Cylindrical Cells and Battery Modules

Abstract

To provide a cylindrical battery capable of reducing a step in a winding direction of a winding electrode group.SOLUTION: A cylindrical battery comprises: a shaft center member 11; a winding electrode group 12 in which an electrode lamination body in which a positive electrode and a negative electrode are laminated via an electrolyte is wound around the shaft center member 11; a double-sided tape D that fixes an end part on the side not contacted to the shaft center member 11 in a winding direction of the winding electrode group 12; an outer casing member 15 that winds the winding electrode group 12 and the double-sided tape D. In the double-sided tape D, one end part in a winding direction is overlapped with the winding electrode group 12, and the other end part in the winding direction is overlapped with the outer casing member 15.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a cylindrical battery and a battery module. [Background technology]

[0002] In recent years, research and development into secondary batteries that contribute to energy efficiency has been conducted to ensure that many people have access to affordable, reliable, sustainable and advanced energy.

[0003] Patent Document 1 describes a nonaqueous electrolyte secondary battery having a cylindrical battery outer can and a wound electrode assembly in which a positive electrode plate having a positive electrode core coated on both sides with a positive electrode active material mixture and a negative electrode plate having a negative electrode core coated on both sides with a separator sandwiched between them and insulated from each other, and the wound electrode assembly is housed in the battery outer can. Here, a separator is disposed on the outermost periphery of the wound electrode assembly, and the separator is fixed to the outermost periphery of the wound electrode assembly with a winding tape. Furthermore, a negative electrode core without a negative electrode active material mixture layer is disposed on the outermost periphery of the negative electrode plate, and a negative electrode tab is connected to the outermost negative electrode core. Furthermore, the winding tape does not overlap with the winding end ends of the positive electrode plate and the negative electrode core. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-212086 Summary of the Invention [Problem to be solved by the invention]

[0005] In all-solid-state secondary batteries, in order to reduce the interfacial resistance between the solid electrolyte layer and the electrodes, an electrode stack in which a positive electrode and a negative electrode are stacked with a solid electrolyte layer interposed therebetween is pressed when being wound to produce a wound electrode group. In order to press the electrode stack uniformly, it is desirable to reduce the step in the winding direction of the wound electrode group.

[0006] An object of the present invention is to provide a cylindrical battery capable of reducing the step in the winding direction of a wound electrode group. [Means for solving the problem]

[0007] One aspect of the present invention is a cylindrical battery comprising: an axial core; a wound electrode group in which an electrode stack, in which positive and negative electrodes are stacked with an electrolyte interposed therebetween, is wound around the axial core; a fixing member that fixes an end of the wound electrode group on the side that is not in contact with the axial core in the winding direction; and an exterior member that winds the wound electrode group and the fixing member, wherein one end of the fixing member in the winding direction overlaps with the wound electrode group and the other end of the fixing member in the winding direction overlaps with the exterior member.

[0008] The fixing member may be an insulator, and the length of the fixing member in the axial direction of the shaft member may be greater than the length of the wound electrode group in the axial direction of the shaft member.

[0009] The fixing member may be a double-sided tape, one surface of which fixes the wound electrode group and the other surface of which fixes the exterior member.

[0010] The fixing member may be formed with a slope in a region between the wound electrode group and the exterior member in the winding direction, such that the thickness on the wound electrode group side is greater than the thickness on the exterior member side.

[0011] The thickness of the exterior member may be smaller than the thickness of the electrode stack.

[0012] The thickness of the exterior member may be greater than the thickness of the electrode stack minus the thickness of the positive electrode or the negative electrode.

[0013] The electrode stack may be formed by stacking the positive electrode and the negative electrode with a solid electrolyte layer interposed therebetween.

[0014] In another aspect of the present invention, a battery module includes a plurality of the above-described cylindrical batteries. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a cylindrical battery capable of reducing the step in the winding direction of the wound electrode group. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a partially cutaway perspective cross-sectional view showing an example of a battery module according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing the cylindrical battery of FIG. [Figure 3] FIG. 2 is a cross-sectional view showing the cylindrical battery of FIG. [Figure 4] 2 is a side view showing the cylindrical battery of FIG. 1 in a state before the exterior member is wound. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] Fig. 1 shows an example of a battery module of this embodiment. Fig. 2 and Fig. 3 show the cylindrical battery of Fig. 1. Fig. 3(b) is a partially enlarged view of the area surrounded by the dashed line in Fig. 3(a).

[0019] The battery module 100 includes a plurality of cylindrical batteries 10. Each cylindrical battery 10 includes an axial core member 11, a wound electrode group 12 formed by winding an electrode stack around the axial core member 11, the electrode stack including positive and negative electrodes stacked with an electrolyte interposed therebetween, a male screw portion 13A serving as a first fastening portion provided at one axial (upper) end of the axial core member 11, and a female screw portion 13B serving as a second fastening portion provided at the other axial (lower) end of the axial core member 11. In the battery module 100, adjacent cylindrical batteries 10 are connected via the male screw portion 13A and the female screw portion 13B.

[0020] In this case, the male screw portion 13A is molded integrally with the shaft core member 11. This improves the strength against the rotational torque when fastening the male screw portion 13A and the female screw portion 13B. The male screw portion 13A is electrically connected to one of the positive electrode and the negative electrode, and the female screw portion 13B is electrically connected to the other of the positive electrode and the negative electrode.

[0021] The first fastening portion may be a female thread portion, and the second fastening portion may be a male thread portion.

[0022] The axial member 11 has an insulating member 14 disposed between the first conductive member 11a and the second conductive member 11b in the axial direction, and the insulating member 14 is fastened to the first conductive member 11a and the second conductive member 11b. This compresses the insulating member 17, which will be described later, improving the sealing performance of the cylindrical battery 10. The first conductive member 11a has a female thread portion at its lower end in the axial direction. The insulating member 14 has a male thread portion at its upper end in the axial direction, and a female thread portion at its lower end in the axial direction. The second conductive member 11b has a male thread portion at its upper end in the axial direction.

[0023] The material forming the first conductive member 11a and the second conductive member 11b is not particularly limited, but examples thereof include metal, etc. The material forming the insulating member 14 is not particularly limited, but examples thereof include resins such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), and PFA.

[0024] The electrode laminate is in a sheet form, and each electrode has an electrode mixture layer formed on an electrode current collector. That is, the positive electrode has a positive electrode mixture layer formed on a positive electrode current collector, and the negative electrode has a negative electrode mixture layer formed on a negative electrode current collector. The electrolyte is not particularly limited, and may be contained in, for example, an electrolytic solution impregnated in a general resin porous membrane (separator), a gel electrolyte layer, a solid electrolyte layer, or the like.

[0025] The electrode laminate may have a plurality of positive electrodes and / or negative electrodes, as long as the positive electrodes and negative electrodes are stacked with the electrolyte interposed therebetween. Examples of the stack structure of an electrode laminate having a plurality of positive electrodes and / or negative electrodes include positive electrode / electrolyte / negative electrode / electrolyte / positive electrode. In this case, the electrode laminate can be produced by, for example, roll pressing.

[0026] The cylindrical battery 10 further includes a double-sided tape D as a fixing member for fixing the end of the wound electrode group 12 on the side not in contact with the axial center member 11 in the winding direction, and an exterior member 15 around which the wound electrode group 12 and the double-sided tape D are wound. One side of the double-sided tape D fixes the wound electrode group 12, and the other side fixes the exterior member 15. One end of the double-sided tape D in the winding direction of the wound electrode group 12 overlaps the wound electrode group 12, and the other end of the double-sided tape D in the winding direction of the wound electrode group 12 overlaps the exterior member 15 (see FIG. 4). This reduces the step in the winding direction of the wound electrode group 12 of the cylindrical battery 10. Note that FIG. 4 shows the cylindrical battery 10 in a state before the exterior member 15 is wound, and for convenience of explanation, extensions 18A and 18B, which will be described later, are not shown. Furthermore, the length of double-sided tape D in the axial direction of axial member 11 is greater than the length of wound electrode group 12 in the axial direction of axial member 11. In this case, since double-sided tape D is an insulator, insulation between wound electrode group 12 and exterior member 15 is ensured.

[0027] The length of the double-sided tape D in the winding direction of the wound electrode group 12 is not particularly limited, but is, for example, at least three times the thickness of the electrode laminate to be fixed (the sum of the thicknesses of the positive electrode, electrolyte, and negative electrode) and not more than half the circumferential length of the wound electrode group 12, and is preferably at least 10% and not more than 30% of the circumferential length of the wound electrode group 12. The thickness of the double-sided tape D is also not particularly limited, but is, for example, at least 5 μm and not more than 10 μm.

[0028] The wound electrode group 12 wrapped with the exterior member 15 is obtained by winding the electrode stack and the exterior member 15 around the axial core member 11 while applying a predetermined tension. At this time, the electrode stack and the exterior member 15 may be wound while pressing from the outside of the axial core member 11. As a result, the double-sided tape D is compressed, and a slope (see the dashed line in FIG. 3(b)) is formed in the region between the wound electrode group 12 and the exterior member 15 in the winding direction of the wound electrode group 12, where the thickness of the wound electrode group 12 side is greater than the thickness of the exterior member 15 side. As a result, the step in the winding direction of the wound electrode group 12 of the cylindrical battery 10 is reduced. Here, the slope may be an inclined plane or an inclined curved surface.

[0029] The fixing member is not limited to the double-sided tape D, and may be, for example, an adhesive. Alternatively, a step may be provided in the fixing member, and the exterior member 15 may be wound around the step provided in the fixing member.

[0030] The exterior member 15 is in a sheet form. The material forming the exterior member 15 is not particularly limited as long as it has conductivity, and examples thereof include metals.

[0031] Because the thickness of the exterior member 15 is smaller than the thickness of the electrode stack, the gap between the wound electrode group 12 and the exterior member 15 is smaller, making it easier to hold the wound electrode group 12 in the exterior member 15. In addition, because the thickness of the exterior member 15 is greater than the thickness of the electrode stack minus the thickness of the positive electrode or negative electrode, steps in the winding direction of the wound electrode group 12 of the cylindrical battery 10 are smaller.

[0032] Here, the thickness of the exterior member 15 is not particularly limited, but is, for example, 100 μm or more and 300 μm or less. On the other hand, the thickness of the electrode laminate is not particularly limited, but is, for example, 110 μm or more and 310 μm or less. Furthermore, the thickness of the positive electrode is not particularly limited, but is, for example, 50 μm or more and 150 μm or less. Furthermore, the thickness of the negative electrode is not particularly limited, but is, for example, 60 μm or more and 160 μm or less.

[0033] Cylindrical battery 10 further includes a first lid member 16A located at one (upper) end in the axial direction and electrically connected to one of the positive and negative electrodes, and a second lid member 16B located at the other (lower) end in the axial direction and electrically connected to the other of the positive and negative electrodes. First lid member 16A and second lid member 16B each have an inclined region that is inclined approximately symmetrically with respect to axial member 11 and have a conical outer shape. A ring-shaped insulating member 17 is disposed between exterior member 15 and first lid member 16A. First lid member 16A is electrically connected to male thread portion 13A, and second lid member 16B is electrically connected to female thread portion 13B and exterior member 15.

[0034] There are no particular limitations on the angle of inclination of the inclined regions of first cover member 16A and second cover member 16B relative to shaft member 11. The angle of inclination of the inclined region of first cover member 16A relative to shaft member 11 is determined by the height of extension portion 18A adjacent to the side of shaft member 11 of wound electrode group 12 and the width determined by the number of turns of wound electrode group 12. Furthermore, the inclined region of first cover member 16A has a volume that can accommodate extension portion 18A.

[0035] The material that makes up first lid member 16A and second lid member 16B is not particularly limited as long as it is conductive, and examples include metal, etc. The materials that make up first lid member 16A and second lid member 16B may be the same or different.

[0036] Furthermore, the insulating member 17 is compressed by the fastening force between the male screw portion 13A provided at the upper end in the axial direction of the axial core member 11 and the female screw portion 13B provided at the lower end in the axial direction of the axial core member 11, and as a result, the exterior member 15 and the first cover member 16A are fixed and sealed together. Meanwhile, the contact portion of the second cover member 16B with the exterior member 15 is joined by laser welding, and they are sealed and integrated together.

[0037] The material constituting the insulating member 17 is not particularly limited, but examples thereof include resins such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), and PFA.

[0038] The positive electrode current collector has an extending portion 18A extending from one (upper) end in the axial direction of the wound electrode group 12, and the negative electrode current collector has an extending portion 18B extending from the other (lower) end in the axial direction of the wound electrode group 12. Here, extending portion 18A of the positive electrode current collector collects current to first cover member 16A, and extending portion 18B of the negative electrode current collector collects current to second cover member 16B.

[0039] In this case, the second lid member 16B, which is electrically connected to the extension portion 18B that collects current on the exterior member 15, has a larger inclination angle of the inclined region than the first lid member 16A, which is electrically connected to the extension portion 18A that collects current on the shaft center member 11. This makes it easier to connect adjacent cylindrical batteries 10 via the male thread portion 13A and the female thread portion 13B.

[0040] Hereinafter, a case will be described in which the cylindrical batteries constituting the battery module of this embodiment are all-solid-state lithium secondary batteries.

[0041] The positive electrode current collector is not particularly limited, but may be, for example, aluminum foil.

[0042] The positive electrode mixture layer contains a positive electrode active material, and may further contain a solid electrolyte, a conductive additive, a binder, and the like.

[0043] The positive electrode active material is not particularly limited as long as it can absorb and release lithium ions. For example, LiCoO2, Li(Ni 5 / 10 Co 2 / 10 Mn 3 / 10 )O 2、 Li(Ni) 6 / 10 Co 2 / 10 Mn 2 / 10 )O 2、 Li(Ni) 8 / 10 Co 1 / 10 Mn 1 / 10 )O 2、 Li(Ni) 0.8 Co 0.15 Al 0.05 )O 2、 Li(Ni) 1 / 6 Co 4 / 6 Mn 1 / 6 )O 2、 Li(Ni) 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2、 Examples include LiCoO4, LiMn2O4, LiNiO2, LiFePO4, lithium sulfide, and sulfur.

[0044] The solid electrolyte constituting the solid electrolyte layer is not particularly limited as long as it is a material capable of conducting lithium ions, and examples thereof include oxide-based electrolytes, sulfide-based electrolytes, and molecular crystalline electrolytes in which the electrolyte is dissociated into crystalline bodies made of organic substances.

[0045] The negative electrode mixture layer contains a negative electrode active material, and may further contain a solid electrolyte, a conductive additive, a binder, and the like.

[0046] The negative electrode active material is not particularly limited as long as it is capable of absorbing and releasing lithium ions, and examples thereof include metallic lithium, lithium alloys, metal oxides, metal sulfides, metal nitrides, Si, SiO, carbon materials, etc. Examples of carbon materials include artificial graphite, natural graphite, hard carbon, soft carbon, etc.

[0047] The negative electrode current collector is not particularly limited, but examples thereof include copper foil.

[0048] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments may be modified as appropriate within the scope of the spirit of the present invention. [Explanation of symbols]

[0049] 10 Cylindrical battery 11 Shaft core member 11a First conductive member 11b Second conductive member 12-wound electrode group 13A male thread 13B female thread 14, 17 Insulating member 15 Exterior materials 16A First cover member 16B Second cover member 18A, 18B extension part 100 Battery Module D. Double-sided tape

Claims

1. a shaft core member; a wound electrode group in which an electrode stack, in which a positive electrode and a negative electrode are stacked with an electrolyte interposed therebetween, is wound around the shaft member; a fixing member that fixes an end portion of the wound electrode group on a side that is not in contact with the shaft member in the winding direction; an exterior member around which the wound electrode group and the fixing member are wound, a cylindrical battery in which one end of the fixing member in the winding direction overlaps with an end of the wound electrode group on a side that is not in contact with the axial member in the winding direction, and the other end of the fixing member in the winding direction overlaps with an end of the exterior member on the fixing member side in the winding direction.

2. the fixing member is an insulator, The cylindrical battery according to claim 1 , wherein the length of the fixing member in the axial direction of the shaft member is greater than the length of the wound electrode group in the axial direction of the shaft member.

3. the fixing member is a double-sided tape, 3. The cylindrical battery according to claim 1, wherein one surface of the double-sided tape fixes the wound electrode group, and the other surface fixes the exterior member.

4. 4. The cylindrical battery according to claim 1, wherein the fixing member has a slope formed such that the thickness of the fixing member on the side of the wound electrode group is greater than the thickness of the fixing member on the side of the wound electrode group in the winding direction in a region between the wound electrode group and the exterior member.

5. The cylindrical battery according to claim 1 , wherein the thickness of the exterior member is smaller than the thickness of the electrode stack.

6. The cylindrical battery according to claim 5 , wherein the thickness of the exterior member is greater than the thickness of the electrode stack minus the thickness of the positive electrode or the negative electrode.

7. The cylindrical battery according to claim 1 , wherein the electrode stack is formed by stacking the positive electrode and the negative electrode with a solid electrolyte layer interposed therebetween.

8. A battery module comprising a plurality of cylindrical batteries according to claim 1 .

Images