Secondary battery

Abstract

To provide a highly safe secondary battery provided with a current interrupt mechanism capable of quickly interrupting currents as the battery temperature rises without waiting for the gas pressure in the battery to rise above a predetermined value when a short circuit or other defects occur in an electrode body.SOLUTION: A secondary battery 10 includes: a battery case 1; an electrode body 2 housed in the battery case; and a current collector terminal 4 including an outer terminal 41 inserted in a terminal through hole 121 of the battery case and fixed to the battery case via an insulating resin member 31 and an inner terminal 42 formed to be energized to the outer terminal and connected to the electrode body. The current collector terminal is provided with a current interrupt mechanism 4S configured such that when the battery temperature rises above a predetermined temperature, the outer terminal and the inner terminal are separated by the biasing force of a spring member 43 biasing the outer terminal or / and the inner terminal and brought into a de-energized state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Generally, when a sealed secondary battery is charged with a high voltage or a large current, gas is generated within the battery, which may cause an increase in the battery's internal pressure and temperature. For this reason, for example, Patent Document 1 discloses a nonaqueous electrolyte secondary battery in which the composition of the positive electrode active material and the components of the electrolyte are specified to increase the amount of gas generated during overcharge, thereby facilitating the activation of a pressure-activated current interrupt mechanism within the battery case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-64717 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above secondary battery, the current interruption mechanism does not operate unless the gas pressure inside the battery rises above a predetermined value, which poses a problem of delayed current interruption if, for example, the battery temperature rises suddenly due to a short circuit inside the electrode body.

[0005] The disclosed technology has been made in consideration of such problems, and aims to provide a highly safe secondary battery equipped with a current interruption mechanism that can quickly interrupt current as the battery temperature rises when a short circuit occurs within the electrode body, without waiting for the gas pressure within the battery to rise above a predetermined value. [Means for solving the problem]

[0006] (1) One aspect of the disclosed technology for solving the above problem is a secondary battery comprising: a battery case; an electrode assembly housed in the battery case; a current collecting terminal having an external terminal inserted into a terminal through-hole of the battery case and fixed to the battery case via an insulating resin member; and an internal terminal formed to be electrically conductive with the external terminal and connected to the electrode assembly, wherein the current collecting terminal is equipped with a current interruption mechanism that, when the battery temperature rises above a predetermined temperature, separates the external terminal and the internal terminal due to the biasing force of a spring member that biases the external terminal and / or the internal terminal, thereby bringing the current collecting terminal into a non-conductive state.

[0007] (2) In the secondary battery described in (1), it is preferable that when the insulating resin member melts or softens, the current-breaking mechanism moves the external terminal outward from the battery due to the spring force of the spring member, so that the external terminal and the internal terminal are brought into a non-conductive state.

[0008] (3) In the secondary battery described in (1), the external terminal is fixed to the battery case via a laminated insulating resin member in which a low-melting-point resin member having a melting point lower than that of the insulating resin member is sandwiched between the insulating resin members, and it is preferable that the current-breaking mechanism is configured such that when the low-melting-point resin member melts or softens, the external terminal moves outward from the battery due to the biasing force of the spring member, and the external terminal and the internal terminal are brought into a non-conductive state.

[0009] (4) In the secondary battery described in (1), it is preferable that the internal terminal is fixed to the battery case or the insulating resin member via a second low-melting point resin member having a melting point lower than that of the insulating resin member, and that the current-breaking mechanism is configured such that when the second low-melting point resin member melts or softens, the internal terminal moves toward the inside of the battery due to the biasing force of the spring member, and the external terminal and the internal terminal are brought into a non-conductive state.

[0010] (5) In the secondary battery described in (1), it is preferable that the internal terminal is joined to the external terminal by a low-melting-point joining material having a melting point lower than that of the insulating resin material, and that the current-breaking mechanism is configured such that when the low-melting-point joining material melts or softens, the internal terminal moves toward the inside of the battery due to the biasing force of the spring material, and the external terminal and the internal terminal are brought into a non-conductive state. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of a secondary battery according to one aspect of the present embodiment. [Figure 2] 2 is a schematic perspective view showing a state in the middle of winding up the positive electrode body and the negative electrode body of the electrode assembly shown in FIG. 1, with a separator sandwiched therebetween. FIG. [Figure 3A] 2 is an enlarged cross-sectional view of a portion A shown in FIG. 1, showing the current-breaking mechanism in the secondary battery according to the first embodiment. FIG. [Figure 3B] FIG. 3B is an enlarged cross-sectional view of the state in which the current interruption mechanism shown in FIG. 3A is activated. [Figure 4A] 2 is an enlarged cross-sectional view of a portion A shown in FIG. 1, illustrating a current-blocking mechanism in a secondary battery according to a second embodiment. [Figure 4B] FIG. 4B is an enlarged cross-sectional view of the state in which the current-blocking mechanism shown in FIG. 4A is activated. [Figure 5A] 1. FIG. 4 is an enlarged cross-sectional view of a portion A shown in FIG. 1, showing a current-breaking mechanism in a secondary battery according to a third embodiment. [Figure 5B] FIG. 5B is an enlarged cross-sectional view of the state in which the current interruption mechanism shown in FIG. 5A is activated. [Figure 6A] 1. FIG. 4 is an enlarged cross-sectional view of a portion A shown in FIG. 1, showing a current-blocking mechanism in a secondary battery according to a fourth embodiment. [Figure 6B] FIG. 6B is an enlarged cross-sectional view of the state in which the current interruption mechanism shown in FIG. 6A is activated. [Figure 7A] 1. FIG. 4 is an enlarged cross-sectional view of a portion A shown in FIG. 1, showing a current-breaking mechanism in a secondary battery according to a fifth embodiment. [Figure 7B] FIG. 7B is an enlarged cross-sectional view of the state in which the current interruption mechanism shown in FIG. 7A is activated. [Figure 8A]FIG. 10 is a schematic partial cross-sectional view of a secondary battery of a sixth example according to another aspect of the present embodiment. [Figure 8B] 8B is a schematic partial cross-sectional view of the state in which the current interruption mechanism shown in FIG. 8A is activated. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Description of this secondary battery> Next, the configuration of a secondary battery according to one aspect of an embodiment of the disclosed technology will be described in detail with reference to the drawings. Fig. 1 shows a schematic cross-sectional view of a secondary battery according to one aspect of this embodiment. Fig. 2 shows a schematic perspective view of the electrode assembly shown in Fig. 1 in the middle of being wound up by stacking the positive electrode body and the negative electrode body with a separator sandwiched therebetween. In Fig. 1, the X direction indicates the longitudinal direction of the battery case, the Y direction indicates the vertical direction of the battery case, and the Z direction indicates the width direction (short direction) of the battery case.

[0013] 1 and 2, the secondary battery 10 includes a battery case 1, an electrode assembly 2 housed in the battery case 1, a current collecting terminal 4 having an external terminal 41 inserted into a terminal through-hole 121 of the battery case 1 and fixed to the battery case 1 via an insulating resin member 31, and an internal terminal 42 formed to be electrically conductive with the external terminal 41 and connected to the electrode assembly 2. The current collecting terminal 4 also includes a current interruption mechanism 4S that, when the battery temperature rises to a predetermined temperature or higher, separates the external terminal 41 and the internal terminal 42 due to the biasing force of a spring member 43 that biases the external terminal 41 and / or the internal terminal 42, thereby bringing the current collecting terminal 4 into a non-conductive state.

[0014] In the present secondary battery 10, the current collecting terminal 4 is provided with a current interruption mechanism 4S that separates the external terminal 41 and the internal terminal 42 due to the biasing force of the spring member 43 that biases the external terminal 41 and / or the internal terminal 42, thereby establishing a non-conductive state, when the battery temperature rises above a predetermined temperature. Therefore, when the battery temperature rises suddenly due to a short circuit or the like within the electrode body 2, the external terminal 41 and the internal terminal 42 separate and establish a non-conductive state without waiting for the gas pressure within the secondary battery 10 to rise above a predetermined value. Therefore, current can be interrupted quickly as the temperature of the secondary battery 10 rises, and a highly safe secondary battery 10 can be provided.

[0015] 1, the battery case 1 includes a rectangular cylindrical case body 11 extending in the longitudinal direction (X direction), and a pair of lids 12 that seal openings 111 formed at both ends of the case body 11 in the longitudinal direction (X direction). A terminal through-hole 121 is formed in the middle of the lid 12 in the up-down direction (Y direction). External terminals 41, 41K are inserted into the terminal through-hole 121 and fixed to the lid 12 via an insulating resin member 31. The insulating resin member 31 can be made of, for example, polyphenylene sulfide (PPS) resin.

[0016] One of the lids 12 (the left side in FIG. 1: the negative electrode body 22 side) is fitted with a current-cutoff mechanism 4S that separates the external terminal 41 and the internal terminal 42 due to the biasing force of a spring member 43 that biases the external terminal 41 and the internal terminal 42, bringing them into a non-conductive state, when the battery temperature rises above a predetermined temperature. By providing the current-cutoff mechanism 4S on the negative electrode side current-cutoff terminal 4, which has low contact resistance, it is possible to reduce power loss at the terminal contact points.

[0017] Furthermore, a current collecting terminal 4 serving as a fixed terminal 4K to which an external terminal 41K and an internal terminal 42 are connected is attached to the other lid body 12 (right side in FIG. 1: positive electrode body 21 side). However, the other lid body 12 (right side in FIG. 1: positive electrode body 21 side) does not necessarily have to be limited to a fixed terminal 4K, and a current collecting terminal 4 equipped with a current interruption mechanism 4S may be attached, as with one lid body 12 (left side in FIG. 1: negative electrode body 22 side). By providing a current interruption mechanism 4S on both the negative electrode side and the positive electrode side current collecting terminals 4, it becomes possible to quickly interrupt the current no matter where a short circuit occurs within the electrode body 2.

[0018] The battery case 1 is not limited to the above configuration as long as the interior of the battery case 1 is watertight. For example, the battery case may include a cylindrical case body with a bottom and an opening at one end, and a lid that seals the opening. The battery case 1 also includes an inlet (not shown) for injecting an electrolyte solution and a safety valve (not shown) that can open when the pressure inside the battery case 1 rises above a predetermined pressure. The material of the battery case 1 is not particularly limited, but may be, for example, aluminum or stainless steel. When connecting multiple secondary batteries 10, a connecting bus bar (not shown) is connected to the external terminals 41, 41K.

[0019] 2, the electrode body 2 is formed by stacking a positive electrode body 21 and a negative electrode body 22 with a separator 23 sandwiched therebetween and winding them in a flat shape. The electrode body 2 may also be formed by stacking a sheet-like positive electrode body 21 and a negative electrode body 22 in a planar shape with a sheet-like separator 23 sandwiched therebetween. The positive electrode body 21 and the negative electrode body 22 have active material-coated portions 212 and 222 in which the active materials KT1 and KT2 are coated on the electrode foils 21K and 22K, respectively, and active material-uncoated portions 211 and 221 in which the active materials KT1 and KT2 are not coated on one end portions 21K1 and 22K1 of the electrode foils 21K and 22K.

[0020] The active material uncoated portion 211 of the positive electrode body 21 and the active material uncoated portion 221 of the negative electrode body 22 are arranged to face each other in the longitudinal direction (X direction). The active material coated portions 212, 222 are formed on the other end portions 21K2, 22K2 and middle portions 21K3, 22K3 of the electrode foils 21K, 22K. As shown in FIG. 1, the active material uncoated portion 221 of the negative electrode body 22 is electrically connected to the internal terminal 42 of the current collector terminal 4 equipped with a current interrupt mechanism 4S. The active material uncoated portion 211 of the positive electrode body 21 is electrically connected to the internal terminal 42 of the current collector terminal 4 serving as the fixed terminal 4K.

[0021] In a lithium ion secondary battery, which is an example of the secondary battery 10, the electrode foil 21K of the cathode body 21 is made of, for example, aluminum foil, and the active material KT1 applied thereto is, for example, lithium transition metal oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 The electrode foil 22K of the negative electrode body 22 may be made of, for example, copper foil, and the active material KT2 coated thereon may be made of, for example, graphite, hard carbon, soft carbon, or the like. The separator 23 may be made of, for example, a porous sheet of polypropylene resin or polyethylene resin. The electrolyte may be a known non-aqueous electrolyte. The positive electrode current collector terminal 4 is made of, for example, aluminum, and the negative electrode current collector terminal 4 is made of, for example, copper.

[0022] As described above, the secondary battery 10 only needs to include a current interruption mechanism 4S in the current collecting terminal 4. The current interruption mechanism 4S separates the external terminal 41 and the internal terminal 42 due to the biasing force of the spring member 43 that biases the external terminal 41 and / or the internal terminal 42, thereby establishing a non-conductive state, when the battery temperature rises above a predetermined temperature. Therefore, the secondary battery 10 can be configured in various ways depending on the configuration of the external terminal 41, the internal terminal 42, the spring member 43, etc. Representative examples of the secondary battery 10 in various ways will be described below, focusing on the current interruption mechanism 4S. In the description of each example, items common to those described above will be designated by the same reference numerals, and, as a rule, their description will be omitted.

[0023] (First Example) FIG. 3A shows an enlarged cross-sectional view of the current-breaking mechanism in the secondary battery of the first embodiment at portion A shown in FIG. 1 . FIG. 3B shows an enlarged cross-sectional view of the current-breaking mechanism shown in FIG. 3A in an activated state. As shown in FIGS. 3A and 3B , in the secondary battery 10 of the first embodiment, when the insulating resin member 31 melts or softens, the biasing force of the spring member 43 moves the external terminal 41 outward from the battery, thereby de-energizing the external terminal 41 and the internal terminal 42. Preferably, the portions where the external terminal 41 is attached to the insulating resin member 31 and the portions where the lid 12 is attached to the insulating resin member 31 are formed with annular roughened surfaces 411, 122 having an arithmetic mean roughness of 30 to 500 nm, for example, to ensure watertightness with the insulating resin member 31.

[0024] The current interruption mechanism 4S includes a compressed spring member 43 between the external terminal 41 and the internal terminal 42. The spring member 43 is formed of a conductive spring member. The conductive spring member 43 can be formed, for example, of a clad member in which a coil-shaped spring material is covered with a metal material (e.g., copper) having high conductivity. Here, the spring member 43 is bonded only to the external terminal 41. Therefore, as shown in FIG. 3B , when the external terminal 41 and the spring member 43 move together toward the outside of the battery and the spring member 43 separates from the internal terminal 42, the external terminal 41 and the internal terminal 42 are de-energized. Note that the spring member 43 may also be bonded only to the internal terminal 42. In this case, when the external terminal 41 moves independently toward the outside of the battery and the spring member 43 separates from the external terminal 41, the external terminal 41 and the internal terminal 42 are de-energized.

[0025] In this case, when the battery temperature rises to the melting point of the insulating resin member 31 (for example, about 290°C when the insulating resin member 31 is made of PPS resin) or a softening temperature close to that (for example, about 270°C to 280°C), the external terminal 41 and the internal terminal 42 are separated by the biasing force of the spring member 43, resulting in a non-conductive state. Furthermore, since the external terminal 41 moves in a direction away from the internal terminal 42 relative to the battery case 1 (toward the outside of the battery), there is no need to secure extra space within the battery case 1, and the volumetric efficiency of the secondary battery 10 can be improved. Therefore, the volumetric efficiency of the secondary battery 10 can be improved while quickly interrupting current as the temperature rises, and a highly safe secondary battery 10 can be provided.

[0026] Because the secondary battery 10 includes a compressed spring member 43 between the external terminal 41 and the internal terminal 42, it can be assembled, for example, using the following procedure. The external terminals 41 and 41K and the lid 12 are insert-molded and secured to the insulating resin member 31. The internal terminal 42 is then joined to the electrode assembly 2 by welding or other methods. The spring member 43 is then sandwiched between the external terminal 41 and the internal terminal 42, and the spring member 43 is temporarily secured in a compressed state using bolts or other fasteners. The electrode assembly 2 is then inserted into the case body 11 from the fixed terminal 4K side, and both lids 12 and the case body 11 are welded together to seal the case. Finally, the bolts or other fasteners temporarily securing the external terminal 41 and the internal terminal 42 on the current interruption mechanism 4S side are removed, and the external terminal 41K and the internal terminal 42 on the fixed terminal 4K side are connected with bolts or other fasteners. The secondary battery 10 can be assembled using the above procedures. Furthermore, when a bus bar is connected to the external terminal 41, the bus bar needs to be formed so as to be able to deform as the external terminal 41 moves outward from the battery.

[0027] (Second Example) 4A shows an enlarged cross-sectional view of the current interruption mechanism in the secondary battery of the second embodiment at portion A shown in FIG. 1 . FIG. 4B shows an enlarged cross-sectional view of the current interruption mechanism in the activated state shown in FIG. 4A . As shown in FIGS. 4A and 4B , in the secondary battery 10B of the second embodiment, the external terminal 41 is fixed to the battery case 1 via a laminated insulating resin member 3 in which a low-melting-point resin member 32, which has a lower melting point than the insulating resin member 31, is sandwiched between the insulating resin member 31. In addition, in the current interruption mechanism 4BS provided in the current collecting terminal 4B of the secondary battery 10B of the second embodiment, when the low-melting-point resin member 32 melts or softens, the biasing force of the spring member 43 moves the external terminal 41 outward from the battery, thereby de-energizing the external terminal 41 and the internal terminal 42.

[0028] The laminated insulating resin member 3 has a first insulating resin member 31 (31a) fixed to the lid 12 and a second insulating resin member 31 (31b) fixed to the external terminal 41, and an annular low-melting-point resin member 32 laminated to a predetermined thickness between them. The first insulating resin member 31 (31a) and the second insulating resin member 31 (31b) can be made of, for example, polyphenylene sulfide (PPS) resin, and the low-melting-point resin member 32 can be made of, for example, polypropylene (PP) resin.

[0029] In this case, when the battery temperature rises to the melting point of the low-melting-point resin member 32 (approximately 170°C when the low-melting-point resin member 32 is made of polypropylene (PP) resin) or its softening temperature (e.g., approximately 150°C to 160°C), as shown in FIG. 4B , the external terminal 41 fixed to the battery case 1 (lid 12) moves away from the internal terminal 42 (outside the battery) due to the biasing force of the spring member 43, thereby interrupting the battery current. Therefore, the battery current can be interrupted at a lower temperature without waiting for the battery temperature to rise to the melting point of the insulating resin members 31 (31a, 31b). Furthermore, in this case, since the external terminal 41 moves away from the internal terminal 42 (outside the battery) relative to the battery case 1, there is no need to secure extra space within the battery case 1, which can improve the volumetric efficiency of the secondary battery 10B.

[0030] Preferably, the portion where the external terminal 41 is fixed to the insulating resin member 31b and the portion where the lid 12 is fixed to the insulating resin member 31a are formed with annular roughened surfaces 411, 122 having an arithmetic mean roughness of 30 to 500 nm, for example, to ensure watertightness between the insulating resin members 31a, 31b. The current-breaking mechanism 4BS also includes a compressed spring member 43 between the external terminal 41 and the internal terminal 42. The spring member 43 is made of a conductive spring member 43. Because the compressed spring member 43 is interposed between the external terminal 41 and the internal terminal 42, the secondary battery 10B may be assembled, for example, using the same procedure as in the first embodiment.

[0031] (Third Example) 5A shows an enlarged cross-sectional view of the current interruption mechanism in the secondary battery of the third embodiment at part A shown in FIG. 1. FIG. 5B shows an enlarged cross-sectional view of the current interruption mechanism shown in FIG. 5A in an activated state. As shown in FIGS. 5A and 5B, in secondary battery 10C of the third embodiment, current interruption mechanism 4CS provided on current collector terminal 4C moves external terminal 41C outward from the battery due to the biasing force of spring member 43C when insulating resin member 31 melts or softens, thereby de-energizing external terminal 41C and internal terminal 42. Preferably, annular roughened surfaces 411, 122 having an arithmetic mean roughness of 30 to 500 nm are formed at the portions where external terminal 41C is fixed to insulating resin member 31 and where lid 12 is fixed to insulating resin member 31, respectively, to ensure watertightness with insulating resin member 31.

[0032] The current interruption mechanism 4CS includes a compressed spring member 43C between the external terminal 41C and the internal terminal 42. The spring member 43C is formed of a non-conductive spring member 43C. This non-conductive spring member 43C can be formed, for example, of a clad member in which a coil-shaped spring material is coated with an insulating material. Here, the spring member 43C is non-conductive, but this is not necessarily limited thereto. A conductive spring member may be used as long as an insulating sheet is interposed between the external terminal 41C or the internal terminal 42. Here, the spring member 43C is interposed between the external terminal 41C and the internal terminal 42, but this is not necessarily limited thereto. The spring member 43C may be interposed between the external terminal 41C and the lid 12. In this case, if the spring member 43C is a conductive spring member, an insulating sheet must be interposed between the external terminal 41C or the lid 12.

[0033] Furthermore, the external terminal 41C is formed with a hat-shaped cross section that has a space capable of accommodating the spring member 43C, and has a leg portion 412C that is joined to the internal terminal 42. The leg portion 412C and the internal terminal 42 are joined together with a metal joining member 44C that melts at a temperature lower than the melting point of the insulating resin member 31 (for example, if the insulating resin member 31 is PPS resin, a lead-free solder with a melting temperature of about 217°C or a leaded solder with a melting temperature of about 183°C, etc.). The metal joining member 44C may be an adhesive as long as it is a conductive joining member.

[0034] In this case, when the battery temperature rises to the melting point of the insulating resin member 31 (for example, about 290°C when the insulating resin member 31 is made of PPS resin) or a softening temperature close to that (for example, about 270°C to 280°C), the external terminal 41C and the internal terminal 42 are separated by the biasing force of the spring member 43, resulting in a non-conductive state. Furthermore, since the external terminal 41C moves in a direction away from the internal terminal 42 relative to the battery case 1 (toward the outside of the battery), there is no need to secure extra space within the battery case 1, and the volumetric efficiency of the secondary battery 10C can be improved. Therefore, the volumetric efficiency of the secondary battery 10C can be improved while quickly interrupting current as the temperature rises, thereby providing a highly safe secondary battery 10C.

[0035] Because the secondary battery 10C includes a compressed spring member 43C between the external terminal 41C and the internal terminal 42, it can be assembled, for example, using the following procedure. The external terminals 41C and 41K and the lid 12 are insert-molded and secured to the insulating resin member 31. The internal terminal 42 is then joined to the electrode assembly 2 by welding or other suitable means. The compressed spring member 43C is then inserted between the external terminal 41C and the internal terminal 42, and the leg portion 412C is joined to the internal terminal 42 with a metal joining member 44C. The electrode assembly 2 is then inserted into the case body 11 from the fixed terminal 4K side, and both lids 12 and the case body 11 are welded together to seal the case. Finally, the external terminal 41K on the fixed terminal 4K side is connected to the internal terminal 42 with a bolt or other suitable means. The secondary battery 10C can be assembled using the above procedure. Furthermore, when a bus bar is connected to the external terminal 41C, the bus bar needs to be formed so as to be able to deform as the external terminal 41C moves outward from the battery.

[0036] (Fourth Example) 6A shows an enlarged cross-sectional view of the current interruption mechanism in the secondary battery of the fourth embodiment at portion A shown in FIG. 1. FIG. 6B shows an enlarged cross-sectional view of the current interruption mechanism shown in FIG. 6A in an activated state. As shown in FIG. 6A, in the secondary battery 10D of the fourth embodiment, the internal terminal 42D is fixed to the battery case 1 or the insulating resin member 31 via a second low-melting-point resin member 33, which has a lower melting temperature than the insulating resin member 31. When the second low-melting-point resin member 33 melts or softens, the current interruption mechanism 4DS provided in the current collector terminal 4D of the secondary battery 10D of the fourth embodiment moves the internal terminal 42D toward the inside of the battery due to the biasing force of the spring member 43D, as shown in FIG. 6B, so that the external terminal 41 and the internal terminal 42D are de-energized. In addition, it is preferable that the fixing portion of the external terminal 41 to the insulating resin member 31 and the fixing portion of the lid body 12 to the insulating resin member 31 are formed with, for example, annular roughened surfaces 411, 122 having an arithmetic mean roughness of 30 to 500 nm to ensure watertightness with the insulating resin member 31.

[0037] This current interruption mechanism 4DS includes a compressed spring member 43D between the external terminal 41 and the internal terminal 42D. The spring member 43D is formed of a non-conductive spring member 43D. This non-conductive spring member 43D can be formed, for example, of a clad member in which a coil-shaped spring material is coated with an insulating material. Here, the spring member 43D is non-conductive, but this is not necessarily limited thereto. A conductive spring member may also be used as long as an insulating sheet is interposed between the external terminal 41 or the internal terminal 42D. Also, here, the spring member 43D is interposed between the external terminal 41 and the internal terminal 42D, but this is not necessarily limited thereto. The spring member 43D may also be interposed between the internal terminal 42D and the lid 12. In this case, if the spring member 43D is a conductive spring member, an insulating sheet must be interposed between the internal terminal 42D or the lid 12.

[0038] Furthermore, the internal terminal 42D is formed with a hat-shaped cross section that has a space capable of accommodating the spring member 43D, and includes a flange 421D that comes into contact with the external terminal 41. The flange 421D is fixed to the cover 12 and the insulating resin member 31 via a second low-melting-point resin member 33 that has a lower melting point than the insulating resin member 31. The insulating resin member 31 can be formed of, for example, polyphenylene sulfide (PPS) resin, and the second low-melting-point resin member 33 can be formed of, for example, polypropylene (PP) resin.

[0039] In this case, when the battery temperature rises to the melting point of the second low-melting-point resin member 33 (approximately 170°C when the second low-melting-point resin member 33 is formed of polypropylene (PP) resin) or a softening temperature close to that (for example, approximately 150°C to 160°C), as shown in FIG. 6B , the internal terminal 42D fixed to the lid body 12 and the insulating resin member 31 moves in a direction away from the external terminal 41 (inward of the battery) due to the biasing force of the spring member 43D, thereby interrupting the battery current. When the internal terminal 42D moves toward the inside of the battery, the active material-uncoated portion 221 of the negative electrode body 22 bends. Therefore, the battery current can be interrupted at a lower temperature without waiting for the battery temperature to rise to the melting point of the insulating resin member 31. In this case, the internal terminal 42D moves in a direction away from the external terminal 41 (toward the inside of the battery), and the external terminal 41 does not move relative to the battery case 1, so even if a bus bar or the like is connected to the external terminal 41, there is no need to form the bus bar or the like in a deformable manner.

[0040] Because the secondary battery 10D includes a compressed spring member 43D between the external terminal 41 and the internal terminal 42D, it can be assembled, for example, using the following procedure. The external terminals 41, 41K, and the lid 12 are insert-molded and secured to the insulating resin member 31. The internal terminal 42D is then joined to the electrode assembly 2 by welding or other methods. The compressed spring member 43D is then inserted between the external terminal 41 and the internal terminal 42D, and the external terminal 41 and the internal terminal 42D are temporarily secured in contact with each other. The internal terminal 42D and the lid 12 are then insert-molded and secured to the second low-melting-point resin member 33. The electrode assembly 2 is then inserted into the case body 11 from the fixed terminal 4K side, and both lids 12 and the case body 11 are welded together to seal the case. Finally, the external terminal 41K on the fixed terminal 4K side is connected to the internal terminal 42 with bolts or other methods. The secondary battery 10D can be assembled using the above procedures.

[0041] (Fifth Example) 7A shows an enlarged cross-sectional view of the current interruption mechanism in the secondary battery of the fifth embodiment at portion A shown in FIG. 1. FIG. 7B shows an enlarged cross-sectional view of the current interruption mechanism shown in FIG. 7A in an activated state. As shown in FIG. 7A, in the secondary battery 10E of the fifth embodiment, the internal terminal 42E is joined to the external terminal 41 by a low-melting-point joining member 44E having a melting point lower than that of the insulating resin member 31. When the low-melting-point joining member 44E melts or softens, the current interruption mechanism 4ES provided in the current collector terminal 4E of the secondary battery 10E of the fifth embodiment moves the internal terminal 42E toward the inside of the battery due to the biasing force of the spring member 43E, as shown in FIG. 7B, so that the external terminal 41 and the internal terminal 42E are brought into a non-conductive state. In addition, it is preferable that the fixing portion of the external terminal 41 to the insulating resin member 31 and the fixing portion of the lid body 12 to the insulating resin member 31 are formed with, for example, annular roughened surfaces 411, 122 having an arithmetic mean roughness of 30 to 500 nm to ensure watertightness with the insulating resin member 31.

[0042] The current interruption mechanism 4ES includes a compressed spring member 43E between the external terminal 41 and the internal terminal 42E. The spring member 43E is formed of a non-conductive spring member 43E. This non-conductive spring member 43E can be formed, for example, of a clad member in which a coil-shaped spring material is coated with an insulating material. Here, the spring member 43E is non-conductive, but this is not necessarily limited thereto. A conductive spring member may be used as long as an insulating sheet is interposed between the external terminal 41 or the internal terminal 42E. Here, the spring member 43E is interposed between the external terminal 41 and the internal terminal 42E, but this is not necessarily limited thereto. The spring member 43E may be interposed between the internal terminal 42E and the lid 12. In this case, if the spring member 43E is a conductive spring member, an insulating sheet must be interposed between the internal terminal 42E or the lid 12.

[0043] Furthermore, the internal terminal 42E is formed with a hat-shaped cross section that has a space capable of accommodating the spring member 43E, and includes a flange 421E that is joined to the external terminal 41. The flange 421E is joined with a low-melting-point joining member 44E that has a lower melting point than the insulating resin member 31 (for example, when the insulating resin member 31 is PPS resin, lead-free solder with a melting point of about 217°C or leaded solder with a melting point of about 183°C, etc.). The metal joining member 44C may be an adhesive as long as it is a conductive joining member.

[0044] In this case, when the battery temperature rises to the melting point of the low-melting-point joining member 44E (for example, if the low-melting-point joining member 44E is lead-free solder, the melting point of the low-melting-point joining member 44E is approximately 217°C) or its softening temperature (approximately 210°C to 215°C), the internal terminal 42E joined to the external terminal 41 moves in a direction away from the external terminal 41 (inward in the battery) due to the biasing force of the spring member 43E, thereby interrupting the battery current. When the internal terminal 42E moves inward in the battery, the active material-uncoated portion 221 of the negative electrode body 22 bends. Therefore, the battery current can be interrupted at a lower temperature without waiting for the battery temperature to rise to the melting point of the insulating resin member 31. Furthermore, in this case, since the internal terminal 42E moves in a direction away from the external terminal 41 (inward in the battery) and the external terminal 41 does not move relative to the battery case 1, even if a bus bar or the like is connected to the external terminal 41, there is no need to form the bus bar or the like to be deformable.

[0045] Since the secondary battery 10E has a compressed spring member 43E interposed between the external terminal 41 and the internal terminal 42E, it can be assembled, for example, using the following procedure. The external terminals 41, 41K, and the lid 12 are insert-molded and fixed to the insulating resin member 31. The internal terminal 42E is then joined to the electrode assembly 2 by welding or the like. Then, the compressed spring member 43E is inserted between the external terminal 41 and the internal terminal 42E, and the external terminal 41 and the internal terminal 42E are joined with a low-melting-point joining member 44E. Then, the electrode assembly 2 is inserted into the case body 11 from the fixed terminal 4K side, and both lids 12 and the case body 11 are welded and sealed. Finally, the external terminal 41K on the fixed terminal 4K side and the internal terminal 42 are connected with bolts or the like. The secondary battery 10E can be assembled using the above procedure.

[0046] (Sixth Example) 8A shows a schematic partial cross-sectional view of a secondary battery according to a sixth embodiment of the present invention. FIG. 8B shows a schematic partial cross-sectional view of the battery in a state where the current-breaking mechanism shown in FIG. 8A is activated. In FIG. 8A, the X direction indicates the longitudinal direction of the battery case, the Y direction indicates the vertical direction of the battery case, and the Z direction indicates the width (short-side direction) of the battery case. As shown in FIGS. 8A and 8B, a secondary battery 10F according to the sixth embodiment includes a battery case 1F, an electrode assembly 2 housed in the battery case 1F (a case body 11F having an opening 111F at one end), and a current collecting terminal 4F having an external terminal 41F inserted through a terminal through-hole 121 of the battery case 1F (a lid 12F) and fixed to the battery case 1F (a lid 12F) via an insulating resin member 31F, and an internal terminal 42F formed to be electrically conductive with the external terminal 41F and connected to the electrode assembly 2. In addition, the collector terminal 4F is equipped with a current interruption mechanism 4FS that, when the battery temperature rises above a predetermined temperature, separates the external terminal 41F and the internal terminal 42F due to the biasing force of a spring member 43F that biases the internal terminal 42F, thereby establishing a non-conductive state.

[0047] The internal terminal 42F is joined to the external terminal 41F by a low-melting-point joining member 44F that has a melting point lower than that of the insulating resin member 31F. When the low-melting-point joining member 44F melts or softens, the current-breaking mechanism 4FS moves the internal terminal 42F toward the inside of the battery due to the biasing force of the spring member 43F, as shown in Fig. 8B, and the external terminal 41F and the internal terminal 42F are separated, resulting in a non-conductive state. Preferably, the portion where the external terminal 41F is fixed to the insulating resin member 31F and the portion where the lid 12F is fixed to the insulating resin member 31F are formed with annular roughened surfaces 411, 122 having an arithmetic mean roughness of 30 to 500 nm, for example, to ensure watertightness with the insulating resin member 31F.

[0048] This current-breaking mechanism 4FS includes a tension spring member 43F between the battery case 1F (case body 11F) and the internal terminal 42F. The spring member 43F is formed of a non-conductive spring member 43F. This non-conductive spring member 43F can be formed, for example, of a clad member in which a coil-shaped spring material is covered with an insulating material. Here, the spring member 43F is non-conductive, but this is not necessarily limited to this. If the engagement pins 45, 46 that engage the spring member 43F with the battery case 1F (case body 11F) or the internal terminal 42F are insulating pins, the spring member 43F may be a conductive spring member.

[0049] The internal terminals 42F are joined with a low-melting-point joining member 44F having a lower melting point than the insulating resin member 31F (for example, if the insulating resin member 31F is PPS resin, a lead-free solder having a melting point of about 217°C or a leaded solder having a melting point of about 183°C). The low-melting-point joining member 44F may be an adhesive as long as it is a conductive joining member. Here, the lower end of the external terminal 41F and the upper end of the internal terminal 42F are surrounded by a low-melting-point resin member 33F (for example, PP resin) having a melting point lower than that of the low-melting-point joining member 44F. Note that the low-melting-point resin member 33F is useful for protecting the joint between the external terminal 41F and the internal terminal 42F, but is not necessarily required.

[0050] In this case, when the battery temperature rises to the melting point of the low-melting-point joining member 44F (for example, if the low-melting-point joining member 44F is lead-free solder, the melting point is approximately 217°C) or its softening temperature (approximately 210°C to 215°C), the internal terminal 42F joined to the external terminal 41F moves away from the external terminal 41F (inward in the battery) due to the biasing force of the spring member 43F, thereby interrupting the battery current. Therefore, the battery current can be interrupted at a lower temperature without waiting for the battery temperature to rise to the melting point of the insulating resin member 31F. Furthermore, in this case, since the internal terminal 42F moves away from the external terminal 41F (inward in the battery) and the external terminal 41F does not move relative to the battery case 1F, even if a bus bar or the like is connected to the external terminal 41F, there is no need to form the bus bar or the like to be deformable.

[0051] The secondary battery 10F includes a tension spring member 43F between the battery case 1F (case body 11F) and the internal terminal 42F, and can be assembled, for example, using the following procedure: The external terminal 41 and the internal terminal 42E are joined using a low-melting-point joining member 44F. The external terminal 41F, the internal terminal 42F, and the lid 12F are insert-molded to be fixed to the insulating resin member 31F. If necessary, after the insulating resin member 31F has solidified, they are insert-molded to be fixed to the low-melting-point resin member 33F. The internal terminal 42F and the electrode assembly 2 are joined by welding or the like. Then, while the spring member 43F is engaged with the case body 11F and the internal terminal 42F, the electrode assembly 2 is inserted into the case body 11F, and the lid 12F and the case body 11F are welded to seal the battery. The secondary battery 10F can be assembled using the above procedure.

[0052] <Modification> The present embodiment described in detail above is merely an example and does not limit the disclosed technology in any way. Therefore, the disclosed technology can be improved and modified in various ways without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0053] 1 Battery case 2 Electrode body 3. Insulating resin material 4 Current collector terminal 4S, 4BS, 4CS, 4DS current cutoff mechanism 4ES, 4FS current interruption mechanism 10, 10B, 10C, 10D secondary battery 10E, 10F secondary battery 31, 31F insulating resin material 32 Low-melting-point resin materials 33 Second low-melting-point resin member 41, 41C, 41F external terminals 42, 42D, 42E, 42F internal terminals 43, 43C, 43D, 43E Spring members 43F Spring material 44E, 44F Low melting point joining material 121 Terminal through hole

Claims

1. A battery case and an electrode assembly housed in the battery case; a current collecting terminal including an external terminal inserted into a terminal through-hole of the battery case and fixed to the battery case via an insulating resin member, and an internal terminal formed to be electrically conductive with the external terminal and connected to the electrode body, The current collecting terminal is provided with a current interruption mechanism that, when the battery temperature rises above a predetermined temperature, separates the external terminal and the internal terminal by the biasing force of a spring member that biases the external terminal and / or the internal terminal, thereby bringing the current collecting terminal into a non-conductive state. Secondary battery.

2. 2. The secondary battery according to claim 1, When the insulating resin member melts or softens, the current interruption mechanism moves the external terminal toward the outside of the battery due to the biasing force of the spring member, and the external terminal and the internal terminal are brought into a non-conductive state. Secondary battery.

3. 2. The secondary battery according to claim 1, the external terminals are fixed to the battery case via a laminated insulating resin member in which a low-melting-point resin member having a melting point lower than that of the insulating resin member is sandwiched between the insulating resin members, When the low-melting-point resin member melts or softens, the current-breaking mechanism moves the external terminal toward the outside of the battery due to the biasing force of the spring member, and the external terminal and the internal terminal are brought into a non-conductive state. Secondary battery.

4. 2. The secondary battery according to claim 1, the internal terminal is fixed to the battery case or the insulating resin member via a second low-melting-point resin member having a melting point lower than that of the insulating resin member; When the second low-melting-point resin member melts or softens, the current-breaking mechanism moves the internal terminal toward the inside of the battery due to the biasing force of the spring member, and the external terminal and the internal terminal are brought into a non-conductive state. Secondary battery.

5. 2. The secondary battery according to claim 1, the internal terminal is joined to the external terminal by a low-melting-point joining material having a melting point lower than that of the insulating resin material; When the low-melting-point bonding member melts or softens, the current-breaking mechanism moves the internal terminal toward the inside of the battery due to the biasing force of the spring member, and the external terminal and the internal terminal are brought into a non-conductive state. Secondary battery.

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