Secondary battery

Abstract

To provide a secondary battery capable of effectively reducing melting, cleavage or the like of a battery case due to a high-temperature ejected object continuously generated from an electrode body with a simple structure at an abnormal time when a short circuit or the like occurs in the electrode body.SOLUTION: A secondary battery 10 includes an electrode body 2 in which a positive electrode body 21 in which a positive electrode active material layer 21K is applied to a positive electrode foil 21H and a negative electrode body 22 in which a negative electrode active material layer 22K is applied to a negative electrode foil 22H are laminated with a separator 23 interposed therebetween, a battery case 1 in which the electrode body is housed and sealed, and a shielding member 5 disposed between the electrode body and the battery case and configured to shield a jetting object jetting from the electrode body to the battery case side due to a short circuit or the like between the positive electrode body and the negative electrode body.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a secondary battery. [Background technology]

[0002] In recent years, there has been an increasing demand for larger secondary batteries and higher energy densities for use in electric vehicles and the like. In these larger, higher energy density secondary batteries, there is a possibility that large amounts of high-temperature ejecta and gas may be generated in the event of an abnormality such as a short circuit occurring within the electrode body. In this case, the high-temperature ejecta continuously ejected from the gap between the positive and negative electrode bodies may melt the wall of the battery case, potentially causing the battery case to split.

[0003] As a measure to avoid this, for example, Patent Document 1 discloses: (1) forming a battery case with a multi-layer structure including an outer layer made of a highly rigid material such as steel and an inner layer made of a plastic having gas-absorbing properties, and (2) packaging the electrode body with a laminate film having an aluminum foil as an intermediate layer and plastic films on both sides of the intermediate layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-191400 Summary of the Invention [Problem to be solved by the invention]

[0005] However, to form a battery case with a multi-layer structure made of different materials, one method is to draw a clad material plate made of different materials, but this method is not preferred because it is prone to cracking during molding. Another method involves forming the outer and inner case layers separately and then combining them with an adhesive, but this method is not preferred because it complicates the process and increases costs. Furthermore, a laminate film with an aluminum foil middle layer and plastic films on both sides is easily melted by high-temperature ejected material, and therefore cannot be expected to prevent the battery case from cracking (melting).

[0006] The disclosed technology has been made in consideration of such problems, and aims to provide a secondary battery with a simple structure that can effectively reduce the melting, cracking, etc. of the battery case caused by the continuous generation of high-temperature ejecta in the event of an abnormality such as a short circuit occurring within the electrode body. [Means for solving the problem]

[0007] (1) One aspect of the disclosed technology for solving the above problems is a secondary battery including: an electrode body in which a positive electrode body in which a positive electrode foil is coated with a positive electrode active material layer and a negative electrode body in which a negative electrode foil is coated with a negative electrode active material layer are stacked with a separator sandwiched therebetween; a battery case in which the electrode body is housed and sealed; and a shielding member disposed between the electrode body and the battery case and which shields ejected material ejected from the electrode body toward the battery case.

[0008] (2) In the secondary battery described in (1), it is preferable that the shielding member includes a shielding portion that faces an open edge portion of the electrode body where the edge portion of the positive electrode body and the edge portion of the negative electrode body are open in a direction perpendicular to the stacking direction of the electrode body, and a shielding support portion that supports the shielding portion while keeping it spaced apart from the inner wall surface of the battery case.

[0009] (3) In the secondary battery described in (1) or (2), the shielding member is preferably formed by coating a metal member having a melting point higher than the higher of the melting points of the positive electrode foil and the negative electrode foil with an insulating member, or by using an insulating inorganic material having a melting point higher than the higher of the melting points of the positive electrode foil and the negative electrode foil.

[0010] (4) In the secondary battery according to any one of (1) to (3), it is preferable that the shielding member is connected to or formed integrally with an insulating film that surrounds the electrode body. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of a secondary battery according to a first example of one aspect of the present embodiment. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] 2 is a cross-sectional view of FIG. 1 shown in FIG. [Figure 4] FIG. 2 is a schematic perspective view of a shielding member in the secondary battery shown in FIG. [Figure 5] 1. FIG. 5 is a cross-sectional view taken along the line BB in a first modified example of the secondary battery shown in FIG. [Figure 6] 1. FIG. 5 is a cross-sectional view taken along the line BB in a second modification of the secondary battery shown in FIG. [Figure 7] FIG. 10 is a schematic cross-sectional view of a secondary battery according to a second example of one aspect of the present embodiment. [Figure 8] This is the CC cross section shown in Figure 7. [Figure 9] FIG. 8 is a cross-sectional view taken along the line DD in FIG. [Figure 10] FIG. 8 is a schematic perspective view of a shielding member in the secondary battery shown in FIG. [Figure 11] FIG. 10 is a schematic cross-sectional view of a secondary battery according to a third example of one aspect of the present embodiment. [Figure 12] This is the E-E cross section shown in FIG. [Figure 13] FIG. 12 is a cross-sectional view of the FF shown in FIG. [Figure 14]FIG. 12 is a schematic perspective view of a shielding member in the secondary battery shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Description of Secondary Battery According to First Example> Next, the configuration of a secondary battery according to a first example of one aspect of an embodiment of the disclosed technology will be described in detail with reference to the drawings. Fig. 1 shows a schematic cross-sectional view of a secondary battery according to a first example of one aspect of this embodiment. Fig. 2 shows a cross-sectional view taken along line AA in Fig. 1. Fig. 3 shows a cross-sectional view taken along line BB in Fig. 1. Fig. 4 shows a schematic perspective view of a shielding member in the secondary battery shown in Fig. 1. The X direction indicates the longitudinal direction of the battery case, the Y direction indicates the vertical direction of the battery case, and the Z direction indicates the short-side direction (width direction) of the battery case (the same applies below).

[0013] As shown in FIGS. 1 to 4, the secondary battery 10 according to the first embodiment includes a battery case 1, an electrode assembly 2, a current collecting terminal 4, and a shielding member 5. The battery case 1 includes a rectangular opening 111 at its upper end, a bottomed, rectangular cylindrical case body 11 that is capable of receiving the electrode assembly 2 through the opening 111, and a long, flat lid 12 that seals the opening 111. The case body 11 includes a pair of long side walls 11a extending in the longitudinal direction (X direction), a pair of short side walls 11b extending in the lateral direction (Z direction), and a bottom wall 11c connected to the lower ends of the long side walls 11a and the short side walls 11b. The battery case 1 can be made of, for example, aluminum or an aluminum alloy.

[0014] Furthermore, insertion holes 121 for the current collector terminals 4 are formed at both ends of the lid 12 in the longitudinal direction (X direction), and the external terminals 41 of the current collector terminals 4 inserted into the insertion holes 121 are fixed via insulating resin members 3. The insulating resin members 3 may be made of, for example, polyphenylene sulfide (PPS) resin. The lid 12 also has an injection port 122 for injecting an electrolyte into the battery case 1, and a safety valve 123 that is formed to be able to open when the gas pressure inside the battery case 1 rises to or exceeds a predetermined value. The electrolyte injected through the injection port 122 is mainly impregnated into the electrode body 2. Note that the battery case 1 is not limited to the above-mentioned form as long as the interior of the battery case 1 is airtight.

[0015] The electrode body 2 is formed by stacking a positive electrode body 21, which is formed by coating a positive electrode foil 21H with a positive electrode active material layer 21K, and a negative electrode body 22, which is formed by coating a negative electrode foil 22H with a negative electrode active material layer 22K, with a separator 23 sandwiched between them. Here, the electrode body 2 is formed by stacking a strip-shaped positive electrode body 21 and a negative electrode body 22 with a strip-shaped separator 23 sandwiched between them and wound in a flat shape. An active material uncoated portion 211 of the positive electrode body 21 and an active material uncoated portion 221 of the negative electrode body 22 are formed at both ends in the longitudinal direction (X direction) of the electrode body 2. The active material uncoated portion 211 of the positive electrode body 21 is joined to an internal terminal 42 of the positive electrode current collector terminal 4A, and the active material uncoated portion 221 of the negative electrode body 22 is joined to an internal terminal 42 of the negative electrode current collector terminal 4B.

[0016] For example, in a lithium ion secondary battery, which is an example of the secondary battery 10, the positive electrode foil 21H of the positive electrode body 21 is made of, for example, aluminum foil, and the positive electrode active material layer 21K coated thereon contains, as an active material, for example, lithium transition metal oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3The negative electrode foil 22H of the negative electrode body 22 may be made of, for example, copper foil, and the negative electrode active material layer 22K coated thereon may be made of, for example, graphite, hard carbon, soft carbon, or the like. The separator 23 may be made of, for example, a porous sheet of polypropylene resin or polyethylene resin. The positive electrode current collector terminal 4A is made of, for example, aluminum, and the negative electrode current collector terminal 4B is made of, for example, copper.

[0017] Furthermore, the shielding member 5 is disposed between the electrode body 2 and the battery case 1, and is formed to shield ejected material SP having a temperature higher than the melting point of the battery case 1 that is ejected from the electrode body 2 toward the battery case 1 due to a short circuit TR between the positive electrode body 21 and the negative electrode body 22, etc. Therefore, when a foreign object enters the electrode body 2, causing a short circuit TR, etc., and high-temperature ejected material SP is continuously ejected toward the battery case 1 from the gap between the positive electrode body 21 and the negative electrode body 22, the shielding member 5 can prevent the ejected material SP from directly colliding with the battery case 1. As a result, the high-temperature ejected material SP can melt the wall surface of the battery case 1, reducing the risk of the battery case 1 cracking.

[0018] Here, the shielding member 5 includes a short-side-wall-side shielding portion 51 formed between the electrode assembly 2 and the short-side-wall portion 11b of the case body 11, a long-side-wall-side shielding portion 53 formed between the electrode assembly 2 and the long-side-wall portion 11a of the case body 11, and a bottom-wall-side shielding portion 54 formed between the electrode assembly 2 and the bottom-wall portion 11c of the case body 11. The shielding member 5 is formed into a bottomed rectangular tubular shape by integrally connecting the short-side-wall-side shielding portion 51, the long-side-wall-side shielding portion 53, and the bottom-wall-side shielding portion 54. The corners of the bottomed rectangular tubular shape of the shielding member 5 may be formed in an arc-shaped or chamfered shape. This is because the corners expand and can avoid cracking due to high-temperature, high-pressure gas generated due to a short circuit TR of the electrode assembly 2, etc.

[0019] Furthermore, it is preferable that a lid-side shielding portion 55 be provided extending from the upper end of the shielding portion 51 on the short side wall side to shield the insulating resin member 3 that secures the external terminals 41 to both ends of the lid 12 in the longitudinal direction (X direction). Here, the lid-side shielding portion 55 is formed in a range that protects the insulating resin member 3 from ejected material SP that scatters upward from the electrode assembly 2. The lid-side shielding portion 55 is formed with a notch 551 through which the internal terminal 42 of the current collecting terminal 4 is inserted. The upper end 531 of the shielding member 5 is open upward to allow the electrode assembly 2 to be inserted, and is formed to be able to communicate with the injection port 122 and safety valve 123 formed in the lid 12. This is to facilitate impregnation of the electrode assembly 2 with the electrolyte injected from the injection port 122 and to facilitate release of high-temperature, high-pressure gas from the safety valve 123.

[0020] In addition, it is preferable that the shielding member 5 includes a shielding portion 51 (here, this corresponds to the shielding portion 51 on the short side wall side) that faces the electrode body open edge portion 2T where the edge portion 21T of the positive electrode body 21 and the edge portion 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2, and a shielding support portion 52 that supports the shielding portion 51 while spacing it from the inner wall surface 1N of the battery case 1.

[0021] 3, ejected material SP generated when the positive electrode body 21 and the negative electrode body 22 are short-circuited is ejected in large quantities from the electrode body open edge 2T, where the edge 21T of the positive electrode body 21 and the edge 22T of the negative electrode body 22 are open, in a direction perpendicular to the stacking direction of the electrode body 2. Therefore, by having the shielding portion 51 on the short side wall face facing the electrode body open edge 2T, the ejected material SP can be more effectively shielded. In addition, since the shielding support portion 52 is provided, which supports the shielding portion 51 while separating it from the inner wall surface 1N of the battery case 1, an air layer KS is formed between the shielding portion 51 and the battery case 1, making it difficult for the heat of the ejected material SP to be transferred from the shielding portion 51 to the inner wall surface 1N of the battery case 1. Therefore, the heat of the ejected material SP can be more effectively blocked, further reducing melting and cracking of the battery case 1.

[0022] 1 and 4, the shielding support portions 52 are preferably formed at the widthwise (Z-direction) ends of the shielding portion 51 and at positions where the shielding portion 51 is divided into multiple sections in the up-down direction (Y-direction). Also, the shielding support portions 52 are preferably formed at the widthwise (Z-direction) ends of the shielding portion 54 and at positions where the shielding portion 54 is divided into multiple sections in the longitudinal direction (X-direction), as shown in FIGS. 1 and 2. The shielding portions 51 and 54 are less likely to deform due to the impact force of the ejected material SP, and the ejected material SR and its heat are less likely to penetrate into the gap between the shielding portions 51 and 54 and the inner wall surface 1N of the battery case 1. This improves the shielding performance of the shielding member 5.

[0023] As shown in FIGS. 2 and 3, the shielding member 5 is preferably formed by covering a metal member 5K having a melting point higher than the higher of the melting points of the positive electrode foil 21H and the negative electrode foil 22H with an insulating member 5Z. Since the ejected material SP is mainly generated by the melting and scattering of the positive electrode foil 21H or the negative electrode foil 22H, the metal member 5K having a melting point higher than the higher of the melting points of the positive electrode foil 21H and the negative electrode foil 22H is less likely to be melted by the ejected material SP. Therefore, even if the ejected material SP is continuously ejected for a long period of time, the shielding performance of the shielding member 5 can be maintained. It is also preferable that the end portion 5KT of the metal member 5K is covered with an insulating member 5Z. This is because the metal member 5K can be prevented from being corroded by the electrolyte or the like.

[0024] Specifically, when the positive electrode foil 21H is made of aluminum, for example, and the negative electrode foil 22H is made of copper, for example, the metal member 5K need not be particularly limited as long as it has a melting point higher than the melting point of copper (approximately 1085°C), since the melting point of aluminum is approximately 660°C and the melting point of copper is approximately 1085°C. For example, since the melting point of stainless steel is approximately 1400 to 1500°C, the metal member 5K may be formed of stainless steel foil (with a thickness of approximately 0.1 to 0.3 mm). The metal member 5K may also be nickel foil, which has a melting point of approximately 1455°C. The metal member 5K may be formed of a single foil, or may be formed of multiple foils with an air layer sandwiched between them. The insulating member 5Z may be formed of, for example, polypropylene resin or polyethylene resin. The shielding member 5 may be made of an insulating inorganic material 5M having a melting point higher than the higher of the melting points of the positive electrode foil 21H and the negative electrode foil 22H. The insulating inorganic material 5M may be, for example, alumina (melting point of about 2050°C) or zircon (melting point of about 1775°C).

[0025] 1 to 4, the shielding member 5 is formed into a bottomed rectangular tube shape by integrally connecting the shielding portion 51 on the short side wall side, the shielding portion 53 on the long side wall side, and the shielding portion 54 on the bottom wall side, and therefore it is preferable to form each of the shielding portions 51, 53, 54 by covering a metal member 5K having a melting point higher than the higher of the melting points of the positive electrode foil 21H and the negative electrode foil 22H with an insulating member 5Z. In this case, as shown in FIGS. 2 and 3, it is preferable to form the metal members 5K of the shielding portions 51, 53 on the short side wall side and the long side wall side into a rectangular ring-like shape, and form the metal member 5K of the shielding portion 54 on the bottom wall side into a hat-shaped shape, and then join the outer peripheral flange portions 5KS of both members together.

[0026] In the electrode assembly 2 wound flat as shown in FIG. 2, the shielding portion 51 on the short side wall side from which ejected material SP is likely to be ejected is formed by covering the metal member 5K with the insulating member 5Z, and the other shielding portions 53 and 54 surrounding the electrode assembly 2 are made of an insulating film 6 formed only from the insulating member 5Z, and the two may be connected or formed integrally. In this case, the weight of the shielding member 5 can be reduced. Also, misalignment between the electrode assembly 2 and the shielding member 5 can be prevented, and ejected material SP can be more reliably shielded. Furthermore, the shielding member 5 and the insulating film 6 can be stored together in the battery case 1, further simplifying the battery assembly process.

[0027] (Variations 1 and 2) The secondary battery 10 of the first embodiment described above may be modified as follows. Fig. 5 shows a cross-sectional view taken along line B-B of a first variation of the secondary battery shown in Fig. 1. Fig. 6 shows a cross-sectional view taken along line B-B of a second variation of the secondary battery shown in Fig. 1. Secondary batteries 10B and 10C of the first and second variations have simplified shielding member 5 of the secondary battery 10 of the first embodiment described above, and share the battery case 1, electrode assembly 2, and current collecting terminal 4. The simplified shielding members 5B and 5C will be mainly described here, and the common battery case 1, electrode assembly 2, and current collecting terminal 4 will be assigned the same reference numerals and will not be described in detail in principle.

[0028] 5, the shielding member 5B of the secondary battery 10B of the first modification includes a shielding portion 51 (corresponding to the shielding portion 51 on the short side wall side) that faces an electrode body open edge portion 2T where an end edge portion 21T of the positive electrode body 21 and an end edge portion 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2, and a shielding support portion 52 that supports the shielding portion 51 while spacing it from the inner wall surface 1N of the battery case 1. The shielding member 5B also includes a shortened shielding portion 53B on the long side wall side that is formed between the electrode body 2 and the long side wall portion 11a of the case body 11, and a shortened shielding portion 54B on the bottom wall side that is formed between the electrode body 2 and the bottom wall portion 11c of the case body 11, near the electrode body open edge portion 2T. As shown in FIG. 5, the shielding portion 51, the shielding support portion 52, and the shielding portion 53B are formed by covering a metal member 5K (5K1, 5K2) with an insulating member 5Z, and are formed to have an H-shaped cross section in a plan view.

[0029] In this case, even if ejected material SP generated by a short circuit TR between the positive electrode body 21 and the negative electrode body 22 or the like is ejected in large quantities from the electrode body open edge 2T where the edge 21T of the positive electrode body 21 and the edge 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2, the shielding portion 51 on the short side wall side facing the electrode body open edge 2T can prevent the ejected material SP from colliding with the short side wall 11b of the case body 11. In addition, the shielding support portion 52 uniformly separates the shielding portion 51 from the inner wall surface 1N of the battery case 1 by a predetermined distance, so that a uniform air layer KS is formed between the shielding portion 51 and the battery case 1, making it difficult for heat from the ejected material SP to be transferred from the shielding portion 51 to the inner wall surface 1N of the battery case 1.

[0030] Furthermore, the shielding member 5B includes a shortened shielding portion 53B on the long side wall side and a shortened shielding portion 54B on the bottom wall side, which can prevent the ejected material SP reflected from the shielding portion 51 on the short side wall side from scattering toward the long side wall portion 11a and the bottom wall portion 11c of the case body 11. Furthermore, by shortening the shielding portion 53B on the long side wall side and the shielding portion 54B on the bottom wall side in the longitudinal direction (X direction), the weight of the shielding member 5B can be significantly reduced. Therefore, the shielding member 5B can be simplified and made lighter while effectively blocking the heat of the ejected material SP and reducing the melting and cracking of the battery case 1.

[0031] 6, the shielding member 5C of the secondary battery 10C of the second modification includes a shielding portion 51 (corresponding to the shielding portion 51 on the short side wall side here) that faces the electrode body open edge portion 2T where the edge portion 21T of the positive electrode body 21 and the edge portion 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2, and a shielding support portion 52 that supports the shielding portion 51 while keeping it apart from the inner wall surface 1N of the battery case 1. As shown in FIG. 6, the shielding portion 51 and the shielding support portion 52 are formed by covering metal members 5K (5K1, 5K2) with insulating members 5Z and are connected to form a substantially U-shaped cross section.

[0032] In this case, even if ejected material SP generated by a short circuit TR between the positive electrode body 21 and the negative electrode body 22 or the like is ejected in large quantities from the electrode body open edge 2T where the edge 21T of the positive electrode body 21 and the edge 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2, the shielding portion 51 on the short side wall side facing the electrode body open edge 2T can prevent the ejected material SP from colliding with the short side wall portion 11b of the case body 11. In addition, the shielding support portion 52 separates the shielding portion 51 from the inner wall surface 1N of the battery case 1 by a predetermined distance, so that an air layer KS is formed between the shielding portion 51 and the battery case 1, making it difficult for heat from the ejected material SP to be transferred from the shielding portion 51 to the inner wall surface 1N of the battery case 1. In addition, by eliminating the shielding portion 53 on the long side wall side and the shielding portion 54B on the bottom wall side, the weight of the shielding member 5C can be further reduced. Therefore, the shielding member 5C can be simplified and made lighter, while effectively blocking the heat of the ejected material SP, thereby reducing the likelihood of the battery case 1 melting or splitting.

[0033] Furthermore, in the secondary batteries 10B and 10C of Modifications 1 and 2, it is also preferable that the shielding members 5B and 5C are connected to or integrally formed with the insulating film 6 that surrounds the electrode body 2. In this case, misalignment between the electrode body 2 and the shielding members 5B and 5C can be prevented, and the ejected material SP can be more reliably shielded. Furthermore, the shielding members 5B and 5C and the electrode body 2 can be housed together in the battery case 1, further simplifying the battery assembly process.

[0034] <Description of Secondary Battery According to Second Example> Next, the configuration of a secondary battery according to a second example of one aspect of the embodiment of the disclosed technology will be described in detail with reference to the drawings. Fig. 7 shows a schematic cross-sectional view of a secondary battery according to a second example of one aspect of the present embodiment. Fig. 8 shows a cross-section taken along CC in Fig. 7. Fig. 9 shows a cross-section taken along DD in Fig. 7. Fig. 10 shows a schematic perspective view of a sputter shielding member in the secondary battery shown in Fig. 7.

[0035] As shown in FIGS. 7 to 10, the secondary battery 10D according to the second embodiment includes a battery case 1, an electrode assembly 2D, a current collecting terminal 4D, and a shielding member 5D. Components common to the secondary battery 10 according to the first embodiment are designated by common reference numerals, and descriptions thereof will generally be omitted. The battery case 1 includes a case body 11 in the shape of a rectangular cylinder with a bottom, and a flat lid 12. Insertion holes 121 for the current collecting terminal 4D are formed at both ends of the lid 12 in the longitudinal direction (X direction), and external terminals 41D of the current collecting terminal 4D inserted into the insertion holes 121 are fixed via an insulating resin member 3D. The insulating resin member 3D can be made of, for example, polyphenylene sulfide (PPS) resin.

[0036] The electrode body 2D is formed by stacking rectangular positive electrode bodies 21 and negative electrode bodies 22 in a rectangular parallelepiped shape with a rectangular separator 23 sandwiched therebetween. A tab portion 24 of the positive electrode foil 21H and a tab portion 24 of the negative electrode foil 22H are formed at both longitudinal end portions (X direction) of the upper end portion of the electrode body 2. The tab portion 24 of the positive electrode foil 21H is joined to an internal terminal 42D of the positive electrode current collector terminal 4DA, and the tab portion 24 of the negative electrode foil 22H is joined to an internal terminal 42D of the negative electrode current collector terminal 4DB.

[0037] The shielding member 5D includes a first shielding member 5D1 disposed between the electrode body 2D and the case body 11 and a second shielding member 5D2 disposed between the electrode body 2D and the lid 12, and is configured to shield ejected material SP toward the case body 11 and the lid 12 due to a short circuit TR between the positive electrode body 21 and the negative electrode body 22, etc. The first shielding member 5D1 is formed into a bottomed rectangular tube shape by integrally connecting a shielding portion 51D on the short side wall, a shielding portion 53 on the long side wall, and a shielding portion 54D on the bottom wall. The second shielding member 5D2 includes a flat shielding portion 55D on the lid side and an outer peripheral abutment portion 55D1 that abuts against the upper outer peripheral portions of the shielding portion 51D on the short side wall and the shielding portion 53 on the long side wall.

[0038] Furthermore, tab insertion holes 55D3 are formed at both longitudinal end portions (X direction) of the shielding portion 55D on the lid side, through which the tab portion 24 of the positive electrode foil 21H and the tab portion 24 of the negative electrode foil 22H are inserted. The shielding portion 55D also includes an injection port opening 55D5 formed below the injection port 122 formed in the lid 12, and a safety valve opening 55D4 formed below the safety valve 123. These openings facilitate impregnation of the electrode assembly 2 with the electrolyte injected through the injection port 122, and facilitate release from the safety valve 123 of gas pressure that has increased due to a short circuit TR or the like of the electrode assembly 2. The safety valve opening 55D4 may be formed in the shape of perforations that can be opened by gas pressure.

[0039] In addition, it is preferable that the shielding member 5D comprises shielding portions 51D, 54D, 55D (here, corresponding to the shielding portion 51D on the short side wall side, the shielding portion 54D on the bottom wall side, and the shielding portion 55D on the lid side) that face the electrode body open edge portion 2T where the edge portion 21T of the positive electrode body 21 and the edge portion 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2, and a shielding support portion 52 that supports each of the shielding portions 51D, 54D, 55D while spacing them from the inner wall surface 1N of the battery case 1.

[0040] 8 and 9, ejected material SP generated by a short circuit TR between the positive electrode body 21 and the negative electrode body 22 or the like is ejected in large quantities from the electrode body open edge 2T where the edge 21T of the positive electrode body 21 and the edge 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2, and therefore, by having each shielding portion 51D, 54D, 55D face the electrode body open edge 2T, the ejected material SP can be more effectively shielded. In addition, since the shielding support portion 52 is provided, which supports the shielding portions 51D, 54D, 55D while separating them from the inner wall surface 1N of the battery case 1, an air layer KS is formed between the shielding portions 51D, 54D, 55D and the battery case 1, making it difficult for heat from the ejected material SP to be transferred from the shielding portions 51D, 54D, 55D to the inner wall surface 1N of the battery case 1. Therefore, the heat of the ejected material SP can be blocked more effectively, and melting and splitting of the battery case 1 can be further reduced.

[0041] As shown in FIGS. 8 and 9, the shielding member 5D (5D1, 5D2) is preferably formed by covering a metal member 5K having a melting point higher than the higher of the melting points of the positive electrode foil 21H and the negative electrode foil 22H with an insulating member 5Z. The shielding member 5 may also be formed of an insulating inorganic material 5M having a melting point higher than the higher of the melting points of the positive electrode foil 21H and the negative electrode foil 22H. In the electrode assembly 2D stacked in a rectangular parallelepiped shape, the shielding portion 51D on the short side wall side, the shielding portion 54D on the bottom wall side, and the shielding portion 55D on the lid side, from which ejected material SP is likely to be ejected, are formed by covering the metal member 5K with the insulating member 5Z. The other shielding portion 53 surrounding the electrode assembly 2 may be an insulating film 6 formed solely of the insulating member 5Z, and the two may be connected or integrally formed.

[0042] <Description of Secondary Battery According to Third Example> Next, the configuration of a secondary battery according to a third example of an aspect of an embodiment of the disclosed technology will be described in detail with reference to the drawings. Fig. 11 shows a schematic cross-sectional view of a secondary battery according to a third example of an aspect of this embodiment. Fig. 12 shows an E-E cross-section shown in Fig. 11. Fig. 13 shows an F-F cross-section shown in Fig. 11. Fig. 14 shows a schematic perspective view of a shielding member in the secondary battery shown in Fig. 11.

[0043] As shown in FIGS. 11 to 14, a secondary battery 10E according to the third embodiment includes a battery case 1E, an electrode assembly 2E, a current collecting terminal 4E, and a shielding member 5E. Components common to the secondary battery 10 according to the first embodiment are designated by common reference numerals, and their description will be omitted. The battery case 1E includes a rectangular cylindrical case body 11E having rectangular openings 111E at both ends in the longitudinal direction (X direction) and a flat lid 12E (12E1, 12E2) that seals both openings 111E. An injection port 122 and a safety valve 123 are formed in the upper wall 11Eb of the case body 11E. An insertion hole 121E for the current collecting terminal 4E is formed in the center of the lid 12E in the vertical direction (Y direction). An external terminal 41E of the current collecting terminal 4E inserted into the insertion hole 121E is fixed via an insulating resin member 3E. The insulating resin member 3E may be made of, for example, polyphenylene sulfide (PPS) resin.

[0044] In addition, in the electrode body 2E here, strip-shaped positive electrode bodies 21 and negative electrode bodies 22 are stacked with a strip-shaped separator 23 sandwiched between them and wound in a flat shape, but for example, rectangular positive electrode bodies 21 and negative electrode bodies 22 may be stacked in a rectangular parallelepiped shape with a rectangular separator 23 sandwiched between them. A tab portion 24E of the positive electrode foil 21H and a tab portion 24E of the negative electrode foil 22H are formed in the center of both ends in the longitudinal direction (X direction) of the electrode body 2E. The tab portion 24E of the positive electrode foil 21H is joined to an internal terminal 42E of the positive electrode current collector terminal 4EA, and the tab portion 24E of the negative electrode foil 22H is joined to an internal terminal 42E of the negative electrode current collector terminal 4EB.

[0045] The shielding member 5E includes a first shielding member 5E1 arranged between the electrode body 2E and the case body 11E and lid body 12E above a dividing line 5E3 formed in the center of the insertion hole 121E, and a second shielding member 5E2 arranged between the electrode body 2E and the case body 11E and lid body 12E below the dividing line 5E3, and is formed to shield ejected material SP ejected toward the case body 11E and lid body 12E due to a short circuit TR between the positive electrode body 21 and the negative electrode body 22, etc. The first shielding member 5E1 is formed in the shape of an apex-rectangular tube, with a shielding portion 51E on the lid body side, a shielding portion 53E (53E1) on the long side wall side, and a shielding portion 55E on the top wall side being integrally connected. The second shielding member 5E2 is formed into a bottomed rectangular tube shape by integrally connecting a cover-side shielding portion 51E, a long-side wall-side shielding portion 53E (53E2), and a bottom wall-side shielding portion 54E. The first shielding member 5E1 and the second shielding member 5E2 abut against each other at a parting line 5E3.

[0046] The shielding portion 55E on the upper wall side of the first shielding member 5E1 is provided with an injection port opening 55E5 formed below the injection port 122 and a safety valve opening 55E4 formed below the safety valve 123. This makes it easier to impregnate the electrode body 2 with the electrolyte injected from the injection port 122 and makes it easier to release the gas pressure that has increased due to a short circuit TR or the like of the electrode body 2 from the safety valve 123. The safety valve opening 55E4 may be formed in a perforated shape that can be opened by gas pressure.

[0047] In addition, it is preferable that the shielding member 5E comprises a shielding portion 51E (here, this corresponds to the shielding portion 51E on the lid body side) that faces the electrode body open edge portion 2T where the edge portion 21T of the positive electrode body 21 and the edge portion 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2, and a shielding support portion 52 that supports the shielding portion 51E while spacing it from the inner wall surface 1EN of the battery case 1E.

[0048] 13 , ejected material SP generated by a short circuit TR between the positive electrode body 21 and the negative electrode body 22 or the like is ejected in large quantities from the electrode body open edge 2T, where the edge 21T of the positive electrode body 21 and the edge 22T of the negative electrode body 22 are open in a direction perpendicular to the stacking direction of the electrode body 2. Therefore, by having the shielding portion 51E face the electrode body open edge 2T, the ejected material SP can be more effectively shielded. Furthermore, since the shielding support portion 52 is provided, which supports the shielding portion 51E while spacing it from the inner wall surface 1EN of the battery case 1E, an air layer KS is formed between the shielding portion 51E and the battery case 1E, making it difficult for the heat of the ejected material SP to be transferred from the shielding portion 51E to the inner wall surface 1EN of the battery case 1E. Therefore, the heat of the ejected material SP can be more effectively shielded, further reducing melting and cracking of the battery case 1E.

[0049] 12 and 13, the shielding member 5E (5E1, 5E2) is preferably formed by covering a metal member 5K having a melting point higher than the higher of the melting points of the positive electrode foil 21H and the negative electrode foil 22H with an insulating member 5Z. Alternatively, the shielding member 5E may be formed of an insulating inorganic material 5M having a melting point higher than the higher of the melting points of the positive electrode foil 21H and the negative electrode foil 22H. In the electrode body 2E stacked in a rectangular parallelepiped shape, the shielding portion 51E on the lid side, the shielding portion 55E on the top wall side, and the shielding portion 54E on the bottom wall side, from which ejected material SP is likely to be ejected, are formed by covering the metal member 5K with the insulating member 5Z. The other shielding portion 53E surrounding the electrode body 2E is an insulating film 6 formed solely of the insulating member 5Z, and the two may be connected or integrally formed.

[0050] <Modification> The present embodiment described in detail above is merely an example and does not limit the disclosed technology in any way. Therefore, the disclosed technology can be improved and modified in various ways without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0051] 1, 1D, 1E battery case 2, 2D, 2E electrode body 2T electrode body open edge 5, 5B, 5C, 5D, 5E Shielding members 5K metal parts 5M Insulating inorganic material 5Z Insulating material 6. Insulating film 10, 10B, 10C, 10D, 10E secondary battery 21 Cathode 21H positive electrode foil 21K positive electrode active material layer 21T Edge 22 negative electrode body 22H negative electrode foil 22K negative electrode active material layer 22T edge 23 Separator 51, 51D, 51E shielding part 53, 53B Shielding part 54, 54B, 54D, 54E shielding part 55, 55D, 55E shielding part 52 Shield support part

Claims

1. an electrode assembly in which a positive electrode body in which a positive electrode foil is coated with a positive electrode active material layer and a negative electrode body in which a negative electrode foil is coated with a negative electrode active material layer are stacked with a separator sandwiched therebetween; a battery case that houses and seals the electrode assembly; a shielding member disposed between the electrode body and the battery case, for shielding ejected material from the electrode body toward the battery case. Secondary battery.

2. 2. The secondary battery according to claim 1, The shielding member is a shielding portion that faces an open edge portion of the electrode body where the edge portion of the positive electrode body and the edge portion of the negative electrode body are open in a direction perpendicular to the stacking direction of the electrode body; a shielding support part that supports the shielding part while separating it from the inner wall surface of the battery case. Secondary battery.

3. The secondary battery according to claim 1 or 2, The shielding member is formed by covering a metal member having a melting point higher than the higher of the melting points of the positive electrode foil and the negative electrode foil with an insulating member, or by using an insulating inorganic material having a melting point higher than the higher of the melting points of the positive electrode foil and the negative electrode foil. Secondary battery.

4. 2. The secondary battery according to claim 1, The shielding member is connected to or integrally formed with an insulating film surrounding the electrode body. Secondary battery.

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