JP2019212554A - Battery module - Google Patents

Abstract

To reduce the proportion of an elastic member in a battery module.SOLUTION: In a battery body 11 of a battery module 10, a plurality of battery cells 20 are arranged in parallel. The battery body 11 is restrained from both sides of the battery cells 20 in the juxtaposed direction by two end plates 45. In a case 21 of the battery cell 20, an elastic member 50 is juxtaposed with an electrode assembly 30 in the juxtaposed direction of the battery cells 20.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a battery module.

  The battery module includes a battery body in which a plurality of battery cells are arranged in parallel. In the battery module, it is known that a restraining load is applied to the battery body from both sides in the direction in which the battery cells are arranged in order to maintain the distance between the electrodes in the battery cell so that the resistance value of the battery cell does not increase. ing. As a configuration for applying such a restraining load, for example, a configuration in which an end plate is provided so as to sandwich the battery body from both sides in the direction in which the battery cells are arranged like the battery module described in Patent Document 1. In this battery module, the end plate is tightened with a nut or the like, whereby a restraining load is applied to the plurality of battery cells.

JP 2012-212663 A

  By the way, if a battery cell deteriorates with use, the internal pressure of a battery cell will become high. If the internal pressure of the battery cell increases, the restraint load necessary to maintain the distance between the electrodes in the battery cell is canceled out by the internal pressure of the battery cell, so that the restraint load decreases and the resistance of the battery cell may increase. is there.

  Therefore, in the direction in which the battery cells are arranged, an elastic member is provided so as to be arranged in parallel with each battery cell outside the case of each battery cell, and the distance between the electrodes in the battery cell is maintained in consideration of a rise in the internal pressure of the battery cell. It is conceivable to apply a restraint load larger than the restraint load necessary for the end plate. According to such a battery module, even if an increase in the internal pressure of the battery cell due to deterioration occurs, the restraint load necessary for maintaining the distance between the electrodes in the battery cell can be maintained, so that the resistance of the battery cell is increased. Can be suppressed.

  However, in order to improve the capacity of the battery module, it is desirable to increase the ratio of the electrode in the battery module as much as possible. In order to increase the ratio of the electrode in the battery module, it is necessary to decrease the ratio of the elastic member in the battery module.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a battery module that can further reduce the proportion of the elastic member in the battery module.

  A battery module that solves the above problems includes a battery cell in which an electrode assembly in which a positive electrode and a negative electrode are stacked and insulated is housed in a case, and a plurality of the battery cells in the stacking direction of the positive electrode and the negative electrode A battery body arranged side by side, a restraining member that restrains the battery body from both sides of the battery cell in the parallel arrangement direction, and in the case, in parallel with the electrode assembly in the parallel arrangement direction of the battery cells. And an elastic member provided.

  In general, when an elastic member such as rubber is subjected to a load from an electrode assembly or the like arranged in parallel with the elastic member, the elastic member is deformed in the acting direction of the load with a deformation amount (compression rate C) corresponding to the load. Then, a load (surface pressure P) having a magnitude corresponding to the compressibility C of the elastic member acts from the elastic member with the electrode assembly or the like arranged in parallel with the elastic member as a load target. As shown in FIG. 9, the elastic member has a characteristic that when the compressibility C becomes larger than a certain value, the surface pressure P applied to the load object from the elastic member suddenly increases. Further, even under the condition that the magnitude of the load acting on the elastic member is the same, the compression rate C of the elastic member varies depending on the degree of deterioration of the elastic member. As the deterioration of the elastic member proceeds, the compression ratio C of the elastic member increases. That is, the compression ratio C and the surface pressure P of the elastic member change within the range of the low compression ratio and the low surface pressure (for example, within the range R11) in the elastic member immediately after the start of use, but increase as the deterioration of the elastic member proceeds. It changes within the range of the compression rate and the high surface pressure (for example, within the range R13).

  Here, when the surface pressure P acting on the electrode assembly from the elastic member becomes a predetermined surface pressure P13 or more, the electrolyte solution is pushed out from between the electrodes of the battery cell, so that the resistance value of the battery cell increases. There is a fear. When the elastic member deteriorates and the compressibility C and the surface pressure P of the elastic member change within the range R13, the surface pressure P acting on the electrode assembly from the elastic member may be equal to or higher than the surface pressure P13. There is. However, in the elastic member, by increasing the size (thickness) of the elastic member in the load acting direction, the range from the low compression ratio and low surface pressure range R11 to the high compression ratio and high surface pressure range R13 is increased. Can be spread. Therefore, if the thickness of the elastic member is set large, the surface pressure P acting on the electrode assembly from the elastic member can hardly reach the surface pressure P13 even if the elastic member is further deteriorated.

  In a conventional battery module in which an elastic member is juxtaposed to each battery cell outside the case and the battery body is sandwiched by restraining members from both sides of the battery cell in the juxtaposed direction, the necessary restraint is required even if the battery cell deteriorates. In order to obtain a load, it is necessary to apply a relatively large restraining load with a restraining member in consideration of an increase in internal pressure accompanying deterioration of the battery cell. In such a conventional battery module, since the compression rate C of the elastic member is increased by receiving a large restraining load, the compression rate C and the surface pressure P of the elastic member are already relatively high immediately after the start of use of the elastic member (for example, the range). R12). With the deterioration of the elastic member, the surface pressure P acting on the electrode assembly from the elastic member relatively early may reach the surface pressure P13. For this reason, in the conventional battery module, the thickness of the elastic member in the parallel arrangement direction of the battery cells is set to be relatively large so that the surface pressure P acting on the electrode assembly from the elastic member does not reach the surface pressure P13 at an early stage. There is a need.

  On the other hand, in the battery module having the above configuration in which the elastic member is arranged in parallel with the electrode assembly in the case, even if the deterioration of the battery cell occurs and the internal pressure of the battery cell acts on the elastic member, such internal pressure is applied to the case. Can be offset by elastic deformation of the elastic member. For this reason, in the battery module having the above-described configuration, the amount of increase in the internal pressure of the battery cell considered by the constraint load can be reduced, so that the constraint load can be relatively reduced. In the battery module having such a configuration, since the compression rate C of the elastic member becomes small due to the relatively small restraint load, the compression rate C and the surface pressure P of the elastic member are relatively low immediately after the start of use of the elastic member ( For example, it changes within a range R11). And even if an elastic member deteriorates, the surface pressure P which acts on an electrode assembly from an elastic member becomes difficult to reach the said surface pressure P13 at an early stage. For this reason, in the battery module having the above configuration, the surface pressure P acting on the electrode assembly from the elastic member does not easily reach the surface pressure P13 without increasing the thickness of the elastic member in the direction in which the battery cells are arranged side by side. Can do. Therefore, in the battery module having the above configuration, the thickness of the elastic member in the direction in which the battery cells are arranged can be set smaller than that of the conventional battery module. And the ratio of the elastic member which occupies for a battery module can be made smaller by reducing the thickness of the elastic member in the parallel arrangement direction of a battery cell.

In the battery module, it is preferable that at least one of the plurality of battery cells includes the elastic member between the electrode assembly and the case.
It is also possible to provide an elastic member in the case by providing an elastic member between the electrode assemblies in the stacking direction of the electrode assembly. However, in the case where the elastic member is provided in this way, it is necessary to adjust the shape of the electrode assembly from the conventional battery cell in which the elastic member is not provided in the case. On the other hand, in the case where the elastic member is provided between the electrode assembly and the case as in the above configuration, it can be dealt with without changing the shape of the electrode assembly from the battery cell in which no elastic member is provided in the case. .

  In the battery module, the plurality of battery cells includes a first battery cell in which the elastic member is provided on one end side of the electrode assembly in the parallel arrangement direction of the battery cells, and the other end side of the electrode assembly. At least one second battery cell provided with the elastic member, and the first battery cell and the second battery cell are arranged between the elastic members in the direction in which the battery cells are arranged side by side. It is desirable that the electrode assemblies are arranged side by side so that the electrode assemblies are located.

  According to the above configuration, in the first battery cell and the second battery cell that are arranged side by side so that no elastic member is interposed between the electrode assemblies, the electrode assemblies of these battery cells serve as thermal masses. Become functional. Therefore, the heat dissipation of the first battery cell and the second battery cell can be improved.

In the battery module, it is desirable that the elastic member is bonded to the electrode assembly.
If an elastic member is bonded to the inner wall of the case, the elastic member may interfere with the electrode assembly when the electrode assembly is inserted into the case. When the elastic member interferes with the electrode assembly, the positive electrode and the negative electrode constituting the electrode assembly may be deformed. According to the above configuration, the electrode assembly can be inserted into the case with the elastic member adhered to the electrode assembly. Therefore, interference between the elastic member and the electrode assembly as described above can be suppressed.

  In the battery module, at least one of the plurality of battery cells has a first electrode assembly and a second electrode assembly arranged in the parallel arrangement direction of the battery cells as the electrode assembly. The elastic member is preferably provided between the first electrode assembly and the second electrode assembly in the direction in which the battery cells are arranged side by side.

  According to the above configuration, since there is no elastic member between the first electrode assembly and the case or between the second electrode assembly and the case in the direction in which the battery cells are arranged, these first electrode assembly and Heat radiation from the second electrode assembly to the case is facilitated. Therefore, the heat dissipation of the battery cell can be improved.

In the battery module, it is desirable that the elastic member has a maximum compressibility of 25 to 55% in the acting direction of the load when a load of 0.1 to 3.5 Mpa is applied.
If the load (surface pressure) acting on the electrode assembly from the elastic member is too small, the distance between the electrodes in the battery cell widens, thereby increasing the resistance value of the battery cell. Moreover, when the load (surface pressure) which acts on an electrode assembly from an elastic member is too large, the resistance value of a battery cell will become large because the electrolyte solution will be extruded from between electrodes. In order to avoid such an increase in the resistance value of the battery cell, it is desirable that the load acting on the electrode assembly from the elastic member is about 0.1 to 3.5 Mpa. And as an elastic member, it is desirable to employ | adopt the thing whose maximum compression rate of the effect | action direction of a load when such a load of 0.1-3.5 Mpa acts is 25-55%.

  In the battery module, it is desirable that at least one of the plurality of battery cells has a plate-like shape and has a central portion in which the thickness of the battery cells in the juxtaposition direction is smaller than the surrounding area. .

  In general, when the expansion and contraction of the electrode are repeated as the battery cell is charged and discharged, the electrolyte held between the electrodes is pushed out of the electrode assembly, so that the electrolyte between the electrodes is May decrease.

  According to the above configuration, the load acting from the elastic member is reduced at the portion of the electrode assembly that faces the central portion of the elastic member in the battery cell juxtaposition direction. Therefore, in the portion of the electrode assembly that faces the central portion, even when the electrode is repeatedly expanded and contracted, the electrolytic solution is hardly pushed out between the electrodes. Therefore, it is possible to suppress a decrease in the electrolyte solution between the electrodes due to charging / discharging of the battery cell. In addition, the center part of the said structure contains what the center of the elastic member was hollowed out besides what the center of the elastic member was formed thinly.

  According to this invention, the ratio of the elastic member to a battery module can be made smaller.

The perspective view which shows the battery module in embodiment. The disassembled perspective view which shows a battery module. The disassembled perspective view which shows an electrode assembly and an elastic member. Sectional drawing which shows a battery cell. Sectional drawing which shows a battery module. The graph which shows the characteristic of the compression rate and surface pressure of an elastic member. Sectional drawing which shows the battery cell in another embodiment. Sectional drawing which shows the battery cell in another embodiment. The graph which shows the characteristic of the compression rate and surface pressure of a general elastic member.

Hereinafter, an embodiment in which a battery module is embodied will be described with reference to FIGS.
As shown in FIG. 1 or FIG. 2, the battery module 10 includes a battery body 11 in which a plurality of battery cells 20 are arranged in the thickness direction (one direction). The direction in which the battery cells 20 are arranged side by side is referred to as a side by side arrangement. The battery cell 20 includes a bottomed square box-like case 21 and an electrode assembly 30 accommodated in the case 21. Each battery cell 20 is held by a battery holder 40.

  As shown in FIG. 2, the case 21 includes a case main body 22 and a lid 23 that closes the opening of the case main body 22. The case body 22 includes a rectangular plate-shaped bottom wall 22a, a first long side wall 22b erected from one long side edge of the pair of long side edges of the bottom wall 22a, and a pair of the bottom wall 22a. And the second long side wall 22c erected from the other long side edge of the long side edges. Further, the case body 22 includes a first short side wall 22d erected from one short side edge of the pair of short side edges of the bottom wall 22a, and a pair of short side edges of the bottom wall 22a. And the second short side wall 22e erected from the other short side edge. The battery cell 20 of the present embodiment is a rectangular battery whose appearance is a rectangular shape because the case body 22 has a bottomed square box shape and the lid 23 has a rectangular flat plate shape. Both the case main body 22 and the lid 23 are made of metal (for example, stainless steel or aluminum). Moreover, the battery cell 20 of this embodiment is a lithium ion battery.

  The battery holder 40 includes a holder main body 41 having a U-shaped frame shape and rectangular parallelepiped leg portions 42 protruding from the four corners of the outer surface of the holder main body 41. The holder main body 41 includes the bottom wall 22a of the case main body 22 of the battery cell 20, the first short side wall 22d and the second short side wall 22e, the first short side wall 22d side of the lid 23, and the second short side wall 22e of the lid 23. It is integrated with the battery cell 20 in a state of surrounding the side. For this reason, the battery cell 20 integrated with the battery holder 40 has the first long side wall 22b and the second long side wall 22c exposed from the holder body 41 to the outside. Each leg portion 42 is provided with an insertion hole 42 a penetrating in the longitudinal direction of the leg portion 42.

  As shown in FIGS. 1 and 2, end plates 45 are provided at both ends of the battery modules 10 in the juxtaposition direction. The end plate 45 includes a base portion 46 having a rectangular flat plate shape and a rectangular flat plate-like protruding portion 47 protruding from the four corners of the base portion 46. The projecting portion 47 is provided with an insertion hole 47 a penetrating in the thickness direction of the projecting portion 47.

  In the battery module 10, the bolt B <b> 1 is inserted into the insertion hole 47 a of the protrusion 47 of one end plate 45, the insertion hole 42 a of the leg 42 of each battery holder 40, and the insertion hole 47 a of the protrusion 47 of the other end plate 45. Is inserted. Then, the nut N1 is screwed into the bolt B1, whereby the two end plates 45 and the battery holders 40 are assembled together. The battery body 11 is sandwiched between two end plates 45 from both sides in the juxtaposed direction. In the present embodiment, the two end plates 45, the bolt B1, and the nut N1 function as a restraining member that restrains the battery body 11 from both sides in the juxtaposition direction. In the battery module 10, the plurality of battery cells 20 are juxtaposed with the first long side wall 22b and the second long side wall 22c aligned in one direction.

  As shown in FIG. 3, the electrode assembly 30 includes a plurality of positive electrodes 31, negative electrodes 35, and separators 39. The electrode assembly 30 has a layered structure in which separators 39 are interposed between the positive electrode 31 and the negative electrode 35 and are laminated in a mutually insulated state. A direction in which the positive electrode 31 and the negative electrode 35 are stacked is defined as a stacking direction. Moreover, each battery cell 20 is arranged in parallel along the lamination direction. For this reason, in the battery body 11 in which the plurality of battery cells 20 are arranged in parallel, the arrangement direction and the stacking direction coincide.

  The positive electrode 31 includes a rectangular sheet-like positive metal foil (for example, aluminum foil) 32 and a positive electrode active material layer 33 that exists on both surfaces of the positive metal foil 32. The positive electrode active material layer 33 is formed by applying a positive electrode active material to the positive electrode metal foil 32. Examples of the positive electrode active material include composite oxide, metallic lithium, and sulfur. The composite oxide includes at least one of manganese, nickel, cobalt, and aluminum and lithium. The positive electrode 31 includes a first edge 31a on one edge of the pair of long sides, and a second edge 31b on the other edge that is the opposite side of the first edge 31a. Prepare. Furthermore, the positive electrode 31 includes a third edge 31c on one edge of a pair of short edges connecting the first edge 31a and the second edge 31b, and a third edge. A fourth edge 31d is provided on the other edge opposite to 31c. The positive electrode 31 has a rectangular positive electrode tab 34 protruding from a part of the first edge 31a. The positive electrode tab 34 is configured by the positive electrode metal foil 32 itself without the positive electrode active material layer 33.

  The negative electrode 35 has a rectangular sheet-like negative electrode metal foil (for example, copper foil) 36 and a negative electrode active material layer 37 that is present on both surfaces of the negative electrode metal foil 36. The negative electrode active material layer 37 is formed by applying to the negative electrode metal foil 36 a negative electrode slurry containing an element capable of alloying with Li, such as silicon or tin, or a compound of these elements as a negative electrode active material. ing. The negative electrode 35 includes a first edge 35a on one edge of the pair of long edges, and a second edge 35b on the other edge opposite to the first edge 35a. Prepare. Furthermore, the negative electrode 35 includes a third edge 35c on one edge of a pair of short edges connecting the first edge 35a and the second edge 35b, and a third edge. A fourth edge 35d is provided on the other edge opposite to 35c. The negative electrode 35 has a rectangular negative electrode tab 38 protruding from a part of the first edge 35a. The negative electrode tab 38 is composed of the negative electrode metal foil 36 itself without the negative electrode active material layer 37.

  The separator 39 is made of a rectangular sheet-like insulating material. The separator 39 insulates the positive electrode 31 and the negative electrode 35 from each other. The separator 39 includes a first edge 39a on one edge of the pair of long edges, and a second edge 39b on the other edge opposite to the first edge 39a. . The separator 39 includes a third edge 39c on one edge of the pair of short sides connecting the first edge 39a and the second edge 39b, and a third edge 39c. A fourth edge 39d is provided on the other edge opposite to the other edge.

  The length of the first edge 35 a of the negative electrode 35 is longer than the length of the first edge 31 a of the positive electrode 31. The length of the second edge 35 b of the negative electrode 35 is longer than the length of the second edge 31 b of the positive electrode 31. The length of the third edge 35 c of the negative electrode 35 is longer than the length of the third edge 31 c of the positive electrode 31. The length of the fourth edge 35 d of the negative electrode 35 is longer than the length of the fourth edge 31 d of the positive electrode 31. That is, the outer shape of the negative electrode 35 is slightly larger than the outer shape of the positive electrode 31.

  The length of the first edge 39 a of the separator 39 is equal to the length of the first edge 35 a of the negative electrode 35. The length of the second edge 39 b of the separator 39 is equal to the length of the second edge 35 b of the negative electrode 35. In addition, the length of the third edge 39 c of the separator 39 is equal to the length of the third edge 35 c of the negative electrode 35. The length of the fourth edge portion 39 d of the separator 39 is equal to the length of the fourth edge portion 35 d of the negative electrode 35. That is, the outer shape of the separator 39 is slightly larger than the outer shape of the positive electrode 31, but is equal to the outer shape of the negative electrode 35.

  As shown in FIGS. 3 and 4, each positive electrode 31 is stacked such that the respective positive electrode tabs 34 are arranged in a row along the stacking direction. Similarly, each negative electrode 35 is laminated so that the respective negative electrode tabs 38 are arranged in a row along the lamination direction at positions where they do not overlap with the positive electrode tab 34. The electrode assembly 30 is insulated from the case body 22 by being covered with an insulating sheet (not shown in detail).

  As shown in FIGS. 2 and 4, the battery cell 20 includes a positive electrode terminal 25 and a negative electrode terminal 26 for taking out electricity from the electrode assembly 30. The positive terminal 25 and the negative terminal 26 pass through the through hole of the lid 23 and protrude out of the case 21. Ring-shaped insulating rings 27 for insulating from the lid 23 are attached to the positive terminal 25 and the negative terminal 26, respectively. The positive electrode tab group in which the positive electrode tabs 34 are stacked is electrically connected to the positive electrode terminal 25. The negative electrode tab group in which the negative electrode tabs 38 are laminated is electrically connected to the negative electrode terminal 26.

  As shown in FIG. 4, in the case 21, the elastic member 50 is juxtaposed with the electrode assembly 30 in the stacking direction. The elastic member 50 is made of a rectangular plate-like polyol for pre-urethane. The elastic member 50 includes a first edge 50a on one edge of the pair of long edges, and a second edge 50b on the other edge that is the opposite side of the first edge 50a. Prepare. The elastic member 50 includes a third edge 50c on one edge of the pair of short edges connecting the first edge 50a and the second edge 50b, and a third edge. A fourth edge 50d is provided on the other edge opposite to 50c.

  The length of the first edge 50 a of the elastic member 50 is equal to the length of the first edge 31 a of the positive electrode 31. The length of the second edge portion 50 b of the elastic member 50 is equal to the length of the second edge portion 31 b of the positive electrode 31. The length of the third edge 50 c of the elastic member 50 is equal to the length of the third edge 31 c of the positive electrode 31. The length of the fourth edge portion 50 d of the elastic member 50 is equal to the length of the fourth edge portion 31 d of the positive electrode 31. That is, the outer shape of the elastic member 50 is equal to the outer shape of the positive electrode 31, but is slightly smaller than the outer shape of the negative electrode 35.

  The size (thickness) of the elastic member 50 in the stacking direction is set to a size that allows a load of 0.1 to 3.5 Mpa to act on the electrode assembly 30 in the stacking direction. And as the elastic member 50, what has the maximum compression rate of the acting direction of a load when a load of 0.1-3.5 Mpa acts on the thickness direction is 25-55% is employ | adopted.

  The central part 51 located in the center of the elastic member 50 is a rectangular hole by penetrating in the thickness direction. The center portion 51 is a center C1 that is an intersection of the intermediate line L1 between the first edge portion 50a and the second edge portion 50b and the intermediate line L2 between the third edge portion 50c and the fourth edge portion 50d in the elastic member 50. Is included inside. The central portion 51 includes a first edge portion 51a on one edge portion of the edge portions along the pair of long sides, and a second edge portion on the other edge portion that is the opposite side of the first edge portion 51a. 51b. The central portion 51 includes a third edge portion 51c on one edge portion of the edge portions along the short side that connects the first edge portion 51a and the second edge portion 51b, and the third edge portion 51c. A fourth edge 51d is provided on the other edge that is the opposite side.

  The first edge 51a of the central portion 51 is located at a position shifted from the center C1 of the elastic member 50 toward the first edge 50a. Accordingly, in the elastic member 50, the length L5 from the center C1 to the first edge 51a of the central portion 51 is 15% of the length L3 from the first edge 50a to the second edge 50b of the elastic member 50. Accounted for. Further, the second edge portion 51b of the central portion 51 is located at a position shifted from the center C1 of the elastic member 50 toward the second edge portion 50b. Accordingly, in the elastic member 50, the length L6 from the center C1 to the second edge 51b of the central portion 51 is 15% of the length L3 from the first edge 50a to the second edge 50b of the elastic member 50. Accounted for.

  The third edge 51c of the central portion 51 is located at a position shifted from the center C1 of the elastic member 50 toward the third edge 50c. Accordingly, in the elastic member 50, the length L7 from the center C1 to the third edge 51c of the central portion 51 is 15% of the length L4 from the third edge 50c to the fourth edge 50d of the elastic member 50. Accounted for. Further, the fourth edge portion 51d of the central portion 51 is located at a position shifted from the center C1 of the elastic member 50 toward the fourth edge portion 50d. Accordingly, in the elastic member 50, the length L8 from the center C1 to the fourth edge 51d of the central portion 51 is 15% of the length L4 from the third edge 50c to the fourth edge 50d of the elastic member 50. Accounted for.

  As shown in FIG. 5, the elastic member 50 is provided between the end 30 a of the electrode assembly 30 and the first long side wall 22 b of the case body 22 in the stacking direction. The elastic member 50 is bonded to the end 30 a of the electrode assembly 30. In the battery cell 20, a space is defined by the central portion 51 of the elastic member 50, the end portion 30 a of the electrode assembly 30 facing the central portion 51, and the first long side wall 22 b of the case body 22.

  In the battery body 11 of the present embodiment, the plurality of battery cells 20 are arranged so that the first long side wall 22b of the case body 22 is positioned on one end side (left side in FIG. 5) of the electrode assembly 30 in the juxtaposed direction. It is installed. In such a plurality of battery cells 20, the elastic member 50 is provided on one end side of the electrode assembly 30 in the juxtaposed direction. Further, in the battery body 11 of the present embodiment, the first long side wall 22b of the case main body 22 is positioned on the other end side (right side in FIG. 5) of the electrode assembly 30 in the juxtaposed direction. It is arranged like this. In such a plurality of battery cells 20, the elastic member 50 is provided on the other end side of the electrode assembly 30 in the juxtaposed direction. Here, the battery cell 20 in which the elastic member 50 is provided on one end side of the electrode assembly 30 in the juxtaposed direction among the plurality of battery cells 20 constituting the battery body 11 is referred to as a first battery cell 20a. Among the plurality of battery cells 20 constituting the battery body 11, the battery cell 20 in which the elastic member 50 is provided on the other end side of the electrode assembly 30 in the juxtaposed direction is referred to as a second battery cell 20b.

  The battery body 11 includes a plurality of first battery cells 20a and a plurality of second battery cells 20b. That is, the elastic member 50 is juxtaposed to the electrode assembly 30 in the juxtaposition direction in the case 21 of all the battery cells 20 constituting the battery body 11. Moreover, in the battery body 11, the first battery cell 20a and the second battery cell 20b are alternately positioned. The first battery cell 20a and the second battery cell 20b are arranged in parallel so that the electrode assemblies 30 are positioned between the elastic members 50 in the juxtaposition direction in order from one end in the juxtaposition direction.

Next, the operation of the battery module 10 will be described.
As shown in FIG. 6, when a load is applied from the electrode assembly 30 to the elastic member 50, the elastic member 50 has a deformation amount (compression rate C) having a magnitude corresponding to the load and the direction of the load. Deforms in the stacking direction. Then, a load (surface pressure P) having a magnitude corresponding to the compression rate C of the elastic member 50 acts on the electrode assembly 30 from the elastic member 50. The elastic member 50 has a characteristic that the surface pressure P acting on the electrode assembly 30 from the elastic member 50 abruptly increases when the compressibility C becomes larger than a certain value. Further, even under a condition where a load having the same magnitude acts on the elastic member 50, the magnitude of the compression rate C of the elastic member 50 varies depending on the degree of deterioration of the elastic member 50. As the deterioration of the elastic member 50 progresses, the elastic member 50 has a higher compression rate C. That is, the compression rate C and the surface pressure P of the elastic member 50 change within a range R1 that is a range of a low compression rate and a low surface pressure in the elastic member 50 immediately after the start of use. Then, as the deterioration of the elastic member 50 progresses, the compression rate C and the surface pressure P of the elastic member 50 change in the range of the high compression rate side and the high surface pressure side.

  Further, if the load (surface pressure P) acting on the electrode assembly 30 in the stacking direction is too small, the distance between the positive electrode 31 and the negative electrode 35 in the battery cell 20 increases, and the resistance value of the battery cell 20 increases. turn into. In order to maintain the distance between the positive electrode 31 and the negative electrode 35 in the battery cell 20 so that the resistance value becomes a certain value or less, the electrode assembly 30 is given a surface pressure P of 0.1 Mpa or more in the stacking direction. It is desirable to act. Note that the internal pressure of the battery cell 20 increases due to expansion / contraction and deterioration associated with charging / discharging of the battery cell 20, but the elastic member 50 is elastically deformed in response to the increase in internal pressure, whereby the electrode assembly 30 includes the elastic member 50. Therefore, the surface pressure P of 0.1 Mpa or more acts. Specifically, when the deterioration of the elastic member 50 is not progressing so much, the surface pressure P changes in the range R1, and thus the surface pressure P becomes greater than 0.1 Mpa. And as the deterioration of the elastic member 50 progresses, the surface pressure P changes in the range on the high surface pressure side, so the surface pressure P further increases. Therefore, even if the internal pressure of the battery cell 20 changes, a load appropriate to maintain the distance between the positive electrode 31 and the negative electrode 35 in the electrode assembly 30 acts on the electrode assembly 30 from the elastic member 50.

  On the other hand, if the load (surface pressure P) acting on the electrode assembly 30 in the stacking direction is too large, the electrolyte solution is pushed out from between the positive electrode 31 and the negative electrode 35, so that the resistance value of the battery cell 20 is May grow. Specifically, if the surface pressure P acting on the electrode assembly 30 in the stacking direction is greater than 3.5 Mpa, the resistance value of the battery cell 20 may increase. In the elastic member 50, even if the elastic member 50 is deteriorated, it is possible to suppress such an excessive load from acting on the electrode assembly 30. The elastic member 50 functions as an elastic member 50 with an elastic member having a maximum compression rate C3 of 25 to 55% in the acting direction of the load when a load of 0.1 to 3.5 Mpa is applied to the elastic member 50. It is possible by using it. In the elastic member 50, a surface pressure P of 3.5 Mpa acts on the electrode assembly 30 when the maximum compression rate C3 is reached.

In the above embodiment, the following effects can be obtained.
(1) In the battery module 10 of the above embodiment in which the elastic member 50 is arranged in parallel with the electrode assembly 30 in the case 21, the battery cell 20 is deteriorated so that the internal pressure of the battery cell 20 acts on the elastic member 50. Even in this case, the internal pressure can be offset by elastic deformation of the elastic member 50 in the case 21. Therefore, in the battery module 10, since the increase in the internal pressure of the battery cell 20 considered by the restraint load can be reduced, the restraint load can be made relatively small. In the battery module 10, the compression rate C of the elastic member 50 is reduced by receiving a relatively small restraining load. Therefore, the compression rate C and the surface pressure P of the elastic member 50 are relatively low immediately after the start of use of the elastic member 50. It changes in. Even if the elastic member 50 is deteriorated, the surface pressure P acting on the electrode assembly 30 from the elastic member 50 is excessive so as to push out the electrolyte from between the positive electrode 31 and the negative electrode 35 of the battery cell 20. It becomes difficult to reach even the surface pressure. For this reason, in the battery module 10, even if the thickness of the elastic member 50 is not increased, the surface pressure P acting on the electrode assembly 30 from the elastic member 50 can be less likely to reach the excessive surface pressure. Therefore, in the battery module 10, the proportion of the elastic member 50 in the battery module 10 can be further reduced by reducing the thickness of the elastic member 50 in the juxtaposed direction.

  (2) It is possible to provide the elastic member 50 in the case 21 by providing the elastic member 50 between the electrode assemblies 30 in the stacking direction. However, when the elastic member 50 is provided in this way, it is necessary to adjust the shape of the electrode assembly 30 from the conventional battery cell 20 in which the elastic member 50 is not provided in the case 21. For example, since the positions of the positive electrode 31 and the negative electrode 35 in the stacking direction are shifted by the amount of the elastic member 50 interposed therebetween, the positional relationship between the positive electrode terminal 25 and each positive electrode 31 and the position between the negative electrode terminal 26 and each negative electrode 35. The relationship is off. Therefore, there is a possibility that a large change in the electrode assembly 30 may be required, such as increasing the protruding length of the positive electrode tab 34 of the positive electrode 31 and the negative electrode tab 38 of the negative electrode 35 in accordance with such deviation. On the other hand, when the elastic member 50 is provided between the electrode assembly 30 and the case body 22 as in the above embodiment, the shape of the electrode assembly 30 from the conventional battery cell 20 in which the elastic member 50 is not provided in the case 21. It is possible to cope without changing.

  (3) In the first battery cell 20a and the second battery cell 20b arranged in parallel so that the elastic member 50 is not interposed between the electrode assemblies 30, the electrode assemblies 30 function as a thermal mass. It becomes like this. Therefore, the heat dissipation of the first battery cell 20a and the second battery cell 20b can be improved. For example, when one of the first battery cell 20a and the second battery cell 20b generates heat due to a battery cell abnormality or the like, the electrode assembly 30 of the other battery cell functions as a thermal mass and is generated. Heat can be dissipated.

  (4) If the elastic member 50 is bonded to the inner wall of the first long side wall 22 b of the case body 22, the elastic member 50 is inserted into the case body 22 when the electrode assembly 30 is inserted into the case body 22. There is a risk of interference. When the elastic member 50 interferes with the electrode assembly 30, the positive electrode 31 and the negative electrode 35 constituting the electrode assembly 30 may be deformed. According to the above embodiment, the electrode assembly 30 can be inserted into the case main body 22 with the elastic member 50 adhered to the electrode assembly 30. Therefore, interference between the elastic member 50 and the electrode assembly 30 as described above can be suppressed.

  (5) In general, when the positive electrode 31 and the negative electrode 35 are repeatedly expanded and contracted as the battery cell 20 is charged / discharged, the electrolytic solution held between the positive electrode 31 and the negative electrode 35 becomes the electrode. By being pushed out of the assembly 30, the electrolyte solution between the positive electrode 31 and the negative electrode 35 may be reduced. In the above embodiment, no load is applied from the elastic member 50 to a portion of the electrode assembly 30 that faces the central portion 51 of the elastic member 50 in the juxtaposed direction. Therefore, in the portion facing the central portion 51 in the electrode assembly 30, even when the positive electrode 31 and the negative electrode 35 are repeatedly expanded and contracted, the electrolyte is pushed out between the positive electrode 31 and the negative electrode 35. It becomes difficult. Therefore, it is possible to suppress a decrease in the electrolyte solution between the positive electrode 31 and the negative electrode 35 due to charging / discharging of the battery cell 20. Moreover, in the said embodiment, electrolyte solution can be hold | maintained in the space formed by the center part 51 of the elastic member 50, and the electrode assembly 30 facing this center part 51. FIG. For this reason, when the electrolytic solution is pushed out from between the positive electrode 31 and the negative electrode 35 along with charging / discharging of the battery cell 20, the electrolytic solution is supplied from the above space to between the positive electrode 31 and the negative electrode 35. can do. In this respect as well, it is possible to suppress a decrease in the electrolytic solution between the positive electrode 31 and the negative electrode 35 due to charging / discharging of the battery cell 20.

  (6) In this embodiment that employs a negative electrode active material containing an element that can be alloyed with Li, such as silicon or tin, or a compound of those elements, when only another negative electrode active material such as graphite is employed As compared with the above, the amount of expansion and contraction of the negative electrode 35 accompanying charge / discharge increases. If the restraint load is set large in consideration of the expansion amount of the negative electrode 35, it is necessary to increase the thickness of the elastic member 50 in accordance with the restraint load. However, in the above embodiment, by providing the elastic member 50 in the case 21, the expansion of the negative electrode 35 can be offset by the elastic deformation of the elastic member 50 in the case 21. For this reason, the restraining load can be made relatively small so as not to consider the expansion amount of the negative electrode 35, and the thickness of the elastic member 50 can be reduced. Therefore, the proportion of the elastic member 50 in the battery module 10 can be reduced. .

  In addition, the said embodiment can be changed and implemented as follows. The above embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.

  (Circle) the 1st battery cell 20a and the 2nd battery cell 20b may be located so that the some 1st battery cell 20a may continue in a part of juxtaposition direction. Moreover, the 1st battery cell 20a and the 2nd battery cell 20b may be located so that the 2nd battery cell 20b may continue in a part of parallel arrangement direction.

  As shown in FIG. 7, in the same battery cell 120, between the end 30 a of the electrode assembly 30 and the first long side wall 22 b of the case body 22, and on the side opposite to the end 30 a of the electrode assembly 30. The elastic member 50 may be provided on both the end 30b of the case and the second long side wall 22c of the case body 22. In the battery cell 120 in this embodiment, two elastic members 50 are provided in the case 21. Therefore, the thickness of each elastic member 50 in the battery cell 120 is appropriately adjusted to about half the thickness of the elastic member 50 provided in the first battery cell 20a or the second battery cell 20b in the above embodiment.

  As shown in FIG. 8, the battery cell 220 may include a first electrode assembly 230 and a second electrode assembly 231 arranged in the juxtaposed direction as the electrode assembly 30. In the first electrode assembly 230 and the second electrode assembly 231, the positive electrode tab 34 of each positive electrode 31 is electrically connected to the same positive electrode terminal 25 and the negative electrode tab 38 of each negative electrode 35. Are electrically connected to the same negative terminal 26. In the battery cell 220, the elastic member 50 may be provided between the first electrode assembly 230 and the second electrode assembly 231 in the juxtaposed direction. In the battery cell 220 of this embodiment, between the first electrode assembly 230 and the first long side wall 22b of the case body 22, or between the second electrode assembly 231 and the second long side wall 22c of the case body 22. The elastic member 50 is not provided. Therefore, heat can be easily radiated from the first electrode assembly 230 and the second electrode assembly 231 to the case body 22. Therefore, the heat dissipation of the battery cell 220 can be improved.

  The battery body 11 may be configured by only one type of battery cell 20 among the first battery cell 20a, the second battery cell 20b, the battery cell 120, and the battery cell 220. You may comprise the battery body 11 combining 2 or more types of battery cells 20 among the 1st battery cell 20a, the 2nd battery cell 20b, the battery cell 120, and the battery cell 220. FIG.

  ○ The size of the central portion 51 can be changed as appropriate. Specifically, the ratio of the length L5 of the central portion 51 to the length L3 of the elastic member 50 can be changed within a range of 12 to 25%. The ratio of the length L6 of the central portion 51 to the length L3 of the elastic member 50 can be changed within a range of 12 to 25%. The ratio of the length L7 of the central portion 51 to the length L4 of the elastic member 50 can be changed within a range of 10 to 18%. The ratio of the length L8 of the central portion 51 to the length L4 of the elastic member 50 can be changed within a range of 10 to 18%.

The central part 51 of the elastic member 50 may not be a hole but may have a thin shape whose thickness is smaller than the thickness of a part other than the central part 51.
The formation of the central portion 51 may be omitted in some or all of the elastic members 50 of all the battery cells 20 constituting the battery body 11.

The elastic member 50 may not be bonded to the electrode assembly 30. For example, the elastic member 50 may be bonded to the inner walls of the first long side wall 22b and the second long side wall 22c of the case body 22.
○ When the surface pressure P appropriate for acting on the electrode assembly 30 is deviated from 0.1 to 3.5 Mpa due to the shape change of the battery module 10 or the like, the thickness of the elastic member 50 according to the surface pressure P Can be appropriately changed. Moreover, the elastic member 50 is not restricted to the thing whose maximum compression rate C3 of the acting direction of a load is 25 to 55%.

The elastic member 50 may be made of a material other than a polyol for pre-urethane, such as polypropylene or polyethylene.
The negative electrode active material layer 37 includes a negative electrode active material other than carbon, such as graphite, a metal compound, boron-added carbon, or the like, an element capable of alloying with Li, such as silicon or tin, or a compound of these elements. But you can.

On both sides of the negative electrode metal foil 36 of the negative electrode 35, there may be a portion where the negative electrode active material layer 37 is not formed.
O On both surfaces of the positive electrode metal foil 32 of the positive electrode 31, there may be a portion where the positive electrode active material layer 33 is not formed.

  The elastic member 50 may be larger than the positive electrode 31 such as the same size as the negative electrode 35 or may be smaller than the positive electrode 31. 80% or more of the positive electrode active material layer 33 of the positive electrode 31 by the entire elastic member 50 (when the central portion 51 is formed on the elastic member 50, the entire elastic member 50 including the portion where the central portion 51 is formed). It is preferable to set the size of the elastic member 50 so that it can be covered.

The elastic member 50 may have a shape other than a plate shape such as a spring shape.
The separator 39 may be formed slightly larger than the negative electrode 35.
○ The battery holder 40 may be omitted.

  The battery cell 20 is not limited to a lithium ion battery but may be a nickel metal hydride battery or an electric double layer capacitor.

  B1 ... bolt, N1 ... nut, 10 ... battery module, 11 ... battery body, 20, 120, 220 ... battery cell, 20a ... first battery cell, 20b ... second battery cell, 21 ... case, 30 ... electrode assembly , 31 ... positive electrode, 35 ... negative electrode, 39 ... separator, 45 ... end plate, 50 ... elastic member, 51 ... central part, 230 ... first electrode assembly, 231 ... second electrode assembly.

Claims (7)

A battery cell in which an electrode assembly in which a positive electrode and a negative electrode are insulated and stacked is housed in a case;
A battery body in which a plurality of the battery cells are arranged in parallel in the stacking direction of the positive electrode and the negative electrode,
A restraining member that restrains the battery body from both sides of the battery cells in the juxtaposed direction;
A battery module, comprising: an elastic member provided in the case and arranged in parallel with the electrode assembly in a direction in which the battery cells are arranged in parallel.   The battery module according to claim 1, wherein at least one of the plurality of battery cells is provided with the elastic member between the electrode assembly and the case. The plurality of battery cells include a first battery cell in which the elastic member is provided on one end side of the electrode assembly and an elastic member on the other end side of the electrode assembly in the parallel arrangement direction of the battery cells. Including at least one second battery cell provided,
The said 1st battery cell and the said 2nd battery cell are arranged in parallel so that the said electrode assembly may mutually be located between the said elastic members in the arrangement direction of the said battery cell. Battery module.   The battery module according to claim 2, wherein the elastic member is bonded to the electrode assembly. At least one battery cell among the plurality of battery cells has, as the electrode assembly, a first electrode assembly and a second electrode assembly arranged in a parallel arrangement direction of the battery cells,
The battery module according to claim 1, wherein the elastic member is provided between the first electrode assembly and the second electrode assembly in a direction in which the battery cells are arranged side by side.   The battery according to any one of claims 1 to 5, wherein the elastic member has a maximum compressibility of 25 to 55% in a direction in which a load acts when a load of 0.1 to 3.5 Mpa is applied. module. The at least one elastic member among the plurality of battery cells is plate-shaped, and includes a central portion in which the thickness in the juxtaposed direction of the battery cells is smaller than the surroundings. The battery module as described in any one.