JP2006004729A - Electrochemical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical element having winding structure enhancing joining strength between a current collectors constituting electrode plates of a positive electrode and a negative electrode and a current collecting plate, and enhancing current capacity. <P>SOLUTION: The current collectors are projected from upper and lower ends of an electrode group 4 formed by winding a positive plate 1 having a belt-shaped current collector coated with an active material and a negative plate 2 having a belt-shaped current collector coated with an active material through a belt-shaped separator 3, portions other than a wound outermost circumferential portion are pressed to form a flat portion, the current collectors are welded to the flat portion, and the outermost circumferential portion is welded to the current collectors. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrochemical element such as a battery or an electric double layer capacitor, in which positive and negative electrode plates are wound and accommodated in a container.

  Electrochemical elements such as batteries and electric double layer capacitors use a group of electrode plates having a wound structure in which a positive electrode plate and a negative electrode plate are wound via a separator in order to increase the reaction area per unit volume. Is widely used. The electrode plate group is housed in a metal container together with the electrolyte and sealed, and the positive electrode plate and the negative electrode plate are respectively connected to the portions serving as the positive electrode external connection terminal and the negative electrode external connection terminal to form an electrochemical element that can be externally connected. The

  Since the positive electrode plate and the negative electrode plate are formed by applying an active material to a current collector formed of a foil or a net-like thin metal plate, each positive and negative current collector is connected to a positive external connection terminal and a negative external connection. A current path is formed by lead connection to a portion to be a terminal. At that time, if the current collector is connected from one location to the external connection terminal, the wound belt-like current collector has a longer current path from the location away from the connection location, so a relatively large current There was a problem that loss and temperature increase occurred when charging / discharging. In particular, in order to make effective use of the characteristics capable of charging and discharging energy in a short time, such as an electric double layer capacitor, the necessity of reducing the internal resistance of the current path becomes greater.

  In addition, the usage of secondary batteries and electric double layer capacitors to power supplies for mobile devices and mobile objects is increasing, and when applied to devices subject to such vibrations and impacts, they are housed in metal containers. When vibration or impact is applied to the electrode plate group, there is a risk of breakage or peeling at the joint portion of the current collector formed of a thin metal foil, and a connection structure that can withstand vibration and impact is required.

  In order to solve the problems related to the connection between the electrode plate group and the external connection terminal portions of the positive electrode and the negative electrode as described above, the positive electrode plate and the negative electrode plate are wound into a cylindrical shape via a separator to form the electrode plate group. A part of the current collector constituting the positive electrode plate or the negative electrode plate is formed so as to protrude from one end of the electrode plate group, and a plane pressing force is applied to the current collector protruding from the end from the cylindrical axis direction. The current collector is bent inward to form a flat part, and a current collector plate is welded to the flat part to improve the current collection efficiency and to improve the welding strength against vibration etc. The structure is known (see Patent Document 1).

  It is also possible to wind the current collector that protrudes from the end after being wound into a cylindrical shape with the same configuration, shape it so that adjacent current collectors overlap each other, and weld the current collector plate to this Thus, a configuration of a cylindrical storage battery in which the current distribution is made uniform to improve the high rate discharge characteristic is known (see Patent Document 2).

The above two examples are both batteries, but in an electric double layer capacitor in which a positive and negative electrode plate is wound in a cylindrical shape, a plurality of positive and negative electrode plates are arranged on the same line in the radial direction from the current collector of the wound positive and negative plates. It is known that the electrode plate group is formed so that the current collecting tabs protrude, and a plurality of current collecting tabs in the radial direction are bundled and welded in a state of being sandwiched by terminal members of the same material to form a lead terminal portion. (See Patent Document 3).
JP 2000-294222 A (pages 2 to 4, FIG. 1) JP 2000-323117 A (pages 2 and 3, FIG. 1) Japanese Patent Laid-Open No. 10-050556 (pages 3 to 4, FIG. 6)

  However, in the configuration shown in Patent Document 1 in which the current collector protruding from the end portion is bent to form a flat surface and welded to the current collector plate placed thereon, the cylindrical electrode plate group Since laser welding is linearly performed along the welding line set in the radial direction, there is a problem that the welding area is small, sufficient welding strength cannot be obtained, and internal resistance cannot be sufficiently reduced.

  In particular, when the electrochemical element requires high output such as HEV or electric tool and is applied to an application to which vibration or impact is applied, it is difficult to ensure sufficient vibration resistance or impact resistance. Further, when a large charge / discharge current flows in a small welding area, power loss and heat generation are likely to occur, and the performance cannot be fully exhibited. Note that Patent Document 2 does not disclose a welding method between the end of the folded current collector and the current collector plate, and the connection is made only by contact caused by overlapping the folded current collectors. Thus, it is not possible to obtain sufficient current capacity and sufficient connection strength.

  Moreover, in the structure shown in the said patent document 3 which forms several current collection tabs in the radial direction of the positive electrode plate and negative electrode plate which were wound by the cylindrical shape, several current collection tabs protrude in the electrode plate cut out in strip shape As a result, the material for forming the electrode plate is poor and there is a problem of lack of productivity.

  The present invention was devised in view of the above problems of the prior art, and the object of the present invention is to connect the current collector and the current collector plate with high welding strength and a large current capacity. It is an object of the present invention to provide an electrochemical device having the connection structure described above.

  In order to achieve the above object, a first invention of the present application is a strip separator comprising a positive electrode plate coated with an active material on a strip-shaped positive electrode current collector and a negative electrode plate coated with an active material on a strip-shaped negative electrode current collector. The electrode plate group wound in a cylindrical shape via the electrode is housed in a metal container together with the electrolyte, and the positive electrode current collector serves as a positive electrode external connection terminal, and the negative electrode current collector serves as a negative electrode external connection terminal And a positive electrode current collector and / or a negative electrode current collector provided with a current collector exposed portion to which an active material is not applied on one end side in the width direction. The electrode plate group is formed in a state in which the current collector exposed portion of the positive electrode plate and / or the negative electrode plate protrudes at both ends, and other than the current collector exposed portion which becomes the outermost periphery and / or innermost periphery. A current collector plate is welded on a flat surface of the current collector exposed portion formed by bending the current collector exposed portion of In which the outermost and / or innermost collector-exposed portion is characterized by comprising welded to the outer periphery and / or the inner periphery on the collector plate.

  According to the above configuration, the current collector exposed portion in a state of protruding from the electrode plate group is bent at a portion excluding the outermost and / or innermost portion to form a current collector exposed portion flat surface. Since it is welded to one side of the plate, the welding area is large, and the welding strength and current collecting current capacity can be sufficiently secured. Furthermore, since the remaining outermost part and / or innermost part is welded to the other surface of the current collector plate, the current collector plate is joined in a state of being surrounded by the exposed portion of the current collector, so High connection structure is obtained. This connection structure can be further increased in welding strength by constituting both the positive electrode plate and the negative electrode plate. Further, the current collector plate is formed in a donut shape, and the outermost and innermost current collectors are formed. By welding both of the exposed portions to the current collector plate, the welding strength can be further increased.

  In addition, the second invention of the present application provides a cylindrical plate-shaped positive electrode plate coated with an active material on a strip-shaped positive electrode current collector and a negative electrode plate coated with an active material on a strip-shaped negative electrode current collector through a strip-shaped separator. The electrode plate group wound around is accommodated in a metal container together with the electrolyte, and the positive electrode current collector is bonded to a portion serving as a positive electrode external connection terminal, and the negative electrode current collector is bonded to a portion serving as a negative electrode external connection terminal. The positive electrode current collector and / or the negative electrode current collector is provided with a current collector exposed portion to which no active material is applied on one end side in the width direction of the positive electrode current collector and / or the negative electrode current collector. The electrode plate group is formed in a state in which the current collector exposed portion of the positive electrode plate and / or the negative electrode plate protrudes, and the other current collector exposure is performed while leaving the current collector exposed portion serving as the outermost circumference and / or innermost circumference. The current collector plate is welded and joined to the flat surface of the current collector exposed portion formed by bending the portion at least once, and the outside of the current collector plate Collector-exposed portion of the outermost and / or innermost periphery side and / or inner periphery on is characterized in that formed by welding.

  According to the above configuration, the current collector exposed portion excluding the outermost and / or innermost portion when wound around the electrode plate group is bent one or more times so as to increase the thickness. Therefore, when the electrode plate on which the current collector exposed portion is formed is wound, the current collector exposed portion is easily deformed in a zigzag shape on the winding arc line, and the thickness of the current collector exposed portion is increased. At the same time, the current collector plate can be received by zigzag deformation to increase the weld area and the joint strength, thereby ensuring sufficient welding strength and current collection current capacity. Furthermore, since the remaining outermost part and / or innermost part is welded to the other surface of the current collector plate, the current collector plate is joined in a state of being surrounded by the exposed portion of the current collector, so High connection structure is obtained. This connection structure can be further increased in welding strength by constituting both the positive electrode plate and the negative electrode plate. Further, the current collector plate is formed in a donut shape, and the outermost and innermost current collectors are formed. By welding both of the exposed portions to the current collector plate, the welding strength can be further increased.

  In each of the above configurations, it is desirable to form a notch between the current collector exposed portion which is the outermost periphery and / or innermost periphery and the current collector exposed portion formed on the flat surface of the current collector exposed portion. It is possible to prevent the current collector exposed portion at the outermost periphery and / or the innermost periphery from being pulled and deformed by pressurization when bending the flat surface of the current exposed portion or welding the current collector plate.

  In addition, it is desirable to form a plurality of cuts in the current collector exposed portion that is the outermost periphery and / or innermost periphery, and it is easy to bend the current collector exposed portion along the circular shape of the current collector plate. Become.

  In addition, the exposed portion of the current collector is formed by applying an insulation coating to a portion from the active material coating end in the width direction to the position substantially the same as the width of the separator to a thickness substantially equal to the active material coating thickness. In addition, it is possible to eliminate the possibility that a thin current collector buckles when a flat surface forming press or pressure is applied during welding, or when a vibration or impact is applied, resulting in poor welding or an internal short circuit.

  According to the present invention, the current collector and the current collector plate can be welded together on the surface, and the current collector plate is joined so as to be wrapped with the current collector. A large capacity can be secured. Therefore, it is possible to construct an electrochemical device that can handle vibrations and impacts easily, such as a portable device or a moving body, and can handle even a relatively large charge / discharge current.

  The present embodiment shows an example in which the connection structure according to the present invention is applied to a lithium ion secondary battery which is an example of an electrochemical element. The lithium ion secondary battery described here is formed in a cylindrical shape having a diameter of 18.3 mm and a height of 64.7 mm.

  As shown in FIG. 1, the lithium ion secondary battery includes a positive electrode plate 1 in which a positive electrode active material 1b is applied on both surfaces of a positive electrode current collector 1a, and a negative electrode active material 2b on both surfaces of the negative electrode current collector 2a. The electrode plate group 4 formed by overlapping the attached negative electrode plate 2 with a separator 3 and winding it in a cylindrical shape is housed together with an electrolyte in a battery can 6 formed in a bottomed cylindrical shape, and the negative electrode The negative electrode current collector 2a of the plate 2 is connected to the battery can 6 serving as the negative electrode external connection terminal, and the positive electrode plate 1 is connected to the sealing plate 7 serving as the positive electrode external connection terminal by insulating the battery can 6 and sealing the opening. The positive electrode current collector 1a is connected.

More specifically, the positive electrode active material 1b is prepared by mixing electrolytic manganese dioxide (MnO ₂ ) and lithium carbonate (Li ₂ CO ₃ ) so that Li / Mn = 1/2 and firing at 800 ° C. for 20 hours. LiMn ₂ O ₄ , conductive agent acetylene black, and binder polyvinylidene fluoride were mixed in a weight ratio of 92: 3: 5, respectively, and kneaded into a paste. A solution dissolved in n-methylpyrrolidone (NMP) which is a vinylidene solvent is used. This positive electrode active material 1b paste was applied to both sides of a positive electrode current collector 1a using an aluminum foil having a thickness of 15 μm, leaving a current collector exposed portion of a predetermined width at one side edge, and then dried. The layer of the positive electrode active material 1b is formed so that the total film thickness on both sides after drying is 280 μm. The positive electrode active material 1b is compression-molded so that the positive electrode plate 1 has a width of 55 mm, a length of 570 mm, and a thickness of 200 μm.

  In the negative electrode active material 2b, artificial graphite and a binder styrene butadiene rubber (SBR) are mixed at a weight ratio of 97: 3, and the negative electrode active material 2b is kneaded into a paste, so that the styrene butadiene rubber is water-soluble. Dispersion liquid is used. The mixing ratio is a ratio as a solid content. This negative electrode active material 2b paste was applied to both sides of a negative electrode current collector 2a using a copper foil having a thickness of 14 μm with a predetermined width of the current collector exposed part left on one side edge and dried. The negative electrode plate 2 is compression-molded so that the electrode plate has a width of 61 mm, a length of 600 mm, and a thickness of 170 μm.

  The positive electrode plate 1 and the negative electrode plate 2 configured as described above are overlapped with a separator 3 using a microporous polyethylene film having a width dimension larger than the width of the negative electrode active material 2b, and wound into a spiral shape to form a cylinder. A shaped electrode group 4 is formed.

In addition, the electrolytic solution was 1 mol / dm ^{3 of} lithium hexafluorophosphate (LiPF ₆ ) as a solute in a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a mixing ratio of 1: 1 by volume. The one dissolved in the concentration is used.

  Example 1 A connection structure in which the positive electrode current collector 1a of the positive electrode plate 1 of the electrode plate group 4 having the above-described configuration is connected to the sealing plate 7 and the negative electrode current collector 2a of the negative electrode plate 2 is connected to the battery can 6 is described below in Example 1. The second embodiment will be described.

  As shown in FIG. 2 (a), the positive electrode plate 1 has a positive electrode current collector exposed portion 9 in which the positive electrode active material 1b is not applied to one side edge in the width direction of the positive electrode current collector 1a formed in a strip shape. Form in width. When the positive electrode current collector exposed portion 9 is formed in the electrode plate group 4 by winding the positive electrode plate 1 and the negative electrode plate 2 in a cylindrical shape via the separator 3, the outermost peripheral portion 9b, The other part is defined as a flat surface forming part 9a. It is desirable to form a cut line 9c at the boundary between the outermost peripheral part 9b and the flat surface forming part 9a, and when the flat surface forming part 9a is bent after being formed in the electrode plate group 4, the outermost peripheral part is formed. 9b can be prevented from being pulled. Moreover, it is desirable to form the cutting line 9d in the width direction of the positive electrode plate 1 at a required interval in the outermost peripheral part 9b, and a process of bending the outermost peripheral part 9b on the outer periphery of the disc-shaped positive current collector plate 10 is performed. Can be easily.

  As shown in FIG. 2 (b), the negative electrode plate 2 is a negative electrode in which the negative electrode active material 2b is not applied to the other side edge of the negative electrode current collector 2a formed in a strip shape on the opposite side to the positive electrode plate 1 in the width direction. The current collector exposed portion 12 is formed to have a width of 5 mm. In the case of the negative electrode current collector exposed portion 12, similarly to the positive electrode plate 1, the outermost part when formed in the electrode plate group 4 is the outermost part 12 b and the other part is the flat surface forming part 12 a. It is desirable to form a cut line 12c at the boundary between the outermost peripheral portion 12b and the flat surface forming portion 12a, and when the flat surface forming portion 12a is bent after being formed in the electrode plate group 4, the outermost peripheral portion is formed. It can prevent that 12b is pulled. Moreover, it is desirable to form the cutting line 12d in the width direction of the positive electrode plate 1 at a required interval in the outermost peripheral part 12b, and a process of bending the outermost peripheral part 12b on the outer periphery of the disc-shaped negative electrode current collector plate 11 is performed. Can be easily.

  The separator 3 is formed in a band shape having a width larger than the width of the positive electrode active material 1b and the negative electrode active material 2b, and the positive electrode plate 1 and the negative electrode plate 2 are overlapped and wound with the separator 3 interposed therebetween. The positive electrode current collector exposed portion 9 of the positive electrode plate 1 protrudes 2 mm from one end of the electrode plate group 4, and the negative electrode current collector exposed portion 12 of the negative electrode plate 2 protrudes 2 mm from the other end.

  Next, the outermost peripheral portion 9b of the positive electrode current collector exposed portion 9 protruding from one end of the electrode plate group 4 is left, and the flat surface is formed by the flat surface forming portion 9a that is bent by pressing the flat surface forming portion 9a by 1.5 mm. In this state, the flat surface forming portion 9a and the positive electrode current collector plate 10 are welded in a state where the positive electrode current collector plate 10 is disposed in contact with the flat surface. Further, the outermost peripheral portion 9b left without being pressed is bent on the outer periphery of the positive electrode current collector plate 10 and welded in a state where both are pressed. The welding method at this time is preferably resistance welding.

  Similarly, on the negative electrode side, the outermost peripheral portion 12b of the negative electrode current collector exposed portion 12 protruding from the other end of the electrode plate group 4 is left, and the flat surface forming portion 12a is pressed and bent by 1.5 mm. A flat surface is formed by the surface forming portion 12a, and the negative electrode current collector plate 11 is disposed in contact with the flat surface, and the flat surface forming portion 12a and the negative electrode current collector plate 11 are welded in a state where both are pressed. Further, the outermost peripheral portion 12b left without being pressed is bent on the outer periphery of the negative electrode current collector plate 11, and welded in a state where both are pressed. Resistance welding is also preferable for the negative electrode side welding method.

  The electrode plate group 4 in which the positive electrode current collector plate 10 and the negative electrode current collector plate 11 are joined to both ends is accommodated in the battery can 6, and the bottoms of the negative electrode current collector plate 11 and the battery can 6 are resistance welded. After the positive electrode connection piece 10a joined to the electric plate 10 is pressed against the battery lid 7 and laser-welded, an electrolyte is injected into the battery can 6 and the electrode plate group 4 is vacuum impregnated. The opening is sealed with a battery lid 7 via a gasket 8 to form a lithium ion secondary battery.

  With the above configuration, the positive electrode current collector exposed portion 9 of the positive electrode current collector 1a is not only welded to the current collector plate 10 at the flat surface forming portion 9a, but the outermost peripheral portion 9b that is not formed on the flat surface is also positive electrode current collector. Since it is welded to the plate 10 and joined so as to enclose the positive electrode current collector plate 10, the current capacity between the positive electrode current collector 1a and the positive electrode current collector plate 10 is large, and the welding strength can be increased. Since the negative electrode current collector 2a is configured in the same manner, the lithium ion secondary battery is less likely to be broken or peeled off at the joint even when applied in an environment subject to vibrations or shocks such as portable devices or moving objects. Is configured. Moreover, even if it is applied to a device in which a relatively large charge / discharge current flows, such as an electric tool or a hybrid vehicle, a sufficient current capacity can be obtained, and heat generation and deterioration can be suppressed.

  Further, in the above configuration, the positive electrode plate 1 and the negative electrode plate 2 are wound only on the positive electrode current collector 1a and the negative electrode current collector 2a which are the outermost periphery when they are wound to form the electrode plate group 4. As shown in FIG. 3, the positive and negative current collector plates 10 and 11 are formed in a donut shape, and the positive and negative flat surface forming portions 9a and 9a are joined to the current collector plates 10 and 11, respectively. 12a is welded to the positive and negative current collectors 10 and 11, respectively, and in addition to the outermost peripheral portions 9b and 12b of the positive and negative electrodes, the innermost peripheral portions 9e and 12e of the positive and negative electrodes are also made of the positive and negative electrodes. If it comprises so that it may weld to each current collecting plate 10 and 11, a stronger joining structure will be obtained.

  As shown in FIG. 4 (a), the positive electrode plate 1 has a positive electrode current collector exposed portion 9 in which the positive electrode active material 1b is not applied to one side edge in the width direction of the positive electrode current collector 1a formed in a strip shape. Form in width. When the positive electrode current collector exposed portion 9 is formed in the electrode plate group 4 by winding the positive electrode plate 1 and the negative electrode plate 2 in a cylindrical shape via the separator 3, the outermost peripheral portion 9b, The other part is defined as a flat surface forming part 9a. A cut line 9c is formed at the boundary between the outermost peripheral part 9b and the flat surface forming part 9a to separate the two parts. As shown in the figure, the flat surface forming portion 9a is folded once or more so that the thickness of the positive electrode current collector exposed portion 9 is increased. Moreover, it is desirable to form the cutting line 9d in the width direction of the positive electrode plate 1 at a required interval in the outermost peripheral part 9b, and a process of bending the outermost peripheral part 9b on the outer periphery of the disc-shaped positive current collector plate 10 is performed. Can be easily.

  As shown in FIG. 4B, the negative electrode plate 2 is a negative electrode in which the negative electrode active material 2b is not applied to the other side edge of the negative electrode current collector 2a formed in a strip shape on the opposite side to the positive electrode plate 1 in the width direction. The current collector exposed portion 12 is formed to have a width of 5 mm. In the case of the negative electrode current collector exposed portion 12, similarly to the positive electrode plate 1, the outermost part when formed in the electrode plate group 4 is the outermost part 12 b and the other part is the flat surface forming part 12 a. A cut line 12c is formed at the boundary between the outermost peripheral part 12b and the flat surface forming part 12a to separate the two parts. As shown in the drawing, the flat surface forming portion 12a is folded once or more to make the thickness of the positive electrode current collector exposed portion 12 increased. Moreover, it is desirable to form the cutting line 12d in the width direction of the positive electrode plate 1 at a required interval in the outermost peripheral part 12b, and a process of bending the outermost peripheral part 12b on the outer periphery of the disc-shaped negative electrode current collector plate 11 is performed. Can be easily.

  A positive electrode current collector exposed portion 9 and a negative electrode current collector are disposed at both ends of an electrode plate group 4 formed by winding the positive electrode plate 1 and the negative electrode plate 2 formed as described above in a cylindrical shape with a separator 3 interposed therebetween. A state in which the body exposed portion 12 protrudes is obtained. When the positive electrode plate 1 and the negative electrode plate 2 are wound in a cylindrical shape via the separator 3, the portions other than the flat surface forming portions 9a and 12a of the positive electrode plate 1 and the negative electrode plate 2 are positioned on the winding arc. However, since the flat surface forming portions 9a and 12a which are formed to be folded and increase in thickness are not smoothly wound, the flat surfaces adjacent to each other in the diametrical direction are likely to be zigzag on the winding arc line. The formation portions 9a and 12a are in contact with each other, and a flat surface is formed as a whole.

  As shown in FIG. 5, the outermost peripheral portion 9b of the positive electrode current collector exposed portion 9 protruding from one end of the electrode plate group 4 is left, and the positive electrode current collector plate 10 is disposed in contact with the flat surface forming portion 9a. The flat surface forming portion 9a and the positive electrode current collector plate 10 are welded in a state in which is pressed. It is preferable to use resistance welding at a plurality of locations for welding. By joining at a plurality of locations, current capacity can be ensured and joint strength can be improved. Further, the outermost peripheral portion 9b left without being pressed is bent on the outer periphery of the positive electrode current collector plate 10 and welded in a state where both are pressed.

  Similarly, on the negative electrode side, the outermost peripheral portion 12b of the negative electrode current collector exposed portion 12 protruding from the other end of the electrode plate group 4 is left, and the negative electrode current collector plate 11 is disposed in contact with the flat surface forming portion 12a. Then, the flat surface forming portion 12a and the negative electrode current collector plate 11 are resistance welded in a state in which both are pressed. Further, the outermost peripheral portion 12b left without being pressed is bent on the outer periphery of the negative electrode current collector plate 11, and welded in a state where both are pressed.

  The electrode plate group 4 in which the positive electrode current collector plate 10 and the negative electrode current collector plate 11 are joined to both ends is accommodated in the battery can 6, and the bottoms of the negative electrode current collector plate 11 and the battery can 6 are resistance welded. After the positive electrode connection piece 10a joined to the electric plate 10 is pressed against the battery lid 7 and laser-welded, an electrolyte is injected into the battery can 6 and the electrode plate group 4 is vacuum impregnated. The opening is sealed with a battery lid 7 via a gasket 8 to form a lithium ion secondary battery.

  In order to verify the bonding strength of the lithium ion secondary battery according to the embodiment described above, on both the positive electrode side and the negative electrode side, the entire surface of the current collector protrusion is pressed to form a flat portion by the protrusion tip itself, A drop test was conducted using a lithium ion secondary battery with a current collector plate welded to the flat part and the other structure formed in the same structure as the embodiment structure as a comparative example.

  In the drop test, for each of the 100 batteries in the example and the comparative example, one cycle was performed by dropping each of the batteries from the height of 75 cm in the upright, inverted, and side directions.

  The internal resistance value of the battery was measured every cycle, and it was determined whether the current collector plate was peeled off from the current collector at the positive electrode current collector or the negative electrode current collector due to a drop impact, and it was not possible to ensure conduction. When the internal resistance value of the battery increased, it was considered that the current collector plate was peeled from the current collector, and the number of the battery was counted. The results are shown in Table 1.

実施例の電池は９０サイクルで初めて電池の内部抵抗値が上昇したのに対し、比較例の電池では３０サイクルで電池の内部抵抗値の上昇が観察された。これは、正極集電部もしくは負極集電部における集電板と集電体との剥離を抑制すること関して、実施例の構造の電池の方が比較例よりも優れているためと考えられる。

In the battery of the example, the internal resistance value of the battery increased for the first time in 90 cycles, whereas in the battery of the comparative example, an increase in the internal resistance value of the battery was observed in 30 cycles. This is considered to be because the battery of the structure of the example is superior to the comparative example in terms of suppressing the separation between the current collector plate and the current collector in the positive electrode current collector or the negative electrode current collector. .

  In the configurations of Example 1 and Example 2 described above, the positive and negative current collector exposed portions 9 and 12 are located at substantially the same position as the width of the separator 3 from the coating ends of the positive and negative active materials 1b and 2b in the width direction. It is desirable to apply an insulating coating to the part up to the thickness of the active material coating, so that the bases of the positive and negative current collector exposed portions 9 and 12 are reinforced, and at the same time, the insulation is reinforced. Therefore, it is possible to eliminate the possibility that the thin current collector buckles when a flat surface forming press or pressure is applied during welding, or when a vibration or impact is applied, resulting in poor welding or internal short circuit.

  Moreover, although embodiment described above demonstrated the lithium ion secondary battery, the same effect is acquired in the electrochemical element which comprised electrode plates in winding structure, such as another battery and an electric double layer capacitor.

  In the present invention, a positive electrode plate and a negative electrode plate are wound through a separator, and current collectors of the positive electrode plate and the negative electrode plate are joined to the positive electrode and negative electrode current collector plates, respectively. It is possible to improve the bonding strength and current capacity of an electrochemical element in which the plate has a wound structure.

1 is a schematic diagram showing a longitudinal structure of a lithium ion secondary battery of Example 1. FIG. Sectional drawing and top view which show the structure of the positive electrode plate (a) and negative electrode plate (b) in a structure same as the above. FIG. 3 is a schematic view showing a longitudinal structure modification of the lithium ion secondary battery of Example 1. Sectional drawing and top view which show the structure of the positive electrode plate (a) in Example 2, and a negative electrode plate (b). The schematic diagram which shows the longitudinal cross-section of a lithium ion secondary battery using an electrode plate same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 1a Positive electrode current collector 1b Positive electrode active material 2 Negative electrode plate 2a Negative electrode current collector 2b Negative electrode active material 3 Separator 4 electrode plate group 6 Battery can 9a, 12a Flat surface formation site 9b, 12b Outermost peripheral site 9c, 12c Notch Line 9d, 12d Cutting line 9e, 12e Innermost peripheral part 10 Positive electrode current collector 11 Negative electrode current collector

Claims (5)

An electrode plate group obtained by winding a positive electrode plate coated with an active material on a strip-shaped positive electrode current collector and a negative electrode plate coated with an active material on a strip-shaped negative electrode current collector through a strip-shaped separator is a metal together with an electrolyte. An electrochemical element housed in a container and connected to a portion where the positive electrode current collector serves as a positive electrode external connection terminal, and a portion where the negative electrode current collector serves as a negative electrode external connection terminal,
The positive electrode current collector and / or the negative electrode current collector is provided with a current collector exposed portion to which no active material is applied on one end side in the width direction, and the positive electrode plate and / or the negative electrode plate are provided at one or both ends. A current collector formed by forming the electrode plate group in a state where the current collector exposed portion protrudes and bending the other current collector exposed portion while leaving the current collector exposed portion serving as the outermost and / or innermost periphery. A current collector plate is welded on a flat surface of the body exposed portion, and an outermost and / or innermost current collector exposed portion is welded on the outer periphery and / or inner periphery of the current collector plate. An electrochemical element. An electrode plate group in which a positive electrode plate coated with an active material on a strip-shaped positive electrode current collector and a negative electrode plate coated with an active material on a strip-shaped negative electrode current collector are wound in a cylindrical shape via a strip-shaped separator Is an electrochemical element that is housed in a metal container together with an electrolyte, and is connected to a portion where the positive electrode current collector serves as a positive electrode external connection terminal and a portion where the negative electrode current collector serves as a negative electrode external connection terminal. ,
The positive electrode current collector and / or the negative electrode current collector is provided with a current collector exposed portion to which no active material is applied on one end side in the width direction, and the positive electrode plate and / or the negative electrode plate are provided at one or both ends. The electrode plate group is formed in a state where the current collector exposed portion protrudes, and is formed by bending the other current collector exposed portion one or more times while leaving the current collector exposed portion serving as the outermost periphery and / or innermost periphery. A current collector plate is welded on the flat surface of the current collector exposed portion, and the outermost and / or innermost current collector exposed portion is welded on the outer periphery and / or inner periphery of the current collector plate. The electrochemical element characterized by the above-mentioned. The notch | incision is formed between the collector exposed part used as the outermost periphery and / or innermost periphery, and the collector exposed part formed in a collector exposed part flat surface. Electrochemical element. The electrochemical device according to any one of claims 1 to 3, wherein a plurality of cuts are formed in a current collector exposed portion which is an outermost periphery and / or an innermost periphery. The current collector exposed portion is formed by applying an insulating coating to a portion from the active material coating end in the width direction to a position substantially the same as the width of the separator to a thickness substantially equal to the active material coating thickness. The electrochemical element as described in any one of 1-4.

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