JP2017212120A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery that is able to hinder metal deposition by partial pressure of an electrode forming an electrode wound body in a battery cell while ensuring restricting load on a plurality of battery cells.SOLUTION: A battery 10 comprises: a plurality of battery cells 1, each of which is formed by housing in a battery case of flat box shape an electrode wound body 3 in which a positive electrode and a negative electrode are wound flat with a separator between them; a spacer 20A interposed in one space between battery cells 1 arranged in one direction; and restricting means 12a, 12b, 14 that apply restricting load F1 on the plurality of battery cells 1 and the spacer 20A. The battery case 2 has a flexible side wall 2b. The spacer 20A includes a low spring constant projection 24a and high spring constant projection 24b abutting on a side wall 2b. In the spacer 20A, the low spring constant projection 24a abuts on the side wall 2b in the position where the low spring constant projection faces the electrode wound body 3, and the high spring constant projection 24b abuts on the side wall 2b in the position where the high spring constant projection does not face the electrode wound body 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery.

  Conventionally, for example, in Patent Document 1, a pair of plane portions extending in parallel and a pair of curved portions formed continuously between each one end portion and between each other end portion of the pair of plane portions, There is described an assembled battery in which a plurality of rectangular batteries each having a flat wound electrode group having the shape of a rectangular battery are accommodated in a flat box-shaped battery can and a cooling medium is caused to flow between the rectangular batteries.

  In this assembled battery, a boundary spacer is disposed between the adjacent rectangular batteries at a position facing a boundary portion between the flat portion and the curved portion of the flat wound electrode group, and the adjacent rectangular cells. An intermediate spacer is disposed between the batteries at a position facing the flat portion of the flat wound electrode group. By arranging the boundary spacer and the intermediate spacer in this way, it is possible to suppress the battery can from expanding due to heat generated during charging / discharging of the rectangular battery, and as a result, a cooling medium formed between the rectangular batteries. It is described that the reduction of the area of the passage is suppressed and the cooling of each rectangular battery can be sufficiently performed.

International Publication No. 2013/084290

  In the assembled battery described in Patent Document 1, it is necessary to be restrained with a predetermined restraining load acting in the arrangement direction of the square batteries. Thereby, a battery can can be pressed with a boundary part spacer, and expansion of the battery can at the time of heat_generation | fever can be suppressed. However, since the side wall of the battery can made of, for example, an aluminum alloy has flexibility, the flat wound electrode group expanded by heat generation inside the battery is locally pressed by the boundary spacer through the side wall of the battery can. It will be. In this case, a region where the surface pressure is locally increased occurs on the surface of the electrodes constituting the flat wound electrode group, and an electrochemical reaction occurs intensively in a region where the surface pressure difference increases, thereby causing metal precipitation (for example, lithium In the case of an ion battery, lithium deposition) is likely to occur. Such metal deposition causes an internal short circuit between the positive electrode and the negative electrode due to the penetration of the separator.

  On the other hand, for example, resin spacers interposed between the square batteries are continuously pressed and affected by the heat generated by the square batteries, so that creep occurs, which increases the amount of shrinkage (crushing amount) of the spacers. The constraining load in the arrangement direction of the rectangular batteries may be reduced. Therefore, the restraining load for maintaining the state in which each prismatic battery is firmly restrained in the assembled battery as described above is not less than a predetermined lower limit value when assembling the assembled battery in consideration of the creep as described above. It is necessary to set it as large as possible.

  The objective of this invention is providing the battery which can suppress metal deposition by the local press of the electrode which comprises the electrode winding body in a battery cell, ensuring the restraint load with respect to the several battery cell which comprises a battery. .

  A battery according to the present invention includes a plurality of battery cells each configured by accommodating an electrode winding body in which a positive electrode and a negative electrode are wound in a flat shape with a separator interposed therebetween in a flat box-shaped battery case, A battery comprising a spacer interposed between the battery cells arranged along one direction, and a restraining means for applying a restraining load along the one direction to the plurality of battery cells and the spacer. The battery case has a flexible side wall, the spacer includes a low spring constant convex portion and a high spring constant convex portion that contact the side wall, and the low spring constant convex portion of the spacer is The battery case contacts the side wall at a position facing the electrode winding body, and the high spring constant convex portion of the spacer contacts the side wall at a position not facing the electrode winding body within the battery case. thing A.

  According to the battery of the present invention, since the electrode winding body is pressed through the side wall of the battery case by the low spring constant convex portion of the spacer, it is pressed with a relatively weak pressing force. Therefore, the electrode surface pressure difference caused by local pressing of the electrode winding body can be reduced, and metal deposition can be suppressed. Further, the high spring constant convex portion of the spacer can press the side wall of the battery case relatively strongly at a position not facing the electrode winding body, and as a result, the restraining load on each battery cell is equal to or higher than a predetermined lower limit value. Can be secured.

It is a perspective view of the battery which is one Embodiment. (A) is a figure which shows roughly the state which looked at the cell and spacer of this embodiment from the upper part, (b) is the figure which shows schematically the state which looked at the cell and spacer of a comparative example from the upper part It is. (A)-(c) is a figure for demonstrating a mode that the spacer of this embodiment presses a battery case. (A), (b) is a figure which shows other embodiment, respectively.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. In this description, specific shapes, materials, numerical values, directions, and the like are examples for facilitating the understanding of the present invention, and can be appropriately changed according to the application, purpose, specification, and the like. In addition, when a plurality of embodiments and modified examples are included below, it is assumed from the beginning that these configurations are used in appropriate combinations.

  FIG. 1 is a perspective view of a battery 10 according to an embodiment of the present invention. Three arrows X, Y, and Z in FIG. 1 indicate three directions orthogonal to each other. In this embodiment, the arrow X may be referred to as the arrangement direction, the arrow Y may be referred to as the width direction, and the arrow Z may be referred to as the height direction.

  The battery 10 includes a plurality of battery cells 1 and a spacer 20 </ b> A interposed between the battery cells 1. As the battery cell 1 in the present embodiment, a secondary battery such as a lithium ion battery capable of charging and discharging electric power is preferably used. The plurality of battery cells 1 are arranged side by side in the X direction. The number of battery cells 1 can be appropriately set based on the required output of the battery 10 and the like. The battery cell 1 may be a secondary battery other than a lithium ion battery, such as a nickel metal hydride battery, a nickel cadmium battery, or a sodium sulfur battery.

  In the battery cell 1, a flat electrode winding body 3 is accommodated together with an electrolyte in a battery case 2 having a rectangular parallelepiped flat box shape. The electrode winding body 3 is configured by winding a positive electrode and a negative electrode in a flat shape with a separator interposed therebetween. For example, lithium cobaltate can be used for the positive electrode active material constituting the positive electrode, and carbon can be used for the negative electrode active material constituting the negative electrode, for example.

  The battery case 2 can be constituted by a bottomed casing formed of a metal plate such as an aluminum alloy plate into a flat rectangular parallelepiped shape by drawing or the like, and a lid member that closes the opening of the casing. The battery case 2 has a pair of wide side walls 2a and 2b facing in the arrangement direction X, a pair of narrow case side walls facing in the width direction Y, and a bottom. The pair of wide side walls 2a and 2b are flexible because they are constituted by a metal plate portion such as an aluminum alloy plate.

  In the present embodiment, the flat electrode winding body 3 housed in the battery case 2 has a winding axis O disposed along the width direction Y. Specifically, as shown by a broken line in FIG. 1, the electrode winding body 3 includes a pair of plane portions facing in the arrangement direction X as viewed from the width direction Y and heights of the pair of plane portions. It has a track shape (or an oval shape) including a pair of curved portions that are continuous at both ends in the vertical direction Z.

  A positive electrode terminal 4 and a negative electrode terminal 5 protrude from the upper surface 2c of the battery case 2 (that is, the surface of the lid member). The positive electrode terminal 4 is electrically connected to the positive electrode constituting the electrode winding body 3 in the battery case 2. The negative electrode terminal 5 is electrically connected to the negative electrode constituting the electrode winding body 3 in the battery case 2.

  In the present embodiment, the battery cells 1 adjacent to each other in the arrangement direction X are arranged such that the positive terminals 4 and the negative terminals 5 are alternately arranged in the arrangement direction X as shown in FIG. A bus bar (not shown) is connected to the positive terminal 4 of one battery cell 1 and the negative terminal 5 of the other battery cell 1 for two battery cells 1 arranged adjacent to each other. Thereby, in the battery 10 of this embodiment, all the battery cells 1 are electrically connected in series. However, the battery may include a plurality of battery cells 1 electrically connected in parallel.

  The battery 10 further includes a pair of end plates 12 a and 12 b and a restraining band 14. These end plates 12a and 12b and the restraining band 14 correspond to restraining means in the present invention. The pair of end plates 12 a and 12 b are disposed at both ends of the battery 10 in the arrangement direction X of the battery cells 1. The end plate 12 a located at one end in the arrangement direction X is arranged in contact with the battery cell 1. On the other hand, the end plate 12b located at the other end in the arrangement direction X is arranged to face the battery cell 1 via the spacer 20A. In addition, the spacer 20 </ b> A is disposed between each battery cell 1. Details of the spacer 20A will be described later.

  Two restraining bands 14 are respectively attached to the upper end surface and the lower end surface of each end plate 12a, 12b. Each constraining band 14 extends along the arrangement direction X. Both ends of each restraining band 14 are fastened to the end plates 12a and 12b by fastening members such as bolts (not shown).

  By using the end plates 12 a and 12 b and the restraining band 14, the restraining load F <b> 1 can be applied to the plurality of battery cells 1. The restraining load F1 is a force for pressing each battery cell 1 from both sides in the arrangement direction X, and is an initial load applied when the battery 10 is assembled.

  In addition, the restraining means which gives restraint load F1 with respect to the some battery cell 1 is not restricted to the structure shown in FIG. For example, the shape, the number, the arrangement position, and the like of the restraint band 14 can be changed as appropriate. Alternatively, the arranged battery cells 1 and the spacers 20A may be housed in a battery case, and a restraining load may be applied by a pair of side walls facing each other of the battery case.

  The battery 10 of this embodiment can be mounted on vehicles, such as a hybrid vehicle and an electric vehicle, for example. The hybrid vehicle is a vehicle that uses an internal combustion engine and a motor driven by electric power from the battery 10 as a power source that generates traveling energy of the vehicle. An electric vehicle is a vehicle that uses only a motor as a power source of the vehicle and uses only the battery 10 or a battery 10 and a fuel cell as an electric power source. In a vehicle equipped with the battery 10, the electric energy output from the battery 10 is converted into kinetic energy to drive the vehicle, or the kinetic energy generated during braking of the vehicle is converted into regenerative power and stored in the battery 10. be able to.

  FIG. 2A is a view schematically showing the battery cell 1 and the spacer 20A of the present embodiment as viewed from above, and FIG. 2B is a state when the battery cell and the spacer of the comparative example are viewed from above. FIG.

  As shown in FIGS. 1 and 2A, the spacer 20 </ b> A has a flat plate-like base portion 22 and a plurality of convex portions 24 a and 24 b formed to protrude from the base portion 22. The spacer 20A is integrally formed of, for example, a resin material. In this embodiment, each convex part 24a, 24b comprises the elongate rectangular parallelepiped shape extended | stretched along the height direction Z of the battery cell 1, and the front end surface contact | abutted to the side wall 2b of the battery case 2 has comprised elongate rectangular shape. Yes. Further, in the spacer 20 </ b> A, the surface of the base portion 22 that contacts the other side wall 2 a of the battery case 2 is formed to be a flat surface.

  The length in the height direction Z of the convex portions 24 a and 24 b is preferably formed to be approximately the same as the length in the height direction Z of the flat portion of the electrode winding body 3 accommodated in the battery case 2. When the battery 10 is assembled and the restraint load F1 is applied, the tip surfaces of the convex portions 24a and 24b of the spacer 20A are in contact with the outer surface of the flat side wall 2b of the battery case 2 as shown in FIG. Press in contact.

  In the spacer 20A in the present embodiment, three convex portions 24a are formed. Each convex portion 24 a is a low spring constant convex portion that contacts the side wall 2 b of the battery case 2 at a position facing the electrode winding body 3 in the battery case 2. For example, the low spring constant convex portion 24a can be realized by forming a resin material different from the convex portion 24b which is a high spring constant convex portion described later, more specifically, a resin material having a low elastic modulus. Thus, each convex part 24a which consists of a different resin material can be integrated with the base part 22 by methods, such as insert molding, adhesion | attachment, and press injection. In addition, the convex portions 24 a are arranged on the base portion 22 with an interval in the width direction X. In addition, the number of the convex parts 24a may be one or two, and may be four or more.

  On the other hand, the two protrusions 24b projecting from both ends in the width direction Y of the spacer 20A are high springs that abut against the side wall 2b of the battery case 2 at a position not facing the electrode winding body 3 in the battery case 2. It is a constant convex part. Each convex portion 24 b is integrally formed with the same resin material region as the base portion 22. Each protrusion 24b is preferably in contact with the side wall 2b at both ends of the battery case 2, that is, in the vicinity of the narrow side wall of the battery case 2.

  As a lower diagram of FIG. 2A, the surface pressure acting on the battery cell 1 is shown by the convex portions 24a and 24b, the horizontal axis represents the position in the width direction, and the vertical axis represents the surface pressure. Referring to the lower figure, when the spacer 20A of this embodiment is used, the surface pressure P1 at the position corresponding to the low spring constant convex portion 24a is kept low, and the surface at the position corresponding to the high spring constant convex portion 24b. The pressure P2 is increased (that is, P1 <P2).

  The spacer 20B of the comparative example shown in FIG. 2B shows an example in which the side wall 2b of the battery case 2 is pressed at a position facing the electrode winding body 3 by three convex portions 24c formed at intervals. It is. In this example, when the surface pressure acting on the battery case 2 by the convex portion 24c is P2, the surface pressure P3 increases when an attempt is made to secure a desired restraining load F1 for the battery cell 1.

  Compared with the surface pressures P1 and P2 due to the convex portions 24a and 24b of the spacer 20A of the present embodiment described above, a relationship of P1 <P3 <P2 is established. When the electrode winding body 3 is locally pressed through the flexible side wall 2b with such a large surface pressure P3, the surface pressure difference between the position facing the convex portion 24c and the position not facing the surface increases. In addition, the concentration of electrochemical reaction in the electrode winding body 3 occurs, and metal deposition (lithium deposition in the case of a lithium ion battery) is likely to occur.

  On the other hand, when the spacer 20A in the present embodiment is used, the flexible side wall 2b with a relatively weak surface pressure P1 at the low spring constant convex portion 24a arranged at a position facing the electrode winding body 3 is used. Since the electrode winding body 3 is pressed via the surface, the difference in surface pressure generated between the positive electrode and the negative electrode constituting the electrode winding body 3 can be reduced. As a result, metal deposition (lithium deposition in the case of a lithium ion battery) that can occur due to concentration of electrochemical reaction in the electrode winding body 3 can be suppressed. Further, by reducing the constrained area of the electrode winding body 3 by the low spring constant convex portion 24a and reducing the surface pressure, the resistance to high rate degradation that occurs when charging and discharging high power in a short time is also improved.

  On the other hand, in the spacer 20A of the present embodiment, the high spring constant convex portion 24b can firmly press the side walls 2b at both end portions in the width direction of the battery case 2 with a relatively strong surface pressure P2. Since the high spring constant convex portion 24b presses the side wall 2b of the battery case 2 at a position not facing the electrode winding body 3, it affects the positive electrode and the negative electrode constituting the electrode winding body 3 due to the difference in surface pressure. There is nothing. Therefore, if the spacer 20A of the present embodiment is used, even if the restraining load on the battery case 2 by the low spring constant convex portion 24a is low, the restraining load F1 on the battery cell 1 by the high spring constant convex portion 24b exceeds the predetermined lower limit value. Can be secured.

  Referring again to FIG. 2A, a plurality of spaces 26 are formed between the convex portions 24a and 24b of the spacer 20A. These spaces 26 can be used as flow paths for flowing a temperature adjusting medium such as air. The battery cell 1 can be cooled from the outside of the battery case 2 by flowing a temperature adjusting medium in each space 26. On the contrary, when the battery cell 1 is at a temperature lower than the proper operating temperature, the battery cell 1 can be heated by flowing heated air or the like as a temperature adjusting medium in the space 26, for example.

  FIGS. 3A to 3C are views for explaining how the spacer 20 </ b> A of the present embodiment presses the battery case 2.

  FIG. 3A is a side view when the spacer 20A is in a natural state where it is not pressed. When the spacer 20A is in a natural state and no pressing force is applied, the protruding length of the low spring constant convex portion 24a is longer than the protruding length of the high spring constant convex portion 24b by a step d. Therefore, as shown in FIG. 3B, when the spacer 20A is pressed against the side wall 2b of the battery cell 1, first, the low spring constant convex portion 24a is deformed by the collapse amount y. At this time, the high spring constant convex portion 24 b is not in contact with the side wall 2 b of the battery case 2. In this state, the restraining load exerted on the battery cell 1 by the spacer 20A can be expressed as “k2 × y” where the total spring constant of the three low spring constant protrusions 24a is k2. In this state, since the high spring constant convex portion 24b is not in contact with the battery case 2, the restraining load by the high spring constant convex portion 24b is “0”.

  Then, as shown in FIG. 3C, the crushing amount y of the convex portions 24a and 24b of the spacer 20A is further increased, and the high spring constant convex portion 24b is also pressed against the side wall 2b of the battery case 2. The restraining load by the low spring constant convex portion 24a is expressed by “k2 × y”, and when the total spring constant of the two high spring constant convex portions 24b is k1, the restraining load by the high spring constant convex portion 24b is It can be expressed as “k1 × (y−d)”. The spring constant k2 of the low spring constant convex portion 24a and the spring constant of the high spring constant convex portion 24b are set so that these total loads, that is, k1 × (y−d) + k2 × y become the above-described desired restraining load F1. k1 and the step distance d between the low spring constant convex portion 24a and the high spring constant convex portion 24b may be designed.

  The present invention is not limited to the configuration of the above-described embodiment and its modifications, and various changes and improvements can be made within the matters described in the claims of the present application and the equivalent scope thereof. is there.

  For example, although the example which comprises the low spring constant convex part 24a and the high spring constant convex part 24b of spacer 20A by using the resin material from which an elasticity modulus differs was demonstrated above, it is not limited to this. As in the spacer 20 </ b> C shown in FIG. 4A, the low spring constant convex portion 24 a may be formed in a disc spring shape or a leaf spring shape that curves and extends in the width direction. Further, like the spacer 20D shown in FIG. 4B, the base portion 23 is formed in a corrugated plate shape, and the height of, for example, three protrusions among a large number of protrusions included in the base portion 23 is increased. Thus, the low spring constant convex portion 24a may be configured.

  In the above description, an example in which the low spring constant convex portion 24a and the high spring constant convex portion 24b are provided on one surface of the base portion 22 of the spacer 20A has been described. The parts 24a and 24b may be provided.

  Furthermore, in the above description, a step d is provided between the low spring constant convex portion 24a and the high spring constant convex portion 24b so that the low spring constant convex portion 24a is crushed first, but the present invention is not limited to this. . You may comprise so that each front end surface of the low spring constant convex part 24a and the high spring constant convex part 24b may become on the same plane.

  DESCRIPTION OF SYMBOLS 1 Battery cell, 2 Battery case, 2a, 2b (Battery case side wall) 3 Electrode winding body, 4 Positive electrode terminal, 5 Negative electrode terminal, 10 Battery, 12a, 12b End plate (restraint means), 14 Restraint band (restraint) Means), 20A, 20B, 20C, 20D spacer, 22, 23 base portion, 24a low spring constant convex portion, 24b high spring constant convex portion, 26 space, d step, F1 restraining load, k1 high spring constant, k2 low spring Constant, P1, P2, P3 Surface pressure, y Crush amount.

Claims (1)

A plurality of battery cells each configured by accommodating an electrode winding body in which a positive electrode and a negative electrode are wound in a flat shape with a separator interposed therebetween in a flat box-shaped battery case;
Spacers interposed between the battery cells arranged along one direction;
A restraining means for applying a restraining load along the one direction to the plurality of battery cells and the spacer, and a battery comprising:
The battery case has a flexible side wall, the spacer includes a low spring constant convex portion and a high spring constant convex portion that abut against the side wall, and the low spring constant convex portion of the spacer is in the battery case. A high spring constant convex portion of the spacer is in contact with the side wall at a position not facing the electrode winding body in the battery case.
Battery.

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