JP2008166030A - Manufacturing method of spiral electrode body, and manufacturing method of closed battery using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a battery with excellent high-rate discharge characteristics. <P>SOLUTION: The manufacturing method of the spiral electrode body made up by winding around a first electrode with an active material applied on a strip electrode core body and a second electrode with a polarity different from that of the first electrode and with an active material applied on a strip electrode core body through a separator, comprises a take-up body making step, in which a core body exposed part is formed without any active material applied at least on one edge of the first electrode in a width direction, and the first electrode, the separator and the second electrode are folded together with the core body exposed part of the first electrode in a state protruded toward front in a width direction in excess of the separator width, and the three entities are wound around in a length direction to make a take-up body with the core body exposed part of the first electrode protruded in one direction, and a tapping step for flattening the protruded part in the above direction by putting the take-up body under an up-and-down movement in an axis direction, tapping the protruded part in the above one direction, and bending the protruded core body exposed part toward a main body side of the take-up body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a spiral electrode body and a method of manufacturing a sealed battery using the same, and more particularly to an electrical connection method of the spiral electrode body.

  Today, mobile information terminals such as mobile phones and laptop computers are rapidly becoming more functional, smaller, and lighter. As a driving power source for these terminals, non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries having high energy density and high capacity are widely used.

  In particular, a battery using a spiral electrode body obtained by winding a positive and negative electrode coated with a positive and negative active material on a strip-shaped electrode core (current collector) through a separator is widely used in applications that require high-rate discharge. in use. Some alkaline storage batteries, such as nickel cadmium batteries, have a current collector plate welded to an end surface in the winding axis direction of an electrode winding body in order to perform high-rate discharge. However, since the electrode core of a lithium ion battery is made of a soft and very thin material of several tens of μm or less (for example, copper foil, aluminum foil), the electrode core and the current collector plate are directly welded. Difficult to do. A method of clamping and welding the side surface of the spiral electrode body is also conceivable, but the winding pressure cannot be increased sufficiently, resulting in winding displacement. Difficult to do.

  For this reason, in the conventional battery, a current collecting tab is attached to a part of the electrode core, and the tab and the current collecting plate are fixed by welding, but this type of battery is used for a wheelchair or a power tool. The use in applications that require high output at the time of startup, such as drive power supplies, is expanding, and in these applications, batteries that are particularly excellent in high-rate discharge characteristics are required. However, the conventional tab current collecting system has a problem that it is difficult to extract a large current in a short time.

  Here, the following patent documents 1-10 are mentioned as a technique regarding the current collection method of a battery.

JP 2000-294222 A JP 2000-323117 A Japanese Unexamined Patent Publication No. 2000-40502 JP 2002-170547 A JP 2002-75319 A JP 2004-139777 A JP 2004-95487 A JP 2006-12801 A JP 2006-32112 A JP 2006-4729 A

  In Patent Document 1, the current collectors of the electrode plates are protruded from both ends of the electrode plate group, the protrusions are pressed to form a flat portion by the current collector itself, and the current collector plate is joined to the flat portion. According to this technology, the current collection efficiency can be increased, and the temperature rise during charging and discharging can be reduced.

  Patent Document 2 is a technique for bending at least one core exposed part of the core exposed part of the positive electrode plate edge or the core exposed part of the negative electrode plate edge of the spiral electrode group. According to this technique, It is said that the high rate discharge characteristics can be improved.

  In Patent Document 3, a first electrode and a second electrode are respectively projected outward from both side end portions of a laminated electrode wound in a jelly roll shape, and a pair of slits parallel to each other are formed on the side end surfaces. This is a technique for forming an electrode surface at a position inward of the side end face of the laminated electrode by bending the electrode of the portion partitioned by the slit, and connecting a current collecting tab to this electrode face. It is said that the current collecting ability can be improved.

  Patent Document 4 is a technique of forming a bent portion provided at one of the surface direction end of the negative electrode and the surface direction end of the positive electrode, and bringing the bent portion into surface contact with the current collector plate. According to the technology, the negative electrode current collector plate and the positive electrode current collector plate can be more reliably and easily connected to the negative electrode and the positive electrode.

  Patent Document 5 is a technique of providing a bent portion at one of the edge in the surface direction of the negative electrode and the edge in the surface direction of the positive electrode. According to this technique, it is difficult to cause a short circuit between the negative electrode and the positive electrode. .

  In Patent Document 6, at least one of an upper surface and a lower surface of an electrode body is made to protrude a core material exposed portion of either a positive electrode plate or a negative electrode plate, and a flat portion is formed by the tip of the protruding portion itself. It is a technology for joining current collector plates, and according to this technology, it is said that stable current collecting characteristics can be obtained even in rough use.

  Patent Document 7 discloses that the positive electrode side band-shaped current collector and / or the negative electrode side band-shaped current collector protruding in the winding width direction of the electrode plate group are formed by notches or notches formed in a radial arrangement from the winding axis. It is divided into a plurality of connection pieces, and each connection piece is bent at right angles toward the winding axis, and this connection piece is joined to the current collector. According to this technology, excellent drop resistance characteristics Is obtained.

  In Patent Document 8, the negative electrode side of the separator is bent in the center direction of the electrode group, and the negative electrode plate having a flexible base has an electrode end portion in which almost no active material exists on a part of the negative electrode side end surface, At least a part of the electrode end is exposed from the folded separator, and the exposed part of the electrode end is electrically connected to the battery terminal or the battery case through the negative current collector plate or directly. According to this technique, it is said that it is possible to prevent a short circuit due to the active material falling off the electrode plate.

  Patent Document 9 discloses that a current collector (electrode core, hereinafter the same) of a positive electrode plate and / or a negative electrode plate forms a current collector exposed portion to which an active material is not applied on one end side in the width direction. The current-exposed portion is a current-exposed portion that protrudes from the end when it is formed on the electrode plate group by insulatingly covering a portion from the active material coating end in the width direction to the position substantially the same as the width of the separator. Is a technology that welds the current collector plate to the welded surface that is bent by pressing, and according to this technology, the electrical connection between the current collector and the current collector plate is stable, and the current collector and the current collector are It is said that sufficient welding strength with the plate can be secured.

  In Patent Document 10, a strip-shaped separator is disposed between a positive electrode plate in which an active material is applied to a strip-shaped current collector and a negative electrode plate in which an active material is applied to a strip-shaped current collector. The current collector is constructed so that the current collector protrudes from the upper and lower end faces of the electrode plate group, and other parts except the outermost wound part are pressed to create a flat part, and the current collector is welded to the flat part. Later, it is a technique of welding the outermost peripheral part to the current collector, and according to this technique, the joint strength and current capacity between the current collector and the current collector plate can be improved.

  With these technologies, it is necessary to bend the current collector. However, if you try to fold the current collector by applying force to a thin and soft current collector, the flat part cannot be produced due to deformation or breakage of the current collector. There is a risk that the current collector plate cannot be welded in good condition.

  This invention is made in view of the above, Comprising: It aims at providing the manufacturing method of the spiral electrode body which can manufacture the battery excellent in the high-rate discharge characteristic, and the manufacturing method of a battery using the same. .

  The present invention according to the method of manufacturing a spiral electrode body for solving the above-described problems is a first electrode in which an active material is applied to a strip-shaped electrode core and an electrode having a different polarity from the first electrode. In the method of manufacturing a spiral electrode body in which a second electrode having an active material coated on a strip-shaped electrode core is wound through a separator to form a spiral electrode body, at least in the width direction of the first electrode A core exposed portion not coated with an active material is formed on one edge, and the first electrode, the separator, and the second electrode are connected to each other, and the core exposed portion of the first electrode extends beyond the separator width. A winding body producing step of producing a winding body in which the core body exposed portion of the first electrode is projected on one surface by overlapping the three members in a longitudinal direction and winding the three members in the longitudinal direction; The winding body is moved up and down in the axial direction, and the one surface is tapped. And by, by bending the substrate exposed portion protruding body of the winding body, characterized in that it comprises a tapping step of flattening said one side.

  In this configuration, there is a tapping step using a tapping method, but according to the tapping method, a force of equal and moderate strength (self-weight of the electrode body) is applied to the entire surface of one surface of the winding body (the entire surface orthogonal to the axial direction). Therefore, the core exposed portion of the first electrode protruded from the one surface is bent in a direction substantially perpendicular to the axial direction of the spiral electrode body without breaking, and the wound body A shape extending in the axial direction is formed. On this flat surface, the area occupied by the core of the first electrode (area that can be energized) increases dramatically. Therefore, when the battery current collector plate is brought into contact with this flat surface, the current collector plate can be welded to the winding body in a good state, the contact area between the two is increased, and the current collection efficiency is increased. The characteristics are remarkably improved.

  The said structure WHEREIN: The core exposed part which the active material is not applied to at least one edge of the width direction is formed also in the said 2nd electrode, The said winding body preparation step is a said 1st electrode on one surface. The core exposed portion of the second electrode protrudes beyond the separator width, and the core exposed portion of the second electrode protrudes beyond the separator width on the other surface, and the tapping step includes the step of The winding body in which the core body exposed portion protrudes from the one surface and the other surface can be moved up and down in the axial direction to tapping the one surface and the other surface.

  When this method is used, a flat surface can be formed also on the second electrode, and the current collection efficiency is increased at both electrodes, so that the high-rate discharge characteristics can be further improved.

  The said structure WHEREIN: It can be set as the structure further provided with the fold line formation step which forms a fold line in the core body exposed part of the 1st electrode used at a wound body preparation step before the said winding body preparation step.

  When this method is used, the current collector is smoothly bent toward the center of the battery in the tapping step with the fold line as a base axis, so that a flat surface convenient for electrical connection can be formed.

  In the above configuration, after the winding body preparation step and before the tapping step, a pressure from the outer periphery of the winding body toward the center of the core body exposed part is applied to the winding body from which the core body exposed part protrudes, It can be set as the structure further provided with the bending auxiliary groove formation step which forms a some groove | channel in a body exposure part radially.

  When this method is used, the bending direction due to tapping is induced in the direction deformed by the pressure from the outer periphery of the winding body toward the center, and thus a flat surface convenient for smooth electrical connection can be formed. The number of bending assist grooves is preferably 3 or more, more preferably 4 or more.

  The present invention relating to a method for manufacturing a battery for solving the above-mentioned problems is to weld a current collecting plate for taking out current from the spiral electrode body to the one surface of the spiral electrode body obtained by the method described above. It is characterized by.

  According to this configuration, since the contact area that can be used for electrical connection is much larger than the conventional tab, the flat surface of the spiral electrode body can dramatically increase the contact area with the current collector plate of the battery. This significantly improves the high rate discharge characteristics.

  As this welding, resistance welding, ultrasonic welding, or welding with a high energy beam can be used. As the welding with the high energy beam, a laser beam or an electron beam can be used.

  As described above, according to the present invention, the spiral electrode body and the current collector plate can be welded in a good state by a simple method, and a battery excellent in high rate discharge characteristics can be manufactured with a high yield.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory view showing steps for producing a spiral electrode body, FIG. 2 is an explanatory view showing a tapping process, and FIG. 3 is a view showing a welding process between the electrode body and a current collector plate.

(Winding body production step)
As shown in FIG. 1A, a fold line is formed by using a roller on a negative electrode (first electrode) in which a core exposed portion not coated with an active material is formed on at least one edge in the width direction. To do. Thereafter, as shown in FIG. 1 (b), the negative electrode, the separator, and the positive electrode are overlapped with the core exposed portion of the negative electrode protruding beyond the separator width forward in the width direction. It winds in the direction and produces a wound body in which the core exposed portion of the negative electrode protrudes on one surface (see FIG. 1C).

(Bending auxiliary groove forming step)
Thereafter, a pressure from the outer periphery of the winding body toward the center is applied to one surface of the winding body from which the core body exposed portion protrudes, and a plurality of grooves are formed radially on the one surface (FIG. 2B). (See (c)).

(Tapping step)
Thereafter, tapping is performed about 50 times from a height of about 20 mm. (Refer to FIG. 2 (d).) Since the radial bending auxiliary groove is provided, the negative electrode core protruding from one surface is not refracted radially outward, and the whole is directed almost uniformly toward the radially inner side. It will be plastically deformed so that it will be bent, and a flat surface will be formed as a whole while producing some wrinkles. Thereby, the spiral electrode body is completed (see FIG. 2E).

  Thereafter, as shown in FIG. 3, the flat surface of the spiral electrode body and the current collector plate are welded. Thereafter, the electrode body is inserted into the battery can, the current collector plate and the battery can are laser welded, the electrolyte is then injected, the opening is sealed, and the battery is completed.

(Example)
Hereinafter, the present invention will be described more specifically with reference to examples.

(Preparation of positive electrode)
A positive electrode active material slurry made of lithium cobalt oxide was prepared by mixing a conductive agent made of carbon, a binder made of polyvinylidene fluoride, and N-methylpyrrolidone. The positive electrode active material slurry was applied to both surfaces of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm, dried and rolled to obtain a positive electrode plate having a size of L2050 mm × W50 mm × T 0.09 mm on which a positive electrode material layer was formed. Obtained.

(Preparation of negative electrode)
A negative electrode active material slurry made of artificial graphite, a binder made of polyvinylidene fluoride, and N-methylpyrrolidone were mixed. This negative electrode active material slurry was applied to both sides of a negative electrode core made of a copper foil having a thickness of 10 μm, leaving a non-coated portion with a width of 7 mm on one side edge, dried and rolled, and the negative electrode material layer was A formed negative electrode plate having dimensions of L2150 mm × W60 mm × T0.08 mm was obtained. Thereafter, a bent base line was formed with a roller as shown in FIG.

(Winding body production step)
The positive electrode plate and the negative electrode plate were placed in a state of facing each other (see FIG. 1B) with a separator made of a microporous polyethylene film having a thickness of 22 μm (see FIG. 1B), and wound to prepare a wound body.

(Bending auxiliary groove forming step)
As shown in FIGS. 2 (b) and 2 (c), pressure toward the center from the outer periphery of the winding body is applied to one surface of the winding body from which the core exposed portion protrudes, and the eight folding auxiliary grooves are formed in a radial pattern. Formed.

(Tapping step)
Thereafter, the electrode body was put into a cylindrical jig having a diameter about 1 mm larger than the electrode body, and tapping was performed 50 times from a position having a height of 20 mm (see FIG. 2D). Thereby, the negative electrode current collector plate was plastically deformed to form a flat surface (see FIG. 2E).

(welding)
As shown in FIG. 3, in a state where the flat surface of the spiral electrode body on which the flat surface is formed is pressed against the current collector plate so as to press the flat surface, a plurality of locations on the surface of the current collector plate are arranged. The current collector plate and the flat portion were laser welded by irradiating a laser beam radially from the center to the outer periphery. The welding conditions are as follows.

  The separator is pressed with a force that does not shift, and is welded at a frequency of 150 Hz, a pulse laser output of 1.0 kW, and a machining speed of 200 mm / S using a KAGOKA KLY-HP300β YAG laser.

(Battery assembly)
After the work-in-process with the current collector plate joined is inserted into the battery can, it is welded to the outer can and the battery lid, stored with the electrolyte, vacuum impregnated, and sealed with the battery lid. Produced.

(Comparative example)
A battery according to a comparative example was fabricated in the same manner as in the example except that the bending auxiliary groove forming step and tapping were not performed.

  As the evaluation, after the appearance was confirmed, the current collector plate was pulled and peeled to confirm the state of the current collector plate and the remaining copper foil (negative electrode current collector) on the current collector plate. Moreover, the cross section was cut | disconnected and the welding state was confirmed. The results are shown in Table 1 below.

  From Table 1 above, the copper foil remains on the current collector plate in all the batteries in the examples, whereas in the comparative example, the current collector plate is burnt and perforated in all of the batteries. It can be seen that the remaining foil also varies.

  This is considered as follows. In the embodiment, since the flat surface is formed by tapping, the current collector and the current collector plate are reliably welded. For this reason, when the current collector plate is peeled off, the welded current collector remains on the current collector plate. On the other hand, in the comparative example, since the flat surface is not formed, the current collector and the current collector plate are not sufficiently welded, the current collector plate is burnt, the perforation occurs, and the copper foil remaining at the welded portion also remains. Variations occur.

  In the embodiment, since the flat surface is formed, the flat surface and the current collector plate are reliably welded. On the other hand, in the comparative example, since the spiral electrode body and the current collector plate are not sufficiently welded, the current collector plate melted by the laser irradiation falls into the gap between the electrode plates of the electrode body, causing charring and perforation.

  From the above, it can be seen that the manufacturing method of the present invention enables stable welding between the current collector and the current collector plate, and is effective in improving battery performance, quality and productivity.

  In addition, although the negative electrode was bent in the said Example, the structure which bends a positive electrode may be sufficient and the structure which both bends may be sufficient. In addition, the present invention can be applied to all batteries including a spiral electrode body, and may be a primary battery or a secondary battery.

  As described above, according to the present invention, a battery excellent in high-rate discharge characteristics can be provided at a low cost, and thus has great industrial significance.

FIG. 1 is an explanatory view illustrating a winding step of the battery of the present invention. FIG. 2 is an explanatory view for explaining the tapping step of the battery of the present invention. FIG. 3 is an explanatory view showing a laser welding method for the battery of the present invention.

Claims (7)

A first electrode in which an active material is applied to a band-shaped electrode core; and a second electrode in which the first electrode is an electrode having a different polarity and the active material is applied to a band-shaped electrode core; In the method of manufacturing a spiral electrode body that is wound through a separator to form a spiral electrode body,
A core exposed portion not coated with an active material is formed on at least one edge in the width direction of the first electrode,
The first electrode, the separator, and the second electrode are overlapped with the core exposed portion of the first electrode protruding forward in the width direction beyond the separator width, and the three parties are wound in the longitudinal direction. A winding body manufacturing step for manufacturing a winding body in which the core exposed portion of the first electrode protrudes on one surface;
A tapping step in which the winding body is moved up and down in the axial direction, and the one surface is tapped to bend the protruding core body exposed portion to the main body side of the winding body to flatten the one surface;
A process for producing a spiral electrode body, comprising: In the manufacturing method of the spiral electrode body according to claim 1,
A core exposed portion not coated with an active material is formed on at least one edge in the width direction also in the second electrode,
In the winding body manufacturing step, the core body exposed portion of the first electrode protrudes beyond the separator width on one side, and the core body exposed portion of the second electrode protrudes beyond the separator width on the other side. A step of making a body,
The tapping step is a step of tapping the one surface and the other surface by vertically moving the winding body in which the core body exposed portion protrudes from the one surface and the other surface in the axial direction.
A method of manufacturing a spiral electrode body, characterized in that In the manufacturing method of the spiral electrode body according to claim 1 or claim 2,
Before the winding body manufacturing step, further comprising a fold line forming step of forming a fold line in the core exposed portion used in the winding body manufacturing step,
A method of manufacturing a spiral electrode body. In the manufacturing method of the spiral electrode body according to claim 1 or claim 2,
After the winding body manufacturing step and before the tapping step, a pressure from the outer periphery of the winding body toward the center of the core body exposed portion acts on the core body exposed portion of the winding body from which the core body exposed portion protrudes. And further comprising a bending auxiliary groove forming step for forming a plurality of grooves radially in the core exposed portion,
A method of manufacturing a spiral electrode body. A current collector plate for taking out current from the spiral electrode body is welded to the core body exposed portion of the spiral electrode body obtained by the method according to any one of claims 1 to 4.
A method for producing a sealed battery, comprising: In the manufacturing method of the sealed battery according to claim 5,
The welding is resistance welding, ultrasonic welding, or welding with high energy rays.
A method for producing a sealed battery, comprising: In the manufacturing method of the sealed battery according to claim 6,
The high energy beam is a laser beam or an electron beam;
A method for producing a sealed battery, comprising: