Electrode group and secondary battery

Abstract

The objective is to provide electrode groups and secondary batteries that can be manufactured in a short time. [Solution] The electrode group of the embodiment comprises a positive electrode and a negative electrode. The electrode group is formed by winding the positive electrode and the negative electrode with a separator in between. In addition, in the electrode group of the embodiment, at least a portion of the winding of the electrode group from the starting point to the ending point of the winding is provided in which the positive electrode and the negative electrode are wound in combination in four or more layers.

Description

Technical Field

[0006] , , , ,

[0001] Embodiments of the present invention relate to an electrode group and a secondary battery.

Background Art

[0002] In recent years, secondary batteries such as lead-acid batteries and nickel-metal hydride batteries have been used as power sources represented by electric vehicles, hybrid vehicles, electric motorcycles, and forklifts. Recently, development towards the adoption of lithium-ion secondary batteries with high energy density has become active, and development has been carried out while considering long life, safety, etc.

[0003] For example, an electrode group used in a lithium-ion secondary battery (hereinafter referred to as a secondary battery) may be manufactured by winding a positive electrode and a negative electrode through a separator. In the manufacture of such a type of electrode group, one layer of a positive electrode and one layer of a negative electrode may be combined and wound, but in this case, it may take a long time to manufacture the electrode group.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide an electrode group and a secondary battery that can be manufactured in a short manufacturing time.

Means for Solving the Problems

[0006] To solve the above problems, the electrode group of the embodiment comprises a positive electrode and a negative electrode, wherein the positive electrode and the negative electrode are wound together with a separator, and at least a portion of the electrode group from the starting point to the ending point of the winding has a portion in which the positive electrode and the negative electrode are wound together in four or more layers. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic perspective view showing the electrode group according to the first embodiment. [Figure 2] A partially unfolded perspective view of the electrode group according to the first embodiment, viewed from above. [Figure 3] A schematic cross-sectional view showing the electrode group according to the first embodiment. [Figure 4] A schematic cross-sectional view showing a modified example of the electrode group according to the first embodiment. [Figure 5] A schematic perspective view showing a secondary battery according to the second embodiment. [Modes for carrying out the invention]

[0008] The electrode group and secondary battery of the embodiment will be described below with reference to the drawings.

[0009] (First embodiment) The electrode group 5 of the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic perspective view of the electrode group 5 according to the first embodiment, and Figure 2 is a partially unfolded perspective view of the electrode group 5 according to the first embodiment viewed from above. The electrode group 5 of the present invention is composed of four or more layers of positive electrodes 13 and negative electrodes 15, but Figure 2 will describe two of these layers, the positive electrode 13 and the negative electrode 15.

[0010] The electrode group 5 is manufactured, for example, as shown in Figures 1 and 2, by winding the positive electrode 13 and the negative electrode 15 around a separator 4 and then press-molding the entire assembly into a flattened shape in the stacking direction (Y direction) of the positive electrode 13 and the negative electrode 15. This press-molding reduces the space within the electrode group 5, so when housing the electrode group 5 in a secondary battery case, for example, more positive electrodes 13 and negative electrodes 15 can be accommodated in the limited space within the case. However, the manufacturing method of the electrode group 5 is not limited to these methods; it is sufficient as long as the positive electrode 13 and the negative electrode 15 are wound around a separator 4.

[0011] The positive electrode 13 has a strip-shaped positive electrode current collector 13a having a long side 90 (Z direction) and a short side 92 (X direction). On the positive electrode current collector 13a, there is a positive electrode mixture layer 130 in which the positive electrode agent is applied parallel to the long side 90, and an uncoated portion 70a of the positive electrode mixture layer where the positive electrode agent is not applied. The negative electrode 15 has a strip-shaped negative electrode current collector 15a having a long side 90 and a short side 92. On the negative electrode current collector 15a, there is a negative electrode mixture layer 150 in which the negative electrode mixture is applied parallel to the long side 90, and an uncoated portion 70b of the negative electrode mixture layer where the negative electrode agent is not applied.

[0012] In the wound electrode group 5 of this embodiment, the uncoated portion 70a of the positive electrode mixture layer protrudes in the opposite direction to the protruding direction of the uncoated portion 70b of the negative electrode mixture layer and is provided at both ends of the electrode group 5. However, the protruding directions of the uncoated portion 70a of the positive electrode mixture layer and the uncoated portion 70b of the negative electrode mixture layer are not limited to these. The uncoated portion 70a of the positive electrode mixture layer and the uncoated portion 70b of the negative electrode mixture layer may protrude in the same direction, and both may be provided at one end of the electrode group 5.

[0013] The electrode group 5 will be further explained with reference to Figure 3. Figure 3 is a schematic cross-sectional view (cross-section II shown in Figure 1) of the electrode group 5 according to the first embodiment.

[0014] In this embodiment, as shown in Figure 3, the electrode group 5 is wound with four or more layers of positive electrode 13 and negative electrode 15 combined in at least a portion of the winding from the starting point P to the ending point P' of the electrode group 5. By combining four or more layers of positive electrode 13 and negative electrode 15 in at least a portion of the electrode group 5, the manufacturing time of the electrode group 5 can be shortened when manufacturing an electrode group 5 with the same battery capacity as an electrode group 5 manufactured by combining and winding one layer of positive electrode 13 and one layer of negative electrode 15. Here, it is sufficient that four or more layers of positive electrode 13 and negative electrode 15 are combined in at least a portion of the electrode group 5, and as shown in Figure 3, the portion after one turn from the starting point P may have only two layers of positive electrode 13 and negative electrode 15.

[0015] In this embodiment, the electrode group 5 is configured such that at least a portion of the electrode group 5 consists of four or more layers of positive electrodes 13 and negative electrodes 15, but it is preferable that the number of layers of each of the positive electrodes 13 and negative electrodes 15 are equal. For example, this could involve combining two layers of positive electrodes 13 with two layers of negative electrodes 15, or combining three layers of positive electrodes 13 with three layers of negative electrodes 15. As a result, in the electrode group 5 after winding, the positive electrodes 13 and negative electrodes 15 face each other via the separator 4, and an electrode group 5 with guaranteed battery capacity can be obtained.

[0016] Furthermore, in Figure 3, the positive electrode 13 is positioned at the innermost circumference of the electrode group 5, but the electrode positioned at the innermost circumference may be either the positive electrode 13 or the negative electrode 15.

[0017] A modified example of electrode group 5 will be described with reference to Figure 4. Figure 4 is a schematic cross-sectional view (cross-section II shown in Figure 1) illustrating a modified example of electrode group 5 according to the first embodiment.

[0018] In a modified example of the electrode group 5, as shown in FIG. 4, two layers of positive electrodes 13 and two layers of negative electrodes 15 are wound in combination from the starting point P to the ending point P' in the winding of the electrode group 5. By combining two layers of positive electrodes 13 and two layers of negative electrodes 15 from the starting point P to the ending point P' of the electrode group 5, when manufacturing an electrode group 5 with the same battery capacity as the electrode group 5 manufactured by winding one layer of positive electrode 13 and one layer of negative electrode 15 in combination, the manufacturing time of the electrode group 5 can be shortened. Specifically, in the modified example of the electrode group 5, when manufacturing an electrode group 5 with the same battery capacity as the electrode group 5 manufactured by winding one layer of positive electrode 13 and one layer of negative electrode 15 in combination, the manufacturing time of the electrode group 5 is approximately halved.

[0019] In the modified example of the electrode group 5, two layers of positive electrodes 13 and two layers of negative electrodes 15 are combined from the starting point P to the ending point P' of the electrode group 5. However, since the positive electrode 13 and the negative electrode 15 are continuously combined from the starting point P to the ending point P', there is no need for a process of increasing or decreasing the number of positive electrodes 13 or negative electrodes 15 during winding, and the electrode group 5 can be easily manufactured from the starting point P to the ending point P'.

[0020] Also, in the modified example of the electrode group 5, since both the positive electrode 13 and the negative electrode 15 are two layers, compared with the case where five or more layers of the positive electrode 13 and the negative electrode 15 are combined, the electrode group 5 is less likely to be misaligned due to the combination of the positive electrode 13 and the negative electrode 15. Thereby, for example, when the electrode group 5 is housed in the case of a secondary battery, the electrode group 5 can be appropriately housed in the case, and a short circuit between the positive electrode 13 and the negative electrode 15 due to misalignment can also be suppressed.

[0021] In the electrode group 5 of the first embodiment described above, at least a part from the starting point P to the ending point P' in the winding of the electrode group 5, the positive electrode 13 and the negative electrode 15 are wound in combination with four or more layers. Thereby, when manufacturing an electrode group 5 with the same battery capacity as the electrode group 5 manufactured by winding one layer of positive electrode 13 and one layer of negative electrode 15 in combination, the manufacturing time of the electrode group 5 can be shortened, and an electrode group 5 that can be manufactured in a short manufacturing time can be provided.

[0022] (Second Embodiment) The secondary battery 1 of the second embodiment will be described with reference to Figure 5. Figure 5 is a schematic perspective view showing the secondary battery 1 according to the second embodiment.

[0023] As shown in Figure 5, the secondary battery 1 has an outer case 3, and the electrode group 5 with a wound structure according to the first embodiment is housed inside the outer case 3. Inside the outer case 3, the electrode group 5 is impregnated with an electrolyte (not shown), and the electrolyte is injected, for example, through an injection port (not shown) provided on the lid member 7, and the injection port is sealed with a sealing plate 19 after the electrolyte has been injected. The electrolyte used is a non-aqueous electrolyte prepared by dissolving an electrolyte (e.g., a lithium salt) in a non-aqueous solvent. The non-aqueous solvent may be used alone or in a mixture of two or more types.

[0024] A gas discharge valve 21 may be provided on the surface of the lid member 7 together with the sealing plate 19. Furthermore, for example, a pair of positive electrode external terminals 23a and negative electrode external terminals 23b are attached to the surface of the lid member 7, and the external terminals 23a and 23b are electrically connected to the uncoated portion 70a of the positive electrode mixture layer and the uncoated portion 70b of the negative electrode mixture layer of the electrode group 5, respectively. A terminal insulator 35 may be provided between the external terminals 23a and 23b and the lid member 7 to maintain insulation between them.

[0025] The secondary battery 1 of the second embodiment described above is equipped with the electrode group 5 of the first embodiment. Since the electrode group 5 of the first embodiment can be manufactured in a short time, if this electrode group 5 is used in the secondary battery 1, the manufacturing time of the secondary battery 1 can also be shortened. This makes it possible to provide a secondary battery 1 that can be manufactured in a short time.

[0026] According to the electrode group 5 of at least one embodiment described above, in at least a portion of the winding of the electrode group 5 from the starting point P to the ending point P', the positive electrode 13 and the negative electrode 15 are wound in combination in four or more layers. As a result, when manufacturing an electrode group 5 with the same battery capacity as an electrode group 5 manufactured by winding together one layer of positive electrode 13 and one layer of negative electrode 15, the manufacturing time of the electrode group 5 can be shortened, and an electrode group 5 that can be manufactured in a short time can be provided.

[0027] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0028] 1...Secondary battery, 3...Outer case, 4...Separator, 5...Electrode group, 7...Lid member, 13...Positive electrode, 13a...Positive electrode current collector, 15...Negative electrode, 15a...Negative electrode current collector, 19...Sealing plate, 21...Gas discharge valve, 23a...Positive electrode external terminal, 23b...Negative electrode external terminal, 35...Terminal insulator, 70a...Uncoated part of positive electrode mixture layer, 70b...Uncoated part of negative electrode mixture layer, 90...Long side, 92...Short side, 130...Positive electrode mixture layer, 150...Negative electrode mixture layer.

Claims

1. Equipped with a positive electrode and a negative electrode, An electrode group in which the positive electrode and the negative electrode are wound around each other via a separator, An electrode group wherein at least a portion of the electrode group from the starting point to the ending point of the winding has a portion in which the positive electrode and the negative electrode are wound together in combination in four or more layers.

2. The electrode group according to claim 1, wherein two layers of the positive electrode and two layers of the negative electrode are combined and wound together from the starting point of the winding of the electrode group to the ending point of the winding.

3. A group of electrodes as described in any one of claims 1 to 2, A secondary battery comprising an electrolyte.

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