items 1 to 3.

[0067] Section 5: The roll press machine is A pair of support members that support the pair of press rolls so that they can approach or separate from each other; a drive device that moves the pair of support members toward or away from each other; a gap setting member that is sandwiched between the pair of support members, the length of which is variable in the approaching / separating direction of the pair of support members, and that can set the gap between the pair of press rolls by adjusting the gap between the pair of support members, the setting step includes adjusting the length of the gap setting member to make the gap between the pair of press rolls coincide with the initial press condition; In the pressing step, the gap between the pair of press rolls is changed by elastic deformation of the gap setting member in response to a press load of the drive device that is feedback-controlled. Item 5. A method for producing an electrode sheet according to item 4.

[0068] Item 6: a roll press machine including a pair of opposing press rolls, which continuously presses an electrode sheet including a strip-shaped electrode foil and an active material layer formed on the electrode foil by the pair of press rolls for each lot; The roll press machine is a measuring device for measuring the thickness of the active material layer after pressing; a press control unit that feedback-controls press conditions based on the thickness of the active material layer measured by the measuring device; a setting unit that sets initial press conditions for each lot, The setting unit a storage unit that stores the initial pressing conditions and a predetermined correlation between the pressing conditions and the thickness of the active material layer; an estimation unit that estimates the thickness of the active material layer of the immediately preceding lot from the initial press conditions of the immediately preceding lot and the feedback-controlled press conditions of the immediately preceding lot based on the correlation; a correction value calculation unit that calculates a difference between the thickness of the active material layer of the immediately preceding lot measured by the measurement device and the thickness of the active material layer of the immediately preceding lot estimated by the estimation unit, and calculates a correction value for an initial pressing condition based on the correlation so as to correct the difference; a correction unit that calculates the initial press conditions by adding the correction value to the initial press conditions before correction. Electrode sheet manufacturing equipment.

[0069] Section 7: a basis weight acquisition device that acquires the basis weight of the active material for each lot of the electrode sheet, The correlation is a first correlation between the initial pressing conditions and the thickness of the active material layer, which is determined in advance for each basis weight of the active material layer; a second correlation determined in advance between the amount of change in the pressing conditions and the amount of change in the thickness of the active material layer; the setting unit includes a pre-correction condition calculation unit that determines the pre-correction initial press conditions in accordance with the basis weight acquired by the basis weight acquisition device based on the first correlation, the estimation unit estimates the thickness of the active material layer of the immediately preceding lot based on the first correlation and the second correlation; the correction value calculation unit calculates the correction value based on the first correlation. Item 7. The electrode sheet manufacturing apparatus according to item 6.

[0070] Section 8: the estimation unit estimates a thickness of the active material layer using feedback-controlled pressing conditions at the terminal end portion of the electrode sheet of the immediately previous lot; the correction value calculation unit calculates the correction value using a thickness of the active material layer measured at an end portion of the electrode sheet of the immediately preceding lot. Item 6. The electrode sheet manufacturing apparatus according to item 6 or 7.

[0071] Section 9: the initial press condition includes a gap between the pair of press rolls; The press condition to be feedback-controlled is a press load. Item 9. An electrode sheet manufacturing apparatus according to any one of Items 6 to 8.

[0072] Section 10: The roll press machine is A pair of support members that support the pair of press rolls so that they can approach or separate from each other; a drive device that moves the pair of support members toward or away from each other; a gap setting member that is sandwiched between the pair of support members, the length of which is variable in the approaching / separating direction of the pair of support members, and that can set the gap between the pair of press rolls by adjusting the gap between the pair of support members, the setting unit is configured to adjust the length of the gap setting member to make the gap between the pair of press rolls coincide with the initial press condition; The gap between the pair of press rolls is changed by elastic deformation of the gap setting member in response to the press load of the drive device feedback-controlled by the press control unit. Item 10. The electrode sheet manufacturing apparatus according to item 9. [Explanation of symbols]

[0073] 1 Electrode sheet 2 Electrode foil 3 Active material layer 10. Electrode sheet manufacturing equipment 20 Weighing device 30 Kneading equipment 40 Coating equipment 50 Drying equipment 60 Roll press machine 60A Unwinding Device 60B Press Device 60C winding device 61,62 Press roll 63, 64 Housing (support member) 65 Gap setting mechanism 65a Gap setting wedge (gap setting member) 66 Drive unit 66a Lifting wedge 67 Load Cell 68 In-line film thickness meter (measuring device) 69 Rotating Device 70 Control device 71 Press Control Section 72 Setting section 72A Storage section 72B Estimation part 72C Pre-correction condition calculation unit 72D Correction value calculation unit 72E Correction Unit 72F Idle operation control unit A Estimated thickness from initial press conditions B Measurement thickness D Estimated thickness change due to change in press pressure E Difference between estimated thickness and measured thickness F Initial press conditions before correction (press roll spacing) V correction value G1 Initial press conditions (press roll spacing) S10 Weighing process S20 Kneading process S30 coating process S40 Drying process S50 Basis weight acquisition process S60 setting process S60A Estimated process S60B Correction value calculation process S60C Pre-correction condition calculation process S60D correction process S70 Press Process

Claims

1. A method for manufacturing an electrode sheet including a strip-shaped electrode foil and an active material layer formed on the electrode foil, a pressing step of continuously pressing the electrode sheet for each lot using a pair of opposing press rolls of a roll press machine; a setting step of setting initial press conditions for the roll press machine for each lot; an idle operation step of rotating the pair of press rolls in a state where the electrode sheet is not supplied when the electrode sheet has not been pressed for a predetermined time or longer, in the pressing step, a thickness of the active material layer after pressing is measured, and pressing conditions of the roll press machine are feedback-controlled based on the measured thickness of the active material layer; The setting step includes: an estimation step of estimating the thickness of the active material layer of the immediately preceding lot from the initial press conditions of the immediately preceding lot and the feedback-controlled press conditions of the immediately preceding lot based on the initial press conditions and a predetermined correlation between the press conditions and the thickness of the active material layer; a correction value calculation step of calculating a difference between the thickness of the active material layer of the immediately preceding lot and the thickness of the active material layer of the immediately preceding lot estimated in the estimation step, and calculating a correction value for an initial pressing condition based on the correlation so as to correct the difference; a correcting step of adding the correction value to an initial press condition before correction to obtain the initial press condition. Manufacturing method of electrode sheet.

2. a basis weight obtaining step of obtaining the basis weight of the active material layer for each lot of the electrode sheet, The correlation is a first correlation between the initial pressing conditions and the thickness of the active material layer, which is determined in advance for each basis weight of the active material layer; a second correlation determined in advance between the amount of change in the pressing conditions and the amount of change in the thickness of the active material layer; the setting step includes a pre-correction condition calculation step of determining the pre-correction initial press conditions in accordance with the basis weight acquired in the basis weight acquisition step, based on the first correlation; In the estimation step, a thickness of the active material layer of the immediately preceding lot is estimated based on the first correlation and the second correlation; In the correction value calculation step, the correction value is calculated based on the first correlation. The method for producing the electrode sheet according to claim 1 .

3. the feedback-controlled pressing conditions used in the estimation step are the pressing conditions at the end portion of the electrode sheet of the immediately previous lot, the thickness of the active material layer of the immediately preceding lot used in the correction value calculation step is the thickness of the active material layer at the end portion of the electrode sheet of the immediately preceding lot, measured in the pressing step; The method for producing the electrode sheet according to claim 1 .

4. the initial press condition includes a gap between the pair of press rolls; The press condition to be feedback-controlled is a press load. The method for producing the electrode sheet according to claim 1 .

5. The roll press machine is A pair of support members that support the pair of press rolls so that they can approach or separate from each other; a drive device that moves the pair of support members toward or away from each other; a gap setting member that is sandwiched between the pair of support members, the length of which is variable in the approaching / separating direction of the pair of support members, and that can set the gap between the pair of press rolls by adjusting the gap between the pair of support members, the setting step includes adjusting the length of the gap setting member to make the gap between the pair of press rolls coincide with the initial press condition; In the pressing step, the gap between the pair of press rolls is changed by elastic deformation of the gap setting member in response to a press load of the drive device that is feedback-controlled. The method for producing the electrode sheet according to claim 4 .

6. a roll press machine including a pair of opposing press rolls, which continuously presses an electrode sheet including a strip-shaped electrode foil and an active material layer formed on the electrode foil by the pair of press rolls for each lot; The roll press machine is a measuring device for measuring the thickness of the active material layer after pressing; a press control unit that feedback-controls press conditions based on the thickness of the active material layer measured by the measuring device; a setting unit that sets initial press conditions for each lot; an idle operation control unit that rotates the pair of press rolls in a state where the electrode sheet is not supplied when the electrode sheet has not been pressed for a predetermined time or longer, The setting unit a storage unit that stores the initial pressing conditions and a predetermined correlation between the pressing conditions and the thickness of the active material layer; an estimation unit that estimates the thickness of the active material layer of the immediately preceding lot from the initial press conditions of the immediately preceding lot and the feedback-controlled press conditions of the immediately preceding lot based on the correlation; a correction value calculation unit that calculates a difference between the thickness of the active material layer of the immediately preceding lot measured by the measurement device and the thickness of the active material layer of the immediately preceding lot estimated by the estimation unit, and calculates a correction value for an initial pressing condition based on the correlation so as to correct the difference; a correction unit that calculates the initial press conditions by adding the correction value to the initial press conditions before correction. Electrode sheet manufacturing equipment.

7. a basis weight acquisition device that acquires the basis weight of the active material layer for each lot of the electrode sheet, The correlation is a first correlation between the initial pressing conditions and the thickness of the active material layer, which is determined in advance for each basis weight of the active material layer; a second correlation determined in advance between the amount of change in the pressing conditions and the amount of change in the thickness of the active material layer; the setting unit includes a pre-correction condition calculation unit that determines the pre-correction initial press conditions in accordance with the basis weight acquired by the basis weight acquisition device based on the first correlation, the estimation unit estimates the thickness of the active material layer of the immediately preceding lot based on the first correlation and the second correlation; the correction value calculation unit calculates the correction value based on the first correlation; The electrode sheet manufacturing apparatus according to claim 6 .

8. the estimation unit estimates a thickness of the active material layer using feedback-controlled pressing conditions at the terminal end portion of the electrode sheet of the immediately previous lot; the correction value calculation unit calculates the correction value using a thickness of the active material layer measured at an end portion of the electrode sheet of the immediately preceding lot. The electrode sheet manufacturing apparatus according to claim 6 .

9. the initial press condition includes a gap between the pair of press rolls; The press condition to be feedback-controlled is a press load. The electrode sheet manufacturing apparatus according to claim 6 .

10. The roll press machine is A pair of support members that support the pair of press rolls so that they can approach or separate from each other; a drive device that moves the pair of support members toward or away from each other; a gap setting member that is sandwiched between the pair of support members, the length of which is variable in the approaching / separating direction of the pair of support members, and that can set the gap between the pair of press rolls by adjusting the gap between the pair of support members, the setting unit is configured to adjust the length of the gap setting member to make the gap between the pair of press rolls coincide with the initial press condition; The gap between the pair of press rolls is changed by elastic deformation of the gap setting member in response to the press load of the drive device feedback-controlled by the press control unit. The electrode sheet manufacturing device according to claim 9 .

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