Electrode body and secondary battery

Abstract

The present invention provides an electrode body and a secondary battery that reduce the amount of metal used while facilitating the flow of current between the electrode and the battery terminals. [Solution] An electrode body 20 is formed by winding a strip-shaped first electrode plate and a strip-shaped second electrode plate along the longitudinal direction via a separator 60b, wherein the first electrode plate has a first base material made of resin, a first metal layer formed on the first base material, and a first active material layer formed on the first metal layer, the first metal layer has a first exposed portion E1 at one end in the winding axis direction X of the electrode body where the first active material layer is not formed, the length of the first exposed portion E1 in the winding axis direction X decreases from one end to the other in the longitudinal direction, and a first electrode joint portion 21 is formed where the first exposed portion E1 is exposed sequentially from one end in the longitudinal direction.

Description

Technical Field

[0001] The present invention relates to an electrode body and a secondary battery of a secondary battery.

Background Art

[0002] In recent years, batteries such as lithium-ion secondary batteries have been suitably used as power sources for driving vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). In this type of battery, for example, an electrode body is housed in a case. As a battery having such a configuration, for example, the battery described in Patent Document 1 below is disclosed.

[0003] The battery described in Patent Document 1 has an electrode body housed in a battery case, and a positive electrode terminal and a negative electrode terminal are connected to the electrode body. Specifically, in the battery described in Patent Document 1, the current collecting portion of the positive electrode terminal is electrically connected to the positive electrode of each electrode body inside the battery case, and the current collecting portion of the negative electrode terminal is electrically connected to the negative electrode of each electrode body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In secondary batteries, the electrode body is equipped with positive and negative metal foils for collecting current. Since aluminum and copper, which are used in the metal foil, are expensive, reducing their usage will have a significant cost-reduction effect on secondary batteries. Also, because these metals have a high specific gravity, reducing their usage will also make secondary batteries lighter. However, secondary batteries require a certain strength to be transported with the metal foil attached, so reducing the amount of metal used by thinning the metal foil is not easy. Therefore, as a method to reduce the amount of metal used while ensuring the strength of the metal foil, the use of electrode plates in which aluminum or copper is thinly coated on a resin substrate by sputtering or the like can be considered. However, in this case, since there is resin in the center in the thickness direction of the electrode plate, even if current collection terminals are welded to the aluminum or copper on the outer circumference of the electrode body formed by winding the electrode plate, current does not easily flow to the inside of the winding body.

[0006] Therefore, as with the secondary battery described in Patent Document 2, a complex process was required to connect a separately manufactured electrical connection member to the electrode plate and weld a current collection terminal to the electrical connection member. Thus, in secondary batteries, there was room for improvement in maintaining the strength of the current-collecting metal foil while facilitating the flow of current through the electrode body (winding body).

[0007] This invention has been made in view of the above circumstances, and its purpose is to provide an electrode body and a secondary battery that can facilitate the flow of current between the electrode body and the battery terminals while reducing the amount of metal used. [Means for solving the problem]

[0008] The characteristic configuration of the electrode body according to the present invention for achieving the above objective is as follows: An electrode body comprising a strip-shaped first electrode plate and a strip-shaped second electrode plate wound along the longitudinal direction with a separator in between, The first electrode plate comprises a first substrate made of resin, a first metal layer formed on the first substrate, and a first active material layer formed on the first metal layer. The first metal layer has a first exposed portion at one end in the winding axis direction of the electrode body, where the first active material layer is not formed. The length of the first exposed portion decreases in the winding axis direction as it moves from one end to the other end in the longitudinal direction. The first exposed portion is formed in which a first electrode junction is exposed sequentially from one end in the longitudinal direction.

[0009] According to the above characteristic configuration, by forming a first electrode plate containing a first metal layer on a first resin substrate, the amount of expensive metal materials such as aluminum and copper that can be used as the first metal can be reduced, thereby reducing the manufacturing cost of the electrode body. Furthermore, the electrode body is constructed by winding a first electrode plate, the length in the winding axis direction decreasing from one end in the longitudinal direction to the other end. As a result, at one end of the first electrode plate in the winding axis direction, a first electrode joint is formed where the first exposed portion is exposed sequentially from one end in the longitudinal direction, and an exposed portion of the first metal layer is obtained. Thus, a joint between the first electrode plate and the battery terminal can be secured, and electrical conductivity between the electrode body and the battery terminal can be easily ensured. In this way, the electrode body can reduce the amount of metal used while facilitating current flow between it and the battery terminal.

[0010] Further characteristic features of the electrode body according to the present invention are: The aforementioned second electrode plate comprises a second substrate made of resin, a second metal layer formed on the second substrate, and a second active material layer formed on the second metal layer. The second metal layer has a second exposed portion at the other end in the winding axis direction where the second active material layer is not formed. The length of the second exposed portion decreases in the winding axis direction as it moves from one end to the other end, or from the other end to one end, in the longitudinal direction. The second exposed portion is formed in which a second electrode junction is exposed sequentially from one end in the longitudinal direction, or from the other end.

[0011] According to the above-described configuration, for example, by using the first electrode plate as the positive electrode and the second electrode plate as the negative electrode, the amount of metal used for both the positive and negative electrodes can be reduced, further lowering the manufacturing cost of the electrode body. In addition, since a second electrode junction is formed on the second electrode plate, an exposed portion of the second metal layer is obtained, ensuring a junction between the second electrode plate and the battery terminal, making it easier to ensure conductivity between the electrode body and the battery terminal.

[0012] Further characteristic features of the electrode body according to the present invention are: The first electrode plate has the first metal layer formed on the front and back surfaces of the first substrate, and the first active material layer formed on each of the first metal layers. The second electrode plate has the second metal layer formed on the front and back surfaces of the second substrate, and the second active material layer formed on each of the second metal layers. The first electrode plate and the second electrode plate are wound together in a state where they are stacked on top of each other with the first active material layer and the second active material layer facing each other, with the separator in between.

[0013] According to the above characteristic configuration, the first electrode plate and the second electrode plate can be manufactured separately, so only the electrode layer formed on the resin substrate during manufacturing needs to be changed, and the manufacturing process of the electrode body does not become complicated.

[0014] Further characteristic features of the electrode body according to the present invention are: A single substrate is composed of the aforementioned first substrate and the aforementioned second substrate. The first metal layer and the first active material layer are formed on one side of the substrate, and the second metal layer and the second active material layer are formed on the other side. The second exposed portion is characterized by a decrease in length in the winding axis direction as it moves from the other end to the one end in the longitudinal direction.

[0015] According to the above characteristic configuration, the formation of the metal layer and the corresponding active material layer only needs to be on one side, which simplifies the manufacturing process of the electrode body compared to the case where each metal layer and active material layer is formed on both sides of the substrate.

[0016] The characteristic configuration of the secondary battery according to the present invention for achieving the above object is as follows: a battery case, an electrode body housed in the battery case, and a first battery terminal electrically connected to the electrode body. The electrode body is formed by winding a strip-shaped first electrode plate and a strip-shaped second electrode plate along the longitudinal direction with a separator interposed therebetween. The first electrode plate has a first base material made of resin, a first metal layer formed on the first base material, and a first active material layer formed on the first metal layer. The first metal layer has a first exposed portion where the first active material layer is not formed at one end in the winding axis direction of the electrode body. The length of the first exposed portion in the winding axis direction decreases from one end side to the other end side in the longitudinal direction. A first electrode joint portion where the first exposed portion is sequentially exposed from one end side in the longitudinal direction is formed. The first battery terminal is joined to the first electrode joint portion.

[0017] According to the above characteristic configuration, by forming the first electrode plate including the first metal layer on the resin-made first base material, the amount of expensive metal materials such as aluminum and copper that can be used as the first metal can be reduced, and the manufacturing cost of the secondary battery can be reduced. In addition, an electrode member in which the length of the first electrode plate in the winding axis direction decreases from one end side to the other end side in the longitudinal direction is wound. Therefore, at one end side in the winding axis direction of the electrode body, a first electrode joint portion where the first exposed portion is sequentially exposed from one end side in the longitudinal direction is formed, and an exposed portion of the first metal layer is obtained. Thus, a joint portion between the first electrode plate and the battery terminal can be secured, and it becomes easier to secure electrical continuity between the electrode body and the battery terminal. In this way, in the above secondary battery, while reducing the amount of metal used for the electrode body, it is possible to easily allow current to flow between the electrode body and the battery terminal.

[0018] Further characteristic features of the secondary battery according to the present invention are: The electrode body further comprises a second battery terminal electrically connected to the electrode body, The aforementioned second electrode plate comprises a second substrate made of resin, a second metal layer formed on the second substrate, and a second active material layer formed on the second metal layer. The second metal layer has a second exposed portion at the other end in the winding axis direction where the second active material layer is not formed. The length of the second exposed portion decreases in the winding axis direction as it moves from one end to the other end, or from the other end to one end, in the longitudinal direction. The second exposed portion is formed by exposing the second electrode joint portion sequentially from one end in the longitudinal direction, or exposing it from the other end. The second battery terminal is connected to the second electrode junction.

[0019] According to the above-described configuration, for example, by using the first electrode plate as the positive electrode and the second electrode plate as the negative electrode, the amount of both positive and negative electrode plate material used can be reduced, further lowering the manufacturing cost of the secondary battery. In addition, since the second electrode plate of the secondary battery has a second electrode junction formed thereon, an exposed portion of the second metal layer is obtained, which ensures a connection between the second electrode plate and the battery terminals, making it easier to ensure conductivity between the electrode body and the battery terminals.

[0020] Further characteristic features of the secondary battery according to the present invention are: The first electrode junction is located at the point where the first exposed portion is exposed on the outside of the electrode body, and the second electrode junction is located at the point where the second exposed portion is exposed on the outside of the electrode body.

[0021] According to the above characteristic configuration, the first electrode plate and the second electrode plate can be manufactured separately, so only the electrode layer formed on the substrate during manufacturing needs to be changed, and the secondary battery manufacturing process does not become complicated.

[0022] Further characteristic features of the secondary battery according to the present invention are: A single substrate is composed of the aforementioned first substrate and the aforementioned second substrate. The first metal layer and the first active material layer are formed on one side of the substrate, and the second metal layer and the second active material layer are formed on the other side. The length of the second exposed portion decreases in the winding axis direction as it moves from the other end to the one end in the longitudinal direction. The first electrode junction is located at the point where the first exposed portion is exposed on the outside of the electrode body, and the second electrode junction is located at the point where the second exposed portion is exposed on the inside of the electrode body.

[0023] According to the above characteristic configuration, the formation of the metal layer and the corresponding active material layer only needs to be done on one side, which simplifies the manufacturing process of the secondary battery compared to the case where each metal layer and active material layer is formed on both sides of the resin substrate. [Effects of the Invention]

[0024] As described above, the electrode body and secondary battery according to the present invention make it possible to reduce the amount of metal used while facilitating the flow of current between them and the battery terminals. [Brief explanation of the drawing]

[0025] [Figure 1] This is an exploded perspective view of a secondary battery according to the first embodiment. [Figure 2] This diagram shows the plan view of the positive electrode plate and the winding process in progress. [Figure 3] This is a cross-sectional view of the positive electrode plate. [Figure 4] This diagram shows a plan view of the negative electrode plate and a diagram showing the winding process. [Figure 5] This is a cross-sectional view of the negative electrode plate. [Figure 6] This is a cross-sectional view of the electrode body before winding. [Figure 7] This is a perspective view of the electrode body after winding. [Figure 8] This figure shows the manufacturing process of the positive and negative electrode plates that constitute the electrode body according to the second embodiment. [Figure 9] This is a cross-sectional view of the electrode body of the second embodiment before the winding stage. [Figure 10] This is a perspective view of the electrode body of the second embodiment after winding. [Modes for carrying out the invention]

[0026] Hereinafter, an electrode body and a secondary battery according to an embodiment of the present invention will be described with reference to the drawings. In the following description, a lithium-ion secondary battery equipped with an electrode body will be used as an example. Furthermore, in order to clarify the explanation, the descriptions and drawings have been simplified as appropriate. First, a first embodiment of the present invention will be described.

[0027] [Overview of secondary battery 1] Figure 1 is an exploded perspective view of a secondary battery 1 equipped with an electrode body 20 according to this embodiment. In the following description, the direction parallel to the height direction of the secondary battery 1 is defined as the Z-axis direction, the direction parallel to the longitudinal direction of the electrode body 20 is defined as the X-axis direction, and the direction parallel to the thickness direction of the electrode body 20 is defined as the Y-axis direction. The Z-axis direction is parallel to the vertical direction, the X-axis direction and the Y-axis direction are orthogonal to each other and parallel to the horizontal direction. In the following, one side in the X-axis direction will be referred to as the X1 side, and the other side in the X-axis direction will be referred to as the X2 side.

[0028] As shown in Figure 1, the secondary battery 1 comprises a battery case 10 consisting of a case body 11 and a sealing plate 12, battery terminals PS (an example of a first battery terminal) and NS (an example of a second battery terminal) consisting of metal external terminals 25 and 26 and current collector terminals 30 and 31, and an electrode body 20. The secondary battery 1 is a sealed type secondary battery in which the electrode body 20 and current collector terminals 30 and 31 are housed inside the case body 11, the opening of the case body 11 is sealed with the sealing plate 12, and then an electrolyte is injected into the inside of the case body 11.

[0029] [Configuration of battery case 10] As shown in Figure 1, the battery case 10 consists of a case body 11 with a roughly rectangular parallelepiped shape and an open top, and a sealing plate 12 that seals the opening of the case body 11. In this embodiment, both the case body 11 and the sealing plate 12 are made of aluminum, but are not limited to this. Various metals and alloys can be appropriately selected for the case body 11 and the sealing plate 12 depending on the type and application of the battery.

[0030] In this embodiment, the sealing plate 12 has a shape corresponding to the shape of the opening of the case body 11 and is configured to seal the opening of the case body 11.

[0031] [Battery terminal configuration PS, NS] In this embodiment, the secondary battery 1 is equipped with a positive external terminal 25 and a negative external terminal 26 as external terminals, and a positive current collector terminal 30 and a negative current collector terminal 31 as current collector terminals. The positive battery terminal PS is composed of the positive external terminal 25 and the positive current collector terminal 30, and the negative battery terminal NS is composed of the negative external terminal 26 and the negative current collector terminal 31. In this embodiment, the positive external terminal 25 and the positive current collector terminal 30 are made of aluminum, and the negative external terminal 26 and the negative current collector terminal 31 are made of copper, but the materials of these terminals are not particularly limited, and various metals and alloys with good conductivity can be used.

[0032] Furthermore, in this embodiment, the secondary battery 1 includes a positive electrode insulating member (not shown), a negative electrode insulating member (not shown), a positive electrode gasket 32, and a negative electrode gasket 33, all of which are made of insulating material. In this embodiment, PFA resin is used as the insulating material, but the invention is not limited to this.

[0033] The positive electrode current collector terminal 30 has a positive electrode current collector portion 30a extending downward from the back surface of a flat surface (not shown). The negative electrode current collector terminal 31 has a negative electrode current collector portion 31a extending downward from the back surface of a flat surface (not shown). The tip of the positive electrode current collector portion 30a is joined to a positive electrode terminal joint portion 21, which will be described later, and the tip of the negative electrode current collector portion 31a is joined to a negative electrode terminal joint portion 22, which will be described later.

[0034] Although a detailed explanation will be omitted, in the secondary battery 1 of this embodiment, the positive electrode external terminal 25 and the negative electrode external terminal 26 are insulated from the sealing plate 12 by a positive electrode gasket 32 ​​and a negative electrode gasket 33, respectively, and the positive electrode current collector terminal 30 and the negative electrode current collector terminal 31 are insulated from the sealing plate 12 by a positive electrode insulating member and a negative electrode insulating member, respectively.

[0035] [Configuration of electrode body 20] In this embodiment, the electrode body 20 is composed of a wound body formed by winding together a long, strip-shaped positive electrode plate 40 (an example of a first electrode plate, see Figure 2) and a negative electrode plate 50 (an example of a second electrode plate, see Figure 4) that are stacked via strip-shaped separators 60a and 60b (see Figure 6), and then compressing them into a flattened shape. As shown in Figure 1, the electrode body 20 of this embodiment is substantially rectangular in thickness direction (Y-axis direction), with a positive electrode terminal joint portion 21 (an example of a first electrode joint portion) formed on one end in the longitudinal direction (X-axis direction) in thickness direction, and a negative electrode terminal joint portion 22 (an example of a second electrode joint portion) formed on the other end.

[0036] In this embodiment, the electrode body 20 is housed inside the case body 11 in a position where its thickness and longitudinal directions are parallel to the horizontal direction, while covered with an insulating film. Furthermore, the electrode body 20 and the case body 11 are insulated from each other by an insulating film (not shown).

[0037] [Specific configuration of electrode body 20] Next, the detailed configuration of the electrode body 20 will be described with reference to Figures 2 to 7. Figure 2 is a plan view of the positive electrode plate (an example of the first electrode plate) and a diagram showing the winding process. Figure 3 is a cross-sectional view of the positive electrode plate. As shown in Figures 2 and 3, the positive electrode plate 40 of the electrode body 20 has a first base material 41 made of resin, first metal layers 42A and 42B formed on the first base material 41, and first composite material layers 43A and 43B (an example of the first active material layer) formed on the first metal layers 42A and 42B. For the first base material 41, a resin material with excellent strength, heat resistance, and chemical resistance, such as polyimide, is used.

[0038] The positive electrode plate 40 has first metal layers 42A and 42B formed by depositing a highly conductive metal (aluminum in this embodiment) onto both sides (front and back) of a rectangular first substrate 41. First composite layers 43A and 43B are laminated on the first metal layers 42A and 42B, respectively. The positive electrode plate 40 has the first composite layers 43A and 43B arranged on all sides of the first metal layers 42A and 42B except for one side (X1 side) in the width direction (X-axis direction). The X-axis direction is parallel to the winding axis direction of the electrode body 20. The first composite layers 43A and 43B are formed, for example, by coating the first metal layers 42A and 42B in a slurry, and contain at least the active material that constitutes the positive electrode. The first composite layers 43A and 43B may also contain a conductive material and a binder.

[0039] In the positive electrode plate 40, the first metal layers 42A and 42B have a first exposed portion E1 at one end in the X-axis direction (the X1 side end) where the first composite material layers 43A and 43B are not formed (i.e., the first metal layers 42A and 42B are exposed). In this embodiment, one side of the rectangular positive electrode plate 40 in the X-axis direction (the X1 side) is cut such that one side 40A is the longer side and the other side 40B is the shorter side in the longitudinal direction perpendicular to the X-axis direction. Note that C1 shown in Figures 2 and 3 is the cutting line. As a result, the first exposed portion E1 has a shape in which the length in the X-axis direction decreases from one end (side 40A) to the other end (side 40B) in the longitudinal direction. The trapezoidal positive electrode plate 40 is then wound from the long side, edge 40A, so that the first exposed portion E1 overlaps with a predetermined width W1 offset in the X-axis direction (see Figure 7), with one end in the longitudinal direction positioned on the inside and the other end on the outside. This forms a positive electrode terminal joint 21 in which the first exposed portion E1 is exposed sequentially from one end in the longitudinal direction.

[0040] Next, the negative electrode plate 50 will be described. Figure 4 is a plan view of the negative electrode plate 50 (an example of a second electrode plate) and a diagram showing the winding process. Figure 5 is a cross-sectional view of the negative electrode plate 50. As shown in Figures 4 and 5, the negative electrode plate 50 of the electrode body 20 has a second base material 51 made of resin, second metal layers 52A and 52B formed on the second base material 51, and second composite material layers 53A and 53B (an example of a second active material layer) formed on the second metal layers 52A and 52B. Similar to the first base material 41, the second base material 51 is made of a resin material with excellent strength, heat resistance, and chemical resistance, such as polyimide.

[0041] The negative electrode plate 50 has second metal layers 52A and 52B formed by depositing a highly conductive metal (copper in this embodiment) onto both sides (front and back) of a rectangular second substrate 51. Second composite material layers 53A and 53B are laminated on the second metal layers 52A and 52B, respectively. The negative electrode plate 50 has the second composite material layers 53A and 53B arranged on all sides of the second metal layers 52A and 52B except for the other side (X2 side) in the width direction (X axis direction). The second composite material layers 53A and 53B are formed, for example, by coating the second metal layers 52A and 52B in slurry form, and contain at least the active material that constitutes the negative electrode. The composite material layers 53A and 53B may also contain a conductive material and a binder, etc.

[0042] In the negative electrode plate 50, the second metal layers 52A and 52B have a second exposed portion E2 at the other end in the X-axis direction (the X2 side end) where the second composite material layers 53A and 53B are not formed (i.e., the second metal layers 52A and 52B are exposed). In this embodiment, the other side in the X-axis direction (X2 side) of the rectangular negative electrode plate 50 is cut such that one side 50A is the longer side and the other side 50B is the shorter side in the longitudinal direction perpendicular to the X-axis direction. Note that C2 shown in Figures 4 and 5 is the cutting line. As a result, the second exposed portion E2 has a shape in which the length in the X-axis direction decreases from one end (side 50A) to the other end (side 50B) in the longitudinal direction. The trapezoidal negative electrode plate 50 is then wound from the longer side, edge 50A, causing the second exposed portion E2 to overlap with a predetermined width W2 offset in the X-axis direction (see Figure 7), with one end in the longitudinal direction positioned on the inside and the other end on the outside. This forms a negative electrode terminal joint 22 in which the second exposed portion E2 is exposed sequentially from one end in the longitudinal direction.

[0043] Figure 6 is a cross-sectional view of the electrode body 20 before winding. Figure 7 is a perspective view of the electrode body 20 after winding. As shown in Figure 6, before winding, the positive electrode plate 40 and the negative electrode plate 50 constituting the electrode body 20 are laminated with separators 60a and 60b in between. The separators 60a and 60b are made of a porous insulating resin material that allows lithium ions to pass through. Separator 60a is positioned to insulate the first composite layer 43B of the positive electrode plate 40 from the second composite layer 53A of the negative electrode plate 50. Separator 60b insulates the first composite layer 43A of the positive electrode plate 40 and the second composite layer 53B of the negative electrode plate 50, which face each other during winding, and is positioned on the outermost periphery after winding. Specifically, separator 60b is positioned on the second composite layer 53B of the negative electrode plate 50.

[0044] As shown in Figures 6 and 7, the electrode body 20 is wound along the longitudinal direction with a strip-shaped positive electrode plate 40 and a strip-shaped negative electrode plate 50 via separators 60a and 60b. Specifically, the positive electrode plate 40 and the negative electrode plate 50 are stacked such that the first composite layer 43B and the second composite layer 53A face each other with the separator 60a in between, and the first exposed portion E1 is on the X1 side and the second exposed portion E2 is on the X2 side, with the separator 60b placed on the second composite layer 53B of the negative electrode plate 50. As a result, as shown in Figure 7, a positive electrode terminal joint 21 with the first exposed portion E1 exposed is formed on one side of the electrode body 20 in the X-axis direction (X1 side), and a negative electrode terminal joint 22 with the second exposed portion E2 exposed is formed on the other side of the electrode body 20 in the X-axis direction (X2 side). Figure 7 shows the electrode body 20 in its state after winding but before being formed into a flat shape.

[0045] Furthermore, at the positive terminal joint 21, the first exposed portion E1 exposes the annular portion 42Ba sequentially from one end in the longitudinal direction of the positive electrode plate 40. Similarly, at the negative terminal joint 22, the second exposed portion E2 exposes the annular portion 52Ba sequentially from one end in the longitudinal direction. The widths W1 and W2 of the annular portions 42Ba and 52Ba are such that a wider width makes it easier to secure the joint with the positive electrode current collector 30a and the negative electrode current collector 31a, but if they are too wide, it becomes difficult to miniaturize the secondary battery. Therefore, it is preferable that the widths W1 and W2 are the minimum widths that can secure the above-mentioned joint. The widths W1 and W2 can be appropriately adjusted by changing the shape of the first exposed portion E1 and the second exposed portion E2, the longitudinal dimensions of the positive electrode plate 40 and the negative electrode plate 50, and the winding method. In this embodiment, the widths W1 and W2 are set to, for example, 20 μm or more and 40 μm or less.

[0046] Thus, in this embodiment, since the metal layers 42A, 42B, 52A, and 52B are formed on the resin base materials 41 and 51, the amount of metal used can be reduced, and manufacturing costs can be reduced. In addition, at each electrode joint 21 and 22, the exposed portions E1 and E2 are exposed sequentially from one end in the longitudinal direction of each electrode plate 40 and 50, and exposed portions of each metal layer 42A, 42B, 52A, and 52B are obtained. As a result, the joints between each metal layer 42A, 42B, 52A, and 52B of each electrode plate 40 and 50 and the current collection portions 30a and 31a of each current collection terminal 30 and 31 can be secured, and current can be easily flowed between the electrode body 20 and each battery terminal PS and NS.

[0047] [Second Embodiment] The electrode body 20 of the second embodiment will be described with reference to Figures 8 to 10. Figure 8 is a diagram showing the manufacturing process of the positive and negative electrode plates 70 of the electrode body 20. Figure 9 is a cross-sectional view of the electrode body 20 before winding. Figure 10 is a perspective view of the electrode body 20.

[0048] The manufacturing process of the positive and negative electrode plates 70 will be explained with reference to Figure 8. First, a rectangular resin substrate 71 is prepared (step #01). Here, the substrate 71 is a component that serves as both the first substrate 41 and the second substrate 42 of the first embodiment, and a resin material with excellent strength, heat resistance, and chemical resistance, such as polyimide, is used. Next, a metal for the positive electrode is deposited on one side of the substrate 71 as a first metal layer 72 (step #02). Here, the first metal layer 72 is not formed on one end of the substrate 71 in the X-axis direction (X1 side).

[0049] Next, a first composite material layer 74 (an example of a first active material layer) is formed on the first metal layer 72 (step #03). Specifically, the first composite material layer 74 is formed by applying a slurry to the first metal layer 72. Here, the first composite material layer 74 is not formed on the other end of the first metal layer 72 in the X-axis direction (X2 side). The area of ​​the first metal layer 72 where the first composite material layer 74 is not laminated becomes the first exposed portion E3. Next, the base material 71 and the first metal layer 72 are cut such that one side 50A is the long side and the other side 50B is the short side in the longitudinal direction perpendicular to the width direction (X-axis direction) of the first exposed portion E3 (step #04). C3 shown in step #04 of Figure 8 is the cutting line.

[0050] Next, the substrate 71 is turned over. This positions the first exposed portion E3 on one side in the X-axis direction (X1 side) (see Figures 9 and 10). Then, a metal for the negative electrode is deposited on the other side of the substrate 71 as the second metal layer 73 (step #05). Next, a second composite layer 75 (an example of a second active material layer) is formed on the second metal layer 73 (step #06). Specifically, the second composite layer 75 is formed by applying a slurry to the second metal layer 73. Here, the second composite layer 75 is not formed on the other end of the second metal layer 73 in the X-axis direction (X2 side). The region of the second metal layer 73 where the second composite layer 75 is not laminated becomes the second exposed portion E4. Next, the base material 71 and the second metal layer 73 are cut so that one side 70B and the other side 70A in the longitudinal direction perpendicular to the width direction (X-axis direction) of the second exposed portion E4 are of the same length (step #07). C4 shown in step #07 in Figure 8 is the cutting line. The second exposed portion E4 is located at the X2 end of the positive and negative electrode plates 70, opposite to the first exposed portion E3 (X1 side) in the X-axis direction.

[0051] In other words, the electrode body 20 of the second embodiment is composed of a single base material 71 made up of a first base material and a second base material. A first metal layer 72 and a first composite layer 74 are formed on one side of the base material 71, and a second metal layer 73 and a second composite layer 75 are formed on the other side. In the positive and negative electrode plates 70, the first metal layer 72 has a first exposed portion E3 at one end in the X-axis direction (the end on the X1 side) where the first composite layer 74 is not formed (i.e., the first metal layer 72 is exposed). In the positive and negative electrode plates 70, the second metal layer 73 has a second exposed portion E4 at the other end in the X-axis direction (the end on the X2 side) where the second composite layer 75 is not formed (i.e., the second metal layer 73 is exposed). In addition, the length of the first exposed portion E3 decreases in the X-axis direction as it moves from one end (side of edge 70A) to the other end (side of edge 70B) in the longitudinal direction, and the length of the second exposed portion E4 decreases in the X-axis direction as it moves from the other end (side of edge 70B) to the one end (side of edge 70A) in the longitudinal direction.

[0052] Thus, as shown in Figure 9, the positive and negative electrode plates 70 have a first metal layer 72, a first exposed portion E3, and a first composite layer 74 on one side of the base material 71, and a second metal layer 73, a second exposed portion E4, and a second composite layer 75 on the other side of the base material 71. In the second embodiment, as shown in Figure 9, the electrode body 20 is formed by winding the positive and negative electrode plates 70 along the longitudinal direction of the positive and negative electrode plates 70 from the side of the edge portion 70B (see Figure 8) (see Figure 10) with the separator 60c placed on the first composite layer 74. As shown in Figure 10, the electrode body 20 of the second embodiment has a positive electrode terminal joint portion 21 with the first exposed portion E3 exposed on the X1 side and outer circumference of the electrode body 20, and a negative electrode terminal joint portion 22 with the second exposed portion E4 exposed on the X2 side and inner circumference of the electrode body 20. Figure 10 shows the electrode body 20 in its state after winding but before being formed into a flat shape.

[0053] Therefore, in the second embodiment, the positive electrode current collector 30a is connected to the first exposed portion E3 exposed on the outer circumference side of the electrode body 20, and the negative electrode current collector 31a is connected to the second exposed portion E4 exposed on the inner circumference side of the electrode body 20.

[0054] [Another embodiment] [1] In the above embodiment, the electrode body 20 was shown in which, in both the positive and negative electrodes, the length of the exposed portion of the metal layer decreases in the X-axis direction (winding axis direction) as it moves from one end to the other in the longitudinal direction, and the electrode plates (40, 50, 70) are exposed sequentially from one end in the longitudinal direction. Alternatively, the electrode body may be configured such that, in only one of the positive and negative electrodes, the length of the exposed portion of the metal layer decreases in the X-axis direction (winding axis direction) as it moves from one end to the other in the longitudinal direction, and the electrode plates (40, 50, 70) are exposed sequentially from one end in the longitudinal direction.

[0055] [2] In the above embodiment, an example was shown in which a metal layer (42A, 42B, etc.) was deposited onto a resin substrate (41, etc.) and then cut, but the resin substrate may be cut beforehand and then the metal layer may be deposited. In this way, the amount of metal used can be further reduced.

[0056] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Moreover, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention. [Explanation of Symbols]

[0057] 1: Secondary battery 10: Battery case 20: Electrode body 21:Positive electrode terminal joint (first electrode joint) 22:Negative electrode terminal joint (second electrode joint) 40: Positive electrode plate (first electrode plate) 41: 1st base material 42A, 42B: 1st metal layer 43A, 43B: First composite material layer (first active material layer) 50: Negative electrode plate (second electrode plate) 51:Second base material 52A, 52B: 2nd metal layer 53A, 53B: Second composite material layer (second active material layer) 60a, 60b, 60c: Separator 70:Positive and negative plates (1st plate, 2nd plate) 71: Base material 72: 1st metal layer 73: Second metal layer 74: First composite material layer (first active material layer) 75: Second composite material layer (second active material layer) PS: Positive battery terminal (1st battery terminal) NS: Negative battery terminal (second battery terminal) E1,E3: 1st exposed part E2,E4: 2nd exposed part X: Winding axis direction

Claims

1. An electrode body comprising a strip-shaped first electrode plate and a strip-shaped second electrode plate wound along the longitudinal direction with a separator in between, The first electrode plate comprises a first substrate made of resin, a first metal layer formed on the first substrate, and a first active material layer formed on the first metal layer. The first metal layer has a first exposed portion at one end in the winding axis direction of the electrode body, where the first active material layer is not formed. The length of the first exposed portion decreases in the winding axis direction as it moves from one end to the other end in the longitudinal direction. An electrode body having a first electrode junction formed in which the first exposed portion is exposed sequentially from one end in the longitudinal direction.

2. The aforementioned second electrode plate comprises a second substrate made of resin, a second metal layer formed on the second substrate, and a second active material layer formed on the second metal layer. The second metal layer has a second exposed portion at the other end in the winding axis direction where the second active material layer is not formed. The length of the second exposed portion decreases in the winding axis direction as it moves from one end to the other end, or from the other end to one end, in the longitudinal direction. The electrode body according to claim 1, wherein the second exposed portion is formed by a second electrode junction that is exposed sequentially from one end in the longitudinal direction or from the other end.

3. The first electrode plate has a first metal layer formed on the front and back surfaces of the first substrate, and a first active material layer formed on each of the first metal layers. The second electrode plate has the second metal layer formed on the front and back surfaces of the second substrate, and the second active material layer formed on each of the second metal layers. The electrode body according to claim 2, wherein the first electrode plate and the second electrode plate are wound together in a state where they are stacked on top of each other with the first active material layer and the second active material layer facing each other with the separator in between.

4. A single substrate is composed of the aforementioned first substrate and the aforementioned second substrate. The first metal layer and the first active material layer are formed on one side of the substrate, and the second metal layer and the second active material layer are formed on the other side. The electrode body according to claim 2, wherein the length of the second exposed portion decreases in the winding axis direction as it moves from the other end to the one end in the longitudinal direction.

5. Battery case and The electrode body housed in the aforementioned battery case, It comprises a first battery terminal electrically connected to the electrode body, The electrode body is A strip-shaped first electrode plate and a strip-shaped second electrode plate are wound together along the longitudinal direction with a separator in between. The first electrode plate comprises a first substrate made of resin, a first metal layer formed on the first substrate, and a first active material layer formed on the first metal layer. The first metal layer has a first exposed portion at one end in the winding axis direction of the electrode body, where the first active material layer is not formed. The length of the first exposed portion decreases in the winding axis direction as it moves from one end to the other end in the longitudinal direction. The first exposed portion is formed by exposing a first electrode joint portion sequentially from one end in the longitudinal direction, A secondary battery in which the first battery terminal is connected to the first electrode junction.

6. The electrode body further comprises a second battery terminal electrically connected to it. The aforementioned second electrode plate comprises a second substrate made of resin, a second metal layer formed on the second substrate, and a second active material layer formed on the second metal layer. The second metal layer has a second exposed portion at the other end in the winding axis direction where the second active material layer is not formed. The length of the second exposed portion decreases in the winding axis direction as it moves from one end to the other end, or from the other end to one end, in the longitudinal direction. The second exposed portion is formed by exposing the second electrode joint portion sequentially from one end in the longitudinal direction, or exposing it from the other end. The secondary battery according to claim 5, wherein the second battery terminal is joined to the second electrode junction.

7. The secondary battery according to claim 6, wherein the first electrode junction has a first exposed portion exposed on the outside of the electrode body, and the second electrode junction has a second exposed portion exposed on the outside of the electrode body.

8. A single substrate is composed of the aforementioned first substrate and the aforementioned second substrate. The first metal layer and the first active material layer are formed on one side of the substrate, and the second metal layer and the second active material layer are formed on the other side. The length of the second exposed portion decreases in the winding axis direction as it moves from the other end to the one end in the longitudinal direction. The secondary battery according to claim 6, wherein the first electrode junction has a first exposed portion exposed on the outside of the electrode body, and the second electrode junction has a second exposed portion exposed on the inside of the electrode body.

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