Battery safety mechanism and battery

Abstract

A battery safety mechanism 10 is provided with: a lid 1; a pressure release member 2 that is in contact with the lid 1 and that deforms to release gas inside the battery to the outside thereof when the battery internal pressure is increased; a current blocking member 3 that is disposed on the opposite side to the lid 1 with respect to the pressure release member 2, and is connected to the pressure release member 2 to block a current flow to the pressure release member 2 when the battery internal pressure is increased; and an insulating layer 4 that is interposed between the pressure release member 2 and the current blocking member 3. The pressure release member 2 comprises at least one groove 21, 22 that is open on the current blocking member 3 side and is located between, in a direction orthogonal to a stacking direction of the lid 1, the pressure release member 2, the current blocking member 3, and the insulating layer 4, a position in which the pressure release member 2 and the current blocking member 3 are connected and a position in which the pressure release member 2 is in contact with the lid 1.

Description

[Technical Field]

[0001] The present invention relates to a battery safety mechanism and a battery. [Background technology]

[0002] With the widespread use of various electronic devices, such as mobile phones and personal digital assistants (PDAs), there is a demand for smaller, lighter, and longer-lasting electronic devices. Therefore, development of batteries, particularly secondary batteries, which are small, lightweight, and capable of achieving high energy density, is underway as a power source. Secondary batteries equipped with a safety mechanism for releasing gases generated by decomposition of the electrolyte, etc., are also known.

[0003] A battery equipped with such a safety mechanism is disclosed in Patent Document 1. Fig. 10 is a diagram schematically showing a safety mechanism 200 and its surrounding configuration in the battery disclosed in Patent Document 1.

[0004] As shown in FIG. 10, the battery safety mechanism 200 disclosed in Patent Document 1 includes a battery cover 201, a disk plate 202 that deforms when the battery's internal pressure increases and has a pressure release function for releasing gas inside the battery to the outside, a current interrupting member 203 that interrupts current when the battery's internal pressure increases, and an insulating disk holder 204 interposed between the disk plate 202 and the current interrupting member 203. The current interrupting member 203 includes an interrupting disk 203a and a sub-disk 203b. The disk plate 202 has a protrusion 202a that protrudes toward the current interrupting member 203. The protrusion 202a is connected to the sub-disk 203b via a hole 203c provided in the interrupting disk 203a. The disk plate 202 also has a groove that opens toward the battery cover 201 so that it breaks when the battery's internal pressure increases.

[0005] In this battery safety mechanism 200, when the internal pressure of the battery increases, the disk plate 202 is lifted toward the battery lid 201, and the protrusion 202a comes off from the sub-disk 203b connected to the positive electrode lead 210, thereby cutting off the current flowing to the disk plate 202 and the battery lid 201. In addition, the disk plate 202 is pushed toward the battery lid 201 and breaks at the position where the groove is provided, causing gas generated inside the battery to flow toward the battery lid 201 and be discharged to the outside through a hole provided in the battery lid 201. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2018 / 042777 Summary of the Invention [Problem to be solved by the invention]

[0007] In the safety mechanism 200 described in Patent Document 1, as described above, in order to realize a configuration in which the disk plate 202 is lifted toward the battery lid 201 and breaks when the internal pressure of the battery rises, a space 220 is provided between the disk plate 202 and the battery lid 201. Specifically, the center of the battery lid 201 has a structure that protrudes outward, and the disk plate 202 has a bent portion 202r that is bent toward the shutoff disk 203a, thereby forming the space 220 necessary for the disk plate 202 to break.

[0008] If the disk plate 202 breaks with a smaller displacement when the internal pressure of the battery increases and pushes it toward the battery cover 201, the space 220 can be made smaller, thereby making it possible to reduce the thickness of the safety mechanism 200. If the safety mechanism 200 can be made thinner, for example, when the size of the battery is fixed, the sizes of the positive and negative electrodes can be increased, thereby making it possible to increase the capacity.

[0009] The present invention solves the above-mentioned problems and aims to provide a battery safety mechanism having a pressure release member that can break with a smaller amount of displacement when the internal pressure of the battery rises, and a battery equipped with such a battery safety mechanism. [Means for solving the problem]

[0010] The safety mechanism of the battery of the present invention is The lid and a pressure release member in contact with the lid, which deforms when the internal pressure of the battery increases to release gas inside the battery to the outside; a current interruption member that is disposed on the opposite side of the pressure release member from the lid and is connected to the pressure release member, and that interrupts current flowing to the pressure release member when the internal pressure of the battery increases; an insulating layer interposed between the pressure release member and the current interrupting member; Equipped with The pressure release member has at least one groove that opens toward the current-interrupting member, between the position where the pressure release member and the current-interrupting member are connected and the position where the pressure release member and the lid are in contact, in a direction perpendicular to the stacking direction of the lid, the pressure release member, the current-interrupting member, and the insulating layer. [Effects of the Invention]

[0011] According to the battery safety mechanism of the present invention, the pressure release member has at least one groove opening toward the current-interrupting member in a direction perpendicular to the stacking direction of the lid, pressure release member, current-interrupting member, and insulating layer, between the position where the pressure release member and the current-interrupting member are connected and the position where the pressure release member and the lid are in contact, so that the pressure release member is more likely to deform and break when the battery's internal pressure increases. Because the groove opens toward the current-interrupting member, the pressure release member can break with less displacement when the battery's internal pressure increases, compared to a configuration where the groove opens toward the lid. This allows the space between the lid and the pressure release member to be reduced, thereby enabling the battery safety mechanism to be made thinner. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically illustrating the configuration of a battery equipped with a battery safety mechanism according to one embodiment of the present invention. [Figure 2] FIG. 1 is a cross-sectional view schematically illustrating the configuration of a safety mechanism of a battery according to one embodiment of the present invention. [Figure 3] FIG. 2 is an exploded perspective view of a safety mechanism of a battery according to an embodiment of the present invention. [Figure 4] 10 is a plan view of the pressure release member as viewed in the stacking direction from the current interruption member side. FIG. [Figure 5] FIG. 10 is a plan view of a pressure release member in which the first groove and the second groove are arc-shaped, as viewed in the stacking direction from the current interruption member side. [Figure 6] 1(a) to 1(f) are diagrams showing various examples of the cross-sectional shape of the first groove when cut in a direction perpendicular to the extension direction of the first groove. [Figure 7] FIG. 2(a) is a diagram for schematically explaining the current interrupting function of the current interrupting member, and FIG. 2(b) is a diagram for schematically explaining the pressure releasing function of the pressure releasing member. [Figure 8] FIG. 2 is a diagram illustrating the configuration of an electrode body. [Figure 9] 10 is a cross-sectional view schematically showing the configuration of a battery safety mechanism in which the pressure release member has a convex portion and a flat portion, and the current interrupting member has a flat plate shape. FIG. [Figure 10] FIG. 1 is a cross-sectional view that schematically shows a safety mechanism and its surrounding structure in the battery disclosed in Patent Document 1. DETAILED DESCRIPTION OF THE INVENTION

[0013] The features of the present invention will be specifically described below by showing embodiments of the present invention.

[0014] Fig. 1 is a cross-sectional view showing a schematic configuration of a battery 100 equipped with a battery safety mechanism 10 according to one embodiment of the present invention. Fig. 2 is a cross-sectional view showing a schematic configuration of a battery safety mechanism 10 according to one embodiment of the present invention. Fig. 3 is an exploded view of the battery safety mechanism 10.

[0015] Here, the battery 100 will be described as being a cylindrical lithium-ion secondary battery. However, the type of battery 100 is not limited to a lithium-ion battery, and may be other types of batteries such as manganese batteries, nickel-metal hydride batteries, or nickel-cadmium batteries. Furthermore, the battery 100 is not limited to a secondary battery, and may be a primary battery. Furthermore, the shape of the battery 100 is not limited to a cylindrical shape, and may be other shapes such as a square shape or a button shape.

[0016] The battery safety mechanism 10 comprises a lid 1 , a pressure release member 2 , a current interrupting member 3 , and an insulating layer 4 .

[0017] The lid 1 is a member for sealing the opening of the battery can 20, which will be described later. As shown in FIG. 2, the lid 1 has a flat plate portion 1a and a protruding portion 1b that is located at the center of the lid 1 and is surrounded by the flat plate portion 1a, and that protrudes outward from the battery 100. Since the protruding portion 1b of the lid 1 has a shape that protrudes outward from the battery 100, the protruding portion 1b includes a bent portion 1b1 that extends from the flat plate portion 1a toward the outside of the battery 100. The portion of the protruding portion 1b of the lid 1 other than the bent portion 1b1 has a flat plate shape, similar to the flat plate portion 1a.

[0018] The thickness of the lid 1 is, for example, 1.5 mm or more and 3.0 mm or less. In the battery 100 of this embodiment, the lid 1 functions as the positive electrode terminal of the battery 100, and the battery can 20 functions as the negative electrode terminal. The lid 1 and the battery can 20 are insulated from each other. The lid 1 is provided with a discharge hole 1c for discharging gas generated inside the battery 100 to the outside of the battery 100. The lid 1 is made of a conductive material, for example, steel such as SPCC, stainless steel (SUS) such as SUS430 or SUS304, nickel (Ni), aluminum (Al), titanium (Ti), or the like.

[0019] The pressure release member 2 is in contact with the lid 1 and is a member that deforms when the internal pressure of the battery increases, thereby releasing gas inside the battery to the outside. As shown in FIG. 3, the pressure release member 2 has a flat plate shape and its thickness is, for example, 0.2 mm to 0.5 mm. The shape of the pressure release member 2 when viewed in the stacking direction of the lid 1, pressure release member 2, insulating layer 4, and current-blocking member 3 (hereinafter simply referred to as the stacking direction) is circular. However, the shape of the pressure release member 2 is not limited to circular.

[0020] The pressure release member 2 is made of a conductive material such as aluminum (e.g., A1050, A3203, A5052), titanium, platinum (Pt), gold (Au), etc. By making the pressure release member 2 of at least one of aluminum, titanium, platinum, and gold, reactive decomposition within the lithium ion secondary battery can be prevented.

[0021] The pressure release member 2 has at least one groove that opens toward the current-blocking member 3 in a direction perpendicular to the stacking direction, between the position where the pressure release member 2 and the current-blocking member 3 are connected and the position where the pressure release member 2 and the lid 1 are in contact, so that the pressure release member 2 deforms when the internal battery pressure increases. The depth of the groove is, for example, 0.1 mm or more and 0.2 mm or less. The groove may be provided so that the minimum thickness of the pressure release member 2 at the position where the groove is provided is, for example, 0.1 mm or more and 0.2 mm or less in a cross-sectional view taken along the stacking direction. Preferably, the groove may be provided so that the minimum thickness of the pressure release member 2 at the position where the groove is provided is, for example, 0.12 mm or more and 0.18 mm or less.

[0022] As such grooves, the pressure release member 2 in this embodiment has a first groove 21 that opens to the current interrupting member 3 side, and a second groove 22 that opens to the current interrupting member 3 side and is located radially outward from the first groove 21. Because the first groove 21 and the second groove 22 each open to the current interrupting member 3 side, the pressure release member 2 can be broken with a smaller amount of displacement when the internal battery pressure rises, compared to a configuration in which the first groove 21 and the second groove 22 open to the current interrupting member 3 side.

[0023] However, the pressure release member 2 may have only one groove that opens to the current interruption member 3 side, or may have three or more grooves.

[0024] Figure 4 is a plan view of the pressure release member 2 when viewed in the stacking direction from the current interruption member 3 side. As shown in Figure 4, in this embodiment, the first groove 21 and the second groove 22 are both circular when viewed in the stacking direction. Furthermore, the first groove 21 and the second groove 22 form concentric circles.

[0025] However, the shapes of the first grooves 21 and the second grooves 22 when viewed in the stacking direction are not limited to circular. For example, as shown in Fig. 5, the shapes of the first grooves 21 and the second grooves 22 when viewed in the stacking direction may be arc-shaped. Fig. 5 shows an example in which three arc-shaped first grooves 21 and three arc-shaped second grooves 22 are provided, but the number is not limited to three.

[0026] The first groove 21 and the second groove 22 have different depths. Specifically, the first groove 21 is deeper than the second groove 22. Because the first groove 21 is deeper than the second groove 22, the pressure release member 2 breaks at the position where the first groove 21 is provided when the internal pressure of the battery increases. The minimum thickness of the pressure release member 2 at the position where the first groove 21 is provided may be, for example, 0.1 mm or more and 0.19 mm or less, and the minimum thickness of the pressure release member 2 at the position where the second groove 22 is provided may be, for example, 0.11 mm or more and 0.2 mm or less. The minimum thickness of the pressure release member 2 at the position where the first groove 21 is provided may be, for example, 0.12 mm or more and 0.17 mm or less, and the minimum thickness of the pressure release member 2 at the position where the second groove 22 is provided may be, for example, 0.15 mm or more and 0.18 mm or less. For example, when the thickness of the pressure release member 2 is 0.3 mm, the depth of the first groove 21 is 0.11 mm to 0.2 mm, preferably 0.13 mm to 0.18 mm. The depth of the second groove 22 is, for example, 0.1 mm to 0.19 mm, preferably 0.12 mm to 0.15 mm. The difference in depth between the first groove 21 and the second groove 22 is, for example, 0.01 mm to 0.1 mm, preferably 0.01 mm to 0.06 mm.

[0027] As shown in FIG. 2, the second groove 22 of the pressure release member 2 is located near the inner contact edge of the area where the lid 1 and the pressure release member 2 are in contact. "Near the contact edge" refers to a range within 1.5 mm from the contact edge toward the inside in the radial direction (direction perpendicular to the stacking direction). As shown in FIG. 2, the pressure release member 2 is in contact with the flat portion 1a of the lid 1, but is not in contact with the bent portion 1b1. Preferably, the second groove 22 of the pressure release member 2 is located at a position that overlaps with the bent portion 1b1 of the protruding portion 1b of the lid 1 in the stacking direction.

[0028] By positioning the second groove 22 of the pressure release member 2 near the inner contact end of the area where the lid 1 and the pressure release member 2 are in contact, as will be described later, the pressure release member 2 is less likely to deform along the bent portion 1b1 of the lid 1 at the position where the second groove 22 is provided when the internal pressure of the battery increases. This makes it possible to prevent the lid 1 from shifting in position. It also makes it possible to reduce the impact of processing variations on the lid 1. The pressure release member 2 is more likely to break at the position where the first groove 21 is provided.

[0029] 2, in this embodiment, the cross-sectional shape of the first groove 21 when cut in a direction perpendicular to the extension direction of the first groove 21 is trapezoidal. Similarly, the shape of the second groove 22 when cut in a direction perpendicular to the extension direction of the second groove 22 is trapezoidal. Note that in this embodiment, the shape of the first groove 21 when viewed in the stacking direction is circular, and therefore the direction perpendicular to the extension direction of the first groove 21 is the direction perpendicular to the tangent of the circular first groove 21. The same applies to the direction perpendicular to the extension direction of the second groove 22.

[0030] However, the cross-sectional shape of the first groove 21 when cut in a direction perpendicular to the extension direction of the first groove 21 and the cross-sectional shape of the second groove 22 when cut in a direction perpendicular to the extension direction of the second groove 22 are not limited to a trapezoid. FIGS. 6(a) to 6(f) are diagrams showing various examples of the cross-sectional shape of the first groove 21 when cut in a direction perpendicular to the extension direction of the first groove 21. The cross-sectional shape of the first groove 21 may be a semicircle as shown in FIG. 6(b), a rectangle as shown in FIG. 6(c), or a triangle as shown in FIG. 6(d). Furthermore, the cross-sectional shape of the first groove 21 may be a rectangle with an arc-shaped bottom as shown in FIG. 6(a). Furthermore, the cross-sectional shape of the first groove 21 may be a combination of two rectangles with different widths as shown in FIG. 6(e), or a combination of two trapezoids with different base lengths as shown in FIG. 6(f). Similarly, the cross-sectional shape of the second groove 22 can also be the shapes shown in Figures 6(a) to 6(f). The cross-sectional shapes of the first groove 21 and the second groove 22 may be shapes other than the shapes shown in Figure 2 and Figures 6(a) to 6(f). Furthermore, the cross-sectional shapes of the first groove 21 and the second groove 22 may be the same shape or different shapes.

[0031] The current interrupting member 3 is connected to a positive electrode lead 36 extending from the electrode assembly 30 of the battery 100, which will be described later. The current interrupting member 3 is disposed on the opposite side of the pressure release member 2 from the lid 1 and is connected to the pressure release member 2, and is a member for interrupting the current flowing to the pressure release member 2 when the internal pressure of the battery increases. The current interrupting member 3 has an overall flat plate shape. Specifically, as shown in FIGS. 2 and 3 , the current interrupting member 3 has a flat plate portion 3a and a protrusion 3b that is located in the center of the current interrupting member 3 and is surrounded by the flat plate portion 3a, protruding from the flat plate portion 3a toward the pressure release member 2 to connect to the pressure release member 2.

[0032] In this embodiment, the shape of the outer peripheral edge of the current interruption member 3 is circular when viewed in the stacking direction. Furthermore, the shape of the convex portions 3b of the current interruption member 3 is circular when viewed in the stacking direction. The thickness of the flat portion 3a and the convex portions 3b of the current interruption member 3 is, for example, 0.25 mm or more and 0.5 mm or less. The thickness of the convex portions 3b is approximately the same as the thickness of the insulating layer 4 described below, and is, for example, 0.05 mm or more and 0.4 mm or less. The current interruption member 3 is not a completely flat plate because it has the convex portions 3b, but because the thickness of the convex portions 3b is thin, it can be considered to have a flat plate shape overall.

[0033] In this embodiment, the protrusion 3b of the current interrupting member 3 is connected to the pressure release member 2. In this embodiment, the protrusion 3b of the current interrupting member 3 is joined to the pressure release member 2.

[0034] As shown in Fig. 3, the flat plate portion 3a of the current interrupting member 3 may be provided with a plurality of holes 3c for allowing gas generated inside the battery to pass through. In this embodiment, six holes 3c are provided around the periphery of the protruding portion 3b. However, the number of holes 3c is not limited to six, and their shapes are not limited to those shown in Fig. 3. The holes 3c are provided at positions that do not overlap with the first groove 21 and the second groove 22 of the pressure release member 2 in the stacking direction.

[0035] It is also possible to have no hole 3c depending on the shape of the current interruption member 3. The hole 3c may be provided at a position overlapping with the first groove 21 and / or the second groove 22 of the pressure release member 2 in the stacking direction.

[0036] The current interrupting member 3 is made of a conductive material such as aluminum (e.g., A1050, A3203, A5052), titanium, platinum, or gold. By making the current interrupting member 3 of at least one of aluminum, titanium, platinum, and gold, reactive decomposition within the lithium-ion secondary battery can be prevented.

[0037] The current interrupting member 3 has a groove 3d that opens toward the pressure release member 2 in a direction perpendicular to the stacking direction, between the position where the current interrupting member 3 and the pressure release member 2 are connected and the position where the current interrupting member 3 and the insulating layer 4 are in contact. The depth of the groove 3d is, for example, 0.2 mm or more and 0.46 mm or less. In this embodiment, the groove 3d is provided near the protruding portion 3b of the current interrupting member 3 so as to surround the protruding portion 3b. The shape of the groove 3d when viewed in the stacking direction is circular. However, the shape of the groove 3d is not limited to circular and may be other shapes, such as an arc shape.

[0038] FIG. 7(a) is a diagram illustrating the current interruption function of the current interruption member 3, and FIG. 7(b) is a diagram illustrating the pressure release function of the pressure release member 2. When the internal pressure of the battery 100 increases due to an internal short circuit in the battery 100 or external heating of the battery 100, the portion of the current interruption member 3 including the protrusion 3b is detached from the flat plate portion 3a at the position where the groove 3d is formed, as shown in FIG. 7(a). As a result, the portion including the protrusion 3b detached from the flat plate portion 3a is also detached from the positive electrode lead 36 (see FIG. 1), thereby interrupting the current flowing from the positive electrode lead 36 to the pressure release member 2 via the current interruption member 3. Furthermore, as shown in FIG. 7(a), the portion of the pressure release member 2 connected to the protrusion 3b of the current interruption member 3 that is not in contact with the lid 1 deforms and bulges toward the lid 1.

[0039] Furthermore, if the internal pressure of the battery further increases due to gas generated inside the battery 100, the force pushing the pressure release member 2 toward the lid 1 increases, and as shown in Figure 7(b), the pressure release member 2 is cut at the position where the first groove 21 is provided. That is, the pressure release member 2 deforms in the vicinity of the position where the second groove 22 is provided so as to follow the bent portion 1b1 of the lid 1, and is cut at the position where the first groove 21, which is deeper than the second groove 22, is provided. As a result, the gas generated inside the battery 100 flows toward the lid 1 and is discharged to the outside through a hole (not shown) provided in the lid 1.

[0040] As described above, the first groove 21 and the second groove 22 of the pressure release member 2 are open to the current interrupting member 3 side, so that the pressure release member 2 breaks with less displacement when the internal battery pressure rises, compared to a configuration in which they are open to the lid 1 side. This has been confirmed by the inventors through experiments. Therefore, it is possible to reduce the space between the lid 1 and the pressure release member 2, allowing the pressure release member 2 to have a flat plate-like shape. This allows the battery safety mechanism 10 to be made thinner.

[0041] The insulating layer 4, which has insulating properties, is interposed between the pressure release member 2 and the current interrupting member 3. More specifically, the insulating layer 4 is disposed between the pressure release member 2 and the current interrupting member 3, and radially outward of the second groove 22 of the pressure release member 2. By having the insulating layer 4 interposed between the pressure release member 2 and the current interrupting member 3, insulation can be achieved between the pressure release member 2, which is connected to the positive electrode lead 36, and the current interrupting member 3 when the current interrupting function of the current interrupting member 3 is exerted (see FIG. 7(a)).

[0042] In this embodiment, the insulating layer 4 is an adhesive layer that bonds the pressure release member 2 and the current interruption member 3. In this case, the insulating layer 4 is made of any one of a thermosetting resin, a thermoplastic resin, a UV-curable resin, and an anaerobic adhesive. Specifically, the insulating layer 4 can be made of an epoxy resin-based adhesive containing epoxy resin as the main component, an acrylic resin-based adhesive containing acrylic resin as the main component, a fluororesin-based adhesive containing fluororesin as the main component, a silicone resin-based adhesive containing silicone resin as the main component, a synthetic resin-based adhesive containing synthetic resin as the main component, or a urethane resin-based adhesive containing urethane resin as the main component.

[0043] When a thermosetting resin is used for the insulating layer 4, the glass transition temperature Tg is preferably 100°C or higher, more preferably 170°C or higher. Examples of thermosetting resins with a glass transition temperature Tg of 100°C or higher include epoxy resins. When a thermoplastic resin is used for the insulating layer 4, the melting point Tm is preferably 200°C or higher, more preferably 270°C or higher. When the insulating layer 4 is made of a thermosetting resin with a glass transition temperature Tg of 100°C or higher, or a thermoplastic resin with a melting point Tm of 200°C or higher, the insulating layer 4 remains between the pressure release member 2 and the current interrupting member 3 even when the battery temperature reaches a high level of several hundred degrees Celsius. Therefore, when the current interrupting member 3 is performing its current interrupting function (see FIG. 7(a)), the pressure release member 2 connected to the positive electrode lead 36 can be kept in an insulated state from the current interrupting member 3, preventing the occurrence of a short circuit.

[0044] In this embodiment, the insulating layer 4 has a circular ring shape when viewed in the stacking direction, as shown in FIG. 3. However, the shape of the insulating layer 4 when viewed in the stacking direction is not limited to a circular ring shape. The insulating layer 4 can be formed using, for example, a dispenser. The thickness of the insulating layer 4 is, for example, 0.05 mm or more and 0.4 mm or less. The area of the insulating layer 4 is, for example, 0.6 mm 2 More than 100mm 2 The following is the result.

[0045] However, the insulating layer 4 is not limited to an adhesive layer made of an adhesive, and may be made of other materials such as a molding resin.

[0046] [Safety mechanism manufacturing method] An example of a method for manufacturing the above-mentioned safety mechanism 10 will now be described.

[0047] First, the lid 1 is joined to the pressure release member 2. Specifically, the flat plate portion 1a of the lid 1 is joined to the pressure release member 2. Any joining method can be used, and for example, welding such as ultrasonic welding can be used.

[0048] Next, adhesive is applied to at least one of the surface of the pressure release member 2 opposite the lid 1 and the surface of the current interrupting member 3 facing the convex portion 3b, and the pressure release member 2 and the current interrupting member 3 are bonded together with the applied adhesive sandwiched between them. As described above, epoxy resin adhesives, acrylic resin adhesives, fluororesin adhesives, silicone resin adhesives, synthetic resin adhesives, urethane resin adhesives, etc. can be used as the adhesive. The thickness of the applied adhesive is, for example, 0.1 mm or more and 0.4 mm or less, and the area to be applied is, for example, 0.6 mm. 2 More than 100mm 2 As a result, an insulating layer 4 is formed between the pressure release member 2 and the current interrupting member 3.

[0049] Finally, the protrusion 3b of the current interrupting member 3 is connected to the pressure release member 2. Any connection method may be used, and for example, welding such as laser welding may be used.

[0050] Alternatively, the pressure release member 2 and the current interrupting member 3 may be first bonded together with an adhesive, then the convex portion 3b of the current interrupting member 3 may be joined to the pressure release member 2, and finally the lid 1 may be joined to the pressure release member 2.

[0051] [battery] Next, an example of the structure of a battery 100 equipped with the safety mechanism 10 of the present invention will be described. The battery 100 includes the safety mechanism 10, a battery can 20, and an electrode assembly 30.

[0052] In this embodiment, the battery can 20 has a hollow cylindrical shape with one end open, and houses the electrode assembly 30. The battery can 20 is made of, for example, nickel-plated iron (Fe). Nickel, stainless steel, aluminum, titanium, etc. may also be used as the material for the battery can 20. The surface of the battery can 20 may be plated with, for example, nickel to prevent electrochemical corrosion caused by the nonaqueous electrolyte solution during charging and discharging of the nonaqueous electrolyte battery.

[0053] A safety mechanism 10 is attached to the open end of the battery can 20 with the lid 1 facing outward. Specifically, the safety mechanism 10 is attached by crimping to the battery can 20 via a gasket 11 for insulating sealing. This seals the inside of the battery can 20.

[0054] The battery can 20 contains an electrode assembly 30 including a positive electrode 31, a negative electrode 32, and a separator 33 disposed between the positive electrode 31 and the negative electrode 32. In this embodiment, the electrode assembly 30 is a wound electrode assembly in which a pair of strip-shaped positive electrodes 31 and strip-shaped negative electrodes 32 are stacked with the separator 33 interposed between them and wound around a center pin 38. However, the electrode assembly 30 is not limited to a wound electrode assembly. In the battery 100 of the present invention, the electrode assembly 30 may have any configuration.

[0055] A positive electrode lead 36 is connected to the positive electrode 31, and a negative electrode lead 37 is connected to the negative electrode 32. As described above, the positive electrode lead 36 is connected to the current interrupting member 3 of the battery safety mechanism 10, and is electrically connected to the lid 1 via the pressure release member 2. The negative electrode lead 37 is welded to the battery can 20 and is electrically connected to the battery can 20.

[0056] An electrolytic solution serving as a liquid electrolyte is poured into the battery can 20. The electrolytic solution is impregnated into the positive electrode 31, the negative electrode 32, and the separator 33. A pair of insulating plates 34, 35 are arranged perpendicular to the wound circumferential surface so as to sandwich the electrode body 30 therebetween.

[0057] Hereinafter, the positive electrode 31, the negative electrode 32, the separator 33, and the electrolyte that constitute the electrode assembly 30 will be described in order with reference to FIG.

[0058] (positive electrode) The positive electrode 31 has a structure in which, for example, a positive electrode current collector 31A has a positive electrode active material layer 31B provided on both sides thereof. However, the positive electrode active material layer 31B may be provided on only one side of the positive electrode current collector 31A. The positive electrode current collector 31A is made of a metal foil such as aluminum foil, nickel foil, or stainless steel foil. The positive electrode active material layer 31B contains, for example, a positive electrode active material capable of absorbing and releasing lithium, which is an electrode reactant. The positive electrode active material layer 31B may further contain an additive as necessary. For example, at least one of a conductive agent and a binder can be used as the additive.

[0059] Suitable positive electrode materials capable of absorbing and releasing lithium include lithium-containing compounds such as lithium oxide, lithium phosphate, lithium sulfide, and lithium-containing intercalation compounds, and two or more of these may be mixed together. To increase the energy density, it is preferable to use a lithium-containing compound containing lithium, a transition metal element, and oxygen (O). Examples of such lithium-containing compounds include a lithium composite oxide having a layered rock-salt structure represented by formula (A) and a lithium composite phosphate having an olivine structure represented by formula (B). More preferred lithium-containing compounds include those containing at least one transition metal element selected from the group consisting of cobalt (Co), nickel, manganese (Mn), and iron. Examples of such lithium-containing compounds include a lithium composite oxide having a layered rock-salt structure represented by formula (C), formula (D), or formula (E), a lithium composite oxide having a spinel structure represented by formula (F), and a lithium composite phosphate having an olivine structure represented by formula (G). Specific examples include LiNi 0.50 Co 0.20 Mn 0.30 O2, Li a CoO2 (a≒1), Li b NiO2 (b≒1), Li c1 Ni c2 Co 1-c2 O2(c1≒1,0 <c2<1)、Li d Mn2O4 (d≒1) or Li eThere is FePO4(e≈1), etc.

[0060] Li p Ni (1-q-r) Mn q M1 r O (2-y) X z …(A) (However, in formula (A), M1 represents at least one element selected from Groups 2 to 15 excluding nickel and manganese. X represents at least one of Group 16 elements and Group 17 elements other than oxygen. p, q, y, z are values within the ranges of 0≤p≤1.5, 0≤q≤1.0, 0≤r≤1.0, -0.10≤y≤0.20, 0≤z≤0.2.)

[0061] Li a M2 b PO4…(B) (However, in formula (B), M2 represents at least one element selected from Groups 2 to 15. a, b are values within the ranges of 0≤a≤2.0, 0.5≤b≤2.0.)

[0062] Li f Mn (1-g-h) Ni g M3 h O (2-j) F k …(C) (However, in formula (C), M3 represents at least one member of the group consisting of cobalt, magnesium (Mg), aluminum, boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron, copper (Cu), zinc (Zn), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr) and tungsten (W). f, g, h, j and k are values within the ranges of 0.8≤f≤1.2, 0<g<0.5, 0≤h≤0.5, g + h<1, -0.1≤j≤0.2, 0≤k≤0.1. Note that the composition of lithium varies depending on the charge - discharge state, and the value of f represents the value in the fully discharged state.)

[0063] Li m Ni (1-n) M4 n O(2-p) F q …(D) (In formula (D), M4 represents at least one element selected from the group consisting of cobalt, manganese, magnesium, aluminum, boron, titanium, vanadium, chromium, iron, copper, zinc, molybdenum, tin, calcium, strontium, and tungsten. m, n, p, and q are values within the ranges of 0.8≦m≦1.2, 0.005≦n≦0.5, −0.1≦p≦0.2, and 0≦q≦0.1. Note that the composition of lithium varies depending on the state of charge and discharge, and the value of m represents the value in a fully discharged state.)

[0064] Li r Co (1-s) M5 s O (2-t) F u …(E) (In formula (E), M5 represents at least one element selected from the group consisting of nickel, manganese, magnesium, aluminum, boron, titanium, vanadium, chromium, iron, copper, zinc, molybdenum, tin, calcium, strontium, and tungsten. r, s, t, and u are values within the ranges of 0.8≦r≦1.2, 0≦s<0.5, −0.1≦t≦0.2, and 0≦u≦0.1. Note that the composition of lithium varies depending on the state of charge and discharge, and the value of r represents the value in a fully discharged state.)

[0065] Li v Mn 2-w M6 w O x F y …(F) (In formula (F), M6 represents at least one element selected from the group consisting of cobalt, nickel, magnesium, aluminum, boron, titanium, vanadium, chromium, iron, copper, zinc, molybdenum, tin, calcium, strontium, and tungsten. v, w, x, and y are values within the ranges of 0.9≦v≦1.1, 0≦w≦0.6, 3.7≦x≦4.1, and 0≦y≦0.1. Note that the composition of lithium varies depending on the state of charge and discharge, and the value of v represents the value in a fully discharged state.)

[0066] Li z M7PO4…(G) (In formula (G), M7 represents at least one element selected from the group consisting of cobalt, manganese, iron, nickel, magnesium, aluminum, boron, titanium, vanadium, niobium (Nb), copper, zinc, molybdenum, calcium, strontium, tungsten, and zirconium. z is a value within the range of 0.9≦z≦1.1. Note that the composition of lithium varies depending on the state of charge and discharge, and the value of z represents the value in a fully discharged state.)

[0067] In addition to these, other positive electrode materials that can absorb and release lithium include MnO2, V2O5, and V6O 13 Also included are inorganic compounds that do not contain lithium, such as NiS and MOS.

[0068] The positive electrode material capable of absorbing and desorbing lithium may be other than those mentioned above. In addition, two or more of the positive electrode materials exemplified above may be mixed in any combination.

[0069] As the binder, for example, at least one selected from resin materials such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), styrene butadiene rubber (SBR), and carboxymethyl cellulose (CMC), as well as copolymers mainly made of these resin materials, can be used.

[0070] Examples of the conductive agent include carbon materials such as graphite, carbon black, and Ketjen black, and one or more of these may be used in combination. In addition to carbon materials, conductive materials such as metal materials and conductive polymer materials may also be used as the conductive agent.

[0071] (Negative electrode) The negative electrode 32 has a structure in which, for example, a negative electrode active material layer 32B is provided on both sides of a negative electrode current collector 32A. However, the negative electrode active material layer 32B may be provided on only one side of the negative electrode current collector 32A. The negative electrode current collector 32A is made of a metal foil such as copper foil, nickel foil, or stainless steel foil.

[0072] The negative electrode active material layer 32B contains one or more negative electrode active materials capable of absorbing and releasing lithium. The negative electrode active material layer 32B may further contain additives such as a binder and a conductive agent, as necessary.

[0073] In addition, in the battery 100, which is a nonaqueous electrolyte battery, the electrochemical equivalent of the negative electrode 32 or the negative electrode active material is greater than the electrochemical equivalent of the positive electrode 31, and theoretically, it is preferable that lithium metal does not deposit on the negative electrode 32 during charging.

[0074] Examples of negative electrode active materials include carbon materials such as non-graphitizable carbon, graphitizable carbon, graphite, pyrolytic carbons, cokes, glassy carbons, organic polymer compound calcined bodies, carbon fiber, and activated carbon. Examples of cokes include pitch coke, needle coke, and petroleum coke. Calcined organic polymer compounds are carbonized by calcining polymer materials such as phenolic resins and furan resins at appropriate temperatures. Some of these are classified as non-graphitizable carbon or graphitizable carbon. These carbon materials are preferred because they undergo minimal change in their crystalline structure during charge and discharge, allowing for high charge and discharge capacities and good cycle characteristics. Graphite is particularly preferred because it has a large electrochemical equivalent and can achieve high energy density. Non-graphitizable carbon is preferred because it can achieve excellent cycle characteristics. Furthermore, materials with low charge and discharge potentials, specifically those with charge and discharge potentials close to that of lithium metal, are preferred because they can easily achieve high energy densities in the battery 100.

[0075] Other examples of anode active materials that can achieve high capacity include materials containing at least one of a metal element and a metalloid element as a constituent element (e.g., alloy, compound, or mixture). This is because the use of such materials allows for a high energy density. In particular, using such materials together with a carbon material is more preferable, as it allows for a high energy density and excellent cycle characteristics. Note that alloys include those containing one or more metal elements and one or more metalloid elements, in addition to those consisting of two or more metal elements. The anode active material may also contain nonmetallic elements. The structure may be a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or a mixture of two or more of these.

[0076] Examples of the negative electrode active material include metal elements or semimetal elements capable of forming an alloy with lithium. Specific examples include magnesium, boron, aluminum, titanium, gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin, lead (Pb), bismuth (Bi), cadmium (Cd), silver (Ag), zinc, hafnium (Hf), zirconium, yttrium (Y), palladium (Pd), and platinum. These may be crystalline or amorphous.

[0077] The negative electrode active material preferably contains a metal element or a metalloid element of Group 4B in the short periodic table as a constituent element, and more preferably contains at least one of silicon and tin as a constituent element. This is because silicon and tin have a high ability to absorb and release lithium, allowing for high energy density. Examples of such negative electrode active materials include silicon, alloys, or compounds; tin, alloys, or compounds; and materials having at least one or more of these phases in at least a portion thereof.

[0078] Examples of the second element other than silicon that constitutes a silicon alloy include those containing at least one element selected from the group consisting of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony (Sb), and chromium. Examples of the second element other than tin that constitutes a tin alloy include those containing at least one element selected from the group consisting of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium.

[0079] Examples of tin compounds or silicon compounds include those containing oxygen or carbon. In addition to tin or silicon, they may also contain the second constituent element described above.

[0080] Among them, a Sn-based negative electrode active material is preferably a SnCoC-containing material containing cobalt, tin, and carbon as constituent elements, with a carbon content of 9.9% by mass to 29.7% by mass and a cobalt ratio of 30% by mass to 70% by mass relative to the total of tin and cobalt. This is because, within the above composition range, a high energy density and excellent cycle characteristics can be obtained.

[0081] The SnCoC-containing material may further contain other constituent elements as necessary. Examples of the other constituent elements include silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus (P), gallium, and bismuth. The material may contain two or more of the above elements. The inclusion of the above elements among the other constituent elements can further improve the capacity or cycle characteristics.

[0082] The SnCoC-containing material has a phase containing tin, cobalt, and carbon, and this phase preferably has a low crystallinity or amorphous structure. Furthermore, in this SnCoC-containing material, at least a portion of the carbon, which is a constituent element, is preferably bonded to other constituent elements, such as metal elements or metalloid elements. The deterioration of cycle performance is thought to be due to the aggregation or crystallization of tin and other elements, but the carbon can suppress such aggregation or crystallization by bonding with other elements.

[0083] X-ray photoelectron spectroscopy (XPS) is an example of a measurement method for examining the bonding state of elements. In XPS, in the case of graphite, the peak of the carbon 1s orbital (C1s) appears at 284.5 eV when an XPS instrument is energy-calibrated so that the peak of the gold 4f orbital (Au4f) is obtained at 84.0 eV. Furthermore, in the case of surface contaminant carbon, the peak appears at 284.8 eV. In contrast, when the charge density of the carbon element is high, for example, when carbon is bonded to a metal element or a metalloid element, the C1s peak appears in a region lower than 284.5 eV. That is, when the peak of the C1s composite wave obtained for the SnCoC-containing material appears in a region lower than 284.5 eV, at least a portion of the carbon contained in the SnCoC-containing material is bonded to a metal element or a metalloid element, which is another constituent element.

[0084] In XPS measurements, the C1s peak, for example, is used to correct the energy axis of the spectrum. Since surface contaminant carbon is usually present on the surface, the C1s peak of the surface contaminant carbon is set to 284.8 eV, which is used as the energy reference. In XPS measurements, the waveform of the C1s peak is obtained as a waveform that includes the peak of the surface contaminant carbon and the peak of carbon in the SnCoC-containing material. Therefore, the peak of the surface contaminant carbon and the peak of carbon in the SnCoC-containing material are separated by analysis using, for example, commercially available software. In waveform analysis, the position of the main peak on the lowest binding energy side is used as the energy reference (284.8 eV).

[0085] Other examples of the negative electrode active material include metal oxides or polymer compounds capable of absorbing and releasing lithium. Examples of metal oxides include lithium titanate (Li4Ti5O 12 Examples of the polymer compound include lithium titanium oxide containing titanium and lithium, such as titanium dioxide, iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer compound include polyacetylene, polyaniline, and polypyrrole.

[0086] The binder may be at least one selected from resin materials such as polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene butadiene rubber, and carboxymethyl cellulose, or copolymers mainly composed of the above resin materials. The conductive agent may be a carbon material similar to that used in the positive electrode active material layer 31B.

[0087] (separator) The separator 33 separates the positive electrode 31 and the negative electrode 32, preventing short-circuiting due to contact between the electrodes while allowing lithium ions to pass through. The separator 33 is composed of a porous membrane made of a resin such as polytetrafluoroethylene, polypropylene, or polyethylene. The separator 33 may also have a structure in which two or more of the above-mentioned porous membranes are laminated. Among these, a porous membrane made of polyolefin is preferred because it has excellent short-circuit prevention properties and can improve the safety of the battery 100 through its shutdown effect. Polyethylene is particularly preferred as a material for the separator 33 because it can achieve a shutdown effect within a temperature range of 100°C to 160°C and has excellent electrochemical stability. Alternatively, the separator 33 may be made of a material obtained by copolymerizing or blending a chemically stable resin with polyethylene or polypropylene. The porous membrane may have a three-layer or more structure in which a polypropylene layer, a polyethylene layer, and a polypropylene layer are sequentially laminated.

[0088] The separator 33 may have a resin layer provided on one or both sides of a porous membrane substrate. The resin layer is a porous matrix resin layer carrying an inorganic substance. Such a structure can provide oxidation resistance and suppress deterioration of the separator 33. Examples of the matrix resin that can be used include polyvinylidene fluoride, hexafluoropropylene (HFP), polytetrafluoroethylene, and copolymers thereof.

[0089] Examples of inorganic materials include metals, semiconductors, and oxides or nitrides thereof. In this case, examples of metals include aluminum and titanium, and examples of semiconductors include silicon and boron. It is preferable that the inorganic material is substantially non-conductive and has a large heat capacity. This is because a large heat capacity is useful as a heat sink when heat is generated by current, and makes it possible to further suppress thermal runaway of the battery 100. Examples of such inorganic materials include alumina (Al2O3), boehmite (alumina monohydrate), talc, boron nitride (BN), aluminum nitride (AlN), titanium dioxide (TiO2), silicon oxide (SiO2), and the like. x ) and other oxides or nitrides.

[0090] The particle size of the inorganic material is preferably in the range of 1 nm to 10 μm. If the particle size of the inorganic material is smaller than 1 nm, it will be difficult to obtain, and even if it is available, it will not be cost-effective. If the particle size of the inorganic material is larger than 10 μm, the distance between the electrodes will be large, and the amount of active material filled in the limited space will not be sufficient, resulting in low battery capacity.

[0091] The resin layer of the separator 33 can be formed, for example, by applying a slurry consisting of a matrix resin, a solvent, and an inorganic substance onto a substrate (porous membrane), passing the slurry through a bath of a poor solvent for the matrix resin and a good solvent for the above-mentioned solvent to cause phase separation, and then drying the slurry.

[0092] The puncture strength of the separator 33 is preferably in the range of 100 gf or more and 1000 gf or less, and more preferably in the range of 100 gf or more and 480 gf or less. If the puncture strength is low, a short circuit may occur, and if the puncture strength is high, the ionic conductivity decreases.

[0093] The air permeability of separator 33 is preferably in the range of 30 sec / 100 cc or more and 1000 sec / 100 cc or less. The air permeability of separator 33 is more preferably in the range of 30 sec / 100 cc or more and 680 sec / 100 cc or less. If the air permeability of separator 33 is low, a short circuit may occur, and if the air permeability is high, the ionic conductivity decreases.

[0094] The inorganic substance may be contained in the porous film serving as the substrate.

[0095] (electrolyte) The separator 33 is impregnated with an electrolytic solution, which is a liquid electrolyte. The electrolytic solution contains a solvent and an electrolyte salt dissolved in the solvent. To improve the characteristics of the battery 100, the electrolytic solution may contain known additives.

[0096] As the solvent, a cyclic carbonate such as ethylene carbonate or propylene carbonate can be used, and it is preferable to use either ethylene carbonate or propylene carbonate, or particularly a mixture of both, because in this case, the cycle characteristics can be improved.

[0097] Furthermore, it is preferable to use a mixture of the above-mentioned cyclic carbonate esters and chain carbonate esters such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, or methyl propyl carbonate as the solvent, because in this case, high ionic conductivity can be obtained.

[0098] In addition, it is preferable to contain 2,4-difluoroanisole or vinylene carbonate as the solvent. 2,4-Difluoroanisole can improve the discharge capacity, and vinylene carbonate can improve the cycle characteristics. Therefore, it is more preferable to use a mixture of 2,4-difluoroanisole and vinylene carbonate, as this can improve the discharge capacity and cycle characteristics.

[0099] Other examples of the solvent include butylene carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, methyl acetate, methyl propionate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropylnitrile, N,N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N,N-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, dimethyl sulfoxide, and trimethyl phosphate.

[0100] In addition, compounds in which at least some of the hydrogen atoms in these non-aqueous solvents have been substituted with fluorine may be preferable in some cases, since they may be able to improve the reversibility of the electrode reaction depending on the type of electrode to be combined with them.

[0101] Examples of electrolyte salts include lithium salts. One type of lithium salt may be used alone, or two or more types may be used in combination. Examples of lithium salts include LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiAlCl4, LiSiF6, LiCl, lithium difluoro[oxolato-O,O']borate, lithium bis(oxalate)borate, and LiBr. Among these, LiPF6 is preferred because it can provide high ionic conductivity and improve cycle characteristics.

[0102] [Battery operation] In the battery 100 having the above-described configuration, when charging is performed, for example, lithium ions are released from the positive electrode active material layer 31B and are absorbed into the negative electrode active material layer 32B via the electrolyte. When discharging is performed, for example, lithium ions are released from the negative electrode active material layer 32B and are absorbed into the positive electrode active material layer 31B via the electrolyte.

[0103] [Battery manufacturing method] An example of a method for manufacturing the above-described battery 100 will be described below.

[0104] First, a cathode material capable of doping and dedoping lithium, a conductive agent, and a binder are mixed to prepare a cathode mixture, and this cathode mixture is dispersed in a mixed solvent to form a cathode mixture slurry. Next, the cathode mixture slurry is applied to a cathode current collector 31A, dried, and then compression-molded to produce the cathode 31. Then, a cathode lead 36 is connected to the cathode current collector 31A by ultrasonic welding, spot welding, or the like.

[0105] A negative electrode material capable of doping and dedoping lithium is mixed with a binder to prepare a negative electrode mixture, which is then dispersed in a mixed solvent to form a negative electrode mixture slurry. The negative electrode mixture slurry is then applied to a negative electrode current collector 32A, dried, and then compression-molded to form the negative electrode 32. A negative electrode lead 37 is then connected to the negative electrode current collector 32A by ultrasonic welding, spot welding, or the like.

[0106] Next, the positive electrode 31 and the negative electrode 32 are stacked with a separator 33 interposed therebetween and wound a large number of times to produce the electrode assembly 30. The electrode assembly 30 is then sandwiched between a pair of insulating plates 34, 35 and housed inside the battery can 20. A positive electrode lead 36 is connected to the current interrupting member 3 of the safety mechanism 10, and a negative electrode lead 37 is connected to the battery can 20.

[0107] Next, an electrolyte solution is prepared by dissolving an electrolyte salt in a solvent, and then the electrolyte solution is poured into the battery can 20 to impregnate the separator 33. Next, a safety mechanism 10 is attached to the open end of the battery can 20 by crimping it via a gasket 11.

[0108] The above-described method completes the battery 100. A resin ring washer may be attached to the lid 1, or the entire battery 100 may be covered with a resin tube.

[0109] The present invention is not limited to the above-described embodiment, and various applications and modifications can be made within the scope of the present invention.

[0110] For example, in the battery 100 according to the embodiment described above, the current interrupting member 3 has a protrusion 3b for connecting to the pressure release member 2 and a flat plate portion 3a, and the pressure release member 2 has a flat plate shape. However, as shown in FIG. 9 , the pressure release member 2 may have a protrusion 2b for connecting to the current interrupting member 3 and a flat plate portion 2a, and the current interrupting member 3 may have a flat plate shape. In either case, the pressure release member 2 and the current interrupting member 3 are both thin and flat or approximately flat, allowing the battery safety mechanism 10 to be made thinner. This allows, for example, when the size of the battery 100 is fixed, the sizes of the positive electrode 31 and the negative electrode 32, etc., to be increased, thereby increasing the capacity of the battery 100.

[0111] Furthermore, in the battery 100 according to the embodiment described above, the pressure release member 2 has a flat plate shape, but may have a portion bent toward the current interrupting member 3, like the disk plate of the battery described in Patent Document 1. Similarly, the flat plate portion 3a of the current interrupting member 3, which is the portion other than the protruding portion 3b, has a flat plate shape, but may have a portion bent toward the electrode body, like the interrupting disk of the battery described in Patent Document 1. [Explanation of symbols]

[0112] 1 lid 1a Flat part of the lid 1b Lid protrusion 1c Lid drain hole 2 Pressure release member 2a Flat portion of pressure release member 2b Convex portion of pressure release member 3 Current interrupting devices 3a Flat part of current interrupting member 3b Convex portion of current interrupting member 3c hole 3d Groove in current interrupting member 4. Insulation layer 10 Battery safety mechanism 11 Gasket 20 Battery can 21 First Groove 22 Second Groove 30 Electrode body 31 Positive electrode 32 Negative electrode 33 Separator 34,35 Insulating plate 36 Positive lead 37 Negative lead 38 Center Pin 100 batteries

Claims

1. The lid and a pressure release member in contact with the lid, which deforms when the internal pressure of the battery increases to release gas inside the battery to the outside; a current interruption member that is disposed on the opposite side of the pressure release member from the lid and is connected to the pressure release member, and that interrupts current flowing to the pressure release member when the internal pressure of the battery increases; an insulating layer interposed between the pressure release member and the current interrupting member; Equipped with the pressure release member has at least one groove that is open to the current-blocking member side, between a position where the pressure release member and the current-blocking member are connected and a position where the pressure release member and the lid are in contact, in a direction perpendicular to a stacking direction of the lid, the pressure release member, the current-blocking member, and the insulating layer; the pressure release member has a plurality of the grooves; The grooves include a first groove and a second groove located outside the first groove, and the first groove and the second groove have different depths; The first groove is deeper than the second groove. A battery safety mechanism characterized by:

2. 2. The battery safety mechanism according to claim 1, wherein the minimum thickness of the pressure release member at the position where the groove is provided is 0.1 mm or more and 0.2 mm or less in cross-sectional view along the stacking direction.

3. 3. The battery safety mechanism according to claim 1, wherein the depth of the groove is 0.1 mm or more and 0.2 mm or less.

4. 3. The safety mechanism of a battery according to claim 1, wherein, in a cross-sectional view along the stacking direction, the minimum thickness of the pressure release member at the position where the first groove is provided is 0.1 mm or more and 0.19 mm or less, and the minimum thickness of the pressure release member at the position where the second groove is provided is 0.11 mm or more and 0.2 mm or less.

5. 3. The battery safety mechanism according to claim 1, wherein the depth of the first groove is 0.11 mm or more and 0.2 mm or less, and the depth of the second groove is 0.1 mm or more and 0.19 mm or less.

6. 3. The safety mechanism of a battery according to claim 1, wherein the second groove is located near an inner contact edge of the area where the lid and the pressure release member are in contact with each other.

7. 3. The battery safety mechanism according to claim 1, wherein the groove has a circular or arcuate shape when viewed in the stacking direction.

8. the current interrupting member has a protruding portion for connecting to the pressure release member and a flat portion having a flat plate shape, 3. The battery safety mechanism according to claim 1, wherein the pressure release member has a flat plate shape.

9. the pressure release member has a protrusion for connecting to the current interruption member and a flat plate portion having a flat plate shape, 3. The battery safety mechanism according to claim 1, wherein the current interrupting member has a flat plate shape.

10. 3. The safety mechanism of a battery according to claim 1, wherein the current-interrupting member has a groove that opens toward the pressure-release member, in a direction perpendicular to the stacking direction, between a position where the current-interrupting member and the pressure-release member are connected and a position where the current-interrupting member and the insulating layer are in contact.

11. 3. The safety mechanism of a battery according to claim 1, wherein the pressure release member is made of at least one of aluminum, titanium, platinum, and gold.

12. 3. The battery safety mechanism according to claim 1, wherein the current interrupting member is made of at least one of aluminum, titanium, platinum, and gold.

13. 3. The battery safety mechanism according to claim 1, wherein the insulating layer is an adhesive layer that bonds the pressure release member and the current interrupting member together.

14. an electrode assembly including a positive electrode, a negative electrode, and a separator provided between the positive electrode and the negative electrode; a battery can that accommodates the electrode assembly; a safety mechanism for the battery according to claim 1 or 2 attached to the battery can; A battery comprising:

15. 15. The battery according to claim 14, which is a cylindrical lithium ion secondary battery.

Images