JP2020064792A - Power storage device - Google Patents

Abstract

To provide a power storage device capable of improving insulation between a tab group of an electrode assembly and a case.SOLUTION: A power storage device 10 comprises an electrode assembly 20, a case 30, and an insulation sheet 40. The insulation sheet 40 comprises: a pair of end face covering parts 41, 41; a pair of side face covering parts 43, 43; and sticking-out parts 44 disposed so as to surround a positive electrode tab group 24 and a negative electrode tab group 25. In a state in which the electrode assembly 20 is covered with the insulation sheet 40, two ridge-folding parts 50 are formed so as to extend in a protrusion direction and be positioned outside the respective tab groups 24, 25 in a direction orthogonal to a lamination direction X and the protrusion direction, on each of the sticking-out parts 44 contiguous to the pair of end face covering parts 41, 41. Apexes T extending along the protrusion direction of the two ridge-folding parts 50 are disposed at positions apart from both end faces of the electrode assembly 20 in the lamination direction X.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device.

  BACKGROUND ART Conventionally, there is known a power storage device configured by housing an electrode assembly in a case (see Patent Document 1). The electrode assembly is layered by stacking a positive electrode and a negative electrode. The electrode assembly is provided with a tab group on one end face in the stacking direction. The tab group extends in a direction orthogonal to the stacking direction. The tab group is provided with a conductive member that connects the same polarities. The case includes a bottomed cylindrical main body member that houses the electrode assembly, and a lid member that is provided so as to close the opening of the main body member. The lid member is welded to the main body member.

  The power storage device includes an insulating sheet that insulates between the electrode assembly and the case. The insulating sheet has a box shape that covers the electrode assembly. The insulating sheet includes a pair of end surface covering portions that cover both end surfaces of the electrode assembly in the stacking direction, a bottom surface covering portion that covers the other end surface of the electrode assembly opposite the one end surface, and both end surfaces of the electrode assembly stacking direction. And a pair of side surface covering portions that cover both side surfaces of the electrode assembly orthogonal to one end surface of the electrode assembly. Further, the insulating sheet has a protruding portion protruding from one end surface of the electrode assembly in the protruding direction of the tab group. The protruding portion is continuous with the pair of end surface covering portions and the pair of side surface covering portions, and is arranged so as to surround the tab group and the conductive member, thereby improving the insulating property between the electrode assembly and the case. .

Japanese Patent No. 6314086

  By the way, in a state where the electrode assembly and the insulating sheet are housed in the case, the protruding portion of the insulating sheet extends to the vicinity of the boundary between the main body member and the lid member of the case. When the main body member and the lid member are welded in this state, the insulating sheet may be melted. At this time, for example, if a portion of the protruding portion facing the tab group of the electrode assembly in the stacking direction is melted, a short circuit may occur between the tab group of the electrode assembly and the case.

  The present invention has been made by paying attention to the problems existing in such a conventional technique, and an object thereof is to provide a power storage device capable of improving insulation between a tab group and a case of an electrode assembly. Is to provide.

  In a power storage device that solves the above problems, a positive electrode and a negative electrode are stacked, and an electrode assembly in which a tab group extends in a direction orthogonal to the stacking direction on one end face in the stacking direction and the electrode assembly is housed. A bottomed tubular main body member, a lid member provided so as to close the opening of the main body member, and a case having a welded portion where the main body member and the lid member are welded, and the electrode assembly And an insulating sheet provided between the case and the case to insulate the electrode assembly from the case, wherein the insulating sheets are both ends of the electrode assembly in the stacking direction. A pair of end surface covering portions for covering the surfaces, a pair of side surface covering portions for covering both end surfaces of the electrode assembly orthogonal to the both end surfaces of the electrode assembly and the one end surface of the electrode assembly, and the pair of side surface covering portions. The end face coating portion and the pair of The electrode assembly, which is continuous with the surface covering portion and extends toward the protruding direction of the tab group along the both end surfaces of the electrode assembly so as to surround the tab group. In a state in which a three-dimensional object is covered with the insulating sheet, each of the protruding portions continuous with the pair of end surface covering portions extends along the protruding direction, and in the stacking direction and the direction orthogonal to the protruding direction, Two mountain folds are formed so as to be located outside the tab group, and the tops of the two mountain folds extending along the protruding direction are separated from the both end surfaces of the electrode assembly in the stacking direction. It is located in the position

  According to this, it is difficult for the tops of the two mountain folds of the protruding portion to return to the tab group of the electrode assembly in the stacking direction. Therefore, the tops of the two mountain folds are easily held at positions separated from both end surfaces of the electrode assembly. Further, the two mountain folds of the protruding portion are provided so as to sandwich the portion of the protruding portion facing the tab group in the direction orthogonal to the stacking direction and the protruding direction. That is, the portion of the protruding portion facing the tab group is easily held at a position close to the tab group by forming the two mountain folds.

  When welding the lid member and the main body member with the electrode assembly and the insulating sheet accommodated in the main body member, the mountain fold portion of the protruding portion of the insulating sheet may melt. However, the portion of the protruding portion facing the tab group is easily held in a state of being separated from the inner surface of the main body member by the mountain fold portion of the protruding portion. Therefore, the insulation between the tab group of the electrode assembly and the case can be improved.

  In a power storage device that solves the above problems, a positive electrode and a negative electrode are stacked, and an electrode assembly in which a tab group extends in a direction orthogonal to the stacking direction on one end face in the stacking direction and the electrode assembly is housed. A bottomed tubular main body member, a lid member provided so as to close the opening of the main body member, and a case having a welded portion where the main body member and the lid member are welded, and the electrode assembly And an insulating sheet provided between the case and the case to insulate the electrode assembly from the case, wherein the insulating sheets are both ends of the electrode assembly in the stacking direction. A pair of end surface covering portions covering the surfaces, a pair of side surface covering portions covering both end surfaces of the electrode assembly and both side surfaces of the electrode assembly orthogonal to the one end surface of the electrode assembly, and the pair of side surface covering portions. The end face coating portion and the pair of The electrode assembly, which is continuous with the surface covering portion and extends toward the protruding direction of the tab group along the both end surfaces of the electrode assembly so as to surround the tab group. In a state in which a three-dimensional object is covered with the insulating sheet, one of the protruding portions continuous with the pair of end surface covering portions extends along the protruding direction, and in the stacking direction and the direction orthogonal to the protruding direction, Two mountain folds are formed so as to be located outside the tab group, and the main body member and the tab group are provided between the tab group and the other of the protruding portions that are continuous with the pair of end surface covering portions. An insulating member is provided to insulate between and.

  According to this, by forming the two mountain folds provided on one of the protruding portions that are continuous with the pair of end surface covering portions of the insulating sheet, one of the portions of the protruding portion that faces the tab group is It is easy to hold the tabs close to them. Further, an insulating member is provided between the tab group and the other of the protruding portions continuous with the pair of end surface covering portions. Therefore, even if the other portion of the protruding portion facing the tab group is melted, the insulating member can insulate the case from the tab group. Therefore, the insulation between the tab group of the electrode assembly and the case can be improved.

  In the above power storage device, the tab group includes a positive electrode tab group and a negative electrode tab group formed by stacking tabs of the same polarity formed on the positive electrode and the negative electrode, and the two mountain folds are formed. Is preferably formed so as to be located outside each of the positive electrode tab group and the negative electrode tab group in the direction orthogonal to the stacking direction and the projecting direction.

According to this, the two mountain folds can suppress the melting of the portions of the protruding portion that face the positive electrode tab group and the negative electrode tab group, respectively.
In the above power storage device, the insulating sheet has a bottom surface covering portion that covers the other end surface of the electrode assembly opposite to the one end surface, and in a state where the insulating sheet is expanded, the insulating sheet has a rectangular shape. The bottom surface covering portion having a shape, which is sandwiched between the pair of end surface covering portions and the pair of end surface covering portions and which is continuous with the pair of end surface covering portions via the first boundary line and the second boundary line. A base portion having, and a pair of side surface covering portions that sandwich the base portion and are continuous with the base portion via a third boundary line and a fourth boundary line orthogonal to the first boundary line and the second boundary line, And an extension portion that is continuous with the base portion and the pair of side surface coating portions and that has the protrusion portion that extends toward the outer periphery of the insulating sheet, and from the state of covering the electrode assembly. Previous When the insulating sheet is unfolded, the base portion and the protruding portion of the insulating sheet, when viewed from the side opposite to the mounting surface on which the other end surface of the electrode assembly in the bottom surface covering portion is mounted, Two mountain fold lines parallel to the third boundary line and the fourth boundary line may be formed along the tops of the two mountain fold portions.

  According to this, when the electrode assembly is covered with the insulating sheet, the mountain folds are formed not only on the protruding portion but also on the pair of end face covering portions. Compared with the case where the mountain folds are formed only in the protruding portions, the tops of the mountain folds in the protruding portions are more difficult to return to the tab group of the electrode assembly in the stacking direction. Therefore, the mountain fold portion of the protruding portion is more likely to be held by being protruded toward the inner side surface of the main body member than the portion of the protruding portion where the tab groups face each other. Therefore, it is possible to further suppress melting of the portion of the protruding portion of the insulating sheet that faces the tab group of the electrode assembly.

  According to the present invention, it is possible to suppress the melting of the facing portion facing the tab group of the electrode assembly in the protruding portion of the insulating sheet.

FIG. 3 is a perspective view of the power storage device according to the first embodiment. The exploded perspective view of an electrode assembly. FIG. 3 is an exploded perspective view of a power storage device. The front view which shows the expansion | deployment shape of an insulating sheet. Sectional drawing in 2nd Embodiment of an electrical storage apparatus. The perspective view of the electrical storage device in a modification.

<First Embodiment>
Hereinafter, a first embodiment that embodies a power storage device will be described with reference to FIGS. 1 to 4. The power storage device of this embodiment is mounted on a vehicle (automobile and industrial vehicle) and is used to drive a traveling motor mounted on the vehicle.

  As shown in FIG. 1, power storage device 10 is a lithium-ion secondary battery. The power storage device 10 includes an electrode assembly 20, a case 30, and an insulating sheet 40. The case 30 accommodates the electrode assembly 20 and the insulating sheet 40. The insulating sheet 40 has a box shape that covers the electrode assembly 20. The insulating sheet 40 is provided so as to cover the electrode assembly 20 and insulates the electrode assembly 20 and the case 30 from each other. The insulating sheet 40 is made of resin or the like.

  As shown in FIGS. 1 and 2, the electrode assembly 20 is formed into a rectangular prism shape by laminating a plurality of sheet-shaped positive electrodes 21 and a plurality of sheet-shaped negative electrodes 22. The electrode assembly 20 is configured by sandwiching a separator 23 between a positive electrode 21 and a negative electrode 22. The separator 23 is formed of a porous film through which ions for electric conduction (lithium ions) can pass. The electrode assembly 20 includes a positive electrode tab group 24 and a negative electrode tab group 25 on one end surface S2. The positive electrode tab group 24 and the negative electrode tab group 25 are configured by stacking tabs 24a and 25a of the same polarity formed on the electrodes 21 and 22, respectively. The positive electrode tab group 24 and the negative electrode tab group 25 extend from one end surface S2 of the electrode assembly 20 in the stacking direction X in a direction orthogonal to the stacking direction X. The positive electrode tab group 24 and the negative electrode tab group 25 are connected to the positive electrode terminal 26 and the negative electrode terminal 27, which are accessible from the outside of the case 30, and the positive electrode conductivity that connects the terminals 26, 27 and the tab groups 24, 25 with the same polarity. The member 28 and the negative electrode conductive member 29 are connected.

  As shown in FIG. 1, the case 30 has a main body member 31 and a lid member 32. The body member 31 has a bottomed tubular shape. The body member 31 houses the electrode assembly 20. The main body member 31 has an internal space formed in a rectangular tube shape corresponding to the electrode assembly 20 having a rectangular column shape. The size of the main body member 31 is set to such a degree that a predetermined gap is formed between the body member 31 and the outer surface of the electrode assembly 20 when the electrode assembly 20 is housed in the internal space. The lid member 32 is provided so as to close the opening 31 a of the main body member 31. The lid member 32 is welded to the opening 31 a of the main body member 31. A welded portion of the boundary portion between the main body member 31 and the lid member 32 is referred to as a welded portion 33. With the lid member 32 welded to the main body member 31, the terminals 26 and 27 of the electrode assembly 20 penetrate the lid member 32 and are exposed to the outside of the case 30. At this time, an insulating ring 80 is provided between each terminal 26, 27 and the lid member 32. The insulating ring 80 penetrates the lid member 32 and is located inside and outside the case 30. By providing the insulating ring 80, insulation between the terminals 26 and 27 of the electrode assembly 20 and the lid member 32 of the case 30 is ensured.

  As shown in FIGS. 1 and 3, the insulating sheet 40 includes a pair of end surface coating portions 41, 41, a bottom surface coating portion 42, and a pair of side surface coating portions 43, 43. The pair of end surface coating portions 41, 41 are portions that cover both end surfaces S1 of the electrode assembly 20 in the stacking direction X. The bottom surface covering portion 42 is a portion that covers the other end surface S3 of the electrode assembly 20 opposite to the one end surface S2. The pair of side surface covering portions 43, 43 are portions that cover both side surfaces S4 of the electrode assembly 20 orthogonal to both end surfaces S1 of the electrode assembly 20 and one end surface S2 of the electrode assembly 20. The insulating sheet 40 also includes a protruding portion 44 that is continuous with the pair of end surface coating portions 41, 41 and the pair of side surface coating portions 43, 43. The protruding portion 44 extends in the protruding direction of the positive electrode tab group 24 and the negative electrode tab group 25 along both end surfaces S1 of the electrode assembly 20. The protruding portion 44 is arranged so as to surround the positive electrode tab group 24, the negative electrode tab group 25, the positive electrode conductive member 28, and the negative electrode conductive member 29.

  In a state where the electrode assembly 20 is covered with the insulating sheet 40, the pair of end surface covering portions 41, 41 of the insulating sheet 40 and the protruding portion 44 continuous with the pair of end surface covering portions 41, 41 respectively have two ridges. Two sets of folding parts 50 are formed. The two mountain folds 50 extend in the protruding direction of the positive electrode tab group 24 and the negative electrode tab group 25 along both end surfaces S1 of the electrode assembly 20. The two mountain folds 50 are formed so as to be located outside the positive electrode tab group 24 and the negative electrode tab group 25 in the direction orthogonal to the stacking direction X and the projecting direction. That is, the positive electrode facing portion 45 a of the protruding portion 44 facing the positive electrode tab group 24 and the negative electrode facing portion 45 b of the protruding portion 44 facing the negative electrode tab group 25 are sandwiched by the two mountain fold portions 50. . Each of the two mountain folds 50 has a top T extending along the protruding direction. The tops T of the two mountain folds 50 are arranged at positions separated from both end surfaces S1 of the electrode assembly 20 in the stacking direction X. The tops T of the two mountain folds 50 are in contact with the inner surface of the body member 31 of the case 30. The positive electrode facing portion 45a and the negative electrode facing portion 45b are separated from the inner surface of the main body member 31 of the case 30 in the stacking direction X and are arranged near the positive electrode tab group 24 and the negative electrode tab group 25 of the electrode assembly 20.

  As shown in FIG. 4, in a state where the insulating sheet 40 is unfolded, the insulating sheet 40 has a base portion 61 formed in a rectangular shape and an extension extending from the base portion 61 toward the outer periphery of the insulating sheet 40. The projection 62 is formed, and has a long rectangular shape (rectangular shape) as a whole. The base portion 61 is composed of a pair of end surface covering portions 41, 41 and a bottom surface covering portion 42. The pair of end surface covering portions 41, 41 and the bottom surface covering portion 42 are continuous in the long side direction of the insulating sheet 40. The bottom surface covering portion 42 is sandwiched between the pair of end surface covering portions 41, 41. The pair of end surface covering portions 41, 41 and the bottom surface covering portion 42 are continuous via a first boundary line B1 and a second boundary line B2. The extending portion 62 is composed of a pair of side surface covering portions 43, 43 and a protruding portion 44. The pair of side surface covering portions 43, 43 and the base portion 61 are continuous in the short side direction of the insulating sheet 40. The base portion 61 is sandwiched between the pair of side surface covering portions 43, 43. The pair of side surface covering portions 43, 43 and the base portion 61 are continuous with each other through a third boundary line B3 and a fourth boundary line B4 which are orthogonal to the boundary lines B1, B2. The protruding portion 44 is continuous with the base portion 61 and the pair of side surface covering portions 43, 43, and extends toward the outer periphery of the insulating sheet 40. The protruding portion 44 extends from the short side of the base portion 61 and the short sides of the pair of side surface covering portions 43, 43 toward the long side direction of the insulating sheet 40. The pair of side surface covering portions 43, 43 are divided into three continuous parts by extension lines of the first boundary line B1 and the second boundary line B2. The three parts include a pair of first parts 43a and 43a that are continuous with one short side of the pair of end surface covering portions 41 and 41, and a pair of first parts that are continuous with the other short side of the pair of end surface covering portions 41 and 41. It is composed of two parts 43b, 43b and a pair of third parts 43c, 43c continuous with the short side of the bottom surface covering portion 42. When the electrode assembly 20 is covered with the insulating sheet 40 configured as described above, the insulating sheet 40 bends the boundary lines B1 and B2 so that both end surfaces S1 of the electrode assembly 20 are covered with a pair of end surface covering portions 41 and 41. Then, the boundary lines B3 and B4 are bent to cover the side surfaces S4 of the electrode assembly 20 with the pair of side surface covering portions 43 and 43.

  As shown in FIGS. 1 and 4, in the state where the electrode assembly 20 is covered with the insulating sheet 40, the pair of side surface covering portions 43, 43 has the third part 43c arranged in the outermost layer and the first part 43a. , The second part 43b, and a part of the third part 43c overlap each other. By forming the side surface covering portion 43 by the first part 43a, the second part 43b, and the third part 43c, the boundary lines B1, B2, B3, and B3 are formed on the insulating sheet 40 in the expanded state of the insulating sheet 40. A fold line J is formed extending obliquely so as to be separated from each of the right-angled intersections Pr, starting from the four right-angled intersections Pr of which B4 are orthogonal to each other.

  As shown in FIG. 4, when the insulating sheet 40 is unfolded from the state of covering the electrode assembly 20, the base portion 61 and the protruding portion 44 of the insulating sheet 40 have an electrode assembly in the bottom cover portion 42 of the insulating sheet 40. Two sets of two mountain fold lines Lm are formed when viewed from the side opposite to the placement surface 42a (the front side of the paper surface of FIG. 4) on which the other end surface S3 of the three-dimensional body 20 is placed. The two mountain fold lines Lm are parallel to the third boundary line B3 and the fourth boundary line B4 along the tops T of the two mountain fold portions 50. One of the two sets of two mountain fold lines Lm is arranged so as to sandwich the positive electrode facing portion 45a of the protruding portion 44 in the short side direction of the insulating sheet 40. The remaining one set of the two sets of the two mountain fold lines Lm is arranged so as to sandwich the negative electrode facing portion 45b of the protruding portion 44 in the short side direction of the insulating sheet 40.

Here, the order of bending the insulating sheet 40 will be described.
As shown in FIGS. 1 and 4, first, two sets of two mountain fold lines Lm are formed on the expanded insulating sheet 40. In this state, the mounting surface 42a of the bottom surface covering portion 42 of the insulating sheet 40 in which two sets of two mountain fold lines Lm are formed and the other end surface S3 of the electrode assembly 20 are arranged to overlap each other, The insulating sheet 40 is bent along the first boundary line B1 and the second boundary line B2. As a result, both end surfaces S1 of the electrode assembly 20 in the stacking direction X are covered with the pair of end surface covering portions 41, 41.

  Next, the insulating sheet 40 is bent along the third boundary line B3 and the fourth boundary line B4. The insulating sheet 40 is bent such that the first part 43a, the second part 43b, and the third part 43c partially overlap with each other. As a result, both side surfaces S4 of the electrode assembly 20 are covered with the pair of side surface covering portions 43, 43. The side surface S4 of the electrode assembly 20 is covered with the pair of side surface covering portions 43, 43, and the protruding portion is continuous with the pair of end surface covering portions 41, 41 and the pair of side surface covering portions 43, 43 of the insulating sheet 40. The portion 44 is arranged so as to surround the positive electrode tab group 24, the negative electrode tab group 25, the positive electrode conductive member 28, and the negative electrode conductive member 29 of the electrode assembly 20. At this time, two sets of two mountain fold lines Lm are formed in each of the pair of end surface covering portions 41, 41 and the protruding portion 44 continuous with the pair of end surface covering portions 41, 41. Therefore, when the insulating sheet 40 is bent so as to cover the electrode assembly 20, the mountain fold line is formed on each of the pair of end surface covering portions 41, 41 and the protruding portion 44 continuous with the pair of end surface covering portions 41, 41. The mountain fold portion 50 is formed by Lm. Further, the positive electrode facing portion 45a and the negative electrode facing portion 45b of the protruding portion 44 are arranged near the both end surfaces S1 of the electrode assembly 20 in the stacking direction X and apart from the inner surface of the main body member 31 of the case 30. When the electrode assembly 20 is covered with the insulating sheet 40 and the mountain fold portion 50 is formed on the pair of end surface covering portions 41, 41 and the protruding portion 44, the parts 43a, 43b, 43c overlap each other. The fixing tape 81 is attached so as to straddle the place and the second part 43b. This completes the bending of the insulating sheet 40.

Here, the length of the bottom surface covering portion 42 in the short side direction of the insulating sheet 40 will be described.
In the short side direction of the expanded insulating sheet 40, the length of the bottom surface covering portion 42 is set to be slightly longer than the long side of the other end surface S3 of the electrode assembly 20. This is because the mountain fold portion 50 is formed on the pair of end surface covering portions 41, 41 and the protruding portion 44. For example, consider a case where the bottom surface covering portion 42 and the other end surface S3 of the electrode assembly 20 have the same size. In this embodiment, the mountain fold line Lm is formed on the expanded insulating sheet 40. When the mountain fold line Lm is formed on the expanded insulating sheet 40, the insulating sheet 40 is curved with the top T of the mountain fold line Lm as a reference, and the short side of the bottom surface covering portion 42 is formed by the mountain fold line Lm. It is pulled toward the center of 40. Therefore, due to the mountain fold line Lm, the length of the bottom surface covering portion 42 in the short side direction of the insulating sheet 40 becomes shorter than the long side of the other end surface S3 of the electrode assembly 20. When the other end surface S3 of the electrode assembly 20 is mounted on the mounting surface 42a of the bottom cover portion 42 in this state, both side surfaces S4 of the electrode assembly 20 are located outside the short sides of the bottom cover portion 42. When the insulating sheet 40 is bent so as to cover the electrode assembly 20, the insulating sheet 40 is bent outside the short side of the insulating sheet 40 with respect to the third boundary line B3 and the fourth boundary line B4. Can be considered. With this configuration, the position where the mountain fold portion 50 of the insulating sheet 40 is formed may approach the position facing the positive electrode tab group 24 and the negative electrode tab group 25 of the electrode assembly 20 in the stacking direction X. There is. Therefore, in the short-side direction of the insulating sheet 40, the length of the bottom surface covering portion 42 is experimentally confirmed in advance by how much the bottom surface covering portion 42 is shortened due to the bending of the insulating sheet 40 by the mountain fold portion 50. It is set. Further, in the short side direction of the insulating sheet 40, the length of the bottom surface covering portion 42 is such that even if the length of the bottom surface covering portion 42 is shortened due to the bending of the insulating sheet 40 by the top T of the mountain fold portion 50. The mountain fold portion 50 of 40 is set so as not to face the positive electrode tab group 24 and the negative electrode tab group 25 of the electrode assembly 20 in the stacking direction X. In addition, it is conceivable that the length in the short side direction of the insulating sheet 40 may be shortened by forming the mountain fold line Lm on the expanded insulating sheet 40. That is, it is also conceivable that the portion where the first part 43a and the second part 43b of the side surface covering portion 43 partially overlap with each other is reduced. However, even if the length of the insulating sheet 40 in the short side direction and the length of the bottom surface covering portion 42 in the short side direction of the insulating sheet 40 are shortened by the mountain fold line Lm, the size thereof is very small. Therefore, the first part 43a and the second part 43b of the side surface covering portion 43 do not overlap. Therefore, when the electrode assembly 20 is covered with the insulating sheet 40 on which the mountain fold line Lm is formed, the first part 43a and the second part 43b of the side surface covering portion 43 overlap each other. Therefore, a short circuit does not occur between the side surfaces S4 of the electrode assembly 20 and the case 30, and the performance of the power storage device 10 is not affected.

In this embodiment, the following actions and effects can be obtained.
(1-1) In the present embodiment, the tops T of the two mountain folds 50 of the protruding portion 44 are less likely to return to the positive electrode tab group 24 and the negative electrode tab group 25 side of the electrode assembly 20 in the stacking direction X. . Therefore, the tops T of the two mountain folds 50 are easily held at positions separated from both end surfaces S1 of the electrode assembly 20. The two mountain folds 50 of the protruding portion 44 are provided so as to sandwich the positive electrode facing portion 45a and the negative electrode facing portion 45b in the stacking direction X and the direction orthogonal to the protruding direction. That is, the positive electrode facing portion 45a and the negative electrode facing portion 45b of the protruding portion 44 are easily held at positions close to the positive electrode tab group 24 and the negative electrode tab group 25 by forming the two mountain folds 50.

  When welding the lid member 32 and the main body member 31 with the electrode assembly 20 and the insulating sheet 40 accommodated in the main body member 31, the mountain fold portion 50 of the protruding portion 44 of the insulating sheet 40 may melt. However, the positive electrode facing portion 45a and the negative electrode facing portion 45b of the protruding portion 44 are easily held in a state of being separated from the inner surface of the main body member 31 by the mountain fold portion 50 of the protruding portion 44. Therefore, it is possible to improve the insulation between the tab groups 24 and 25 of the electrode assembly 20 and the case.

  (1-2) In this embodiment, the two mountain folds 50 prevent the positive electrode facing portion 45a and the negative electrode facing portion 45b of the protruding portion 44 facing the positive electrode tab group 24 and the negative electrode tab group 25 from melting. it can.

  (1-3) In the present embodiment, the mountain fold portion 50 is formed not only on the protruding portion 44 but also on the pair of end surface covering portions 41, 41 in a state where the electrode assembly 20 is covered with the insulating sheet 40. . Compared with the case where the mountain folds 50 are formed only on the protruding portions 44, the tops T of the mountain folds 50 of the protruding portions 44 are less likely to return due to the tab groups 24 and 25 of the electrode assembly 20 in the stacking direction X. Become. Therefore, the mountain fold portion 50 of the protruding portion 44 is more likely to be held by being protruded toward the inner side surface of the main body member 31 than the positive electrode facing portion 45a and the negative electrode facing portion 45b of the protruding portion 44. Therefore, melting of the positive electrode facing portion 45a and the negative electrode facing portion 45b in the protruding portion 44 of the insulating sheet 40 can be further suppressed.

  (1-4) In this embodiment, the mountain fold line Lm is formed on the base portion 61 of the expanded insulating sheet 40. Therefore, as compared with the case where the mountain fold line Lm is formed only in the protruding portion 44 or the case where the mountain fold line Lm is formed only in the pair of end surface covering portions 41, 41 and the protruding portion 44, the insulating sheet 40 is provided. Can be simply bent.

  (1-5) In the present embodiment, as described in the effect (1), it is possible to suppress melting of the positive electrode facing portion 45a and the negative electrode facing portion 45b. Therefore, the positive electrode facing portion 45a and the negative electrode facing portion 45b are melted, and a short circuit between the body member 31 of the case 30 and the tab groups 24 and 25 of the electrode assembly 20 can be suppressed. As a result, the insulating property between the electrode assembly 20 and the case 30 in the power storage device 10 can be maintained.

  (1-6) In the present embodiment, it is possible to suppress not only the melting of the positive electrode facing portion 45a and the negative electrode facing portion 45b of the insulating sheet 40 but also the shrinkage of the positive electrode facing portion 45a and the negative electrode facing portion 45b of the insulating sheet 40. . Even when the positive electrode facing portion 45a and the negative electrode facing portion 45b of the insulating sheet 40 are contracted by heat during welding of the lid member 32 and the body member 31, each tab group 24, 25 of the body member 31 of the case 30 and the electrode assembly 20. There is a possibility that a short circuit with will occur. Therefore, shrinkage of the positive electrode facing portion 45a and the negative electrode facing portion 45b of the insulating sheet 40 can be suppressed, and the insulation between the electrode assembly 20 and the case 30 in the power storage device 10 can be maintained.

<Second Embodiment>
Hereinafter, a second embodiment of the power storage device will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

  As shown in FIG. 5, in the positive electrode tab group 24 and the negative electrode tab group 25 provided on the one end surface S2 of the electrode assembly 20, all the tabs 24a and 25a are brought closer to one end in the stacking direction X of the electrode assembly 20. It is composed by collecting and stacking. Each of the positive electrode tab group 24 and the negative electrode tab group 25 includes a proximal end side bent portion R1 near one end in the stacking direction X. In the positive electrode tab group 24 and the negative electrode tab group 25, the base end side bent portions R1 are gathered near one end in the stacking direction X and bent from one end in the stacking direction X toward the other end in the stacking direction X. Including parts. In addition, the positive electrode tab group 24 and the negative electrode tab group 25 are provided with an extending portion R2. The extending portion R2 is a portion extending from the base end side bent portion R1 toward the other end of the electrode assembly 20 in the stacking direction X. Each of the positive electrode tab group 24 and the negative electrode tab group 25 includes a front end side bent portion R3 that is bent from the other end in the stacking direction X toward one end in the stacking direction X.

  The power storage device 10 includes a rectangular insulating cover 60 provided in the case 30 between the one end surface S2 of the electrode assembly 20 and the lower surface 32a of the lid member 32. The insulating cover 60 is made of resin. The insulating cover 60 includes a first insulating cover 60a mounted from the positive electrode tab group 24 and the negative electrode tab group 25 toward the tip side bent portion R3, and from the proximal end side bent portion R1 of the positive electrode tab group 24 and the negative electrode tab group 25. It is composed of the attached second insulating cover 60b.

  The first insulating cover 60a has a portion having a U-shaped cross section when cut along the stacking direction X of the electrode assembly 20. Specifically, the first insulating cover 60a includes a rectangular plate-shaped first portion 71, a rectangular plate-shaped second portion 72, one side along the long side direction of the first portion 71, and the length of the second portion 72. It is provided with the 3rd part 73 connected with one side along a side direction. The respective surfaces of the first portion 71 and the second portion 72 extend in the direction along the lower surface 32a of the lid member 32.

  The first portion 71 of the first insulating cover 60a is arranged between the lower surface 32a of the lid member 32 and the conductive members 28, 29. The first portion 71 is supported by the conductive members 28 and 29. The first portion 71 includes a rib 64 protruding toward the electrode assembly 20 from a facing surface facing the one end surface S2 of the electrode assembly 20. The rib 64 includes a locking recess 64 a that is recessed toward the lid member 32. The second portion 72 is provided between the one end surface S2 of the electrode assembly 20 and the tip side bent portion R3 of the positive electrode tab group 24 and the negative electrode tab group 25. The second portion 72 is provided so as to sandwich the tip side bent portion R3 with the first portion 71. Therefore, the tip side bent portion R3 is in a state of entering the space defined by the conductive members 28 and 29, the second portion 72, and the third portion 73. The third portion 73 is provided so as to cover the tip side bent portions R3 of the positive electrode tab group 24 and the negative electrode tab group 25 from the other end of the electrode assembly 20 in the stacking direction X. The third portion 73 is located between the other end of the positive electrode tab group 24 and the negative electrode tab group 25 in the stacking direction X and the inner surface of the main body member 31 in the stacking direction X, and insulates the tip side bent portion R3. There is.

  The second insulating cover 60b includes a rectangular plate-shaped first portion 75. The first portion 75 is arranged between the lower surface 32 a of the lid member 32 and the conductive members 28, 29. The first portion 75 includes a locking protrusion 66 that protrudes toward the first insulating cover 60a. The locking protrusion 66 is provided with a locking claw 66a at its tip. The locking claw 66a can be locked in the locking recess 64a of the first insulating cover 60a.

  The first insulating cover 60a and the second insulating cover 60b are integrally assembled by locking the locking claw 66a of the second insulating cover 60b in the locking recess 64a of the first insulating cover 60a. The cover 60 is a rectangular cover member.

  The protruding portion 44 of the insulating sheet 40 is arranged so as to surround the third portion 73 of the insulating cover 60 in addition to the positive electrode tab group 24, the negative electrode tab group 25, the positive electrode conductive member 28, and the negative electrode conductive member 29. The protruding portion 44 overlaps the third portion 73 of the first insulating cover 60a to improve the insulating property between the electrode assembly 20 and the main body member 31 of the case 30.

  Further, two mountain folds 50 are provided on one of the protruding portions 44 continuous with the pair of end surface covering portions 41, 41 of the insulating sheet 40. One of the protruding portions 44 of the present embodiment indicates the protruding portion 44 provided near one end of the electrode assembly 20 in the stacking direction X. The arrangement of the two mountain fold portions 50 is the same as that of the first embodiment, and thus the description thereof is omitted. The third portion 73 of the first insulating cover 60a is provided between the other of the protruding portions 44 continuous with the pair of end surface covering portions 41, 41 of the insulating sheet 40 and the positive electrode tab group 24 and the negative electrode tab group 25. As a result, the body member 31, the positive electrode tab group 24, and the negative electrode tab group 25 are insulated. The third portion 73 of the first insulating cover 60a is an example of an insulating member.

In this embodiment, the following actions and effects can be obtained.
(2-1) In the present embodiment, the two mountain fold portions 50 provided on one of the protruding portions 44 continuous with the pair of end surface covering portions 41, 41 of the insulating sheet 40 are formed so that the positive electrode faces the positive electrode. One of the portions 45a and one of the negative electrode facing portions 45b are easily held at a position close to the tab groups 24 and 25. Further, a third portion 73 of the first insulating cover 60a is provided between the other of the protruding portions 44 continuous with the pair of end surface covering portions 41, 41 and the tab groups 24, 25. Therefore, even if the other of the positive electrode facing portion 45a and the other of the negative electrode facing portion 45b are melted, the third portion 73 can insulate the case 30 and the tab groups 24 and 25 from each other. Therefore, the insulation between the tab groups 24 and 25 of the electrode assembly 20 and the case 30 can be improved.

  The first and second embodiments can be modified and implemented as follows. The first and second embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

  In the first embodiment, the mountain fold line Lm is also formed on the bottom surface covering portion 42 of the expanded insulating sheet 40, but the invention is not limited to this. For example, the mountain fold line Lm may be formed only on the pair of end surface covering portions 41, 41 and the protruding portion 44 in the base portion 61 of the insulating sheet 40 in the expanded state.

Similarly, also in the second embodiment, the mountain fold portion 50 may be formed only on the other of the pair of end surface covering portions 41, 41 of the expanded insulating sheet 40 and the protruding portion 44.
-In 1st Embodiment, although the mountain fold part 50 was arrange | positioned so that each of each tab group 24 and 25 may be pinched | interposed, it is not restricted to this. For example, you may change as follows.

  As shown in FIG. 6, the plurality of mountain folds 50 may be arranged so as to sandwich the tab group 70 constituted by the positive electrode tab group 24 and the negative electrode tab group 25. Specifically, of the mountain folds 50 in the present embodiment, only two mountain folds 50 provided near the pair of side surface covering portions 43, 43 of the insulating sheet 40 are adopted, and the remaining two mountain folds are used. It is also possible to omit the section 50. Note that the mountain fold portion 50 according to the second embodiment may be similarly changed.

  In the first embodiment and the modified example described above, the two mountain fold portions 50 may be formed only in the protruding portion 44. Even with such a change, the mountain fold portion 50 can suppress melting of the positive electrode facing portion 45a and the negative electrode facing portion 45b of the insulating sheet 40. Therefore, the insulation between the tab groups 24 and 25 of the electrode assembly 20 and the case 30 can be improved.

  Similarly, in the second embodiment and the above-described modified example, the two mountain fold portions 50 may be formed only in the protruding portion 44. Even with such a change, the mountain fold portion 50 can suppress melting of one of the positive electrode facing portion 45a and the negative electrode facing portion 45b of the insulating sheet 40. Therefore, the insulation between the tab groups 24 and 25 of the electrode assembly 20 and the case 30 can be improved.

In the second embodiment, the third portion 73 of the first insulating cover 60a may be provided only in the portion facing the positive electrode tab group 24 and the negative electrode tab group 25.
In the second embodiment, the insulating cover 60 is composed of the first insulating cover 60a and the second insulating cover 60b, but if it is possible to insulate between the lid member 32 and each conductive member 28, 29. You can change it in any way. For example, the insulating cover 60 may be modified so as to be configured by one component instead of the two components of the first insulating cover 60a and the second insulating cover 60b. When the insulating cover 60 is composed of two parts, the same structure as the third portion 73 of the first insulating cover 60a may be added to the second insulating cover 60b.

  Further, consider a case where the second portion 72 and the third portion 73 of the first insulating cover 60a are omitted when changing the structure of the insulating cover 60. In that case, a change is made so that an insulating member is newly provided between each tab group 24, 25 of the electrode assembly 20 and the protruding portion 44. As an example of the insulating member, a plate-like insulating member integrally provided on the lower surface 32a of the lid member 32 may be modified. The lid member 32 is arranged between the tab groups 24 and 25 and the inner surface of the body member 31 when the lid member 32 is arranged so as to close the opening 31 a of the body member 31.

  In the second embodiment, one of the protruding portions 44 is the protruding portion 44 provided near one end of the electrode assembly 20 in the stacking direction X, but, for example, in the stacking direction X of the electrode assembly 20. The protruding portion 44 may be provided near the other end. In this case, as described in the above modified example, a configuration equivalent to the third portion 73 of the first insulating cover 60a is added to the second insulating cover 60b to form an insulating member. Further, the place where the mountain fold portion 50 of the insulating sheet 40 is provided is appropriately changed.

The electrode assembly 20 is not limited to the rectangular column shape, and may be a rectangular column shape. Further, the internal space of the main body member 31 may be appropriately changed according to the shape of the electrode assembly 20.
The part of the pair of side surface covering portions 43, 43 where the first part 43a, the second part 43b, and the third part 43c overlap is fixed by sticking the fixing tape 81. It may be welded using an agent or ultrasonic waves.

  The insulating sheet 40 includes the bottom surface covering portion 42, but the invention is not limited to this. For example, the insulating sheet 40 may be configured by a pair of end face coating portions 41, 41 and a pair of side surface coating portions 43, 43 with the bottom surface coating portion 42 omitted. Even in this case, the mountain fold portion 50 described in the present embodiment and the modified example described above is formed in the protruding portion 44. Then, preferably, another insulator is used so as to cover the other end surface S3 of the electrode assembly 20 as an alternative in which the bottom surface covering portion 42 is omitted, and the other end surface S3 of the electrode assembly 20 and the main body member 31 are It is advisable to insulate the bottom surface.

The power storage device 10 is not limited to the lithium ion secondary battery, and may be another secondary battery such as a nickel hydrogen battery.
The power storage device 10 is not limited to the secondary battery, and may be, for example, a capacitor such as an electric double layer capacitor or a lithium ion capacitor.

  The power storage device 10 has been limited to that used to drive the traveling motor of the vehicle, but is not limited to this, and the use purpose may be changed as appropriate as long as it is used in another unit that uses the stored electricity. it can.

  10 ... Power storage device, 20 ... Electrode assembly, 21 ... Positive electrode, 22 ... Negative electrode, 24 ... Positive electrode tab group, 25 ... Negative electrode tab group, 30 ... Case, 31 ... Main body member, 31a ... Main body member opening, 32 ... Lid Member, 33 ... Welded portion, 40 ... Insulation sheet, 41 ... End surface covering portion, 42 ... Bottom surface covering portion, 42a ... Placement surface, 43 ... Side surface covering portion, 43a ... First part, 43b ... Second part, 43c ... Third part, 44 ... Projection part, 50 ... Mountain fold part, 61 ... Base part, 62 ... Extension part, 70 ... Tab group, X ... Stacking direction, S1 ... Both end faces, S2 ... One end face, S3 ... Other end face , S4 ... Both side surfaces, B1 ... First boundary line, B2 ... Second boundary line, B3 ... Third boundary line, B4 ... Fourth boundary line, Lm ... Mountain fold line, T ... Top part.

Claims (4)

An electrode assembly in which the positive electrode and the negative electrode are stacked, and the tab group extends on one end face in the stacking direction in a direction orthogonal to the stacking direction,
A case having a bottomed cylindrical main body member that accommodates the electrode assembly, a lid member that is provided so as to close the opening of the main body member, and a welded portion in which the main body member and the lid member are welded to each other. When,
A power storage device comprising: an insulating sheet provided between the electrode assembly and the case to insulate the electrode assembly from the case,
The insulating sheet includes a pair of end face coating portions that cover both end faces of the electrode assembly in the stacking direction, and the electrode assembly orthogonal to the both end faces of the electrode assembly and the one end face of the electrode assembly. A pair of side surface covering portions that cover both side surfaces of the electrode assembly, a pair of end surface covering portions and a pair of side surface covering portions, and extend toward the protruding direction of the tab group along the both end surfaces of the electrode assembly. A protruding portion arranged so as to surround the tab group,
In a state where the electrode assembly is covered with the insulating sheet, each of the protruding portions continuous with the pair of end surface covering portions extends along the projecting direction, and is a direction orthogonal to the stacking direction and the projecting direction. In, two mountain folds are formed so as to be located outside the tab group,
The power storage device, wherein the tops of the two mountain folds extending along the protruding direction are arranged at positions separated from the both end surfaces of the electrode assembly in the stacking direction. An electrode assembly in which the positive electrode and the negative electrode are stacked, and the tab group extends on one end face in the stacking direction in a direction orthogonal to the stacking direction,
A case having a bottomed cylindrical main body member that accommodates the electrode assembly, a lid member that is provided so as to close the opening of the main body member, and a welded portion in which the main body member and the lid member are welded to each other. When,
A power storage device comprising: an insulating sheet provided between the electrode assembly and the case to insulate the electrode assembly from the case,
The insulating sheet includes a pair of end face coating portions that cover both end faces of the electrode assembly in the stacking direction, and the electrode assembly orthogonal to the both end faces of the electrode assembly and the one end face of the electrode assembly. A pair of side surface covering portions that cover both side surfaces of the electrode assembly, a pair of end surface covering portions and a pair of side surface covering portions, and extend toward the protruding direction of the tab group along the both end surfaces of the electrode assembly. A protruding portion arranged so as to surround the tab group,
In a state where the electrode assembly is covered with the insulating sheet, one of the protruding portions that is continuous with the pair of end surface covering portions extends along the protruding direction, and is a direction orthogonal to the stacking direction and the protruding direction. In, two mountain folds are formed so as to be located outside the tab group,
An electric storage device is provided between the main body member and the tab group, and an insulating member is provided between the tab group and the other of the protruding portions that are continuous with the pair of end surface covering sections. apparatus. The tab group includes a positive electrode tab group and a negative electrode tab group formed by stacking tabs of the same polarity formed on the positive electrode and the negative electrode,
The two mountain folds are formed so as to be located outside each of the positive electrode tab group and the negative electrode tab group in a direction orthogonal to the stacking direction and the projecting direction. The power storage device according to claim 1 or 2. The insulating sheet has a bottom surface covering portion that covers the other end surface of the electrode assembly opposite to the one end surface,
In a state where the insulating sheet is unfolded, the insulating sheet has a rectangular shape and is sandwiched between the pair of end surface covering portions and the pair of end surface covering portions and forms a first boundary line and a second boundary line. A base part having the bottom surface covering part continuous with the pair of end face covering parts, and a third boundary line and a fourth boundary line that sandwich the base part and are orthogonal to the first boundary line and the second boundary line. An extension having the pair of side surface covering portions that are continuous with the base portion via the base portion, and the protruding portion that is continuous with the base portion and the pair of side surface covering portions and extends toward the outer periphery of the insulating sheet. And a section,
When the insulating sheet is unfolded from the state of covering the electrode assembly, the other end surface of the electrode assembly in the bottom surface covering portion is placed on the base portion and the protruding portion of the insulating sheet. When viewed from the side opposite to the mounting surface, two mountain fold lines parallel to the third boundary line and the fourth boundary line are formed along the tops of the two mountain fold portions. The power storage device according to claim 1 or 3.