JP6044367B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device.

  A secondary battery as a power storage device may include, for example, an electrode assembly in which electrodes are stacked via a separator, and a case in which the electrode assembly is accommodated. For example, Patent Document 1 describes a secondary battery including an insulating sheet that insulates an electrode assembly from a case. Furthermore, for example, Patent Document 2 describes a secondary battery having a pressure release valve that opens the pressure inside the case to the outside of the case when the pressure inside the case exceeds a predetermined opening pressure. In such a secondary battery, when the electrolyte in the case volatilizes due to heat generated by, for example, a short circuit in the electrode assembly, the pressure relief valve opens and the gas is removed from the case. To be discharged.

JP 2003-59537 A JP 2006-216435 A

  Here, if the temperature of the gas discharged outside the case is excessively high, the gas and oxygen in the atmosphere may react. For this reason, it is not preferable that the gas is discharged out of the case at a high temperature.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a power storage device that can suppress discharge of high-temperature gas outside the case.

A power storage device that achieves the above object includes a rectangular parallelepiped electrode assembly in which electrodes are stacked via a separator, a case in which the electrode assembly is accommodated, and an open pressure in which the pressure in the case is predetermined. A pressure release valve that releases the pressure in the case to the outside of the case when exceeding, and an insulating sheet that insulates the electrode assembly from the case, and the electrode assembly includes the pressure release valve The facing surface is an end portion of the electrode, and is exposed to the outer periphery of the electrode assembly in a direction orthogonal to a portion covered with the insulating sheet and a stacking direction of the electrodes. portion and is present, the portion covered with the insulating sheet, the interval seen contains the smallest minimum spacing region between the pressure relief valve and the electrode assembly in the opposed surface, the insulating sheet, the electrode assembly And wherein the covering at least a portion including the minimum interval area of the facing surface, and both laminated surfaces perpendicular to the laminating direction of the electrode in.

  According to such a configuration, since the minimum interval region is covered with the insulating sheet, the gas discharged from the minimum interval region bypasses the insulating sheet and reaches the pressure release valve. Thereby, the length of the gas flow path can be lengthened, and the temperature of the gas can be lowered before reaching the pressure release valve. Therefore, it is possible to suppress discharge of high-temperature gas outside the case.

The insulating sheet is, for covering at least a portion comprising a pair Komen sac Chi minimum spacing region Te electrodes assembly odor, and both laminated surfaces orthogonal to the laminating direction of the electrodes, the electrode assembly It is possible to suppress contact between both the laminated surfaces and the inner surface of the case while bypassing the gas and reaching the pressure release valve.

  In the power storage device, the insulating sheet is wound around the electrode assembly with a direction perpendicular to both the facing direction of the electrode assembly and the pressure release valve and the stacking direction of the electrodes as a winding axis direction, A cylindrical shape opened in a direction orthogonal to both the facing direction and the electrode stacking direction, and both surfaces of the electrode assembly parallel to both the facing direction and the electrode stacking direction are exposed. Good. According to such a configuration, since the insulating sheet is wound around the electrode assembly and has a cylindrical shape opened in a direction orthogonal to both the opposing direction and the electrode stacking direction, the opposing direction in the electrode assembly and the electrode Both surfaces parallel to both sides of the stacking direction are exposed. Thus, with a relatively simple configuration, at least a part of the opposing surface of the electrode assembly including the minimum gap region and both laminated surfaces are covered, and both surfaces parallel to both the opposing direction and the electrode laminating direction are exposed. Can be made. In addition, since both the surfaces of the electrode assembly are exposed, the channel area can be increased as compared with the configuration in which only one of the surfaces is exposed. Thereby, the speed of gas can be reduced and the temperature of gas can be lowered suitably through it.

  In the above power storage device, it is preferable that a part of the insulating sheet overlaps with the stacked surface of the electrode assembly. According to such a configuration, by applying a pressing force to the laminated surface in a state where a part of the insulating sheet is overlapped on the laminated surface, it is possible to suppress the positional deviation of the overlapping portion. Thereby, the position shift of an insulating sheet can be suppressed.

  In the above power storage device, a portion of the insulating sheet that overlaps the stacked surface may be uneven. According to this configuration, due to the unevenness, it is possible to increase the frictional force that acts between overlapping portions of the insulating sheet or between the insulating sheet and the electrode assembly or the case. Thereby, the position shift of an insulating sheet can be suppressed more suitably.

  In the above power storage device, the electrode has a tab at the end, and the tab is located on the facing surface of the electrode assembly and is disposed between the electrode assembly and the case. A conductive member joined to both the tab and the terminal penetrating the case, and the insulating sheet covers the electrode assembly together with the conductive member and the tab. The length of the portion of the insulating sheet covering the conductive member and the tab in the direction perpendicular to both the facing direction and the electrode stacking direction is the stacking surface of the electrode assembly. Shorter than the length in the direction orthogonal to both the facing direction and the electrode stacking direction, and a part of the conductive member protrudes from the open end of the insulating sheet, and protrudes from the insulating sheet. It may be bonded to the terminal at that portion. According to such a configuration, since the insulating sheet is wound together with the conductive member and the tab, the contact between the conductive member and the tab and the inner surface of the case can be suppressed. Further, a part of the conductive member protrudes from the opening end of the insulating sheet, and is joined to the terminal at the protruding portion. Accordingly, the insulating sheet can be wound around the electrode assembly together with the tab and the conductive member without hindering the bonding between the terminal and the conductive member.

  In the above power storage device, it is preferable that the surface of the electrode assembly other than the surface opposite to the facing surface is covered with the insulating sheet, and the surface opposite to the facing surface is exposed. . According to such a configuration, the gas generated in the electrode assembly is discharged from the surface on the side opposite to the pressure release valve, and reaches the pressure release valve. Therefore, the gas flow path can be lengthened, and the temperature of the gas discharged from the pressure release valve can be lowered through it.

  The power storage device may be a secondary battery.

  According to the present invention, high temperature gas can be prevented from being discharged out of the case.

The perspective view of a secondary battery. The exploded perspective view of an electrode assembly. The exploded perspective view of a secondary battery. The perspective view which shows the electrode assembly and lid | cover with which the insulating sheet was wound. The front view which shows the expansion | deployment shape of an insulating sheet. (A) is the 6-6 sectional view taken on the line of FIG. 1, (b) is the elements on larger scale of (a). FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. The disassembled perspective view of the secondary battery of 2nd Embodiment. The front view which shows the expansion | deployment shape of an insulating sheet. The perspective view which shows the bending aspect of an insulating sheet. Sectional drawing which shows the cross-section of a secondary battery. The perspective view which shows the insulating sheet of another example. The front view which shows the expansion | deployment shape of the insulating sheet of another example. (A), (b) is a perspective view which shows the bending aspect of the insulating sheet of another example.

(First embodiment)
Hereinafter, a first embodiment of the power storage device will be described. For the convenience of illustration, FIG. 6 shows the sectional structure of the electrode assembly 14 omitted, and FIG. 7 shows a partial configuration of the electrode assembly 14 and the like in a front view. Furthermore, in FIG.6 and FIG.7, the minimum space | interval area | region P is shown with a dot hatch.

  As shown in FIG. 1, a secondary battery 10 as a power storage device includes a rectangular parallelepiped case 11. The case 11 includes a bottomed box-shaped case main body 12 that opens upward, and a rectangular flat plate-shaped lid 13 that closes the opening of the case main body 12. The case 11 is made of metal, for example, and has a predetermined heat capacity.

  As shown in FIG. 1, the secondary battery 10 includes an electrode assembly 14 and an electrolyte solution 15 accommodated in a case 11, and a positive electrode terminal 16 and a negative electrode terminal used for exchanging power with the electrode assembly 14. 17. Each terminal 16, 17 is on the lid 13 of the case 11 and is arranged in a state of penetrating the lid 13. In addition, the secondary battery 10 of this embodiment is a lithium ion battery, for example.

  Further, the secondary battery 10 includes a pressure release valve 18 that releases the pressure in the case 11 to the outside of the case 11 when the pressure in the case 11 exceeds a predetermined open pressure. The pressure relief valve 18 is in the center of the lid 13 and is located between the terminals 16 and 17. The pressure release valve 18 has a thin film shape that is thinner than the plate thickness of the lid 13. The pressure release valve 18 is cleaved when the pressure in the case 11 exceeds the release pressure. Note that the case where the pressure in the case 11 becomes high means that, for example, the electrolyte solution 15 is volatilized due to heat generation of the electrode assembly 14 and gas is generated in the electrode assembly 14.

  As shown in FIG. 2, the electrode assembly 14 has a structure in which positive electrodes 21 and negative electrodes 22 are alternately stacked via separators 23, which are porous membranes through which ions related to electric conduction can pass. Yes. Each of the electrodes 21 and 22 and the separator 23 is a rectangular sheet.

  The positive electrode 21 includes a rectangular positive metal foil (for example, an aluminum foil) 21a and positive electrode active material layers 21b on both surfaces of the positive metal foil 21a. The negative electrode 22 includes a rectangular negative metal foil (for example, copper foil) 22a and negative electrode active material layers 22b on both surfaces of the negative metal foil 22a. In the state constituting the electrode assembly 14, the positive electrode active material layer 21 b is covered with the negative electrode active material layer 22 b, and the electrodes 21 and 22 are covered with the separator 23.

  As shown in FIG. 2, a positive electrode tab 31 protrudes from the end 21 c of the positive electrode 21. Similarly, a negative electrode tab 32 protrudes from the end 22 c of the negative electrode 22. The electrodes 21 and 22 are stacked so that the same polarities of the tabs 31 and 32 are arranged in a row. As shown in FIG. 3, the negative electrode tabs 32 are gathered together in one of the stacking directions Y of the electrodes 21, 22 and folded back to the other in the gathered state. Similarly, each positive electrode tab 31 is folded back to the other side in a state where the positive electrode tabs 31 are gathered toward one side in the stacking direction Y of the electrodes 21 and 22.

  As shown in FIG. 3, the electrode assembly 14 has a rectangular parallelepiped shape, and is accommodated in the case 11 with the upper surface 14 a having the tabs 31 and 32 facing the pressure release valve 18. Here, on the outer periphery of the electrode assembly 14, the surfaces orthogonal to the stacking direction Y of the electrodes 21 and 22 are the stacked surfaces 14 b and 14 c, and the surface opposite to the upper surface 14 a is the lower surface 14 d. Furthermore, on the outer periphery of the electrode assembly 14, surfaces parallel to both the facing direction Z between the upper surface 14 a and the pressure release valve 18 and the stacking direction Y of the electrodes 21 and 22 are referred to as side surfaces 14 e and 14 f. A direction perpendicular to both the facing direction Z and the stacking direction Y of the electrodes 21 and 22 is defined as a width direction X of the electrode assembly 14. In the present embodiment, the upper surface 14a corresponds to the facing surface. The upper surface 14a has a rectangular shape in which the width direction X of the electrode assembly 14 is the longitudinal direction and the stacking direction Y of the electrodes 21 and 22 is the short direction.

  As shown in FIG. 2, the upper surface 14a is the ends 21c and 22c of the electrodes 21 and 22, and the lower surface 14d is the end of the electrodes 21 and 22 opposite to the ends 21c and 22c where the tabs 31 and 32 are located. 21d and 22d. One side surface 14e is one end portion 21e, 22e adjacent to the end portions 21c, 22c in the electrodes 21, 22, and the other side surface 14f is adjacent to the end portions 21c, 22c in the electrodes 21, 22c. The other ends 21f and 22f.

  Incidentally, as shown in FIG. 3, a minimum interval region P in which the interval between the pressure release valve 18 and the electrode assembly 14 is the smallest in the outer periphery of the electrode assembly 14 is included in the upper surface 14a. The minimum interval region P is a region below the pressure release valve 18 in the upper surface 14a.

  As shown in FIG. 3, the secondary battery 10 includes a positive electrode conductive member 41 and a negative electrode conductive member 42 that electrically connect the same polarities of the tabs 31 and 32 and the terminals 16 and 17. Each of the conductive members 41 and 42 has a plate shape and is disposed between the lid 13 of the case 11 and the electrode assembly 14. The positive electrode conductive member 41 is bonded to both the positive electrode tab 31 and the positive electrode terminal 16. Similarly, the negative electrode conductive member 42 is bonded to both the negative electrode tab 32 and the negative electrode terminal 17. As a joining mode, for example, welding is conceivable.

  As shown in FIG. 4, the secondary battery 10 includes an insulating sheet 50 that insulates the electrode assembly 14 from the case 11. The insulating sheet 50 is a bendable resin sheet, for example. The insulating sheet 50 includes one laminated surface covering portion 51 covering one laminated surface 14b, the other laminated surface covering portion 52 covering the other laminated surface 14c opposite to the one laminated surface 14b, and the electrode assembly 14. The lower surface covering portion 53 is provided to cover the lower surface 14d. One laminated surface covering portion 51 has a first part 51a and a second part 51b, and each part 51a, 51b is overlapped on one laminated surface 14b.

  Further, the insulating sheet 50 includes an upper surface covering portion 54 that covers a part of the upper surface 14 a of the electrode assembly 14. The upper surface covering portion 54 covers a part including the minimum interval region P on the upper surface 14a. At this time, the upper surface covering portion 54 covers the tabs 31 and 32 and the conductive members 41 and 42 together. In the present embodiment, “covering” is not limited to a mode in which an object to be covered such as the upper surface 14a is in contact with an object to be covered such as the upper surface covering portion 54, but may be a mode in which the object is separated by a certain distance. Including.

  As shown in FIG. 4, the insulating sheet 50 is open in the width direction X of the electrode assembly 14, and both side surfaces 14 e and 14 f of the electrode assembly 14 are exposed. Specifically, one side surface 14 e of the electrode assembly 14 is exposed through one opening 61, and the other side surface 14 f of the electrode assembly 14 is exposed through the other opening 62. Yes.

  As shown in FIG. 5, the insulating sheet 50 has a substantially rectangular shape as a whole except that the recessed portion 71 is partly provided in the developed state. The first part 51 a of the one laminated surface covering portion 51, the upper surface covering portion 54, the other laminated surface covering portion 52, the lower surface covering portion 53, and the second part 51 b of the one laminated surface covering portion 51 are the length of the insulating sheet 50. They are lined up in the direction, and adjacent ones are continuous. The insulating sheet 50 is formed by bending the electrode assembly 14 at the boundary line between the covering portions 51 to 54 with the width direction X of the electrode assembly 14 as the winding axis direction in a state where the first part 51a is placed on one laminated surface 14b. By winding around the solid body 14, the electrode assembly 14 has a cylindrical shape opened in the width direction X. At this time, the second part 51 b that is the winding end portion and continues to the lower surface covering portion 53 overlaps the first part 51 a that is the winding start portion and continues to the upper surface covering portion 54.

  Here, as shown in FIG. 6A, in a state where the electrode assembly 14 covered with the insulating sheet 50 is accommodated in the case 11, the insulating sheet 50 has the laminated surface 14 b of the electrode assembly 14, 14 c and the inner surface 11 a of the case 11, and a pressing force is applied to the stacked surfaces 14 b and 14 c of the electrode assembly 14 from the stacking direction Y of the electrodes 21 and 22.

  As shown in FIG.6 (b), the part which overlaps in one laminated surface 14b among the insulating sheets 50 has an unevenness | corrugation. Specifically, the surface of the first part 51a that is in contact with the second part 51b has a recess 81, and the surface of the second part 51b that is in contact with the first part 51a can be fitted into the recess 81. There is a convex portion 82. The first part 51a and the second part 51b overlap with each other in a state where the convex part 82 and the concave part 81 are fitted.

  As shown in FIG. 7, there is a gap 91 between the side surfaces 14 e and 14 f of the electrode assembly 14 and the inner surface 11 a of the case 11. In addition, since the upper surface covering portion 54 covers the upper surface 14a together with the tabs 31 and 32 and the conductive members 41 and 42, there is a gap 92 between the upper surface covering portion 54 and the upper surface 14a. Each of these gaps 91 and 92 constitutes a gas flow path.

  In particular, in this embodiment, there are two openings 61 and 62, and both side surfaces 14e and 14f of the electrode assembly 14 are exposed. The gap 91 is formed between the one side surface 14e and the inner surface 11a of the case 11 and the other side so that the gas discharged from the two openings 61 and 62 can go to the pressure release valve 18, respectively. It exists both between the side surface 14 f and the inner surface 11 a of the case 11.

  The upper surface covering portion 54 is at least on the shortest path between the upper surface 14a and the pressure release valve 18 so as to restrict the gas discharged from the upper surface 14a to reach the pressure release valve 18 through a flow path longer than the shortest flow path. is there. As shown by the one-dot chain line in FIG. 7, a straight line connecting the end of the pressure release valve 18 on the positive electrode terminal 16 side and the boundary between the one side surface 14e and the upper surface 14a of the electrode assembly 14 is a first straight line VL1, pressure A straight line connecting the end of the open valve 18 on the negative electrode terminal 17 side and the boundary between the other side surface 14f and the upper surface 14a of the electrode assembly 14 is defined as a second straight line VL2. In this case, the upper surface covering portion 54 extends over at least a region between the straight lines VL1 and VL2.

  Here, the length X 1 in the width direction X of the electrode assembly 14 of the other laminated surface covering portion 52 is longer than the width X 2 of the electrode assembly 14. The length in the width direction X of the electrode assembly 14 of the one laminated surface covering portion 51 is the same as the length X1 of the electrode assembly 14 in the width direction X of the other laminated surface covering portion 52.

  Further, as shown in FIG. 7, the length X3 in the width direction X of the electrode assembly 14 in the upper surface covering portion 54 is longer than the length X1 in the width direction X of the electrode assembly 14 in the other laminated surface covering portion 52. The distance is shorter than the distance between the terminals 16 and 17 in the width direction X of the electrode assembly 14. For this reason, one opening end 61a of the insulating sheet 50 that divides one opening 61 has a stepped shape in which an upper part with respect to the upper surface 14a is recessed with respect to a lower part with respect to the upper surface 14a. Similarly, the other opening end 62a of the insulating sheet 50 that divides the other opening 62 has a stepped shape with the upper surface 14a as a boundary. A part of the positive electrode conductive member 41 protrudes from one opening end 61 a of the insulating sheet 50, and a part of the negative electrode conductive member 42 protrudes from the other opening end 62 a of the insulating sheet 50. The terminals 16 and 17 are joined at portions of the conductive members 41 and 42 that protrude from the opening ends 61a and 62a of the insulating sheet 50.

  Note that the length X3 of the upper surface covering portion 54 in the width direction X of the electrode assembly 14 is shorter than the width X2 of the electrode assembly 14, and a part of the upper surface 14a on both end sides in the width direction X of the upper surface 14a. Is exposed without being covered with the insulating sheet 50.

Next, the operation of the present embodiment will be described with reference to FIG.
If the pressure release valve 18 is opened due to generation of gas in the case 11, the gas is discharged out of the case 11 through the pressure release valve 18. In this case, it is assumed that the gas is discharged from the upper surface 14a and the side surfaces 14e and 14f. Here, as shown by a two-dot chain line in FIG. 7, the gas discharged from the upper surface 14 a is regulated by the upper surface covering portion 54 so as to go to the pressure release valve 18 in a channel longer than the shortest channel. For this reason, the gas discharged from the upper surface 14 a passes through the gap 92 along the upper surface covering portion 54 and then travels toward the pressure release valve 18.

According to the embodiment described in detail above, the following excellent effects are obtained.
(1) On the outer periphery of the electrode assembly 14, there are both laminated surfaces 14 b and 14 c, a lower surface 14 d, and a part of the upper surface 14 a as a portion covered by the insulating sheet 50, but without being covered by the insulating sheet 50. Both side surfaces 14e and 14f exist as portions exposed in the stacking direction Y of the electrodes 21 and 22. The portion covered with the insulating sheet 50 includes the minimum interval region P where the interval between the pressure release valve 18 and the electrode assembly 14 on the upper surface 14a is the smallest. Thereby, the gas discharged from the minimum interval region P bypasses and reaches the pressure release valve 18. Therefore, the length of the gas flow path can be increased, and the amount of heat of the gas absorbed by the case 11 or the like can be increased by that amount until the gas reaches the pressure release valve 18. Therefore, the temperature of the gas discharged from the pressure release valve 18 can be lowered, and high temperature gas can be prevented from being discharged out of the case 11.

  In particular, the gas generated in the electrode assembly 14 is more easily discharged from the direction perpendicular to the stacking direction Y than the stacking direction Y of the electrodes 21 and 22. In this respect, in the present embodiment, since the portion where gas is relatively easily discharged is exposed without being covered with the insulating sheet 50, the gas can be suitably discharged.

  (2) The insulating sheet 50 covers both the stacked surfaces 14b and 14c orthogonal to the stacking direction Y of the electrodes 21 and 22 in the electrode assembly 14. Thereby, the contact between both the laminated surfaces 14b and 14c and the inner surface 11a of the case 11 can be avoided in a state where the gas in the electrode assembly 14 can be discharged.

  Further, in a state where the electrode assembly 14 covered with the insulating sheet 50 is accommodated in the case 11, the insulating sheet 50 is sandwiched between the laminated surfaces 14 b and 14 c and the inner surface 11 a of the case 11. Thereby, a pressing force is applied to the electrode assembly 14 from the stacking direction Y of the electrodes 21 and 22. Therefore, it is possible to apply an appropriate pressing force to the electrode assembly 14 while avoiding contact between the electrode assembly 14 and the inner surface 11a of the case 11, and the displacement of the electrode assembly 14 in the case 11 can be prevented. Can be suppressed. Therefore, there is an inconvenience that there is an exposed portion used for gas discharge on the outer periphery of the electrode assembly 14, that is, the electrode assembly 14 is displaced while the side surfaces 14e and 14f of the electrode assembly 14 are exposed. It can suppress that side surface 14e, 14f of the assembly 14 and the inner surface 11a of the case 11 contact.

  (3) The insulating sheet 50 has the width direction X of the electrode assembly 14 orthogonal to both the facing direction Z of the electrode assembly 14 and the pressure release valve 18 and the stacking direction Y of the electrodes 21 and 22 as the winding axis direction. The cylindrical shape is wound around the electrode assembly 14 and opened in the width direction X of the electrode assembly 14. As a result, both side surfaces 14 e and 14 f of the electrode assembly 14 are exposed through the openings 61 and 62 opened in the width direction X of the electrode assembly 14. Therefore, with a relatively simple configuration, it is possible to cover a part of the upper surface 14a including the minimum gap region P and both the laminated surfaces 14b and 14c, and to expose the both side surfaces 14e and 14f of the electrode assembly 14. Furthermore, since both side surfaces 14e and 14f of the electrode assembly 14 are exposed, the gas flow passage area is larger than the configuration in which only one side surface 14e is exposed. Thereby, the speed of gas can be reduced and the temperature of gas can be lowered suitably.

  (4) A part of the insulating sheet 50 is overlapped on the one laminated surface 14b. Specifically, the first part 51a of the one laminated surface covering portion 51 corresponding to the winding start portion and the second part 51b of the one laminated surface covering portion 51 corresponding to the winding end portion are arranged on the one laminated surface 14b. Are overlapping. Accordingly, the first part 51a and the second part 51b are sandwiched between the electrode assembly 14 and the inner surface 11a of the case 11 in an overlapping state. Therefore, the position shift of both can be suppressed and the position shift of the insulating sheet 50 can be suppressed through it.

  (5) The second part 51 b continuing to the lower surface covering portion 53 overlaps the first part 51 a continuing to the upper surface covering portion 54. Thereby, one lamination surface coating | coated part 51 and the lower surface coating | coated part 53 continue. Therefore, when the electrode assembly 14 around which the insulating sheet 50 is wound is inserted into the case 11 with the lower surface 14d side as an insertion destination, the insulating sheet 50 is not easily caught. Accordingly, it is possible to suppress the displacement of the insulating sheet 50 that may occur when the electrode assembly 14 around which the insulating sheet 50 is wound is inserted into the case 11.

  (6) The surface of the insulating sheet 50 that is overlapped with one of the laminated surfaces 14b is uneven. Thereby, the position shift of the 1st part 51a and the 2nd part 51b can be suppressed more suitably.

  (7) The insulating sheet 50 is wound around the electrode assembly 14 so as to cover the electrode assembly 14 together with the tabs 31 and 32 on the upper surface 14 a and the conductive members 41 and 42 joined to the tabs 31 and 32. ing. Thereby, contact with tab 31 and 32 and conductive members 41 and 42 and inner surface 11a of case 11 can also be controlled.

  Further, the length X3 of the electrode assembly 14 in the width direction X of the upper surface covering portion 54 covering the tabs 31 and 32 and the conductive members 41 and 42 is the other laminated surface covering portion covering the other laminated surface 14c. 52 of the electrode assemblies 14 is shorter than the length X1 in the width direction X. A part of the conductive members 41 and 42 protrudes from the open ends 61a and 62a of the insulating sheet 50, and is joined to the terminals 16 and 17 at the protruding portions. Therefore, the insulating sheet 50 can be wound around the electrode assembly 14 without hindering the bonding between the terminals 16 and 17 and the conductive members 41 and 42.

  In addition, for the purpose of shortening the length X3 of the upper surface covering portion 54, a part of both ends in the longitudinal direction of the upper surface 14a is exposed, but a part of both ends in the longitudinal direction is in the short direction. Compared to the both end sides, the distance to the pressure release valve 18 is relatively long. For this reason, the temperature of the gas discharged from the pressure release valve 18 is unlikely to be high even when a part of both ends in the longitudinal direction of the upper surface 14a is exposed.

(Second Embodiment)
In the present embodiment, the position of the pressure release valve and the shape of the insulating sheet are different from those in the first embodiment. The different points will be described below. In addition, about the structure similar to 1st Embodiment, while attaching | subjecting the same code | symbol, the detailed description is abbreviate | omitted.

  As shown in FIG. 8, in this embodiment, the pressure release valve 18 is at the center of the bottom 12 a of the case body 12. Moreover, the insulating sheet 100 of this embodiment is a bottomed box shape opened upward. The insulating sheet 100 includes laminated surface covering portions 101 and 102 that cover the laminated surfaces 14b and 14c of the electrode assembly 14, a lower surface covering portion 103 that covers the lower surface 14d of the electrode assembly 14, and side surfaces 14e and 14f of the electrode assembly 14. And side surface covering portions 104 and 105 covering the same.

  One laminated surface covering portion 101 includes a first part 101 a that is continuous with one of the side surface covering portions 104 and 105, and a second part 101 b that is continuous with the lower surface covering portion 103. The first part 101a and the second part 101b overlap each other on the one laminated surface 14b. At this time, the second part 101b is disposed on the first part 101a, and the one laminated surface covering portion 101 and the lower surface covering portion 103 are continuous. Similarly, the other laminated surface covering portion 102 includes a first part 102 a that is continuous with one of the side surface covering portions 104 and 105, and a second part 102 b that is continuous with the lower surface covering portion 103.

  As shown in FIG. 9, the insulating sheet 100 of the present embodiment is a single rectangular shape in the unfolded state. In a state where the insulating sheet 100 is unfolded, the side surface covering portions 104 and 105 are provided on both sides in the longitudinal direction of the insulating sheet 100 with respect to the lower surface covering portion 103. The first parts 101a and 102a are provided on both sides in the short direction of the insulating sheet 100 with respect to one side surface covering portion 104, and similarly both sides in the short direction of the insulating sheet 100 with respect to the other side surface covering portion 105. There are first parts 101a and 102a. Furthermore, there are second parts 101 b and 102 b on both sides of the insulating sheet 100 in the short direction with respect to the lower surface covering portion 103. The first part 101a and the second part 101b of one laminated surface covering part 101 are arranged in the longitudinal direction of the insulating sheet 100, and the first part 102a and the second part 102b of the other laminated surface covering part 102 are insulated. The sheets 100 are arranged in the longitudinal direction. There is a notch 112 at the boundary between the parts 101 a and 101 b of the one laminated surface covering portion 101 and the boundary between the parts 102 a and 102 b of the other laminated surface covering portion 102. The insulating sheet 100 is bent along the outer shape of the electrode assembly 14 and has a bottomed box shape that covers the five surfaces excluding the upper surface 14 a of the electrode assembly 14.

  The bending mode will be described in detail. As shown in FIG. 10, the insulating sheet 100 has a side surface of the electrode assembly 14 in a state where the lower surface 14 d of the electrode assembly 14 is placed on the lower surface covering portion 103. 14e and 14f are bent so as to be covered with the side surface covering portions 104 and 105. Then, the insulating sheet 100 is bent so that the laminated surfaces 14b and 14c are covered with the first parts 101a and 102a, and the second parts 101b and 102b are overlapped with the first parts 101a and 102a. Is bent.

  As in the first embodiment, in a state where the electrode assembly 14 is accommodated in the case 11, the insulating sheet 100 is sandwiched between the laminated surfaces 14 b and 14 c of the electrode assembly 14 and the inner surface 11 a of the case 11. A pressing force is applied to the electrode assembly 14 from the stacking direction Y of the electrodes 21 and 22.

  As shown in FIG. 11, because the pressure release valve 18 is on the bottom 12 a of the case body 12, the lower surface 14 d of the electrode assembly 14 faces the pressure release valve 18, and the electrode assembly 14 and the pressure release valve 18 are The minimum interval region P having the smallest interval is included in the lower surface 14 d of the electrode assembly 14. The entire lower surface 14 d of the electrode assembly 14 is covered with the lower surface covering portion 103. On the other hand, the upper surface 14 a of the electrode assembly 14 opposite to the lower surface 14 d on the pressure release valve 18 side is exposed through the opening 111 of the insulating sheet 100. In the present embodiment, the lower surface 14d corresponds to the facing surface.

  As shown in FIG. 11, there is a gap 113 through which gas can pass between the lower surface covering portion 103 and the bottom portion 12 a of the case body 12. The gap 113 and the gap 91 constitute a gas flow path.

Next, the effect | action of this embodiment is demonstrated using FIG.
When the pressure release valve 18 is opened by the gas generated in the case 11, the gas in the electrode assembly 14 is released through the gap 91 and the gap 113 as shown by a two-dot chain line in FIG. 11. The valve 18 is reached.

According to this embodiment, in addition to the effects (2), (4), and (5), the following excellent effects are achieved.
(8) In the configuration in which the pressure release valve 18 is at the bottom 12a of the case body 12, the lower surface 14d facing the pressure release valve 18 in the electrode assembly 14 is covered with the insulating sheet 100, but is opposite to the lower surface 14d. The upper surface 14a is exposed. Thereby, the gas generated in the electrode assembly 14 is discharged from the upper surface 14 a farthest from the pressure release valve 18, bypasses and reaches the pressure release valve 18. Therefore, the length of the gas flow path can be increased, and the temperature of the gas discharged from the pressure release valve 18 can be lowered.

  (9) Both side surfaces 14 e and 14 f of the electrode assembly 14 are covered with the insulating sheet 100. Thereby, contact with both the side surfaces 14e and 14f of the electrode assembly 14 and the inner surface 11a of the case 11 can be avoided.

In addition, you may change each said embodiment as follows.
In the first embodiment, the side surfaces 14e and 14f of the electrode assembly 14 are exposed, but the present invention is not limited to this. For example, as shown in FIG. 12, an insulating sheet 120 having a side surface covering portion 121 that covers one side surface 14e may be used. In short, it is sufficient that at least one of the both side surfaces 14e and 14f of the electrode assembly 14 is exposed. In this case, the insulating sheet 120 may be continuous with the side surface covering portion 121, and may include the third part 51 c included in the one laminated surface covering portion 51. And each part 51a-51c is good to overlap in one lamination surface 14b. Thereby, the position shift of the side surface covering part 121 can be suppressed. As shown in FIG. 13, in the insulation sheet 120 of this another example, the side surface covering portion 121 and the third part 51 c are continuously provided on the side of the other laminated surface covering portion 52 in the unfolded state. is there. Then, as shown in FIGS. 14A and 14B, after the insulating sheet 120 is wound around the lower surface covering portion 53 in a state where the first part 51a is placed on the one laminated surface 14b, The side surface covering part 121 and the third part 51c are wound around the second part 51b.

  In the first embodiment, the first part 51a and the second part 51b may be configured to partially overlap each other or may be configured to entirely overlap. In short, it is sufficient that at least a part of both overlap. Note that, from the viewpoint of suppressing the displacement of the insulating sheet 50, it is preferable that the overlapping areas are large.

  In the first embodiment, one laminated surface covering portion 51 has a configuration including the first part 51a and the second part 51b that overlap each other, but is not limited thereto. For example, one of the first part 51a and the second part 51b may be omitted, and a part of the insulating sheet 50 may be configured not to overlap the stacked surfaces 14b and 14c of the electrode assembly 14.

  The pressure release valve 18 may be disposed at a position facing either one of the side surfaces 14 e and 14 f of the electrode assembly 14 in the case 11. In this case, the insulating sheet may be wound around with the vertical direction as the winding axis direction so that the upper surface 14a and the lower surface 14d of the electrode assembly 14 are exposed.

  In the first embodiment, the length X3 in the width direction X of the electrode assembly 14 of the upper surface covering portion 54 is shorter than the length X1 in the width direction X of the electrode assembly 14 of the other laminated surface covering portion 52. However, the present invention is not limited to this, and the length X3 of the upper surface covering portion 54 may be the same as the length X1 of the other laminated surface covering portion 52. In this case, it is preferable that the upper surface covering portion 54 has a slit through which the terminals 16 and 17 can be inserted.

  In the first embodiment, the overlapping portions have irregularities, but instead of this, a configuration having a non-slip slit or the like may be used. In addition, only one of the surfaces in contact with each other in the first part 51a and the second part 51b may be uneven, and the other surface may be flat, or both of the surfaces in contact with each other may be flat. It may be.

  ○ The surface of the first part 51a and the second part 51b opposite to the surfaces that contact each other, specifically, the surface that contacts one laminated surface 14b of the first part 51a, and the case 11 of the second part 51b Both the inner surface 11a and the surface in contact with the inner surface 11a may be uneven. In this case, since the frictional force that acts between the insulating sheet 50 and the electrode assembly 14 and the case 11 is increased, the displacement of the insulating sheet 50 with respect to the electrode assembly 14 and the case 11 can be suppressed. Further, the unevenness may be provided only on one of the contact surface with the one laminated surface 14b of the first part 51a and the contact surface with the inner surface 11a of the case 11 in the second part 51b. Further, in addition to both of the first part 51a and the second part 51b that are in contact with each other, the first part 51a is in contact with the one laminated surface 14b and the second part 51b is in contact with the inner surface 11a of the case 11. Both contact surfaces may be uneven.

  ○ A portion covered with an insulating sheet and a portion exposed in a direction perpendicular to the electrode stacking direction exist on the outer periphery of the electrode assembly 14, and the portion covered with the insulating sheet includes the minimum gap region P. If so, the specific shapes of the insulating sheet and the electrode assembly are arbitrary.

  O The magnitude relationship of the external shape of the positive electrode 21, the negative electrode 22, and the separator 23 is arbitrary. The positive electrode 21, the negative electrode 22, and the separator 23 may have the same shape, or the positive electrode 21 may be smaller than the negative electrode 22 and the negative electrode 22 may be smaller than the separator 23 in a front view.

  As long as the upper surface 14a, both side surfaces 14e and 14f, and the lower surface 14d of the electrode assembly 14 are constituted by the positive electrode 21, the negative electrode 22, and the end surface of the separator 23, they may be flush or uneven. It may be a shape. For example, when the positive electrode 21, the negative electrode 22, and the separator 23 have the same shape, the upper surface 14a, the side surfaces 14e, 14f, and the lower surface 14d are flush with each other. On the other hand, when the positive electrode 21, the negative electrode 22, and the separator 23 are not the same shape, at least one of the upper surface 14a, the side surfaces 14e, 14f, and the lower surface 14d has an uneven shape.

  The pressure release valve 18 is not limited to being opened when the release pressure is exceeded, but may be when the release pressure is equal to or higher than the release pressure. Alternatively, the fact that it can be cleaved when the pressure is lower than the designed opening pressure does not differ from the pressure releasing valve 18 of the present case.

  The electrode assembly may have a structure in which, for example, a strip-shaped electrode and a separator are wound. In this case, the electrode assembly and the pressure release valve are arranged so that the surface that is orthogonal to the winding axis direction and the end in the longitudinal direction of the electrode in the electrode assembly is an opposing surface that faces the pressure release valve. And the minimum space | interval area | region in an opposing surface is covered with the insulating sheet, and at least one part of the surface on the opposite side to the area | region other than the minimum spacing area | region among the opposing surfaces and the said opposing surface is good.

O The material of the insulating sheet is arbitrary, and may have heat resistance such as polyphenylene sulfide.
The secondary battery 10 may be mounted on a vehicle and used for traveling, or may be used as a stationary power source.

  The secondary battery 10 is a lithium ion battery, but is not limited thereto, and may be another secondary battery. In short, any ion may be used as long as ions move between the positive electrode active material layer 21b and the negative electrode active material layer 22b and transfer charges. Further, an electric double layer capacitor may be used as the power storage device.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(A) In the electrode assembly, at least one of both surfaces parallel to both the opposing direction of the pressure release valve and the electrode assembly and the electrode stacking direction may be exposed.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 11 ... Case, 14 ... Electrode assembly, 14a-14f ... Each surface of an electrode assembly, 16, 17 ... Terminal, 18 ... Pressure release valve, 21, 22 ... Electrode, 23 ... Separator, 31 , 32 ... tab, 41, 42 ... conductive member, 50 ... insulating sheet, 61, 62 ... opening, 100 ... insulating sheet of the second embodiment, 120 ... insulating sheet of another example.

Claims (7)

A rectangular parallelepiped electrode assembly in which electrodes are stacked via a separator;
A case in which the electrode assembly is accommodated;
A pressure release valve for releasing the pressure in the case to the outside of the case when the pressure in the case exceeds a predetermined opening pressure;
An insulating sheet that insulates the electrode assembly from the case;
With
The electrode assembly has a facing surface facing the pressure relief valve, the facing surface being an end of the electrode;
On the outer periphery of the electrode assembly, there are a portion covered by the insulating sheet and a portion exposed in a direction orthogonal to the stacking direction of the electrodes, and the portion covered by the insulating sheet is the facing surface distance between the electrode assembly and the pressure relief valve is seen contains the smallest minimum spacing region in,
The power storage device , wherein the insulating sheet covers at least a part of the electrode assembly including the minimum spacing region of the facing surface and both stacked surfaces orthogonal to the stacking direction of the electrodes . The insulating sheet is wound around the electrode assembly with a direction orthogonal to both the facing direction of the electrode assembly and the pressure release valve and the stacking direction of the electrodes as a winding axis direction. It is a cylindrical shape that opens in a direction orthogonal to both of the electrode stacking directions,
The power storage device according to claim 1, wherein both surfaces of the electrode assembly parallel to both the facing direction and the electrode stacking direction are exposed.   The power storage device according to claim 2, wherein a part of the insulating sheet is overlapped on the laminated surface of the electrode assembly.   The power storage device according to claim 3, wherein a portion of the insulating sheet that overlaps the laminated surface has irregularities. The electrode has a tab at the end, the tab being on the opposing surface of the electrode assembly;
It is arranged between the electrode assembly and the case, and includes a conductive member joined to both the tab and a terminal penetrating the case,
The insulating sheet is wound around the electrode assembly in a state of covering the electrode assembly together with the conductive member and the tab,
In the insulating sheet, the length of the portion covering the conductive member and the tab in the direction orthogonal to both the facing direction and the electrode stacking direction is the length of the portion covering the stack surface of the electrode assembly. Shorter than the length in the direction orthogonal to both the opposing direction and the stacking direction of the electrodes,
5. The power storage device according to claim 2, wherein a part of the conductive member protrudes from an opening end of the insulating sheet and is joined to the terminal at the protruding portion.   2. The power storage device according to claim 1, wherein a surface of each surface of the electrode assembly other than a surface opposite to the facing surface is covered with the insulating sheet, and a surface opposite to the facing surface is exposed. apparatus.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.