JPWO2013046349A1 - Square battery - Google Patents

Abstract

The present invention provides a prismatic battery 1 that can be used for an automobile, for example, when an external force is applied to the power generation element group 6 due to vibration, impact, collision, or the like, to prevent the power generation element group 6 from being crushed and to prevent occurrence of a short circuit or the like. It is an issue. The rectangular battery 1 of the present invention includes a flat power generation element group 6 in which a positive electrode sheet 11 and a negative electrode sheet 12 are overlapped with a separator 13 interposed therebetween and wound around an axis 14, and a battery can that houses the power generation element group 6 2 has a pair of reinforcing members 51 that extend from the power generation element group 6 to the outer side in the winding axis direction by extending the shaft core 14 to both sides in the winding axis direction of the shaft core 14. Yes.

Description

  The present invention relates to a prismatic battery.

  A flat power generation element group is produced by laminating and winding a sheet-like positive electrode and negative electrode with a separator interposed therebetween, and this flat power generation element group is a rectangular metal or resin filled with an electrolyte. 2. Description of the Related Art Lithium ion secondary batteries provided with a conductive member that is housed in a sealed container made of metal and that conducts electricity to the outside connected to both electrodes of a power generation element group are widely known.

  Lithium ion secondary batteries are mainly used in small electronic devices such as notebook computers and mobile phones, but because they have characteristics such as high output, high capacity and light weight compared to other types of secondary batteries, It is also used for hybrid cars or electric cars. It is necessary to consider that a lithium ion secondary battery mounted on an automobile may cause an external force to be crushed by a collision in addition to vibration and impact.

  Patent Document 1 discloses a structure of a prismatic battery that fixes a power generation element group to a battery can by compressing an elastic member interposed between the conductive member and the battery can in terms of impact resistance and vibration resistance. ing.

JP 2011-108507 A

  In the case of a square battery, when an external force is applied to the power generation element group due to vibration, impact, collision, or the like, the power generation element group may be collapsed and cause a problem such as a short circuit.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a prismatic battery capable of preventing the power generation element group of the prismatic battery from being crushed and preventing the occurrence of a short circuit or the like.

  The prismatic battery of the present invention that solves the above problems includes a flat power generation element group in which a positive electrode sheet and a negative electrode sheet are stacked with a separator interposed therebetween and wound around an axis, and a battery can that houses the power generation element group, The prismatic battery has a pair of reinforcing members that extend on both sides in the winding axis direction of the shaft core and project outward in the winding axis direction from the power generation element group.

  According to the present invention, when an external force acts in the winding axis direction of the power generation element group and the power generation element group moves in the winding axis direction in the battery can, the reinforcing member is brought into contact with the side wall portion of the battery container. And the deformation | transformation of the winding-axis direction edge part of an electric power generation element group can be prevented. Therefore, it is possible to suppress the occurrence of a short circuit due to the deformation of the power generation element group and improve the strength of the rectangular battery. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is an external perspective view of a lithium ion secondary battery according to an embodiment. The disassembled perspective view of the lithium ion secondary battery shown in FIG. The longitudinal cross-sectional view explaining the internal structure of the lithium ion secondary battery shown in FIG. The perspective view which shows the electric power generation element group after winding. The perspective view which shows the state before winding an electric power generation element group. The perspective view explaining the structure of an axial center. The perspective view which expands the principal part of an axial center and shows one part in a cross section. FIG. 2 is a cross-sectional perspective view taken along line AA in FIG. 1. The figure which shows the engaging part of a reinforcement member and a flat shaft core. The perspective view explaining an example of the composition of a reinforcing member. The perspective view explaining an example of the composition of a reinforcing member. The perspective view explaining an example of the composition of a reinforcing member. The figure explaining the method of engaging a reinforcement member with an electric power generation element group. Sectional drawing explaining the process of dividing the metal foil lamination | stacking part of an electric power generation element group into two in the thickness direction of an electric power generation element group, and forming a pair of connection part. Sectional drawing explaining the process of joining the connection part of an electric power generation element group to a current collection terminal. Sectional drawing explaining the process of engaging a reinforcement member with a flat shaft core. The perspective view explaining the other structure of a reinforcement member. The longitudinal cross-sectional view which shows the internal structure of the lithium ion secondary battery using the reinforcement member shown in FIG. The figure which shows the engaging part of the reinforcement member shown in FIG. 11, and an axial center. The perspective view explaining the other structure of a reinforcement member. The longitudinal cross-sectional view which shows the internal structure of the lithium ion secondary battery using the reinforcement member shown in FIG. The perspective view explaining the other structure of a reinforcement member. The longitudinal cross-sectional view which shows the internal structure of the lithium ion secondary battery using the reinforcement member shown in FIG. The figure explaining the method of engaging the reinforcement member shown in FIG. 16 with an electric power generation element group.

  Hereinafter, an embodiment in which a prismatic battery of the present invention is applied to a lithium ion secondary battery for a hybrid vehicle will be described with reference to the drawings.

  As shown in FIGS. 1 to 3, the lithium ion secondary battery 1 has a substantially rectangular (rectangular) appearance, and is a rectangular and bottomed metal (in this example, aluminum alloy) battery can 2. The battery lid 2 has a flat metal (in this example, aluminum alloy) battery lid 3 whose contour matches the opening of the battery can 2.

  The battery can 2 is formed by deep drawing, and includes a rectangular bottom wall portion PB, a pair of wide surface wall portions PW that rise upward from a pair of long sides of the bottom wall portion PB, and a bottom wall. It has one narrow side wall part PN that rises upward from a pair of short sides of the part PB.

  The battery lid 3 is joined to the inner periphery of the opening of the battery can 2 by laser (beam) welding, and the opening of the battery can 2 is sealed. The battery lid 3 is provided with a gas discharge valve 41 for cleaving at a preset pressure when the battery internal pressure rises and releasing the gas to the outside. The gas discharge valve 41 is a thin film member made of substantially the same metal material as the battery lid 3 and is joined to the battery lid 3 by laser welding or the like. In addition, the battery lid 3 is provided with a liquid injection port 42 for injecting an electrolytic solution into the battery can 2 after sealing the opening of the battery can 2. The liquid injection port 42 is sealed by a liquid injection plug 43 after injecting the electrolytic solution.

  A flat power generation element group 6, an electrolyte, and the like are accommodated in an internal space formed by the battery can 2 and the battery lid 3 of the lithium ion secondary battery 1. In addition, the lithium ion secondary battery 1 of this embodiment is neutral in which the battery can 2 and the battery cover 3 do not have polarity.

  The battery lid 3 is provided with a positive electrode terminal 21 and a negative electrode terminal 31. The positive electrode terminal 21 and the negative electrode terminal 31 are disposed at positions separated from each other on one side and the other side in the longitudinal direction of the battery lid 3. For example, as shown in FIG. 2, the positive electrode terminal 21 and the negative electrode terminal 31 are connected to the external terminals 22 and 32 arranged on the outside of the battery lid 3 and from the inside of the battery lid 3 toward the bottom wall portion PB in the battery can 2. Current collector terminals 24, 34 extending and connected to the power generation element group 6, and connection terminals 23 penetrating the battery lid 3 and electrically connecting the external terminals 22, 32 and the current collector terminals 24, 34. , 33.

  The positive terminal 21 is made of an aluminum alloy, and the negative terminal 31 is made of a copper alloy. The positive electrode terminal 21 and the negative electrode terminal 31 are electrically insulated from the battery lid 3 with the insulating member 20 interposed between them.

  The positive electrode terminal 21 and the negative electrode terminal 31 are fixed to the battery lid 3 to form a lid assembly. Between the current collecting terminal 24 of the positive electrode terminal 21 and the current collecting terminal 34 of the negative electrode terminal 31, the power generation element group 6 is It is inserted from one arc portion and integrated by joining or the like to form a power generation element assembly. Then, a pair of reinforcing members 51 and 51, which will be described later, are attached to both ends of the power generation element group 6 in the winding axis direction.

  The current collecting terminal 24 of the positive electrode terminal 21 is bent at both ends of the flat base portion 24 </ b> A (see FIG. 3) and the base portion 24 </ b> A arranged in parallel along the lower surface of the battery lid 3. A pair of current collecting connection pieces 24 </ b> B (see FIG. 2) that are spaced apart in the short side direction and face each other and extend toward the bottom wall portion PB of the battery can 2 are provided. The pair of current collecting connection pieces 24 </ b> B has a substantially C shape when viewed from above the battery can 2, and is inclined so that the distance between the connection pieces becomes narrower toward the center side in the long side direction of the battery lid 3. (See, for example, FIG. 10A).

  Similarly, the current collecting terminal 34 of the negative electrode terminal 31 is bent at both ends of the flat base 34A (see FIG. 3) arranged in parallel along the lower surface of the battery lid 3 and the base 34A. A pair of current collecting connection pieces 34 </ b> B (see FIG. 2) that are spaced apart from each other in the short side direction of the lid 3 and face each other and extend toward the bottom wall portion PB of the battery can 2. The pair of current collecting connection pieces 34 </ b> B has a substantially C shape when viewed from above the battery can 2, and is inclined so that the interval between the connection pieces becomes narrower toward the center side in the long side direction of the battery lid 3. (See, for example, FIG. 10A).

  The pair of current collecting connection pieces 24B on the positive electrode side are arranged to face the outside in the thickness direction of the power generation element group 6 at the end on the positive electrode side of the power generation element group 6, and each inner surface of the pair of current collection connection pieces 24B. Is joined to the outer surface of the positive electrode metal foil laminate portion 11c of the power generation element group 6 to be described later. The pair of current collecting connection pieces 34B on the negative electrode side are arranged to face the outer side in the flat thickness direction of the power generation element group 6 at the end on the negative electrode side of the power generation element group 6, respectively. The inner surface is joined to the outer surface of the negative electrode metal foil laminate 12c of the power generation element group 6 described later.

  4A and 4B are diagrams for explaining the configuration of the power generation element group. FIG. 4A shows the state of the power generation element group 6 after winding, and FIG. 4B shows the state before winding the power generation element group. Is shown.

  As shown in FIG. 4B, the power generation element group 6 is formed by winding around a plate-shaped shaft core 14 with a separator 13 interposed between the positive electrode sheet 11 and the negative electrode sheet 12. The power generation element group 6 is wound around the shaft core 14 by winding only the separator 13, and is then overlapped and wound in the order of the separator 13, the negative electrode sheet 12, the separator 13, and the positive electrode sheet 11. Alternatively, a plurality of separators 13 are wound. The outermost electrode is the negative electrode sheet 12, and all the positive electrode sheets 11 are sandwiched between the inner peripheral side and the outer peripheral side of the negative electrode sheet 12 via the separator 13. In addition, the outermost periphery of the power generation element group 6 is also wound with one or more layers of the separator 13 to prevent a short circuit, and the winding end of the separator 13 is coated with an adhesive in advance on the flag surface. It is stopped with a tape (not shown).

  The positive electrode sheet 11 has a strip-like positive electrode metal foil (positive electrode current collector) made of an aluminum foil or an aluminum alloy foil, and the negative electrode sheet 12 is a strip-like negative electrode metal foil (negative electrode current collector) made of a copper foil or a copper alloy foil. Body). The separator 13 is made of a microporous sheet material through which lithium ions can pass. In this example, a polyethylene sheet having a thickness of several tens of μm is used.

  A positive electrode active material mixture containing a lithium-containing transition metal double oxide such as lithium manganate is applied to both surfaces of the positive electrode metal foil of the positive electrode sheet 11 as a positive electrode active material. ) To form a positive electrode mixture layer (positive electrode mixture coating portion) 11b, and both sides of the positive electrode metal foil with the positive electrode active material mixture uncoated with the positive electrode active material mixture exposed on one side along the longitudinal direction. An exposed portion (positive electrode uncoated portion) 11a is formed.

  A negative electrode active material mixture containing a carbon material such as graphite capable of occluding and releasing lithium ions is applied to both surfaces of the negative electrode metal foil of the negative electrode sheet 12 as a negative electrode active material. The negative electrode mixture layer (negative electrode mixture coating part) 12b is formed, and the negative electrode metal foil exposed part (the negative electrode metal foil uncoated with the negative electrode active material mixture is exposed on one side along the longitudinal direction on both sides ( A negative electrode uncoated portion) 12a is formed.

  The positive electrode sheet 11 and the negative electrode sheet 12 are formed so that the winding axis direction length of the negative electrode mixture layer 12b is longer than the winding axis direction length of the positive electrode mixture layer 11b. In the positive electrode sheet 11, the winding axis direction both side end positions of the positive electrode mixture layer 11b are winding axes more than the boundary position between the winding axis direction central portion 14A and the winding axis direction end portion 14B of the shaft core 14 described later. It is wound around the shaft core 14 so as to be arranged at a position closer to the center in the direction. Further, the negative electrode sheet 12 has an axial core such that the positions of both ends of the negative electrode mixture layer 12b in the winding axis direction are located at positions outside the winding axis in the winding axis direction than the positions of both ends of the positive electrode mixture layer 11b in the winding direction. 14 is wound.

  The positive electrode sheet 11 and the negative electrode sheet 12 have a positive electrode metal foil exposed portion 11a disposed on one side of the winding axis direction, a negative electrode metal foil exposed portion 12a disposed on the other side of the winding axis direction, and the positive electrode mixture layer 11b and the negative electrode The separator 13 is overlapped with the mixture layer 12b so as to be wound around the shaft core 14. A positive electrode metal foil laminated portion 11c in which the positive electrode metal foil exposed portion 11a is wound and stacked is formed at one end of the power generation element group 6 in the winding axis direction. At the end, a negative electrode metal foil laminated portion 12c in which the negative electrode metal foil exposed portion 12a is wound and stacked is formed.

  5A and 5B are diagrams for explaining the configuration of the shaft core 14, FIG. 5A is an external perspective view of the shaft core 14, and FIG. 5B is an enlarged view of a portion B of FIG. 5A, which is a main part of the shaft core 14. It is a perspective view which shows a part in cross section. For easy understanding of the description, the winding axis direction of the shaft core 14 is perpendicular to the X direction, the direction perpendicular to the plane of the shaft core 14 is Z direction, and the X direction of the shaft core 14 is orthogonal to the Z direction. The direction will be described as the Y direction.

  The shaft core 14 is formed of an insulating material, and in particular, at least one resin material of PP (polypropylene) resin, PBT (polybutylene terephthalate) resin, PPS (polyphenylene sulfide) resin, and PEEK (polyether ether ketone) resin. It is formed using.

  The shaft core 14 is a rectangular plate-like member corresponding to the planar shape of the power generation element group 6, and is provided at the center position in the X direction, and the negative electrode mixture of the positive electrode mixture layer 11 b of the positive electrode sheet 11 and the negative electrode sheet 12. A central portion 14A corresponding to a portion where the layer 12b overlaps, and end portions 14B and 14B provided at positions on both sides in the X direction of the central portion 14A and corresponding to the positive electrode metal foil exposed portion 11a and the negative electrode metal foil exposed portion 12a, respectively. I have.

  The shaft core 14 has a shape in which the end portion 14B is narrower in the Y direction than the center portion 14A. For example, the shaft portion 14 is formed by forming tapered portions 14b at four corners of a rectangular plate member. The width is narrowed. The central portion 14A of the shaft core 14 has a pair of parallel outer edge portions 14a and 14a extending along the X direction. The end portion 14B of the shaft core 14 has a side end face 14e having a plate width V2 that is narrower than the plate width V1 of the outer edge portions 14a, 14a.

  The shaft core 14 has a positive electrode mixture layer 11b of the positive electrode sheet 11 and a negative electrode mixture layer 12b of the negative electrode sheet 12 arranged at the center portion 14A, and the positive electrode metal foil exposed portion 11a and the negative electrode metal foil exposed portion at the end portions 14B and 14B. 12a is disposed, and a separator 13 is interposed between the positive electrode mixture layer 11b and the negative electrode mixture layer 12b, and the positive electrode metal foil exposed portion 11a is disposed at the end portion 14B on one side in the X direction of the shaft core 14. The negative electrode metal foil exposed portion 12a is wound on the other end 14B.

  The end portion 14B of the shaft core 14 is formed so that the plate width in the Y direction becomes narrower as it moves in the direction away from the central portion 14A along the X direction. That is, the shaft core 14 is formed with tapered portions 14b at the four corners of the rectangular shaft core 14, and the plate width of the shaft core 14 is narrower than the plate width of the central portion 14A. Further, the shaft core 14 is formed with tapered portions 14b at the four corners, so that the lateral width (the length in the winding axis direction) along the X direction of the central portion 14A is the lateral width (the length in the winding axis direction) of the positive electrode mixture layer 11b. ) Is set larger. The lateral width of the central portion 14A and the lateral width of the negative electrode mixture layer 12b are set to match. With this configuration, ions are efficiently moved during charging / discharging between the positive electrode metal foil of the positive electrode sheet 11 and the negative electrode metal foil of the negative electrode sheet 12.

  Concave portions 14c and 14c are cut out at both end portions of the shaft core 14 in the X direction. Each recess 14c has a rectangular shape in which the extension 52 of the reinforcing member 51 is inserted. The size of the recess 14c in the X direction is substantially the same as the height h (see FIG. 8A) of the extension 52, and the size of the recess 14c in the Y direction (plate width direction) is the width of the extension 52. It is set slightly larger than w (see FIG. 8A). And the slit 15 (refer FIG. 5B) for engaging the reinforcement member 51 is provided in the side end surface 14d which faces the winding-axis direction outer side within the recessed part 14c.

  The reinforcing members 51 reinforce the strength of the power generation element group 6 in the winding axis direction, and are attached to both ends of the power generation element group 6 in the winding axis direction. A positive electrode metal foil laminate portion 11c and a negative electrode metal foil laminate portion 12c are provided at both ends in the winding axis direction of the power generation element group 6, and are easily deformed by an external force. Therefore, the reinforcing member 51 is provided in order to prevent deformation of the positive electrode metal foil laminate portion 11c and the negative electrode metal foil laminate portion 12c.

  The reinforcing member 51 is a high-strength member, and a member obtained by applying an insulating layer to an aluminum alloy, a copper alloy, or an aluminum alloy, polyphenylene sulfide (PPS), polypropylene (PP), or the like is used. As shown in FIG. 3, the pair of reinforcing members 51 are arranged continuously at both ends of the axial core 14 in the winding axis direction, and extend from the axial core 14 in the winding axis direction to end faces of the power generation element group 6. It protrudes further outward in the winding axis direction, and has a configuration that faces the side wall portion PN of the battery can 2 with a predetermined gap.

  6 is an enlarged perspective view showing a cross section taken along line AA of FIG. 1, FIG. 7 is a diagram showing an engagement portion between the reinforcing member 51 and the shaft core 14, and FIGS. FIG.

  As shown in FIGS. 6 and 7, the reinforcing member 51 has one end (abutting surface 52 a) facing and abutting on the side end surface 14 d of the shaft core 14, and the shaft core 14 is continuously extended in the winding axis direction. The other end of the extension element 52 protrudes outward in the winding axis direction from the power generation element group 6 and the current collecting connection pieces 24B and 34B, and the other end of the extension part 52 extends in a direction perpendicular to the extension part 52. It extends in a planar shape, and has a facing surface portion 53 that faces the side wall portion PN of the battery can 2 with a predetermined gap, and has a substantially T-shaped cross section.

  As shown in FIG. 8A, the extension portion 52 has a substantially rectangular plate shape with a predetermined plate thickness and a size that allows the outer shape to be accommodated in the recess 14c. It has a flat plate shape extending from the bottom wall portion PB to the vicinity of the opening portion (see FIG. 3) and facing the end portion on one side of the power generation element group 6 in the winding axis direction.

  An insertion piece 54 that constitutes an engagement means for engaging the reinforcing member 51 with the shaft core 14 is provided on the contact surface 52 a of the extension 52. The insertion piece 54 has a thin plate shape that can be inserted into the slit 15 of the shaft core 14.

  A plurality of reinforcing ribs 55 are provided between the extension portion 52 and the facing surface portion 53 of the reinforcing member 51 to improve the rigidity. As shown in FIG. 8B, the reinforcing member 51 may further improve the rigidity by forming the extension 52 in a trapezoidal cross section. When the configuration of the reinforcing rib 55 in FIG. 8A and the configuration of the trapezoidal cross section in FIG. 8B are compared, the reinforcing member 51 can be reduced in weight in FIG. 8A, while the rigidity in FIG. 8B is higher. Can be obtained. Further, as shown in FIG. 8C, the reinforcing rib 55 of FIG. 8A may be omitted to further reduce the weight.

  The reinforcing member 51 is formed by winding the power generating element group 6 after the positive electrode metal foil laminated portion 11c and the negative electrode metal foil laminated portion 12c of the power generating element group 6 are joined to the current collecting terminals 24 and 34 to form a power generating element assembly. Attached to both ends in the axial direction. Then, the entire power generation element group 6 including the reinforcing member 51 and the current collecting terminals 24 and 34 is housed in the battery can 2 in a state of being covered and covered with the insulating protective sheet 9. Therefore, in the reinforcing member 51, for example, as shown in FIG. 6, the insulating protective sheet 9 is interposed between the facing surface portion 53 of the reinforcing member 51 and the side wall portion PN of the battery can 2.

  Next, a method for manufacturing a lithium ion secondary battery having the above configuration will be described.

  In the method of manufacturing the lithium ion secondary battery 1, first, the positive electrode terminal 21 and the negative electrode terminal 31 are attached to the battery lid 3 to create a lid assembly, and the power generation element group 6 shown in FIG. 4 is created. Then, the lid assembly and the power generation element group 6 are integrated to create a power generation element assembly, and the reinforcing member 51 is attached to the power generation element group 6 of the power generation element assembly.

  Then, the entire power generation element group 6 including the reinforcing member 51 and the current collecting terminals 24 and 34 is covered and covered with the insulating protective sheet 9 and inserted into the battery can 2. Then, the battery lid 3 is laser welded to the battery can 2 to seal the opening of the battery can 2, and thereafter, an electrolytic solution (not shown) is injected into the battery can 2 from the liquid inlet 42. After injecting the electrolytic solution, the injection port 42 is sealed with an injection plug 43 and laser welding is performed.

  Prior to integrating the power generation element group 6 and the current collecting terminals 24 and 34, a pair of positive electrode connection portions 11d and 11d are formed at one end of the power generation element group 6 in the winding axis direction and the other end in the winding axis direction A pair of negative electrode connecting portions 12d and 12d is formed in the portion. As shown in FIG. 10A, the pair of positive electrode connection portions 11d and 11d and the pair of negative electrode connection portions 12d and 12d are respectively formed by connecting the positive electrode metal foil laminate portion 11c and the negative electrode metal foil laminate portion 12c of the power generation element group 6 to the axial core 14 respectively. Are compressed in two in the flat thickness direction (Z direction) and assembled together. As a result, the positive electrode metal foil laminate portion 11c and the negative electrode metal foil laminate portion 12c of the power generation element group 6 are each pushed open from the inner peripheral side to the outer side, and are expanded to have a substantially V-shaped cross section. The

  Then, the power generation element group 6 is approached from below the lid assembly, the positive electrode metal foil laminate portion 11c is inserted between the pair of positive electrode current collector connection pieces 24B, and between the pair of negative electrode current collector connection pieces 34B. The negative electrode metal foil laminated portion 12c is inserted into As a result, as shown in FIG. 10B, the inner surfaces of the pair of positive electrode current collector connection pieces 24B of the positive electrode current collector terminal 24 are opposed to the outer surfaces of the pair of positive electrode connection portions 11d and 11d, The inner surfaces of the pair of negative electrode current collector connection pieces 34B of the negative electrode current collector terminal 34 are arranged to face each outer surface of the connection portions 12d and 12d.

  Then, an ultrasonic bonding vibrator (horn) and stator (anvil) are thickened in the figure for the positive electrode connection part 11d and the positive electrode current collector connection piece 24B, in which the outer surface and the inner surface are opposed to each other. Approaching from the direction indicated by the arrow, the positive electrode connection portion 11d and the positive electrode current collector connection piece 24B are sandwiched between the vibrator and the stator, and ultrasonic bonding is performed. Similarly, the negative electrode connection portion 12d and the negative electrode current collecting connection piece 34B, whose outer surfaces and inner surfaces are arranged to face each other, are sandwiched between an ultrasonic bonding vibrator (horn) and a stator (anvil), respectively, and ultrasonic waves Join. As a result, the power generation element group 6 is supported in a state of being electrically connected to the positive electrode current collector terminal 24 and the negative electrode current collector terminal 34, thereby forming a power generation element assembly.

  Then, as shown in FIG. 10C, a step of attaching a pair of reinforcing members 51, 51 to both ends of the power generation element group 6 in the winding axis direction is performed. As shown in FIG. 9, the reinforcing member 51 is approached from the outside in the winding axis direction with respect to the power generation element group 6, and a pair of positive electrode connecting portions 11 d in which the extension portion 52 is expanded in a substantially V-shaped cross section. 11d and between the pair of negative electrode connecting portions 12d and 12d. Then, as shown in FIG. 7, the insertion piece 54 provided in the extension portion 52 is inserted into the slit 15 of the shaft core 14, and the contact surface 52 a of the extension portion 52 contacts the side end surface 14 d of the shaft core 14. It is engaged with the shaft core 14 in contact.

  The lithium ion secondary battery 1 according to the present embodiment described above can exhibit the following operational effects.

(1) The shaft core 14 is attached to one end and the other end in the winding axis direction, extends the shaft core outward in the winding axis direction, protrudes from the end face of the power generation element group 6, and the side wall of the battery can Since the reinforcing member 51 is opposed to the part PN, an external force acts on the lithium ion secondary battery 1 due to vibration, impact, automobile collision, or the like, and the power generation element group 6 is wound relative to the battery can 2. When moved in a direction along the axial direction, the reinforcing member 51 can be brought into contact with the side wall portion PN of the battery can 2.

  Since the power generation element group 6 is supported between the positive electrode current collection connection piece 24B and the negative electrode current collection connection piece 34B that protrude in a pair from the battery lid 3, the power generation element group 6 has a power generation element with respect to the lithium ion secondary battery 1. When an external force in a direction along the winding axis direction of the group 6 is applied, there is a risk of moving in the battery can 2 along the direction.

  Under such conditions, in the lithium ion secondary battery 1 according to the present embodiment, the reinforcing member 51 protrudes outward in the winding axis direction from the power generation element group 6 and faces the side wall portion PN of the battery can 2. When the power generation element group 6 moves relatively in the above-described direction, the reinforcing member 51 can be brought into contact with the side wall portion PN of the battery can 2. The energy applied to the reinforcing member 51 by the contact is transmitted from the reinforcing member 51 to the shaft core 14 and absorbed. Therefore, it is possible to prevent the end of the power generation element group 6 on the outer side in the winding axis direction from coming into contact with the side wall PN of the battery can 2 to be deformed or crushed, and to suppress occurrence of a short circuit or the like.

(2) When the external force in the direction along the winding axis direction of the power generation element group 6 acts on the lithium ion secondary battery 1 and the battery can 2 is deformed in the direction of contracting in the long side direction. The one reinforcing member 51 can be brought into contact with the one side wall PN of the battery can 2, and the other reinforcing member 51 can be brought into contact with the other side wall PN of the battery can 2. Therefore, the pair of reinforcing members 51 supported by the shaft core 14 and both ends of the winding axis direction are interposed between the pair of side wall portions PN and PN, and the space between the pair of side wall portions PN and PN is interposed. It is possible to support and prevent the pair of side wall parts PN and PN from moving further toward each other. Therefore, it is possible to prevent the end of the power generation element group 6 on the outer side in the winding axis direction from coming into contact with the side wall PN of the battery can 2 to be deformed or crushed, and to suppress occurrence of a short circuit or the like.

(3) The facing surface portion 53 of the reinforcing member 51 extends in a planar shape in a direction orthogonal to the extension portion 52 continuously from the base end of the extension portion 52, and a predetermined gap is formed between the side wall portion PN of the battery can 2. And are arranged opposite to each other. The power generation element group 6 extends with a constant width from the bottom wall portion PB of the battery can 2 to the vicinity of the opening along the outer end in the winding axis direction.

  Therefore, the reinforcing member 51 can be opposed to the side wall portion PN of the battery can 2 with an area larger than the cross-sectional area in the direction orthogonal to the winding axis direction of the shaft core 14. Therefore, for example, when an external force acts in a direction in which the battery can 2 is crushed in the longitudinal direction and a part of one side wall PN of the battery can 2 is deformed toward the inside of the battery can 2, The side wall portion PN can be held by reliably abutting 53. Therefore, it is possible to prevent the end of the power generation element group 6 on the outer side in the winding axis direction from coming into contact with the side wall PN of the battery can 2 to be deformed or crushed, and to suppress occurrence of a short circuit or the like.

(4) The lithium ion secondary battery 1 according to the present embodiment is formed with a pair of connection portions 11d and 12d at the outer end in the winding axis direction of the power generation element group 6, and the pair of connection portions 11d and 12d. The power collecting element group 6 is supported by the lid assembly by ultrasonically bonding the current collecting connection pieces 24B and 34B of the current collecting terminal to each other. Therefore, in the ultrasonic bonding process, a space for inserting the ultrasonic bonding transducer and the stator at the outer end of the power generation element group 6 in the winding axis direction is necessary. Therefore, for example, the reinforcing member 51 cannot be provided before the power generating element group 6 is attached to the lid assembly, for example, the shaft core 14 and the reinforcing member 51 are integrally formed. The reinforcing member 51 is attached to the power generation element group 6 after ultrasonically joining the connection portions 11d and 12d of the power generation element group 6 to the current collector connection pieces 24B and 34B of the current collecting terminals, and when an external force is applied. In addition, it is possible to prevent the end of the power generation element group 6 on the outer side in the winding axis direction from being deformed or crushed by contacting the side wall PN of the battery can 2.

  In the above-described embodiment, the structure in which the reinforcing member 51 is engaged with the shaft core 14 by inserting the insertion piece 54 of the reinforcing member 51 into the slit 15 formed on the end surface of the shaft core 14 has been described. The structure to be performed is not limited to the above-described configuration, and may be another configuration. Other configurations will be described below with reference to FIGS. Note that the same components as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  11-13 is a figure explaining the other structure which engages the reinforcement member 51 with the axial core 14, FIG. 11 is a perspective view of a reinforcement member, FIG. 12 used the reinforcement member of FIG. FIG. 13 is a longitudinal sectional view of the lithium ion secondary battery, and FIG. 13 is a sectional view taken along the line CC of FIG.

  In this embodiment, the slit 56 is provided in the reinforcing member 51 as the engaging means, and the insertion piece 16 is provided in the shaft core 14. The slit 56 is formed to open in the contact surface 52a of the extension portion 52 of the reinforcing member 51, and has a concave groove shape extending along the lateral width direction of the extension portion 52 at a predetermined depth. The insertion piece 16 has a thin plate shape having a predetermined width and protruding from the side end surface 14 d of the shaft core 14 by a predetermined length, and the size thereof is set to a dimension that can be fitted into the slit 56. .

  The reinforcing member 51 having the above-described configuration is attached to the power generation element group 6 by causing the reinforcement member 51 to approach from the outside in the winding axis direction of the power generation element group 6 and the extension portion 52 is expanded in a substantially V-shaped cross section. It inserts between a pair of positive electrode connection parts 11d and 11d and between a pair of negative electrode connection parts 12d and 12d. Then, the insertion piece 16 of the shaft core 14 is inserted into the slit 56 provided at the tip of the extension portion 52, and the shaft core 14 is in a state where the contact surface 52 a of the extension portion 52 is in contact with the end surface of the shaft core 14. Engage with.

  According to the above configuration, the reinforcing member 51 can be engaged with the shaft core 14 by inserting the insertion piece 16 of the shaft core 14 into the slit 56 of the reinforcing member 51, and the reinforcing member 51 can be easily attached to the power generation element 6. Can be attached to. Further, since the insertion piece 16 is inserted and engaged with the slit 56, when an external force is applied to the reinforcing member 51 from the outside in the winding axis direction along the winding axis direction, the contact of the reinforcing member 51 is prevented. The contact surface 52a and the side end surface 14d of the shaft core 14 can be held in contact with each other, and the impact energy input to the reinforcing member 51 can be reliably transmitted to the shaft core 14 and dispersed. .

  14 and 15 are diagrams for explaining still another embodiment of the holding structure of the reinforcing member 51, FIG. 14 is a perspective view of the reinforcing member, and FIG. 15 is a lithium ion using the reinforcing member of FIG. It is a longitudinal cross-sectional view of a secondary battery.

  In this embodiment, the engaging claw 57 is provided in the reinforcing member 51 as the engaging means, and the engaging hole 17 in which the engaging claw 57 is engaged is provided in the shaft core 14. The locking claws 57 protrude from the contact surface 52 a of the extension 52 of the reinforcing member 51, and are provided in pairs with a predetermined distance apart in the length direction of the reinforcing member 51. The locking hole 17 is recessed in the side end surface 14 d of the shaft core 14 and has a hole shape for locking the inserted locking claw 57.

  According to the above configuration, the reinforcing member 51 is approached from the outside in the winding axis direction of the power generation element group 6, and the locking claw 57 of the reinforcing member 51 is inserted and locked in the locking hole 17 of the shaft core 14. Can do. Therefore, the reinforcing member 51 can be reliably engaged with the shaft core 14, and for example, the reinforcing member 51 can be prevented from coming off during the assembly operation.

  16 to 18 are views for explaining still another embodiment of the mounting structure of the reinforcing member 51, FIG. 16 is a perspective view of the reinforcing member, and FIG. 17 is a lithium ion using the reinforcing member of FIG. FIG. 18 is a perspective view for explaining a mounting method of the reinforcing member.

  In the present embodiment, the protrusion 18 is provided on the side end surface 14 e of the shaft core 14 as the engaging means, and the fitting hole 58 is provided in the facing surface portion 53 of the reinforcing member 51. The protrusions 18 are provided as a pair on the side end face 14e of the shaft core 14 and at a position separated outward in the Y direction from the recess 14c. The protrusion 18 has a cylindrical shape that protrudes outward from the end face of the power generation element group 6 in the winding axis direction.

  The fitting hole 58 is provided so as to penetrate through the facing surface portion 53 of the reinforcing member 51, and is open at a position on the outer side in the lateral width direction from the extension portion 52 and facing the protruding portion 18. The fitting hole 58 has a round hole shape into which the protruding portion 14 can be fitted.

  According to the above configuration, the reinforcing member 51 is brought into engagement from the outer side in the winding axis direction of the power generation element group 6 and the projecting portion 18 of the shaft core 14 is fitted into the fitting hole 58 of the reinforcing member 51. be able to. Therefore, the reinforcing member 51 can be reliably engaged with the shaft core 14, and for example, the reinforcing member 51 can be prevented from coming off during the assembly operation. In particular, according to the present embodiment, the engaged state can be visually recognized, and the workability can be improved.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Square battery 2 Battery can 6 Power generation element group 11 Positive electrode sheet 11c Positive electrode metal foil lamination | stacking part 11d Positive electrode connection part 12 Negative electrode sheet 12c Negative electrode metal foil lamination | stacking part 12d Negative electrode connection part 13 Separator 14 Axle core 14d, 14e Side end surface 15 Slit Combined means)
51 Reinforcing member 52 Extension part 53 Opposing surface part 54 Insertion piece (engagement means)
PN side wall

Claims (10)

In a prismatic battery having a flat power generation element group in which a positive electrode sheet and a negative electrode sheet are stacked with a separator interposed therebetween and wound around an axis, and a battery can accommodating the power generation element group,
A prismatic battery comprising: a pair of reinforcing members extending from the power generation element group to the outside in the winding axis direction by extending the shaft core to both sides in the winding axis direction of the shaft core. The reinforcing member is
One end abuts on the side end surface of the shaft core, and the other end protrudes outward in the winding axis direction from the power generation element group, and
The rectangular battery according to claim 1, further comprising: an opposing surface portion that extends in a planar shape in a direction orthogonal to the extension portion continuously to the other end of the extension portion and faces the side wall portion of the battery can. The power generation element group includes a pair of positive electrode connection portions obtained by dividing the positive electrode metal foil laminated portion of the positive electrode sheet formed at one end portion in the winding axis direction into two in the flat thickness direction from the shaft core, respectively. A pair of negative electrode connecting portions each of which is formed by dividing the negative electrode metal foil laminated portion of the negative electrode sheet formed on the other side of the winding axis direction into two in the flat thickness direction from the axial core,
The reinforcing member is characterized in that the extension portion is inserted between the pair of positive electrode connection portions, and the facing surface portion is disposed opposite to the winding shaft direction outer side than the pair of positive electrode connection portions. Item 3. The prismatic battery according to Item 2.   The prismatic battery according to any one of claims 1 to 3, further comprising engagement means for engaging the reinforcing member with the shaft core.   The said engaging means has the slit formed in the side end surface of the said shaft core, and the insertion piece which protrudes from the said extension part of the said reinforcement member, and can be inserted in the said slit. Square battery.   The engaging means includes an insertion piece formed to protrude from a side end surface of the shaft core, and a slit that is recessed in the extension portion of the reinforcing member and into which the insertion piece can be inserted. The prismatic battery according to claim 4.   The engaging means includes a locking hole recessed in a side end surface of the shaft core, and a locking claw that protrudes from the extension portion of the reinforcing member and can be locked in the locking hole. The prismatic battery according to claim 4.   The engaging means includes a protruding portion protruding from a side end surface of the shaft core, and a fitting hole recessed in the facing surface portion of the reinforcing member and capable of fitting the protruding portion. The prismatic battery according to claim 4.   The prismatic battery according to claim 2, wherein the reinforcing member is provided with a reinforcing rib between the extension portion and the facing surface portion.   The prismatic battery according to claim 2, wherein the reinforcing member has a substantially trapezoidal cross section that gradually expands as the extension portion moves in a direction approaching the facing surface portion.

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