JP3551365B2 - Flat shape wound electrode battery - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a battery having a flat-shaped wound electrode body in which a sheet-shaped positive electrode plate and a negative electrode plate are wound in a flat shape with a separator interposed therebetween, and in particular, a flat-shaped wound electrode suitable for application to electric vehicles and the like. The present invention relates to a type electrode battery.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with increasing interest in environmental issues, electric vehicles have attracted public attention. The battery for the electric vehicle is required to have a high output supply for driving the vehicle, that is, a capability of discharging a large current.
[0003]
Further, in a battery used as a power source of a conventional portable device, the performance of the battery is improved by using a wound electrode body in which a sheet-shaped positive electrode plate and a negative electrode plate are wound through a separator. ing. The spirally wound electrode body may be a spirally wound cylindrically wound electrode body, or a flatly wound spirally wound electrode body in which the spirally cylindrical shape is flattened in a direction orthogonal to a winding axis. There is.
[0004]
A battery having such a wound electrode body generally has a structure in which the wound electrode body is sealed together with an electrolytic solution inside a case, and the power from the wound electrode body is Extraction is performed by connecting electrode terminals to the positive electrode plate and the negative electrode plate. As for the extraction of the electric power, for example, a tab is formed on each electrode plate, and the tab is joined to the electrode terminal to extract the electric current.
[0005]
A battery for extracting electric power from an electrode body using such a tab has been difficult to apply to an electric vehicle. That is, a battery for an electric vehicle is required to have a large current. However, in such a battery, there is a risk of overheating and burning at the junction of the tab due to the flow of the large current.
[0006]
2. Description of the Related Art Conventionally, a battery having a structure for extracting a large current has been disclosed in, for example, JP-A-2000-40501. This battery has a flat wound electrode body formed by winding a strip-shaped positive electrode plate and a negative electrode plate each having an electrode active material through a strip-shaped separator, and a flat-shaped wound electrode body. It has a positive electrode terminal and a negative electrode terminal whose shafts are connected to the positive electrode plate and the negative electrode plate of the round electrode body. The positive electrode plate and the negative electrode plate have respective edges protruding from the separator in directions opposite to each other along the axial direction of the flat-shaped wound electrode body, and have no electrode active material applied thereto. At least a part is compressed and laminated to form each protruding end portion which is joined to each other in the thickness direction of the flat-shaped wound electrode body and is thinner than the thickness of the flat-shaped wound electrode body. In addition, the positive electrode terminal and the negative electrode terminal are joined to the protruding ends with their shafts extending in a direction intersecting the direction in which the protruding ends protrude.
[0007]
However, since the outermost surfaces of the respective shaft portions of the positive electrode terminal and the negative electrode terminal exist in the thickness direction of the flat wound electrode body to a range exceeding the thickness of the flat wound electrode body, the battery physique Had the drawback of becoming larger.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above situation, and an object of the present invention is to provide a flat wound electrode battery that can be downsized.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have to put the connection part of the shaft of the positive electrode plate and the shaft part of the negative electrode plate within the thickness of the electrode body at each protruding end of the flat wound electrode body. It was found that the above problem could be solved.
[0010]
That is, the flat-shaped wound electrode battery of the present invention has a flat-shaped wound configuration in which a strip-shaped positive electrode plate and a negative electrode plate each having an electrode active material layer on both surfaces are formed in a rolled flat shape with a strip-shaped separator interposed therebetween. A positive electrode terminal and a negative electrode terminal each having a shaft portion connected to the positive electrode plate and the negative electrode plate of the flat wound electrode body, wherein the positive electrode plate and the negative electrode plate have a flat wound electrode. Each edge portion not coated with the electrode active material protruding from the separator in the opposite direction along the body axial direction, and an electrode portion coated with the electrode active material in contact with the separator, and each side has At least a part of the flat wound electrode body is joined to each other in the thickness direction of the flat wound electrode body in a state where the edges are stacked, and each protruding end portion thinner than the thickness of the stacked flat wound electrode body of the electrode portion is formed. , Positive terminal and negative terminal The flat wound electrode body is integrally joined on the lamination surface of each protruding end of the flat wound electrode body in a state of extending in a direction intersecting the protruding direction, and the axial center portion of the flat wound electrode body is extended. The radial distance from the contact surface with the protruding end of each shaft portion and the outermost surface of the shaft portion facing away from the shaft portion of the electrode portion of the flat wound electrode body to the outer peripheral surface of the electrode portion Is shorter than the radial distance.
[0011]
The flat wound electrode battery according to the present invention has a positive electrode terminal and a negative electrode terminal on a compressed surface side of each edge in a state in which a shaft portion extends in a direction in which each protruding end projects, It is joined to the lamination surface of each protruding end portion which is thinner than the thickness of the flat wound electrode body, so that the outermost surface of each shaft portion is the outermost surface of the flat wound electrode body. Since the setting is made so as not to exceed, the connection portion of the shaft portion of the electrode falls within the range of the thickness of the electrode body in the battery of the present invention, so that it is possible to avoid an increase in the size of the battery. .
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The flat wound electrode battery of the present invention has a flat wound electrode body, and a positive electrode terminal and a negative electrode terminal.
[0013]
The flat wound electrode body is an electrode body in which a strip-shaped positive electrode plate and a negative electrode plate each having an electrode active material layer on both surfaces are formed into a wound flat shape with a strip-shaped separator interposed therebetween. Here, this flat-shaped wound electrode body is an electrode body that is wound in an electrode plate including a positive electrode plate, a negative electrode plate, and a separator, and that is held in a flat shape that spreads in a radial direction of a winding axis. Show. In other words, the flat wound electrode body is an electrode body in which a positive electrode plate and a negative electrode plate are wound in a flat shape with a separator interposed therebetween, and the positive electrode plate and the negative electrode plate are wound with a separator interposed therebetween. After that, the electrode body may be deformed into a flat shape.
[0014]
Further, as the positive electrode plate, the negative electrode plate and the separator, those used in a normal wound electrode battery can be used. For example, examples of the positive electrode plate and the negative electrode plate include an electrode plate in which an electrode active material layer is formed on both surfaces of a current collector made of a conductive metal foil such as aluminum or copper. Examples of the separator include a sheet-like member made of polyethylene or polypropylene.
[0015]
The positive electrode terminal and the negative electrode terminal are members having a shaft connected to the positive electrode plate and the negative electrode plate of the flat wound electrode body. The positive electrode terminal and the negative electrode terminal take out electric power generated in each electrode plate by being connected to the positive electrode plate and the negative electrode plate at a shaft portion.
[0016]
The positive electrode terminal and the negative electrode terminal are preferably made of a rod-shaped member having a shaft. That is, since the positive electrode terminal and the negative electrode terminal are made of a rod-shaped member, the positive electrode terminal and the negative electrode terminal have rigidity, and when assembled into a battery, hold the flat wound electrode body in the battery container. Can be.
[0017]
Each of the positive electrode plate and the negative electrode plate has an edge where the electrode active material protruding from the separator in the opposite direction along the axial direction of the flat-shaped wound electrode body is not coated, and the electrode active material in contact with the separator is A flat-shaped wound type having at least a part thereof joined in a thickness direction of the flat-shaped wound electrode body in a state in which each edge portion is laminated, and a laminated electrode portion. Forming each protruding end portion thinner than the thickness of the electrode body, the positive electrode terminal and the negative electrode terminal of the flat wound electrode body with the shaft portion extending in a direction intersecting the direction in which each protruding end portion protrudes. Each of the protruding ends is integrally joined on the lamination surface, and at the end of the shaft portion facing the contact surface with the protruding end portion of each shaft portion from the shaft center portion of the flat wound electrode body. radial distance to the outer surface, the outer electrode portion from the winding axis of the electrode portion of the flat-shaped wound electrode body It is formed so as shorter than the radial distance to the surface.
[0018]
That is, the flat-shaped wound electrode body has a protruding end portion in which the edge portions on which the electrode active material is not applied are stacked and compressed. The thickness of the protruding end is formed smaller than the thickness of the laminated portion of the electrode portion. Therefore, there is a difference in thickness between the protruding end portion and the electrode portion. In the flat wound electrode battery according to the present invention, since the shafts of the positive electrode terminal and the negative electrode terminal are accommodated in the space created by the difference in thickness, the physical size can be reduced.
[0019]
Moreover, the flat-shaped wound electrode battery of the present invention has each protruding end portion, so that the distance of current flowing inside the positive electrode plate and the negative electrode plate is reduced. That is, since the protruding end portion itself is bonded to the electrode terminal, in the form having the conventional tab, the power obtained in the active material layer between the tabs of the electrode plate has a longer distance to the tab. Had become. Further, the length of the tab itself is increased by bending the tab itself, so that the current flowing distance is increased. For this reason, by connecting the positive electrode terminal or the negative electrode terminal to the protruding end, the distance of the current flowing from the electrode plate to the electrode terminal is reduced. When the current flowing distance is reduced, the influence of the internal resistance on the electrode plate and the electrode terminal is reduced, and the power efficiency is improved. Furthermore, since the electrode terminals are directly joined to the respective protruding ends, the connection resistance at the respective connection portions is also reduced. As a result, a wound electrode battery that can withstand a large current can be formed.
[0020]
Furthermore, since the positive electrode terminal and the negative electrode terminal are integrally joined to each protruding end portion at the shaft portion, the strength of the joint is increased. In other words, at the time of joining using the tab, it was not possible to impart strength to hold the electrode body to the tab itself by giving the tab flexibility, so members such as a core body were necessary, but it was directly joined. Therefore, these members for holding the wound electrode body are not required, and the cost of the battery can be reduced. Furthermore, since the shaft portions of the positive electrode terminal and the negative electrode terminal extend in a direction intersecting with the protruding direction of each protruding end portion, the holding strength of the flat wound electrode body in the axial direction is increased.
[0021]
The positive electrode terminal and the negative electrode terminal have other ends protruding from a direction intersecting the winding axis of the flat wound electrode body, and the other ends of the positive electrode terminal and the negative electrode terminal protrude in the same direction. Is preferred. That is, since the electrode terminal has the other end, the other end of the positive electrode terminal and the other end of the negative electrode terminal protrude from a direction intersecting with the axial direction of the spirally wound electrode body. Is improved. Specifically, the positive electrode and the negative electrode of the battery can be arranged in the same direction, and the workability when configuring the assembled battery is improved.
[0022]
It is preferable that the positive electrode terminal and the negative electrode terminal be joined to each protruding end in a state of extending in a direction parallel to a direction in which the flat shape of the flat wound electrode body spreads. That is, by providing the positive electrode terminal and the negative electrode terminal in a direction parallel to the direction in which the flat shape spreads, the thickness of the battery can be reduced.
[0023]
It is preferable that the respective protruding ends are integrally joined in a state where the stacked side edges are compressed in the thickness direction. Being integrally joined in the thickness direction means not only joining in the radial direction of the wound electrode body but also opposing in the thickness direction of the flat wound electrode body on the innermost peripheral surface of the electrode plate. This shows a state where the parts are joined. By compressing each protruding end portion, the thickness of the protruding end portion is made thinner than the central portion in the axial direction of the flat wound electrode body, that is, the thickness of the portion provided with the electrode active material layer. The space created by the difference in thickness can be used as a storage space for storing the respective shaft portions of the positive electrode terminal and the negative electrode terminal. By having the storage space for the shaft portion, the thickness of the battery of the present invention can be reduced, and the volumetric efficiency of the battery increases.
[0024]
At this time, it is preferable that each protruding end is compressed near the center in the thickness direction of the flat wound electrode body laminated radially inward from the outermost peripheral surface of the electrode plate. In other words, by compressing near the center in the thickness direction, the length of the edge protruding from the separator can be minimized. As a result, not only the cost required for the electrode plate can be suppressed from increasing, but also the moving distance of the charges moving in the electrode plate decreases, so that the increase in the internal resistance can be suppressed and the volume efficiency of the battery can be improved.
[0025]
The positive electrode terminal and the negative electrode terminal are preferably made of the same material as the current collector of the positive electrode plate or the negative electrode plate to which they are connected. Since the positive electrode terminal and the negative electrode terminal are formed of the same material as the current collector, the electrode terminals can be easily joined.
[0026]
It is preferable that the positive terminal and the negative terminal are connected to each protruding end by welding. That is, by joining the positive terminal and the negative terminal to the respective protruding ends by welding, the joining between the electrode terminals and the protruding ends can be reliably and easily performed. For this reason, the connection resistance at the junction between the electrode terminal and the protruding end is suppressed, and the internal resistance of the battery is reduced, so that heat generation is suppressed, so that it is possible to withstand a much larger current. . Examples of the method for joining the electrode terminal and the protruding end include electric welding such as spot welding and seam welding, and welding methods such as ultrasonic welding.
[0027]
It is preferable that welding between the positive electrode terminal and the negative electrode terminal and each protruding end is performed at one or more locations. By providing a plurality of welding locations, the joining between the positive electrode terminal and the negative electrode terminal and each protruding end portion becomes stronger, and the earthquake resistance of the battery is improved.
[0028]
The flat wound electrode battery according to the present invention can hold the flat wound electrode body because the protruding end of the flat wound electrode body is integrally joined to the positive electrode terminal and the negative electrode terminal. It can be performed at the electrode terminal, and the productivity is excellent because the holding member for the electrode body is not required. Further, since the space at the protruding end can be used as it is as a space for installing the positive and negative bipolar terminals, the volume efficiency of the flat wound electrode battery is increased.
[0029]
【Example】
Hereinafter, the present invention will be described using examples.
[0030]
As an example of the present invention, a battery having a flat wound electrode body was manufactured.
[0031]
(Example)
The battery of the embodiment of the present invention is a battery whose configuration is shown in FIG.
[0032]
The battery according to the embodiment has a flat wound electrode body 4 formed in a flat shape in a state where a strip-shaped positive electrode plate 41 and a negative electrode plate 42 and a separator 43 interposed between the two electrode plates are wound. It has a positive electrode terminal 1 and a negative electrode terminal 2 joined to the wound electrode body 4, a case 3 holding the flat wound electrode body 4 inside, and an electrolytic solution.
[0033]
The positive electrode plate 41 has a positive electrode active material layer 412 formed on both surfaces of a positive electrode current collector 413 made of a strip-shaped aluminum sheet having a width of 100 mm and a length of 4 m, and one end in the width direction of the positive electrode current collector 413. The edge portion 414 on which the positive electrode active material layer 412 is not formed is provided on the side. The edge 414 was formed with a width of 16 mm from the end. In addition, a lithium manganese oxide was used as the positive electrode active material.
[0034]
The negative electrode plate 42 has a negative electrode active material layer 422 formed on both surfaces of a negative electrode current collector 423 formed of a strip-shaped copper sheet having a width of 102 mm and a length of 4.2 m, and has one side in the width direction of the negative electrode current collector 423. Has an edge 424 where the negative electrode active material layer 422 is not formed. The edge 424 had a width of 14 mm from the end. Further, carbon was used as the negative electrode active material.
[0035]
The separator 43 is made of polyethylene or polypropylene formed in a belt shape having a width of 90 mm and a length of 4.4 m. That is, the width of the band is longer than the regions of the bipolar plates 41 and 42 where the electrode active material layers 412 and 422 are formed, and the length is longer than the bipolar plates 41 and 42.
[0036]
In the flat wound electrode body 4, the edge portions 414, 424 of the positive electrode plate 41 and the negative electrode plate 42 project from the separator 43 in directions opposite to each other in the axial direction to form projecting ends 411, 421. The protruding ends 411 and 421 are formed by joining the edges 414 and 424 in a stacked state.
[0037]
The flat wound electrode body 4 has a flat shape whose outer peripheral shape is widened in the width direction. Further, the flat wound electrode body 4 has a flat hollow portion defined on the innermost peripheral surface of the electrode plate.
[0038]
The positive electrode terminal 1 and the negative electrode terminal 2 are composed of shaft portions 11 and 21 joined to the protruding ends 411 and 421 of the flat wound electrode body 4, flange portions 12 and 22 abutting on the battery case 3, and an assembled battery. And other ends 13 and 23 formed with screws that can be used for connection during the formation and that can fix the positive electrode terminal 1 and the negative electrode terminal 2 to the case 3. The positive terminal 1 is made of aluminum, and the negative terminal 2 is made of a copper alloy.
[0039]
The positive electrode terminal 1 and the negative electrode terminal 2 joined to the protruding ends 411 and 421 extend in a direction orthogonal to the direction in which the protruding ends 411 and 421 of the flat wound electrode body 4 protrude. They are joined at the shaft portions 11 and 21. The extending direction of the positive electrode terminal 1 and the negative electrode terminal 2 was parallel to the direction in which the flat shape of the flat wound electrode body 4 spread. Further, the other ends 13 and 23 are both arranged in the same direction. FIG. 4 shows how the positive terminal 1 and the negative terminal 2 are joined to the protruding ends 411 and 421 of the flat wound electrode body 4.
[0040]
Further, the joining portions of the respective protruding ends 411 and 421 with the positive electrode terminal 1 or the negative electrode terminal 2 are joined in a state where the laminated body of the edges 414 and 424 forming the respective protruding ends 411 and 421 is compressed. Have been.
[0041]
The positive electrode terminal 1 and the negative electrode terminal 2 are fixed to the case 3 using nuts 7 with a gasket 6 made of an insulator interposed between the flange portions 12 and 22 and the case 3.
[0042]
The case is a tank-shaped container formed of stainless steel and capable of sealing the inside. The electrolytic solution is a solution obtained by adding 1 mol of LiPF ₆ to a mixed solvent of ethylene carbonate and diethylene carbonate mixed at a ratio of 3: 7. Was used.
[0043]
(Battery manufacturing method)
In the battery of the present embodiment, after forming the flat wound electrode body 4 in which the positive electrode plate 41 and the negative electrode plate 42 are wound via a separator, the protruding end portions 411, 421 of the flat wound electrode body 4 are formed. After the positive electrode terminal 1 and the negative electrode terminal 2 are welded to each other, they are sealed in a case 3 together with an electrolytic solution.
[0044]
Details will be described below.
[0045]
First, a positive electrode plate having positive electrode active material layers formed on both surfaces of a positive electrode current collector is formed. The formation of the positive electrode plate is performed by applying a paste mixture having a positive electrode active material to the surface of the positive electrode current collector, performing a drying treatment, and then pressing and pressing. Further, the formation of the negative electrode plate having the negative electrode active material layers on both surfaces of the negative electrode current collector is performed by the same means as that for the positive electrode.
[0046]
Subsequently, an edge portion was formed by removing the active material from one end in the width direction of the positive electrode plate and the negative electrode plate to expose the positive electrode current collector and the negative electrode current collector.
[0047]
After that, the positive electrode plate 41 and the negative electrode plate 42 are laminated via the separator 43. As shown in FIG. 2, the positive electrode plate 41, the negative electrode plate 42, and the separator 43 are stacked such that the edges 414 and 424 of the positive electrode plate 41 and the negative electrode plate 42 are in opposite directions and protrude from the separator 43. Layered.
[0048]
The laminated body was wound into a flat shape to form a flat wound electrode body 4 having protruding ends 411 and 421 protruding at both ends. FIG. 3 shows the state of this winding. Specifically, after winding the laminated body around a core body having an elliptical cross-sectional shape, the core body is extracted from the wound body, and the wound body is pressed to form a flat shape. Was.
[0049]
Thereafter, the protruding ends 411 and 421 in which the edges 414 and 424 arranged on both ends of the winding axis of the flat wound electrode body 4 are laminated, the positive electrode end 1 and the negative electrode arranged in a predetermined direction. The shaft portions 11 and 21 of the terminal 2 were joined. The bonding of the positive terminal 1 and the negative terminal 2 was performed by ultrasonic bonding. Specifically, ultrasonic vibration is applied to the positive terminal 1 or the negative terminal 2 in a state where the shaft portions 11 and 21 are in contact with the protruding ends 411 and 421 of the flat wound electrode body 4 while applying a pressing force. As a result, the protruding ends 411 and 421 and the shafts 11 and 21 were joined. At this time, the protruding ends 411 and 421 were also joined to the edge 414 of the positive electrode current collector or the edge 421 of the negative electrode current collector in a stacked state.
[0050]
FIG. 4 shows a flat wound electrode body 4 to which the positive electrode terminal 1 and the negative electrode terminal 2 are joined.
[0051]
The flat wound electrode body 4 to which the positive electrode terminal 1 and the negative electrode terminal 2 are joined is housed in the case 3, and the screw portions provided at the other end portions 13 and 23 of the positive electrode terminal 1 and the negative electrode terminal 2 are nuts 7. fixed. At this time, the flat wound electrode body 4 is held in the case 3 by the positive terminal 1 and the negative terminal 2.
[0052]
Thereafter, an electrolytic solution was injected into the case 3 and the case 3 was sealed, whereby the battery of Example was manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a battery of an example.
FIG. 2 is a developed view showing a configuration of a flat wound electrode used in the battery of the embodiment.
FIG. 3 is a developed view showing a flat wound electrode used in the battery of the embodiment.
FIG. 4 is a view showing a relationship between a flat wound electrode and positive and negative bipolar terminals used in the battery of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Positive electrode terminal 2 ... Negative electrode terminal 11, 21 ... Shaft part 12, 22 ... Flange part 13, 23 ... Other end part 3 ... Case 4 ... Flat wound electrode body 41 ... Positive electrode plate 42 ... Negative electrode plate 411, 421 ... Protruding end 412: Positive electrode active material layer 413: Positive electrode current collector 414 ... Perimeter 422: Negative electrode active material layer 423 ... Negative electrode current collector 424 ... Perimeter 6 ... Gasket 7 ... Nut

Claims (3)

A belt-shaped positive electrode plate and a negative electrode plate each having an electrode active material layer on both surfaces, a flat-shaped wound electrode body formed into a wound flat shape with a band-shaped separator interposed therebetween,
A positive electrode terminal and a negative electrode terminal having a shaft portion connected to the positive electrode plate and the negative electrode plate of the flat wound electrode body;
Has,
The positive electrode plate and the negative electrode plate, each edge portion where the electrode active material is not applied, protruding from the separator in the opposite direction along the axial direction of the flat wound electrode body, and the separator, An electrode portion to which the electrode active material is applied, and at least a part of the flat wound electrode body is joined to each other in a thickness direction of the flat wound electrode body in a state in which the respective peripheral portions are stacked, Forming each protruding end portion thinner than the thickness of the flat-shaped wound electrode body in which the electrode portion is laminated;
The positive electrode terminal and the negative electrode terminal are arranged on the laminating surface of each protruding end of the flat-shaped wound electrode body in a state where the shaft extends in a direction intersecting the direction in which each protruding end protrudes. And the diameter from the axis of the flat wound electrode body to the outermost surface of the shaft opposite to the contact surface of each shaft with the protruding end. A flat wound electrode battery, wherein a directional distance is shorter than a radial distance from an axial center of the electrode portion to an outer peripheral surface of the electrode portion of the flat wound electrode body. The positive electrode terminal and the negative electrode terminal have other ends protruding in a direction intersecting with a winding axis of the flat wound electrode body, and the other ends of the positive electrode terminal and the negative electrode terminal are the same. The flat-shaped wound electrode battery according to claim 1, which protrudes in the direction. The flat wound electrode battery according to claim 1, wherein the protruding end portions are integrally joined in a state where the stacked peripheral portions are compressed in a thickness direction.

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