Secondary batteries

Abstract

To suppress the expansion of an electrode body, thereby suppressing leakage of an electrolyte to the outside of the electrode body.SOLUTION: A secondary battery is a laminated or rectangular secondary battery, and includes an electrode body, an outer container, and a first fixing member. The electrode body is a laminated or wound electrode body having a flat shape. The outer container houses the electrode body impregnated with an electrolyte. The first fixing member is provided along a target side, which is at least one side of the electrode body having a rectangular shape when viewed in the thickness direction of the electrode body. The first fixing member fixes a target end, which is an end of the electrode body corresponding to the target side, over a length range of at least one fourth of the length of the target side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laminate-type or prismatic secondary battery. [Background Art]

[0002] Patent Document 1 discloses a battery. This battery includes a regulating member that regulates the approach and separation of the negative electrode and the positive electrode in the stacking direction of the battery element (electrode assembly) during charge and discharge. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2003-123843 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In a secondary battery including a stacked or wound electrode assembly impregnated with an electrolytic solution, when the electrode assembly expands, the electrolytic solution may leak out of the electrode assembly.

[0005] The present disclosure has been made in view of the problems described above, and an object of the present disclosure is to provide a secondary battery capable of suppressing expansion of an electrode assembly and suppressing leakage of an electrolytic solution to the outside of the electrode assembly. [Means for Solving the Problem]

[0006] A secondary battery according to the present disclosure is a laminate-type or prismatic secondary battery, including an electrode assembly, an outer casing container, and a first fixing member. The electrode assembly is a stacked or wound electrode assembly having a flat shape. The outer casing container houses the electrode assembly impregnated with an electrolytic solution. The first fixing member is provided along a target side that is at least one side of the electrode assembly having a rectangular shape when viewed from the thickness direction of the electrode assembly. The first fixing member fixes a target end portion, which is an end portion of the electrode assembly corresponding to the target side, over a length range of 1 / 4 or more of the length of the target side. [Effects of the Invention]

[0007] According to this disclosure, by providing the above-described first fixing member, it is possible to suppress the expansion of the electrode body and prevent the electrolyte from leaking out of the electrode body. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows an example of the configuration of a secondary battery according to Embodiment 1. [Figure 2] This figure schematically shows another example of the configuration of the secondary battery according to Embodiment 1. [Figure 3] This diagram schematically shows an example of the configuration of a secondary battery according to Embodiment 2. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described with reference to the attached drawings. In each drawing, elements common to all figures are denoted by the same reference numerals, and redundant explanations are omitted or simplified.

[0010] 1. Embodiment 1 Figure 1 is a schematic diagram showing an example of the configuration of a secondary battery according to Embodiment 1. The secondary battery 10 shown in Figure 1 comprises an electrode body 11, an outer casing 12, a pair of electrode terminals 13, and adhesive tapes 14 and 15.

[0011] In Embodiment 1, the electrode body 11 is a flattened, laminated electrode body (laminated). The electrode body 11 is constructed by alternately stacking, for example, a plurality of positive electrode plates and a plurality of negative electrode plates in the thickness direction of the electrode body 11 with separators in between. Figure 1 is a view of the electrode body 11 from the thickness direction. When viewed from the thickness direction, the electrode body 11 has a rectangular shape as shown in Figure 1. The outer container 12 houses the electrode body 11 impregnated with electrolyte. A pair of electrode terminals 13 are connected to tabs on the positive electrode plate and the negative electrode plate, respectively.

[0012] 1-1. Structure of the adhesive tape (first fixing member) The adhesive tape 14 corresponds to an example of the "first fixing member" according to this disclosure. The adhesive tape 14 is provided along the "target side TS" of the electrode body 11, which has a rectangular shape when viewed from the thickness direction, as shown in Figure 1. In the example shown in Figure 1, the two sides S1 and S2 located at each end of the longitudinal direction D1 of the electrode body 11 correspond to the target side TS. In other examples, the number of target sides TS may be one, three, or four. In addition, the first fixing member (and the second fixing member described later) is not limited to adhesive tape, as long as it has adhesive strength and is resistant to electrolyte.

[0013] The adhesive tape 14 is provided to cover the "target end TE," which is the end of the electrode body 11 corresponding to the target side TS, and to fix the target end TE. In the example shown in Figure 1, the two ends E1 and E2 corresponding to the two sides S1 and S2 correspond to the target end TE. As illustrated in Figure 1, the adhesive tape 14 fixes the target end TE over a length range of at least 1 / 4 of the length of the target side TS (the two sides S1 and S2). That is, the length of the adhesive tape 14 in the direction along the target side TS only needs to be at least 1 / 4 of the length of the target side TS. For example, the adhesive tape 14 may extend in the longitudinal direction of the target side TS so as to fix a length range corresponding to the entire length of the target side TS.

[0014] The secondary battery 10 may be of the laminated or rectangular type. More specifically, Figure 1 shows an example of a laminated secondary battery 10, in which the electrode body 11 is housed in a pair of flexible films that serve as an outer casing 12. As an example, the adhesive tape 14 is provided so as to extend not only to the target ends TE of the electrode body 11 (each of the two ends E1 and E2) but also to one of the components of the outer casing 12 located below the electrode body 11 (i.e., one of the pair of flexible films). In addition, in this example, the adhesive tape 14 is applied with the electrode body 11 placed on that one of the flexible films. The electrode body 11 is then covered by the other flexible film, and three sides of the pair of flexible films are bonded together. After the electrolyte is injected into the pair of flexible films, the remaining side of the pair of flexible films is sealed.

[0015] As shown in Figure 1, the ends E1 and E2 of the electrode body 11, which is impregnated with electrolyte, are fixed to the target end TE by adhesive tape 14. By fixing the target end TE with adhesive tape 14 in this way, expansion of the electrode body 11 at the target end TE is suppressed. As a result, leakage of electrolyte from inside the electrode body 11 can be suppressed. Through diligent research by the inventors, it has been found that a high level of effectiveness in suppressing electrolyte leakage can be obtained when the length of the adhesive tape 14 is 1 / 4 or more of the length of the target side TS. Therefore, the secondary battery 10 can effectively suppress leakage of electrolyte from inside the electrode body 11. As a result, the increase in the rate of resistance increase over time caused by repeated charging and discharging of the secondary battery 10 can be suppressed.

[0016] Furthermore, the inclusion of the adhesive tape 14 provides the following benefits: namely, it can suppress misalignment of the stacked electrode bodies 11 during use of the secondary battery 10. By suppressing the expansion of the electrode bodies 11, leakage of the electrode bodies 11 to the outside of the electrode bodies 11 can be suppressed, thereby improving the high-rate resistance of the secondary battery 10. In addition, since this measure involves adding and wrapping the adhesive tape 14, fewer additional components are required.

[0017] Alternatively, the secondary battery 10 may be configured as a prismatic battery using a case made of metal, resin, or the like as the outer container 12. When the secondary battery 10 is prismatic, the adhesive tape 14 may be provided inside the case on the target end portions TE (each of the two end portions E1 and E2) of the electrode assembly 11 in the same manner as the example shown in FIG. 1, for example. This provides the same effects as those obtained in the above-described laminated-type example. In addition, in the laminated type, the outer container 12 does not exert a binding force on the electrode assembly 11. Therefore, the effect obtained by providing the adhesive tape 14 is more favorably achieved in the laminated type than in the prismatic type. This also applies to the adhesive tape 15 (second fixing member) described later.

[0018] In addition, when the material of the adhesive tape 14 has a property of not allowing an electrolytic solution to permeate therethrough, if the width of the adhesive tape 14 is excessively large, the impregnation of the electrolytic solution is affected. Therefore, in this case, the width may be defined in consideration of the influence on the impregnation of the electrolytic solution. This also applies to the adhesive tape 15 (second fixing member) described later.

[0019] 1-2. Configuration of Adhesive Tape (Second Fixing Member) The adhesive tape 15 corresponds to an example of the "second fixing member" according to the present disclosure. As shown in FIG. 1, the adhesive tape 15 is provided at a central position P1 in the longitudinal direction D1 of the electrode assembly 11, and at positions P2 and P3 close to respective ends in the longitudinal direction D1 with respect to the central position P1. At each of the central position P1 and the positions P2 and P3, the adhesive tape 15 is wound around the electrode assembly 11 for one full turn or a longer length along a winding direction D2 orthogonal to the longitudinal direction D1. The adhesive tape 15 at the central position P1 is wound around the electrode assembly 11 with a higher tension than the adhesive tapes 15 at the positions P2 and P3, respectively.

[0020] In addition, the winding start portion and the winding end portion of the adhesive tape 15 are preferably provided at locations excluding the R portions and edge portions of the electrode body 11. Further, when the adhesive tape 15 is wound longer than one turn, the length of the portion where the adhesive tape 15 overlaps at the winding end position is preferably 1 / 50 or more of the length of the sides S1 and S2 along the winding direction D2.

[0021] Gas generated due to film formation accompanying electrolyte decomposition on an electrode (positive electrode, negative electrode) tends to accumulate in the central portion of the electrode body 11 (that is, the portion including the central position P1). As a result, the central portion is prone to expansion. More specifically, as the secondary battery 10 increases in size and the difference in the aspect ratio of the surface occupying a large area of the secondary battery 10 (the surface shown in FIG. 1) becomes larger, the central portion becomes more prone to expansion. In this regard, according to the configuration of the adhesive tape 15 described above, by making the tension of the adhesive tape 15 larger at the central position P1 than at other positions P2 and P3, it is possible to achieve a configuration in which the gas is easily moved from the center to the end and pushed out of the electrode body 11. As a result, expansion of the central portion, which is prone to expansion as described above, can be effectively suppressed. More specifically, time-dependent expansion (increase in the rate of increase in thickness) of the central portion caused by repeated charging and discharging of the secondary battery 10 can be suppressed.

[0022] Furthermore, the provision of the adhesive tape 15 also provides the following effects. That is, it is possible to suppress lamination misalignment of the stacked electrode body 11 during use of the secondary battery 10. Further, by suppressing expansion of the electrode body 11, leakage of the electrode body 11 out of the electrode body 11 can be suppressed, thereby improving the high-rate resistance of the secondary battery 10. In addition, since the countermeasure is to additionally wind the adhesive tape 15, only a small number of additional members are required.

[0023] In addition, in the example shown in Figure 1, the adhesive tape 15 is provided at two positions P2 and P3 in addition to the central position P1. As another example, the adhesive tape 15 may be provided at three or more positions near any end of the electrode body 11 in the longitudinal direction D1, in addition to the central position P1, while taking care not to affect the impregnation of the electrolyte. Also, in the example shown in Figure 1, the longitudinal direction D1 corresponds to the "specific direction" in this disclosure, and therefore the winding direction D2 of the adhesive tape 15 is perpendicular to the longitudinal direction D1. This effectively suppresses the expansion of the electrode body 11. However, the "specific direction" in this disclosure may be the short direction (i.e., the direction perpendicular to the longitudinal direction D1 in Figure 1 (up and down direction of the paper)). Therefore, the winding direction D2 may be perpendicular to the short direction.

[0024] 1-3. Other examples of placement locations for adhesive tape (first fixing member) Figure 2 is a schematic diagram showing another example of the configuration of the secondary battery according to Embodiment 1. The secondary battery 20 shown in Figure 2 is a stacked type, similar to the secondary battery 10, but differs from the secondary battery 10 in the placement of the "first fixing member". The secondary battery 30 may be either a laminated type or a rectangular type.

[0025] Specifically, in Figure 2, the upper and lower sides of the paper correspond to the upper and lower sides of the vertical direction D3, respectively. In this example, the lower end E3 and upper end E4 of the electrode body 11, which are located on the lower and upper sides respectively when the secondary battery 20 is mounted on the vehicle, correspond to the target end TE.

[0026] In the example shown in Figure 2, the adhesive tape 21, which serves as the first fixing member, is provided on both the lower end E3 and E4. The length of these adhesive tapes 21 is also at least 1 / 4 of the length of the target side TS. Furthermore, the length of the adhesive tape 21 fixing the lower end E3 in the direction of the target side TS (side S3) is greater than the length of the adhesive tape 21 fixing the upper end E4 in the direction of the target side TS (side S4).

[0027] As shown in Figure 2, the presence of adhesive tape 21 suppresses the expansion of the electrode body 11 and prevents electrolyte leakage from inside the electrode body 11. However, a longer adhesive tape 21 is a cost-increasing factor for the secondary battery 30. In the example of the secondary battery 30, as described above, when mounted, the adhesive tape 21 on the lower side in the vertical direction D3 is longer than the adhesive tape 21 on the upper side in the same direction D3. This effectively suppresses electrolyte leakage from the lower end E3, which is prone to leakage due to gravity, while taking into consideration the cost associated with the arrangement of the adhesive tape 21.

[0028] 2. Embodiment 2 Figure 3 is a schematic diagram showing an example of the configuration of a secondary battery according to Embodiment 2. The secondary battery 30 shown in Figure 3 is equipped with a wound electrode body 31 (wound body). That is, the electrode body 31 is equipped with a positive electrode body and a negative electrode body arranged via a separator, and is formed by winding them in a flattened shape along the winding direction D4 shown in Figure 3. Reference numeral 32 indicates the outer peripheral end of the wound electrode body 11. The electrode body 31 includes a pair of current collector plates 33 located at each end in the longitudinal direction D1 (winding axis direction). A pair of electrode terminals 34 are connected to the pair of current collector plates 33. The secondary battery 30 is, for example, rectangular, but may also be laminated. Similar to Figures 1 and 2, Figure 3 is a view of the electrode body 31 from the thickness direction.

[0029] In the example shown in Figure 3, the ends E5 and E6 of the electrode body 31 in the longitudinal direction D1 correspond to the target ends TE. That is, in this example, the target ends TE correspond to two target sides TS (sides S5 and S6) that are parallel to the winding direction D4 of the electrode body 31 when viewed from the thickness direction of the electrode body 31, as shown in Figure 3. The adhesive tape 35, which serves as the first fixing member, is provided on each of the two ends E5 and E6. The length of these adhesive tapes 35 is also at least 1 / 4 of the length of the target sides TS (sides S5 and S6).

[0030] According to the configuration shown in Figure 3, the inclusion of the adhesive tape 35 effectively suppresses leakage of electrolyte from each end of the electrode body 31 in the longitudinal direction D1 perpendicular to the winding direction D4.

[0031] Alternatively, instead of the example shown in Figure 3, the adhesive tape 35 may be provided on only one of the two symmetrical sides TS (sides S5 and S6) parallel to the winding direction D4 of the electrode body 31.

[0032] The secondary batteries 10, 20, and 30 according to the above-described embodiments 1 and 2 are each equipped with an adhesive tape 15 (second fixing member). Therefore, with any of the secondary batteries 10, 20, and 30, the combination of the first and second fixing members effectively suppresses the expansion of the electrode body 11 or 31 and effectively prevents electrolyte leakage. However, the "secondary battery" according to this disclosure may be equipped with only the first fixing member and without the second fixing member. [Explanation of Symbols]

[0033] 10, 20, 30 Secondary battery, 11, 31 Electrode body, 12 Outer casing, 13, 34 Pair of electrode terminals, 14, 21, 35 Adhesive tape (first fixing member), 15 Adhesive tape (second fixing member), 33 Pair of current collector plates

Claims

1. A laminated or rectangular rechargeable battery, A stacked electrode body having a flattened shape, An outer container for housing the electrode body impregnated with electrolyte, A first fixing member is provided along a target side which is at least one side of the electrode body having a rectangular shape when viewed from the thickness direction of the electrode body, Equipped with, The first fixing member covers a length range of 1 / 4 or more of the length of the target side, and fixes the target end, which is the end of the electrode body corresponding to the target side. The target end includes the lower end and the upper end, which are located on the lower and upper sides in the vertical direction when the secondary battery is mounted on the vehicle. The length of the first fixing member that secures the lower end in the direction of the target side is greater than the length of the first fixing member that secures the upper end in the direction of the target side. A secondary battery characterized by the following features.

2. A secondary battery according to claim 1, The electrode body further comprises a second fixing member provided at the central position in a specific direction, which is either the longitudinal or transverse direction, and at least two positions close to either end of the specific direction relative to the central position. The second fixing member is wrapped around the electrode body for a length of one or more turns along a winding direction perpendicular to the specific direction at the central position and at least two of the other positions. The tension of the second fixing member wrapped around the central position is greater than the tension of the second fixing member wrapped around each of the at least two positions. A secondary battery characterized by the following features.

3. A laminated or rectangular secondary battery, A laminated or wound electrode body having a flattened shape, An outer container for housing the electrode body impregnated with electrolyte, A first fixing member is provided along a target side which is at least one side of the electrode body having a rectangular shape when viewed from the thickness direction of the electrode body, A second fixing member is provided at the central position in a specific direction which is the longitudinal or transverse direction of the electrode body, and at least two positions close to either end of the specific direction relative to the central position. Equipped with, The first fixing member covers a length range of 1 / 4 or more of the length of the target side, and fixes the target end, which is the end of the electrode body corresponding to the target side. The second fixing member is wrapped around the electrode body for a length of one or more turns along a winding direction perpendicular to the specific direction at the central position and at least two of the other positions. The tension of the second fixing member wrapped around the central position is greater than the tension of the second fixing member wrapped around each of the at least two positions. A secondary battery characterized by the following features.

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