JP2016186945A - Lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery that can reduce the cost and enhance productivity by abolishing an insulation tape.SOLUTION: A lithium ion secondary battery 1 has a configuration that an electrode laminate M in which a positive electrode 2 and a negative electrode 3 are laminated while sandwiching a separator S therebetween and are encapsulated together with electrolytic solution in a laminate film 4. The positive electrode 2 includes a collector main body portion 5a, a narrow collector lead portion 5b, an active material layer 6, and a coating insulating material layer 7. The active material layer 6 contains an active material and binder, and the coating insulating material layer 7 contains the same binder as the binder contained in the active material layer 6. The active material 6 is formed so as to be overlapped with a part of the coating insulating material layer 7 from the upper side of the coating insulating layer 7 which is formed to straddle the boundary portion between the collector lead portion 5b and the collector main body portion 5a.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a lithium ion secondary battery representative of, for example, a laminate-type thin secondary battery.

  For example, as a thin lithium ion secondary battery using a laminate film outer package, a battery in which an electrode laminate in which a plurality of pairs of positive electrode sheets and negative electrode sheets are laminated together with a separator is stored inside the laminate film outer package is known. Each of the positive electrode sheet and the negative electrode sheet is a current collector made of aluminum or other metal foil, and the positive electrode sheet is left on the current collector while leaving a current collector exposed portion serving as a lead portion. For the negative electrode sheet, the negative electrode active material layer is formed on the current collector.

  In this case, although it is not a thin secondary battery using a laminate film outer package, for example, in Patent Document 1 and Patent Document 2, the current collector exposed part is in contact with the active material layer for the purpose of preventing a short circuit. A technique for applying an insulating tape is described.

JP 2006-19199 A Japanese Patent Laid-Open No. 11-86833

  However, the use of insulating tape not only increases the cost, but it also increases the speed of the production line in order to attach the insulating tape accurately to the boundary between the narrow current collector and the active material layer. However, there is still a limit, and there is still room for improvement in terms of productivity improvement.

  The present invention has been made paying attention to such a problem, and provides a structure of a lithium ion secondary battery in which the cost is reduced and the productivity is improved.

  The present invention is a structure of a lithium ion secondary battery in which an electrode laminate in which a large number of sets are laminated while sandwiching a separator between a positive electrode and a negative electrode and enclosed in an outer package together with an electrolytic solution, the positive electrode and the negative electrode At least one of the electrodes includes a current collector body, a current collector lead that is narrower than the current collector body, an active material layer applied to the current collector body, and a current collector. A coating insulating material layer formed at a boundary portion between the electric conductor lead portion and the active material layer.

  The active material layer includes an active material and a binder, and the coating insulating material layer includes the same binder as the binder included in the active material layer. The current collector lead portion and the current collector body The active material layer is formed so as to overlap a part of the coating insulating material layer from above the coating insulating material layer formed so as to straddle both at the boundary with the part. is there.

  According to the present invention, a coating insulating material layer is formed by applying and drying an insulating material slurry instead of an insulating tape, so that the cost can be reduced and the production line can be increased in speed. , Improve productivity.

It is a figure which shows schematic structure of a laminated film exterior body type thin lithium ion secondary battery, (A) is a top view, (B) is an expanded sectional view along the aa line | wire of the same figure (A). FIG. 2 is an exploded explanatory view of an electrode laminate in the battery shown in FIG. 1. It is a figure which shows the structure of the positive electrode sheet used for the electrode laminated body shown to FIG.1, 2, (A) is plane explanatory drawing, (B) The front explanatory drawing of the same figure (A). The typical explanatory view of the whole manufacturing process of a positive electrode sheet. The principal part expansion explanatory drawing of FIG. It is a figure which shows the detail of the coating head in the coating apparatus of FIG. 5, (A) is sectional explanatory drawing in alignment with the aa line of the figure (D), (B) is plane explanatory drawing of the figure (A). (C) is the bottom view of the same figure (A), (D) is right side explanatory drawing of the same figure (A). Plane explanatory drawing of each of the 1st-3rd die plate which is a component of the coating head of FIG. Explanatory drawing which shows the progress in the manufacturing process of FIG. Explanatory drawing which shows the progress in the manufacturing process following FIG. The principal part perspective view which shows the detail of the 1st cutting machine of FIG. It is a figure which shows the other manufacturing method of a positive electrode sheet, and is explanatory drawing which shows the progress in the manufacturing process of FIG. Explanatory drawing which shows the progress in the manufacturing process following FIG.

  FIGS. 1-9 show the more concrete form for implementing the lithium ion secondary battery which concerns on this invention, and here, as shown in FIG. The electrode stack M is a pair of current collector leads 5b and 50b that function as terminals (tabs) so as to protrude from the same side of the exterior body. The example in the case of manufacturing the electrode sheet used is shown.

  1A is a plan view of the secondary battery 1, and FIG. 1B is an enlarged cross-sectional view taken along the line aa of FIG. 1A. 2 shows an exploded explanatory view of the electrode laminate M in FIG. 1, and FIG. 3 shows details of the positive electrode sheet 2 alone in FIG.

  As shown in FIGS. 1 and 2, the secondary battery 1 is formed by laminating a large number of sets of separators S sandwiched between a positive electrode sheet 2 as a positive electrode and a negative electrode sheet 3 as a negative electrode, both of which are rectangular. With the electrode laminate M as a main element, the electrode laminate M is enclosed in a pair of laminate films 4 having a composite structure as an exterior body joined together.

  The positive electrode sheet 2 and the negative electrode sheet 3 are both so-called current collectors, each of which is based on a current collector made of aluminum, copper or other metal foil (current collector foil), as will be described later. For the positive electrode sheet 2, the positive electrode active material layer is formed on the current collector body 5a of the current collector 5 while leaving the current collector exposed portion (active material uncoated portion) to be the lead portion 5b or 50b. Similarly, the electrode sheet 3 has a negative electrode active material layer formed on the current collector body. And the electrode laminated body M formed by alternately laminating the positive electrode sheet 2 and the electrode electrode sheet 3 with the separator S interposed therebetween is a pair of current collector lead portions 5b, 50b each of which is an exterior body. The peripheral portions of the pair of laminate films 4 are overlapped with each other so as to protrude from the same side of the laminate film 4 to the outside as a terminal (tab), and then joined together by means such as heat fusion. In this way, the electrode laminate M is surrounded by the pair of bag-like laminate films 4 whose peripheral portions are joined to each other, and the electrolytic solution is enclosed inside.

  In the example of FIG. 1, a part of each of the current collector lead parts 5 b and 50 b protrudes as a terminal (tab) to the outside of the pair of laminate films 4 as an exterior body, but instead of this structure, A positive electrode terminal is electrically connected to the positive electrode current collector lead portion 5b, and a negative electrode terminal of the negative electrode current collector lead portion 50b is electrically connected to each other, and a pair of laminate films in which the positive electrode terminal and the negative electrode terminal are exterior bodies. It is good also as a structure which protrudes outside from the same 4 side.

  FIG. 3 shows a state of the positive electrode sheet 2 alone in the electrode laminate M in FIGS. 1 and 2. The positive electrode sheet 2 has a current collector 5 made of, for example, an aluminum foil as a base, and a current collector. Reference numeral 5 denotes a current collector body 5a and a current collector lead 5b extended from the current collector body 5a. A positive electrode active material layer 6 is formed on the current collector main body 5 a of the current collector 5, and the current collector is narrower than the current collector main body 5 a on which the positive electrode active material layer 6 is formed. The body exposed portion (active material uncoated portion) is attached as a current collector lead portion 5b extending from the current collector body portion 5a. A coating insulating material layer 7 for preventing a short circuit is formed at the boundary portion between the positive electrode active material layer 6 and the current collector lead portion 5b so as to straddle both. Since the coating insulating material layer 7 is formed by applying the insulating material slurry 7A to the current collector sheet 5A by the coating device 9 together with the active material slurry 6A and drying it, as will be described later. Although it is referred to as a coating insulating material layer 7 in the sense of specifying the construction method, it is hereinafter simply referred to as an insulating material layer 7.

The positive electrode active material layer 6 is made of, for example, a fluid active material slurry obtained by mixing lithium manganate (LiMn ₂ O ₄ ) dissolved in a solvent and PVDF (polyvinylidene fluoride) as a binder on the current collector main body 5a. It is formed by applying to a predetermined thickness and then drying and fixing. As the insulating material layer 7, for example, a mixture of alumina (Al ₂ O ₃ ) and the same PVDF as the binder of the active material slurry is used.

  Such a structure is basically the same for the negative electrode sheet 3 although the materials of the current collector 5 and the active material 6 are different. Here, the insulating material layer 7 may be formed on at least one of the positive electrode sheet 2 and the negative electrode sheet 3. FIG. 3 shows an example in which the positive electrode active material layer 6 and the insulating material layer 7 are formed only on one surface of the current collector main body 5a. However, the positive electrode active material is formed on both surfaces of the current collector main body 5a. The layer 6 may be formed together with the insulating material layer 7. Further, the thickness dimensions of the current collector 5, the positive electrode active material layer 6, and the insulating material layer 7 in FIG. 3 are exaggerated for easy understanding of the structure, and the actual product thickness dimensions are shown. It does not indicate.

  FIG. 4 schematically shows, for example, the outline of the whole manufacturing process of the positive electrode sheet 2. In the manufacturing process shown in the figure, a current collector roll (feeding roll) 8 as a sheet roll in which a current collector sheet 5A having a predetermined width and a long foil shape as a base of the current collector 5 is wound several times. And a coating head (die coater) 10 of the coating apparatus 9, a dryer 11, a take-up roll 12, a first cutter 13, a second cutter 14, a recovery area 16, and a finish cutter 17. And.

  The long foil-shaped current collector sheet 5A fed from the current collector roll 8 is guided so as to be wound around the guide rolls 17 and 19, the backup roll 18 and the take-up roll 12. Then, with the wound state, the current collector sheet 5A travels at a predetermined speed while being applied with a predetermined tension, and is taken up by the first cutter 13 side.

  The coating head 10 of the coating device 9 is disposed so as to be close to the portion where the current collector 5 </ b> A is wound by the backup roll 18. In the process in which the current collector sheet 5A travels while being backed up by the backup roll 18, an active material slurry and an insulating material slurry are discharged from a discharge port of the coating head 10 described later and applied to the current collector sheet 5A with a predetermined thickness. (Coating) The active material slurry and the insulating material slurry applied to the current collector sheet 5A are dried in the process of passing through the dryer 11, and fixed to the current collector sheet 5A as the respective coating films of the active material layer 6 and the insulating material layer 7. Then, it passes through the guide roll 19 and the take-up roll 12 and is taken to the first cutting machine 13 side.

  Here, as the positive electrode sheet 2, in addition to the type in which the positive electrode active material layer 6 and the insulating material layer 7 are formed on one surface of the current collector 5 as shown in FIG. 3, the positive electrode active material is formed on both surfaces of the current collector 5. As described above, there is a type in which the layer 6 and the insulating material layer 7 are formed. When manufacturing the positive electrode sheet having the positive electrode active material layer 6 and the insulating material layer 7 on both surfaces, the positive electrode active material layer 6 and the insulating material layer 7 were formed on one surface through the dryer 11. The current collector sheet 5A is once wound up by the take-up roll 12 to form a roll, and then the roll is supplied as the current collector roll 8 of FIG. 4, and the positive electrode active material layer 6 and the insulation are provided on the other surface. The material layer 7 is formed.

  And in the 1st cutting machine 13, the 2nd cutting machine 14, and the finishing cutting machine 16 of the back | latter stage of the take-up roll 12, it cut | disconnects the elongate collector sheet 5A with a some cutting line so that it may mention later. A plurality of strip-like positive electrode sheets 2 as shown in FIG.

  FIG. 5 shows the details of the coating apparatus 9 in FIG. 4. In this embodiment, the active material slurry and the insulating material that become the positive electrode active material layer 6 of FIG. 3 with a common and single coating head 10. A characteristic is that both of the insulating material slurry to be the layer 7 are applied to the current collector sheet 5A (5) simultaneously or substantially simultaneously.

  As shown in FIG. 5, the coating apparatus 9 includes slurry tanks 20 and 21 as slurry-like substance supply sources in which an active material slurry 6A and an insulating material slurry 7A are separately stored, in addition to the coating head 10. The active material slurry 6A is supplied from the one slurry tank 20 to the coating head 10 by the pump 22 and the insulating material slurry 7A is supplied from the other slurry tank 21 by the pump 23. become. Each slurry supply path 24, 25 is provided with an open / close valve 26 or 27. The timings of discharge and discharge stop of the active material slurry 6A and the insulating material slurry 7A from the coating head 10 are controlled by a controller (not shown).

  FIG. 6 shows details of the coating head 10. The coating head 10 superimposes the first to third die plates 28, 29, 30 shown in FIG. The die plates 28 to 30 are sandwiched between the holder plates 31 and 32 on the lower side, and then fastened with bolts or the like not shown.

  As shown in FIG. 6, the upper side holder plate 31 has a semicircular cross section and a rectangular chamber portion 41 as viewed from the first die plate 28, and an air vent hole 42 is formed therein. The vent hole 42 communicates with the active material slurry passage 33 in the coating head 10, and an open / close valve 43 is attached to the open side of the air vent hole 42.

  Further, the lower side holder plate 32 is insulated from the inlet 39 of the active material slurry together with the chamber portions 37 and 38 which are semicircular in cross section and rectangular as viewed from the third die plate 30 as shown in FIG. As shown in FIG. 5, the active material slurry inlet 39 is provided in the active material slurry supply path 24, and the insulating material slurry inlet 40 is provided in the insulating material slurry. Are respectively connected to the supply path 25.

  As shown in FIG. 7A, the uppermost first die plate 28 has a relatively large rectangular opening 28a formed at the center thereof, so that the first die plate 28 itself is formed. Is formed as a so-called hollow frame shape. The size of the opening 28 includes the chamber 41 of the holder plate 31 on the upper side. The second die plate 29 at the center is formed with a relatively small opening 29a that overlaps the opening 28a on the first die plate 28 side, as shown in FIG. Further, the lowermost third die plate 30 has a chamber portion of the lower side holder plate 32 having the same size as the opening 29a on the second die plate 29 side, as shown in FIG. 37 is provided with an opening 30a that overlaps 37, and two relatively small openings 30b that overlap with the chamber 38 of the lower holder plate 32 are formed. Further, a slot portion 30c having a width narrower than that of the opening portion 30b is formed to extend on one side portion of the two opening portions 30b. The same width may be used instead of the narrow width.

  Then, as described above, the first to third die plates 28 to 30 shown in FIG. 7 are overlapped with each other, and as shown in FIG. The die plates 28 to 30 are sandwiched between them and fastened with bolts or the like not shown in the figure, and as is apparent from the figure, the coating head 10 is insulated from the passage 33 of the active material slurry. And a pair of left and right insulating materials communicating with the insulating material slurry passage 34 below the second die plate 29 on the front end surface of the coating head 10. A slurry discharge port 35 is formed on the upper side of the second die plate 29, and an active material slurry discharge port 36 communicating with the active material slurry passage 33 is opened.

  Since the active material slurry needs to be stably discharged with higher accuracy than the insulating material slurry, it is necessary to secure a large capacity of the corresponding chamber portion. Therefore, when two types of slurry, that is, an active material slurry and an insulating material slurry are discharged almost simultaneously by a single coating head 10, one of the upper side holder plate 31 and the lower side holder plate 32 is used. If the active material slurry is caused to flow from the other side and the insulating material slurry is caused to flow from the other holder plate, the chamber portion may be only on one side, and the volume of the chamber portion may be insufficient.

  Therefore, in the coating head 10 shown in FIGS. 6 and 7, the opening 28a of the first die plate 28 is provided between the chamber portion 41 of the upper holder plate 31 and the chamber portion 37 of the lower holder plate 32. An opening 29a of the second die plate 29 and an opening 30a of the third die plate 30 are provided, and a sufficient capacity is secured by connecting them. In such a structure, air may be accumulated in the chamber portion 41 of the upper side holder plate 31, so the air vent hole 42 and the on-off valve 43 are provided.

  FIG. 8 shows the details of the coating process by the coating apparatus 9 shown in FIGS. As shown in the figure, a long current collector sheet 5A having a predetermined width and drawn from the current collector roll 8 of FIG. 4 is continuously backed up by a backup roll 18 at a predetermined speed in the arrow Q1 direction. Running. In addition, as shown in FIGS. 4 and 5, the coating head 10 disposed opposite to the backup roll 18 with the current collector sheet 5 </ b> A interposed therebetween is of a fixed position type. The active material slurry and the insulating material slurry are discharged simultaneously. However, as will be described later, while the active material slurry is continuously discharged, the insulating material slurry is intermittently discharged.

  The traveling direction of the current collector sheet 5A with respect to the coating head 10 shown in FIGS. 6A and 6D is upward, but in FIGS. 8 and 9, the current collector sheet 5A is shown for convenience of explanation. The direction of travel is downward.

  As shown in FIGS. 8A to 8F, in the process in which the long current collector sheet 5A, which is backed up by the backup roll 18, is continuously running, the coating head 10 removes FIG. When both the active material slurry 6A and the insulating material slurry 7A are discharged as described above, the active material slurry 6A is continuously applied with a predetermined width in the longitudinal direction of the current collector sheet 5A, and the application width of the active material slurry 6A. The insulating material slurry 7A is intermittently applied in the longitudinal direction of the current collector sheet 5A at predetermined intervals (pitch) at both ends of the current collector.

  In this case, the active material slurry 6A and the insulating material slurry 7A are made current collectors by causing the discharge timing of the insulating material slurry 7A to slightly precede the active material slurry 6A at the application position of the insulating material slurry 7A. The sheets overlap each other by a predetermined amount in the width direction of the sheet 5A. The application width of the active material slurry 6A including the insulating material slurry 7A is set to be smaller than the width dimension of the current collector sheet 5A.

  The current collector sheet 5A thus coated with both the active material slurry 6A and the insulating material slurry 7A passes through the dryer 11 shown in FIG. 4 so that the active material slurry 6A and the insulating material slurry 7A are dried. -By solidifying, it is fixed to the current collector sheet 5 </ b> A to become the active material layer 6 and the insulating material layer 7.

  In addition, although FIG. 8 shows an example of a single continuous coating on the current collector sheet 5A, the present invention is not limited to this, and two or more multiple coatings are also possible.

  FIG. 9 shows the details of the cutting process in the first cutting machine 13, the second cutting machine 14 and the finishing cutting machine 16 after passing through the dryer 11 of FIG.

  In addition to (a) and (b) of FIG. 9 and as shown in FIG. 10, the first cutter 13 is provided with a rotary cutter 47 in addition to guide rolls 44, 45, and 46, and collects current at a predetermined speed. By applying the rotary cutter 47 to the body sheet 5A, the current collector sheet 5A is cut along a cutting line along the longitudinal direction of the current collector sheet 5A, that is, a cutting line C1 that bisects the current collector sheet 5A in the width direction. Cut into two narrow current collector sheets 5B. Then, the bisected narrow current collector sheet 5B is taken to the second cutting machine 14 side in the subsequent stage. Note that the cutting line C1 is not necessary in the case of an embodiment that does not bisect, that is, in the case of only one line on the left side of FIG.

  On the other hand, a plurality of straight blade type cutters (not shown) are prepared in the second cutter 14 and, as shown in FIGS. 9B and 9C, along the longitudinal direction of the current collector sheet 5A. Each of the narrow current collector sheets 5B is cut and divided in the longitudinal direction at a plurality of (four) cutting lines C2 along the width direction of the current collector sheet 5A. Then, three strip-shaped electrode sheet pieces 5C are cut out individually from each narrow current collector sheet 5B. Thereby, the continuity in the longitudinal direction of the initial current collector sheet 5A is cut off, and a total of six strip-shaped sheets are collected from the current collector sheet 5A having the initial width W by passing through the second cutter 14. The electrode sheet piece 5C is cut out simultaneously. Then, a total of six strip-shaped electrode sheet pieces 5C obtained by the second cutting machine 14 are aligned and stacked, and are temporarily collected in the subsequent collection area 15.

  Here, as shown in FIG. 9D, each strip-shaped electrode sheet piece 5 </ b> C has incompletely collected current collector exposed portions or active material uncoated portions having the same width as the active material layer 6. It is attached as an electrical lead part (current collector extension part) 2A. Therefore, the plurality of strip-shaped electrode sheet pieces 5C collected in the collection area 15 in FIG. 4 are further sent to the finishing cutter 16 in the subsequent stage, as shown in FIGS. 9 (d) and 9 (e). Then, a part of the incomplete current collector lead 2A is cut and removed by two cutting lines C3 orthogonal to each other. By doing so, as shown in FIG. 3, the current collector body 5a having the positive electrode active material layer 6 formed on the surface thereof is connected to one side of the current collector body 5a and is narrower than the one side. The positive electrode sheet 2 having the current collector lead portion 5b is obtained for the first time.

  As is clear from the above description, the operation in the coating apparatus 9 in FIGS. 4 and 5 corresponds to a coating process for coating the active material slurry 6A and the insulating material slurry 7A, and drying in the dryer 11 is performed. The work corresponds to a drying process. Further, the cutting (cutting) work by the first cutting machine 13 and the second cutting machine 14 in FIG. 4 corresponds to a cutting process for forming a plurality of electrode sheet pieces 5C. Similarly, the finishing cutting machine 16 in FIG. The cutting (cutting) operation in step 1 corresponds to a finish cutting step of finishing the electrode sheet piece 5C into the electrode sheet 2.

  As described above, according to the present embodiment, instead of the insulating tape, the insulating material slurry 7A is applied and dried, so that the boundary between the positive electrode active material layer 6 and the current collector lead portion 5b in the positive electrode sheet 2 is obtained. Since the insulating material layer 7 is formed, the cost can be reduced and the production line speed can be increased as compared with the case of using the insulating tape, and the productivity is excellent. In particular, by applying the insulating material slurry 7A together with the active material slurry 6A and drying both of the slurries 6A and 7A substantially simultaneously, the drying process of the insulating material slurry 7A alone can be eliminated, thus simplifying the manufacturing process. As a result, manufacturing costs can be further reduced. In addition, since a part of the incomplete current collector lead portion 2A is cut substantially in accordance with the width dimension of the insulating material layer 7, the cutting of the insulating material layer 7 is suppressed, so that the waste of the insulating material slurry 7A is wasted. This also contributes to further cost reduction. Further, since the overlap between the insulating material layer 7 and the active material slurry 6A can be reduced, the reduction in the effective area of the active material slurry can be minimized.

  The electrode sheet manufacturing method of the present embodiment can be applied to the manufacture of an electrode sheet having the active material layer 6 together with the insulating material layer 7 on both sides of the current collector 5 as described above. Needless to say, the present invention can also be applied to the production of the negative electrode sheet 3 shown in FIGS.

  In the above embodiment, as shown in FIG. 9, the insulating material slurry 7A is intermittently applied along the longitudinal direction of the current collector sheet 5A, while the active material slurry 6A is formed on the current collector sheet 5A. Although continuous application is performed along the longitudinal direction, six active material slurries 6A including the insulating material slurry 7A of FIG. 9C are intermittently applied along the longitudinal direction of the current collector sheet 5A. It is also possible to apply it.

  11 and 12 show another example of the electrode sheet manufacturing method based on the manufacturing process substantially similar to that shown in FIG.

  In FIG. 11, reference sign Q1 indicates the traveling direction of the long current collector sheet 5A drawn from the current collector roll 8 in FIG. 4, and as shown in FIG. Insulating material slurry 7A is intermittently applied to three positions in the width direction of sheet 5A, and then active material slurry 6A is collected so as to overlap with a plurality of insulating material slurries 7A as shown in FIG. It is applied in the form of stripes over the entire width of the body sheet 5A. The application of the plurality of insulating material slurries 7A and the striped application of the active material slurry 6A are defined as one cycle, and the above cycle is performed on the current collector sheet 5A as shown in FIGS. Repeat intermittently in the longitudinal direction.

  Here, the coating of the active material slurry 6A and the insulating material slurry 7A as described above is performed by changing the coating head 10 as shown in FIG. 6 into one for the active material slurry 6A and one for the insulating material slurry 7A. Each of the two coating heads can be easily implemented by arranging them in series in the running direction of the current collector sheet 5A.

  When two insulating materials are arranged in the width direction as shown in FIG. 8, two slots 30c may be used as in the third die plate 30 shown in FIG. 7, but as shown in FIG. The arrangement of the three insulating materials in the width direction can be realized by providing three slots 30c in the third die plate 30 in FIG.

  Subsequently, as shown in FIGS. 12A and 12B, the cutting line along the longitudinal direction of the current collector sheet 5 </ b> A, that is, the current collector sheet 5 </ b> A is obtained by the first cutter 13 of FIG. 4. The current collector sheet 5A is cut into three narrow current collector sheets 5D having a narrow width at two cutting lines C4 that are divided into three equal parts in the width direction.

  Further, as shown in FIG. 12 (c), in the second cutting machine 14 in FIG. 4, a cutting line orthogonal to the cutting line C4 along the longitudinal direction of the current collector sheet 5A, that is, the current collector Three narrow electrode sheet pieces 5D are cut and divided in the longitudinal direction at a plurality of cutting lines C5 along the width direction of the sheet 5A, respectively, and three strip-shaped strips are formed from each narrow current collector sheet 5D. The electrode sheet piece 5E is cut out individually. Thereby, the continuity in the longitudinal direction of the initial current collector sheet 5A is cut off, and a total of six strip-shaped sheets are collected from the current collector sheet 5A having the initial width W by passing through the second cutter 14. The electrode sheet piece 5E is cut out simultaneously. Then, a total of six strip-shaped electrode sheet pieces 5E obtained by the second cutting machine 14 are aligned and stacked, and are temporarily collected in the collection area 15 at the subsequent stage.

  Subsequently, the plurality of strip-shaped electrode sheet pieces 5E collected in the collection area 15 of FIG. 4 are further sent to the finishing cutter 16 at the subsequent stage, as shown in FIGS. 12 (c) and 12 (d). Then, a part of the incomplete current collector lead part (current collector extension part) 2A is cut and removed by two cutting lines C6 orthogonal to each other. By doing so, the positive electrode sheet 2 as shown in FIG. 3 is obtained.

  It goes without saying that the same effects as those of the first embodiment can be obtained also in such an electrode sheet manufacturing method.

DESCRIPTION OF SYMBOLS 1 ... Lithium ion secondary battery 2 ... Positive electrode sheet 3 ... Negative electrode sheet 4 ... Laminate film (exterior body)
DESCRIPTION OF SYMBOLS 5 ... Current collector 5a ... Current collector main body part 5b ... Current collector lead part 6 ... Positive electrode active material layer 7 ... Coating insulating material layer 50b ... Current collector lead part M ... Electrode laminated body S ... Separator

Claims (2)

A structure of a lithium ion secondary battery in which an electrode laminate in which a large number of sets are laminated while sandwiching a separator between a positive electrode and a negative electrode and enclosed in an outer package together with an electrolyte,
At least one of the positive electrode and the negative electrode includes a current collector main body, a current collector lead narrower than the current collector main body, and an active material applied to the current collector main body. And a coating insulating material layer formed at a boundary portion between the current collector lead portion and the active material layer,
The active material layer includes an active material and a binder, and the coating insulating material layer includes the same binder as the binder included in the active material layer.
The active material layer overlaps a part of the coating insulating material layer from above the coating insulating material layer formed so as to straddle the boundary portion between the current collector lead portion and the current collector main body portion. A lithium ion secondary battery characterized by being formed.   2. The lithium ion secondary battery according to claim 1, wherein the electrode including the current collector main body, the current collector lead, the active material layer, and the coating insulating material layer is a positive electrode.