JP5091507B2 - Winding battery - Google Patents

Description

  The present invention relates to a wound battery, and more particularly, to a wound battery having an electrode group in which a positive electrode and a negative electrode are wound around an axis via a separator.

  A wound battery has an electrode group in which a positive electrode and a negative electrode are wound through a separator in order to increase the electrode area in order to achieve high capacity and high output. In general, when the electrode group is formed, the positive electrode, the negative electrode, and the separator are wound under tension in order to suppress the collapse of the electrode group due to vibration during use of the battery. It will hang. On the other hand, since the positive electrode and the negative electrode are each coated with a mixture containing an active material on the current collector, and it is difficult to make a small starting portion, the central portion of the electrode group is formed in a hollow shape. The electrode group may be deformed by the winding pressure. In order to avoid this, an axial core is disposed at the winding center of the electrode group.

  As a method of forming such an electrode group, a method of directly winding a positive electrode, a negative electrode, and a separator around a winding shaft provided in an electrode group manufacturing apparatus (winding machine), or a cylindrical shape on a winding shaft There is a method in which a shaft core is attached and a positive electrode, a negative electrode, and a separator are wound around the shaft core. That is, in the former method, only the separator is wound on the winding shaft directly for several turns, and then wound so that the positive electrode and the negative electrode face each other via the separator. After winding, the electrode group is removed from the winding shaft, and the shaft core is inserted into the central portion of the electrode group. In the latter method, the end of the separator is bonded and fixed to the shaft core attached to the winding shaft with an adhesive tape or the like, and only the separator is wound several times, and then the positive electrode, the negative electrode, and the separator are wound ( For example, see Patent Document 1).

JP 2001-185220 A

  However, in the method of inserting the shaft core after winding, when the electrode group is removed from the electrode group manufacturing apparatus or when the shaft core is inserted after removal, the electrode group is caused by friction between the shaft core and the starting portion of the separator. In some cases, there is a problem such as occurrence of a gap on the center side. For this reason, productivity of an electrode group and by extension, a winding type battery will fall. Further, in a state where it is detached from the winding shaft, the shaft core is not inserted, and the center side of the electrode group is supported only by the separator at the beginning of the winding, so that it is deformed by the winding pressure applied to the electrode group. Sometimes. On the other hand, in the method of winding the shaft core on the winding shaft, a device, an adhesive tape, or the like for bonding and fixing the end of the separator to the shaft core is required. Since the bonding step is performed, the work of forming the electrode group becomes complicated and the productivity of the wound battery decreases.

  In view of the above-described case, an object of the present invention is to provide a wound battery in which an electrode group can be formed without going through a bonding step between a shaft core and a separator, and productivity is improved.

In order to solve the above problems, the present invention provides a wound battery having an electrode group in which a positive electrode and a negative electrode are wound around a shaft core via a separator, wherein the shaft core is a pair of members fitted to each other. It is comprised, The said separator has penetrated between said one pair of members, It is characterized by the above-mentioned.

In the present invention, since the axis core of the electrode group is constituted by a pair of members fitted to each other, and the separator penetrates between the pair of members, the separator between the pair of members is formed when the electrode group is formed. The positive electrode and the negative electrode are supplied from both sides of the shaft core, and the positive electrode and the negative electrode are wound through a separator that penetrates between a pair of members. Since the electrode group can be formed without the need, productivity of the wound battery can be improved.

In the present invention, if the shaft core is composed of two members having the same shape, member management can be facilitated. If the shaft core is hollow, the positive electrode and the negative electrode can be wound by inserting the winding shaft of the winding machine into the shaft core. Further, if the shaft core has a fitting portion at both ends in the longitudinal direction, and the fitting portion is fitted by unevenness in the longitudinal direction of the shaft core, the fitting portion intersects the longitudinal direction of the shaft core. In order to resist the external force in the direction of turning, it is possible to prevent the shaft core from being unfitted by the tension of the separator during winding . It is preferred that more than the thickness of the gap of the separator is formed between a pair of members. Further, the electrode group may be wound so that the positive electrode and the negative electrode face each other through a separator penetrating between a pair of members. At this time, the electrode group can be wound from a substantially central portion in the longitudinal direction of the separator.

According to the present invention, the axial core of the electrode group is composed of a pair of members fitted to each other, and the separator penetrates between the pair of members. The separator is sandwiched between the positive electrode and the negative electrode from both sides of the shaft core, and the positive electrode and the negative electrode are wound through a separator that penetrates between a pair of members. Since an electrode group can be formed without passing through, the effect that the productivity of a winding type battery can be improved can be acquired.

  Embodiments in which the present invention is applied to a cylindrical lithium ion secondary battery will be described below with reference to the drawings.

(Constitution)
As shown in FIG. 1, the cylindrical lithium ion secondary battery 20 of the present embodiment includes an electrode group 6 wound in a spiral shape so that the strip-like positive and negative electrode plates face each other with a separator interposed therebetween. The electrode group 6 is made of nickel-plated steel and accommodated in a bottomed cylindrical battery case 7. That is, the lithium ion secondary battery 20 is a wound battery.

  A shaft core 1 made of polypropylene resin is used at the winding center of the electrode group 6. As shown in FIG. 2, the shaft core 1 includes two (one pair) shaft core members 1a and 1b. The shaft core members 1a and 1b are formed in the same shape. The shaft core member 1a (the same applies to the shaft core member 1b) is formed in a circular arc shape in cross section. A fitting portion 22 having a cylindrical shape (a cross-sectional shape including a circular arc-shaped portion of the shaft core member 1a) is formed at one end portion in the longitudinal direction of the shaft member 1a, and a projecting shape is formed at the other end portion. The fitting part 23 is formed. The inner peripheral side of the fitting portion 22 of the shaft core member 1a is cut out with an inner diameter larger than the inner diameter of the cross-section arc-shaped portion of the shaft core member 1a on the side opposite to the arc-shaped section. ing. On the other hand, the fitting portion 23 of the shaft core member 1a protrudes in the longitudinal direction so that the inner peripheral side of the portion having an arcuate cross section is fitted to the cut-out position of the fitting portion 22 of the shaft core member 1b. For this reason, the unevenness | corrugation of a longitudinal direction is formed in the both ends of axial core member 1a, 1b. That is, the fitting parts 22 and 23 have a consensus structure. The shaft core 1 is formed by alternately combining the shaft core members 1a and 1b in the longitudinal direction and fitting the fitting portions 22 and 23 together. In other words, in the shaft core 1, the shaft core members 1a and 1b are fitted to each other at both ends in the longitudinal direction.

  As shown in FIG. 3, the fitting portion 23 of the shaft core member 1a is fitted into the fitting portion 22 of the shaft core member 1b, and the fitting portion 23 of the shaft core member 1b becomes the fitting portion 22 of the shaft core member 1a. By fitting, the substantially cylindrical shaft core 1 is formed. In other words, the shaft core 1 is formed by fitting the concaves and convexes formed at both longitudinal ends of the shaft core members 1a and 1b. Since the shaft core members 1a and 1b are both arc-shaped in cross section, the shaft core 1 fitted with these members has a hollow portion T formed in the longitudinal direction. Further, a gap S is formed in the longitudinal direction between the shaft core member 1a and the shaft core member 1b for allowing the separator to pass therethrough when the electrode group is manufactured. The gap S is formed more than the thickness of the separator. In order to form the gap S, the cross-sectional shapes of the shaft core members 1a and 1b are strictly formed in an arc shape slightly smaller than half of the annular cross section of the fitting portion 22.

  As shown in FIG. 1, on the upper side of the electrode group 6, an annular positive electrode current collecting ring 4 for collecting the electric potential from the positive electrode plate is disposed on a substantially extension line of the shaft core 1. The positive electrode current collecting ring 4 is fixed to the upper end portion of the shaft core 1. The edge part of the positive electrode lead piece 2 led out from the positive electrode plate is joined by ultrasonic welding to the peripheral edge of the flange part integrally protruding from the periphery of the positive electrode current collecting ring 4. Above the positive electrode current collecting ring 4, a disc-shaped battery lid 12 is provided that incorporates a safety valve and serves as a positive electrode external terminal. One end of a positive electrode lead 9 is joined to the upper part of the positive electrode current collecting ring 4, and the other end of the positive electrode lead 9 is joined to the lower surface of the battery lid 12.

  On the other hand, an annular negative electrode current collecting ring 5 for collecting electric potential from the negative electrode plate is disposed below the electrode group 6. The outer peripheral surface of the lower end portion of the shaft core 1 is fixed to the inner peripheral surface of the negative electrode current collecting ring 5. The end of the negative electrode lead piece 3 led out from the negative electrode plate is joined to the outer peripheral edge of the negative electrode current collecting ring 5 by welding. The lower part of the negative electrode current collection ring 5 is joined to the inner bottom part of the battery container 7 which also serves as a negative electrode external terminal via a negative electrode lead 8 by welding.

  The battery lid 12 is caulked and fixed to the upper part of the battery container 7 via an insulating and heat resistant gasket 10 made of polypropylene resin or the like. For this reason, the inside of the lithium ion secondary battery 20 is sealed. In addition, a non-aqueous electrolyte is injected into the battery container 7. As the non-aqueous electrolyte, a solution obtained by dissolving lithium hexafluorophosphate at a concentration of 1 mol / L in a mixed solvent such as ethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate is used.

  In the electrode group 6, the positive electrode plate and the negative electrode plate are wound around the shaft core 1 through a microporous separator W5 made of polyethylene or the like so that the both electrode plates do not directly contact each other. The separator W5 has a thickness in the range of about 20 to 50 μm and a width that is greater than the width of the positive electrode plate and the negative electrode plate. The positive electrode lead piece 2 and the negative electrode lead piece 3 are arranged on both end surfaces of the electrode group 6 opposite to each other. Insulation coating is applied to the entire circumference of the collar peripheral surface of the electrode group 6 and the positive electrode current collecting ring 4 in order to prevent electrical contact between the electrode group 6 and the battery container 7. The number of windings is adjusted so that the maximum diameter portion of the electrode group 6 becomes an insulating coating existing portion, and the maximum diameter is set slightly smaller than the inner diameter of the battery container 7.

  The positive electrode plate constituting the electrode group 6 has an aluminum foil W1 as a positive electrode current collector. A positive electrode mixture containing a lithium transition metal composite oxide as a positive electrode active material is applied to both surfaces of the aluminum foil W1 substantially evenly. In addition to the positive electrode active material, a carbon powder conductive material such as graphite and a binder (binder) such as polyvinylidene fluoride (hereinafter abbreviated as PVDF) are blended in the positive electrode mixture. When the positive electrode mixture is applied to the aluminum foil W1, the viscosity is adjusted with a dispersion solvent such as N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP). An uncoated part (plain part) of the positive electrode mixture is formed on one side edge of the aluminum foil W1 in the longitudinal direction (winding direction). The uncoated part is cut out in a comb shape, and the positive electrode lead piece 2 is formed in the notch remaining part.

  On the other hand, the negative electrode plate has a copper foil W3 as a negative electrode current collector. A negative electrode mixture containing a powder of carbon material such as graphite capable of reversibly occluding and releasing lithium ions as a negative electrode active material is coated on both surfaces of the copper foil W3 substantially evenly. In addition to the negative electrode active material, a binder such as PVDF is blended in the negative electrode mixture. When the negative electrode mixture is applied to the copper foil W3, the viscosity is adjusted with a dispersion solvent such as NMP. An uncoated portion of the negative electrode mixture is formed on the side edge on one side in the longitudinal direction of the copper foil W3, as in the case of the positive electrode plate, and the negative electrode lead piece 3 is formed. The length of the negative electrode plate is such that when the positive electrode plate and the negative electrode plate are wound, the positive electrode plate does not protrude from the negative electrode plate in the winding direction at the innermost winding and outermost winding. It is set longer than the length. In addition, the width of the negative electrode mixture application portion is such that the positive electrode mixture application portion does not protrude from the negative electrode mixture application portion in the direction perpendicular to the winding direction (longitudinal direction of the shaft core 1). It is set longer than the width of.

(Battery assembly)
In the assembly of the lithium ion secondary battery 20, first, the produced positive and negative electrode plates are wound around the shaft core 1 through a separator to produce the electrode group 6. The electrode group 6 is manufactured as follows using a winding machine (electrode group manufacturing apparatus) equipped with a winding shaft.

  The winding shaft of the winding machine is formed in a U shape in which a rod-like projecting portion is divided into two parts, and the base portion of the U shape is fixed to the rotary drive shaft of the winding machine. A hollow portion T of the shaft core 1 is formed so that a protruding portion of the winding machine can be inserted. The shaft core member 1a is mounted on the winding machine through the winding shaft through the fitting portion 22 so that the fitting portion 22 of the shaft core member 1a is on the base side of the winding shaft. At this time, the shaft core member 1a is mounted so as to be positioned at one of the U-shaped protruding portions of the winding shaft. After inserting the separator W5 into the U-shaped gap of the winding shaft, the fitting portion 23 of the shaft core member 1b is fitted to the fitting portion 22 of the shaft core member 1a (the U-shape of the winding shaft). The shaft core member 1b is attached to the winding machine (so as to be positioned on the other of the protruding portions). The shaft core 1 is formed by fitting the fitting portions 22 and 23 of the shaft core members 1a and 1b, respectively. At this time, the separator W5 takes into consideration the length necessary for winding a few turns ahead at the beginning of winding to the shaft core 1 and the length necessary for covering the outermost periphery of the electrode group 6 at the end of rolling. Prepare on both sides of 1 (winding shaft) to be sufficiently longer than the length of the positive and negative electrode plates.

  4A, when the shaft core 1 (shaft core members 1a and 1b) and the separator W5 are mounted on the winding shaft 30 of the winding machine, the winding shaft 30 is placed in the hollow portion T of the shaft core 1. The inserted state is reached, and the separator W5 passes through the shaft core 1 (and the winding shaft 30). When the winding shaft 30 is rotationally driven in this state, the separator W5 starts to be wound around the shaft core 1. After winding only the separator W5 at the beginning of rolling, the positive electrode plate and the negative electrode plate are appropriately opposed to the positive electrode mixture coating surface and the negative electrode mixture coating surface. The electrode group 6 is manufactured by sequentially inserting the negative electrode lead pieces 3 so as to be positioned in opposite directions. For this reason, the electrode group 6 is formed by being wound from a substantially central portion in the longitudinal direction of the separator W5. When the separator W5 starts to be rolled, the gap S formed between the shaft core members 1a and 1b is narrowed by the winding pressure, and the outer peripheral surface of the shaft core member 1a and the outer peripheral surface of the fitting portion 22 of the shaft core member 1b. And a slight level difference occurs (the same applies to the outer peripheral surface of the shaft core member 1b and the outer peripheral surface of the fitting portion 22 of the shaft core member 1a), but the step can be eliminated by leading the separator W5, In addition, since both the positive electrode plate and the negative electrode plate are formed to be smaller than the width of the separator, there is no trouble at the step.

  As shown in FIG. 4 (B), after separating the separator W5, the negative electrode plate is pivoted from one side of the separator W5 (lower side in FIG. 4 (B)) and from one side (left side) of the shaft core 1. Insert in the direction toward the core 1 (arrow N direction). The winding shaft 30 is rotationally driven in the winding direction (arrow A direction), and the positive electrode plate is inserted when the negative electrode plate is wound about a half turn (when the tip of the negative electrode plate reaches the right side). The positive electrode plate is inserted in the direction (arrow P direction) from the other side (upper side) of the separator W5 to the axis 1 from the other side (right side) of the axis 1. For this reason, the positive electrode mixture coating surface of the positive electrode plate and the negative electrode mixture coating surface of the negative electrode plate appropriately face each other. In other words, the electrode group 6 is supplied and wound from both sides of the shaft core 1 so that the positive electrode plate and the negative electrode plate face each other through the separator W5 penetrating between the shaft core members 1a and 1b. is there.

  After all of the positive electrode plate and the negative electrode plate are wound, the separator W5 is wound about two to three times at the end of the winding so that the electrode is not exposed at the outermost periphery of the electrode group 6. In this state, the electrode group 6 is pulled out from the winding shaft 30 together with the shaft core 1 while being held so as not to be unwound, and the electrode group 6 is produced by scratching the joint portion of the outermost separator with an adhesive tape or the like. Complete. At this time, since the shaft core 1 is in the central portion of the electrode group 6, the electrode group 6 can be removed without being deformed while maintaining the winding pressure.

  A resin insulating plate having the same diameter as that of the electrode group 6 is disposed at both ends of the produced electrode group 6, and the positive electrode lead piece 2 and the negative electrode lead piece 3 respectively led to the both end surfaces of the electrode group 6 are collected into the positive electrode. After welding to the current ring 4 and the negative current collector ring 5, the electrode group 6 is inserted into the battery container 7 with the negative current collector ring 5 facing the bottom. A welding rod is inserted into the hollow portion T formed in the shaft core 1, and the negative electrode lead 8 previously welded to the negative electrode current collecting ring 5 is joined to the inner bottom portion of the battery container 7 by resistance welding. Grooving is performed slightly on the bottom side from the opening of the battery container 7, and the other end of the positive electrode lead 9 whose one end is previously welded to the positive electrode current collecting ring 4 is joined to the lower surface of the battery lid 12 by welding. In order to remove moisture adhering to the electrode group 6, the battery container 7, etc., vacuum drying is performed at 60 ° C. for 20 hours with the gasket 10 attached to the upper side of the grooved portion. After vacuum drying, a non-aqueous electrolyte is poured into the battery container 7. The non-aqueous electrolyte is injected in a glove box substituted with argon in order to prevent reattachment of moisture. After injecting the non-aqueous electrolyte, the battery lid 12 is caulked and fixed to the top of the battery container 7 to complete the assembly of the lithium ion secondary battery 20.

(Action etc.)
Next, the operation and the like of the cylindrical lithium ion secondary battery 20 of the present embodiment will be described focusing on the shaft core 1.

  In the lithium ion secondary battery 20 of the present embodiment, the shaft core 1 of the electrode group 6 is composed of a pair of shaft core members 1a and 1b fitted together. When the electrode group 6 is manufactured, the separator W5 is passed between the shaft core members 1a and 1b, and the positive electrode plate and the negative electrode plate are wound. For this reason, the electrode group 6 can be easily produced without adhering the starting portion of the separator W5 to the shaft core 1. This eliminates the need for the work required for the conventional bonding process, so that the productivity of the electrode group 6 and, in turn, the lithium ion secondary battery 20 can be improved. Also, in the production of the conventional electrode group, after the positive electrode plate and the negative electrode plate are wound directly on the winding shaft of the winding machine, the electrode group is removed from the winding shaft, and the shaft core is inserted into the central portion of the electrode group. The For this reason, when the electrode group is removed from the winding shaft or when the shaft core is inserted, the positive electrode plate and the negative electrode plate may be displaced at the center of the electrode group, resulting in an increase in the defect rate (productivity decrease). ). On the other hand, in the lithium ion secondary battery 20 of the present embodiment, since the positive electrode plate and the negative electrode plate are wound around the shaft core 1 attached to the winding shaft 30, the electrode group 6 is produced. It is possible to reduce the defect rate by preventing the occurrence of wobbling without inserting the shaft core later.

  Further, since the separator W5 penetrates between the shaft core members 1a and 1b, when the separator W5 starts to be rolled when the electrode group 6 is manufactured, the shaft core members 1a and 1b are split open by the tension of the separator W5 ( Apply external force to release the fitting. In the present embodiment, the shaft core 1 is configured by fitting fitting portions 22 and 23 formed on the shaft core members 1a and 1b, respectively. That is, the shaft core members 1a and 1b are fitted by the unevenness in the longitudinal direction. For this reason, since the fitted fitting parts 22 and 23 resist the external force due to the tension of the separator W5, the positive electrode plate and the negative electrode plate are surely wound without the shaft core 1 being detached from the winding machine, and the electrode group 6 is produced. can do.

  Furthermore, in this embodiment, the fitting parts 22 and 23 of the shaft core members 1a and 1b are formed at both ends in the longitudinal direction, and a gap S is formed in the longitudinal direction between the shaft core members 1a and 1b. Therefore, the shaft core members 1a and 1b can be reliably fitted without preventing the separator W5 from penetrating the shaft core 1 (between the shaft core members 1a and 1b), and the shape of the shaft core 1 is maintained. can do. In the present embodiment, the gap S between the shaft core members 1a and 1b is formed to be equal to or greater than the thickness of the separator W5. For this reason, it can be easily inserted between the shaft core members 1a and 1b without damaging the separator W5.

  Furthermore, in this embodiment, the shaft core members 1a and 1b constituting the shaft core 1 are formed in the same shape. In other words, in the shaft core 1 fitted with the shaft core members 1a and 1b, the shaft core member 1a and the shaft core member 1b have a point-symmetric positional relationship with respect to the center point (center of gravity) of the shaft core 1. For this reason, it is not necessary to produce members having different shapes, so that the cost can be reduced and member management can be facilitated. Further, the shaft core members 1a and 1b are formed in a circular arc shape in cross section. For this reason, since the hollow part T is formed in the axial core 1 which fitted the axial core members 1a and 1b, the winding axis | shaft of the existing winding machine can be inserted, and the electrode group 6 can be produced, and manufacture It is possible to suppress an increase in cost because it is not necessary to newly install or modify equipment.

  In the present embodiment, an example in which the shaft core 1 is cylindrical has been described, but the present invention is not limited to this, and may be, for example, a polygonal shape. Moreover, there is no restriction | limiting in the shape also about the hollow part T formed in the shaft core 1, What is necessary is just to be able to be mounted on the winding shaft 30 of the winding machine.

  Moreover, in this embodiment, although the fitting parts 22 and 23 were formed in the both ends of the shaft member 1a and 1b, respectively, the example which hold | maintains the shape of the shaft core 1 at the time of preparation of the electrode group 6 was shown. The present invention is not limited to this. For example, the shape of the shaft core 1 may be maintained by providing a mechanism for clamping the shaft core 1 from the outer peripheral side on the winding machine side. Considering the mounting of the shaft core 1 to the winding device and the modification of the equipment, it is possible to expect an improvement in productivity by maintaining the shape of the shaft core 1 by the shape of the shaft core members 1a and 1b. Further, in addition to forming the fitting portions at both end portions of the shaft core members 1a and 1b, for example, portions having an arcuate cross section may be formed as a consensus structure and may be fitted to each other.

  Furthermore, in this embodiment, although the example which makes the fitting part 22 of the axial core members 1a and 1b cylindrical and the fitting part 23 protruded was shown, this invention is restrict | limited to the shape of a fitting part. Instead, it is only necessary to form and fit the concave and convex portions in the longitudinal direction of the shaft core members 1a and 1b. For example, both the shaft core members 1a and 1b may be formed with fitting portions 23 at both ends so that an annular ring member is fitted. Moreover, in this embodiment, although the example which produces the electrode group 6 without passing through an adhesion | attachment process by letting the separator W5 penetrate between the axial core members 1a and 1b was shown, this invention is restrict | limited to this. is not. You may make it adhere | attach the separator W5 penetrated between the shaft core members 1a and 1b, and the shaft core 1. FIG.

  Furthermore, in the present embodiment, an example has been shown in which the electrode group 6 is wound from a substantially central portion in the longitudinal direction of the separator W5 that passes between the shaft core members 1a and 1b. In this way, considering that the separator is wound from a substantially central portion in the longitudinal direction, the shaft core can be constituted by a single cylindrical member. For example, the electrode group can be formed without going through the bonding process between the shaft core and the separator, and when it is intended to obtain a wound battery with improved productivity, it is composed of one member. A gap (slit) for penetrating the separator is formed in the longitudinal direction of the cylindrical shaft core, the separator is penetrated through the gap, and the positive electrode plate and the negative electrode plate are opposed to each other through the separator penetrating the shaft core. The electrode group and thus the wound battery can be manufactured by winding each of the above. In this way, since the electrode group is wound and formed from a substantially central portion in the longitudinal direction of the separator, the electrode group can be formed without going through an adhesion process between the shaft core and the separator. The productivity of the rotary battery can be improved. Further, in addition to winding from the substantially central portion in the longitudinal direction of the separator W5, winding may be performed from one end portion in the longitudinal direction of the separator W5. At this time, by sandwiching the two separators W5 on both sides of the shaft core, the positive electrode plate and the negative electrode plate can be wound so as to face each other with the separator W5 interposed therebetween.

  Furthermore, in the lithium ion secondary battery 20 of the present embodiment, the lithium transition metal composite oxide as the positive electrode active material, graphite as the negative electrode active material, graphite as the conductive material, and lithium hexafluorophosphate as a mixed solvent as the nonaqueous electrolyte solution However, the present invention is not limited to these materials, and materials generally used for lithium ion secondary batteries may be used.

  Further, in the present embodiment, the cylindrical lithium ion secondary battery 20 is exemplified, but the present invention is not limited to this, and can be generally applied to a wound battery in which positive and negative electrode plates are wound. Is possible. Examples of such a wound secondary battery include a nickel hydrogen battery, a lead storage battery, and a nickel cadmium battery. Further, the shape of the battery is not particularly limited. For example, the battery may have a square shape in addition to the cylindrical shape.

  The present invention can form an electrode group without going through the bonding step between the shaft core and the separator, and contributes to the manufacture and sale of the wound battery in order to provide a wound battery with improved productivity. And has industrial applicability.

It is sectional drawing of the cylindrical lithium ion secondary battery of embodiment to which this invention is applied. It is a perspective view which decomposes | disassembles and shows the two axial core members which comprise the axial core used for the cylindrical lithium ion secondary battery of embodiment. It is a perspective view which shows the state which two axial core members which comprise the axial core of the cylindrical lithium ion secondary battery of embodiment fit. It is sectional drawing which shows typically the positional relationship of a separator when producing the electrode group of a cylindrical lithium ion secondary battery, a positive / negative electrode plate, and an axial core, (A) is when a separator penetrates an axial core. (B) shows a state when the positive and negative electrode plates are respectively arranged on both sides of the shaft core after winding the separator several times.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft core 1a, 1b Shaft core member 6 Electrode group 20 Cylindrical lithium ion secondary battery (winding type battery)
22, 23 Fitting part W5 Separator

Claims (7)

In a wound battery having an electrode group in which a positive electrode and a negative electrode are wound around a shaft core via a separator, the shaft core is composed of a pair of members fitted to each other . A wound battery characterized by penetrating between the members .   The wound battery according to claim 1, wherein the shaft core is composed of two members having the same shape.   The wound battery according to claim 1 or 2, wherein the shaft core is hollow.   The said axis | shaft has a fitting part in the longitudinal direction both ends, The said fitting part fits by the unevenness | corrugation of the longitudinal direction of the said shaft core, The scissors of Claim 1 characterized by the above-mentioned. Revolving battery. Said between a pair of members, wound type battery of claim 1, wherein a thickness of more gaps of the separator in the longitudinal direction is formed. 6. The electrode group according to any one of claims 1 to 5 , wherein the electrode group is wound so that the positive electrode and the negative electrode face each other through a separator penetrating the pair of members. The wound battery according to claim 1. The wound battery according to claim 6 , wherein the electrode group is wound from a substantially central portion in the longitudinal direction of the separator.

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