Secondary batteries and films inside secondary battery cells

Abstract

To resolve a problem of reliability against vibration applied to a secondary battery in a conventional secondary battery.SOLUTION: A secondary battery cell 1 has: a wound body around which a positive electrode foil, a separator, and a negative electrode foil are wound in an overlapped state, being formed in a flat shape; a case 10 that accommodates the wound body; and an insulation film that wraps the wound body in a bag shape to insulate the wound body and the case from each other. The insulation film is formed with in-cell spacers 41 and 42 obtained by folding a film along a current collector 21 where the positive electrode foil or the negative electrode foil is bound in the wound body. The in-cell spacers are held in a gap between the current collector 21 and the case 10.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to, for example, secondary batteries and films inside secondary battery cells.

Background Art

[0002] For a secondary battery cell, a structure is used in which a wound body for storing electric power is housed in a case and sealed. At this time, since both the wound body and the case are conductive members, an insulating film as an insulating member is inserted between the wound body and the case. Further, in a secondary battery cell, it is required that the wound body does not displace inside the case when vibration is applied to the cell. Therefore, techniques for preventing displacement of the wound body in the case are disclosed in Patent Documents 1 and 2.

[0003] The secondary battery described in Patent Document 1 includes a battery case and a plurality of winding portions housed in the battery case and wound around a winding shaft. The winding shaft includes an electrode assembly arranged on the bottom surface of the battery case, and a deformation member formed between the electrode assembly and the bottom surface of the battery case and pressurized between the electrode assembly and the battery case.

[0004] In the battery described in Patent Document 2, the outer periphery of the electrode body is covered with a separator over the entire circumference, and an insulating film different from the separator of the electrode body is sandwiched between both flat portions of the electrode body and both maximum area surfaces of the internal space. The internal space of the outer case has a size for housing the electrode body without a gap in the thickness direction and with a gap in a direction other than the thickness direction. Holes are formed in the insulating film at positions within a range facing both flat portions and not overlapping the ends of the separator.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] The technology described in Patent Document 1 requires the use of a deformable member that is pressurized between the electrode assembly and the battery case, which presents a problem in that it is not possible to prevent displacement of the electrode body (e.g., the wound body) within the case when no pressurizing force is applied from the thickness direction of the battery cell. Similarly, Patent Document 2 also presents a problem in that it is not possible to prevent displacement of the electrode body (e.g., the wound body) within the case when no pressurizing force is applied from the thickness direction of the battery cell. In other words, Patent Documents 1 and 2 have a problem in that they cannot prevent displacement of the wound body within the case when no pressurizing force is applied from the thickness direction of the battery cell.

[0007] This invention has been made in view of the above circumstances, and aims to prevent the displacement of the wound body within the case when no pressure is applied to the battery cell in the thickness direction. [Means for solving the problem]

[0008] One embodiment of the secondary battery according to the present invention comprises a winding body formed in a flat shape by winding together a positive electrode foil, a separator, and a negative electrode foil in an overlapping state; a case for housing the winding body; and an insulating film that encloses the winding body in a bag-like shape and insulates the winding body from the case, wherein the insulating film has a spacer formed by folding the film along a current collector portion in the winding body where the positive electrode foil or the negative electrode foil is bundled, and the spacer is sandwiched in the gap between the current collector portion and the case.

[0009] One embodiment of a secondary battery cell film according to the present invention is a secondary battery having a winding body formed in a flat shape by winding a positive electrode foil, a separator, and a negative electrode foil multiple times in a superimposed state, and a case for housing the winding body, wherein the secondary battery cell film encloses the winding body in a bag-like manner and insulates the winding body from the case, and comprises an insulating portion that encloses the surface of the winding body other than the opening surface provided in the region of the winding body that faces the lid that seals the case, and an overlapping spacer in which the film is folded along a current collecting portion in the winding body to which the positive electrode foil or the negative electrode foil is bundled, wherein the spacer is sandwiched in the gap between the current collecting portion and the case when the winding body is housed in the case. [Effects of the Invention]

[0010] According to the secondary battery and secondary battery cell film of the present invention, displacement of the wound body within the case can be prevented when no pressure is applied from the thickness direction of the battery cell. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the battery stack according to Embodiment 1. [Figure 2] This is a schematic diagram of a secondary battery cell according to Embodiment 1. [Figure 3] This is a cross-sectional view of a secondary battery cell, seen from the side, illustrating the structure of the insulating film of the secondary battery cell according to Embodiment 1. [Figure 4] This is a cross-sectional view of a secondary battery cell, seen from above, illustrating the structure of the insulating film of the secondary battery cell according to Embodiment 1. [Figure 5] This diagram illustrates the positional relationship between the cell spacer and the wound body of a secondary battery cell according to Embodiment 1. [Figure 6] This is a developed view of the insulating film according to Embodiment 1. [Figure 7] This diagram illustrates the process of winding an insulating film onto a secondary battery cell according to Embodiment 1. [Figure 8]It is a cross-sectional view of a secondary battery cell for explaining a first example of the structure of an insulating film of the secondary battery cell according to Embodiment 2, as seen from above. [Figure 9] It is a developed view of an insulating film applied to the secondary battery cell shown in FIG. 8. [Figure 10] It is a cross-sectional view of a secondary battery cell for explaining a second example of the structure of an insulating film of the secondary battery cell according to Embodiment 2, as seen from above. [Figure 11] It is a developed view of an insulating film applied to the secondary battery cell shown in FIG. 10. [Figure 12] It is a developed view of an insulating film according to Embodiment 3.

MODE FOR CARRYING OUT THE INVENTION

[0012] For the sake of clarity of explanation, the following description and drawings are appropriately omitted and simplified. Also, in each drawing, the same reference numerals are assigned to the same elements, and redundant explanations are omitted as necessary.

[0013] Embodiment 1 First, the usage form of the secondary battery cell 1 according to Embodiment 1 will be described. The secondary battery cell 1 according to Embodiment 1 is suitable for a battery that constitutes a battery pack in which a plurality of battery cells are combined. At this time, the battery pack is configured as a battery stack in which a plurality of secondary battery cells 1 are stacked. Therefore, FIG. 1 shows a schematic view of the battery stack according to Embodiment 1.

[0014] As shown in FIG. 1, the battery stack includes a first electrode component that is a positive electrode and a second electrode component that is a negative electrode, and has a plurality of secondary battery cells 1 that are stacked. Also, the secondary battery cells 1 are stacked with a cell spacer 2 interposed therebetween. In FIG. 1, the stacking direction of the secondary battery cells 1 is clearly shown. And in the following description, the length in the stacking direction of the secondary battery cell 1 is referred to as the secondary battery cell 1 thickness.

[0015] The secondary battery cell 1 has a bus bar 3 that connects the first electrode component and the second electrode component of adjacent secondary battery cells 1. More specifically, in the secondary battery cell 1 according to Embodiment 1, the bus bar 3 is joined to the electrode component by laser welding.

[0016] Here, in the battery stack, by applying a pressing force from the front and back in the stacking direction, each of the secondary battery cells 1 is constrained in a state where pressure is applied. However, the secondary battery cell 1 described below can be preferably used in a battery stack that is used in an unconstrained state where such a pressing force is not applied. Hereinafter, the secondary battery cell 1 will be described in more detail.

[0017] FIG. 2 shows a schematic diagram of the secondary battery cell 1 according to Embodiment 1. In the following description, the length of the secondary battery cell 1 in the stacking direction of the secondary battery cell 1 is defined as the thickness (Y direction in FIG. 2), the length of the long side of the case 10 in the direction orthogonal to the stacking direction of the secondary battery cell 1 is defined as the width of the secondary battery cell 1 (X direction in FIG. 2), and the length of the secondary battery cell 1 in the direction orthogonal to the stacking direction of the secondary battery cell 1 and from the bottom surface facing the lid 13 toward the lid 13 is defined as the height of the secondary battery cell 1 (Z direction in FIG. 2).

[0018] As shown in FIG. 2, the secondary battery cell 1 according to Embodiment 1 houses the winding body 12 in a secondary battery cell inner film (hereinafter referred to as the insulating film 11) formed in a bag shape, and the winding body 12 is housed in the case 10. Further, the secondary battery cell 1 closes the opening of the case 10 with the lid 13. In the secondary battery cell 1, the electrolyte is injected into the case 10 from the injection port 14 in a state where the lid 13 is attached to the case 10. After the injection, the injection port 14 is sealed with the cap 15.

[0019] In the example shown in Figure 2, a positive electrode current collector 21 and a negative electrode current collector 31 are provided on the left and right sides of the wound body 12. The positive electrode current collector 21 is, for example, the positive electrode of the secondary battery cell 1 and is a metal foil mainly composed of aluminum. The negative electrode current collector 31 is, for example, the negative electrode of the secondary battery cell 1 and is a metal foil mainly composed of copper. A positive electrode current collector component 22, which is a metal part mainly composed of aluminum, is joined to the positive electrode current collector 21. A negative electrode current collector component 32, which is a metal part mainly composed of copper, is joined to the negative electrode current collector 31.

[0020] The positive electrode current collector 22 is joined to the first electrode component 25, which is located on the outside of the case of the secondary battery cell 1. In the example shown in Figure 2, the projection on the first electrode component 25 is passed through the pole post through hole 17 provided in the lid 13, thereby joining the first electrode component 25 and the positive electrode current collector 22. The positive electrode current collector 22 and the first electrode component 25 are joined by crimping the projection on the first electrode component 25. At this time, a first internal insulator 23 is sandwiched between the positive electrode current collector 22 and the lid 13. A first external insulator 24 is sandwiched between the first electrode component 25 and the lid 13. The first internal insulator 23 and the first external insulator 24 seal the pole post through hole 17. The first internal insulator 23 and the first external insulator 24 are made of resin. The first internal insulator 23 insulates the positive electrode current collector component 22 from the cover 13, and the first external insulator 24 insulates the first electrode component 25 from the cover 13.

[0021] Figure 2 shows the positive electrode current collector component 22, the first internal insulator 23, the first external insulator 24, and the first electrode component 25 on the positive electrode side in their disassembled state before assembly. On the other hand, Figure 2 shows the negative electrode current collector component 32, the second internal insulator 33 (not shown in Figure 2), the second external insulator 34, and the second electrode component 35 on the negative electrode side in their assembled state.

[0022] In other words, the negative electrode current collector 32 is joined to the second electrode component 35, which is provided on the outside of the case of the secondary battery cell 1. The negative electrode current collector 32 and the second electrode component 35 are joined by crimping the protrusions of the second electrode component 35. At this time, a second internal insulator 33 (not shown in Figure 2) is sandwiched between the negative electrode current collector 32 and the lid 13. Also, a second external insulator 34 is sandwiched between the second electrode component 35 and the lid 13. The second internal insulator 33 and the second external insulator 34 seal the portion of the electrode post through hole (not shown in Figure 2) provided on the negative electrode side. The second internal insulator 33 and the second external insulator 34 are made of resin. The second internal insulator 33 insulates the negative electrode current collector component 32 from the cover 13, and the second external insulator 34 insulates the second electrode component 35 from the cover 13.

[0023] Here, the secondary battery cell 1 according to Embodiment 1 has one of its distinctive features in the configuration of the insulating film 11. Therefore, Figure 3 shows a cross-sectional view of the secondary battery cell as seen from the side, illustrating the structure of the insulating film of the secondary battery cell 1 according to Embodiment 1. The cross-sectional view in Figure 3 is a cross-section of the vicinity of the positive electrode side current collector 21 when the secondary battery cell 1 is viewed from the positive electrode side current collector 21 side of the winding body 12.

[0024] First, the insulating film 11 is made of an insulating resin, and it is preferable to use materials such as polyethylene or polypropylene in order to achieve the insulation properties, resistance to electrolyte, and thickness required by the characteristics of secondary batteries.

[0025] As shown in Figure 3, the secondary battery cell 1 is housed in a case 10 with the wound body 12 wrapped in an insulating film 11, and the case 10 is sealed inside the case 10 by placing a lid 13 over it. The insulating film 11 is assembled into a bag shape that encloses the wound body 12, but the part facing the lid 13 has an open shape.

[0026] Furthermore, the winding body 12 is formed by winding the positive electrode foil, separator, and negative electrode foil in an overlapping state, and then flattening it into a flattened shape. Therefore, the winding body 12 has flat sections where each sheet is flat and curved sections where the sheets are curved. The flat sections have surfaces that face the front and rear surfaces of the case 10. The curved sections have curved surfaces that face the bottom surface of the case 10 and the lid 13.

[0027] The positive electrode current collector portion 21 of the wound body 12 has a shape that is flattened in the thickness direction. In this case, the thickness increases near the curved portion because it has a curved surface, while the thickness decreases near the center in the height direction of the flat portion. The positive electrode current collector component 22 is then joined to the flattened portion where the thickness is reduced. The positive electrode current collector component 22 has a shape that avoids the thicker positive electrode current collector portion 21, and its end contacts the lid 13 via the first internal insulator 23. The positive electrode current collector portion 21 is joined to the first electrode component 25 provided on the outside of the lid 13, but the location of this joining is not shown.

[0028] In the secondary battery cell 1 according to Embodiment 1, the insulating film 11 is folded along the positive electrode current collector 21 and the negative electrode current collector 31 in the winding body 12 to form cell spacers 41 and 42, and the cell spacers 41 and 42 are sandwiched in the gap between the positive electrode current collector 21 and the case 10. More specifically, in the secondary battery cell 1, the cell spacer 41 is provided in the first gap between the positive electrode current collector 21 and the front surface of the case 10. In the first gap, the cell spacer 41 is provided between the positive electrode current collector component 22, which is formed to avoid the thicker part of the positive electrode current collector 21, and the front surface of the case 10. In addition, in the secondary battery cell 1, the cell spacer 42 is provided in the second gap between the negative electrode current collector 31 and the rear surface of the case 10.

[0029] Although Figure 3 only shows the structure on the positive electrode side current collector 21 side, the cell spacers 41 and 42 are provided in the same way on the negative electrode side current collector 31 side as well. From another perspective, the secondary battery cell 1 has a structure in which the positive electrode side current collector 21 and the positive electrode side current collector component 22 are sandwiched between the cell spacers 41 and 42.

[0030] Furthermore, the cell spacers 41 and 42 will be explained using cross-sectional views from a different angle. Figure 4 shows a cross-sectional view of a secondary battery cell 1 viewed from above, illustrating the structure of the insulating film 11 of the secondary battery cell 1 according to Embodiment 1. The cross-sectional view in Figure 4 shows the thicker portion of the positive electrode side current collector 21 and the negative electrode side current collector 31 of the wound body 12, on the side closer to the curve of the wound body 12.

[0031] As shown in Figure 4, the insulating film 11 wraps around the wound body 12, which includes the positive electrode current collector 21 and the negative electrode current collector 31, on all four sides. In this case, in the secondary battery cell 1, an internal cell spacer 41 is provided in the first gap between the positive electrode current collector 21 and the front surface of the case 10. More specifically, in the first gap, the internal cell spacer 41 is provided between the positive electrode current collector component 22, which is formed to avoid the thicker portion of the positive electrode current collector 21, and the front surface of the case 10. In addition, in the secondary battery cell 1, an internal cell spacer 42 is provided in the second gap between the negative electrode current collector 31 and the rear surface of the case 10. The internal cell spacers 41 and 42 are formed by folding a part of the insulating film 11.

[0032] Here, the relationship between the positions of the cell spacers 41 and 42 and the structure of the winding body 12 will be explained using another diagram. Therefore, Figure 5 shows a diagram illustrating the positional relationship between the cell spacers 41 and 42 and the winding body of the secondary battery cell 1 according to Embodiment 1. As shown in Figure 5, the cell spacers 41 and 42 are provided along the positive electrode side current collector 21 and the negative electrode side current collector 31 in the winding body 12.

[0033] In the secondary battery cell 1, the positive electrode current collector 21 and the negative electrode current collector 31 are constructed in a way that crushes the metal foil, reducing the restraining force in these areas. Therefore, an internal cell spacer 41 is provided between the front surface of the case 10 and the current collector, and an internal cell spacer 42 is provided between the rear surface of the case 10 and the current collector, thereby suppressing the amount of displacement between the current collector and the case. This prevents the displacement of the winding body 12 due to vibrations in the front-to-back direction (for example, the thickness direction of the cell) in the secondary battery cell 1, reducing the risk of tearing of the metal foil constituting the current collector. In particular, when the secondary battery cell 1 is used in an unrestrained state, there is no pressure applied to keep the case 10 and the winding body 12 in close contact, and there is concern that the amount of displacement of the winding body 12 within the case 10 will increase. Therefore, the effect of providing internal cell spacers 41 and 42 is significant in secondary battery cells 1 used in an unrestrained state.

[0034] In this embodiment, the insulating film 11 is formed by folding a sheet into a bag shape, and various forms can be considered for the unfolded view of the sheet that forms this bag shape. Therefore, Figure 6 shows the unfolded view of the insulating film according to embodiment 1.

[0035] As shown in Figure 6, the insulating film 11 has a rear surface that contacts one of the flat parts of the winding body 12, a front surface that contacts the other of the flat parts, two side surfaces that wrap around the two sides of the winding body 12, a bottom surface that wraps around the winding body 12 on the side facing the lid that seals the case and is located on the bottom surface of the case, and folded portions 51 and 52 that become cell spacers 41 and 42. In another view, the insulating film 11 has an insulating portion that wraps around the surface of the winding body 12 other than the opening surface provided in the region facing the lid that seals the case 10, and folded portions 51 and 52 that become cell spacers in which the film is folded along the positive electrode current collector 21 and the negative electrode current collector 31 on the winding body 12. As described above, the cell spacers 41 and 42 are sandwiched in the gap between the positive electrode current collector 21 and the negative electrode current collector 31 and the case 10 when the wound body 12 is housed in the case 10. Here, the insulating portion includes two sides that enclose two sides of the wound body 12, and a bottom surface that encloses the wound body 12 on the case bottom side, which is located opposite the lid that seals the case.

[0036] In the example shown in Figure 6, the insulating film 11 has a bottom portion below the rear surface. Additionally, a folding section 52, side sections, cell spacers 41, and a front section are provided, continuous with the rear surface and moving away from it in the left-right direction. In the example shown in Figure 6, the front section is divided into two parts and positioned at the furthest point from the rear surface. This shape allows all parts to be arranged continuously on a single sheet. Folds are provided in the folding sections 51, 52 and the side sections to facilitate the winding process of the insulating film 11, which will be described later. In Figure 6, mountain folds are shown with solid lines, and valley folds are shown with dashed lines. These folds increase or decrease depending on the number of folds of the folding sections 51, 52 and the back surface.

[0037] Next, Figure 7 shows a diagram illustrating the winding process of the insulating film 11 of the secondary battery cell 1 according to Embodiment 1. In the winding process shown in Figure 7, first, as step S0, the insulating film 11 is prepared as a sheet in an unfolded state as described in Figure 6. Next, as step S1, the cell internal spacers 41 and 42 are prepared by folding the folded portions 51 and 52 and the back surface of the insulating film 11. At this time, the sheet that makes up the back surface is also folded in half, but this is to facilitate the folding of the cell internal spacers 41 and 42, and in some cases it may not be necessary to fold it in half.

[0038] Next, in step S2, the back sheet of the part folded in step S1 is opened and the cell spacer 42 is moved to a position where it does not overlap with the cell spacer 41. In the unfolded view of step S2, the dashed lines on the side portion are the valley fold lines made on the side portion shown in Figure 6. Subsequently, in step S3, the winding body 12 is placed on the insulating film 11 so that it overlaps the rear surface and the cell spacer 42. Then, in step S4, the bottom surface, sides, and front surface, which were unfolded in the state of step S3, are folded to wrap the winding body 12 with the insulating film 11. Also in step S4, the positive electrode side current collector 21 and the negative electrode side current collector 31 of the winding body 12 are sandwiched between the cell spacer 41 and the cell spacer 42. Also in step S4, the front sheet, which is provided in sections, is connected with tape.

[0039] As described above, by preparing the insulating film 11 in the unfolded form shown in Figure 6, the winding process can be made easier.

[0040] As described above, in the secondary battery cell 1 having the insulating film 11 according to Embodiment 1, the cell spacers 41 and 42 are sandwiched in the gap between the positive electrode current collector 21 and the negative electrode current collector 31 and the case 10, thereby increasing the restraining force on the wound body 12 within the case 10. As a result, the secondary battery cell 1 according to Embodiment 1 can suppress the amount of displacement of the wound body 12 within the case 10 in response to vibrations in the thickness direction of the secondary battery cell 1, thereby improving the reliability of the wound body 12.

[0041] Suppressing the displacement of the wound body 12 in response to vibrations in the thickness direction of the secondary battery cell 1 is extremely useful for improving the reliability of the battery stack when the battery stack constructed using the secondary battery cell 1 is used in an unconstrained state.

[0042] Embodiment 2 Embodiment 2 describes two other forms of the secondary battery cell 1 according to Embodiment 1. Note that the components described in Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and their descriptions are omitted.

[0043] First, Figure 8 shows a cross-sectional view of a secondary battery cell viewed from above, illustrating a first example of the structure of the insulating film 11a of a secondary battery cell according to Embodiment 2. As shown in Figure 8, the secondary battery cell according to the first example of Embodiment 2 omits the cell spacer 42 and has a cell spacer 41. In other words, in the first example of Embodiment 2, the secondary battery cell has a cell spacer 41 only on the front side, with the side where the positive electrode foil is bundled being the first current collection unit side (for example, the positive electrode side current collection unit 21 side) and the side where the negative electrode foil is bundled being the second current collection unit side (for example, the positive electrode side current collection unit 21 side).

[0044] Here, we show the unfolded view of the insulating film 11a applied to the secondary battery cell shown in Figure 9. As shown in Figure 9, the insulating film 11a is the same as the unfolded view of the insulating film 11 shown in Figure 6, but with the folded portion 52 removed. Also, the insulating film 11a does not have folds on the sides. This is because the insulating film 11a does not require the sides to be folded during the winding process.

[0045] Furthermore, Figure 10 shows a cross-sectional view of a secondary battery cell viewed from above, illustrating a second example of the structure of the insulating film 11b of the secondary battery cell according to Embodiment 2. As shown in Figure 10, the secondary battery cell according to the second example of Embodiment 2 omits the cell spacer 41 and has a cell spacer 42. In other words, in the second example of Embodiment 2, the secondary battery cell has a cell spacer 42 only on the back side, with the side where the positive electrode foil is bundled being the first current collector side (for example, the positive electrode side current collector 21 side) and the side where the negative electrode foil is bundled being the second current collector side (for example, the positive electrode side current collector 21 side).

[0046] Here, we show the unfolded view of the insulating film 11b applied to the secondary battery cell shown in Figure 11. As shown in Figure 11, the insulating film 11b is the same as the unfolded view of the insulating film 11 shown in Figure 6, but with the folded portion 51 removed. Also, the insulating film 11b does not have folds on the sides. This is because the insulating film 11b does not require the sides to be folded during the winding process.

[0047] In the secondary battery cell according to Embodiment 2, an internal cell spacer is provided on only one of the front or rear sides. Even if an internal cell spacer is provided on only one of the front or rear sides in this way, the restraining force on the positive electrode current collector 21 and the negative electrode current collector 31 is increased, thus improving reliability against vibration in the thickness direction.

[0048] Furthermore, it is also possible to provide cell spacers at diagonal positions on the positive electrode current collector 21 side and the negative electrode current collector 31 side.

[0049] Embodiment 3 Embodiment 3 describes another example of the unfolded diagram of the insulating film 11. There are various possible unfolded diagrams for the sheets that make up the insulating film 11, but only one will be described here. Therefore, Figure 12 shows the unfolded diagram of the insulating film according to Embodiment 3.

[0050] In the example shown in Figure 12, the rear, bottom, and front surfaces are arranged continuously in the vertical direction of the drawing, with side surfaces positioned on the left and right of the bottom surface. Folding sections 51 are positioned at the upper part of the side surfaces, corresponding to the left and right positions of the rear surface, and folding sections 52 are positioned at the lower part of the side surfaces, corresponding to the left and right positions of the front surface. Even with a sheet arranged in this way, an insulating film 11 can be constructed from a single sheet.

[0051] Although not explained with diagrams, the insulating film 11 can also be constructed by separating each part and using multiple sheets.

[0052] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. [Explanation of Symbols]

[0053] 1 secondary battery cell 2-cell spacer 3 bus bars 10 cases 11. Insulating film 12 Wound body 13 Lid 14 Injection port 15 caps 16 Safety valve 17 Through-holes for pole columns 21 Positive electrode side current collector 22 Positive electrode current collector component 23 First internal insulator 24. First external insulator 25 First electrode component 31 Negative electrode current collector 32 Negative electrode current collector component 33. Second internal insulator 34. Second external insulator 35. Second electrode component 41, 42 Cell internal spacers 51, 52 Folding section

Claims

1. A winding body formed by winding together a positive electrode foil, a separator, and a negative electrode foil in an overlapping state, and forming a flattened shape, A case for housing the aforementioned coiled body, The device comprises an insulating film that encloses the winding body in a bag-like shape and insulates the winding body from the case, The aforementioned insulating film is A secondary battery in which a cell spacer is formed in the wound body by folding a film along a current collector to which the positive electrode foil or the negative electrode foil is bundled, and the cell spacer is sandwiched in the gap between the current collector and the case.

2. The secondary battery according to claim 1, wherein the insulating film has a rear surface in contact with one of the flat portions of the winding body, a front surface in contact with the other of the flat portions, two side surfaces that enclose the two sides of the winding body, a bottom surface that encloses the winding body on the case bottom side facing the lid that seals the case, and a folded portion that serves as a spacer inside the cell.

3. The secondary battery according to claim 2, wherein the cell spacer is provided in correspondence to at least one of a first gap formed on the front side of the gap formed between the current collector and the case, and a second gap formed on the rear side of the gap formed between the current collector and the case.

4. The secondary battery according to claim 2, wherein, when the side on which the positive electrode foils are bundled is designated as the first current collection unit side and the side on which the negative electrode foils are bundled is designated as the second current collection unit side, the cell spacer is provided on the same side on both the first current collection unit side and the second current collection unit side, and on either the rear surface or the front surface.

5. A secondary battery having a winding body formed into a flat shape by winding a positive electrode foil, a separator, and a negative electrode foil multiple times in an overlapping state, and a case for housing the winding body, wherein a secondary battery cell internal film encloses the winding body in a bag-like manner and insulates the winding body from the case, An insulating portion that encloses the surface of the winding body other than the opening surface provided in the region facing the lid that seals the case, The winding body includes an internal cell spacer in which a film is folded along a current collector where the positive or negative electrode foil is bundled, The cell spacer is a secondary battery cell film that is sandwiched in the gap between the current collector and the case when the wound body is housed in the case.

6. The secondary battery cell film according to claim 5, having a rear surface in contact with one of the flat portions of the winding body, a front surface in contact with the other of the flat portions, two side surfaces enclosing the two sides of the winding body, a bottom surface enclosing the winding body on the case bottom side facing the lid that seals the case, and a folded portion that serves as a cell spacer.

7. The secondary battery cell film according to claim 6, wherein, when the side on which the positive electrode foils are bundled is designated as the first current collection unit side and the side on which the negative electrode foils are bundled is designated as the second current collection unit side, the folded portion is provided on both the first current collection unit side and the second current collection unit side at a position corresponding to either the rear surface or the front surface.

8. The secondary battery cell film according to claim 6, wherein the secondary battery cell film is formed as a single sheet.

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