stacked battery

Abstract

To make it possible to increase a planar size of an electrode plate of a cell while suppressing increase in current deviation.SOLUTION: A laminated battery includes a cell laminate, a positive collector plate, a negative collector plate, a positive collector terminal, and a negative collector terminal. The cell laminate is formed by laminating a plurality of cells each having a positive electrode layer and a negative electrode layer of adjacent electrode plates which are configured to face each other through an electrolyte layer interposed therebetween. The positive electrode current collector plate includes a pair of positive electrode side protruding end portions which is formed so as to protrude to both end sides in a terminal arrangement direction with respect to a joint surface with the cell laminate. The negative electrode current collector plate includes a pair of negative electrode side protruding end portions which is formed so as to protrude to both end sides in the terminal arrangement direction with respect to the joint surface with the cell laminate. A cross-sectional area of the pair of positive electrode side protruding end portions in the terminal arrangement direction is larger than a cross-sectional area of the other portions of the positive electrode current collector plate in a same direction. A cross-sectional area of the pair of negative electrode side protruding end portions in the terminal arrangement direction is larger than a cross-sectional area of other portions of the negative electrode current collector plate in the same direction.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a stacked battery. [Background technology]

[0002] Patent Document 1 discloses a battery including an electrode plate assembly in which positive electrode plates, separators, and negative electrode plates are stacked. This battery is constructed by having the substrate end of at least one of the positive and negative electrode plates protrude from one surface of the electrode plate assembly, and welding the substrate end to comb teeth provided on a plate-shaped current collector terminal. The comb teeth of the plate-shaped current collector terminal and the current collector terminal body are separate parts, and the comb teeth are welded to the current collector terminal body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-175792 Summary of the Invention [Problem to be solved by the invention]

[0004] In bipolar or monopolar stacked batteries having a structure in which a cell stack is interposed between a positive current collector plate and a negative current collector plate, increasing the planar size of the cell's electrode plates to improve battery performance can lead to the following problem. As the planar size of the electrode plates increases, the planar sizes of the positive and negative current collector plates also increase. As a result, many areas on the planar surface of each current collector plate are farther from the current collector terminal. In areas farther from the current collector terminal, the length of the current path from the negative current collector terminal to the positive current collector terminal via the negative current collector plate, the cell stack, and the positive current collector increases. In other words, increasing the planar size of the electrode plates leads to a greater difference in the length of the current path between each area within the cell stack.

[0005] The shorter the current path, the lower the electrical resistance. Therefore, as the difference in current path length increases, the current flows more concentratedly through the short current path. In other words, the current deviation between each part inside the cell stack increases. The excessive current concentration caused by this increase in current deviation leads to a local increase in the temperature of the cell stack and accelerated deterioration.

[0006] The present disclosure has been made in consideration of the above-described problems, and aims to provide a stacked battery that enables the planar size of the cell electrode plates to be increased while suppressing an increase in current deviation. [Means for solving the problem]

[0007] The stacked battery according to the present disclosure includes a cell stack, a positive electrode current collector plate, a negative electrode current collector plate, a positive electrode current collector terminal, and a negative electrode current collector terminal. The cell stack is formed by stacking a plurality of cells, each configured such that the positive electrode layer and negative electrode layer of adjacent electrode plates face each other with an electrolyte layer interposed therebetween. The positive electrode current collector plate and the negative electrode current collector plate each have a planar shape and are arranged with the cell stack interposed therebetween. The positive electrode current collector terminal is provided on the positive electrode current collector plate at an end in the terminal arrangement direction, as viewed from the stacking direction of the cells. The negative electrode current collector terminal is provided on the negative electrode current collector plate at an end opposite the end on the side where the positive electrode current collector terminal is provided, as viewed from the stacking direction. The positive electrode current collector includes a pair of positive electrode-side protruding ends formed so as to protrude from both ends in the terminal arrangement direction relative to the joint surface with the cell stack, and the negative electrode current collector includes a pair of negative electrode-side protruding ends formed so as to protrude from both ends in the terminal arrangement direction relative to the joint surface with the cell stack. The cross-sectional areas of the pair of positive electrode protruding ends in the terminal arrangement direction are larger than the cross-sectional areas of other portions of the positive electrode current collector plate in the terminal arrangement direction, and the cross-sectional areas of the pair of negative electrode protruding ends in the terminal arrangement direction are larger than the cross-sectional areas of other portions of the negative electrode current collector plate in the terminal arrangement direction.

[0008] The pair of positive electrode side projecting end portions may have a folded-back shape at the end of the pair of positive electrode side projecting end portions, and the pair of negative electrode side projecting end portions may have a folded-back shape at the end of the pair of negative electrode side projecting end portions.

[0009] The pair of positive electrode side protruding ends may be formed by joining a separate plate to the positive electrode current collector plate, and the pair of negative electrode side protruding ends may be formed by joining a separate plate to the negative electrode current collector plate.

[0010] The pair of positive electrode-side projecting ends may be formed integrally with other portions of the positive electrode current collector so that the thickness of the pair of positive electrode-side projecting ends in the stacking direction is greater than the thickness of other portions of the positive electrode current collector in the stacking direction, and the pair of negative electrode-side projecting ends may be formed integrally with other portions of the negative electrode current collector so that the thickness of the pair of negative electrode-side projecting ends in the stacking direction is greater than the thickness of other portions of the negative electrode current collector in the stacking direction. [Effects of the Invention]

[0011] According to the stacked battery of the present disclosure, by providing the positive electrode protruding end portion and the negative electrode protruding end portion having the above-described configuration, each of the positive electrode current collector plate and the negative electrode current collector plate can have a structure in which the electrical resistance at both ends in the terminal arrangement direction is lower than at other portions. In other words, a structure is obtained in which current flows more easily through each of the positive electrode protruding end portion and the negative electrode protruding end portion. As a result, the current can be dispersed throughout the positive electrode current collector plate and the negative electrode current collector plate. In other words, the above-mentioned current deviation can be reduced. By providing such a current collection structure for the positive electrode current collector plate and the negative electrode current collector plate, it is possible to provide a stacked battery that allows the planar size of the cell electrode plates to be increased while suppressing an increase in current deviation. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an exploded perspective view schematically showing an example of the basic configuration of a stacked bipolar battery according to a first embodiment. [Figure 2] 2 is a cross-sectional view schematically showing an example of the structure of the cell stack shown in FIG. 1. FIG. [Figure 3] 2 is a view of the stacked bipolar battery shown in FIG. 1 as seen from the stacking direction D1 of the cells in the cell stack. [Figure 4] FIG. 2 is a diagram illustrating the configuration of a stacked bipolar battery according to a comparative example, which is referred to for comparison with the stacked bipolar battery of the first embodiment. [Figure 5] 4 is a cross-sectional view of the cell stack, the positive electrode current collector plate, and the negative electrode current collector plate taken along line AA in FIG. 3. FIG. [Figure 6] 5A and 5B are diagrams for explaining the effect of the current collecting structure of the stacked bipolar battery according to the first embodiment. [Figure 7] FIG. 10 is a cross-sectional view illustrating the configuration of a stacked bipolar battery according to a second embodiment. [Figure 8] FIG. 10 is a cross-sectional view illustrating the configuration of a stacked bipolar battery according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] In the embodiments described below, elements common to each drawing are assigned the same reference numerals, and redundant explanations are omitted or simplified. Furthermore, when the number, quantity, amount, range, etc. of each element is mentioned in the embodiments described below, the technical idea of the present disclosure is not limited to the mentioned number unless otherwise specified or clearly specified in principle. Furthermore, the structures, etc. described in the embodiments described below are not necessarily essential to the technical idea of the present disclosure unless otherwise specified or clearly specified in principle.

[0014] 1. First Embodiment 1-1. Basic configuration example of a stacked bipolar battery FIG. 1 is an exploded perspective view schematically illustrating an example of the basic configuration of a stacked bipolar battery 10 according to a first embodiment. The stacked bipolar battery 10 (hereinafter also simply referred to as "battery 10") has a substantially rectangular parallelepiped shape. The battery 10 is typically a rechargeable secondary battery. The battery 10 includes a cell stack 12, a positive electrode current collector plate 14, a negative electrode current collector plate 16, a positive electrode current collector terminal 18, and a negative electrode current collector terminal 20.

[0015] In the example shown in FIG. 1 , a battery 10 includes a plurality of stacked cell stacks 12. As shown in FIG. 1 , the positive electrode current collector 14 and the negative electrode current collector 16 each have a planar shape. The positive electrode current collector 14 and the negative electrode current collector 16 are arranged so as to sandwich the plurality of cell stacks 12 therebetween. The number of cell stacks 12 arranged between the positive electrode current collector 14 and the negative electrode current collector 16 is not particularly limited and may be one. In the example shown in FIG. 1 , the cell stacks 12 are alternately stacked with cooling plates 22 for cooling the cell stacks 12. The cooling plates 22 are made of a metal such as aluminum or copper, and electrically connect adjacent cell stacks 12 in series.

[0016] 2 is a cross-sectional view schematically illustrating an example of the structure of the cell stack 12 shown in FIG. 1. The cell stack 12 is configured by stacking a plurality of cells 24 in one direction. Each cell 24 is configured so that the positive electrode layer 28 and the negative electrode layer 30 of adjacent bipolar electrode plates 26 face each other with a separator (electrolyte layer) 32 interposed therebetween. The vertical direction of the paper in FIG. 2 corresponds to the "stacking direction D1" of the cells 24. The stacking direction D1 is also parallel to the vertical direction of the paper in FIG. 1.

[0017] More specifically, the cell stack 12 includes a frame 34 along with a plurality of bipolar electrode plates 26 and a plurality of separators 32. The bipolar electrode plates 26 are supported by the frame 34 so as to be spaced apart in the stacking direction D1. The separators 32 are disposed between adjacent bipolar electrode plates 26.

[0018] Each bipolar electrode plate 26 includes an electrode plate portion 36, a positive electrode layer 28, and a negative electrode layer 30. The electrode plate portion 36 is formed of a metal material such as nickel. The positive electrode layer 28 includes a positive electrode active material. For example, nickel hydroxide is used as the positive electrode active material. The negative electrode layer 30 includes a negative electrode active material. For example, a hydrogen-absorbing alloy is used as the negative electrode active material. As shown in FIG. 2, only one of the positive electrode layer 28 and the negative electrode layer 30 is formed on the electrode plate portions 36 located at both ends in the stacking direction D1. The separator 32 is formed in a sheet shape. For example, the separator 32 is formed using a porous film formed from a polyolefin resin.

[0019] Within the cell stack 12 configured as described above, an accommodation space 38 is formed by adjacent electrode plate portions 36 and frame bodies 34. Separators 32, positive electrode layers 28, negative electrode layers 30, and an electrolyte (not shown) are disposed within this accommodation space 38. The electrolyte is, for example, an alkaline solution such as an aqueous potassium hydroxide solution. The separators 32, negative electrode layers 30, positive electrode layers 28, and the electrolyte form a cell 24. A plurality of cells 24 are arranged in the stacking direction D1. The cells 24 are connected in series by the electrode plate portions 36. During discharge of the battery 10, current flows within the cell stack 12 from the upper side (negative electrode current collector 16 side) to the lower side (positive electrode current collector 14 side) in FIG. 2 .

[0020] 3 is a view of the battery 10 shown in FIG. 1 as viewed from the stacking direction D1 of the cells 24 in the cell stack 12. In other words, FIG. 3 corresponds to a view of the battery 10 as viewed from above on the paper in FIG. 1. Therefore, the positive current collector 14 overlaps with and is hidden by the negative current collector 16.

[0021] 3, i.e., the direction parallel to one side 16a of the rectangular negative current collector plate 16 when viewed from the stacking direction D1, is referred to as the "terminal arrangement direction D2." The positive current collector terminal 18 and the negative current collector terminal 20 are provided on the same side of the cell stack 12 (the side of the one side 16a of the negative current collector plate 16 in FIG. 3). These current collector terminals (e.g., current collector tabs) 18 and 20 are provided to extract power generated by the battery 10 to the outside.

[0022] 3 (i.e., when viewed from the stacking direction D1), the positive electrode collector terminal 18 is provided on the positive electrode collector plate 14 at an end 14a in the terminal arrangement direction D2. On the other hand, the negative electrode collector terminal 20 is provided on the negative electrode collector plate 16 at an end 16c opposite to the end 16b on the side where the positive electrode collector terminal 18 is provided in the terminal arrangement direction D2, when viewed from the stacking direction D1.

[0023] 1-2.Comparative example Fig. 4 is a diagram illustrating the configuration of a stacked bipolar battery 100 according to a comparative example, which is referred to for comparison with the battery 10 according to embodiment 1. Fig. 4 is a view of the battery 100 viewed from the same direction as Fig. 3. The battery 100 according to the comparative example differs from the battery 10 according to embodiment 1 in the configuration of the positive and negative current collector plates.

[0024] The positive current collector 102 and the negative current collector 104 included in the battery 100 have a typical shape. Specifically, as shown in FIG. 4 (viewed from the stacking direction D1), the positive current collector 102 and the negative current collector 104 are formed to have the same size as the cell stack 12. In addition, the size of interest here is the size in the terminal arrangement direction D2. The width of each of the positive current collector 102 and the negative current collector 104 in the terminal arrangement direction D2 is the same as that of the cell stack 12.

[0025] In the comparative battery 100 having the above-described configuration, increasing the planar size of the bipolar electrode plate 26 (more specifically, increasing the size in the horizontal and vertical directions in FIG. 4 ) to improve battery performance results in the following problem. Specifically, as the planar size of the bipolar electrode plate 26 increases, the planar sizes of the positive current collector plate 102 and the negative current collector plate 104 also increase. As a result, the distance between the current collector terminals 18 and 20 increases in many areas on the planar surfaces of the current collector plates 102 and 104. In areas far from the current collector terminals 18 and 20, the length of the current path (see the arrows in FIG. 4 ) from the negative current collector terminal 20 to the positive current collector terminal 18 via the negative current collector plate 104, the cell stack 12, and the positive current collector plate 102 increases. In other words, increasing the planar size of the bipolar electrode plate 26 leads to an increase in the difference in the length of the current path between various areas within the cell stack 12.

[0026] In Figure 4, the thickness of the arrows indicates the magnitude of the current flowing through each illustrated current path. The shorter the current path, the lower the electrical resistance. Therefore, as the difference in current path length increases, the current flows more concentratedly through the short current path. In other words, the current deviation between various parts inside the cell stack 12 increases. The excessive current concentration caused by this increase in current deviation leads to a local increase in the temperature of the cell stack 12.

[0027] 1-3. Characteristic current collection structure of embodiment 1 In consideration of the above-described problems explained with reference to the comparative example, the battery 10 of this embodiment has the following characteristic current collecting structure. Here, reference is made to FIG. 5 in addition to the above-described FIG. 3. FIG. 5 is a cross-sectional view of the cell stack 12, the positive electrode current collector 14, and the negative electrode current collector 16 taken along line AA in FIG. 3.

[0028] The positive current collector 14 includes a pair of positive electrode side protruding ends 14d formed to protrude from both ends in the terminal arrangement direction D2 relative to the joint surface 40 with the cell stack 12. Similarly, the negative current collector 16 includes a pair of negative electrode side protruding ends 16d formed to protrude from both ends in the terminal arrangement direction D2 relative to the joint surface 42 with the cell stack 12.

[0029] 5, the cross-sectional area of the positive electrode-side protruding end 14d in the terminal arrangement direction D2 is larger than the cross-sectional area of other parts of the positive electrode current collector 14 in the same direction D2 (i.e., parts other than the positive electrode-side protruding end 14d). Similarly, the cross-sectional area of the negative electrode-side protruding end 16d in the terminal arrangement direction D2 is larger than the cross-sectional area of other parts of the negative electrode current collector 16 in the same direction D2.

[0030] More specifically, in the first embodiment, the positive electrode side projecting end 14d has a folded shape 14d1 at its end, so that the cross-sectional area of the positive electrode side projecting end 14d in the terminal arrangement direction D2 is larger than the cross-sectional area of the other portions. Similarly, the negative electrode side projecting end 16d has a folded shape 16d1 at its end, so that the cross-sectional area of the negative electrode side projecting end 16d in the terminal arrangement direction D2 is larger than the cross-sectional area of the other portions. The folded shape 14d1 can be formed, for example, by bending the end of the positive electrode side projecting end 14d. The same applies to the folded shape 16d1.

[0031] 1-4.Effects FIG. 6 is a diagram illustrating the effect of the current collecting structure of the battery 10 according to the first embodiment. FIG. 6 is a view of the battery 10 viewed from the same direction as FIG. 3. As described above, the current collector plates 14 and 16 of the battery 10 include the positive electrode-side protruding end portion 14d and the negative electrode-side protruding end portion 16d, which have larger cross-sectional areas than the other portions. Therefore, each of the current collector plates 14 and 16 can have a structure in which the electrical resistance at both ends in the terminal arrangement direction D2 is lower than that of the other portions. In other words, a structure is obtained in which current flows more easily through the positive electrode-side protruding end portion 14d and the negative electrode-side protruding end portion 16d. As a result, as indicated by the arrows in FIG. 6, current can be dispersed throughout the current collector plates 14 and 16 compared to the comparative example shown in FIG. 4. In other words, the current deviation can be reduced (excessive current concentration can be suppressed), thereby suppressing local increases in temperature of the cell stack 12.

[0032] As described above, the current collection structure of this embodiment makes it possible to provide a stacked bipolar battery 10 that allows the planar size of the bipolar electrode plate 26 to be increased while suppressing an increase in current deviation.

[0033] 2. Second Embodiment Fig. 7 is a cross-sectional view illustrating the configuration of a stacked bipolar battery 50 according to embodiment 2. Fig. 7 shows a cross-sectional view similar to Fig. 5. The battery 50 according to embodiment 2 differs from the battery 10 according to embodiment 1 in the configuration of the current collector plates.

[0034] Specifically, in this embodiment, in order to make the cross-sectional area of the pair of positive electrode side protruding ends 52d of the positive electrode current collector 52 in the terminal arrangement direction D2 larger than the cross-sectional area of other portions in the same direction D2, the pair of positive electrode side protruding ends 52d are formed by joining a separate plate 54 to the main body of the positive electrode current collector 52. The plate 54 is made of the same metal material as the positive electrode current collector 52. The positive electrode current collector 52 and the plate 54 can be joined together by, for example, welding or adhesive bonding.

[0035] Similar to the pair of positive electrode side protruding ends 52d described above, the pair of negative electrode side protruding ends 56d are formed by joining a separate plate 58 to the main body of the negative electrode current collector 56 so that the cross-sectional area of the pair of negative electrode side protruding ends 56d of the negative electrode current collector 56 in the terminal arrangement direction D2 is larger than the cross-sectional area of other portions in the same direction D2.

[0036] The current collection structure of the second embodiment described above also makes it possible to provide a stacked bipolar battery 50 that allows the planar size of the bipolar electrode plate 26 to be increased while suppressing an increase in current deviation.

[0037] 3. Embodiment 3 Fig. 8 is a cross-sectional view illustrating the configuration of a stacked bipolar battery 60 according to embodiment 3. Fig. 8 shows a cross-sectional view similar to Fig. 5. The battery 60 according to embodiment 3 differs from the battery 10 according to embodiment 1 in the configuration of the current collector plates.

[0038] Specifically, in this embodiment, the pair of positive electrode side protruding ends 62d of the positive electrode current collector 62 in the terminal arrangement direction D2 are formed integrally with other portions so that the thickness of the pair of positive electrode side protruding ends 62d in the stacking direction D1 is greater than the thickness of the other portions of the positive electrode current collector 62. Such a pair of positive electrode side protruding ends 62d can be formed by, for example, using an extrusion process.

[0039] Similar to the pair of positive electrode side protruding ends 62d described above, the pair of negative electrode side protruding ends 64d of the negative electrode current collector 64 in the terminal arrangement direction D2 are formed integrally with the other portions so that the thickness of the pair of negative electrode side protruding ends 64d in the stacking direction D1 is greater than the thickness of the other portions of the negative electrode current collector 64.

[0040] The current collection structure of the third embodiment described above also makes it possible to provide a stacked bipolar battery 60 that allows the planar size of the bipolar electrode plate 26 to be increased while suppressing an increase in current deviation.

[0041] In the above-described first embodiment and the like, the separator 32 impregnated with an electrolytic solution is exemplified as the "electrolyte layer." However, the "electrolyte layer" according to the present disclosure may be, for example, a solid electrolyte or a gel electrolyte. Furthermore, in the above-described first embodiment and the like, the stacked bipolar batteries 10, 50, and 60 are exemplified. However, the "stacked battery" according to the present disclosure is not limited to a bipolar type and may be a monopolar type. In other words, the "cell stack" according to the present disclosure may be formed by stacking multiple cells, each configured such that the positive electrode layer of one of the "adjacent electrode plates" faces the negative electrode layer of the other of the "adjacent electrode plates" via an electrolyte layer. [Explanation of symbols]

[0042] 10, 50, 60 stacked bipolar battery 12 Cell stack 14, 52, 62 Positive current collector plate 14d, 52d, 62d Positive side protruding end 14d1 Folded shape of the protruding end on the positive electrode side 16, 56, 64 Negative current collector plate 16d, 56d, 64d Negative side protruding end 16d1 Folded shape of the protruding end on the negative electrode side 18 Positive current collecting terminal 20 Negative electrode current collecting terminal 24 cells 26 Bipolar electrode plate 28 Positive electrode layer of bipolar electrode plate 30 Negative electrode layer of bipolar electrode plate 32 Separator 34 Frame 36 Electrode plate portion of bipolar electrode plate 38 Cell stack internal storage space 40, 42 Cell joint surface 54, 58 board

Claims

1. a cell stack formed by stacking a plurality of cells configured such that the positive electrode layer and the negative electrode layer of adjacent electrode plates face each other via an electrolyte layer; a positive electrode current collector plate and a negative electrode current collector plate each having a planar shape and arranged so as to sandwich the cell stack; a positive electrode current collector terminal provided on the positive electrode current collector plate at an end in a terminal arrangement direction when viewed from the stacking direction of the cells; a negative electrode current collector terminal provided on the negative electrode current collector plate at an end opposite to an end on which the positive electrode current collector terminal is provided in the terminal arrangement direction, as viewed from the stacking direction; Equipped with the positive electrode current collector plate includes a pair of positive electrode side protruding end portions formed so as to protrude from both end sides in the terminal arrangement direction relative to a positive electrode side joint surface with the cell stack, the negative electrode current collector plate includes a pair of negative electrode-side protruding end portions formed so as to protrude from both end sides in the terminal arrangement direction relative to a negative electrode-side joint surface with the cell stack, a cross-sectional area of each of the pair of positive electrode side protruding ends in the terminal arrangement direction is larger than a cross-sectional area of other portions of the positive electrode current collector plate in the terminal arrangement direction, a cross-sectional area of each of the pair of negative electrode side protruding ends in the terminal arrangement direction is larger than a cross-sectional area of other portions of the negative electrode current collector plate in the terminal arrangement direction, the positive electrode current collector plate does not protrude from the positive electrode-side joint surface at both ends in a direction perpendicular to the terminal arrangement direction when viewed from the stacking direction, The negative electrode current collector plate does not protrude from the negative electrode side joint surface at both ends in the direction perpendicular to the terminal arrangement direction when viewed from the stacking direction. A stacked battery characterized by:

2. The pair of positive electrode side protruding end portions have a folded shape at the ends of the pair of positive electrode side protruding end portions, The pair of negative electrode side protruding end portions have a folded shape at the end of the pair of negative electrode side protruding end portions.

2. The stacked battery according to claim 1 .

3. the pair of positive electrode side protruding end portions are formed by joining separate plates to the positive electrode current collector plate, The pair of negative electrode side protruding ends are formed by joining a separate plate to the negative electrode current collector plate.

2. The stacked battery according to claim 1 .

4. the pair of positive electrode side protruding end portions are formed integrally with the other portions of the positive electrode current collector plate such that a thickness of the pair of positive electrode side protruding end portions in the stacking direction is greater than a thickness of the other portions of the positive electrode current collector plate in the stacking direction, The pair of negative electrode side protruding end portions are formed integrally with the other portions of the negative electrode current collector plate such that the thickness of the pair of negative electrode side protruding end portions in the stacking direction is greater than the thickness of the other portions of the negative electrode current collector plate in the stacking direction.

2. The stacked battery according to claim 1 .

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