JP2015109170A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the performance and durability of a battery regardless of expansion of a case 14.SOLUTION: A plurality of collector terminals 20 are projected from both axial ends of an axially extending coil body 12 of oval cross-section with a space between them in a direction of the short axis of the oval. The coil body 12 and collector terminals 20 are accommodated in a case 14 such that the direction of the short axis of the oval coincides with the direction of the width of a rectangular parallelepipedic case 14, the direction of the long axis of the oval coincides with the direction of the height of the case 14, and the axial direction of the coil body 12 coincides with the direction of the length of the case 14. Space ensuring parts 34 are provided at both ends of the case 14 in the direction of the length thereof and at least in an intermediate portion of the case 14 in the direction of the height thereof. The space ensuring parts 34 are formed such that the width dimension of the case 14 is greater than the width dimension of a remaining portion, and that a space is ensured between each collector terminal 20 and a side wall of the case 14 while the case 14 has expanded to a predetermined limit value.

Description

  The present invention relates to a battery.

A battery 50 as shown in FIG. 11A is provided (see Patent Document 1).
The battery 50 includes a wound body 52 that is wound with a sheet-like electrode plate and has an elliptical cross section, and extends in the axial direction, and is spaced from both ends in the axial direction of the wound body 52 in the short axis direction of the ellipse. And a plurality of current collecting terminals 54 projecting from each other and extending in the major axis direction of the ellipse, and a rectangular parallelepiped case 56 accommodating the winding body 52 and the current collecting terminals 54.
In this case, the wound body 52 and the current collecting terminal 54 are accommodated in the case 56 such that the minor axis direction of the ellipse coincides with the width direction of the case 56 and the major axis direction of the ellipse coincides with the height direction of the case 56. In this state, the side walls 56 </ b> A (FIG. 11B) of the case 56 are located on both sides of the plurality of current collecting terminals 54 in the width direction of the case 56.

JP 2003-249423 A

In such a battery 50, gas is generated from the wound body 52 by repeating charge and discharge or when the environmental temperature becomes high. Due to the generation of gas, the wound body 52 expands radially outward, and the case 56 also receives gas pressure.
The case 56 expands and deforms due to the expansion of the wound body 52 and the increase in gas pressure in the case 56.
That is, of the side wall 56A of the case 56, the portion near the both ends in the height direction of the case 56 has a small amount of deformation because the rigidity is secured by the lid 56C and the bottom wall 56D, while the height of the side wall 56A. Since the rigidity of the intermediate portion in the direction is not ensured by the lid 56C and the bottom wall 56D compared to the portions near both ends in the height direction, the amount of deformation outward in the width direction is large.
Further, the end portion of the side wall 56A of the case 56 near the both ends in the length direction has a small amount of deformation because rigidity is ensured by the end surface wall 56B, while the lengthwise intermediate portion of the side wall 56A is in the length direction. Since the rigidity is not ensured by the side wall 56A compared to the portions near both ends, the amount of deformation outward in the width direction is large.

For this reason, the middle portion in the height direction and the middle portion in the length direction of the side wall 56 </ b> A of the case 56 are greatly expanded as compared with other portions.
That is, as shown in FIG. 11 (B), when the case 56 is viewed from above the lid body 56C, when the cross section of the intermediate portion in the height direction of the side wall 56A is viewed, the two side walls 56A are The part of the intermediate part in the length direction is greatly expanded as compared with the parts at both ends in the length direction.
Therefore, the positions of both ends in the length direction at the intermediate portion in the height direction of the side wall 56A are displaced in a direction close to the current collecting terminals 54 located at both ends in the width direction of the case 56 among the plurality of current collecting terminals 54. To do.
If the side wall 56A comes into contact with the current collecting terminal 54 due to such deformation of the side wall 56A, there is a concern that stress is applied to the current collecting terminal 54 and the performance and durability of the battery 50 are lowered.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery that is advantageous in securing the performance and durability of the battery even when the case is expanded.

In order to achieve the above object, the invention according to claim 1 is a battery in which a wound body and a current collecting terminal are accommodated in a case, and the case has a larger distance than a distance from the base of the current collecting terminal. In the axial direction of the wound body, a gap securing portion is formed in which a gap between the current collector terminal and the tip portion of the current collector terminal positioned opposite to the base is large.
According to a second aspect of the present invention, in the wound body, the electrode plate is wound and the cross section exhibits an ellipse and extends in the axial direction, and the current collector terminal protrudes from both axial ends of the wound body. And extending in the major axis direction of the ellipse, the case has a rectangular parallelepiped shape, the wound body has the minor axis direction of the ellipse coincident with the width direction of the case, and the major axis direction of the ellipse Are accommodated in the case so that they coincide with the height direction of the case, and the gap securing portions are formed on the side wall portions of at least an intermediate portion in the height direction of the case at both ends in the length direction of the case. It is characterized by.
According to a third aspect of the present invention, a safety valve is provided at one end portion in the height direction of the case, and the clearance securing portion extends from an intermediate portion in the height direction of the case to one end in the height direction. It is provided over the part.
According to a fourth aspect of the present invention, at the end faces of both ends in the length direction of the case, the portion connecting the both ends in the width direction of the case of the gap securing portion is convex in the direction away from the case in the width direction. It is characterized by being formed with a curved surface.

According to the first aspect of the present invention, even when the case expands and deforms to a predetermined limit value, the gap is secured between the case and the current collecting terminal by the gap securing portion. Therefore, even if the case expands, it can be prevented that the case contacts the current collecting terminal and stress is applied to the current collecting terminal, which is advantageous in securing the performance and durability of the battery.
According to the second aspect of the present invention, the wound body and the current collector terminal have the minor axis direction of the ellipse of the wound body coincided with the width direction of the case and the major axis direction of the ellipse coincides with the height direction of the case. This is advantageous in securing the performance and durability of the battery accommodated in the case.
According to the third aspect of the present invention, when the gas generated from the wound body flows out from both ends in the axial direction of the wound body, the gas can be smoothly released toward the safety valve by the clearance securing portion. This is advantageous in reliably releasing the internal pressure by the safety valve when the internal pressure exceeds the upper limit.
According to the fourth aspect of the present invention, when the case is expanded, the end face walls at both ends are separated from the current collecting terminals without the end faces at both ends being deformed in a direction approaching the current collecting terminals in the length direction of the case. It is easy to deform in the direction, which is advantageous in preventing contact with the current collecting terminal.

It is front sectional drawing which shows the structure of the battery of 1st Embodiment. 1B is a sectional view taken along line BB in FIG. 1A, FIG. 1C is a sectional view taken along line CC in FIG. 1, and FIG. 2D is a sectional view taken along line DD in FIG. (E) is a view taken in the direction of arrow E in FIG. 1, (F) is a cross-sectional view taken along the line FF in FIG. 1, and (G) is a view taken in the direction of arrow G in FIG. (A) is sectional drawing corresponding to FIG.3 (F) which shows the state at the time of case expansion | swelling in the battery of 1st Embodiment, (B) is BB sectional drawing of (A). It is explanatory drawing which expanded a part of winding body. It is A arrow directional view of FIG. It is an end view which shows the structure of the battery of 2nd Embodiment. (B) is a B arrow view of FIG. 7, (C) is CC sectional view taken on the line of FIG. 7, (D) is D arrow view of FIG. It is an end view which shows the structure of the battery of 3rd Embodiment. (B) is a B arrow view of FIG. 9, (C) is CC sectional view taken on the line of FIG. 9, (D) is D arrow view of FIG. (A) is front sectional drawing which shows the structure of the conventional battery, (B) is sectional drawing which shows the state at the time of case expansion of the conventional battery.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In this embodiment, the battery according to the present invention is a lithium ion secondary battery, which is mounted on an electric vehicle such as an electric vehicle or a plug-in hybrid vehicle that uses a motor as a drive source, and supplies electric power to the motor. A case where
The present invention is not limited to lithium ion secondary batteries, and can be used for various conventionally known primary batteries or secondary batteries.

  First, the configuration of the battery 10A will be described. As shown in FIG. 1, the battery 10 </ b> A includes a wound body 12, a case 14, a positive terminal 16 </ b> A and a negative terminal 16 </ b> B, a safety valve 18, and a current collecting terminal 20.

As shown in FIGS. 5 and 6, the wound body 12 is a member in which a sheet-like electrode plate 22 is wound so that the cross section exhibits an ellipse and extends in the axial direction. In the present embodiment, FIG. As shown in (C), two wound bodies 12 are provided. Note that the number of wound bodies 12 may be one or three or more.
The electrode plate 22 includes a sheet-like positive electrode 24, a sheet-like negative electrode 26, and two separators 28 and 30 sandwiched between the positive electrode 24 and the negative electrode 26.
The positive electrode 24 includes a positive electrode current collector 24A (positive electrode current collector foil) made of a metal foil, and a positive electrode active material 24B formed on the positive electrode current collector 24A.
The positive electrode active material 24B releases lithium ions when the battery 10A is charged, and occludes lithium ions when discharged.
The negative electrode 26 includes a negative electrode current collector 26A (negative electrode current collector foil) made of a metal foil, and a negative electrode active material 26B formed on the negative electrode current collector 26A.
The negative electrode active material 26B occludes lithium ions when the battery 10A is charged and releases lithium ions when discharged.
The separators 28 and 30 are impregnated with an electrolytic solution in which lithium ions move.
As shown in FIGS. 1 and 3F, the edge of the positive electrode current collector 24A protrudes from the outer end of the wound body 12 from one end in the axial direction of the wound body 12. The edge of the negative electrode current collector 26 </ b> A protrudes outside the wound body 12 from the other end portion in the axial direction of the body 12.

As shown in FIGS. 1, 2 </ b> B to 2 </ b> D, and FIGS. 3E to 3 </ b> G, the case 14 has a rectangular parallelepiped shape and includes clearance securing portions 34 at both ends in the longitudinal direction.
The case 14 includes a rectangular bottom wall 1402, two side walls 1404 erected from a pair of long sides of the bottom wall 1402, two end surface walls 1406 erected from a pair of short sides of the bottom wall 1402, The side wall 1404 is connected to the upper edge of the end wall 1406, and a lid 1408 constituting the upper wall is provided.
Therefore, the end face walls 1406 are located at both ends of the case 14 in the longitudinal direction, and the side walls 1404 are located at both ends of the case 14 in the width direction.
The wound body 12 and the current collecting terminal 20 have the minor axis direction of the ellipse coincident with the width direction of the case 14, the major axis direction of the ellipse coincides with the height direction of the case 14, and the axial direction of the wound body 12 is The case 14 is accommodated in the case 14 so as to coincide with the length direction of the case 14.
Side walls 1404 of the case 14 are located on both sides of the plurality of current collecting terminals 20 in the width direction of the case 14.

The clearance securing portions 34 are provided at both ends of the case 14 in the length direction at least on the side wall 1404 portion in the height direction of the case 14. The gap securing part 34 has a larger distance from the front part of the current collecting terminal 20 positioned opposite to the base part in the axial direction of the wound body 12 than the distance from the base part of the current collecting terminal 20 located on the case 14 side. As shown, the current collector terminal 20 and the side wall 1404 of the case 14 have a dimension in the width direction of the case 14 larger than the dimension in the width direction of the remaining portion, and the case 14 has expanded to a predetermined limit value. It is formed so as to ensure a gap between them.
Here, the limit value of the case 14 corresponds to the expansion amount of the case 14 corresponding to the case where the internal pressure of the case 14 becomes a value sufficient to open the safety valve 18.

In the present embodiment, the clearance securing portion 34 is provided over the entire area of the case 14 in the height direction.
More specifically, as shown in FIG. 3 (G), the bottom surface 1402 gradually increases in width toward the both ends in the length direction of the bottom wall 1402 as the distance from the central portion in the length direction of the bottom wall 1402 increases. A wall portion 1402A is formed. Further, as shown in FIG. 3E, a lid portion 1408A is formed at both ends in the length direction of the lid body 1408 so that the width of the lid body 1408 gradually increases as the distance from the center in the length direction of the lid body 1408 increases. Has been. As shown in FIG. 3 (F), both ends of the side wall 1404 connect the bottom wall portion 1402A and the lid body portion 1408A, and the distance between the side walls 1404 increases as the distance from the central portion in the length direction of the side wall 1404 increases. A side wall portion 1404A is formed to gradually increase the width. The end wall 1406 connects the end of the bottom wall portion 1402A, the end of the lid portion 1408A, and the end of the side wall portion 1404A.
Therefore, the clearance securing part 34 is configured by an end portion of the bottom wall portion 1402A, an end portion of the lid portion 1408A, and an end portion of the side wall portion 1404A.

  Further, as shown in FIG. 3F, a portion of the gap securing portion 34 connecting both ends in the width direction of the case 14, that is, the end face wall 1406 is convex in a direction in which the center in the width direction is separated from the case 14. It is formed by a curved surface 1406A. When the end face walls 1406 at both ends are formed by the curved faces 1406A in this way, when the case 14 expands, the end face walls 1406 at both ends do not deform in a direction approaching the current collecting terminal 20 in the length direction of the case 14. The end face walls 1406 at both ends are easily deformed in the direction away from the current collecting terminal 20, which is advantageous in preventing contact with the current collecting terminal 20.

The positive terminal 16A and the negative terminal 16B are used for taking out electric power from the battery 10A to an external device and charging the electric power from the charging device to the battery 10A.
The positive electrode terminal 16 </ b> A and the negative electrode terminal 16 </ b> B are provided at positions near both sides in the length direction of the lid body 1408, and are electrically connected to the current collecting terminals 20, respectively.

The safety valve 18 releases the internal pressure when the internal pressure in the case 14 is increased by the gas generated from the wound body 12 and the internal pressure exceeds the upper limit.
In the present embodiment, the safety valve 18 is provided at an intermediate portion in the length direction of the lid body 1408 that forms one end portion of the case 14 in the height direction.

The current collection terminal 20 is for taking out electric power from the wound body 12, or for charging electric power to the wound body 12, and is comprised with the metal material which can change easily, such as aluminum.
The current collector terminal 20 includes a positive electrode current collector terminal 20A that electrically connects the positive electrode current collector 24A and the positive electrode terminal 16A, and a negative electrode current collector terminal 20B that electrically connects the negative electrode current collector 26A and the negative electrode terminal 16B. And.
In this embodiment, each winding body 12 is provided with one positive current collecting terminal 20A and one negative current collecting terminal 20B. Therefore, in this embodiment, four current collecting terminals 20 are provided.

As shown in FIGS. 1, 2 </ b> B, and 2 </ b> C, each current collecting terminal 20 protrudes from both ends in the axial direction of the wound body 12, and each current collecting terminal 20 has a width of the case 14. It is located at both ends in the direction (both ends in the minor axis direction of the ellipse).
The plurality of current collecting terminals 20 have a length that extends in the major axis direction of the ellipse and a width that projects in the axial direction of the wound body 12.

More specifically, as shown in FIG. 3F, the positive electrode current collector terminal 20A extends from the lower end in the major axis direction to the upper portion of the positive electrode current collector 24A protruding from one end in the axial direction of the wound body 12. It is electrically connected to the positive electrode current collector 24A by being welded to the crossed place.
The upper ends of the positive electrode current collecting terminals 20A are electrically connected to the positive electrode terminals 16A by welding via positive electrode connecting plate portions 32A having an L shape.
Further, as shown in FIGS. 2C and 3F, the negative electrode current collector terminal 20B is the long axis of the portion of the negative electrode current collector 26A that protrudes from the other end of the wound body 12 in the axial direction. It is electrically connected to the negative electrode current collector 26 </ b> A by being welded at a position extending from the lower part to the upper part in the direction.
The negative electrode current collector terminal 20B is electrically connected at its upper end to the negative electrode terminal 16B by welding via an L-shaped negative electrode connection plate portion 32B.

Next, the function and effect of the battery 10A of the present embodiment will be described.
The case 14 is not limited to an installation mode in which the lid body 1408 is placed up, but is installed in a state in which one side wall 1404 is up or one end wall 1406 is up. The manner in which the case 14 is installed, such as the installation manner installed in a state, is appropriately determined according to the shape of the space in which the battery 10A is accommodated.
As shown in FIGS. 4 (A) and 4 (B), the wound body 12 is radiated in the radial direction by generating gas from the wound body 12 by repeating charging / discharging or by increasing the environmental temperature. The case 14 expands outward, and the case 14 is also subjected to gas pressure.
Here, the gas generated from the wound body 12 flows out from both ends of the wound body 12 in the axial direction. This is because, as shown in FIGS. 5 and 6, the wound body 12 has a structure in which the electrode plate 22 with the separators 28 and 30 interposed between the positive electrode 24 and the negative electrode 26 is wound a plurality of times. .
The case 14 expands and deforms due to the expansion of the wound body 12 and the increase in gas pressure in the case 14.
That is, the portion of the side wall 1404 of the case 14 near the both ends in the height direction of the case 14 has a small amount of deformation because the lid 1408 and the bottom wall 1402 ensure rigidity, while the height of the side wall 1404 is low. Since the rigidity of the intermediate portion in the direction is not ensured by the lid body 1408 and the bottom wall 1402 compared to the portions near both ends in the height direction, the amount of deformation outward in the width direction is large.
Further, since the rigidity is ensured by the end face wall 1406, the portion near the both ends in the length direction of the side wall 1404 of the case 14 is less deformed, while the intermediate part in the length direction of the side wall 1404 is in the length direction. Since the rigidity is not ensured by the side wall 1404 compared to the portions near both ends, the amount of deformation outward in the width direction is large.

For this reason, the portion of the intermediate portion in the height direction and the intermediate portion in the length direction of the side wall 1404 of the case 14 is greatly expanded as compared with the remaining portions.
That is, as shown in FIG. 4A, when the case 14 is viewed from above the lid body 1408, when the cross section of the middle portion in the height direction of the side wall 1404 is viewed, the two side walls 1404 are The part of the intermediate part in the length direction is greatly expanded as compared with the parts at both ends in the length direction.
Therefore, the positions of both ends in the length direction at the intermediate portion in the height direction of the side wall 1404 are displaced in a direction close to the current collecting terminals 20 located at both ends in the width direction of the case 14 among the plurality of current collecting terminals 20. To do.
However, in the present embodiment, a gap is secured between the current collecting terminal 20 and the side wall 1404 of the case 14 in a state where the case 14 has expanded to a predetermined limit value at both ends in the length direction of the case 14. A gap securing portion 34 is formed.
Therefore, even when the case 14 expands and deforms to a predetermined limit value, a gap is secured between the side wall 1404 and the current collecting terminal 20.
Therefore, even if the case 14 expands, the side wall 1404 can be prevented from coming into contact with the current collecting terminal 20 and stress being applied to the current collecting terminal 20, which is advantageous in ensuring the performance and durability of the battery 10A. Become.
Further, in the present embodiment, since the gap securing portion 34 extends over the entire length in the height direction of the case 14, a gap is secured for the gas flow path from both ends in the axial direction of the wound body 12 to the safety valve 18. It can be secured by the part 34.
Therefore, when the gas generated from the wound body 12 flows out from both ends in the axial direction of the wound body 12, the gas can be smoothly released toward the safety valve 18 by the clearance securing portion 34, and the internal pressure in the case 14 is reduced. When the upper limit is exceeded, the safety valve 18 is advantageous for reliably opening the internal pressure.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. 7 and 8B to 8D. In the following embodiments, the same or similar parts and members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
The second embodiment is different from the first embodiment in that the gap securing portion 34 of the battery 10B is provided from an intermediate portion in the height direction of the case 14 to one end portion in the height direction. Yes.
In the second embodiment as well, as in the first embodiment, the contact between the side wall 1404 and the current collecting terminal 20 can be prevented even when the case 14 expands, and the performance and durability of the battery 10 can be prevented. It is advantageous in securing the property. Further, a gas flow path extending from both ends in the axial direction of the wound body 12 to the safety valve 18 can be secured by the clearance securing portion 34, and when the internal pressure in the case 14 exceeds the upper limit, the internal pressure is reliably ensured by the safety valve 18. This is advantageous for opening the door.
In the second embodiment, since the volume of the gap securing portion 34 is smaller than that in the first embodiment, the weight of the case 14 can be reduced. Therefore, for example, when the battery is mounted on the electric vehicle in units of tens or hundreds, it is advantageous in reducing the weight of the battery and reducing the weight of the electric vehicle.

(Third embodiment)
Next, a third embodiment will be described with reference to FIGS. 9 and 10B to 10D.
The third embodiment is different from the first and second embodiments in that the gap securing portion 34 of the battery 10C is provided only in the intermediate portion in the height direction of the case 14.
In such a third embodiment, since the gap passage 34 cannot secure a gas flow path from both ends in the axial direction of the wound body 12 to the safety valve 18, the safety valve 18 can reliably release the internal pressure. Although it is disadvantageous compared to the first and second embodiments, as in the first embodiment, contact between the side wall 1404 and the current collecting terminal 20 can be prevented even if the case 14 expands, This is advantageous in securing the performance and durability of the battery 10.
In the second embodiment, since the volume of the gap securing portion 34 is smaller than that in the first and second embodiments, the weight of the case 14 can be further reduced. Therefore, for example, when the battery is mounted on the electric vehicle in units of several tens or hundreds, it is further advantageous to reduce the weight of the battery and reduce the weight of the electric vehicle.

  In addition, the shape of the wound body 12 or the arrangement structure of the wound body 12 in the case 14 and the arrangement structure of the current collecting terminals 20 with respect to the wound body 12 are not limited to the embodiment, and can be variously considered. Correspondingly, the configuration of the gap securing part 34 is appropriately determined, and therefore the configuration of the gap securing part 34 is not limited to the structure of the embodiment.

10A, 10B, 10C Battery 12 Winding body 14 Case 1404 Side wall 1404A Side wall portion 1406A Curved surface 18 Safety valve 20 Current collecting terminal 22 Electrode plate 34 Clearance securing portion

Claims (4)

A battery in which a wound body and a current collecting terminal are housed in a case,
In the case, there is a gap securing portion in which a gap between the current collector terminal and the front portion of the current collector terminal that is positioned opposite to the base in the axial direction of the wound body is larger than a distance from the base portion of the current collector terminal. Formed,
A battery characterized by that. The wound body, the electrode plate is wound, the cross section exhibits an ellipse and extends in the axial direction,
The current collector terminals project from both axial ends of the wound body and extend in the major axis direction of the ellipse,
The case has a rectangular parallelepiped shape,
The wound body is accommodated in the case with the short axis direction of the ellipse coinciding with the width direction of the case and the long axis direction of the ellipse coinciding with the height direction of the case;
The clearance securing portion is formed on the side wall portion of at least an intermediate portion in the height direction of the case at both ends in the length direction of the case.
The battery according to claim 1. A safety valve is provided at one end of the case in the height direction;
The gap ensuring part is provided from one intermediate part in the height direction to one end part in the height direction of the case,
The battery according to claim 2. The portion of the gap securing portion that connects both ends in the width direction of the case at the end surfaces at both ends in the length direction of the case is formed with a curved surface that is convex in the direction in which the center in the width direction is away from the case. Yes,
The battery according to claim 2.

Images