JP2014137907A - Secondary battery and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery in which an electrode body can be manufactured easily without using the welding, and high performance can be attained by preventing misalignment of the negative electrode, the positive electrode, and the separator of the electrode body, and suppressing short circuit and weakening of power collection due to misalignment, thereby reducing voltage drop.SOLUTION: A secondary battery 1 includes a battery container 3 having a negative electrode collector 31 and a positive electrode collector 32 arranged to face each other, and an electrode body 2 being housed therein. The electrode body 2 is formed by winding a sheet-like positive electrode 22 and a sheet-like negative electrode 21 spirally with a separator 23 interposed therebetween. The separator 23 is interposed between the positive electrode 22 and negative electrode 21, and consists of one sheet folded to cover the other end 21b of the negative electrode 21 on the opposite side in the projecting direction, and folded to cover the other end 22b of the positive electrode 22 on the opposite side in the projecting direction. One end 21a of the negative electrode 21 in the projecting direction abuts against the negative electrode collector 31, and one end 22a of the positive electrode 22 on the projecting direction side abuts against the positive electrode collector 32.

Description

  The present invention relates to a secondary battery and a method for manufacturing the same.

  Conventionally, secondary batteries are used in various products such as mobile phones, mobile PCs, electric tools, and electric bicycles. In recent years, secondary batteries are also used for power generation using natural energy such as wind power generation and solar power generation. This is used to supplement unstable output with a secondary battery and smooth the output, and a large-capacity secondary battery is used. In addition, it is known that large-capacity secondary batteries are mounted on vehicles such as hybrid cars, electric cars, and trains.

  Nickel metal hydride batteries and lithium ion batteries are widely used for such high-capacity secondary batteries mounted on such vehicles in terms of high output, high energy density, voltage stability, and the like.

  Examples of conventional nickel metal hydride batteries and lithium ion batteries include a wound secondary battery and a square secondary battery. In addition, a cylindrical secondary battery represented by a nickel metal hydride battery includes a positive electrode active material sheet containing a positive electrode active material (such as nickel hydroxide) and a negative electrode active material sheet containing a negative electrode active material (such as a hydrogen storage alloy). And an electrode body wound in a spiral shape through a plate-shaped separator that electrically insulates between both sheets and conducts ions through an electrolyte contained therein. And this electrode body is accommodated in the bottomed cylindrical battery container which has the bottom which opened upwards and serves as a negative electrode external terminal. The opening of the battery container is covered with a lid that also serves as a positive electrode external terminal, whereby the positive electrode external terminal constitutes a part of the battery container (for example, see Patent Document 1). Moreover, the positive electrode external terminal and the positive electrode active material sheet of the electrode body are each welded via conductive tabs, such as nickel (for example, refer patent document 2).

  In addition, in an electrical energy storage device housed in a housing in which an electrolyte is stored, an electrode body separated by a separator and wound so that a positive electrode protrudes at one end and a negative electrode protrudes at the other end, and a lower surface There is an electrical energy storage device having a contact area enlarging means and a positive electrode terminal and a negative electrode terminal respectively connected to the positive electrode and the negative electrode of the electrode body (see, for example, Patent Document 3).

  On the other hand, the applicant of the present application shifted both sheets in the axial direction through the separator so that the positive electrode active material sheet protrudes from one end of the electrode body in the axial direction and the negative electrode active material sheet protrudes from the other end. The separator is wound in a spiral shape, and the separator is interposed between the positive electrode active material sheet and the negative electrode active material sheet so as to cover the end opposite to the protruding direction of the negative electrode active material sheet. One end of the positive electrode active material sheet or the negative electrode active material sheet is sandwiched between the first separator having one end bent and the first separator, and the end opposite to the protruding direction of the positive electrode active material sheet is covered. Thus, a wound battery comprising a second separator whose other end is bent is invented (see, for example, Patent Document 4).

JP 2003-272593 A JP-A-4-137356 JP 2002-015765 A Japanese Patent No. 4298245

  However, the battery of Patent Document 1 or 2 has two welds in the path on the positive electrode side through which electricity flows. In this configuration, when the battery is discharged at a high output due to the electrical resistance of the welded portion, the voltage between both ends of the battery is lowered, and the battery performance cannot be sufficiently secured. In addition, since there are welds, the battery manufacturing time and manufacturing process increase, and the manufacturing cost increases.

  Moreover, in the electrical energy storage device of Patent Document 3, both ends of the positive electrode and the negative electrode are exposed to the outside in the axial direction, and effective prevention of a short circuit between the positive electrode terminal and the negative electrode and a short circuit between the negative electrode terminal and the positive electrode is performed. I can't. By the way, when a positive electrode, a negative electrode, and a separator (separation film) are overlapped to manufacture an electrode body, or when the positive electrode or the negative electrode expands and contracts due to charge / discharge, the positive electrode, the negative electrode, and the separator may be displaced. In the electric energy storage device of Patent Document 3, when the separator is displaced, the current collection becomes weak, and when the positive electrode and the negative electrode come into contact with each other, a short circuit occurs.

  Moreover, since the winding battery of patent document 4 is the structure by which the separator which covers these edge parts is piled up on the positive electrode and the negative electrode, it can prevent effectively the short circuit by the contact of the edge part of a positive electrode and a negative electrode. However, since this separator is divided into a first separator and a second separator that are superimposed on the positive electrode and the negative electrode, respectively, workability is poor when these are overlapped and wound. Moreover, there is a possibility that the positive electrode, the negative electrode, the first separator, or the second separator may be displaced. If the displacement occurs, the current collection may be weakened.

  The present invention has been made in view of the above problems, and by electrically connecting the positive electrode of the electrode body to the positive electrode current collector and the negative electrode to the negative electrode current collector by contact without welding. It is an object of the present invention to provide a secondary battery that can be manufactured very easily and that achieves high performance by reducing voltage drop and prevents the displacement of the positive electrode, negative electrode, and separator, and a method for manufacturing the same.

  In order to achieve the above object, a secondary battery according to the present invention includes a positive electrode current collector and a negative electrode current collector that are disposed to face each other, and between the positive electrode current collector and the negative electrode current collector. And an electrode body in which a positive electrode and a negative electrode are spirally wound via a separator, and the electrode body has the positive electrode at one end in the axial direction and the negative electrode at the other end. The positive electrode and the negative electrode are overlapped in a state of being shifted in the axial direction so as to protrude, and each of the separators is bent so as to cover an end opposite to the protruding direction of the negative electrode, and the positive electrode The end of the positive electrode is in contact with the positive electrode current collector and the end of the positive electrode current collector is in contact with the positive electrode current collector. And the negative electrode current collector are in contact with each other. .

  According to this configuration, since there is no welded portion between the positive electrode and the positive electrode current collector and between the negative electrode and the negative electrode current collector, a high-performance secondary battery is obtained with little voltage drop even at high output discharge. It is done. In addition, the separator of the present invention is configured to be bent so as to cover the end portions on the opposite side to the protruding direction of the positive electrode and the negative electrode. Therefore, even when the separator physically separates the positive electrode and the negative electrode and any of the protruding positive electrode and negative electrode is deformed by some external force or the like, the electrical insulation between the positive electrode and the negative electrode is maintained.

  Furthermore, since this separator can be configured by simply folding a sheet-like separator, the workability is very good when the electrode body is produced by sandwiching the positive electrode and the negative electrode between the separators, and the possibility of deviation is extremely low. Reduces weakening of current collection due to deviation.

  Further, the secondary battery according to the present invention includes a first separator portion, a second separator portion, and a third separator portion that sandwich the positive electrode between the second separator portion and the negative electrode. A first bent portion connecting the first separator portion and the second separator portion so as to cover an end opposite to the protruding direction, and a second bent portion covering the end opposite to the protruding direction of the positive electrode. A second bent portion connecting the separator portion and the third separator portion. According to this configuration, the second separator portion reliably insulates the positive electrode and the negative electrode, and the first separator portion and the second separator portion reliably insulate the overlapping portion of the positive electrode and the negative electrode during winding. To do.

  In the secondary battery according to the present invention, the length of the second separator portion is shorter than the length obtained by adding the first separator portion and the third separator portion in the axial direction of the electrode body. Here, “the length of the second separator portion is shorter than the total length of the first separator portion and the third separator portion” means that the first separator portion and the third separator portion at the time of winding. When the separator part overlaps, it means that the overlapping part can be surely made. For example, the first separator part and the third separator part may be configured to be longer than ½ of the second separator part, or the first separator part and the third separator part may be configured to have the same length as the second separator part. Good. Thus, the first separator portion and the third separator portion reliably prevent the positive electrode and the negative electrode from overlapping during winding and electrically insulate the positive electrode and the negative electrode.

  Moreover, the secondary battery which concerns on this invention may be provided with the slit from the edge part on the opposite side to the said 2nd bending part of the said 3rd separator part. According to this configuration, when the positive electrode, the negative electrode, and the separator are wound at the time of manufacturing the electrode body, the bending of the separator can be released by the slit, and the winding can be efficiently performed.

  In the secondary battery according to the present invention, the electrode body may have an insulating axis. According to this configuration, winding can be easily performed at the time of manufacturing the electrode body. Further, the shaft center may be solid or hollow, and the shaft center may be removed after winding. The shaft center is preferably insulative and resistant to the electrolyte.

  In the secondary battery according to the present invention, it is preferable that the electrode body is wound in a spiral shape so that the negative electrode is located outside the positive electrode via the separator. According to this configuration, the secondary battery is positive electrode regulated.

  Further, the secondary battery according to the present invention includes a plurality of sheets in which at least one of the positive electrode and the negative electrode is divided in a circumferential direction of the electrode body, and the positive electrode or the negative electrode sheet outside the electrode body. The thickness may be greater than the inner sheet thickness. According to this configuration, the electrode on the outer side of the electrode body becomes thick, the winding is fastened, and the form of the electrode body is stabilized.

  Further, in the secondary battery according to the present invention, the electrode body has the separator formed in a bellows shape in the radial direction of the electrode body, and a plurality of positive electrodes and a plurality of negative electrodes are sandwiched between the separators. The positive electrode and the plurality of negative electrodes may be spirally wound through the separator. According to this configuration, the number of times of wrinkles can be reduced.

  Further, in the secondary battery according to the present invention, the plurality of positive electrodes and the plurality of negative electrodes are overlapped in a state that is sequentially shifted in the circumferential direction so that end portions in the circumferential direction of the electrode body become shorter toward the outside. Also good. According to this configuration, when the electrode body is configured by stacking and winding a plurality of positive and negative electrodes and a bellows-shaped separator, the outer ends of the positive and negative electrodes are prevented from being flush with each other. Suppresses short circuit in

  Moreover, the secondary battery according to the present invention further includes a binding member in which the electrode body is wound around and bound to the outer peripheral portion thereof. According to this configuration, the binding member wraps around the outer periphery of the electrode body and restricts the form of the electrode body, thereby maintaining the wound state of the electrode body. Note that it is desirable to use an electrolyte-resistant material for the binding member.

  The secondary battery according to the present invention includes a plurality of the electrode bodies, and the plurality of electrode bodies are arranged in a container having two surfaces constituting the positive electrode current collector and the negative electrode current collector, The positive electrode current collector is in contact with the end of the positive electrode of each of the plurality of electrode bodies, and the negative electrode current collector is in contact with the end of the negative electrode of each of the plurality of electrode bodies. In the secondary battery according to the present invention, the plurality of electrode bodies may include electrode bodies having different diameters.

  According to this configuration, since the plurality of electrode bodies are electrically connected in parallel by being arranged in parallel in the container, the battery capacity can be increased. A plurality of electrode bodies having the same diameter may be arranged in the container, or electrode bodies having different diameters may be arranged. The plurality of electrode bodies may be a plurality of types of electrode bodies having different charge / discharge characteristics. In this way, by combining electrode bodies having different diameters or a plurality of electrode bodies having different charge / discharge characteristics, a secondary battery can be configured according to the purpose of use. For example, it is possible to provide a secondary battery that simultaneously satisfies an instantaneous large current and a large battery capacity that cannot be realized with one type of electrode body.

  Further, the method for manufacturing a secondary battery according to the present invention includes a method of bending the separator along the longitudinal direction so as to form a first separator part and a second separator part for sandwiching the positive electrode, and the second separator part. A first step of bending the separator along the longitudinal direction so as to form a third separator for sandwiching the negative electrode; and the first separator so that one end of the positive electrode protrudes from one end of the separator The positive electrode is disposed between the second separator portion and the second separator portion, and the one end portion of the negative electrode protrudes from the other end side of the separator. A second step of disposing a negative electrode, a third step of winding the superimposed positive electrode, negative electrode, and separator into a spiral to form an electrode body; and one end of the electrode body in the axial direction And the positive electrode current collector, the positive electrode current collector is brought into contact with the end of the positive electrode protruding from between the first separator part and the second separator part, and the electrode body Abutting the other end portion in the axial direction with the negative electrode current collector makes the negative electrode current collector contact with the end portion of the negative electrode protruding from between the second separator portion and the third separator portion. And a fourth step.

  According to this configuration, since the positive electrode and the negative electrode are shifted in opposite directions with respect to the separator and wound in a spiral shape, each end of the electrode body formed thereby has a different polarity. Can protrude. That is, the positive electrode projects from one end of the electrode body, and the negative electrode projects from the other end. In addition, since the positive electrode protruding from the electrode body is in contact with the positive electrode current collector and the negative electrode protruding from the electrode body is in contact with and electrically connected to the negative electrode current collector, the conventional secondary battery is used. This eliminates the need for a welding process. As a result, the secondary battery can be manufactured very easily, the manufacturing period can be shortened, and the cost can be further reduced.

  Further, the first step includes a step of bending the separator so as to cover the ends of the positive electrode and the negative electrode opposite to the protruding direction, respectively, so that the positive electrode and the negative electrode are physically separated by the electrically insulating separator. Separated to ensure electrical insulation between the positive and negative electrodes. Here, the separator is bent by, for example, mountain-folding and valley-folding so that the cross section is substantially N-shaped, and the positive electrode and the negative electrode are sandwiched between the bent separators. In this separator, one sheet is bent, and the negative electrode is securely clamped between the first separator part and the second separator part, and the positive electrode is securely clamped between the second separator part and the third separator part. Deviation is less likely to occur during body manufacturing. Therefore, the manufacture of the electrode body is further facilitated, and in addition, the secondary battery manufactured thereby is less likely to be displaced during its operation, so that a high performance secondary battery can be obtained without weakening current collection.

  As described above, the secondary battery according to the present invention reduces the voltage drop by electrically connecting the positive electrode of the electrode body to the positive electrode current collector and the negative electrode to the negative electrode current collector without welding. It can be reduced to achieve higher performance. Further, the displacement of the positive electrode, the negative electrode, and the separator is suppressed to prevent a short circuit and the current collection is prevented from being weakened.

FIG. 1 is a partially broken perspective view of a secondary battery according to an embodiment of the present invention. FIG. 2 is a partially cutaway perspective view of the electrode body of FIG. FIG. 3 is a cross-sectional view of the electrode body of FIG. 4 (a) to 4 (d) are explanatory views showing manufacturing steps of the electrode body of FIG. FIGS. 5A to 5C are diagrams showing a modification of the electrode body of FIG. FIGS. 6A to 6C are diagrams showing a modification of the electrode body of FIG. FIG. 7A is a cross-sectional view taken along the line AA in FIG. FIG.7 (b) is a figure which shows the modification of the secondary battery which arranged the several electrode body from which a diameter differs in the battery container.

  Hereinafter, although the embodiment concerning the present invention is described based on a drawing, the present invention is not limited to the following embodiment.

[1. Secondary battery structure]
(1-1. Structure of entire battery and battery container)
As shown in FIG. 1, the secondary battery 1 of the present embodiment is configured by a plurality of substantially cylindrical electrode bodies 2 being housed in a rectangular battery container 3 together with an electrolytic solution. The battery container 3 includes an insulating rectangular frame-shaped member 33, and a negative electrode current collector 31 and a positive electrode current collector 32 that are arranged facing the X direction so as to cover two openings of the frame-shaped member 33. , The inside is sealed. The negative electrode current collector 31 and the positive electrode current collector 32 have flat plate-like main body portions 31a and 32a, and side wall portions 31b and 32b that project from the peripheral edge portion in the X direction. In addition, the inner surface where the negative electrode current collector 31 and the positive electrode current collector 32 face each other serves as a negative electrode current collecting surface and a positive electrode current collecting surface, and the surfaces exposed to the outside serve as a negative electrode terminal surface and a positive electrode terminal surface.

  In this embodiment, a modified polyphenylene ether (PPE) resin is used as an insulating material for forming the frame-shaped member 33, but various materials can be selected from the viewpoint of mechanical strength, heat resistance, and electrolytic solution resistance. . In addition, as a material for forming the negative electrode current collector 31 and the positive electrode current collector 32, a nickel-plated steel plate, which is a conductive material, is used. In consideration of electrochemical characteristics, mechanical strength, corrosion resistance, and the like. And can be selected as appropriate.

(1-2. Structure of electrode body)
As shown in FIG. 2, the electrode body 2 includes a sheet-like negative electrode 21, a sheet-like positive electrode 22, a sheet-like separator 23, and an insulating and substantially cylindrical shaft center 24. The separator 23 is composed of a single sheet, and is folded at two locations, a valley fold and a mountain fold, along the longitudinal direction to form a first separator portion 23a, a second separator portion 23b, and a third separator portion 23c. . Further, a bent portion between the first separator portion 23a and the second separator portion 23b becomes the first bent portion 23d, and a bent portion between the second separator portion 23b and the third separator portion 23c becomes the second bent portion 23e.

  The negative electrode 21 is sandwiched between the first separator portion 23a and the second separator portion 23b, the positive electrode 22 is sandwiched between the second separator portion 23b and the third separator portion 23c, and the negative electrode 21 is on the outside. Thus, the electrode body 2 is formed by winding these in a spiral shape (see FIG. 3). In this manner, the separator 23 is interposed between the negative electrode 21 and the positive electrode 22 to electrically insulate between the negative electrode 21 and the positive electrode 22 and to conduct ions through the electrolyte contained therein. In addition, although the electrode body 2 of this embodiment has distribute | arranged the negative electrode 21 on the outer side, it is good also as a structure which distribute | arranges the positive electrode 22 on the outer side.

  Further, one end portion 21a of the negative electrode 21 protrudes from one end portion (upper end portion in FIG. 2) in the X direction which is the axial direction of the electrode body 2, and the other end portion (lower end portion in FIG. 2). The one end part 22a of the positive electrode 22 protrudes. The other end 21b opposite to the protruding direction of the negative electrode 21 is covered with a first bent portion 23d, and the other end 22b opposite to the protruding direction of the positive electrode 22 is covered with a second bent portion 23e. Then, in a state where the electrode body 2 is housed in the battery container 3, one end portion 21 a of the negative electrode 21 is in contact with the negative electrode current collector 31, and one end portion 21 a of the positive electrode 21 is in contact with the positive electrode current collector 32. Connected.

  With the above configuration, contact between the negative electrode 21 and the positive electrode 22 can be prevented by the separator 23, and a short circuit can be prevented.

(1-3. Material of electrode body)
Next, each material which comprises the electrode body 2 of this embodiment is demonstrated taking a nickel hydride battery as an example. In addition, the material shown below is suitably changed according to the kind of secondary battery 1. FIG.

  The negative electrode 21 is formed by applying a hydrogen storage alloy powder serving as a negative electrode active material to a plate-like body such as conductive punching metal, drying, and rolling to a predetermined thickness. The positive electrode 22 is formed by applying nickel hydroxide as a positive electrode active material to a plate-like body such as conductive foamed nickel, drying, and rolling to a predetermined thickness.

  The separator 23 is made of a hydrophilic nonwoven fabric of polypropylene, polyethylene or polyamide which is an electrical insulating material. Thereby, the separator 23 can hold | maintain many electrolyte solutions. As a result, ion conduction between the negative electrode 21 and the positive electrode 22 is facilitated. Alkaline potassium hydroxide is used as the electrolytic solution.

  The battery reaction in this configuration will be briefly described. In the discharged state, hydrogen occluded in the negative electrode 21 becomes hydrogen ions and reaches the positive electrode 22 through the electrolyte contained in the separator 23. Therefore, it reacts with nickel oxyhydroxide to become nickel hydroxide. In the charged state, the reverse reaction occurs.

[2. Electrode body manufacturing method]
Next, a method for manufacturing the electrode body 2 will be described.
(2-1. Step 1)
As shown in FIG. 4A, a single rectangular sheet-like separator 23 is valley-folded along the longitudinal direction to form a first separator portion 23a. Similarly, the separator 23 is mountain-folded along the longitudinal direction to form the third separator portion 23c. At the same time, a second separator portion 23b that connects the first separator portion 23a and the third separator portion 23c is formed. Further, a bent portion between the first separator portion 23a and the second separator portion 23b is formed as a first bent portion 23d, and a bent portion between the second separator portion 23b and the third separator portion 23c is formed as a second bent portion 23e. .

(2-2. Step 2)
Next, as shown in FIG. 4B, the other end portion 21b of the negative electrode 21 (the lower end portion of FIG. 4B) is aligned with the first bent portion 23d, and the negative electrode 21 is aligned with the first separator portion 23a. It is sandwiched between the two separator parts 23b. Thereby, the one end part 21a (upper end part of FIG.4 (b)) of the negative electrode 21 protrudes above the 1st separator part 23a and the 2nd separator part 23b. On the other hand, the other end portion 22b of the positive electrode 22 (upper end portion in FIG. 4B) is aligned with the second bent portion 23e, and the positive electrode 22 is sandwiched between the second separator portion 23b and the third separator portion 23c. Thereby, the one end part 22a (lower end part of FIG.4 (b)) of the positive electrode 22 protrudes below the 2nd separator part 23b and the 3rd separator part 23c.

(2-3. Step 3)
Next, as shown in FIG. 4C, a stack of the negative electrode 21, the positive electrode 22, and the separator 23 is spirally wound around the axis 24 along the longitudinal direction thereof. In addition, it winds so that the negative electrode 21 may come to the outer side of the electrode body 2 so that it may become a positive electrode control battery. Thereby, the substantially cylindrical electrode body 2 is formed, and different polarities are formed at each end thereof. That is, the negative electrode 21 projects from one end of the electrode body 2 in the axial direction, and the positive electrode 22 projects from the other end.

(2-4. Step 4)
Next, as shown in FIG. 4D, in consideration of the form stability of the electrode body 2, a belt-like binding member 25 is wound around the outer periphery of the electrode body 2, and both ends of the binding member 25 are heat-sealed. Glue with. An annular binding member may be used. Moreover, in this embodiment, the binding member 25 is wound around one place as an example, but the number may be appropriately set according to the constituent material of the electrode body 2 and the like. Further, the bundling member 25 is also preferably resistant to an electrolyte solution (alkali resistance in the present embodiment) like the separator 23. Therefore, the bundling member 25 of the present embodiment is made of, for example, an electrically insulating material such as polypropylene, polyethylene, or polyamide-based hydrophilic nonwoven fabric. Note that the step of winding the binding member 25 around the electrode body 2 may be omitted when the shape of the wound electrode body 2 is stable.

  The electrode body 2 is completed by the steps 1 to 4 described above. The plurality of electrode bodies 2 manufactured in this way are arranged and stored in parallel in the battery container 3, the battery container 3 is filled with an electrolytic solution, and the battery container 3 is sealed to complete the secondary battery 1. (See FIG. 1). Further, when the electrode body 2 is housed in the battery container 3, the end portions in the X direction of the plurality of electrode bodies 2 are brought into contact with the negative electrode current collector 31 and the positive electrode current collector 32, respectively. Thereby, the electrode bodies 2 are electrically connected in parallel.

  As described above, there is no welding process in manufacturing the electrode body 2 of the present embodiment. Therefore, its manufacture is much easier than before. As a result, the manufacturing time can be shortened and the manufacturing cost can be reduced. In addition, the manufacturing process of said electrode body 2 is an example, and is not limited to this.

[3. Modified example]
(3-1. Modification 1)
Next, a modified example of the electrode body 2 will be described.
In addition, the same code | symbol is attached | subjected about the same structure.
As illustrated in FIG. 5A, Modification 1 is a modification of the separator 23. The separator 123 is a separator provided with a slit 23f. The separator 123 is provided with two slits 23f cut in the longitudinal direction from the end of the third separator portion 23c opposite to the second bent portion 23e. Thereby, when winding the negative electrode 21, the positive electrode 22, and the separator 123, the bending of the separator 123 can be suppressed and it can wind efficiently.

(3-2. Modification 2)
As illustrated in FIG. 5B, Modification 2 is a modification of the separator 23. In the separator 23, the first separator portion 23a, the second separator portion 23b, and the third separator portion 23c have substantially the same length in the X direction, whereas the modified separator 223 includes the first separator portion 23a. The length of the X direction of 223a and the 3rd separator part 223c is slightly longer than 1/2 of the length of the 2nd separator part 223b. Thereby, when the 1st separator part 223a and the 3rd separator part 223c are piled up, an overlapping part is made, and when the negative electrode 21, the positive electrode 22, and the separator 223 are wound, the contact between the negative electrode 21 and the positive electrode 22 is made. In addition, the overlapping portion can be made smaller than the separator 23 described above.

(3-3. Modification 3)
As shown in FIG. 5C, Modification 3 is a modification of the negative electrode 21 and the positive electrode 22. The negative electrode 121 includes a negative electrode 121A and a negative electrode 121B having different sheet thicknesses. The positive electrode 122 includes a positive electrode 122A and a positive electrode 122B having different sheet thicknesses. Note that the negative electrode 121B and the positive electrode 122B are thicker than the negative electrode 121A and the positive electrode 122A. The negative electrode 121A and the negative electrode 121B are sequentially sandwiched between the first separator portion 23a and the second separator portion 23b of the separator 23 in the longitudinal direction Y. Similarly, the positive electrode 122A and the positive electrode 122B are connected to the second separator portion 23b and the third separator portion 23b. The sheet is sandwiched in order in the longitudinal direction Y with respect to the separator 23c. Then, these are wound so that the negative electrode 121A and the positive electrode 122A having a thick sheet come outside the electrode body 2. Thus, the negative electrode 121 is divided into the negative electrode 121A and the negative electrode 121B in the circumferential direction C of the electrode body 2, and the positive electrode 122 is divided into the positive electrode 122A and the positive electrode 122B in the circumferential direction C of the electrode body 2, The negative electrode 121A and the positive electrode 122A having a large sheet thickness are positioned outside the electrode body 2, and the form of the electrode body 2 is stabilized.

(3-4. Modification 4)
As shown in FIGS. 6A to 6C, Modification 4 is a modification in which a plurality of negative electrodes 21 and positive electrodes 22 are provided, and a separator 23 is formed in a bellows shape. The separator 323 is a separator formed by bending a single sheet a plurality of times so that the cross section is formed in a bellows shape in the radial direction R of the electrode body 2. Then, the plurality of negative electrodes 21 and positive electrodes 22 are alternately sandwiched between the bellows-shaped separators 323, and these are wound. As a result, the electrode body 120 can be formed with a smaller number of windings than the electrode body 2 described above.

  Further, in the electrode body 120 of Modification 4, when the negative electrode 21 and the positive electrode 22 are sandwiched between the separators 323, the ends of the negative electrode 21 and the positive electrode 22 in the longitudinal direction Y are sequentially shifted. Thereby, since the edge part of the negative electrode 21 and the positive electrode 22 in the outer periphery of the electrode body 120 shift | displaces in order, the short circuit in an edge part can be suppressed rather than the case where an edge part is flush.

(3-5. Modification 5)
7A is a cross-sectional view taken along the line AA of the secondary battery 1 of FIG. 1, and FIG. 7B is a cross-sectional view of the secondary battery 110 in which the arrangement of the electrode bodies housed in the battery container 3 is changed. is there. Modification 5 is a modification in which electrode bodies having different diameters are arranged and stored in the battery container 3, and the secondary battery 110 has a large diameter in the battery container 3 as shown in FIG. 7B. An electrode body 220A, an electrode body 220B having a smaller diameter, and an electrode body 220C having a smaller diameter are disposed around the electrode body 220A. Thereby, the battery 110 can reduce the number of the electrode bodies accommodated in the battery container 3 rather than the secondary battery 1 in which a plurality of the electrode bodies 2 having the same diameter are arranged. Risk associated with the entire battery represented by the risk of short circuit and the like × the number of electrode bodies can be reduced.

(3-6. Modification 6)
Moreover, although not shown in figure, it is good also considering the several electrode body accommodated in the battery container 3 as a combination of the electrode body which has a different charging / discharging characteristic. As an example, a combination of an electrode body having a characteristic of charging / discharging a large current instantaneously and an electrode body having a characteristic of charging / discharging for a long time (large electric capacity) while allowing only a small current to flow. As a result, the secondary battery becomes a secondary battery that can charge and discharge a large current instantaneously and can be charged and discharged for a long time. For example, a momentary large current is required when accelerating, and the travel distance is increased. The present invention is applied to an electric vehicle or an electric bicycle that requires a large electric capacity. Note that the combination of electrode bodies having different charge / discharge characteristics may be set as appropriate according to the application of the secondary battery.

(3-7. Modification 7)
Although not shown, a substantially cylindrical secondary battery in which one electrode body 2 is housed in a substantially cylindrical battery container may be used.

[4. Effects of this embodiment]
As described above, in the secondary battery 1 of the present embodiment, the negative electrode 21 of the electrode body 2 is electrically connected to the negative electrode current collector 31 and the positive electrode 22 to the positive electrode current collector 32 without being welded to each other by contact. By doing so, even in the case of high output discharge, it is possible to reduce the voltage drop and improve the performance. The separator 23 is formed by bending a single sheet to form a first separator portion 23a, a second separator portion 23b, and a third separator portion 23c, and a negative electrode between the first separator portion 23a and the second separator portion 23b. 21 has a structure in which the positive electrode 22 is sandwiched between the second separator portion 23b and the third separator portion 23c, so that the negative electrode 21, the positive electrode 22, and the separator 23 are displaced during the manufacturing process of the electrode body 2 and the operation of the secondary battery 1. Can be prevented. Therefore, a short circuit due to these deviations is prevented and current collection is prevented from being weakened.

  Moreover, the manufacturing method of the secondary battery 1 of the present embodiment is such that the connection between the negative electrode 21 and the negative electrode current collector 31 and the connection between the positive electrode 22 and the positive electrode current collector 32 are not contacted by welding but are made by contact. In addition, since the welding process is unnecessary, the secondary battery 1 can be manufactured very easily. In addition, the separator 23 bends one sheet in two places, sandwiches the negative electrode 21 and the positive electrode 22 between them, and winds them to manufacture the electrode body 2, so that the negative electrode 21, the positive electrode 22, and the separator 23 during winding are Hard to slip. Therefore, the manufacture of the electrode body 2 is facilitated, and the contact between the negative electrode 21 and the positive electrode 22 is reliably prevented.

[5. Other Embodiments]
As described above, the preferred embodiments of the present invention have been described with reference to the drawings, but various additions, modifications, or deletions can be made without departing from the spirit of the present invention. For example, in the present embodiment, the case where the secondary battery 1 is a nickel metal hydride battery has been described. However, the present invention may be applied to a nickel cadmium battery, a lithium battery, a lithium ion battery, a lead storage battery, a manganese battery, an electric double layer capacitor, or the like. . In addition to nickel foam and punching metal, an electrode using a nickel-plated steel plate or carbon fiber as a current collecting substrate may be used as the electrode. In addition to the hollow shaft center, the shaft center 24 of the electrode body 2 may be a solid shaft center or no shaft center. Further, the cross-sectional shape of the electrode body 2 may be applied to an elliptical shape, an oval shape, a polygonal shape, or the like other than the substantially perfect circle shape. Therefore, such a thing is also included in the scope of the present invention.

  The secondary battery according to the present invention can be suitably used as a secondary battery for electric railway vehicles, other vehicles, heavy machinery, microgrids, natural energy power generation assistance, system power smoothing, and the like.

DESCRIPTION OF SYMBOLS 1 Secondary battery 2 Electrode body 21 Negative electrode 21a One end part 21b Other end part 22 Positive electrode 22a One end part 22b Other end part 23 Separator 23a First separator part 23b Second separator part 23c Third separator part 23d First bent part 23e Second Bending part 23f Slit 24 Axis 25 Binding member 3 Battery container 31 Negative electrode current collector 32 Positive electrode current collector 33 Frame member 110 Secondary battery 120 Electrode body 121 Negative electrode 122 Positive electrode 123, 223, 323 Separator

Claims (13)

A positive electrode current collector and a negative electrode current collector disposed to face each other;
An electrode body disposed between the positive electrode current collector and the negative electrode current collector, wherein the positive electrode and the negative electrode are spirally wound via a separator,
The electrode body is overlapped in a state where the positive electrode and the negative electrode are shifted in the axial direction so that the positive electrode protrudes at one end in the axial direction and the negative electrode protrudes at the other end,
Each of the separators is bent so as to cover an end opposite to the protruding direction of the negative electrode, and is bent so as to cover an end opposite to the protruding direction of the positive electrode,
In the positive electrode, the end portion on the protruding direction side contacts the positive electrode current collector, and in the negative electrode, the end portion on the protruding direction side contacts the negative electrode current collector,
Secondary battery. The separator is
A first separator part and a second separator part sandwiching the negative electrode;
The second separator part and the third separator part sandwiching the positive electrode;
A first bent portion connecting the first separator portion and the second separator portion so as to cover an end portion on the opposite side to the protruding direction of the negative electrode;
A second bent portion connecting the second separator portion and the third separator portion so as to cover the end portion on the opposite side to the protruding direction of the positive electrode,
The secondary battery according to claim 1. In the axial direction of the electrode body, the length of the second separator portion is shorter than the total length of the first separator portion and the third separator portion,
The secondary battery according to claim 2. From the end of the third separator portion opposite to the second bent portion, a slit is provided,
The secondary battery according to claim 2 or 3. The electrode body has an insulating axis.
The secondary battery of any one of Claims 1-4. The electrode body was wound in a spiral shape so that the negative electrode was outside the positive electrode via the separator,
The secondary battery of any one of Claims 1-5. At least one of the positive electrode and the negative electrode is composed of a plurality of sheets divided in the circumferential direction of the electrode body,
The sheet thickness of the outer positive electrode or the negative electrode in the electrode body is thicker than the inner sheet thickness,
The secondary battery of any one of Claims 1-6. The electrode body is
The separator is formed in a bellows shape in the radial direction of the electrode body,
A plurality of positive electrodes and a plurality of negative electrodes are sandwiched between the separators, and the plurality of positive electrodes and the plurality of negative electrodes are spirally wound through the separators,
The secondary battery of any one of Claims 1-7. The plurality of positive electrodes and the plurality of negative electrodes were overlapped in a state shifted in order in the circumferential direction so that the end in the circumferential direction of the electrode body was shorter toward the outside,
The secondary battery according to claim 8. The electrode body further includes a binding member that is wound around and bound to the outer peripheral portion thereof.
The secondary battery of any one of Claims 1-9. A plurality of the electrode bodies;
A plurality of electrode bodies are arranged in a container having two surfaces constituting the positive electrode current collector and the negative electrode current collector,
The positive electrode current collector is in contact with an end of the positive electrode of each of the plurality of electrode bodies, and the negative electrode current collector is in contact with an end of the negative electrode of each of the plurality of electrode bodies;
The secondary battery of any one of Claims 1-10. The plurality of electrode bodies include electrode bodies having different diameters.
The secondary battery according to claim 11. The separator is bent along the longitudinal direction so as to form a first separator portion and a second separator portion for sandwiching the positive electrode, and a third separator portion is formed for sandwiching the negative electrode with the second separator portion. A first step of bending the separator along the longitudinal direction;
The positive electrode is arranged between the first separator portion and the second separator portion so that one end portion of the positive electrode protrudes from one end side of the separator, and one end portion of the negative electrode from the other end side of the separator A second step of disposing the negative electrode between the second separator part and the third separator part, so as to protrude,
A third step of winding the superimposed positive electrode, negative electrode, and separator into a spiral to form an electrode body;
The end portion of the positive electrode protruding from between the first separator portion and the second separator portion by bringing the one end portion in the axial direction of the electrode body into contact with the positive electrode current collector The negative electrode current collector is protruded from between the second separator portion and the third separator portion by contacting the other end portion of the electrode body in the axial direction with the negative electrode current collector. A fourth step of contacting the end of the negative electrode,
A method for manufacturing a secondary battery.

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