Secondary batteries

Abstract

This technology provides a way to suppress damage to the housing components. [Solution] The secondary battery 100 comprises a plurality of cells 10 stacked in a first direction, and a housing member 42 that houses the plurality of cells and electrolyte. The cell 10 has a first electrode foil 12, a positive electrode layer 14, a separator 16, a negative electrode layer 18, and a second electrode foil 20 stacked in a first direction. A first sealing member 21 and a spacer 26 are arranged between the first electrode foil and the separator, and on the outer circumference side of the edge of the positive electrode layer in a second direction. A second sealing member 22 is arranged between the second electrode foil and the separator, on the outer circumference side of the edge of the negative electrode layer in a second direction. The secondary battery has at least one of a first gas absorbent 30 provided between the positive electrode layer and the spacer in a second direction, a second gas absorbent 32 provided in the portion surrounded by the first sealing member, the spacer and the first electrode foil, and a third gas absorbent 34 provided between the negative electrode layer and the second sealing member in a second direction.

Description

Technical Field

[0004] , ,

[0005] , ,

[0001] The technology disclosed in this specification relates to secondary batteries.

Background Art

[0002] The secondary battery disclosed in Patent Document 1 has a plurality of stacked cells, an electrolytic solution, and a housing member made of a film. The secondary battery has a structure in which a plurality of cells and the electrolytic solution are sealed with the housing member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Gas is generated from the electrolytic solution during charging and discharging of the secondary battery. The internal pressure of the housing member may increase due to the generated gas, and the housing member may be damaged. In this specification, a technology for suppressing damage to the housing member is proposed.

Means for Solving the Problems

[0005] [[ID=4The secondary battery disclosed herein comprises a plurality of cells stacked in a first direction, and a housing member made of a film that houses the plurality of cells and an electrolyte. Each of the cells has a first electrode foil, a positive electrode layer, a separator, a negative electrode layer, and a second electrode foil stacked in the first direction. The separator is disposed between the first electrode foil and the second electrode foil. The positive electrode layer is sandwiched between the first electrode foil and the separator. The negative electrode layer is sandwiched between the second electrode foil and the separator. In a second direction perpendicular to the first direction, the ends of the first electrode foil and the ends of the separator are located further outward than the ends of the positive electrode layer. In the second direction, the ends of the second electrode foil and the ends of the separator are located further outward than the ends of the negative electrode layer. In the second direction, the ends of the negative electrode layer are located further outward than the ends of the positive electrode layer. A first sealing member and a spacer are positioned between the first electrode foil and the separator, on the outer circumferential side of the end of the positive electrode layer in the second direction. The first sealing member is positioned on the outer circumferential side of the end of the negative electrode layer in the second direction and is in contact with the first electrode foil. The spacer extends from a position overlapping the negative electrode layer to a position overlapping the first sealing member when viewed along the first direction, and is sandwiched between the first electrode foil and the separator at the position overlapping the negative electrode layer, and sandwiched between the first sealing member and the separator at the position overlapping the first sealing member. A second sealing member is positioned between the second electrode foil and the separator, on the outer circumferential side of the end of the negative electrode layer in the second direction, and is sandwiched between the second electrode foil and the separator. The secondary battery disclosed herein comprises at least one of a first gas absorbent provided between the positive electrode layer and the spacer in the second direction, a second gas absorbent provided in the portion surrounded by the first sealing member, the spacer and the first electrode foil, and a third gas absorbent provided between the negative electrode layer and the second sealing member in the second direction.

[0006] Furthermore, "outer periphery" refers to the side closer to the outer edge of the secondary battery when viewed along the first direction.

[0007] The above secondary battery includes at least one of the following: a first gas absorbent provided between the positive electrode layer and the spacer in the second direction; a second gas absorbent provided in the portion surrounded by the first sealing member, the spacer, and the first electrode foil; and a third gas absorbent provided between the negative electrode layer and the second sealing member in the second direction. Therefore, when gas is generated from the electrolyte, the gas inside the secondary battery is absorbed by at least one of the first gas absorbent, the second gas absorbent, and the third gas absorbent. As a result, the internal pressure of the housing member does not easily rise, and damage to the housing member is suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the secondary battery in the example. [Figure 2] This is an explanatory diagram of the manufacturing method for the secondary battery in the example. [Figure 3] This is an explanatory diagram of the manufacturing method for the secondary battery in the example. [Figure 4] This is an explanatory diagram of the manufacturing method for the secondary battery in the example. [Figure 5] This is an explanatory diagram of the manufacturing method for the secondary battery in the example. [Figure 6] This is an explanatory diagram of the manufacturing method for the secondary battery in the example. [Figure 7] This is an explanatory diagram of the manufacturing method for the secondary battery in the example. [Modes for carrying out the invention]

[0009] (Structure of secondary battery 100) The secondary battery 100 shown in Figure 1 is installed, for example, in an electric vehicle. The secondary battery 100 is, for example, a lithium-ion battery. The secondary battery 100 has a battery stack 90 and a housing member 42. The battery stack 90 is composed of a plurality of stacked cells 10. The housing member 42 houses the battery stack 90 and the electrolyte. The battery stack 90 is immersed in the electrolyte. The electrolyte is composed of a Class I petroleum product (for example, methyl propionate).

[0010] Multiple cells 10 have a roughly plate-like shape extending in the x and y directions and are stacked in the z direction. As shown in Figure 1, each cell 10 has a first electrode foil 12, a positive electrode layer 14, a separator 16, a negative electrode layer 18, and a second electrode foil 20. These are stacked from top to bottom in the order of the first electrode foil 12, positive electrode layer 14, separator 16, negative electrode layer 18, and second electrode foil 20.

[0011] The first electrode foil 12 is made of a conductive material. Examples of conductive materials for the first electrode foil 12 include aluminum.

[0012] The positive electrode layer 14 is in contact with the lower surface of the first electrode foil 12. The positive electrode layer 14 is a layer containing a positive electrode active material. Examples of positive electrode active materials include Li, LiCoO2, and LiNiO2. The positive electrode active material may be composed of one type of material or multiple types of materials. The positive electrode layer 14 is immersed in an electrolyte solution.

[0013] The separator 16 is in contact with the lower surface of the positive electrode layer 14. The separator 16 is made of a material that allows the charge carrier (in this case, lithium ions) to pass through. Examples of materials for the separator 16 include polypropylene and polyethylene. The separator 16 is permeated with an electrolyte solution.

[0014] The negative electrode layer 18 is in contact with the lower surface of the separator 16. The negative electrode layer 18 is a layer containing a negative electrode active material. Examples of the negative electrode active material include carbon materials such as graphite, hard carbon, and soft carbon. The negative electrode active material may be composed of one type of material or a plurality of types of materials. Further, the negative electrode layer 18 is impregnated with an electrolytic solution.

[0015] The second electrode foil 20 is in contact with the lower surface of the negative electrode layer 18. The second electrode foil 20 is in contact with the upper surface of the first electrode foil 12 of the adjacent cell 10. The second electrode foil 20 is composed of a conductive material. Examples of the conductive material of the second electrode foil 20 include copper.

[0016] As described above, the separator 16 is disposed between the first electrode foil 12 and the second electrode foil 20. The positive electrode layer 14 is sandwiched between the first electrode foil 12 and the separator 16. The negative electrode layer 18 is sandwiched between the second electrode foil 20 and the separator 16.

[0017] Hereinafter, when the secondary battery 100 is viewed in plan along the z direction, the side closer to the outer peripheral end 42a of the housing member 42 (that is, the side from the center of the secondary battery 100 toward the outer peripheral end 42a) is referred to as the outer peripheral side.

[0018] In the x direction and the y direction, the negative electrode layer 18 is larger than the positive electrode layer 14, the first electrode foil 12 and the second electrode foil 20 are larger than the negative electrode layer 18, and the separator 16 is larger than the first electrode foil 12 and the second electrode foil 20. For this reason, in the x direction and the y direction, the end portion 16a of the separator 16 is disposed on the outer peripheral side with respect to the end portion 12a of the first electrode foil 12 and the end portion 20a of the second electrode foil 20. Further, in the x direction and the y direction, the end portion 12a of the first electrode foil 12 and the end portion 20a of the second electrode foil 20 are disposed on the outer peripheral side with respect to the end portion 18a of the negative electrode layer 18. Further, in the x direction and the y direction, the end portion 18a of the negative electrode layer 18 is disposed on the outer peripheral side with respect to the end portion 14a of the positive electrode layer 14.

[0019] Cell 10 has a spacer 26 in a frame shape. The spacer 26 is made of a resin material. The spacer 26 is disposed between the first electrode foil 12 and the separator 16. The spacer 26 is in contact with the upper surface of the separator 16. In the x - direction and y - direction, the spacer 26 is disposed on the outer - peripheral side of the end portion 14a of the positive - electrode layer 14. An interval C1 is provided between the spacer 26 and the positive - electrode layer 14. When viewed along the z - direction, the spacer 26 extends from the position overlapping the negative - electrode layer 18 to the end portion 16a of the separator 16. At the position overlapping the negative - electrode layer 18, the spacer 26 is sandwiched between the lower surface of the first electrode foil 12 and the upper surface of the separator 16. The spacer 26 and the separator 16 are displaced downward on the outer - peripheral side of the negative - electrode layer 18. Therefore, an interval is provided between the upper surface of the spacer 26 and the lower surface of the first electrode foil 12 at the outer - peripheral portion of the spacer 26.

[0020] Cell 10 has a seal member 23. The seal member 23 is made of a resin material. The seal member 23 covers the outer - peripheral edge of the battery stack 90 (i.e., a plurality of cells 10). The seal member 23 has a first portion 21 that seals between the first electrode foil 12 and the spacer 26, and a second portion 22 that seals between the separator 16 and the second electrode foil 20.

[0021] The first portion 21 is sandwiched between the lower surface of the first electrode foil 12 and the upper surface of the spacer 26. In the x and y directions, the first portion 21 is positioned on the outer circumference of the edge 14a of the positive electrode layer 14 and the edge 18a of the negative electrode layer 18. When viewed along the z direction, the spacer 26 extends from a position overlapping with the negative electrode layer 18 to a position overlapping with the first portion 21. At the position overlapping with the first portion 21, the spacer 26 is sandwiched between the lower surface of the first portion 21 and the upper surface of the separator 16. A gap is provided between the region where the spacer 26 is in contact with the first electrode foil 12 and the region where the first portion 21 is in contact with the first electrode foil 12, and a space C2 is provided within this gap. Space C2 is the space enclosed by the first electrode foil 12, the spacer 26, and the first portion 21. The upper surface of space C2 is formed by the first electrode foil 12, the outer peripheral side surface of space C2 is formed by the first part 21, and the lower surface of space C2 is formed by the spacer 26.

[0022] The second portion 22 is sandwiched between the upper surface of the second electrode foil 20 and the lower surface of the separator 16. In the x and y directions, the second portion 22 is positioned on the outer periphery of the cell 10, beyond the edge 18a of the negative electrode layer 18. A gap C3 is provided between the second portion 22 and the negative electrode layer 18.

[0023] The secondary battery 100 includes a first gas absorbent 30, a second gas absorbent 32, and a third gas absorbent 34. Examples of the first gas absorbent 30, the second gas absorbent 32, and the third gas absorbent 34 include porous materials (e.g., activated carbon) and polymer materials. The first gas absorbent 30, the second gas absorbent 32, and the third gas absorbent 34 can absorb gas generated from the electrolyte. The first gas absorbent 30 is provided in the space C1. The second gas absorbent 32 is provided in the space C2. The third gas absorbent 34 is provided in the space C3. The first gas absorbent 30, the second gas absorbent 32, and the third gas absorbent 34 may be permeated with the electrolyte. Furthermore, the secondary battery 100 only needs to have at least one of the first gas absorbent 30, the second gas absorbent 32, and the third gas absorbent 34.

[0024] The housing member 42 has a first film 44 and a second film 46. The outer edge 44a of the first film 44 and the outer edge 46a of the second film 46 are welded together.

[0025] The first film 44 has a current collector plate 48 and a first film material 50. The current collector plate 48 is made of a conductive material. Examples of conductive materials for the current collector plate 48 include aluminum and copper. The current collector plate 48 is electrically connected to the first electrode foil 12 of the cell 10 located at the top of the battery stack 90 via the second electrode foil 20. The first film material 50 is made of a film (in this case, a laminate film). The first film material 50 is insulated from the current collector plate 48.

[0026] The second film 46 has a current collector plate 52 and a second film material 54. The current collector plate 52 is made of a conductive material. Examples of conductive materials for the current collector plate 52 include aluminum and copper. The current collector plate 52 is electrically connected to the second electrode foil 20 of the cell 10 located at the bottom of the battery stack 90 via the first electrode foil 12. The second film material 54 is made of a film (in this case, a laminate film). The second film material 54 is insulated from the current collector plate 52.

[0027] During charging and discharging of the secondary battery 100, gas is generated from the electrolyte. If the first gas absorbent 30, the second gas absorbent 32, and the third gas absorbent 34 are not present, the generated gas will accumulate in the housing member 42. As a result, the internal pressure of the housing member 42 will increase, causing the housing member 42 to break. In contrast, in the above-described embodiment, the first gas absorbent 30, the second gas absorbent 32, and the third gas absorbent 34 can absorb the gas generated from the electrolyte. Therefore, damage to the housing member 42 can be suppressed.

[0028] Furthermore, if the second gas absorbent 32 is not provided in space C2, the weight of the first electrode foil 12 may cause buckling and wrinkles to form in the first electrode foil 12. Under low or high temperature conditions, the first electrode foil 12 may experience metal fatigue due to expansion and contraction, and there is a risk that the first electrode foil 12 may break due to buckling and wrinkles. In contrast, in the above-described embodiment, the second gas absorbent 32 is provided in space C2. Therefore, the first electrode foil 12 is less prone to buckling and wrinkles.

[0029] (Manufacturing method for secondary battery 100) Next, the manufacturing method of the secondary battery 100 will be described. First, as shown in Figure 2, electrode foil 60 and sealing material 62 are prepared. The electrode foil 60 is made by laminating a first electrode foil 12 and a second electrode foil 20 together. The sealing material 62 is made to cover the edges of the electrode foil 60.

[0030] Next, as shown in Figure 3, the negative electrode layer 18 is positioned in contact with the upper surface of the first electrode foil 12. In the x and y directions, the negative electrode layer 18 is positioned at a distance from the sealing material 62. Next, the third gas absorbent 34 is placed between the negative electrode layer 18 and the sealing material 62.

[0031] Next, as shown in Figure 4, the separator 16 is positioned so as to be in contact with the upper surface of the negative electrode layer 18 and the upper surface of the third gas absorbent 34. Then, the spacer 26 is positioned so as to be in contact with the upper surface of the separator 16. In the z direction, one end of the spacer 26 is positioned to overlap with the negative electrode layer 18, and the other end of the spacer 26 is positioned to overlap with the sealing material 62.

[0032] Next, as shown in Figure 5, the first gas absorbent 30 and the second gas absorbent 32 are placed. The first gas absorbent 30 is placed so as to be in contact with the upper surface of the separator 16 and the end of the spacer 26. The second gas absorbent 32 is placed so as to be in contact with the upper surface of the spacer 26. Then, the positive electrode layer 14 is placed so as to be in contact with the upper surface of the separator 16. The first gas absorbent 30 is placed between the positive electrode layer 14 and the spacer 26. The manufacturing cell 70 is manufactured by the process described above.

[0033] Next, the manufacturing cells 70 are stacked in the z direction. Then, as shown in Figure 6, the inside of the stacked manufacturing cells 70 is depressurized. This causes the insides of the stacked manufacturing cells 70 to adhere tightly. By stacking multiple manufacturing cells 70 in this way, a structure is formed in which cells 10 function as a battery are stacked.

[0034] Next, as shown in Figure 7, a sealing member 23 is formed by welding each sealing material 62 together. Then, electrolyte is injected into each cell 10 through an injection port (not shown). Next, the battery stack 90 is sandwiched between the first film 44 and the second film 46. The battery stack 90 and electrolyte are housed in the housing member 42 by welding the outer edge 44a of the first film 44 and the outer edge 46a of the second film 46 together. The housing member 42 and the cells 10 are brought into close contact by reducing the pressure inside the housing member 42. This makes it possible to obtain the secondary battery 100 shown in Figure 1.

[0035] Part 1 21 is an example of the "first sealing member". Part 2 22 is an example of the "second sealing member".

[0036] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness. [Explanation of symbols]

[0037] 10: Cell, 12: First electrode foil, 12a: End, 14: Positive electrode layer, 14a: End, 16: Separator, 16a: End, 18: Negative electrode layer, 18a: End, 20: Second electrode foil, 20a: End, 21: First part, 22: Second part, 23: Sealing member, 26: Spacer, 30: First gas absorbent, 32: Second gas absorbent, 34: Third gas absorbent, 42: Housing member, 100: Secondary battery

Claims

[Claim 1] It is a secondary battery, Multiple cells stacked in the first direction, It is made of a film and contains a housing member that houses the plurality of cells and the electrolyte, Equipped with, Each of the cells has a first electrode foil, a positive electrode layer, a separator, a negative electrode layer, and a second electrode foil stacked in the first direction. The separator is positioned between the first electrode foil and the second electrode foil. The positive electrode layer is sandwiched between the first electrode foil and the separator. The negative electrode layer is sandwiched between the second electrode foil and the separator. In a second direction perpendicular to the first direction, the end of the first electrode foil and the end of the separator are positioned on the outer circumference side of the end of the positive electrode layer. In the second direction, the end of the second electrode foil and the end of the separator are positioned on the outer circumference side of the end of the negative electrode layer. In the second direction, the end of the negative electrode layer is positioned on the outer circumference side of the end of the positive electrode layer, The first sealing member and the spacer are arranged between the first electrode foil and the separator, and in the second direction, on the outer circumference side of the end of the positive electrode layer. The first sealing member is positioned on the outer circumference side of the end of the negative electrode layer in the second direction and is in contact with the first electrode foil. The spacer extends from a position overlapping the negative electrode layer to a position overlapping the first sealing member when viewed along the first direction, is sandwiched between the first electrode foil and the separator at the position overlapping the negative electrode layer, and is sandwiched between the first sealing member and the separator at the position overlapping the first sealing member. A second sealing member is positioned between the second electrode foil and the separator, and in the second direction, on the outer circumference side of the end of the negative electrode layer, and is sandwiched between the second electrode foil and the separator. The present invention comprises at least one of a first gas absorbent provided between the positive electrode layer and the spacer in the second direction, a second gas absorbent provided in the portion surrounded by the first sealing member, the spacer, and the first electrode foil, and a third gas absorbent provided between the negative electrode layer and the second sealing member in the second direction. Secondary battery.

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