JP6275956B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery having a flat wound electrode body and having high long-term reliability.

  As a power source for driving electric vehicles (EV) and hybrid electric vehicles (HEV, PHEV), high capacity and high output characteristics are required. Therefore, each battery is increased in size and a large number of batteries are connected in series and in parallel. Or it is used in series-parallel connection. As these batteries, square secondary batteries are widely used from the viewpoint of space efficiency.

  A prismatic secondary battery, for example, a prismatic non-aqueous electrolyte secondary battery is manufactured as follows. A positive electrode plate is produced in which a positive electrode active material mixture layer containing a positive electrode active material is formed on both surfaces of a positive electrode core made of an elongated sheet-like aluminum foil or the like. A negative electrode plate is prepared in which a negative electrode active material mixture layer containing a negative electrode active material is formed on both surfaces of a negative electrode core made of an elongated sheet-like copper foil or the like.

  Then, the negative electrode plate and the positive electrode plate are arranged with a separator interposed therebetween, and the negative electrode plate and the positive electrode plate are spirally wound around a cylindrical core while being insulated from each other by the separator. In this way, a cylindrical wound electrode body is produced, and the winding end portion of the separator is fixed with a winding tape. The cylindrical wound electrode body is crushed by a press machine and formed into a flat wound electrode body. Thereafter, the flat wound electrode body is accommodated in the rectangular exterior body, the opening portion of the battery exterior body is sealed except for the electrolyte solution injection hole, the electrolyte solution is injected, and then the electrolyte solution injection hole is closed. Therefore, a square nonaqueous electrolyte secondary battery is obtained (see Patent Document 1 below).

  In a nonaqueous electrolyte secondary battery, it is necessary to make the charge capacity ratio of the negative electrode plate and the positive electrode plate (negative electrode charge capacity / positive electrode charge capacity) greater than 1 in order to suppress lithium metal deposition during charging. is there. Therefore, in the prismatic nonaqueous electrolyte secondary battery disclosed in Patent Document 1 below, the end of the negative electrode active material mixture layer on the negative electrode core exposed portion side in the flat wound electrode body is the positive electrode in the adjacent positive electrode plate. The electrode plate protruding from the end portion of the active material mixture layer and located on the outer peripheral side is a negative electrode plate.

JP 2011-171250 A

  In the rectangular nonaqueous electrolyte secondary battery disclosed in Patent Document 1, the portion where the negative electrode plate located on the outermost peripheral side of the flat portion of the flat wound electrode body is opposed to the positive electrode plate is more peripheral. It is fixed only by the separator existing on the side. However, along with the looseness of the separator that occurs in the battery manufacturing process, the portion of the flat part of the flat wound electrode body where the negative electrode plate located on the outermost peripheral side faces the positive electrode plate is loosened in the winding direction. When this occurs, the electrode plate distance between the positive electrode plate existing on the inner peripheral side cannot be kept constant. If the electrode plate distance between the positive electrode plate and the negative electrode plate cannot be kept constant, uneven charging / discharging occurs, causing partial deterioration of the battery, resulting in low battery long-term reliability.

The secondary battery of one embodiment of the present invention includes:
A flat winding in which a positive electrode plate having a positive electrode active material mixture layer formed on a positive electrode core and a negative electrode plate having a negative electrode active material mixture layer formed on a negative electrode core are wound through a separator. An electrode body,
A wound positive electrode core exposed portion is formed at one end of the flat wound electrode body,
A wound negative electrode core exposed portion is formed at the other end of the flat wound electrode body,
The wound positive electrode core exposed portion is converged and a positive electrode current collector is connected,
The wound negative electrode core exposed part is converged and a negative electrode current collector is connected,
The end of winding of the negative electrode plate is located on the outer peripheral side of the flat wound electrode body than the end of winding of the positive electrode plate,
The outermost peripheral area of the negative electrode plate is provided with a lifting prevention means for preventing the separator from being lifted from the inner peripheral side of the outermost peripheral area of the negative electrode plate.

  According to the secondary battery of one aspect of the present invention, since the outermost negative electrode plate is fixed by the lifting prevention means, the outermost negative electrode plate is prevented from being lifted or displaced due to loosening of the separator that occurs in the battery manufacturing process. Thus, partial deterioration due to uneven charging / discharging of the battery can be suppressed. In addition, as a floating prevention means, a tape, a heat-shrinkable film, etc. can be used.

FIG. 3 is a partial development view showing a positional relationship between an electrode plate and a separator when a wound electrode body of a rectangular nonaqueous electrolyte secondary battery is manufactured. 2A is a cross-sectional view of a prismatic nonaqueous electrolyte secondary battery, FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG. 2A, and FIG. 2C is a cross-sectional view taken along line IIC-IIC in FIG. is there. FIG. 3 is a perspective view after the flat wound electrode body according to the first embodiment is molded. It is a perspective view after shaping | molding of the flat winding electrode body which concerns on a comparative example. It is a model cross-sectional view of the flat winding electrode body of a comparative example. It is a perspective view after shaping | molding of the flat winding electrode body which concerns on Embodiment 2. FIG. It is a perspective view after shaping | molding of the flat winding electrode body which concerns on Embodiment 3. FIG. It is a perspective view after shaping | molding of the flat winding electrode body which concerns on Embodiment 4. FIG. FIG. 10 is a perspective view after the flat wound electrode body according to the fifth embodiment is molded. 10A is a schematic enlarged view of a positive electrode current collector portion of a flat wound electrode body according to Embodiment 6, and FIG. 10B is an enlarged cross-sectional view taken along line XB-XB in FIG. 10A. It is a perspective view after shaping | molding of the flat winding electrode body which concerns on Embodiment 7. FIG.

  A prismatic nonaqueous electrolyte secondary battery as a prismatic secondary battery common to the embodiments and comparative examples of the present invention will be described in detail with reference to FIGS. 1 and 2. However, the prismatic nonaqueous electrolyte secondary battery shown below is exemplified for understanding the technical idea of the present invention, and the present invention is intended to specify the prismatic nonaqueous electrolyte secondary battery. is not. The present invention can be equally applied to various changes made without departing from the technical idea shown in the claims.

  This rectangular non-aqueous electrolyte secondary battery 10 has a flat wound electrode body 14 in which a positive electrode plate 11 and a negative electrode plate 12 are wound via a separator 13. The positive electrode plate 11 is produced by applying a positive electrode active material mixture slurry on both surfaces of a positive electrode core made of aluminum foil, drying and rolling, and then slitting the aluminum foil so as to be exposed in a strip shape. Moreover, the negative electrode plate 12 is produced by applying a negative electrode active material mixture slurry on both surfaces of a negative electrode core made of copper foil, drying and rolling, and then slitting so that the copper foil is exposed in a strip shape. .

  Then, the positive electrode plate 11 and the negative electrode plate 12 obtained as described above are used to expose the aluminum foil (hereinafter referred to as “positive electrode core”) exposed portion 15 of the positive electrode plate 11 and the copper foil (hereinafter referred to as “negative electrode”). The exposed portion 16 (which is referred to as a “core body” is shifted so as not to overlap the positive electrode active material mixture layer 11a and the negative electrode active material mixture layer 12a of the electrodes facing each other, and wound around the polyolefin porous separator 13 Thus, the negative electrode core is provided with the positive electrode core exposed portion 15 that is wound and laminated at one end in the winding axis direction, and is wound and laminated at the other end. A flat wound electrode body 14 having a body exposed portion 16 is produced.

  In this flat wound electrode body 14, the end of the negative electrode active material mixture layer 12 a on the negative electrode core exposed portion 16 side protrudes from the end of the positive electrode active material mixture layer 11 a in the adjacent positive electrode plate 11. And the outer peripheral side is the negative electrode plate 12, and the outermost periphery is a separator. The flat wound electrode body of each embodiment and the flat wound electrode body of the comparative example are different from each other in the pasting state of a tape or the like provided on a separator or a negative electrode plate located on the outermost peripheral side, respectively. However, this difference will not be described here, and the description will be continued assuming that the flat wound electrode body 14 has the same configuration. In addition, the detail of the affixing state of the tape etc. in the flat wound electrode body of each embodiment and the comparative example will be described later.

  On the side of the positive electrode 11, the flat wound electrode body 14 has a plurality of wound and laminated positive electrode core body exposed portions 15 converged to the center side in the thickness direction and further divided into two parts. The positive electrode core exposed portion 15 is focused around ¼, and the positive electrode intermediate member 28 is disposed therebetween (see FIG. 2B). In the positive electrode intermediate member 28, a plurality of conductive intermediate members 28 </ b> B are held on an insulating intermediate member 28 </ b> A made of a resin material. Each conductive intermediate member 28B has a cylindrical shape, and a truncated cone-shaped projection 28C that acts as a projection is formed on the side facing each of the stacked positive electrode core exposed portions 15.

  Similarly, on the negative electrode plate 12 side, a plurality of wound and laminated negative electrode core body exposed portions 16 are converged to the center side in the thickness direction and further divided into two, and the negative electrode core is centered on 1/4 of the electrode body thickness. The body exposed portion 16 is focused, and the negative electrode intermediate member 29 is disposed therebetween (see FIGS. 2B and 2C). In the negative electrode intermediate member 29, a plurality of conductive intermediate members 29B, two in this case, are held on an insulating intermediate member 29A made of a resin material. Each conductive intermediate member 29B has a cylindrical shape, and a truncated cone-shaped projection 29C that acts as a projection is formed on the side facing the negative electrode core exposed portion 16 that is laminated.

  Further, the positive electrode current collectors 17 are disposed on the outermost both sides of the positive electrode core exposed portion 15 located on both sides of the positive electrode intermediate member 28, and the negative electrode core body located on both sides of the negative electrode intermediate member 29. Negative electrode current collectors 19 are respectively disposed on the outermost surfaces on both sides of the exposed portion 16. The conductive intermediate member 28B constituting the positive electrode intermediate member 28 is made of aluminum which is the same material as the positive electrode core body, and the conductive intermediate member 29B constituting the negative electrode intermediate member 29 is made of copper which is the same material as the negative electrode core body. However, each shape may be the same or different.

  Examples of materials that can be used as the insulating intermediate member 28A constituting the positive electrode intermediate member 28 and the insulating intermediate member 29A constituting the negative electrode intermediate member 29 include, for example, polypropylene (PP), polyethylene (PE), polyvinylidene chloride ( PVDC), polyacetal (POM), polyamide (PA), polycarbonate (PC), polyphenylene sulfide (PPS) and the like.

  The flat wound electrode body 14 has a positive electrode core exposed portion 15 wound and laminated at one end in the winding axis direction, and wound and laminated at the other end in the winding axis direction. The negative electrode core exposed portion 16 is welded to the outermost surface in the stacking direction of the positive electrode core exposed portion 15 on which the positive electrode current collector 17 is stacked, and the negative electrode on which the negative electrode current collector 19 is stacked The core body exposed portion 16 is welded to the outermost surface in the stacking direction.

  Resistance welding is performed as follows. For example, on the negative electrode side, a pair of resistance welding electrodes (not shown) are divided into two, each having a frustoconical protrusion 29C formed on both sides of the conductive intermediate member 29B in the main body 19A of the negative electrode current collector 19. The negative electrode core exposed portions 16 are arranged so as to face each other. Then, an appropriate pressing force is applied between the pair of resistance welding electrodes so as to be evenly applied to the negative electrode current collector 19, and resistance welding is performed under predetermined conditions.

  The resistance welding current is obtained, for example, from one resistance welding electrode, the main body portion 19A of one negative electrode current collector 19, the divided negative electrode core exposed portion 16, the conductive intermediate member 29B, and the divided negative electrode core. It flows to the body exposed portion 16, the main body portion 19A of the other negative electrode current collector 19, and the other resistance welding electrode. Thus, the main body portion 19A of one negative electrode current collector 19, the negative electrode core exposed portion 16 divided into two parts, and one end surface of the conductive intermediate member 29B, the other end surface of the conductive intermediate member 29B and 2 Resistance welds are formed between the divided negative electrode core exposed portion 16 and the main body portion 19 </ b> A of the other negative electrode current collector 19.

  The insulating intermediate members 28A and 29A in the positive electrode intermediate member 28 and the negative electrode intermediate member 29 may not be provided, and the number of these conductive intermediate members 28B and 29B may be one according to the required battery output and the like. Or three or more. If two or more conductive intermediate members 28B and 29B are used, two or more conductive intermediate members 28B and 29B are held by insulating intermediate members 28A and 29A made of one resin material. The conductive intermediate members 28B and 29B of each set can be positioned and arranged in a stable state between the core exposed portions on the two divided sides.

  The plurality of positive electrode core exposed portions 15 are stacked and electrically connected to the positive electrode terminal 18 via the positive electrode current collector 17. Similarly, the plurality of negative electrode core exposed portions 16 are stacked to be the negative electrode current collector. The body 19 is electrically connected to the negative terminal 20. The positive electrode terminal 18 and the negative electrode terminal 20 are fixed to the sealing body 23 via insulating members 21 and 22, respectively. The ribs 17B and 19B formed on the positive electrode current collector 17 and the negative electrode current collector 19 are formed integrally with the main body portions 17A and 19A, respectively, and the positive electrode current collector 17 and the negative electrode current collector 19 are formed. Are formed by folding back a part of each of them so as to be substantially vertical at the boundary between the main body portions 17A and 19A.

  Then, after inserting the resin-made insulating sheet 24 around the flat wound electrode body 14 excluding the sealing body 23 side and inserting it into the rectangular exterior body 25, the sealing body 23 is inserted into the opening of the exterior body 25. Fitted. Then, the fitting portion between the sealing body 23 and the exterior body 25 is laser-welded, and a non-aqueous electrolyte solution is produced from the electrolyte solution injection hole 26, thereby producing the square non-aqueous electrolyte secondary batteries of the respective embodiments and comparative examples. It was done. The sealing body 23 is formed with a gas discharge valve 27 as a safety means.

  Here, an example is shown in which the positive electrode current collector 17 and the negative electrode current collector 19 are directly connected to the positive electrode terminal 18 and the negative electrode terminal 20, respectively. However, the positive electrode current collector 17 and the negative electrode current collector 19 are separately provided. It may be connected to the positive terminal 18 or the negative terminal 20 through a conductive member. Moreover, the positive electrode intermediate member 28 and the negative electrode intermediate member 29 may be provided in any one of the positive electrode core exposed portion 15 and the negative electrode core exposed portion 16, and further, the positive electrode intermediate member 28 and the negative electrode intermediate member 29 are used. Without attaching the positive electrode core exposed portion 15 and the negative electrode core exposed portion 16 to each other, the positive electrode current collector 17 and the negative electrode current collector 19 may be attached to each other by resistance welding. Also, it operates when the internal pressure of the battery exceeds a certain value between the positive electrode core exposed portion 15 and the positive electrode terminal 18, and cuts off the conductive path between the positive electrode core exposed portion 15 and the positive electrode terminal 18. A current interruption mechanism can be provided.

Embodiment 1 and Comparative Example
The affixed state of the tape affixed to the separator winding end portion side in the flat wound electrode body 14A of the first embodiment and the flat wound electrode body 14B of the comparative example will be described with reference to FIGS. The flat wound electrode body 14A of Embodiment 1 and the flat wound electrode body 14B of the comparative example are both the positive electrode plate 11 and the negative electrode plate 12, and the positive electrode core exposed portion 15 and the negative electrode plate 12 of the positive electrode plate 11. The cylindrical winding produced by winding through the polyolefin porous separator 13 so that the negative electrode core exposed portion 16 is positioned on the opposite side in the winding axis direction of the electrode body (see FIG. 1). It is produced using an electrode body (not shown).

  In the flat wound electrode body 14A of the first embodiment, in the cylindrical wound electrode body, the separator fixing tape 30A is attached to the outermost peripheral separator 13 and the inner peripheral separator 13 and the separator fixing tape. The length of 30A is made longer than the width of the separator 13, and the end of winding 13a of the separator, the positive electrode core exposed portion 15 and the negative electrode core exposed portion 16 are fixed and then manufactured by press molding. (See FIG. 3). Further, in the flat wound electrode body 14A of the first embodiment, the winding end 13a of the separator is positioned at the curved portion of the flat wound electrode body 14A. In addition, as separator fixing tape 30A, it is preferable to use what uses a polypropylene or polyethylene as a base material.

  In the flat wound electrode body 14B of the comparative example, in the cylindrical wound electrode body, the length of the separator fixing tape 30B is made shorter than the width of the separator 13, and the separator fixing tape 30B is connected to the separator 13 on the outermost periphery side. A material produced by pasting only the separator 13 on the inner peripheral side and press molding the same was used (see FIG. 4). In the flat wound electrode body 14B of the comparative example, the winding end 13a of the separator is positioned at the center of the flat flat portion after press molding.

  Using the flat wound electrode bodies 14A and 14B of the first embodiment and the comparative example manufactured as described above, the prismatic non-aqueous electrolyte secondary corresponding to the first embodiment and the comparative example each having the configuration shown in FIG. A battery was produced. Next, with respect to the obtained prismatic nonaqueous electrolyte secondary battery corresponding to the first embodiment and the comparative example, the floating degree of the outermost negative electrode plate 12 in the flat wound electrode body was measured using a microfocus X-ray CT system manufactured by Shimadzu Corporation. Confirmed using SMX-225CT.

  In the flat wound electrode body, the measurement was performed at a position of 9 mm from the bottom side end of the outer package 25 toward the sealing body 23 and 19 mm from the end of the positive electrode core exposed portion 15 toward the negative electrode core exposed portion 16. Was performed in half scans with 1200 views / 360 ° views and an average count of 8 times. In addition, the height from the bottom part side edge part of the exterior body 25 of a flat winding electrode body to the sealing body 23 side edge part is 82 mm. Further, the measurement result was binarized, and it was determined that the maximum width of the lifted portion of the negative electrode plate 12 on the outermost peripheral side was 2 pixels or less, and that 3 pixels or more were lifted. The results are summarized in Table 1. Moreover, the schematic cross-sectional view of the flat winding electrode body of a comparative example was shown in FIG. In FIG. 5, the configuration other than the outermost negative electrode plate 12 is omitted.

  According to the results shown in Table 1, when the separator fixing tape 30B is applied only from the winding end 13a of the separator 13 positioned on the outermost surface to the separator 13 positioned on the inner peripheral side (comparative example), As shown in FIG. 5, it can be seen that the effect of preventing the negative electrode plate 12 on the outermost peripheral side from being lifted is not achieved. On the other hand, the separator fixing tape 30A is attached from the winding end 13a of the separator 13 located on the outermost surface to the separator 13 located on the inner peripheral side, and is attached to the positive electrode core exposed portion 15 and the negative electrode core exposed portion 16. Is also attached (Embodiment 1), it can be seen that the effect of preventing the negative electrode plate 12 on the outermost peripheral side from being lifted is exhibited.

  That is, it is not only pasted from the winding end 13a of the separator 13 located on the outermost surface to the separator 13 located on the inner peripheral side, but also on the positive electrode core exposed portion 15 and the negative electrode core exposed portion 16 at the same time. The affixed separator fixing tape 30A functions as the lifting prevention means of the present invention. Such an effect is due to the fact that both end portions of the separator fixing tape 30A in the length direction are firmly fixed to the positive electrode core exposed portion 15 and the negative electrode core exposed portion 16; This is probably because the winding end side of 13 is difficult to loosen and the negative electrode plate 12 is difficult to move. Thereby, according to the nonaqueous electrolyte secondary battery of Embodiment 1, since the distance between the negative electrode plate 12 and the positive electrode plate 11 located on the outermost periphery is kept constant, partial discharge unevenness of the battery is caused. The non-aqueous electrolyte secondary battery with high long-term reliability can be obtained.

  In the first embodiment, the separator fixing tape 30A is attached from the winding end 13a of the separator 13 positioned on the outermost surface to the separator 13 positioned on the inner peripheral side, and the positive electrode core exposed portion 15 and the negative electrode core Although the form pasted also to the body exposed part 16 was shown, 30 A of separator fixing tapes should just be stuck to the positive electrode core exposed part 15 at least. The lifting of the negative electrode plate 12 on the outermost peripheral side is likely to occur at the end on the positive electrode core body exposed portion 15 side in the width direction of the negative electrode plate 12. For this reason, if the separator fixing tape 30A is attached to at least the positive electrode core exposed portion 15, it is possible to prevent the separator 13 from winding loose on the positive electrode core exposed portion 15 side. As a result, 12 lifting prevention effects can be obtained. However, as shown in Embodiment 1, it is preferable that the separator fixing tape 30A is attached to the positive electrode core exposed portion 15 and the negative electrode core exposed portion 16 because a greater effect can be obtained. In addition, the length of the separator fixing tape 30 </ b> A can be made smaller than the width of the separator 13.

  In the first embodiment, the outer periphery of the flat wound electrode body 14A has two plane regions facing each other and two curved regions facing each other, and the winding end 13a of the separator is a flat spiral electrode body. It is located at the curved portion of 14A. The separator fixing tape 30A is pasted from the curved portion to the flat area. Since the floating of the negative electrode plate 12 on the outermost peripheral side is likely to occur in the vicinity of the boundary between the curved portion and the planar region, such a configuration can more reliably prevent the negative electrode plate 12 on the outermost peripheral side from lifting. However, such a configuration is not an essential configuration.

  Further, in the first embodiment, the separator fixing tape 30A is disposed at a position corresponding to the boundary between the curved end and the flat end closest to the winding end of the negative electrode plate 12 in the winding direction of the negative electrode plate 12. Although this configuration is not an essential configuration, the configuration can more reliably prevent the outermost negative electrode plate 12 from being lifted. This is because the negative electrode plate 12 is likely to be lifted at the boundary between the curved portion and the flat end portion closest to the end of winding of the negative electrode plate 12 in the winding direction of the negative electrode plate 12. As another form, a tape different from the separator fixing tape 30A is placed at the position corresponding to the boundary between the curved end and the flat end closest to the end of winding of the negative electrode plate 12 in the winding direction of the negative electrode plate 12. It can also be pasted from the outer separator 13 to the positive electrode core exposed portion 15.

  In the first embodiment, the separator fixing tape 30 </ b> A is provided on the bottom side of the exterior body 25 with respect to the bottom side end of the exterior body 25 in the positive electrode current collector 17 and the bottom side end of the exterior body 25 in the negative electrode current collector 19. Is arranged. Therefore, the separator fixing tape 30A does not get in the way when the current collector is connected to the core exposed portion.

[Second to seventh embodiments]
The flat wound electrode bodies 14C to 14I of the second to seventh embodiments provided with means for functioning as the lifting prevention means of the present invention will be described with reference to FIGS.

  As shown in FIG. 6, the flat wound electrode body 14C of the second embodiment is a cylindrical wound electrode body in which the length of the separator fixing tape 30C is longer than the width of the separator 13, After being attached to the end 13a, the positive electrode core exposed portion 15 and the negative electrode core exposed portion 16, press molding is performed so that the winding end 13a of the separator is positioned on the flat portion of the flat wound electrode body 14C. It was produced by. However, the separator winding tape 30C affixed to the positive and negative electrode core exposed portion 15 and the negative electrode core exposed portion 16 is located at the position of the winding end 13a of the separator so that the main body portion 17A of the positive electrode current collector 17 and the negative electrode current collector In order to be in a position that does not overlap the resistance welded portion of the 19 main body portion 19A (see FIG. 2), the position is preferably shifted to the curved portion side of the flat wound electrode body 14C. In this case, the position of the winding end of the outermost negative electrode plate 12 (not shown) is arbitrary.

  Also in the flat wound electrode body 14C of the second embodiment, since both ends in the length direction of the separator fixing tape 30C are firmly fixed to the positive electrode core body exposed portion 15 and the negative electrode core body exposed portion 16, And the winding end 13a side of the separator 13 becomes difficult to loosen at the time of the subsequent battery assembling process, and the negative electrode plate 12 is also difficult to move, and the effect of preventing the negative electrode plate 12 on the outermost peripheral side from being lifted is exhibited.

  As shown in FIG. 7, in the flat wound electrode body 14D of the third embodiment, in the cylindrical wound electrode body, the winding end 13a of the separator is located on the flat portion of the flat wound electrode body 14D. Thus, after press-molding, a pair of separator fixing tapes 30D are pasted over the entire circumference of the flat wound electrode body 14D at two locations. In this case, the position of the winding end of the outermost negative electrode plate 12 (not shown) is arbitrary.

  Also in the flat wound electrode body 14D of the third embodiment, the separator fixing tape 30D fixes both ends in the width direction of the separator 13 over the entire circumference of the separator 13 during the battery assembly process. The end of winding of the separator is difficult to loosen, the negative electrode plate 12 is also difficult to move, and the effect of preventing the negative electrode plate 12 on the outermost peripheral side from being lifted is exhibited. In addition, if the separator fixing tape 30D is pasted over the entire circumference of the flat wound electrode body 14D before press molding, the winding end side of the separator becomes difficult to loosen during pressing.

  As shown in FIG. 8, the flat wound electrode body 14 </ b> E of Embodiment 4 uses a negative electrode plate fixing tape 31 </ b> A having a length shorter than the width of the negative electrode plate 12, and the negative electrode plate fixing tape 31 </ b> A is used as the negative electrode plate 12. Are attached to the end of winding 12b and the separator 13 on the inner periphery thereof, and are press-molded so that the end of winding 12b of the negative electrode plate 12 is located on the flat portion of the flat wound electrode body 14E. In this case, whether or not the separator fixing tape is attached to the winding end 13a of the outermost separator is arbitrary.

  Also in the flat wound electrode body 14E of the fourth embodiment, the winding end 12b of the negative electrode plate 12 is fixed to the inner peripheral side separator 13 by the negative electrode plate fixing tape 31A. The negative electrode plate 12 is also difficult to move during the assembly process, and the effect of preventing the negative electrode plate 12 on the outermost peripheral side from being lifted is exhibited.

  As shown in FIG. 9, the flat wound electrode body 14 </ b> F of the fifth embodiment uses a negative electrode plate fixing tape 31 </ b> B longer than the width of the negative electrode plate 12 in the cylindrical wound electrode body. After the winding end 12b is attached to the inner separator 13 and the positive electrode core exposed portion 15, the winding end 12b of the negative electrode plate 12 is positioned at the flat portion of the flat wound electrode body 14F. It is produced by press molding. In this case, whether or not the separator fixing tape is attached to the winding end 13a of the outermost separator is arbitrary.

  Also in the flat wound electrode body 14F of the fifth embodiment, the winding end 12b of the negative electrode plate 12 is fixed to the inner separator 13 and the positive electrode core exposed portion 15 by the negative electrode plate fixing tape 31B. The negative electrode plate 12 is also difficult to move during pressing and the subsequent battery assembly process, and the effect of preventing the negative electrode plate 12 on the outermost peripheral side from being lifted is exhibited. In this case, the position of the winding end 12b of the negative electrode plate 12 is such that the negative electrode plate fixing tape 31B attached to the positive and negative electrode core exposed portion 15 is the main body portion 17A of the positive electrode current collector 17 and the main body of the negative electrode current collector 19. In order to make it a position which does not overlap with the resistance welding part of part 19A (refer to Drawing 2), it is preferred to make it a position shifted to the curved part side of flat winding electrode body 14C.

  In the flat wound electrode body 14G of the sixth embodiment, after the cylindrical wound electrode body is press-molded, as shown in FIG. 10, the main body portion 17A of the positive electrode current collector 17 is formed on the positive electrode core exposed portion 15. The anti-spatter tape 32 as an insulating film that also serves to prevent spatter scattering and the fixing of the negative electrode plate 12 is applied to the separator 13 on the outermost surface from the positive electrode core exposed portion 15.

  In the flat wound electrode body 14G of the sixth embodiment, the outermost peripheral negative electrode plate 12 is pressed against the center side of the flat wound electrode body 14G by the anti-sputter tape 32. The effect of preventing lifting is exhibited. In this case, whether or not the separator fixing tape is attached to the winding end 13a of the outermost separator is arbitrary. The anti-spatter tape 32 is an insulating member, but an opening may be provided at a position corresponding to the connecting portion between the positive electrode core exposed portion 15 and the positive electrode current collector 17. As the anti-sputtering tape 32, it is preferable to use a tape made of a thermoplastic resin.

  In the sixth embodiment, the anti-sputtering tape 32 is used as the insulating film, and the anti-sputtering tape 32 is applied from the positive electrode core exposed portion 15 to the outermost separator 13. Although such a form is preferable, the insulating film does not necessarily have to be attached to the outermost separator 13, and the negative electrode plate 12 is placed on the center side of the flat wound electrode body 14G by the elastic force of the insulating film. It can also be pressed.

  As shown in FIG. 11, the flat wound electrode body 14H of the seventh embodiment is the outermost periphery of the flat wound electrode body having the same configuration as the flat wound electrode body 14B of the comparative example (see FIG. 4). The side is covered with a heat-shrinkable film 33 throughout. The heat-shrinkable film 33 is produced by forming the flat wound electrode body 14B having the configuration shown in FIG. 4 and then winding and heating the heat-shrinkable film 33. In the flat wound electrode body 14H of the seventh embodiment, the heat-shrinkable film 33 is used to form the negative electrode plate 12 with respect to the flat wound electrode body 14B of the comparative example that does not have the effect of preventing the negative electrode plate 12 from being lifted. It becomes possible to impart a lifting prevention effect. In addition, the separator fixing tape 30D in the flat wound electrode body 14H is not necessarily a necessary configuration and may be omitted.

DESCRIPTION OF SYMBOLS 10 ... Square nonaqueous electrolyte secondary battery 11 ... Positive electrode plate 11a ... Positive electrode active material mixture layer 12 ... Negative electrode plate 12a ... Negative electrode active material mixture layer 12b ... End of winding of negative electrode plate 13 ... Separator 13a ... Winding of separator Ends 14, 14A to 14I ... Flat wound electrode body 15 ... Positive electrode core exposed portion 16 ... Negative electrode core exposed portion 17 ... Positive electrode current collector 17A ... Main body portion 17B ... Rib 19 ... Negative electrode current collector 19A ... Main body Part 19B ... Rib 20 ... Negative electrode terminal 21, 22 ... Insulating member 23 ... Sealing body 24 ... Insulating sheet 25 ... Exterior body 26 ... Electrolyte injection hole 27 ... Gas discharge valve 28 ... Positive electrode intermediate member 28A ... Insulating intermediate member 28B ... Conductive intermediate member 28C ... Protrusion 29 ... Negative electrode intermediate member 29A ... Insulating intermediate member 29B ... Conductive intermediate member
29C ... Projection 30A-30D ... Separator fixing tape 31A, 31B ... Negative electrode plate fixing tape 32 ... Spatter prevention tape 33 ... Heat shrinkable film

Claims (6)

A flat winding in which a positive electrode plate having a positive electrode active material mixture layer formed on a positive electrode core and a negative electrode plate having a negative electrode active material mixture layer formed on a negative electrode core are wound through a separator. An electrode body,
A wound positive electrode core exposed portion is formed at one end of the flat wound electrode body,
A wound negative electrode core exposed portion is formed at the other end of the flat wound electrode body,
The wound positive electrode core exposed portion is converged and a positive electrode current collector is connected,
The wound negative electrode core exposed part is converged and a negative electrode current collector is connected,
The end of winding of the negative electrode plate is located on the outer peripheral side of the flat wound electrode body than the end of winding of the positive electrode plate,
The outer periphery of the flat wound electrode body has two opposing planar regions and two opposing curved regions,
The separator is located on the outermost surface of the flat wound electrode body,
The winding end of the separator is located in the curved region,
In the outermost peripheral region of the negative electrode plate, a tape that prevents the separator from being lifted from the separator located on the inner peripheral side of the outermost peripheral region of the negative electrode plate is disposed from the end of winding of the separator to the end of winding of the separator. It is pasted over the separator located on the peripheral side and from the curved region to the planar region, and extends on the positive electrode core exposed portion, and is also pasted on the positive electrode core exposed portion. Yes,
Secondary battery.   The secondary battery according to claim 1, wherein the tape extends on the negative electrode core exposed portion and is also attached to the negative electrode core exposed portion.   The secondary tape according to claim 1 or 2, wherein the tape is attached at a position corresponding to a boundary portion between a curved portion and a flat end portion closest to a winding end of the negative electrode plate in a winding direction of the negative electrode plate. battery. A bottomed cylindrical exterior body having an opening; and a sealing body for sealing the opening. The flat wound electrode body has a winding axis direction of the flat wound electrode body that is the bottom of the exterior body. Is stored in the exterior body so as to be parallel to
The said tape is arrange | positioned in the said bottom part side rather than the bottom part side edge part of the said exterior body in the said negative electrode electrical power collector, and the bottom part side edge part of the said exterior body in the said negative electrode collector. A secondary battery according to any one of the above.   The positive electrode current collector is connected to the outermost surface of the wound positive electrode core exposed portion, and the negative electrode current collector is connected to the outermost surface of the wound negative electrode core exposed portion, The secondary battery according to claim 1. Between the curved portion closest to the winding end of the negative electrode plate in the winding direction of the negative electrode plate and the boundary portion between the flat end portions, the winding is performed from the separator located on the outermost surface of the flat wound electrode body. The secondary battery according to claim 1, wherein the tape is attached to the outermost surface of the exposed positive electrode core body.

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