Secondary battery
By securing electrode bodies with case wall grooves and integrating terminals, the secondary battery addresses movement and damage risks during vibrations, enhancing stability and capacity flexibility.
Patent Information
- Application Number
- JP2023122513
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-07-27
- Publication Date
- 2025-02-06
AI Technical Summary
Secondary batteries experience movement of electrode bodies within the case due to vibrations, risking damage to the joints between the electrode bodies and current collector terminals.
The electrode bodies are secured using grooves on the inner surfaces of the case walls, and the current collector terminals are integrated with external terminals, with recesses on the inner surface to accommodate smoke and a simplified structure to reduce component count.
The solution effectively prevents electrode body movement during vibrations, reduces damage risk, allows smoke discharge, minimizes component count, and simplifies the energization path, while enabling easy capacity adjustment by changing the number of electrode bodies.
Smart Images
Figure 2025018631000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a secondary battery, such as a lithium ion battery. [Background technology]
[0002] Conventionally, as an example of this type of secondary battery, one shown in Patent Document 1 has been known. This type of secondary battery has a configuration in which a plurality of electrode assemblies, each of which is formed by winding positive and negative electrode sheets stacked with a separator sandwiched therebetween, are housed in a case. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] International Publication No. 2017 / 204137 Summary of the Invention [Problem to be solved by the invention]
[0004] Incidentally, when the above-mentioned secondary battery is mounted on, for example, an automobile, it is subjected to vibrations while the automobile is moving. This causes the multiple electrode bodies to move within the case, and there is a risk that the joints between the electrode bodies and the current collectors (current collector terminals) may be damaged. [Means for solving the problem]
[0005] Various aspects of the secondary battery for solving the above problems will be described below. A secondary battery comprising: a plurality of electrode bodies formed by winding positive and negative electrode sheets stacked with a separator therebetween; and a case housing the plurality of electrode bodies, each of the electrode sheets having a sheet-like current collector and an electrode active material layer stacked on the current collector, the plurality of electrode bodies being housed in the case with the winding axis of the electrode body extending in a direction along a bottom surface of the case and lined up in a direction perpendicular to the bottom surface, a pair of first side walls of the case facing each other in the winding axis direction of the electrode body have plate-like current collecting terminals arranged on their inner surfaces that contact the current collectors of the electrode bodies, and external terminals electrically connected to the current collecting terminals arranged on their outer surfaces, and a pair of second side walls of the case facing each other in the direction perpendicular to the winding axis direction are each formed with a plurality of grooves that fit into the plurality of electrode bodies and hold the plurality of electrode bodies in place.
[0006] According to the above configuration, the electrode bodies are sandwiched in a plurality of grooves formed on the inner surfaces of the pair of second side walls, and therefore the electrode bodies can be prevented from moving within the case even when the case is subjected to vibration.
[0007] [Aspect 2] The secondary battery according to [Aspect 1], characterized in that the inner surface of the collector terminal is formed with recesses facing the plurality of electrode bodies. According to the above configuration, smoke generated when the multiple electrode bodies overheat can be contained by the recess.
[0008] [Aspect 3] The secondary battery according to [Aspect 1] or [Aspect 2], wherein the current collecting terminal and the external terminal are integrally formed. According to the above configuration, the number of parts can be reduced compared to a case in which the current collecting terminal and the external terminal are formed separately. Effect of the Invention
[0009] The present invention has the advantage that it is possible to prevent a plurality of electrode bodies from moving within the case even when subjected to vibration. [Brief description of the drawings]
[0010] [Figure 1] 1 is a perspective view of a secondary battery according to an embodiment; [Diagram 2] FIG. 2 is an exploded perspective view of a secondary battery. [Diagram 3] FIG. [Figure 4] FIG. 2 is a cross-sectional view of a secondary battery. [Diagram 5] FIG. 3 is an exploded perspective view showing a state in which the electrode body is omitted in FIG. 2. [Figure 6] FIG. 6 is an exploded perspective view of FIG. 5 as seen from the opposite side. [Figure 7] FIG. [Figure 8] 4 is a cross-sectional view showing the positional relationship between a plurality of electrode bodies and recesses in a secondary battery. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] An embodiment will now be described with reference to the drawings. <Secondary battery 11> As shown in Fig. 1, the secondary battery 11 has a generally rectangular plate shape. In the following description, the long side direction is X, the thickness direction is Y, and the short side direction is Z in the orientation of the secondary battery 11 in Fig. 1. In the secondary battery 11 of this embodiment, the long side direction X and the thickness direction Y coincide with the horizontal direction, and the short side direction Z coincides with the vertical direction. The long side direction X, the thickness direction Y, and the short side direction Z are perpendicular to each other. In the following description, "upper" and "lower" refer to "upper" and "lower" in the orientation of the secondary battery 11 in Fig. 1.
[0012] 1 and 2, a secondary battery 11 includes a plurality of electrode bodies 12 and a case 13 that houses the plurality of electrode bodies 12. The secondary battery 11 of this embodiment has a configuration as a lithium ion secondary battery in which each electrode body 12 in the case 13 is impregnated with a non-aqueous electrolyte solution (not shown). The electrolyte solution used is one in which a lithium salt serving as a supporting salt is dissolved in an organic solvent.
[0013] <Electrode body 12> As shown in Fig. 3, the electrode body 12 is configured by laminating and integrating a strip-shaped positive electrode sheet 14 as an example of an electrode sheet, a strip-shaped negative electrode sheet 15 as an example of an electrode sheet, and a strip-shaped separator 16. That is, the laminate of the positive electrode sheet 14, the negative electrode sheet 15, and the separator 16 is wound around a winding axis L extending in the width direction. In this way, the electrode body 12 is formed in which the positive electrode sheet 14 and the negative electrode sheet 15 are alternately arranged in the radial direction with the separator 16 sandwiched between them. The separator 16 is formed, for example, of a porous film made of an insulating synthetic resin.
[0014] The positive electrode sheet 14 has a strip-shaped positive electrode current collector 17 as an example of a sheet-shaped current collector, and a positive electrode active material layer 18 as an example of an electrode active material layer laminated on the positive electrode current collector 17. The positive electrode current collector 17 is made of, for example, aluminum foil. The positive electrode active material layer 18 is laminated on the positive electrode current collector 17 by applying a composite paste containing a lithium transition metal oxide serving as a positive electrode active material and a binder onto the positive electrode current collector 17.
[0015] In this case, the positive electrode active material layer 18 is laminated on the positive electrode current collector 17 in a state where one edge portion in the width direction of the positive electrode current collector 17 is exposed. The exposed portion of the positive electrode current collector 17 that is not covered by the positive electrode active material layer 18 is defined as a positive electrode exposed portion 19.
[0016] The negative electrode sheet 15 has a strip-shaped negative electrode current collector 20 as an example of a sheet-shaped current collector, and a negative electrode active material layer 21 as an example of an electrode active material layer laminated on the negative electrode current collector 20. The negative electrode current collector 20 is made of, for example, copper foil. The negative electrode active material layer 21 is laminated on the negative electrode current collector 20 by applying a composite paste containing a carbon-based material serving as a negative electrode active material and a binder onto the negative electrode current collector 20.
[0017] In this case, the negative electrode active material layer 21 is laminated on the negative electrode current collector 20 in a state where the other edge portion opposite to the positive electrode exposed portion 19 in the width direction of the negative electrode current collector 20 is exposed. The exposed portion of the negative electrode current collector 20 that is not covered by the negative electrode active material layer 21 is defined as a negative electrode exposed portion 22.
[0018] 3 and 4, the cross section of the electrode body 12 cut in a plane perpendicular to the winding axis L has a shape obtained by squashing a perfect circle and flattening it. That is, in the electrode body 12, one pair of mutually opposing surfaces is a flat surface 23, and the other pair of mutually opposing surfaces is an arc surface 24. That is, in the electrode body 12, in FIG. 4, both sides in the short side direction Z that coincides with the up-down direction are flat surfaces 23, and both sides in the thickness direction Y that coincides with the left-right direction are arc surfaces 24 that bulge in an arc shape.
[0019] <Case 13> 2 to 4, the case 13 is made of, for example, synthetic resin. The case 13 includes a case body 25 in the shape of a flat rectangular box with a bottom, and a rectangular plate-like cover member 27 that closes a rectangular opening 26 that opens to one side of the case body 25 in the thickness direction Y. A plurality of electrode bodies 12 (ten in this example) are housed in the case 13 with the winding axes L of the electrode bodies 12 extending in a long side direction X that is a direction along the bottom surface 28 of the case 13, and aligned in a short side direction Z that is a direction perpendicular to the bottom surface 28.
[0020] In this case, the multiple electrode bodies 12 are arranged side by side such that the flat surfaces 23 of two electrode bodies 12 adjacent to each other in the short side direction Z are in contact with each other. That is, each electrode body 12 is arranged in a position in which a pair of flat surfaces 23 face each other in the short side direction Z and a pair of arcuate surfaces 24 face each other in the thickness direction Y.
[0021] 2, 3, and 5, a pair of side walls facing each other in the long side direction X, which is the winding axis direction in which the winding axis L of the electrode body 12 housed in the case body 25 extends, are defined as first side walls 29. A first long hole 30 is formed penetrating through the center of each of the pair of first side walls 29 in the short side direction Z. The first long hole 30 is closed by a plate-like sealing member 31 that is weaker than the first side walls 29. The sealing member 31 has the same shape as the first long hole 30, and is fixed in a state where it is fitted into the first long hole 30.
[0022] 5 and 7, a metal terminal-forming member 32 is provided on each of the pair of first side walls 29 by, for example, insert molding. The terminal-forming member 32 is configured such that a current collecting terminal 33 and an external terminal 34 are integrally formed via a connecting portion 35.
[0023] The current collecting terminal 33 has a rectangular plate shape extending in the short side direction Z, and is disposed so as to cover the entire inner surface of the first side wall 29. That is, the current collecting terminal 33 is disposed on the inner surface of the first side wall 29. A second long hole 36, which is one size larger than the first long hole 30, is formed penetrating the current collecting terminal 33 at a position facing the first long hole 30 in the long side direction X. The first long hole 30 and the second long hole 36 are in communication with each other.
[0024] 5 and 8, a recess 37 is formed on the inner surface of the current collecting terminal 33, facing the multiple electrode bodies 12 housed in the case body 25 in the short side direction Z. The recess 37 extends over almost the entire short side direction Z of the inner surface of the current collecting terminal 33. The second long hole 36 is located in the center of the recess 37 in the short side direction Z.
[0025] 5 and 7, a block-shaped external terminal 34 larger than the connecting portion 35 is integrally formed on the outer surface of the current collecting terminal 33 at a position closer to the bottom surface 28 (lower) than the second elongated hole 36 via the block-shaped connecting portion 35. The external terminal 34 is electrically connected to the current collecting terminal 33 via the connecting portion 35. The connecting portion 35 is embedded in the first side wall 29. The external terminal 34 is exposed from the outer surface of the first side wall 29. That is, the external terminal 34 is disposed on the outer surface of the first side wall 29.
[0026] As shown in Figures 2, 5 and 7, each of the collector terminals 33 covering the inner surfaces of a pair of first side walls 29 is adhered by a conductive adhesive while being in contact with the positive electrode exposed portion 19 of the positive electrode collector 17 of the multiple electrode bodies 12 housed in the case body 25 on one side, and is adhered by a conductive adhesive while being in contact with the negative electrode exposed portion 22 of the negative electrode collector 20 of the multiple electrode bodies 12 housed in the case body 25 on the other side.
[0027] In this case, of the external terminals 34 arranged on the outer surfaces of a pair of first side walls 29, the one corresponding to the collector terminal 33 electrically connected to the positive electrode collector 17 of the electrode body 12 serves as the positive electrode terminal of the secondary battery 11, and the one corresponding to the collector terminal 33 electrically connected to the negative electrode collector 20 of the electrode body 12 serves as the negative electrode terminal of the secondary battery 11.
[0028] 4 to 6, a pair of side walls opposing each other in a thickness direction Y perpendicular to a long side direction X which is the winding axis direction of the electrode body 12 housed in the case body 25 are second side walls 38. In this case, one of the pair of second side walls 38 is formed by a wall on the opposite side to the opening 26 side of the case body 25, and the other is formed by the cover member 27.
[0029] A plurality of grooves 39 are formed on the inner surfaces of the pair of second side walls 38, which engage with the arc surfaces 24 of the plurality of electrode bodies 12 housed in the case 13 and hold the plurality of electrode bodies 12 in the thickness direction Y. The plurality of grooves 39 of each of the pair of second side walls 38 extend in the long side direction X and are arranged side by side so as to be parallel to each other in the short side direction Z.
[0030] The grooves 39 are arc-shaped corresponding to the arc surfaces 24 of the electrode bodies 12. Then, with the opening 26 in the case body 25 containing the electrode bodies 12 sealed by the lid member 27, the case body 25 and the lid member 27 are joined by welding or the like. Then, the grooves 39 on the inner surface of each of the pair of second side walls 38 are pressed against the arc surfaces 24 of the electrode bodies 12 in the case 13 on both sides in the thickness direction Y while being fitted thereto in the thickness direction Y. This causes the electrode bodies 12 to be firmly fixed in the case 13.
[0031] <Operation of the embodiment> Generally, when a secondary battery with an electrode body housed in a case is mounted on, for example, an automobile, the secondary battery is subjected to vibrations while the automobile is running. When the secondary battery is subjected to such vibrations, the electrode body moves within the case, and there is a risk that the joint between the electrode body and the current collecting terminal may be damaged.
[0032] In this regard, in the secondary battery 11 of the present embodiment, the multiple electrode bodies 12 are sandwiched in a state in which they are fitted into the multiple grooves 39 on the inner surfaces of the pair of second side walls 38 within the case 13. Therefore, in the secondary battery 11, the multiple electrode bodies 12 within the case 13 are firmly fixed.
[0033] Therefore, even if the secondary battery 11 is subjected to vibration, the multiple electrode bodies 12 are prevented from moving within the case 13, thereby reducing the risk of damage due to vibration to the joints between the electrode bodies 12 and the collector terminals 33 within the case 13, etc.
[0034] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) In the secondary battery 11, a pair of opposing second side walls 38 of the case 13 are formed on their inner surfaces with a plurality of grooves 39 that fit with the plurality of electrode bodies 12 and hold the plurality of electrode bodies 12 therebetween.
[0035] According to the above configuration, the electrode bodies 12 are sandwiched in a state where the electrode bodies 12 are fitted into the grooves 39 formed on the inner surfaces of the pair of second side walls 38. Therefore, even if the secondary battery 11 is subjected to vibration, the electrode bodies 12 can be prevented from moving within the case 13. This reduces the risk that the joints between the electrode bodies 12 and the current collecting terminals 33 within the case 13 will be damaged by vibration.
[0036] (2) In the secondary battery 11 , the inner surface of the current collecting terminal 33 is formed with recesses 37 that face the plurality of electrode bodies 12 . According to the above configuration, smoke generated when the electrode bodies 12 overheat can be contained by the recess 37 in the case 13. Furthermore, when the pressure inside the case 13 reaches or exceeds a predetermined value due to overheating of the electrode bodies 12, the sealing member 31 is destroyed by the pressure. As a result, the smoke contained in the recess 37 can be exhausted to the outside of the case 13 through the second elongated hole 36 and the first elongated hole 30.
[0037] (3) In the secondary battery 11, the current collecting terminal 33 and the external terminal 34 are integrally formed. According to the above configuration, the number of parts can be reduced compared to a case where the current collecting terminal 33 and the external terminal 34 are formed separately.
[0038] (4) In the secondary battery 11 , the external terminals 34 are disposed on the outer surfaces of the pair of first side walls 29 . According to the above configuration, the current path from the electrode body 12 to the external terminal 34 can be made shorter than when the external terminal 34 is disposed on the upper part of the case 13 .
[0039] (5) In the secondary battery 11, the multiple electrode bodies 12 are arranged side by side in the short side direction Z within the case 13 with the flat surfaces 23 facing the short side direction Z. Normally, each electrode body 12 expands due to a temperature rise, but the direction of expansion coincides with the short side direction Z in which the flat surface 23 is located. Therefore, according to the above configuration, the load when each electrode body 12 expands can be received by both walls of the case 13 in the short side direction Z, so that the expansion of each electrode body 12 can be suppressed. In this case, a tensile load in the short side direction Z due to the expansion of each electrode body 12 acts on the pair of second side walls 38, but no moment of force acts on them. Therefore, the expansion of each electrode body 12 can be suppressed even if multiple secondary batteries 11 are not stacked in the thickness direction Y. Therefore, the secondary battery 11 can be used alone.
[0040] (6) In the secondary battery 11 , a plurality of electrode assemblies 12 are housed within the case 13 . According to the above configuration, the capacity of the secondary battery 11 can be easily changed simply by changing the number of electrode bodies 12 housed in the case 13. In this case, it is preferable to change the size of the case 13 to match the number of electrode bodies 12 housed therein, but there is no need to change the manufacturing process of the electrode body 12. In other words, there is no need to change the number of windings of the electrode body 12.
[0041] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other as long as they are not technically inconsistent.
[0042] The current collecting terminal 33 and the external terminal 34 do not necessarily have to be integrally formed. That is, the current collecting terminal 33 and the external terminal 34 may be formed separately. The recess 37 on the inner surface of the current collecting terminal 33 may be omitted.
[0043] The number of electrode assemblies 12 housed in case 13 may be changed as appropriate so long as it is more than one. In this case, it is preferable to change the size of case 13 to match the number of electrode assemblies 12 housed therein.
[0044] The secondary battery 11 may be a secondary battery having a configuration other than that of a lithium ion secondary battery. [Explanation of symbols]
[0045] 11…Secondary battery 12...Electrode body 13…Case 14...Positive electrode sheet as an example of an electrode sheet 15...Negative electrode sheet as an example of an electrode sheet 16…Separator 17...Positive electrode current collector as an example of a current collector 18...Positive electrode active material layer as an example of an electrode active material layer 19…Positive electrode exposed part 20... Negative electrode current collector as an example of a current collector 21... Negative electrode active material layer as an example of an electrode active material layer 22...Negative electrode exposed part 23…Flat surface 24...Arc surface 25…Case body 26…Opening 27…Cover member 28…Bottom 29…First side wall 30…1st long hole 31...Sealing member 32...Terminal forming member 33...Current collector terminal 34…External terminal 35...Connection part 36…Second long hole 37…Recess 38…Second side wall 39...Groove L…winding shaft X: Long side direction Y: Thickness direction Z: Short side direction
Claims
1. A plurality of electrode assemblies formed by winding positive and negative electrode sheets stacked with separators interposed therebetween; A case that accommodates a plurality of the electrode assemblies, Each of the electrode sheets has a sheet-shaped current collector and an electrode active material layer laminated on the current collector, The electrode bodies are housed in the case with winding axes of the electrode bodies extending in a direction along a bottom surface of the case and aligned in a direction perpendicular to the bottom surface, a pair of first side walls of the case facing each other in the winding axis direction of the electrode body have plate-shaped current collecting terminals arranged on their inner surfaces in contact with the current collectors of the electrode body, and external terminals electrically connected to the current collecting terminals arranged on their outer surfaces, A secondary battery characterized in that a pair of second side walls of the case that face each other in a direction perpendicular to the winding axis direction have a plurality of grooves formed on their inner surfaces that engage with a plurality of the electrode bodies and sandwich the plurality of the electrode bodies.
2. 2. The secondary battery according to claim 1, wherein the inner surface of the current collecting terminal is formed with recesses facing the plurality of electrode bodies.
3. 3. The secondary battery according to claim 1, wherein the current collecting terminal and the external terminal are integrally formed.
Citation Information
Patent Citations
Electricity storage element, electricity storage device provided with electricity storage element, moving body provided with electricity storage element, and electricity storage system provided with electricity storage element
WO2017204137A1