JP2017135022A - Electricity storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electricity storage device capable of suppressing a part of an electrode from scattering through a cleaved pressure release valve during a nail penetration test.SOLUTION: A secondary battery 10 including a pressure release valve 20 includes a plural sheets of thickness adjustment members 50 between an end face 44 and a long side wall 12d of an electrode assembly 14. The secondary battery 10 has an exhaust passage 60 penetrating through the plural sheets of thickness adjustment members 50 in a lamination direction and extending in a surface direction of the thickness adjustment members 50. A downstream end of the exhaust passage 60 in a gas circulation direction opens toward the pressure release valve 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device having a pressure release valve.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. For example, as described in Patent Document 1, the secondary battery includes an electrode assembly and an electrolytic solution housed in a case, and a pressure release valve that releases the pressure inside the case to the outside of the case on the wall surface of the case. Is provided.

Japanese Patent No. 4881409

  In such a secondary battery, when a nail penetration test, which is one of the evaluation tests, is performed, the separator between the positive electrode and the negative electrode is broken by the nail, and the positive electrode and the negative electrode are short-circuited in the case. To do. When a short circuit occurs, heat is generated around the short circuit part, the electrolyte component is decomposed by the heat generated around the short circuit part, and gas is generated in the case. Then, the pressure in the case rises and the pressure release valve is opened, but when the gas is released from the pressure release valve to the outside of the case, a part of the electrode is scraped off by the high pressure gas, and it gets on the gas as it is. There is a risk of splashing outside.

  An object of the present invention is to provide a power storage device that can suppress a part of an electrode from being scattered from a cleaved pressure release valve during a nail penetration test.

  A power storage device for solving the above problems includes an electrode assembly configured in layers with electrodes having different polarities insulated by a separator, an electrolytic solution, and a case for housing the electrode assembly and the electrolytic solution. A plurality of sheet members stacked in the stacking direction of the electrode assembly, and present in the wall portion of the case, and cleaved when the pressure in the case reaches the open pressure, And a pressure release valve that opens to the outside, the power storage device having an exhaust passage that penetrates the plurality of sheet members in the stacking direction and extends in a surface direction of the sheet members, and the exhaust passage The gist of the present invention is that the downstream end in the gas flow direction is opened toward the pressure release valve.

  According to this, when a nail penetration test which is one of the evaluation tests of the power storage device is performed, the separator between the electrodes of different polarities is broken by the nail stuck along the stacking direction of the electrode assembly from the case. However, the electrodes having different polarities are short-circuited in the case. When a short circuit occurs, heat is generated around the short circuit part, the electrolyte component is decomposed by the heat generated around the short circuit part, and gas is generated in the case. Then, the pressure in the case rises and the pressure relief valve is opened. Further, the gas generated in the short-circuit portion flows along the stacking direction toward the exhaust passage that is a large space. Then, the gas rises along the exhaust passage, flows from the downstream end of the exhaust passage toward the pressure release valve, and is released out of the case through the cleaved pressure release valve. That is, the high-pressure gas generated in the vicinity of the short-circuit portion can be concentrated in the exhaust passage and collectively raised in the exhaust passage. For this reason, the gas which generate | occur | produced in the short circuit part vicinity is not collected, but the electrode exposed to a high voltage | pressure gas reduces compared with the case where it raises in the electrode assembly from the short circuit part as it is. As a result, during the nail penetration test, the number of electrodes scraped by the generated high-pressure gas is reduced, and it is possible to suppress the part of the electrodes from being scattered outside the case.

In the power storage device, an upstream end of the exhaust passage in the gas flow direction may open at a central portion of the electrode.
According to this, in the nail penetration test, the nail is stuck near the central portion of the electrode, and the short-circuit portion is generated at the central portion of the electrode. By opening the upstream end in the gas flow direction in the exhaust passage in the vicinity of the short-circuit portion, the generated gas quickly flows into the exhaust passage. For this reason, the gas generated in the short-circuit portion can be quickly flowed to the pressure release valve via the exhaust passage.

In the power storage device, the exhaust passage may exist between an end face located at least one end in the stacking direction of the electrode assembly and a side wall of the case facing the end face.
According to this, the nail is first stuck at the end of the electrode assembly in the stacking direction. For this reason, the gas is first generated at the end of the electrode assembly in the stacking direction. Since the exhaust passage is present at the end in the stacking direction, the generated gas can be quickly flowed into the exhaust passage.

  The power storage device is a secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a part of electrode scatters from the pressure release valve which broke at the time of a nail penetration test.

The disassembled perspective view which shows the secondary battery of embodiment. The perspective view which shows the external appearance of the secondary battery of embodiment. The disassembled perspective view which shows an electrode assembly and a thickness adjustment member. The perspective view which shows the electrode assembly integrated with the thickness adjustment member. Sectional drawing which shows the inside of a secondary battery. The fragmentary sectional view which shows a nail penetration test.

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the secondary battery 10 is a lithium ion secondary battery, and has a metal case 11 that forms the outline thereof. The case 11 includes a bottomed rectangular parallelepiped container 12 having an opening 12a on one surface and a lid 13 that closes the opening 12a. The container 12 has a rectangular bottom plate 12b, a short side wall 12c erected from a pair of opposed short side edges of the bottom plate 12b, and a long side wall 12d erected from a pair of opposed long side edges of the bottom plate 12b. Have The case 11 contains an electrode assembly 14 and an electrolytic solution (not shown). The electrode assembly 14 has a rectangular parallelepiped shape as a whole, corresponding to the internal space of the container 12 having a rectangular parallelepiped shape. An insulating film 15 is provided on the inner surface of the container 12.

  The secondary battery 10 includes a pressure release valve 20 on a lid 13 as a wall portion of the case 11. The pressure release valve 20 is cleaved when the pressure in the case 11 reaches an open pressure that is a predetermined pressure so that the pressure in the case 11 does not increase excessively, and the pressure in the case 11 is moved out of the case 11. Open. The release pressure of the pressure release valve 20 is set to a pressure at which the case 11 itself and the joint between the container 12 and the lid 13 can be broken before a crack or breakage occurs. The pressure release valve 20 has a thin plate-like valve body 20 a that is thinner than the plate thickness of the lid 13. The valve body 20 a is located at the bottom of a recess 13 b that is recessed on the surface of the lid 13, and is molded integrally with the lid 13. In the pressure release valve 20, the surface on the valve body 20 a is a part of the surface of the lid 13 of the case 11. Further, the pressure release valve 20 has a cleavage groove 20b on the surface of the valve body 20a. The valve body 20 a is located at the center of the lid 13.

  As shown in FIG. 3, the electrode assembly 14 is made of a rectangular sheet-like positive electrode 21 and a rectangular sheet-like negative electrode 22, and is made of a resin and is porous so that ions (lithium ions) related to electric conduction can pass therethrough. And a separator 23 formed of a material film. The positive electrode 21 includes a rectangular positive electrode metal foil (aluminum foil in this embodiment) 21a and a rectangular positive electrode active material layer 21b provided on both surfaces (surfaces) of the positive electrode metal foil 21a. . The positive electrode 21 includes a first side 21c on one long side. The positive electrode 21 includes a positive electrode current collecting tab 41 having a shape protruding from a part of the first side 21c. The positive electrode 21 includes a second side 21d on the long side opposite to the first side 21c. Further, the positive electrode 21 includes a third side 21e on a short side connecting one end of the first side 21c and one end of the second side 21d, and the other end of the first side 21c and the second side 21d. A fourth side 21f is provided on the short side connecting the other end of the second side.

  The negative electrode 22 has a rectangular negative electrode metal foil (copper foil in this embodiment) 22a and a rectangular negative electrode active material layer 22b provided on both surfaces (surfaces) of the negative electrode metal foil 22a. . The negative electrode 22 includes a first side 22c on one long side. The negative electrode 22 includes a negative electrode current collecting tab 42 having a shape protruding from a part of the first side 22c. The negative electrode 22 includes a second side 22d on the long side opposite to the first side 22c. Further, the negative electrode 22 includes a third side 22e on a short side connecting one end of the first side 22c and one end of the second side 22d, and the other end of the first side 22c and the second side 22d. A fourth side 22f is provided on the short side connecting the other ends of the second side 22f.

  As shown in FIG. 1, the electrode assembly 14 has rectangular end faces 44 on both sides in the stacking direction, and each end face 44 is constituted by a negative electrode 22. The electrode assembly 14 includes a first side 21c of the positive electrode 21, a first side 22c of the negative electrode 22, and a tab side end face 36 in which one side of the separator 23 along the first sides 21c and 22c is gathered. Have The electrode assembly 14 includes a second side 21d of the positive electrode 21, a second side 22d of the negative electrode 22, and a bottom surface 37 on which one side of the separator 23 along the second sides 21d and 22d gathers. The electrode assembly 14 has a side surface 38 on a surface excluding the tab side end surface 36 and the bottom surface 37 among the four surfaces connected to the end surface 44. One side surface 38 of the electrode assembly 14 is formed by gathering the third side 21e of the positive electrode 21, the third side 22e of the negative electrode 22, and one side of the separator 23 along the third sides 21e and 22e. Has been. The other side surface 38 of the electrode assembly 14 is formed by gathering the fourth side 21f of the positive electrode 21, the fourth side 22f of the negative electrode 22, and one side of the separator 23 along the fourth sides 21f and 22f. Has been.

  As shown in FIGS. 1 and 4, the positive electrode 21, the negative electrode 22, and the separator 23 are arranged such that the positive electrode current collecting tabs 41 are arranged in a line along the stacking direction and do not overlap the positive electrode current collecting tabs 41. The negative electrode current collecting tabs 42 are stacked at the position so as to be arranged in a line along the stacking direction. The positive electrode current collecting tab 41 and the negative electrode current collecting tab 42 are positioned on the tab side end surface 36 of the electrode assembly 14. On the tab side end surface 36, each positive electrode current collection tab 41 and each negative electrode current collection tab 42 are bent in a state of being collected (bundled) within a range from one end to the other end in the stacking direction of the electrode assembly 14. ing. Each positive current collecting tab 41 is electrically connected by welding a portion where each positive current collecting tab 41 overlaps, and a positive electrode conductive member 61 is connected to the positive current collecting tab 41. A positive electrode terminal 51 for taking out electricity from the electrode assembly 14 is connected to the positive electrode conductive member 61.

  Similarly, the negative electrode current collecting tabs 42 are electrically connected by welding the portions where the negative electrode current collecting tabs 42 are overlapped, and the negative electrode conductive member 62 is connected to the negative electrode current collecting tabs 42. A negative electrode terminal 52 for taking out electricity from the electrode assembly 14 is connected to the negative electrode conductive member 62. The positive terminal 51 and the negative terminal 52 penetrate the lid 13 and protrude out of the case 11, and the positive terminal 51 and the negative terminal 52 are insulated from the lid 13 by the insulating ring 13a.

  In the container 12, when the shortest distance between the insulating films 15 of the pair of long side walls 12d facing each other with the electrode assembly 14 interposed therebetween is the inner dimension of the container 12, the length of the electrode assembly 14 in the stacking direction is as follows. Slightly smaller than the inner dimensions. This is because when a predetermined number of positive electrodes 21, negative electrodes 22, and separators 23 are stacked, the electrode assembly 14 can be accommodated in the case 11 even if the actual thickness takes the maximum manufacturing tolerance. , Because each thickness is set.

  A thickness adjusting member 50 as a sheet member is interposed between both end faces 44 of the electrode assembly 14 and a long side wall 12 d (insulating film 15) as a side wall facing each end face 44. The thickness adjusting member 50 is a resin film having a predetermined thickness. The thickness adjusting member 50 corresponds to the length of the electrode assembly 14 in the stacking direction, and a plurality of the thickness adjusting members 50 are stacked.

  As shown in FIG. 4, in the electrode assembly 14, a large number of positive electrodes 21, negative electrodes 22, separators 23, and a plurality of thickness adjusting members 50 are fixed to each other by a plurality of holding tapes 45. By using the thickness adjusting member 50, the length in the stacking direction of the electrode assembly 14 and the thickness adjusting member 50 is adjusted within a predetermined range.

  As shown in FIG. 3, each thickness adjusting member 50 has a shape along the outer shape of the separator 23. The thickness adjusting member 50 includes a first side 50 a along the first side 21 c of the positive electrode 21 and the first side 22 c of the negative electrode 22, and the second side 21 d of the positive electrode 21 and the negative electrode 22. The second side 50b is provided along the second side 22d. The thickness adjusting member 50 includes a third side 21e along the third side 21e of the positive electrode 21 and a third side 22e along the negative electrode 22, and a fourth side 21f of the positive electrode 21; A fourth side 50 d is provided along the fourth side 22 f of the negative electrode 22. The first side 50 a of the thickness adjusting member 50 exists on a surface along the tab side end surface 36 and faces the lid 13.

  As shown in FIG. 1, the thickness adjusting member 50 includes a passage forming portion 50 f that is recessed from the first side 50 a facing the lid 13 toward the second side 50 b. The passage forming portion 50 f has a shape that penetrates the thickness adjusting member 50 in the thickness direction and extends in the surface direction of the thickness adjusting member 50. Further, one end of the passage forming portion 50 f is opened in the middle of the first side 50 a, and the other end is located at the center portion of the thickness adjusting member 50. The passage forming portion 50f has a shape that extends straight between the first side 50a of the thickness adjusting member 50 and the central portion with a constant width.

  The secondary battery 10 includes an exhaust passage 60 formed by stacking a plurality of passage forming portions 50f in the stacking direction. The exhaust passage 60 penetrates the plurality of thickness adjusting members 50 in the thickness direction, and the thickness adjusting member. The shape extends in the direction of 50 planes.

  As shown in FIG. 5, one end of the exhaust passage 60 opens at the upper end surface (tab side end surface 36) of the electrode assembly 14, and the other end of the exhaust passage 60 is at the center of the end surface 44 of the electrode assembly 14. It is open. Since the central portion of the end surface 44 of the electrode assembly 14 is also the central portion of the positive electrode 21 and the negative electrode 22, the other end of the exhaust passage 60 is open to the central portion of the positive electrode 21 and the negative electrode 22. become.

  Gas generated when the electrode assembly 14 is short-circuited flows into the exhaust passage 60. Since the gas rises, the downstream end of the exhaust passage 60 in the gas flow direction G opens at the tab side end surface 36 that is the upper end surface of the electrode assembly 14, and the pressure release valve of the lid 13 that faces the tab side end surface 36. It opens toward 20. Further, the upstream end of the exhaust passage 60 in the gas flow direction G is open at the center of the end surface 44 of the electrode assembly 14 which is the center of the positive electrode 21 and the negative electrode 22.

  In the secondary battery 10, since the thickness adjusting member 50 is interposed between both end surfaces 44 of the electrode assembly 14 and the long side walls 12 d, the exhaust passage 60 is connected to the end surface of the electrode assembly 14. 44 and the long side wall 12d.

Next, the effect | action of the secondary battery 10 is described with an effect.
As shown in FIG. 6, when a nail F is inserted into any of the long side walls 12d in order to perform a nail penetration test, the nail F is inserted into the central portion of the end surface 44 of the electrode assembly 14, and the positive electrode 21 The negative electrode 22 and the central portion of the separator 23 are stuck. Then, the separator 23 between the positive electrode 21 and the negative electrode 22 is broken or melted via the nail F, and the positive electrode 21 and the negative electrode 22 are short-circuited in the case 11. At this time, the nail F is stuck near the upstream end of the exhaust passage 60 in the gas flow direction.

  When a short circuit occurs in the electrode assembly 14, heat is generated in the vicinity of the short circuit part, and the pressure in the secondary battery 10 is increased due to the generation of gas. When the internal pressure of the case 11 reaches the open pressure of the pressure release valve 20, the valve body 20a of the pressure release valve 20 is cleaved from the cleavage groove 20b, and the gas in the case 11 is released to the outside of the case 11.

  Further, the high-pressure gas generated in the short-circuit portion flows in the stacking direction along the nails F toward the exhaust passage 60 which is a large space, and is concentrated in the exhaust passage 60 as indicated by an arrow Y in FIG. . Then, the high-pressure gas collectively rises in the exhaust passage 60 and is released from the cleaved pressure release valve 20 to the outside of the case 11.

  Therefore, compared with the case where the gas generated in the vicinity of the short-circuit portion is not collected and ascends in the electrode assembly 14 as it is, by providing the exhaust passage 60, the positive electrode 21 exposed to the high-pressure gas and The number of negative electrodes 22 decreases. As a result, it is possible to suppress a part of the positive electrode 21 and the negative electrode 22 from being scraped by the high-pressure gas, and it is possible to suppress a part of the electrode from being scattered as the gas is released to the outside of the case 11.

  The exhaust passage 60 has an upstream end in the gas flow direction G opened at the center of the end surface 44 of the electrode assembly 14. For this reason, in the nail penetration test, when the nail F is stuck in the central portion of the end surface 44 of the electrode assembly 14 and gas is generated, the gas can be quickly flowed into the exhaust passage 60 along the nail F. Therefore, the positive electrode 21 and the negative electrode 22 that are exposed to high-pressure gas can be reduced.

  In addition, the exhaust passage 60 exists between each end face 44 of the electrode assembly 14 and each long side wall 12d. During the nail penetration test, gas is first generated near the end face 44 where the nail F first penetrates. For this reason, the exhaust passage 60 exists in the immediate vicinity of the place where the gas is first generated, and the generated gas can be quickly flowed into the exhaust passage 60.

  The exhaust passage 60 is formed by laminating the passage forming portions 50 f of the thickness adjusting member 50. The thickness adjusting member 50 is a member for adjusting the length of the electrode assembly 14 and the thickness adjusting member 50 in the stacking direction within a predetermined range. Therefore, the thickness adjusting member 50 is a member that does not contribute to the performance of the secondary battery 10. Therefore, the exhaust passage 60 can be provided in the case 11 without changing the performance of the secondary battery 10 and without increasing the number of parts.

  And since the exhaust passage 60 is formed by laminating the passage forming portions 50f of the thickness adjusting members 50, the exhaust passage 60 can be formed even if the number of the thickness adjusting members 50 is different.

  The thickness adjusting member 50 is integrated with the electrode assembly 14 by the holding tape 45. Therefore, the exhaust passage 60 formed by the thickness adjusting member 50 can also be provided integrally with the electrode assembly 14, and the gas generated from the electrode assembly 14 can easily flow toward the exhaust passage 60.

  The thickness adjusting members 50 are disposed on both sides of the electrode assembly 14 in the stacking direction, and the exhaust passages 60 are also present on both sides of the electrode assembly 14 in the stacking direction. For this reason, even if the nail F stabs from any of the lamination directions of the electrode assembly 14, it can suppress that a gas flows into the exhaust passage 60 and the positive electrode 21 and the negative electrode 22 are exposed to a high pressure gas.

In addition, you may change the said embodiment as follows.
The thickness adjusting member 50 is not interposed between the end face 44 of the electrode assembly 14 and the long side wall 12d, but is interposed in the middle of the stacking direction of the electrode assembly 14, and a plurality of members in the middle of the stacking direction. The exhaust passage 60 may be provided by laminating the passage forming portions 50 f of the sheet thickness adjusting members 50.

  When configured in this way, high-pressure gas generated in the vicinity of the short-circuit portion flows toward the exhaust passage 60 along the stacking direction, collects in the exhaust passage 60, and rises together. For this reason, the positive electrode 21 and the negative electrode 22 which are exposed to high-pressure gas decrease. As a result, the positive electrode 21 and the negative electrode 22 scraped by the generated high-pressure gas during the nail penetration test are reduced, and it is possible to suppress a part of them from being scattered outside the case 11.

  In the embodiment, the sheet member is embodied as the thickness adjusting member 50 that adjusts the dimension of the electrode assembly 14 in the stacking direction, but the sheet member is an insulating sheet that insulates the electrode assembly 14 from the container 12. Alternatively, it may be a short-circuiting electrode interposed between the electrode assembly 14 and the long side wall 12d.

  ○ The upstream end of the exhaust passage 60 in the gas flow direction G was opened at the center of the end surface 44 of the electrode assembly 14, but the upstream end of the exhaust passage 60 was opened at the nail set in the nail penetration test. You may change according to the place where F sticks. In this case, the downstream end of the exhaust passage 60 in the gas flow direction G is opened to the edge (first side 50a) facing the lid 13 where the pressure release valve 20 is located, and the exhaust passage 60 is downstream from the upstream end thereof. The shape extends straight to the end.

  The number of the thickness adjusting members 50 may be appropriately changed according to the dimensions of the end face 44 and the long side wall 12d. The flow passage cross-sectional area of the exhaust passage 60 is changed according to the number of stacked thickness adjusting members 50.

  In the embodiment, one end of the passage forming portion 50f is opened at the first side 50a of the thickness adjusting member 50, and the downstream end of the exhaust passage 60 in the gas flow direction G is the upper end surface (tab side end surface 36 of the electrode assembly 14). ), But not limited to this. One end of the passage forming portion 50 f is not opened at the first side 50 a of the thickness adjusting member 50, but is opened within the surface of the thickness adjusting member 50, and the downstream end of the exhaust passage 60 in the gas flow direction G in the electrode assembly 14. You may open in the end surface 44. FIG. In this case, for example, the pressure release valve 20 may be provided on the long side wall 12d located at the position facing the downstream end of the gas passage direction G in the exhaust passage 60, or the pressure release valve 20 may be provided on the lid 13.

  In the embodiment, one end of the passage forming portion 50f is opened at the first side 50a of the thickness adjusting member 50, and the downstream end of the exhaust passage 60 in the gas flow direction G is the upper end surface (tab side end surface 36 of the electrode assembly 14). ), But not limited to this. One end of the passage forming portion 50f is opened at the third side 50c and the fourth side 50d of the thickness adjusting member 50, and the downstream end of the exhaust passage 60 in the gas flow direction G is opened at the side surface 38 of the electrode assembly 14. You may let them.

The number of positive electrodes 21 and negative electrodes 22 constituting the electrode assembly 14 may be changed as appropriate.
The thickness adjusting member 50 is interposed only between one end surface 44 of the electrode assembly 14 and the long side wall 12d, and the exhaust passage 60 is only between the one end surface 44 of the electrode assembly 14 and the long side wall 12d. May be present.

The electrode assembly may be a wound type in which one belt-like positive electrode and one belt-like negative electrode are wound around a winding shaft in a state where they are insulated by a separator.
The power storage device may be another power storage device such as an electric double layer capacitor.

  In embodiment, although the secondary battery 10 was a lithium ion secondary battery, it is not restricted to this, Other secondary batteries, such as nickel hydride, may be sufficient. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(1) The power storage device, wherein the sheet member is a thickness adjusting member that adjusts a dimension of the electrode assembly in a stacking direction.

  G ... Gas flow direction, 10 ... Secondary battery as power storage device, 11 ... Case, 12d ... Long side wall as side wall, 13 ... Lid as wall part, 14 ... Electrode assembly, 20 ... Pressure release valve, 21 ... Positive electrode, 22 ... negative electrode, 23 ... separator, 44 ... end face, 50 ... thickness adjusting member as sheet member, 60 ... exhaust passage.

Claims (4)

An electrode assembly configured in layers with electrodes of different polarities insulated by separators;
An electrolyte,
A case for accommodating the electrode assembly and the electrolyte;
A plurality of sheet members stacked in the stacking direction of the electrode assembly;
A pressure release valve that is present in the wall of the case and is cleaved when the pressure in the case reaches an open pressure, and releases the pressure in the case to the outside of the case,
An exhaust passage extending through the plurality of sheet members in the stacking direction and extending in the surface direction of the sheet members;
A power storage device, wherein a downstream end of the exhaust passage in a gas flow direction opens toward the pressure release valve.   The power storage device according to claim 1, wherein an upstream end of the exhaust passage in a gas flow direction opens at a central portion of the electrode.   3. The power storage device according to claim 1, wherein the exhaust passage is present between an end face located at least one end in the stacking direction of the electrode assembly and a side wall of the case facing the end face.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a secondary battery.

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