Secondary battery

Abstract

The present invention provides a secondary battery in which a collector terminal does not melt and an external force acting on the collector terminal can be absorbed inside the collector terminal to suppress buckling deformation of a sealing body to which the collector terminal is coupled. A secondary battery (10) is provided with: a case main body (11) having an opening (111); a long sealing body (12) for sealing the opening; an electrode body (2) which is housed in the case main body and in which a positive electrode body (21) and a negative electrode body (22) are laminated with a separator (23) therebetween; and a positive and negative current collector terminal (4) having a base portion (41) joined to both end portions in the longitudinal direction of the sealing body with an insulating member (3) therebetween, a base adjacent portion (42) adjacent to and connected to the base portion and spaced apart from or in separable contact with the insulating member, and a wire portion (43) in which a wire upper end portion (43a) is connected to the base adjacent portion and a wire lower end portion (43b) is joined to the electrode body. The base adjacent portion or the upper end portion of the wire is provided with an easily deformable portion (44) which is formed so as to deform with respect to the base portion without melting and displace the lower end portion of the wire in the longitudinal direction of the sealing body.

Description

Technical Field

[0001] The disclosed technology relates to a secondary battery used in a hybrid vehicle, an electric vehicle, and the like. Background Art

[0002] In the past, in order to prevent excessive temperature rise caused by overcharging or overdischarging, a current interruption mechanism is sometimes provided in secondary batteries used in hybrid vehicles, electric vehicles, etc. For example, Patent Document 1 discloses a secondary battery having a fuse mechanism as a current interruption mechanism, wherein the fuse mechanism is provided with a cross-section reduction portion near the fastening portion of the sealing body of the collector terminal joined to the electrode body, and the cross-section reduction portion melts when the temperature rises with excessive current. However, in the above-mentioned current interruption mechanism, since the cross-section reduction portion of the collector terminal melts when the temperature rises, there is a problem that the secondary battery cannot be used again unless the collector terminal is replaced.

[0003] On the other hand, for example, Patent Document 2 discloses a temperature sensor mounting structure that contacts the upper surface of a battery cell (upper surface of a sealing body) to monitor excessive temperature rise of the battery cell. By installing the temperature sensor, it is possible to protect the battery cell while preventing excessive temperature rise of the battery cell to avoid melting of the collector terminal.

[0004] Patent Document 1: US / A1 / 2013 / 0004831

[0005] Patent Document 2: Japanese Patent Application Publication No. 2009-176601

[0006] It should be noted that, in the past, when the end of the electrode body (the non-coated part of the active material) was joined to the collector terminal, external force was applied to the collector terminal, resulting in deformation of the collector terminal. Moreover, due to the deformation of the collector terminal, the sealing body connected to the collector terminal at both ends in the long side direction sometimes had a warping deformation in which the central part was displaced in the vertical direction.

[0007] In this regard, by increasing the rigidity of the collector terminal, the deformation of the collector terminal due to external force can be reduced. However, even if the rigidity of the collector terminal is increased, since the rigidity of the sealing body is generally lower than the rigidity of the collector terminal, there is a problem that the external force acting on the collector terminal is transmitted to the sealing body combined with the collector terminal roughly unchanged, and the warping deformation of the sealing body cannot be fully suppressed. Summary of the invention

[0008] The disclosed technology has been made in view of the above problems, and an object of the present invention is to provide a secondary battery in which the collector terminal is not melted and external force acting on the collector terminal can be absorbed inside the collector terminal to suppress warping deformation of a sealing body connected with the collector terminal.

[0009] (1) One method of the disclosed technology for solving the above-mentioned problems is a secondary battery comprising: a shell body having an opening; a sealing body for sealing the above-mentioned opening, the length of which in the long-side direction is longer than the length in the short-side direction perpendicular to the long-side direction; an electrode body housed in the above-mentioned shell body, the positive electrode body and the negative electrode body being stacked with a separator sandwiched therebetween; and positive and negative current collecting terminals, comprising a base portion coupled to both ends of the above-mentioned sealing body in the long-side direction via an insulating member, a base adjacent portion adjacent to and connected to the above-mentioned base portion and detachably abutting against the above-mentioned insulating member, and a lead portion having an upper end portion of the lead connected to the above-mentioned base adjacent portion and a lower end portion of the lead joined to the above-mentioned electrode body, wherein the base adjacent portion or the above-mentioned upper end portion of the lead is provided with an easily deformable portion, the easily deformable portion being formed to deform relative to the above-mentioned base portion without melting so as to enable the lower end portion of the above-mentioned lead to be displaced in the long-side direction of the above-mentioned sealing body.

[0010] (2) According to the secondary battery described in (1), preferably, there is a sensor contact surface on the upper surface of the above-mentioned sealing body, and the sensor contact surface is formed to be able to contact with a temperature sensor that monitors the battery temperature. The easily deformable portion is formed to deform in the long side direction of the above-mentioned sealing body when the displacement amount in the up-down direction of the central part of the above-mentioned sealing body is within a prescribed reference value relative to the external force acting on the lower end part of the above-mentioned lead in the long side direction of the above-mentioned sealing body.

[0011] (3) According to the secondary battery described in (1), the easily deformable portion is preferably a thin-walled portion extending in a short-side direction of the sealing body at a predetermined cross section from the base adjacent portion and formed at a position eccentric in a plate thickness direction.

[0012] (4) According to the secondary battery described in (1), the easily deformable portion is preferably a bent portion extending in a predetermined cross section in a short-side direction of the sealing body at the base adjacent portion.

[0013] (5) According to the secondary battery described in (1), the easily deformable portion is preferably a reduced width portion cut from a widthwise end portion of the base adjacent portion at a position separated from the insulating member along a short side direction of the sealing body.

[0014] (6) The secondary battery according to any one of (1) to (4) preferably has a second easily deformable portion, which is a thin-walled portion or a bent portion extending from the upper end of the above-mentioned lead along the long side direction of the above-mentioned sealing body with a predetermined cross-section, or a width-reduced portion cut from the width direction end along the long side direction of the above-mentioned sealing body.

[0015] (7) According to the secondary battery described in (1), the easily deformable portion is preferably a reduced width portion cut into the upper end portion of the lead from the end in the width direction along the longitudinal direction of the sealing body.

[0016] (8) According to the secondary battery described in (1), the easily deformable portion is preferably a constricted portion cut into the upper end portion of the lead along the longitudinal direction and the lateral direction of the sealing body. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic cross-sectional view of a secondary battery according to one aspect of the present embodiment.

[0018] Figure 2 It is for Figure 1 FIG. 1 is a schematic block diagram of a temperature monitoring system for a secondary battery pack.

[0019] Figure 3 It means that Figure 1 The illustrated electrode assembly is a schematic perspective view of a state in which a positive electrode body and a negative electrode body are stacked and wound with a separator interposed therebetween.

[0020] Figure 4 yes Figure 1 AA section view shown.

[0021] Figure 5A yes Figure 1 FIG. 1 is an enlarged cross-sectional view of a portion B in the first embodiment of the secondary battery shown.

[0022] Figure 5B yes Figure 5A An enlarged cross-sectional view of a modified example.

[0023] Figure 5C yes Figure 5A The D1 view is shown.

[0024] Figure 5D yes Figure 5A The E1 view is shown.

[0025] Fig. 6A yes Figure 1 FIG. 1 is an enlarged cross-sectional view of a portion B in the second embodiment of the secondary battery shown.

[0026] Figure 6B yes Fig. 6AAn enlarged cross-sectional view of a modified example.

[0027] Figure 6C yes Fig. 6A The D2 view is shown.

[0028] Fig.6D yes Fig. 6A The E2 view is shown.

[0029] Fig. 7A yes Figure 1 An enlarged cross-sectional view of a portion B in the third embodiment of the secondary battery shown.

[0030] Figure 7B yes Fig. 7A An enlarged cross-sectional view of a modified example.

[0031] Figure 7C yes Fig. 7A The D3 view is shown.

[0032] Fig.7D yes Fig. 7A The E3 view is shown.

[0033] Fig. 8A yes Figure 1 An enlarged cross-sectional view of a portion B in a fourth embodiment of a secondary battery shown.

[0034] Figure 8B yes Fig. 8A The D4 view is shown.

[0035] Fig. 9A yes Figure 1 An enlarged cross-sectional view of a portion B in the fifth embodiment of the secondary battery shown.

[0036] Fig. 9B yes Fig. 9A The D5 view is shown.

[0037] Fig. 9C yes Figure 1 An enlarged perspective view of part B in the fifth embodiment of the secondary battery shown. DETAILED DESCRIPTION

[0038] <Overall description of this secondary battery>

[0039] Next, the overall structure of a secondary battery according to an embodiment of the above-disclosed technology will be described in detail with reference to the drawings. Figure 1 Schematic cross-sectional view of a secondary battery according to one aspect of the present embodiment is shown in FIG. Figure 2 Shown in the Figure 1 FIG. 1 is a schematic block diagram of a temperature monitoring system for a secondary battery pack. Figure 3 It is shown in Figure 1 The illustrated electrode assembly is a schematic perspective view showing a state in which a positive electrode assembly and a negative electrode assembly are stacked and wound with a separator interposed therebetween. Figure 4 Shown in Figure 1 The AA cross-sectional view shown in each figure. The X direction shown in each figure represents the long side direction of the sealing body, the Y direction represents the short side direction of the sealing body, and the Z direction represents the vertical direction of the shell. In addition, the Z direction may also represent the plate thickness direction of the base adjacent portion.

[0040] like Figure 1 to Figure 4 As shown, the secondary battery 10 involved in the embodiment of the disclosed technology includes a shell 1, an electrode body 2 and a collector terminal 4. Here, the shell 1 includes: a shell body 11 with a bottom square tube shape, having a rectangular opening 111; a long and flat sealing body 12, which seals the opening 111, and the length of the long side direction is longer than the length of the short side direction orthogonal to the long side direction. The shell body 11 and the sealing body 12 are both made of aluminum, but considering the necessity of improving the opening performance of the safety valve not shown in the figure, the sealing body 12 uses a material that is softer and easier to deform than the collector terminal 4.

[0041] In addition, in the opening portion 111 of the housing body 11, only the thin-walled portion 111T is formed on the inner wall on the short side. Therefore, both end portions 12R of the sealing body 12 in the long side direction (X direction) are supported by the step portion 111S formed at the lower end of the thin-walled portion 111T. However, in the opening portion 111 of the housing body 11, there is no thin-walled portion on the inner wall on the long side, and even if the central portion of the sealing body 12 is displaced (warped) in the up-down direction (Z direction), the displacement cannot be prevented.

[0042] In addition, the upper surface 121 of the sealing body 12 has a sensor contact surface 12S, which is formed so as to be contactable with the temperature sensor 5 that monitors the battery temperature. The temperature sensor 5 is, for example, Figure 2 The control system 100 is connected to the control system 100 shown in FIG. The control system 100 includes a battery pack 101 including a temperature sensor 5 , a temperature monitoring unit 102 , a battery control unit 103 , a vehicle control unit 104 , and a power control unit 105 connected to a power motor 106 .

[0043] The battery pack 101 includes a plurality of secondary batteries (battery cells) 10 connected thereto and a temperature sensor 5 for measuring the battery temperature of at least one of the secondary batteries 10. The battery pack 101 supplies the power required by the power motor 106 via the power control unit 105. The temperature sensor 5 is connected to the temperature monitoring unit 102. The temperature sensor 5 may be, for example, a thermistor, a thermocouple, or the like.

[0044] When the battery temperature measured by the temperature sensor 5 exceeds a prescribed management temperature (e.g., 60 to 80°C) set lower than the battery upper limit temperature (e.g., 100 to 120°C) of the secondary battery 10, the temperature monitoring unit 102 transmits an alarm signal to the battery control unit 103. The battery control unit 103 that receives the alarm signal transmits a current suppression instruction or a current cutoff instruction to the battery pack 101. In addition, the vehicle control unit 104 that receives the abnormal signal of the battery temperature from the battery control unit 103 controls the power motor 106 via the power control unit 105. Therefore, the secondary battery 10 is protected so that the battery temperature DJ does not exceed the prescribed battery upper limit temperature. Therefore, the secondary battery 10 does not need to be provided with a fuse mechanism in the battery as in Patent Document 1. Among them, the battery upper limit temperature is usually set to be below the heat resistance temperature of the electrode body 2 (e.g., the heat resistance temperature of the separator 23).

[0045] In addition, the electrode body 2 is stacked with a positive electrode body 21 and a negative electrode body 22 via a separator 23 and housed in the case body 11. The positive electrode body 21 and the negative electrode body 22 respectively have active material non-coating parts 211 and 221 on which the active material KT1 and KT2 are not coated at one end 21K1 and 22K1 of the metal foil 21K and 22K, and active material coating parts 212 and 222 on which the active material KT1 and KT2 are coated at the metal foil 21K and 22K. The active material non-coating part 211 of the positive electrode body 21 and the active material non-coating part 221 of the negative electrode body 22 are arranged on opposite sides in the long side direction (X direction) of the sealing body 12. The active material coating parts 212 and 222 are formed at the other end 21K2 and 22K2 and the middle part 21K3 and 22K3 of the metal foil 21K and 22K.

[0046] For example, in a lithium-ion secondary battery, the metal foil 21K of the positive electrode body 21 is made of aluminum foil, for example, and the active material KT1 applied thereto is made of lithium transition metal oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNiO2, etc.). In addition, the metal foil 22K of the negative electrode body 22 is, for example, copper foil, and the active material KT2 coated thereon can be, for example, graphite, hard carbon, soft carbon, etc. In addition, the separator 23 can be, for example, a porous sheet such as polypropylene or polyethylene. Among them, the electrolyte can use a known non-aqueous electrolyte.

[0047] In addition, the positive collector terminal 4A is made of aluminum, for example, and the negative collector terminal 4B is made of copper, for example. Generally, since the tensile strength of the positive collector terminal 4A made of aluminum is lower than that of the negative collector terminal 4B made of copper, and the conductivity of the positive collector terminal 4A is lower than that of the negative collector terminal 4B, in order to achieve uniformity of the strength and allowable current of the positive collector terminal 4A and the negative collector terminal 4B, the thickness of the positive collector terminal 4A is made larger than that of the negative collector terminal 4B. The positive and negative collector terminals 4 have a base portion 41, a base adjacent portion 42, and a lead portion 43 formed integrally, respectively.

[0048] In addition, the base portion 41 is combined with the back side of the two end portions 12R of the sealing body 12 in the long side direction (X direction) via the insulating member 3. In addition, the base adjacent portion 42 is adjacently connected to the base portion 41, and is separated from or detachably abutted against the insulating member 3. The lead portion 43 is bent from the base adjacent portion 42 to the lower direction (Z direction) of the shell at the position of the upper end portion 43a of the lead connected to the base adjacent portion 42 and located above the shell, and the metal foils 21K and 22K of the active material non-coated portions 211 and 221 of the electrode body 2 are welded and joined to the lower end portion 43b of the lead located below the shell in a foil collection state. When the electrode body 2 is welded to the lower end portion 43b of the lead, the lower end portion 43b of the lead slides relative to the metal foils 21K and 22K in the middle of the foil collection, and an external force that causes the lower end portion 43b of the lead to be displaced in the long side direction (X direction) of the sealing body 12 is easily generated.

[0049] The base portion 41 is connected to the external connection portion 45 located on the surface side of the sealing body 12, for example, by a rivet pin 46 or the like. An insulating member 3 serving as a seal is also sandwiched between the rivet pin 46 and the external connection portion 45 and the sealing body 12. For example, polyphenylene sulfide (PPS) resin can be used for the insulating member 3. When a plurality of the secondary batteries 10 are connected to form a battery pack 101, a bus bar (not shown) for connection is connected to the external connection portion 45.

[0050] In addition, the base adjacent portion 42 or the lead upper end portion 43a of the current collector terminal 4 is provided with an easily deformable portion 44, which is formed so as to deform with respect to the base portion 41 without melting so as to enable the lead lower end portion 43b to be displaced in the longitudinal direction (X direction) of the sealing body 12. That is, the easily deformable portion 44 is formed so as to deform in the longitudinal direction (X direction) of the sealing body 12 within a predetermined reference value (for example, about 10 to 20% of the plate thickness of the sealing body 12 or about 0.2 to 0.25 mm) when the displacement amount Q in the vertical direction (Z direction) at the center of the sealing body 12 with respect to the external force acting on the lead lower end portion 43b in the longitudinal direction (X direction) of the sealing body 12 is formed. Moreover, the easily deformable portion 44 is formed in a shape that does not melt at least when the battery temperature measured by the temperature sensor 5 is equal to or lower than a predetermined battery upper limit temperature.

[0051] When the electrode body 2 and the lower end portion 43b of the lead wire are welded, the easily deformable portion 44 is preferentially deformed by an external force that displaces the lower end portion 43b of the lead wire in the longitudinal direction (X direction) of the sealing body 12, and can absorb the external force to reduce the displacement of the base portion 41 of the collector terminal 4. Therefore, the warping deformation of the sealing body 12 caused by the base portion 41 being connected to the longitudinal end portions 12R of the sealing body 12 in the longitudinal direction and the central portion being displaced in the vertical direction (Z direction) can be effectively suppressed.

[0052] As a result, the temperature sensor 5 can make high-precision contact with the sensor contact surface 12S formed on the upper surface 121 of the sealing body 12, thereby improving the measurement accuracy of the temperature sensor 5. Furthermore, based on the result of the high-precision temperature measurement of the temperature sensor 5, the secondary battery 10 can be protected from overcharge or overdischarge without causing damage to the electrode body 2, the collector terminal 4, etc.

[0053] <First embodiment of the secondary battery>

[0054] Next, a first example of a secondary battery according to an embodiment of the above disclosed technology will be described in detail with reference to the drawings. Figure 5A Shown in Figure 1 FIG. 1 is an enlarged cross-sectional view of a portion B in the first embodiment of the secondary battery shown. Figure 5B Shown in Figure 5A An enlarged cross-sectional view of a modified example.

[0055] Figure 5C Shown in Figure 5A The D1 view is shown. Figure 5D Shown in Figure 5A The E1 view is shown.

[0056] In the secondary battery 10A of the first embodiment, as Figure 5A to Figure 5DAs shown, the easily deformable portion 44 is a thin-walled portion 44A that is extended in a predetermined cross section along the short side direction (Y direction) of the sealing body 12 and is formed at a position eccentric in the plate thickness direction (Z direction). The thin-walled portion 44A is formed on the plane side (here, the upper surface side) of the flat plate-shaped base adjacent portion 42 by forming a groove 44X with a cross section U-shaped relative to one plane (here, the lower surface). However, it is not necessary to be limited to this. For example, the thin-walled portion 44A can also be formed on the lower surface side by forming a groove with a cross section U-shaped relative to the upper surface of the flat plate-shaped base adjacent portion 42. In this way, since the thin-walled portion 44A is formed at a position that is eccentric in the plate thickness direction (Z direction) relative to the general portion of the base adjacent portion 42, the neutral line of the thin-walled portion 44A during the bending process is eccentric up and down relative to the neutral line of the general portion of the base adjacent portion 42 during the bending process. Even if an external force acts on the lower end portion 43b of the wire in parallel to the long side direction (X direction) of the sealing body 12, the base adjacent portion 42 on the wire portion 43 side can be simply bent in the up and down direction with the thin-walled portion 44A as the starting point.

[0057] In addition, it is preferable that the minimum plate thickness t1 of the thin-walled portion 44A is about 30 to 50% of the plate thickness t0 of the general portion. In this case, the base adjacent portion 42 is easily bent in the vertical direction relative to the base portion 41 with the thin-walled portion 44A as the starting point. Therefore, the amount of warping deformation of the sealing body 12 can be further reduced with respect to the external force acting on the lower end portion 43b of the lead in the long side direction (X direction) of the sealing body 12. In addition, the thin-walled portion 44A can also be formed by a groove with a V-shaped cross section or a W-shaped cross section.

[0058] because Figure 5A The base adjacent portion 42a shown is detachably abutted against the insulating member 3, so when the external force acting on the lower end portion 43b of the lead acts toward the outside of the battery in the long side direction (X direction) of the sealing body 12 (right direction in the drawing), the thin-walled portion 44A absorbs the external force by extending, and the amount of warping deformation of the sealing body 12 can be reduced. However, compared with the case where the external force acts toward the inside of the battery (left direction in the drawing), the reduction in the amount of warping deformation of the sealing body 12 is less.

[0059] Regarding this, Figure 5BThe base adjacent portion 42b of the modified example shown is formed in a step shape with respect to the base portion 41. Therefore, since the base adjacent portion 42b is separated from the insulating member 3, when the external force acting on the lower end portion 43b of the lead acts on the outer side of the battery (right direction in the drawing) in the long side direction (X direction) of the sealing body 12, the base adjacent portion 42b is easy to bend in the upward and downward direction starting from the thin-walled portion 44A, just like the case where the external force acts on the inner side of the battery (left direction in the drawing). Therefore, the amount of warping deformation of the sealing body 12 can be further reduced relative to the external force acting on the lower end portion 43b of the lead in the long side direction (X direction: battery inside and outside direction) of the sealing body 12.

[0060] The plate width dimension w3 of the long side direction (X direction) of the sealing body 12 in the lead portion 43 is formed to be smaller than the plate width dimension w1 of the short side direction (Y direction) of the sealing body 12 in the base portion 41. Therefore, when the lead portion 43 is joined to the electrode body 2, the lead portion 43 is easily deformed, but the deformation of the lead portion 43 can be prevented or reduced from propagating to the base portion 41 by the thin-walled portion 44A. As a result, the width dimension of the active material non-coated portion 211, 221 of the electrode body 2 welded to the lead portion 43 can be reduced, and the battery capacity per unit volume can be increased.

[0061] In addition, since the lead portion 43 is bent downwardly of the housing at the end portion in the width direction of the base adjacent portion 42, a notch portion 42c for bending the lead portion 43 is formed in the base adjacent portion 42. The plate width dimension w2 in the short side direction (Y direction) of the sealing body 12 in the thin-walled portion 44A is formed smaller than the plate width dimension w1 in the short side direction (Y direction) of the sealing body 12 in the base portion 41 due to the notch portion 42c. Accordingly, the thin-walled portion 44A is easily deformed, and the amount of warping deformation of the sealing body 12 can be further reduced with respect to the external force acting on the lead lower end portion 43b in the long side direction (X direction) of the sealing body 12.

[0062] <Second embodiment of the secondary battery>

[0063] Next, a second example of the secondary battery according to the embodiment of the above disclosed technology will be described in detail with reference to the drawings. Fig. 6A Shown in Figure 1 FIG. 1 is an enlarged cross-sectional view of a portion B in the second embodiment of the secondary battery shown. Figure 6B Shown in Fig. 6A An enlarged cross-sectional view of a modified example.

[0064] Figure 6C Shown in Fig. 6A The D2 view is shown. Fig.6D Shown in Fig. 6A The E2 view is shown.

[0065] In the secondary battery 10B of the second embodiment, as Figure 6A to Figure 6D As shown, the easily deformable portion 44 is a bent portion 44B extending in a predetermined cross section in the short-side direction (Y direction) of the sealing body 12 in the base adjacent portion 42 . Fig. 6A The curved portion 44B shown is a curved portion with a cross-section arc shape that protrudes from one plane (here, the lower surface) of the flat plate-shaped base adjacent portion 42 to the outward direction (here, the downward direction). However, this is not necessarily limited to this. For example, Figure 6B As shown, the curved portion 44B may be a curved portion with an arcuate cross section that protrudes upward from the upper surface of the flat plate-shaped base adjacent portion 42. In this case, the base adjacent portion 42b only needs to be stepped downward relative to the base portion 41.

[0066] In this way, since the bent portion 44B is formed at a position eccentric in the vertical direction (Z direction) with respect to the general part of the base adjacent portion 42, even when an external force acts on the lower end portion 43b of the lead in parallel to the long side direction (X direction) of the sealing body 12, the base adjacent portion 42 on the lead portion 43 side can be easily bent in the vertical direction with a small force starting from the bent portion 44B. In addition, the bent portion 44B expands and contracts in the long side direction (X direction), and the base adjacent portion 42 on the lead portion 43 side can be displaced in parallel to the long side direction (X direction) with a small force.

[0067] In addition, it is preferable that the minimum plate thickness t2 of the bent portion 44B is about 30 to 50% of the plate thickness t0 of the general portion of the base adjacent portion 42. In this case, the base adjacent portion 42 is easy to expand and contract in the horizontal direction (X direction) or bend in the vertical direction (Z direction) relative to the base portion 41 with the bent portion 44B as the starting point. Therefore, the amount of warping deformation of the sealing body 12 can be further reduced relative to the external force acting on the lower end portion 43b of the lead in the long side direction (X direction) of the sealing body 12. In addition, the bent portion 44B can also be formed into a waveform with a V-shaped cross section or a W-shaped cross section.

[0068] In addition, the plate width dimension w3 of the long side direction (X direction) of the sealing body 12 in the lead portion 43 is formed to be smaller than the plate width dimension w1 of the short side direction (Y direction) of the sealing body 12 in the base portion 41. Therefore, when the lead portion 43 is joined to the electrode body 2, the lead portion 43 is easily deformed, and the deformation of the lead portion 43 can be prevented or reduced from propagating to the base portion 41 by the bent portion 44B. As a result, the width dimension of the active material non-coated portion 211, 221 of the electrode body 2 welded to the lead portion 43 can be reduced, and the battery capacity per unit volume can be increased.

[0069] In addition, since the lead portion 43 is bent toward the bottom of the housing at the end portion in the width direction of the base adjacent portion 42, a cutout portion 42c for bending the lead portion 43 is formed in the base adjacent portion 42. The plate width dimension w2 in the short side direction (Y direction) of the sealing body 12 in the bent portion 44B is formed smaller than the plate width dimension w1 in the short side direction (Y direction) of the sealing body 12 in the base portion 41 due to the cutout portion 42c. Therefore, the bent portion 44B is easily deformed, and the amount of warping deformation of the sealing body 12 can be further reduced with respect to the external force acting on the lower end portion 43b of the lead in the long side direction (X direction) of the sealing body 12.

[0070] <Third embodiment of the secondary battery>

[0071] Next, a third example of the secondary battery according to the embodiment of the above disclosed technology will be described in detail with reference to the drawings. Fig. 7A Shown in Figure 1 An enlarged cross-sectional view of a portion B in the third embodiment of the secondary battery shown. Figure 7B Shown in Fig. 7A An enlarged cross-sectional view of a modified example.

[0072] Figure 7C Shown in Fig. 7A The D3 view is shown. Fig.7D Shown in Fig. 7A The E3 view is shown.

[0073] In the secondary battery 10C of the third embodiment, as FIG. 7A to FIG. 7D As shown, the easily deformable portion 44 is a reduced width portion 44C cut from the widthwise end portion 421 of the base adjacent portion 42 along the short side direction (Y direction) of the sealing body 12. The reduced width portion 44C is formed in the widthwise center portion by forming U-shaped cutout portions 44C1 from both widthwise end portions 421 of the flat base adjacent portion 42. Since the lead portion 43 is bent at the widthwise end portion of the base adjacent portion 42, the cutout portion 44C2 forming the reduced width portion 44C also serves as a cutout portion for bending the lead portion 43 in the base adjacent portion 42.

[0074] However, it is not necessary to be limited to the above-mentioned shape. For example, the width reduction portion 44C can also be formed on the width direction end side of the flat base adjacent portion 42 by forming a U-shaped cutout portion 44C1 from one width direction end 421 of the flat base adjacent portion 42. In this way, since the width reduction portion 44C is formed on the base adjacent portion 42, even if an external force acts on the lower end portion 43b of the wire in parallel to the long side direction (X direction) of the sealing body 12, the base adjacent portion 42 on the side of the wire portion 43 can be simply bent in the up-down direction (Z direction) or the short side direction (Y direction) of the sealing body 12 with a small force using the width reduction portion 44C as a starting point.

[0075] In addition, it is preferable that the minimum plate width dimension w2 of the reduced width portion 44C is about 20 to 50% of the plate width dimension w1 of the general portion of the base portion 41. In this case, the base adjacent portion 42 on the side of the lead portion 43 is easily bent relative to the base portion 41 in the vertical direction (Z direction) or the short side direction (Y direction) of the sealing body 12 with the reduced width portion 44C as a starting point. Therefore, the amount of warping deformation of the sealing body 12 can be further reduced with respect to the external force acting on the lower end portion 43b of the lead in the long side direction (X direction) of the sealing body 12. In addition, the reduced width portion 44C can also be formed by, for example, the cutout portions 44C1 and 44C2 having a V-shaped cross section.

[0076] because Fig. 7A The base adjacent portion 42a shown is detachably abutted against the insulating member 3, so when the external force acting on the lower end portion 43b of the lead acts toward the outer side of the battery (right direction in the drawing) in the long side direction (X direction) of the sealing body 12, the width reduction portion 44C absorbs the external force by extending, and the amount of warping deformation of the sealing body 12 can be reduced. However, compared with the case where the external force acts toward the inner side of the battery (left direction in the drawing), the reduction in the amount of warping deformation of the sealing body 12 is less.

[0077] Regarding this, Figure 7B The base adjacent portion 42b of the modified example shown is formed in a step-like shape downwardly relative to the base portion 41. Therefore, since the width reduction portion 44C of the easily deformable portion 44 is formed in the base adjacent portion 42b at a position separated from the insulating member 3, when the external force acting on the lower end portion 43b of the lead acts on the outer side of the battery (right direction in the drawing) in the long side direction (X direction) of the sealing body 12, the base adjacent portion 42b is easy to bend in the up-down direction (Z direction) starting from the width reduction portion 44C, just like the case where the external force acts on the inner side of the battery (left direction in the drawing). Therefore, the amount of warping deformation of the sealing body 12 can be further reduced relative to the external force acting on the lower end portion 43b of the lead in the long side direction (X direction: battery inside and outside direction) of the sealing body 12.

[0078] The plate width dimension w3 of the long side direction (X direction) of the sealing body 12 in the lead portion 43 is formed to be smaller than the plate width dimension w1 of the short side direction (Y direction) of the sealing body 12 in the base portion 41. Therefore, when the lead portion 43 is joined to the electrode body 2, the lead portion 43 is easily deformed, and the deformation of the lead portion 43 can be prevented or reduced from propagating to the base portion 41 by the width reduction portion 44C. As a result, the width dimension of the active material non-coated portion 211, 221 of the electrode body 2 welded to the lead portion 43 can be reduced, and the battery capacity per unit volume can be increased.

[0079] <Application examples of the first, second and third embodiments of the secondary battery>

[0080] Next, refer to Figures 5A to 7D The application examples of the first, second and third embodiments of the secondary battery involved in the embodiment of the above-mentioned disclosed technology are described in detail. The application examples are secondary batteries 10A1, 10A2, 10B1, 10B2, 10C1 and 10C2 in which the upper end portion 43a of the lead wire has a thin-walled portion 47A or a bent portion 47B extending along the long side direction (X direction) of the sealing body 12 with a predetermined cross section, or a width reduction portion 47C cut from the width direction end 431 along the long side direction (X direction) of the sealing body 12, that is, a second easily deformable portion 47.

[0081] Here, since the upper end portion 43a of the lead wire is provided with a thin-walled portion 47A or a bent portion 47B extending in a predetermined cross section along the long side direction (X direction) of the sealing body 12, or a width-reduced portion 47C cut from the width-direction end 431 along the long side direction (X direction) of the sealing body 12, i.e., the second easily deformable portion 47, when an external force acts on the lower end portion 43b of the lead wire of the collector terminal 4 in the short side direction (Y direction) of the sealing body 12, the second easily deformable portion 47 bends, and the lower end portion 43b of the lead wire can be displaced in the short side direction (Y direction) of the sealing body 12, thereby reducing the tilt displacement of the base portion 41 with respect to the short side direction (Y direction) of the sealing body 12. Therefore, in addition to reducing the warping deformation of the sealing body 12, the tilt deformation can also be reduced to further improve the measurement accuracy of the temperature sensor 5.

[0082] exist Figures 5A to 7DIn the embodiment, the second easily deformable portion 47 is formed in the same shape as the easily deformable portion 44, but it is not limited to this and can also be formed in a different shape from the easily deformable portion 44. Therefore, it is only necessary to select appropriately according to the size, physique, etc. of the secondary batteries 10A1, 10A2, 10B1, 10B2, 10C1, and 10C2. In addition, since the second easily deformable portion 47 is formed between the base adjacent portion 42 and the upper end of the electrode body 2, the separation distance required for the bending moment of the lower end portion 43b of the wire relative to the second easily deformable portion 47 can be ensured, and even if the external force during welding and joining with the electrode body 2 is small, the second easily deformable portion 47 can be simply deformed to effectively absorb the external force. In addition, since the second easily deformable portion 47 is formed between the base adjacent portion 42 and the upper end of the electrode body 2, the free space in the shell 1 can be effectively utilized.

[0083] <Fourth embodiment of the secondary battery>

[0084] Next, a fourth example of the secondary battery according to the embodiment of the above disclosed technology will be described in detail with reference to the drawings. Fig. 8A Shown in Figure 1 An enlarged cross-sectional view of a portion B in a fourth embodiment of a secondary battery shown. Figure 8B Shown in Fig. 8A The D4 view is shown.

[0085] In the secondary battery 10D of the fourth embodiment, as Fig. 8A , Figure 8B As shown in the figure, the easily deformable portion 44 is a width reduction portion 44D cut from the width direction end portion 431 along the long side direction (X direction) of the sealing body 12 at the upper end portion 43a of the wire. The width reduction portion 44D is formed in the width direction center portion by forming U-shaped cutout portions 44D1 and 44D2 from the width direction ends 431 of the flat wire portion 43. However, it is not necessary to be limited to the above shape. For example, the width reduction portion 44D may be formed on the width direction end side of the other side by forming a U-shaped cutout portion 44D1 from the width direction end portion 431 of the flat wire portion 43.

[0086] Since the reduced width portion 44D is formed at the lead upper end portion 43a, even when an external force acts on the lead lower end portion 43b in the long-side direction (X direction) and the short-side direction (Y direction) of the sealing body 12 due to the welding and joining of the lead lower end portion 43b and the electrode body 2, the lead lower end portion 43b can be simply bent in the long-side direction (X direction) or the short-side direction (Y direction) of the sealing body 12 with the reduced width portion 44D as a starting point. Therefore, in addition to reducing the warping deformation of the sealing body 12, the tilting deformation can also be reduced, and the measurement accuracy of the temperature sensor 5 can be further improved.

[0087] In addition, it is preferable that the minimum plate width dimension w2 of the reduced width portion 44D is about 20 to 50% of the plate width dimension w3 of the general portion of the lead portion 43. In this case, the lead lower end portion 43b is easily bent relative to the base portion 41 in the long side direction (X direction) or the short side direction (Y direction) of the sealing body 12 with the reduced width portion 44D as a starting point. Therefore, the warping deformation and tilting deformation of the sealing body 12 can be further reduced with respect to the external force acting on the lead lower end portion 43b in the long side direction (X direction) and the short side direction (Y direction) of the sealing body 12. In addition, the reduced width portion 44D can also be formed by, for example, V-shaped cutout portions 44D1 and 44D2.

[0088] <Fifth embodiment of the secondary battery>

[0089] Next, a fifth example of the secondary battery according to the embodiment of the above disclosed technology will be described in detail with reference to the drawings. Fig. 9A Shown in Figure 1 An enlarged cross-sectional view of a portion B in the fifth embodiment of the secondary battery shown. Fig. 9B Shown in Fig. 9A The D5 view is shown. Fig. 9C Shown in Figure 1 An enlarged perspective view of part B in the fifth embodiment of the secondary battery shown.

[0090] In the secondary battery 10E of the fifth embodiment, as Figures 9A to 9C As shown, the easily deformable portion 44 is a constricted portion 44E cut into the upper end portion 43a of the lead along the long side direction (X direction) and the short side direction (Y direction) of the sealing body 12. The constricted portion 44E is formed in the central portion in the width direction and the plate thickness direction by forming approximately U-shaped cutout portions 44E1 and 44E2 from both width direction ends 431 of the plate-shaped lead portion 43 and forming arc-shaped cutout portions 44E3 and 44E4 from both plate thickness direction ends 432. However, it is not necessary to be limited to the above-mentioned shape. For example, the constricted portion 44E may be formed by, for example, V-shaped cutout portions from both width direction ends 431 and both plate thickness direction ends 432, respectively.

[0091] In this way, since the constricted portion 44E is formed at the upper end portion 43a of the lead wire, when an external force acts on the lower end portion 43b of the lead wire in the long-side direction (X direction) and the short-side direction (Y direction) of the sealing body 12 along with the welding and joining of the lower end portion 43b of the lead wire and the electrode body 2, or when an external force acts on the lower end portion 43b of the lead wire in the torsion direction (W direction) of rotating the lower end portion 43b of the lead wire around the axis in the vertical direction (Z direction), the lower end portion 43b of the lead wire can be easily deformed in the long-side direction (X direction), the short-side direction (Y direction) or the torsion direction (W direction) of the sealing body 12 with the constricted portion 44E as the starting point. Therefore, in addition to reducing the warping deformation of the sealing body 12, the tilting deformation and the torsion deformation can also be reduced, and the measurement accuracy of the temperature sensor 5 can be further improved.

[0092] In addition, it is preferable that the minimum cross-sectional area s1 of the constricted portion 44E is about 20 to 50% of the cross-sectional area s0 of the general portion of the lead portion 43. In this case, the lead lower end portion 43b is easily deformed relative to the base portion 41 in the long side direction (X direction), short side direction (Y direction) or torsional direction (W direction) of the sealing body 12 with the constricted portion 44E as a starting point. Therefore, with respect to the external force acting on the lead lower end portion 43b in the long side direction (X direction), short side direction (Y direction) and torsional direction (W direction) of the sealing body 12, the warping deformation, tilting deformation and torsional deformation of the sealing body 12 can be further reduced.

[0093] <Modification>

[0094] The above detailed description of the present embodiment is merely a simple illustration and does not constitute any limitation on the disclosed technology. Therefore, the disclosed technology can be modified and altered in various ways without departing from the gist of the present invention. Figure 1 In the secondary battery 10 shown, the base portion 41 of the collector terminal 4 is connected to the external connection portion 45 located on the surface side of the sealing body 12, for example, by a rivet pin 46 or the like. An insulating component 3 that also serves as a seal is also sandwiched between the rivet pin 46 and the external connection portion 45 and the sealing body 12. However, it is not necessary to be limited to this. For example, it is also possible to have a structure in which the collector terminal 4 and the sealing body 12 are connected to the insulating component 3 by insert molding. In this case, the base portion 41 of the collector terminal 4 is inserted into the insulating component 3, and the base adjacent portion 42 is separated from the insulating component 3. Therefore, the various forms of the easily deformable portion 44 of the above-mentioned embodiments 1 to 5 can be formed on the base adjacent portion 42 separated from the insulating component 3 or the upper end portion 43a of the wire.

[0095] Description of reference numerals:

[0096] 1…housing; 2…electrode body; 3…insulating member; 4…collecting terminal; 5…temperature sensor; 10, 10A, 10B, 10C…secondary battery; 10D, 10E, 10A1…secondary battery; 10A2, 10B1, 10B2…secondary battery; 10C1, 10C2…secondary battery; 11…housing body; 12…sealing body; 12R…both ends in the long side direction; 12S…sensor contact surface; 21…positive electrode body; 22…negative electrode body ; 23…partition plate; 41…base portion; 42…base adjacent portion; 43…conductor portion; 43a…conductor upper end portion; 43b…conductor lower end portion; 44, 47…easily deformable portion; 44A, 47A…thin-walled portion; 44B, 47B…bent portion; 44C, 44D, 47C…width-reduced portion; 44E…narrowed neck portion; 111…opening portion; 121…upper surface; 421, 431…end portions in the width direction; DJ…battery temperature; Q…displacement.

Claims

1. A secondary battery, characterized in that: have: A shell body having an opening; A sealing body for sealing the opening, wherein the length of the long side is longer than the length of the short side orthogonal to the long side; The electrode body is accommodated in the shell body, and is formed by stacking a positive electrode body and a negative electrode body with a separator interposed therebetween; and The positive and negative current collecting terminals have a base portion connected to both ends of the sealing body in the longitudinal direction via an insulating member, a base adjacent portion adjacent to and connected to the base portion and separated from or detachably abutting against the insulating member, and a lead portion having an upper end portion of the lead connected to the base adjacent portion and a lower end portion of the lead joined to the electrode body. The base adjacent portion or the upper end portion of the lead wire is provided with an easily deformable portion formed to deform relative to the base portion without melting so as to allow the lower end portion of the lead wire to be displaced in the longitudinal direction of the sealing body.

2. The secondary battery according to claim 1, characterized in that: A sensor contact surface is provided on the upper surface of the sealing body, and the sensor contact surface is formed to be able to contact a temperature sensor that monitors the battery temperature. The easily deformable portion is formed to deform in the longitudinal direction of the sealing body when a vertical displacement amount of a central portion of the sealing body is within a predetermined reference value in response to an external force acting on the lower end portion of the lead wire in the longitudinal direction of the sealing body.

3. The secondary battery according to claim 1, characterized in that: The easily deformable portion is a thin-walled portion extending in a predetermined cross section in the short-side direction of the sealing body in the base adjacent portion and formed at a position eccentric in the plate thickness direction.

4. The secondary battery according to claim 1, characterized in that The easily deformable portion is a bent portion extending in a short-side direction of the sealing body at a predetermined cross section at the base adjacent portion.

5. The secondary battery according to claim 1, characterized in that: The easily deformable portion is a reduced width portion cut from a widthwise end portion of the base adjacent portion at a position separated from the insulating member along the short side direction of the sealing body.

6. The secondary battery according to any one of claims 1 to 5, characterized in that: A second easily deformable portion is provided, which is a thin-walled portion or a bent portion extending at a predetermined cross section along the longitudinal direction of the sealing body at the upper end of the lead, or a narrowed width portion cut from a widthwise end along the longitudinal direction of the sealing body.

7. The secondary battery according to claim 1, characterized in that: The easily deformable portion is a reduced width portion cut into the upper end portion of the lead wire from the end portion in the width direction along the longitudinal direction of the sealing body.

8. The secondary battery according to claim 1, characterized in that: The easily deformable portion is a constricted portion cut into the upper end portion of the lead along the longitudinal direction and the lateral direction of the sealing body.

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