Non-aqueous electrolyte secondary battery

Abstract

A secondary battery (10) comprises a bottomed cylindrical exterior body (16) that has an opening part, a sealing body (18) for sealing the opening part, an electrode body 12 that is accommodated in the exterior body (16), an electrolytic solution that is accommodated in the exterior body (16), and an insulating member (20) that is accommodated in the exterior body (16). The secondary battery (10) is characterized in that: the exterior body (16) has a groove part (26) formed therein, where a part of a side surface of the exterior body (16) is recessed inward thereof to support the sealing body (18); the insulating member (20) has a flat plate part (22) positioned between the electrode body (12) and the groove part (26), and a protruding part (24) protruding from the sealing body-side surface of the flat plate part (22), the protruding part (24) contacting the inner wall of the groove part (26); and the length of the protruding part (24) from one end of the protruding part (24) on the flat plate part (22) side to the tip of the protruding part (24) is longer than the length in the vertical direction from the sealing body-side surface of the flat plate part (22) to the upper surface of the groove part (26) on the inner wall side.

Description

Non-aqueous electrolyte secondary battery

[0001] The present invention relates to a non-aqueous electrolyte secondary battery.

[0002] The secondary battery includes a cylindrical exterior body with a bottom that houses an electrode assembly and an electrolyte solution. The secondary battery is assembled by housing the electrode assembly in the exterior body, injecting the electrolyte solution, and sealing the opening of the exterior body with a sealing member.

[0003] The side of the exterior body has a recessed groove formed inward (see, for example, Patent Document 1). By forming the groove in the exterior body, for example, during the sealing operation, the sealing body can be placed on the upper surface of the inner wall of the groove, so the sealing operation can be performed stably without tilting the sealing body. Furthermore, after the secondary battery is assembled, the sealing body is supported by the groove, which prevents the sealing body from shifting or falling into the exterior body due to, for example, an external impact.

[0004] International Publication No. 2019 / 054312

[0005] When the electrolyte is poured into the exterior body, the level of the electrolyte may temporarily exceed the upper surface of the inner wall of the groove, causing the electrolyte to remain on the upper surface of the inner wall of the groove. This may result in the electrolyte leaking out of the battery through the gap between the groove and the sealing body during the sealing process or after the secondary battery is assembled. Even if the electrolyte does not remain on the upper surface of the inner wall of the groove, the electrolyte may penetrate the upper surface of the inner wall of the groove and leak out of the battery through the gap between the groove and the sealing body after the secondary battery is assembled.

[0006] Therefore, an object of the present disclosure is to provide a secondary battery that can suppress leakage of electrolyte.

[0007] One aspect of the present disclosure is a secondary battery comprising: a bottomed cylindrical outer casing having an opening; a sealing body that seals the opening; an electrode body contained within the outer casing and having a positive electrode, a negative electrode, and a separator arranged between the positive electrode and the negative electrode; an electrolyte contained within the outer casing; and an insulating member contained within the outer casing, wherein a portion of the side of the outer casing is recessed into the inside of the outer casing to form a grooved portion that supports the sealing body; the insulating member has a flat portion located between the electrode body and the grooved portion and a protruding portion that protrudes from the sealing body side surface of the flat portion, the protruding portion abutting the inner wall of the grooved portion, and the length of the protruding portion from one end of the protruding portion on the flat portion side to the tip of the protruding portion is longer than the vertical length from the sealing body side surface of the flat portion to the upper surface of the inner wall side of the grooved portion.

[0008] According to the present disclosure, a secondary battery capable of suppressing leakage of electrolyte can be provided.

[0009] Fig. 1 is a cross-sectional view of a secondary battery as an example of an embodiment; Fig. 2 is a cross-sectional view for explaining an assembly process of a secondary battery; Fig. 3 is a cross-sectional view for explaining an assembly process of a secondary battery; Fig. 4 is a partially enlarged cross-sectional view showing an insulating member and a grooved portion;

[0010] An example of a secondary battery according to one aspect of the present disclosure will be described below. The drawings referred to in the following description of the embodiment are schematic, and the dimensional ratios of the components depicted in the drawings may differ from those of the actual battery.

[0011] Fig. 1 is a cross-sectional view of a secondary battery according to an embodiment. The secondary battery 10 shown in Fig. 1 is configured to include an electrode assembly 12, an electrolyte (not shown), a battery case 14, and an insulating member 20. The battery case 14 has an opening and includes a bottomed, cylindrical exterior body 16 that houses the electrode assembly 12, the electrolyte, the insulating member 20, etc., and a sealing body 18 that seals the opening of the exterior body 16. For ease of explanation, the sealing body 18 side will be referred to as the "top" and the bottom side of the exterior body 16 will be referred to as the "bottom."

[0012] Although not shown in the drawings, the electrode assembly 12 has a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes. Specific examples include a wound electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, and a stacked electrode assembly in which positive electrodes and negative electrodes are alternately stacked with a separator interposed therebetween.

[0013] Furthermore, for example, a positive electrode lead (not shown) is joined to the positive electrode. The positive electrode lead is, for example, led out from the upper end of the electrode body 12 to above the electrode body 12 and joined to the sealing body 18. In other words, the top plate of the sealing body 18 serves as the positive electrode terminal. Furthermore, for example, a negative electrode lead (not shown) is joined to the negative electrode. The negative electrode lead is, for example, led out from the lower end of the electrode body 12 to below the electrode body 12 and joined to the bottom of the exterior body 16. In other words, the exterior body 16 serves as the negative electrode terminal.

[0014] The electrolyte solution has, for example, lithium ion conductivity. The electrolyte solution includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. The electrolyte salt includes, for example, LiPF ６ Lithium salts such as

[0015] The exterior body 16 may be, for example, a cylindrical or rectangular metal container with a bottom. The exterior body 16 has a grooved portion 26 in which a portion of the side surface of the exterior body 16 is recessed into the interior of the exterior body 16 and supports the sealing body 18. The grooved portion 26 is formed, for example, by pressing a portion of the side surface of the exterior body 16 from the outside. The grooved portion 26 is preferably formed in an annular shape along the circumferential direction of the exterior body 16.

[0016] The opening of the exterior body 16 is sealed by a sealing body 18. As shown in Fig. 1, in order to improve the sealing performance of the inside of the battery, it is preferable to provide a gasket 28 between the exterior body 16 and the sealing body 18. In Fig. 1, the sealing body 18 is supported by the upper surface of the inner wall of the grooved portion 26 via the gasket 28.

[0017] 1 is, for example, a metal plate member. The configuration of sealing body 18 is not particularly limited, and may include, for example, a current interruption mechanism that interrupts current flowing through the battery when the internal pressure of the battery reaches a predetermined value or a gas exhaust mechanism that exhausts gas from inside the battery.

[0018] The insulating member 20 shown in Fig. 1 is disposed above the electrode body 12. Although the insulating member 20 is shown separated from the electrode body 12 in Fig. 1, in practice, it is desirable that the insulating member 20 be disposed so as to contact the upper end of the electrode body 12. Although not shown in the drawings, an insulating plate may be provided between the electrode body 12 and the bottom of the exterior body 16.

[0019] The insulating member 20 shown in FIG. 1 has a flat plate portion 22 located between the electrode body 12 and the grooved portion 26, and a protruding portion 24 protruding from the surface of the flat plate portion 22 facing the sealing body. The insulating member 20 is, for example, a member made of resin. A through-hole (not shown) is desirably formed in a portion of the flat plate portion 22. The positive electrode lead extending from the upper end of the electrode body 12 as described above is connected to the sealing body 18, for example, through the through-hole in the flat plate portion 22.

[0020] The protrusion 24 abuts against the inner wall of the grooved portion 26. When the grooved portion 26 is formed in an annular shape along the circumferential direction of the exterior body 16, the protrusion 24 is preferably also formed in an annular shape along the annular grooved portion 26. The annular protrusion 24 preferably abuts against the entire circumference of the annular grooved portion 26. When a through hole is formed in the flat plate portion 22, the protrusion 24 is preferably provided outside the through hole. The protrusion 24 shown in FIG. 1 is inclined with respect to the surface of the flat plate portion 22 facing the sealing body, but this is not limited thereto and the protrusion 24 may be upright with respect to the surface of the flat plate portion 22 facing the sealing body. When the protrusion 24 is inclined, it is preferably inclined toward the center of the flat plate portion 22 (i.e., toward the inside of the exterior body 16). As described below, the protrusion 24 is provided to prevent the electrolyte from penetrating into the upper surface of the inner wall of the grooved portion 26.

[0021] 5 is a partially enlarged cross-sectional view showing the insulating member and the grooved portion. As shown in FIG. 5, the length L of the protrusion 24 from one end of the protrusion 24 on the flat portion 22 side to the tip of the protrusion 24 is longer than the vertical length H from the sealing body-side surface 22a of the flat portion 22 to the inner wall-side upper surface 26a of the grooved portion 26, and L / H is preferably 1.1 to 2.0, more preferably 1.2 to 1.8, and even more preferably 1.3 to 1.6. The tip of the protrusion 24 is preferably located higher than the position of the inner wall-side upper surface 26a of the grooved portion 26.

[0022] 2 to 4 are cross-sectional views illustrating the assembly process of a secondary battery. As shown in FIG. 2, after the electrode assembly 12 is housed in the exterior housing 16, an insulating member 20 having a flat portion 22 and a protruding portion 24 is placed on the upper end of the electrode assembly 12. At this time, the protruding portion 24 faces the opening of the exterior housing 16. Next, as shown in FIG. 3, a groove 26 is formed on the side surface of the exterior housing 16. At this time, the deepest portion of the inner wall of the groove 26 (the portion that is most recessed into the interior of the exterior housing) is brought into contact with the protruding portion 24 of the insulating member 20. As shown in FIG. 3, when forming the groove 26 of the exterior housing 16, the deepest portion of the inner wall of the groove 26 may press the protruding portion 24 of the insulating member 20 against the protruding portion 24, causing it to tilt inward of the exterior housing 16. In this state, an electrolyte is injected into the interior of the exterior housing 16. When the electrolyte is injected, the level of the electrolyte may temporarily rise to the upper surface of the inner wall of the grooved portion 26 or to a higher position (for example, the position of the dashed line in FIG. 3 ) (the electrolyte is then absorbed into the electrode body 12, and the level of the electrolyte drops). In this embodiment, as described above, the length L of the protruding portion 24 is longer than the length H in the vertical direction from the sealing body side surface 22 a of the flat plate portion 22 to the upper surface 26 a on the inner wall side of the grooved portion 26, so that even if the level of the electrolyte rises, the electrolyte can be prevented from penetrating to the upper surface 26 a of the grooved portion 26. Furthermore, as described above, by setting the ratio of the length L of the protrusion 24 to the vertical length H from the sealing body-side surface 22 a of the flat portion 22 to the upper surface 26 a on the inner wall side of the grooved portion 26 to be 1.1 or more and 2.0 or less, in the state shown in FIG. 3 , the tip of the protrusion 24 is likely to be maintained higher than the position of the upper surface of the inner wall of the grooved portion 26, thereby further preventing the electrolyte from penetrating into the upper surface of the grooved portion 26. Furthermore, because the protrusion 24 of the insulating member 20 abuts the inner wall of the grooved portion 26, it is also possible to prevent the electrolyte from running down the inner wall of the exterior body 16 and penetrating into the upper surface of the grooved portion 26. Then, as shown in FIG. 4 , by placing the sealing body 18 in the opening of the exterior body 16 via the gasket 28 and crimping the end of the exterior body 16 on the opening side, the opening of the exterior body 16 is sealed by the sealing body 18, as shown in FIG. 1 .Furthermore, when the total battery height is adjusted after sealing, the width of the grooved portion 26 becomes smaller, and the deepest part of the inner wall of the grooved portion 26 is pushed into the inside of the outer casing 16, and as a result, the protrusion 24 abutting the inner wall of the grooved portion 26 may be tilted further inward toward the inside of the outer casing 16.

[0023] In the present embodiment, as described above, the electrolyte is prevented from remaining on the upper surface 26a of the inner wall of the grooved portion 26, which prevents the electrolyte from leaking out of the battery through a gap between the grooved portion 26 and the sealing body 18 (effectively, between the grooved portion 26 and the gasket) during the sealing operation or after assembly of the secondary battery 10. Furthermore, even after assembly of the secondary battery 10, the protruding portion 24 of the insulating member 20 prevents the electrolyte from flowing onto the upper surface 26a of the inner wall of the grooved portion 26, which also prevents the electrolyte from leaking out of the battery through a gap between the grooved portion 26 and the sealing body 18 (effectively, between the grooved portion 26 and the gasket 28).

[0024] 1, when a gasket 28 is disposed between the sealing body 18 and the exterior body 16, it is desirable that the protrusion 24 abuts against the gasket 28. This further prevents the electrolyte from flowing onto the upper surface 26a of the inner wall of the grooved portion 26 after the secondary battery 10 is assembled, thereby further preventing the electrolyte from passing between the grooved portion 26 and the gasket 28 and leaking out of the battery.

[0025] The positive electrode, negative electrode, and separator that constitute the electrode assembly will be described below.

[0026] The positive electrode includes a positive electrode current collector and a positive electrode composite layer disposed on the positive electrode current collector. The positive electrode current collector may be, for example, a foil of a metal such as aluminum that is stable within the potential range of the positive electrode, or a film with such a metal disposed on its surface. The positive electrode composite layer preferably contains, for example, a positive electrode active material, a conductive material, and a binder. The positive electrode is fabricated, for example, by applying a positive electrode composite slurry containing the positive electrode active material and the like onto the positive electrode current collector, drying the slurry, and then compressing the resulting positive electrode composite layer.

[0027] Examples of the positive electrode active material include lithium (Li) and Li composite oxides containing transition metal elements such as cobalt (Co), manganese (Mn), and nickel (Ni). The Li composite oxides may contain additional elements other than Co, Mn, and Ni, such as aluminum (Al), zirconium (Zr), boron (B), magnesium (Mg), scandium (Sc), yttrium (Y), titanium (Ti), iron (Fe), copper (Cu), zinc (Zn), chromium (Cr), lead (Pb), tin (Sn), sodium (Na), potassium (K), barium (Ba), strontium (Sr), calcium (Ca), tungsten (W), molybdenum (Mo), niobium (Nb), and silicon (Si).

[0028] Examples of the conductive material include carbon powders such as carbon black, acetylene black, ketjen black, graphite, etc. These may be used alone or in combination of two or more.

[0029] Examples of binders include fluorine-based resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide (PI), acrylic resins, polyolefin resins, styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyethylene oxide (PEO), etc. These may be used alone or in combination of two or more.

[0030] The negative electrode includes a negative electrode current collector and a negative electrode composite layer disposed on the negative electrode current collector. The negative electrode current collector can be a foil of a metal, such as copper, that is stable within the potential range of the negative electrode, or a film with such a metal disposed on its surface. The negative electrode composite layer preferably contains, for example, a negative electrode active material and a binder. The negative electrode is fabricated, for example, by applying a negative electrode composite slurry containing the negative electrode active material and the like to both sides of the negative electrode current collector, drying the slurry, and compressing the resulting negative electrode composite layer.

[0031] The negative electrode active material is not particularly limited as long as it can reversibly absorb and release lithium ions, and examples thereof include carbon materials such as natural graphite and artificial graphite, lithium-titanium composite oxides, metals that alloy with lithium such as Si and Sn, or alloys and composite oxides containing these. Examples of binders include the same materials as those used in the positive electrode. The negative electrode composite layer may contain a conductive material, etc., as necessary.

[0032] The separator may be, for example, a porous sheet having ion permeability and insulating properties. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Suitable materials for the separator include olefin-based resins such as polyethylene and polypropylene, and cellulose. The separator may be a laminate having a cellulose fiber layer and a thermoplastic resin fiber layer such as an olefin-based resin. Alternatively, the separator may be a multilayer separator including a polyethylene layer and a polypropylene layer, and a separator whose surface is coated with a material such as an aramid-based resin or ceramic may be used.

[0033] The present disclosure will be further described by the following embodiments. Configuration 1: A secondary battery comprising: a bottomed cylindrical exterior body having an opening, a sealing body that seals the opening, an electrode assembly housed within the exterior body and having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, an electrolyte solution housed within the exterior body, and an insulating member housed within the exterior body, wherein a portion of a side surface of the exterior body is recessed into the interior of the exterior body to form a groove that supports the sealing body, the insulating member has a flat plate portion located between the electrode body and the groove portion and a protruding portion that protrudes from a surface of the flat plate portion facing the sealing body, the protruding portion abuts an inner wall of the groove portion, and the length of the protruding portion from one end of the protruding portion on the flat plate portion side to the tip of the protruding portion is longer than the vertical length from the surface of the flat plate portion facing the sealing body to an upper surface of the inner wall of the groove portion. Configuration 2: The secondary battery according to Configuration 1, wherein L / H is 1.1 or more and 2.0 or less, where H is the length in the vertical direction and L is the length of the protrusion.Configuration 3: The secondary battery according to Configuration 1 or 2, wherein the groove is formed in an annular shape along the circumferential direction of the side surface of the exterior body, and the protrusion is formed in an annular shape along the annular groove and abuts against the annular groove over the entire circumference.Configuration 4: The secondary battery according to any one of Configurations 1 to 3, wherein a tip of the protrusion is located at a position higher than the position of an upper surface of the inner wall of the groove.

[0034] REFERENCE SIGNS LIST 10 secondary battery, 12 electrode body, 14 battery case, 16 exterior body, 18 sealing body, 20 insulating member, 22 flat plate portion, 22a sealing body side surface, 24 protrusion portion, 26 grooved portion, 26a upper surface, 28 gasket

Claims

1. A secondary battery comprising: a bottomed cylindrical exterior body having an opening; a sealing body that seals the opening; an electrode body housed inside the exterior body and having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; an electrolytic solution housed inside the exterior body; and an insulating member housed inside the exterior body, wherein a part of the side surface of the exterior body is recessed inside the exterior body to form a groove portion that supports the sealing body, the insulating member has a flat plate portion positioned between the electrode body and the groove portion, and a protruding portion protruding from the surface of the flat plate portion on the sealing body side, the protruding portion abuts against the inner wall of the groove portion, and the length of the protruding portion from one end of the protruding portion on the flat plate portion side to the tip of the protruding portion is longer than the vertical length from the surface of the flat plate portion on the sealing body side to the upper surface on the inner wall side of the groove portion.

2. The secondary battery according to claim 1, wherein when the vertical length is H and the length of the protruding portion is L, L / H is 1.1 or more and 2.0 or less.

3. The secondary battery according to claim 1 or 2, wherein the groove portion is formed in an annular shape along the circumferential direction of the side surface of the exterior body, the protruding portion is formed in an annular shape along the annular groove portion, and the protruding portion abuts against the entire circumference of the annular groove portion.

4. The secondary battery according to claim 1 or 2, wherein the tip of the protruding portion is at a position higher than the position of the upper surface of the inner wall of the groove portion.

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