JP6674297B2 - Electrode thickness measuring device - Google Patents

Description

  The present invention relates to an electrode body thickness measuring device for measuring the thickness of an active material layer intermittently applied on a current collector foil after rolling.

  Patent Document 1 discloses a rolling device for rolling an electrode body for a battery, and the electrode body is formed by continuously applying an active material layer on a current collector foil. This rolling device is a pre-rolling movement amount detector that detects a moving amount per unit time of the electrode body before rolling, and a post-rolling moving amount detector that detects a moving amount per unit time of the electrode body after rolling. And a thickness gauge for measuring the thickness of the electrode body after rolling. In the rolling device, the elongation amount of the electrode body obtained from each movement amount detected by the movement amount detector before rolling and the movement amount detector after rolling, and the thickness of the electrode body after rolling measured by a thickness gauge, Thus, the density of the active material layer of the electrode body is controlled.

JP 2000-188103 A

  When rolling an electrode body in which an active material layer is applied intermittently on a current collector foil using the rolling device of Patent Document 1, the active material layer extends in the length direction and the width direction. On the other hand, since the current collector foil in the portion where the active material layer is not applied does not extend in the width direction, wrinkles may be generated in the active material layer.

  Here, in the rolling device, the density of the active material layer is obtained based on the thickness of the active material layer after rolling.

  However, if the thickness of the active material layer having wrinkles is measured with a thickness gauge and the thickness is used for calculating the density of the active material layer, it is impossible to calculate an accurate density.

  In the present invention, the electrode body thickness measuring device for measuring the thickness of the active material layer applied intermittently on the current collector foil after rolling is provided on the downstream side of the rolling roller so as to transport the rolled electrode body. A guide roller, an annular protrusion protruding from the outer peripheral surface of the guide roller toward the outer periphery, and a thickness measuring device facing the annular protrusion.

  Thus, when the electrode body passes through the annular protrusion on the guide roller after rolling, wrinkles of the active material layer below the thickness measuring device are locally extended by the annular protrusion.

  ADVANTAGE OF THE INVENTION According to this invention, the accurate thickness of an active material layer can be measured with a thickness measuring device in the state where there is no wrinkle in the measurement part of the thickness of an active material layer.

It is an explanatory view of a rolling device of one example of the present invention. It is a top view of the rolling device of FIG. It is explanatory drawing which shows the state of the active material layer and the current collector foil before and after rolling. It is explanatory drawing which shows arrangement | positioning of the annular protrusion on a guide roller after rolling. It is explanatory drawing of the guide roller after rolling and the thickness measuring device after rolling seen from the rolling roller side. It is explanatory drawing of the annular protrusion of 2nd Example. It is explanatory drawing of the annular protrusion of 3rd Example. It is explanatory drawing of the annular protrusion of 4th Example. FIG. 9 is a cross-sectional view of the annular protrusion and the guide roller after rolling along the line AA in FIG. 8. It is explanatory drawing of the annular protrusion of 5th Example.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a rolling device 1 having the thickness measuring device of the present invention. The rolling device 1 is used for rolling an electrode body 2 of a battery, for example, a lithium ion secondary battery. The electrode body 2 is obtained by intermittently applying a slurry obtained by mixing an active material, a conductive auxiliary agent, a binder, an organic solvent, and the like to a current collector foil 3 (FIG. 2), for example, an aluminum foil or a copper foil, with a predetermined thickness on both surfaces. It is formed in a belt shape by coating and drying. After the slurry is dried, a plurality of active material layers 4 indicated by dots in FIG. 2 are formed on both surfaces of the current collector foil 3 at predetermined intervals.

  The rolling device 1 includes a delivery roll 5 that delivers the dried strip-shaped electrode body 2 wound in a roll shape, and first and second pre-rolling members that guide the electrode body 2 delivered from the delivery roll 5. Guide rollers 6 and 7, a pair of upper and lower rolling rollers 8 and 8 for rolling the electrode body 2, and a cylindrical or cylindrical post-rolling guide roller 9 for guiding the electrode body 2 passing through the rolling rollers 8 and 8. A pair of upper and lower image processing units 10 and 10 for checking the quality of the electrode body 2 after rolling, a marking unit 11 for marking a defective product of the electrode body 2 discovered by the image processing units 10 and 10, And a take-up roll 13 for winding the electrode body 2 delivered from the delivery roll 5. The winding roll 13 is biaxial so that the winding of the electrode body 2 before cutting and the winding of the electrode body 2 after cutting the electrode body 2 of a predetermined length can be alternately performed. It is configured.

  In the above-mentioned rolling device 1, when the delivery roll 5 rotates clockwise in the drawing, the strip-shaped electrode body 2 is divided into the first and second pre-rolling guide rollers 6, 7, the rolling rollers 8, 8, and the post-rolling guide. It is continuously supplied to the roller 9, the image processing units 10 and 10, the marking unit 11, the cutting unit 12, and the take-up roll 13.

  Above and to the left of the second pre-rolling guide roller 7, a plurality of rolls for measuring the thickness of the active material layer 4 before rolling, specifically, the thickness of the entire electrode body 2 including the active material layers 4 on both surfaces. A front thickness measuring device 14 is provided to face the second pre-rolling guide roller 7. On the other hand, above the guide roller 9 after rolling, a plurality of thickness measurements after rolling for measuring the thickness of the active material layer 4 after rolling, specifically, the entire thickness of the electrode body 2 including the active material layers 4 on both surfaces. A device 15 is provided to face the guide roller 9 after rolling. The post-rolling thickness measuring device 15 is a non-contact type thickness measuring device, for example, a spectral interference laser displacement meter. In addition, by using the pre-rolling thickness measuring device 14 and the post-rolling thickness measuring device 15 to determine the relatively thin thickness due to the inclination or fading of the active material layer 4 at the start and end of the coating of the active material layer 4, the rolling is performed. The coating lengths of the front and rear active material layers 4 are respectively measured.

  Here, for convenience of the following description, the X direction in FIG. 2 which is the length direction of the active material layer 4 is defined as “the length direction of the active material layer”, and is the width direction of the active material layer 4. The Y direction of No. 2 is defined as "active material layer width direction".

  In the present embodiment, as shown in FIG. 2, three pre-roll thickness gauges 14, 14, 14 and three post-roll thickness gauges 15, 15, 15 are provided along the active material layer width direction Y in a predetermined direction. Each is provided at intervals.

  Further, a pair of upper and lower pre-roll width measuring devices 16 and 16 for measuring the width of the active material layer 4 before rolling are provided between the pre-rolling thickness measuring device 14 and the pair of rolling rolls 8 and 8. It is provided on each side of the electrode body 2 along the direction Y. On the other hand, on the downstream side of the post-rolling thickness measuring device 15, a pair of upper and lower post-rolling width measuring devices 17 and 17 for measuring the width of the active material layer 4 after rolling are similar to the pre-rolling width measuring devices 16 and 16, It is provided on both sides of the electrode body 2 along the width direction Y of the active material layer.

  The rolling device 1 manages the quality of the electrode body 2 by calculating the density of the active material layer 4 after rolling. The density of the active material layer 4 is obtained by dividing the weight per unit area of the active material layers 4 on both surfaces of the current collector foil 3 (hereinafter, referred to as “deposition”) by the thickness of the active material layers 4 on both surfaces after rolling. It is calculated by: After the rolling of the electrode body 2, in addition to the thickness of the active material layer 4 decreasing, as shown in an exaggerated manner in FIG. 3, the active material layer 4 has an active material layer length direction X and an active material layer width direction. Extends to both Y. Therefore, when calculating the density of the active material layer 4 after rolling, first, based on the coating length of the active material layer 4 before and after rolling measured by the thickness measuring devices 14 and 15, the active material layer 4 of the active material layer 4 is used. The amount of elongation in the length direction X is determined, and the amount of elongation in the active material layer width direction Y of the active material layer 4 is determined from the width of the active material layer 4 before and after rolling measured by the width measuring devices 16 and 17. Then, the deposition is calculated in consideration of these elongation amounts, and the deposition is divided by the thickness of the active material layer 4 measured by the thickness measuring device 15 after rolling.

  After the rolling of the electrode body 2, the active material layer 4 extends in both the active material layer length direction X and the active material layer width direction Y, but the current collector foil in a portion where the active material layer 4 is not applied. Since 3 does not extend in the width direction, wrinkles 18 having a corrugation may occur in the active material layer 4 after rolling. Furthermore, the location where the wrinkles 18 occur changes depending on the coating shape of the active material layer 4, the inclination of the electrode body 2 on the pass line, and the like. When the thickness of the active material layer 4 having the wrinkles 18 is measured, the thickness of the active material layer 4 which has become uneven due to the wrinkles 18 is measured, which is a factor for calculating an incorrect density of the active material layer 4. .

  Therefore, in the present embodiment, the thickness of the active material layer 4 after rolling is measured in a state where the influence of the wrinkles 18 generated in the active material layer 4 after rolling is eliminated.

  In this embodiment, as shown in FIG. 4, three annular projections 19, 19, 19 for locally extending the wrinkles 18 of the active material layer 4 after rolling are provided with three post-rolling thickness measuring devices 15, 15, 15. 15 (FIG. 2), it is attached to the guide roller 9 after rolling. Here, the inner diameter of the annular protrusion 19 corresponds to the outer diameter of the guide roller 9 after rolling, and the protrusion 19 is attached to the outer peripheral surface (contact surface) 9a of the guide roller 9 after rolling. Further, the protrusion 19 may be fitted into an annular recess formed in the guide roller 9 after rolling. In addition, the protrusion 19 may be formed integrally with the guide roller 9 after rolling.

  The annular projection 19 of this embodiment is made of a material having the same rigidity as the guide roller 9 after rolling. The post-rolling guide roller 9 is made of, for example, steel or stainless steel (SUS). Therefore, the annular projection 19 is made of steel or stainless steel, similarly to the guide roller 9 after rolling.

  The annular projection 19 protrudes from the outer peripheral surface 9a of the guide roller 9 after rolling to the outer peripheral side. The protrusion height of the protrusion 19 is set to such a height that transfer streaks do not occur in the active material layer 4 when the electrode body 2 is conveyed while being pressed locally against the protrusion 19. In one example, the protrusion height of the projection 19 is about several millimeters. The width W of the protrusion 19 is set to be smaller than the interval between the wrinkles 18 of the active material layer 4 after rolling. In one example, the width W of the protrusion 19 is about 6 mm. This prevents the protrusions 19 from coming into contact with the wrinkles 18 adjacent to the wrinkles 18 to be stretched, thereby preventing the active material layer 4 from sagging or generating new wrinkles 18.

  As shown in FIG. 5, the annular projection 19 has a contact surface 20 that comes into contact with the lower surface 2 a of the electrode body 2, and this contact surface 20 is located at the center where the thickness of the active material layer 4 is measured. It has a flat surface 20a, and arcuate surfaces 20b, 20b that are convex outward on both sides of the flat surface 20a. The flat surface 20a is opposed to the measurement surface 15a of the thickness gauge 15 after rolling.

  When the rolled electrode body 2 passes through the protrusions 19 and the rolled guide rollers 9, tension is applied to the electrode body 2 with the winding of the winding roll 13, so that the electrode body 2 is a post-roll thickness measuring instrument. It is locally pressed against the contact surface 20 of the projection 19 below the 15 measurement surfaces 15a. As a result, the wrinkles 18 of the active material layer 4 are locally extended in the width direction Y of the active material layer 4 while following the flat surface 20a and the circular arc surfaces 20b, 20b at the measurement position of the thickness of the active material layer 4 after rolling. It is.

  In FIG. 5, some wrinkles 18 actually occur on the active material layer 4 of the electrode body 2 which is in contact with the contact surface 9a of the guide roller 9 after rolling. Has been omitted.

  As described above, in the present embodiment, the wrinkles 18 of the active material layer 4 after rolling are locally stretched by the annular projections 19, so that there are no wrinkles 18 at the measurement positions of the thickness of the active material layer 4. In this state, the flat active material layer 4 is irradiated with a laser beam 21 (indicated by a dotted arrow in FIG. 5) from the post-rolling thickness measuring device 15 so that the accurate thickness of the rolled active material layer 4 (both sides) is obtained. Of the active material layer 4). Therefore, by dividing the deposition by the accurate thickness of the active material layer 4, the density of the active material layer 4 after rolling can be accurately calculated. Thereby, the quality control of the electrode body 2 after rolling is improved.

  Further, in this embodiment, since the annular projection 19 has the arcuate surfaces 20b, 20b on both sides of the flat surface 20a, the peeling of the active material layer 4 and the transfer streaks during the transport of the electrode body 2 after rolling. Can be prevented from occurring. If a portion corresponding to the arc surface 20b is formed by a corner, stress is concentrated on the corner by the tension applied to the electrode body 2 when the electrode body 2 is wound. 4 and transfer streaks easily occur. Therefore, by providing the arc surface 20b having a smooth curve, the stress on the contact surface 20 is reduced, and the peeling and the transfer streak of the active material layer 4 are prevented.

  FIG. 6 shows an annular projection 19 of the second embodiment. In the present embodiment, the annular projection 19 is made of a material different from that of the annular projection 19 shown in FIGS. It is desirable that the annular projection 19 has at least the rigidity of the side portion 27 that applies stress to the electrode body 2, that is, the arc surface 20b, lower than the rigidity of the contact surface 9a of the rolled guide roller 9 made of steel or stainless steel. More preferably, the rigidity of the arc surface 20 b (side portion 27) is preferably the same as the rigidity of the active material layer 4.

  In the present embodiment, the entire annular projection 19 is made of a material having the same rigidity as that of the active material layer 4 (indicated by dots in FIG. 6). The protrusion 19 is made of an elastic body, for example, rubber or fluororesin.

  In the second embodiment, since the annular protrusion 19 is made of a material having the same rigidity as the rigidity of the active material layer 4, for example, an elastic body, the elastic deformation of the annular protrusion 19 causes rolling. It is possible to absorb the stress applied to the contact surface 20, in particular, the circular arc surfaces 20b, 20b when the electrode body 2 is transported later. Thereby, peeling and transfer streaks of the active material layer 4 are more reliably prevented.

  FIG. 7 shows an annular projection 19 according to the third embodiment. In this embodiment, the projection 19 is composed of three parts, an annular projection base 22 having a flat surface 20a similar to that shown in FIGS. 4 to 6, and circular arc surfaces 20b and 20b similar to those shown in FIGS. And two annular projection side portions 23, 23 each having

  The projection base 22 is made of a material having the same rigidity as the guide roller 9 after rolling. The protrusion side portions 23 are made of a material having the same rigidity as that of the active material layer 4. For example, similarly to the above-described embodiment, the cover is made of rubber or fluorine resin.

  Therefore, according to the third embodiment as well, it is possible to absorb the stress applied to the arcuate surfaces 20b, 20b when the rolled electrode body 2 is transported.

  FIG. 8 shows an annular projection 19 of the fourth embodiment. In this embodiment, the annular projection 19 is composed of four parts, an annular projection base 24 (shown by hatching in FIG. 9) having a smaller outer diameter than the annular projection base 22 of the third embodiment, Protrusion side portions 23, 23 similar to the annular protrusion side portions 23, 23 of the third embodiment. Accordingly, an annular groove (not shown) having the outer peripheral surface 24a of the protrusion base 24 as a bottom surface is formed between the protrusion base 24 and the protrusion side portions 23, 23. An annular cover 25 having a width corresponding to the groove width is fitted into the annular groove. In the state in which the annular cover portion 25 is fitted, as shown in FIG. 9, the annular projection base 24 is attached to the outer peripheral surface 9 a of the guide roller 9 after rolling, and the annular projection base 24 is further annularly attached to the outer peripheral surface 24 a of the annular projection base 24. A cover 25 is attached. The projection base 24 may be formed integrally with the guide roller 9 after rolling.

  The protrusion side portions 23, 23 are made of a material having the same rigidity as that of the active material layer 4, for example, rubber or fluororesin, as in the third embodiment.

  The protrusion base 24 is made of a material having the same rigidity as the guide roller 9 after rolling, for example, steel or stainless steel. The annular cover portion 25 is made of a material having the same rigidity as that of the active material layer 4, for example, rubber or fluororesin, similarly to the protrusion side portion 23. Therefore, the central portion 28 of the annular protrusion 19, which is the measurement position of the thickness of the active material layer 4, is formed by the protrusion base 24 having relatively high rigidity on the inner peripheral side and the cover portion having relatively low rigidity on the outer peripheral side. 25.

  In the fourth embodiment, since the annular cover portion 25 is made of the same material as the annular projection side portions 23, 23, the entire contact surface 20 of the annular projection 19 is the same as in the second embodiment. In addition, it has the same rigidity as that of the active material layer 4. Therefore, similarly to the second embodiment, the annular projection 19 of the fourth embodiment can absorb the stress applied to the contact surface 20, particularly the arcuate surfaces 20b, 20b when the rolled electrode body 2 is transported. it can.

  FIG. 10 shows an annular projection 19 of the fifth embodiment. In the present embodiment, the annular projection base 22 of the embodiment of FIG. 7 is replaced with an annular heating section 26 having the same shape as the projection base 22. The annular heating unit 26 heats the electrode body 2 by, for example, emitting heat by an internal heater (not shown). Here, the heating temperature of the heating unit 26 is set to be lower by about 20 to 40 ° C. than the melting point of the binder in the active material layer 4. The heating width by the heating unit 26 (the width along the active material layer width direction Y in FIG. 10) is set to be smaller than the interval between the wrinkles 18.

  In the fifth embodiment, since the electrode unit 2 after rolling is heated by the heating unit 26, the binder in the active material layer 4 is softened, so that the active material layer 4 It is easy to move along the contact surface 20, especially the flat surface 26a of the heating unit 26. Therefore, the wrinkles 18 of the active material layer 4 after rolling are easily extended along the contact surface 20 of the projection 19.

DESCRIPTION OF SYMBOLS 1 ... Rolling device 2 ... Electrode body 3 ... Current collecting foil 4 ... Active material layer 8 ... Rolling roller 9 ... Guide roller 15 after rolling ... Thickness measuring device 19 after rolling ··· Projection 20 ··· Contact surface 20a ··· Flat surface 20b ··· Arc surface 22 ··· Projection base 23 ··· Projection side 24 ··· Projection base 25 ··· Cover Unit 26: heating unit

Claims (6)

An electrode body thickness measuring device that measures the thickness of the active material layer applied intermittently on the current collector foil after rolling,
A guide roller provided downstream of the rolling roller so as to transport the electrode body after rolling,
An annular protrusion protruding from the outer peripheral surface of the guide roller to the outer peripheral side,
A thickness measuring device facing the annular protrusion,
Thickness measuring device equipped with.   The thickness measuring device according to claim 1, wherein rigidity of at least a side portion of the annular protrusion is lower than rigidity of a contact surface of the guide roller.   The annular projection has a central annular projection base serving as a thickness measurement position, and annular projection sides on both sides of the annular projection base, and the annular projection side includes the annular projection. The thickness measuring device according to claim 1, wherein the rigidity is lower than that of the base.   A central portion serving as a thickness measurement position of the annular protrusion has an inner peripheral side relatively high rigidity annular base and a relatively low rigidity annular cover attached to an outer peripheral surface of the annular protrusion base. The thickness measuring device according to any one of claims 1 to 3, comprising a part. The annular protrusion has a flat surface having a flat portion in a direction substantially horizontal to a width direction of the electrode body conveyed by the rolling roller , and outer edges of the flat portion of the flat surface on both sides of the flat surface. The thickness measuring device according to any one of claims 1 to 4, further comprising: an arc surface extending from an outer surface of the guide roller toward an outer peripheral surface of the guide roller, the arc surface being convex outward .   The thickness measuring device according to claim 1, wherein the annular protrusion includes a heating unit.

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