JP5501270B2 - Battery using coated electrode group - Google Patents

Description

  The present invention relates to a secondary battery using a coated electrode group.

  In recent years, technological development and commercialization of electric vehicles and hybrid vehicles have been advanced from the viewpoint of suppressing greenhouse gas emissions. As a battery suitable for such an application, a lithium ion secondary battery having a high energy density as compared with other battery systems has attracted particular attention.

  Parts and mounted devices used in automobiles are exposed to intermittent vibrations and impacts due to road surface irregularities during traveling, and this is the same in electric cars and hybrid cars. Therefore, sufficient vibration resistance is also required for batteries mounted on electric vehicles and hybrid vehicles.

  Problems that may occur inside the battery when vibration is applied from the outside to the battery include a break in the conductive path formed by welding or the like, a break in the current tab, and the like. These defects lead to an increase in the internal resistance of the battery and a disconnection of the conductive path.

  Another problem is misalignment of the positive electrode, the negative electrode, and the separator. If the relative positions of the positive electrode and the negative electrode are shifted, the facing area of the positive and negative electrodes changes, so that the battery capacity changes. Further, when the relative position of the separator is shifted and the positive and negative electrodes face each other directly, there is a possibility that an internal short circuit occurs at this portion.

  For the purpose of improving the vibration resistance of the battery, Patent Document 1 discloses that an electrode group is formed by forming an annular groove portion that is not easily inserted into the outermost peripheral electrode plate near the center of the battery outer can or at the upper and lower portions. A technique for pressing and fixing is disclosed. Patent Document 2 proposes a method of winding a resin sheet that absorbs a nonaqueous electrolyte and expands together with a positive electrode, a negative electrode, and a separator. According to this method, since the resin sheet absorbs the nonaqueous electrolytic solution and expands inside the battery, the electrode group is pressed and fixed.

Japanese Patent Laid-Open No. 9-293529 JP 2001-52755 A

  The technique described in Patent Document 1 obtains an effect by inserting the groove formed in the battery outer can into the outermost peripheral electrode plate. However, in the case of adopting a thin electrode due to the necessity of reducing the internal resistance in a high output type battery or the like, as the electrode is made thinner, it becomes difficult to make the groove portion difficult to insert only the outermost peripheral plate, Other electrodes and separators may be deformed and damaged.

  In the method described in Patent Document 2, since the resin sheet is interposed in the electrode group, the ratio of the positive electrode and the negative electrode in the electrode group decreases. For this reason, there exists a possibility that the electrical capacity of a battery may reduce.

  The present invention has been made in view of such problems, and even when an external force such as vibration is applied to the battery, the relative displacement between the positive electrode, the negative electrode, and the separator is reduced without reducing the electric capacity. It aims at providing the battery which can suppress and maintain the positional relationship of a positive / negative electrode and a separator.

  The battery using the coated electrode group according to the present invention has the following characteristics.

  A positive electrode in which a coating layer containing a positive electrode active material is formed on a current collector, a negative electrode in which a coating layer containing a negative electrode active material is formed on a current collector, the positive electrode and the negative electrode In a battery using a coating-type electrode group including a separator that is electrically isolated, the coating layer of one of the positive electrode and the negative electrode has a predetermined length in one side and the other electrode The coating layer is longer than the length in the one side direction, and at least part of the end region at both ends in the one side direction is provided with a thick portion having a thickness greater than the central portion in the one side direction. . The other electrode is positioned between the thick portion provided at one end of the one-side direction of the coating layer of the one electrode and the thick portion provided at the other end.

  According to the present invention, even when an external force such as vibration is applied to the battery, the relative positional deviation between the positive electrode, the negative electrode, and the separator is suppressed without reducing the electric capacity, and the positional relationship between the positive and negative electrodes and the separator is changed. A battery that can be maintained can be provided.

It is a schematic diagram of the cross section containing the Z axis | shaft parallel to the Z axis | shaft of the battery using a coating type winding type electrode group. FIG. 3 is a schematic diagram showing a cross section parallel to the Z axis of a wound electrode group in Example 1. It is the schematic diagram which expanded and showed the S edge part of the winding type electrode group. It is the schematic diagram which expanded and showed the T edge part of the winding type electrode group. 6 is a schematic diagram showing a cross section of the wound electrode group in Example 2 parallel to the Z axis. FIG. FIG. 6 is a schematic diagram showing a cross section parallel to the Z axis of a wound electrode group in Example 3. It is a structure schematic diagram of the square battery using a flat wound electrode group. It is a schematic diagram of the cross section in the DZ plane of the square battery using a flat winding type electrode group. It is a schematic diagram which shows the application layer of the electrode A, and its thick part. It is another schematic diagram which shows the application layer of the electrode A, and its thick part. It is another schematic diagram which shows the application layer of the electrode A, and its thick part. It is another schematic diagram which shows the application layer of the electrode A, and its thick part. 10 is a diagram illustrating a first example of a configuration of a stacked electrode group in Example 5. FIG. 10 is a diagram illustrating a second example of the configuration of the stacked electrode group in Example 5. FIG. FIG. 10 is a diagram showing a third example of the configuration of the stacked electrode group in Example 5. 10 is a diagram illustrating a fourth example of the configuration of the stacked electrode group in Example 5. FIG. FIG. 10 is a diagram showing a fifth example of the configuration of the stacked electrode group in Example 5.

  The battery according to the present invention has an electrode group composed of a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate and the negative electrode plate are made of a coated electrode having a current collector and a coating layer (active material coating layer). The coating layer is formed by applying a slurry obtained by kneading an active material, a suitable solvent, a binder and the like onto a metal foil as a current collector and drying it. By optimizing the cross-sectional shape (thickness) of the coating layer of the coating-type electrode, even when an external force such as vibration is applied to the battery, the relative displacement between the positive electrode, the negative electrode, and the separator can be suppressed. By maintaining the positional relationship among the positive electrode plate, the negative electrode plate, and the separator, the structural soundness of the electrode can be improved.

  The electrode group of the battery according to the present invention has the following structure. In either one of the positive electrode and the negative electrode (hereinafter referred to as “electrode A”), the length of the coating layer in a predetermined one-side direction (hereinafter referred to as “Z-axis direction”) of the electrode plate is The length of the other electrode (hereinafter referred to as “electrode B”) is longer than the length of the coating layer in the Z-axis direction. Furthermore, the electrode A has a portion (hereinafter referred to as a “thick portion”) in which at least a part of the end regions at both ends in the Z-axis direction is thicker than the other portion (the central portion in the Z-axis direction). Provided). Further, the electrode B is disposed between the thick part at one end of the electrode A in the Z-axis direction and the thick part at the other end. The electrode group is formed by interposing a separator between the electrode A and the electrode B.

  The Z-axis direction (predetermined one side direction of the electrode plate) can be determined in a direction in which the positive electrode electrode, the negative electrode electrode, and the separator are likely to be displaced, and specifically can be determined according to the form of the electrode group. it can. For example, when the electrode group is a wound type in which a positive electrode and a negative electrode are wound through a separator, the winding axis direction is the Z-axis direction. When the electrode group is a stacked type in which a plurality of positive electrodes and negative electrodes are stacked via a separator, any one side direction of the electrode plate is defined as the Z-axis direction. When the electrode group is a laminated type, the Z-axis direction may be changed for each electrode plate (positive electrode and negative electrode) to be laminated so that the thick portions are not concentrated in one direction.

  In the battery according to the present invention, the relative displacement between the positive electrode, the negative electrode, and the separator can be suppressed even when an external force such as vibration is applied without causing deterioration of characteristics such as electric capacity and reliability, and positive and negative electrodes, By maintaining the positional relationship of the separator, it is possible to improve the structural integrity of the electrode.

  The present invention is applicable to, for example, a battery using a wound electrode group or a battery using a stacked electrode group, regardless of the method of forming the electrode group.

  In addition, in the battery using the coating type electrode group according to the present invention, the effect of improving the structural integrity of the electrode group is obtained, but it is clear that this effect does not depend on the polarity of the electrode A and the electrode B. . Accordingly, either the electrode A or the electrode B may be a positive electrode or a negative electrode, and the polarity can be appropriately determined according to the requirements in battery design.

  In this example, a battery using a wound electrode group will be described as an example of a coating-type electrode group.

  FIG. 1 is a schematic view of a cross section including a winding axis parallel to a winding axis of a battery using a coating-type wound electrode group according to the first embodiment of the present invention. In the first embodiment, a cylindrical battery using a cylindrical wound electrode group as an electrode group is handled. The winding axis direction is used as the Z-axis direction (a predetermined one side direction of the electrode plate).

  A cylindrical wound electrode group 100 includes a belt-like positive electrode plate 120, a belt-like negative electrode plate 130, and a belt-like separator 140 (partially enlarged view of FIG. 1) using a core material called a shaft core 110 as a winding shaft. Are formed concentrically. The positive electrode current collector lead 210 protrudes from the positive electrode plate 120 to one side in the Z-axis direction, and the negative electrode current collector lead 220 protrudes from the negative electrode plate 130 to the other side in the Z-axis direction (opposite to the positive electrode current collector lead 210). Each of them constitutes a current collecting lead group of a positive electrode and a negative electrode.

  The positive electrode current collecting lead 210 is connected to the positive electrode connecting plate 216 via the positive electrode current collecting ring 215, and the positive electrode connecting plate 216 is connected to the positive electrode terminal cap 310. The negative electrode current collector lead 220 is connected to the negative electrode connection plate 226 through the negative electrode current collector ring 225.

  The wound electrode group 100 is housed in a battery outer can 300. At this time, the negative electrode connection plate 226 is connected to the battery outer can 300. The battery outer can 300 is sealed by the positive electrode terminal cap 310 via the gasket 320 after the nonaqueous electrolyte is injected.

  As shown in the partially enlarged view of FIG. 1, the positive electrode plate 120 includes a positive electrode current collector 126 and a positive electrode active material coating layer (coating layer) 125 formed on both surfaces of the positive electrode current collector 126. The negative electrode plate 130 includes a negative electrode current collector 136 and a negative electrode active material coating layer (coating layer) 135 formed on both surfaces of the negative electrode current collector 136.

  FIG. 2 is a schematic diagram showing a cross section of the wound electrode group 100 parallel to the Z axis (winding axis). In FIG. 2, the positional relationship among the electrode A (one of the positive electrode and the negative electrode) 10, the electrode B (the other electrode) 20, and the separator 30 is schematically shown.

  In the electrode A10 and the electrode B20, a coating layer is formed on both surfaces of a part of the current collector, and a portion where the coating layer is not formed (a portion where the current collector is exposed) is a current collecting lead 15 respectively. And a current collecting lead 25. The current collecting lead 15 of the electrode A10 projects to one side in the Z-axis direction, and the current collecting lead 25 of the electrode B20 projects to the other side in the Z-axis direction (opposite to the current collecting lead 15 of the electrode A10). It constitutes a current collecting lead group of poles.

  As shown in FIG. 2, the length of the coating layer in the Z-axis direction of the electrode A10 is longer than the length of the coating layer in the Z-axis direction of the electrode B20. Further, in the coating layer of the electrode A10, a portion (thick portion 40) where the thickness of the coating layer is thicker than other portions (center portion in the Z-axis direction) in at least a part of the end regions at both ends in the Z-axis direction. ) Is provided. The thick part 40 may be provided on both sides of the coating layer of the electrode A10 or may be provided only on one side. You may change the thickness of the thick part 40 for every application layer of electrode A10. Moreover, when providing the thick part 40 on both surfaces of the application layer of electrode A10, you may change the thickness of the thick part 40 on both surfaces.

  The electrode B20 is disposed between the thick part 40 at one end and the thick part 40 at the other end of the electrode A10 in the Z-axis direction. That is, the wound electrode group 100 is formed through the separator 30 so that the electrode B20 does not overlap the thick portion 40 of the electrode A10.

  The thickness of the thick part 40 does not need to be uniform. Further, the thickness portion 40 at one end in the Z-axis direction and the thickness portion 40 at the other end may not have the same length in the Z-axis direction.

  The thick part 40 will be described with reference to FIGS. 9A to 9D. 9A to 9D are schematic views showing the coating layer 11 of the electrode A10 and its thick part 40 when the electrode A10 is developed, and an arrangement example of the thick part 40 is shown.

  In FIG. 9A, the thick portion 40 is in the entire end region, that is, in the direction perpendicular to the Z axis at both ends in the Z-axis direction of the coating layer 11 (the longitudinal direction of the coating layer 11, that is, the left-right direction in FIG. 9A). Are provided continuously.

  In FIG. 9B, the thick portions 40 are provided at both ends of the coating layer 11 in the Z-axis direction, scattered in a part of the end region, that is, in a direction perpendicular to the Z-axis. Further, the thick portion 40 at one end in the Z-axis direction and the thick portion 40 at the other end are provided at corresponding positions in the Z-axis direction. The length of each of the scattered thick portions 40 in the Z-axis direction and the length in the direction perpendicular to the Z-axis may not be equal.

  Also in FIG. 9C, the thick portions 40 are provided at both ends of the coating layer 11 in the Z-axis direction, scattered in a part of the end region, that is, in a direction perpendicular to the Z-axis. However, the positions of the thick part 40 at one end in the Z-axis direction and the thick part 40 at the other end do not correspond to the Z-axis direction.

  The thick portions 40 are provided in end regions at both ends of the coating layer 11 in the Z-axis direction, and extend along the sides at both ends of the coating layer 11 in the Z-axis direction (the longitudinal direction of the coating layer 11, that is, the left-right direction in FIG. 9A). Side) may not be included. In FIG. 9D, as in FIG. 9A, the thick portion 40 is provided at both ends of the coating layer 11 in the Z-axis direction, continuously over the entire end region, that is, in a direction perpendicular to the Z-axis. . However, the thick portion 40 does not include sides on both ends of the coating layer 11 in the Z-axis direction. Even when the thick portions 40 are provided in the direction perpendicular to the Z-axis of the coating layer 11 as shown in FIGS. 9B and 9C, the sides at both ends of the coating layer 11 in the Z-axis direction are formed. It does not have to be included.

  Although not shown, the thick portion 40 is formed so that one end of the coating layer 11 in the Z-axis direction includes the side of the coating layer 11 at one end and does not include the side of the coating layer 11 at the other end. It may be provided.

  However, since the electrode B20 is disposed between the thick part 40 at one end of the electrode A10 in the Z-axis direction and the thick part 40 at the other end, the area where the electrode B20 and the electrode A10 face each other (the area causing the battery reaction) is taken into consideration. Then, as shown in FIGS. 9A to 9C, it is preferable to provide the thick portion 40 so as to include sides on both ends of the coating layer 11 in the Z-axis direction.

A desirable thickness of the thick portion 40 will be described with reference to FIGS. 3 and 4. 3 and 4, the thickness of the thick portion 40 (thickness represented by S ₅ , S ₆ , T ₅ , and T ₆ described later) is not provided with the thick portion 40 of the coating layer. It is a value indicating how thick the coating layer is compared with the portion (the central portion in the Z-axis direction).

FIG. 3 is an enlarged view of the end of the wound electrode group 100 in the Z-axis direction from which the current collecting lead 25 of the electrode B20 protrudes (hereinafter referred to as “S end”). It is a schematic diagram. 3, the distance between the electrodes A10 at a portion not provided with the thick portion _{S 1} a (opposing distance of the electrodes A10), thick portion 40a, the distance between the electrodes A10 in 40b (the opposing distance of the electrodes A10) _S 2, the thickness of the electrode B20 _{S 3,} the thickness of the current collector lead 25 of the electrode B20 to _{S 4.} The current collector lead 25 is a portion where the current collector of the electrode B20 is exposed. Further, the thickness of the thick portion 40a of the electrode A10 _{S 5,} the thickness of the thick portion 40b and _{S 6.} S ₁ is also the total thickness of the electrode B 20 and the two separators 30.

At this time, it is desirable to configure the thick portion 40 so as to satisfy the relationship of Formula 1.
S ₁ −S ₂ ≦ S ₃ −S ₄ (Formula 1)
Relationship S ₁ and _{S 2} and _{S 3} and _{S 4} does not satisfy the formula 1 and _{(S 1 -S 2> S 3} -S 4), S 3 <S 1 -S 2 + S 4 _becomes, S 1 -S _{Since 2} = S ₅ + S ₆ , S ₃ <S ₅ + S ₆ + S ₄ is satisfied. That is, the sum of the thicknesses 40a and 40b of the electrode A10 and the thickness of the current collecting lead 25 of the electrode B20 (S ₅ + S ₆ + S ₄ ) exceeds the thickness (S ₃ ) of the electrode B20. End up. This is a state in which the thickness of the thick portion 40 (the sum of the thicknesses of the thick portion 40a and the thick portion 40b) is too thick. If there are many portions that do not satisfy Formula 1, the diameter of the wound electrode group 100 is significantly larger than the diameter near the center in the Z-axis direction at the S end, and the shape of the wound electrode group 100 is The inconvenience of distortion occurs.

FIG. 4 is an enlarged view of the end of the wound electrode group 100 in the Z-axis direction from which the current collecting lead 15 of the electrode A10 protrudes (hereinafter referred to as “T end”). It is a schematic diagram. 4, the distance between the electrodes A10 at a portion not provided with the thick portion _{T 1} (opposing distance of the electrodes A10), thick portion 40c, the distance between the electrodes A10 in 40d and _T 2 (opposing distance of the electrodes A10), the thickness of the electrode B20 _{T 3,} the thickness of the current collector lead 25 of the electrode B20 and _{T 4.} Further, the thickness of the thick portion 40c of the electrode A10 _{T 5,} the thickness of the thick portion 40d and _{T 6.} T ₁ is also the total thickness of the electrode B 20 and the two separators 30.

At this time, it is desirable to configure the thick portion 40 so as to satisfy the relationship of Formula 2.
T ₁ −T ₂ ≦ T ₃ (Formula 2)
Relationship T ₁ and _{T 2} and _{T 3} does not satisfy the formula 2 and _{(T 1 -T 2> T 3} ), since it is _{T 1 -T 2 = T 5 +} T 6, and _{T 3 <T} 5 + T ₆ Become. That is, the sum (T ₅ + T ₆ ) of the thicknesses 40c and 40d of the electrode A10 exceeds the thickness (T ₃ ) of the electrode B20. This is a state where the thickness of the thick portion 40 (the sum of the thicknesses of the thick portion 40c and the thick portion 40d) is too thick. If there are many portions that do not satisfy Formula 2, the diameter of the wound electrode group 100 is significantly larger than the diameter near the center in the Z-axis direction at the T end, and the shape of the wound electrode group 100 is The inconvenience of distortion occurs.

  As an example of a method for forming the thick part of the electrode A, in the step of forming a coating layer on the current collector of the electrode A, the amount of slurry applied in the portion that becomes the end region in the Z-axis direction when the electrode A is completed And increasing the thickness of the coating layer. For example, when the coating layer is formed by the comma coating method, if the diameter of the rod knife is partially reduced, the clearance between the rod knife and the roll at that part becomes larger than the other parts, and the amount of slurry applied is increased. can do. That is, if the diameter of the rod knife is appropriately reduced corresponding to the portion where the thick portion is to be provided in the electrode A, the thick portion can be formed in a desired form.

  In general, in the production process of a coating type electrode, there is a step of smoothing the coating layer surface and increasing the coating layer density by roll pressing after the coating layer is formed. Even if it goes through such a process, if the amount of slurry applied in the portion that becomes the end region in the Z-axis direction when the electrode A is completed as described above is increased, the spring back even after pressing Thus, a thick part is formed.

  Further, as another example of the method for forming the thick part of the electrode A, in the electrode roll pressing step after the coating layer is formed on the current collector of the electrode A, the end area of the electrode A of the press roll is applied. A method of forming a thick portion by reducing the diameter of the contacting portion smaller than other portions and reducing the applied pressing pressure can be mentioned. In this method, it is not always necessary to increase the amount of slurry applied in the end region of the coating layer of the electrode A before performing the roll press step.

In the wound electrode group according to the present example, the total thickness of the electrode B and the two separators is larger than the distance (S ₂ shown in FIG. 3) where the thick portions of the electrode A face each other at the S end. (S ₁ shown in FIG. 3) is thicker, and at the T end, the total of the electrode B and the two separators is larger than the distance (T ₂ shown in FIG. 4) where the thick parts of the electrode A face each other. The thickness (T ₁ shown in FIG. 4) is thicker. Therefore, even when vibration or the like is applied, the displacement of the electrode B is blocked by the thick part of the electrode A, and similarly, the displacement of the electrode A is blocked by the electrode B.

  Therefore, in the battery using the wound electrode group according to the present embodiment, even when an external force such as vibration is applied, the winding electrode group is unwound (relative displacement between the positive electrode, the negative electrode, and the separator). Is suppressed, the positional relationship between the positive and negative electrodes and the separator can be maintained, and the structural integrity of the wound electrode can be improved.

  The method for forming the thick portion of the electrode A is not limited to the method exemplified in the above description. It is obvious that the present invention does not depend on the method of forming the thick portion as long as the thick portion is formed in accordance with the spirit of the present invention.

  Further, the shape and arrangement of the thick part of the electrode A are not limited to those exemplified in the above description. Obviously, the thick part of the electrode A may be in any shape or arrangement as long as it conforms to the spirit of the present invention.

  The thick part of the electrode A exemplified in the above description is formed so as to increase the thickness of the coating layer in both end regions on both sides of the current collector of the electrode A. As long as the relationship is satisfied, the thickness of the coating layer on each surface and each end region of the current collector need not be the same.

  In the present embodiment, as in the first embodiment, a battery using a cylindrical wound electrode group as an application type electrode group will be described as an example. As in the first embodiment, the winding axis direction is used as the Z-axis direction (a predetermined one-side direction of the electrode plate). Further, the S end and the T end also refer to the same parts as in the first embodiment.

  FIG. 5 is a schematic diagram showing a cross section of the wound electrode group 100 parallel to the Z-axis. 5, the same reference numerals as those in FIG. 2 denote the same or common elements as those in FIG. In the present embodiment, the thick portion 40 is provided only on one side of the coating layer of the electrode A10. That is, on one side of the coating layer of the electrode A10, thick portions are provided in the end region at both ends in the Z-axis direction by making the coating layer thicker than other portions (center portion in the Z-axis direction). Further, the thick portion is formed so that the relationship of Formula 1 is satisfied at the S end and the relationship of Formula 2 is satisfied at the T end. If it does in this way, the effect similar to 1st Embodiment will be acquired also in this embodiment.

  In the present embodiment, as in the first embodiment, a battery using a cylindrical wound electrode group as an application type electrode group will be described as an example. As in the first embodiment, the winding axis direction is used as the Z-axis direction (a predetermined one-side direction of the electrode plate). Further, the S end and the T end also refer to the same parts as in the first embodiment.

  FIG. 6 is a schematic diagram showing a cross section of the wound electrode group 100 parallel to the Z-axis. 6, the same reference numerals as those in FIG. 2 denote the same or common elements as those in FIG. In this embodiment, the thick part 40 is provided on both surfaces of the coating layer of the electrode A10. However, the thick portion 40 is provided only in one end region in the Z-axis direction on one surface of the coating layer, and is provided only in the end region in the other end in the Z-axis direction on the other surface of the coating layer. Yes. That is, in the coating layer of the electrode A10, a thick part is provided in the end region at one end in the Z-axis direction on one surface so that the thickness of the coating layer is thicker than that of the other part (center portion in the Z-axis direction). In the other end face region of the other end in the Z-axis direction, a thick portion is provided by making the thickness of the coating layer thicker than other portions (center portion in the Z-axis direction). Further, the thick portion is formed so that the relationship of Formula 1 is satisfied at the S end and the relationship of Formula 2 is satisfied at the T end. If it does in this way, the effect similar to 1st Embodiment will be acquired also in this embodiment.

  The present invention provides an effect of improving the structural soundness of a battery using a coated electrode group by providing a thick portion in the end region of the coated layer of the coated electrode to define the relative position of the electrode group. It is. Therefore, the effect of the present invention can be obtained not only in a cylindrical battery using a cylindrical wound electrode group but also in a rectangular battery using a flat wound electrode group.

  FIG. 7 is a structural schematic diagram of a prismatic battery using a flat wound electrode group in the present embodiment. The flat wound electrode group 500 is configured by winding a belt-like positive electrode plate, a belt-like negative electrode plate, and a belt-like separator into a flat shape. The positive electrode current collector lead of the positive electrode plate is connected to the positive electrode current collector plate 610 via the connection portion 615, and the negative electrode current collector lead of the negative electrode plate is connected to the negative electrode current collector plate 630 via the connection portion 635. . The flat wound electrode group 500, the positive electrode current collector plate 610, and the negative electrode current collector plate 630 are accommodated in the battery outer can 700 via the insulating sheet 710. In the present embodiment, the flat wound electrode group 500 is housed in the battery outer can 700 in a state where the winding axis is directed in the horizontal direction (left-right direction in FIG. 7).

  Also in this embodiment, the winding axis direction is the Z-axis direction. Further, the thickness direction of the flat wound electrode group 500 (the short side direction of the cross section perpendicular to the winding axis of the flat wound electrode group 500) is the D axis, and the direction perpendicular to the Z axis and the D axis. The long axis direction of the cross section perpendicular to the winding axis of the flat wound electrode group 500 is defined as the H axis.

  After the flat wound electrode group 500, the positive electrode current collector plate 610 and the negative electrode current collector plate 630 are accommodated in the battery outer can 700, a non-aqueous electrolyte is injected and sealed by the battery upper lid 750. The battery top cover 750 includes a positive electrode terminal 620, a negative electrode terminal 640, a liquid filling plug 770, and a pressure release valve 760. The positive electrode terminal 620 and the negative electrode terminal 640 are connected to the positive electrode current collector plate 610 and the negative electrode current collector plate 630, respectively. The non-aqueous electrolyte is injected from the injection plug 770 into the battery outer can 700. The pressure release valve 760 is used to release the internal pressure when the internal pressure of the battery outer can 700 increases.

  FIG. 8 shows a connecting portion 615 between a positive current collecting lead and a positive current collecting plate and a connecting portion 635 between a negative current collecting lead and a negative current collecting plate of a rectangular battery using the flat wound electrode group in this embodiment. It is a schematic diagram of the cross section in the plane (DZ plane) to cross. As described above, the flat wound electrode group 500, the positive electrode current collector plate 610, and the negative electrode current collector plate 630 are accommodated in the battery outer can 700 via the insulating sheet 710.

  The flat wound electrode group 500 includes a strip-shaped positive electrode plate 120, a strip-shaped negative electrode plate 130, and a strip-shaped separator 140 (see the partially enlarged view of FIG. 8), with a flat shaft core 510 as a winding axis. It is formed by being wound to have a flat shape. The positive electrode current collector lead 612 protrudes from the positive electrode plate 120 to one side (−Z direction) in the Z-axis direction, and the negative electrode current collector lead 632 protrudes from the negative electrode plate 130 to the other side (+ Z direction), respectively. It constitutes a current collecting lead group of a positive electrode and a negative electrode. The positive electrode current collecting lead 612 is connected to the positive electrode connecting plate 610 via the connection portion 615, and the negative electrode current collecting lead 632 is connected to the negative electrode connecting plate 630 via the connection portion 635.

  As shown in the partially enlarged view of FIG. 8, the positive electrode plate 120 includes a positive electrode current collector 126 and a positive electrode active material coating layer (coating layer) 125 formed on both surfaces of the positive electrode current collector 126. The negative electrode plate 130 includes a negative electrode current collector 136 and a negative electrode active material coating layer (coating layer) 135 formed on both surfaces of the negative electrode current collector 136.

  As described above, the basic structure of the flat wound electrode group is the same as the structure of the cylindrical wound electrode group described in the first to third embodiments. Therefore, also in the flat wound electrode group, the length of the coating layer in the winding axis direction (Z-axis direction) is set to the other electrode (electrode A) of either the positive electrode or the negative electrode (electrode A). The electrode B) is longer than the length of the coating layer in the Z-axis direction, and a thick portion is provided in at least a part of both end regions of the coating layer of the electrode A in the Z-axis direction. It can arrange | position between the thick part of the one end of a direction, and the thick part of the other end.

  By adopting such a configuration, even in the battery using the flat wound electrode group according to the present embodiment, the winding displacement of the wound electrode group (relative displacement between the positive electrode, the negative electrode, and the separator) is reduced. It can suppress and can maintain the positional relationship of a positive / negative electrode and a separator, and can improve the structural soundness of a wound-type electrode.

  In Example 4, a rectangular battery using a wound flat electrode group has been described. However, the present invention can also be applied to a rectangular battery using a stacked electrode group. The present invention provides an effect of improving the structural soundness of a battery using a coated electrode group by providing a thick portion in the end region of the coated layer of the coated electrode to define the relative position of the electrode group. It is. Therefore, even in a battery using a stacked electrode group, the same effect as that of a battery using a wound electrode group can be obtained.

  10A to 10E show examples of the configuration of the stacked electrode group according to the present invention. In FIGS. 10A to 10E, the separator 30 existing between the electrode A10 and the electrode B20 is omitted and not shown.

  10A to 10C, the electrode A10 is provided with a thick portion 40 in the end region in the Z-axis direction of the coating layer, and the electrode B20 is different from the thick portion 40 at one end of the electrode A10 in the Z-axis direction. It arrange | positions between the thick parts 40 of an edge. In FIG. 10A, the current collecting lead 15 of the electrode A10 and the current collecting lead 25 of the electrode B protrude from both ends of the electrode A10 in the Z-axis direction. In FIG. 10B, the current collecting lead 15 of the electrode A10 and the current collecting lead 25 of the electrode B protrude from both ends of the electrode A10 in the W-axis direction. The W-axis direction is a direction perpendicular to the Z-axis direction in the plane of the electrode A10. Further, as shown in FIG. 10C, the current collecting lead 15 of the electrode A10 and the current collecting lead 25 of the electrode B can be projected in the same direction (in the example of FIG. 10C, + Z direction). In this configuration, the effect of the present invention can be obtained in the Z-axis direction.

  FIG. 10D shows a configuration of a stacked electrode group in the case of using a combination of two types of electrodes A10 having different directions for defining the Z axis. In FIG. 10D, the first and third electrodes A10 from the top are provided with thick portions 40 in the end region in the Z′-axis direction of the coating layer, and the second and fourth electrodes A10 from the top have The thick portion 40 is provided in the end region in the Z ″ axial direction of the coating layer. In FIG. 10D, the Z′-axis direction and the Z ″ -axis direction are orthogonal to each other.

  In FIG. 10E, the thick portion 40 of the electrode A10 is provided in the end region of the coating layer along two types of Z-axis having different directions, that is, the Z′-axis and the Z ″ -axis. In the example shown in FIG. 10E, the Z′-axis direction and the Z ″ -axis direction are orthogonal to each other. Therefore, the thick part 40 is continuously formed in the outer edge area | region of the application layer of electrode A10 along the outer periphery of an application layer. As shown to FIG. 10E, electrode B20 is arrange | positioned so that it may be pinched | interposed by electrode A10 which provided the thick part 40 in the outer edge area | region of the application layer. For this reason, the effects of the present invention can be obtained in the in-plane direction including the Z ′ axis and the Z ″ axis as well as the Z ′ axis direction and the Z ″ axis direction.

  DESCRIPTION OF SYMBOLS 10 ... Electrode A, 11 ... Application layer of electrode A, 15 ... Current collection lead of electrode A, 20 ... Electrode B, 25 ... Current collection lead of electrode B, 30 ... Separator, 40, 40a, 40b, 40c, 40d ... Thick part, 100 ... cylindrical wound electrode group, 110 ... axial core, 120 ... positive electrode plate, 125 ... positive electrode active material coating layer, 126 ... positive electrode current collector, 130 ... negative electrode plate, 135 ... negative electrode Active material coating layer, 136 ... negative electrode current collector, 140 ... separator, 210 ... positive electrode current collector lead, 215 ... positive electrode current collector ring, 216 ... positive electrode collector plate, 220 ... negative electrode current collector lead, 225 ... negative electrode current collector ring 226 ... negative electrode connection plate, 300 ... battery outer can, 310 ... positive electrode terminal cap, 320 ... gasket, 500 ... flat wound electrode group, 510 ... flat shaft core, 610 ... positive current collector plate, 612 ... Positive current collector lead, 6 5... Connection portion between positive current collector lead and positive current collector plate, 620... Positive terminal, 630. Negative current collector plate, 632. Negative current collector lead, 635... Connection portion between negative current collector lead and negative current collector plate. ... negative electrode terminal, 700 ... battery outer can, 710 ... insulating sheet, 750 ... battery top cover, 760 ... pressure release valve, 770 ... injection plug.

Claims (6)

A positive electrode in which a coating layer containing a positive electrode active material is formed on a current collector, a negative electrode in which a coating layer containing a negative electrode active material is formed on a current collector, the positive electrode and the negative electrode In a battery using a coating-type electrode group including a separator that is electrically isolated,
The coating layer of one of the positive electrode and the negative electrode is
The predetermined length in one side direction is longer than the length in the one side direction of the coating layer of the other electrode,
At least a part of the end regions at both ends in the one-side direction is provided with a thick portion whose thickness is thicker than the central portion in the one-side direction,
The other electrode is located between the thick part provided at one end of the one-side direction of the coating layer of the one electrode and the thick part provided at the other end.
A battery using a coating electrode group characterized by the above. A positive electrode in which a coating layer containing a positive electrode active material is formed on a current collector, a negative electrode in which a coating layer containing a negative electrode active material is formed on a current collector, the positive electrode and the negative electrode In a battery using a coating-type electrode group including a separator that is electrically isolated,
The coating-type electrode group is formed by winding the positive electrode and the negative electrode with a predetermined one-side direction as a winding axis through the separator,
The coating layer of one of the positive electrode and the negative electrode is
The length in the one side direction is longer than the length in the one side direction of the coating layer of the other electrode,
At least a part of the end regions at both ends in the one-side direction is provided with a thick portion whose thickness is thicker than the central portion in the one-side direction,
The other electrode is located between the thick part provided at one end of the one-side direction of the coating layer of the one electrode and the thick part provided at the other end.
A battery using a coating electrode group characterized by the above. A positive electrode in which a coating layer containing a positive electrode active material is formed on a current collector, a negative electrode in which a coating layer containing a negative electrode active material is formed on a current collector, the positive electrode and the negative electrode In a battery using a coating-type electrode group including a separator that is electrically isolated,
The coating-type electrode group is formed by laminating a plurality of the positive electrode and the negative electrode via the separator,
The coating layer of one of the positive electrode and the negative electrode is
The predetermined length in one side direction is longer than the length in the one side direction of the coating layer of the other electrode,
At least a part of the end regions at both ends in the one-side direction is provided with a thick portion whose thickness is thicker than the central portion in the one-side direction,
The other electrode is located between the thick part provided at one end of the one-side direction of the coating layer of the one electrode and the thick part provided at the other end.
A battery using a coating electrode group characterized by the above. In the battery using the coating type electrode group according to any one of claims 1 to 3,
From the other electrode, a portion of the current collector where the coating layer is not formed projects as a current collecting lead to one side in the one-side direction,
At one end where the current collecting lead of the other electrode protrudes, a distance S ₁ between the one electrode in a portion where the thick part is not provided, and a distance S ₂ between the one electrode in the thick part A battery using a coating electrode group in which the thickness S ₃ of the other electrode and the current collector thickness S _{4 of the} other electrode satisfy the following formula 1.
S ₁ −S ₂ ≦ S ₃ −S ₄ (Formula 1) In the battery using the coating type electrode group according to any one of claims 1 to 3,
From the one electrode, a portion of the current collector where the coating layer is not formed projects as a current collecting lead to one side in the one side direction,
At one end where the current collecting lead of the one electrode protrudes, a distance T ₁ between the one electrode in a portion where the thick part is not provided, and a distance T ₂ between the one electrode in the thick part A battery using a coated electrode group in which the thickness T ₃ of the other electrode satisfies the following mathematical formula 2.
T ₁ −T ₂ ≦ T ₃ (Formula 2) In the battery using the coating type electrode group according to any one of claims 1 to 3,
The thick part is a battery using a coating-type electrode group provided on one side or both sides of the one electrode.

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