JP2010027436A - Sealed battery and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed battery which improves the sealing property of a connecting part of a battery case and a lid by welding, and is able to maintain high hermetic state. <P>SOLUTION: The battery 10 is equipped with a case body 20, formed with an opening 21 on a case top face, and the lid 30 having a protruding part 34 entering interiors of an outer rim part 32, contacting an opening end face 24 and the opening 21, when mounted on the opening end face 24 equivalent to a top face 23 of a side wall 22 of the case body 20. An inclined face part 26 is formed between a vertical inner wall surface 25 and the horizontal opening end face 24 from the inner wall surface 25 to the opening end face 24 in the sidewall 22, and the lid 30 is formed with an inclined protruding side face 35 corresponding to the inclined face part 26, in at least on part of a protruding part 34 side face. The case body 20 and the lid 30 are jointed, by melting an area to a boundary portion of the inclined face part 26 and the inclined protruding part side face 35 over the opening end face 24 by welding from a case side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sealed battery, and more particularly to a sealed battery having a structure in which a case body and a lid are joined by welding and a method for manufacturing the sealed battery.

  In recent years, lithium-ion batteries, nickel-metal hydride batteries, and other secondary batteries have become increasingly important as on-vehicle power supplies or personal computers and portable terminals. In particular, a lithium ion battery that is lightweight and obtains a high energy density is expected to be preferably used as a high-output power source mounted on a vehicle.

In one aspect of the lithium ion battery, an electrode body, an electrolytic solution, and the like are accommodated in a metal (typically aluminum) battery case, and a metal (typically aluminum) is formed in the opening of the battery case. The lid is made by attaching a contact portion between the battery case and the lid by welding such as laser welding. Examples of this type of prior art include Patent Documents 1 and 2.
In the battery disclosed in Patent Document 1, the back surface of the lid (the surface arranged on the inner side of the case when the lid is attached to the battery case) is located inside the battery case when the lid is attached. The convex part which penetrates is provided. Therefore, when such a lid is attached to the battery case, the lid is in contact with the upper surface (in the side wall) of the case and part of the inner wall surface (near the periphery of the opening). And the contact part of such a cover and a case is laser-welded from the side of this case.

JP-A-11-77347 Japanese Patent Laid-Open No. 10-144268

  According to the technology described in Patent Document 1, in a lithium ion battery including a welded portion including the contact portion, a portion of the welded portion that is close to the outer wall surface of the case side wall (that is, a portion that is close to a portion directly irradiated with laser). , A melting portion (a portion where the base material (that is, the lid and the case) is melted in the welded portion). For this reason, thermal contraction accompanying welding occurs and compressive stress is generated. On the other hand, in order to avoid the entry of foreign matter such as spatter into the case during welding, it is preferable that the welded molten part does not reach the inner wall surface of the case side wall (does not penetrate). In such a case, a tensile stress can be generated on the outer wall surface side in the non-melted portion on the inner wall surface side. For this reason, in the welded portion between the battery case and the lid, cracks occur because compressive stress in the melted portion and tensile stress in the non-melted portion can act on both the outer wall surface side and the inner wall surface side of the side wall. As a result, the airtightness of the battery may be reduced.

  Moreover, according to the technique of patent document 2, the inner periphery of the opening part of a battery case main body is formed in the taper shape of the hole side of an outward opening so that a lid | cover may be received. On the other hand, in the lid, the outer periphery of the lid is formed as an axial taper that fits into the taper of the opening. Then, after the lid is fitted into the opening of the case body, laser welding is performed from above with the contact portion between the tapers facing the upper surface of the lid. Here, since the weld including the contact portion is substantially on the taper surface, the taper surface direction and the laser irradiation direction are different. As a result, the balance of thermal stress that can occur in the welded portion is deteriorated, and a good and stable joining state between the battery case and the lid cannot be maintained.

  The present invention has been made in view of such points, and its main purpose is to provide a sealed battery capable of maintaining high airtightness by improving the sealing performance of the joint portion between the battery case and the lid by welding. Is to provide. Another object is to provide a method for suitably manufacturing such a sealed battery.

  In order to achieve the above object, a sealed battery provided by the present invention is a case main body that accommodates an electrode body, and an opening for accommodating the electrode body is formed on the upper surface of the case; A lid that is placed on an opening end surface corresponding to the upper surface of the side wall of the case main body that forms the periphery of the opening, and an outer edge that contacts the opening end surface when the lid is placed; A lid having a convex portion formed on the back surface side and entering the inside of the opening when placed. In this sealed battery, the case body and the lid body have a predetermined region including a boundary line between the case body side wall and the outer edge portion of the lid body in a state where the lid body is placed on the opening end surface. They are joined to each other by being melted by welding from the side of the case. Here, on the side wall of the case body constituting the periphery of the opening, an inner wall surface that forms the inner surface of the case body and extends in the vertical direction, and the opening end surface that forms the upper surface of the case body and extends in the horizontal direction An inclined surface portion is formed between the horizontal opening end surface and the vertical inner wall surface. In the lid, an inclined convex portion side surface corresponding to the inclined surface portion is formed on at least a part of the side surface of the convex portion. And the area | region fuse | melted by the said welding has extended to the boundary site | part of the said inclined surface part and the said inclined convex part side surface beyond the said opening end surface.

In this specification, the “battery” refers to a power storage device that can extract predetermined electrical energy, and is not limited to a specific power storage mechanism (configuration of electrode body or electrolyte). A lithium secondary battery such as a lithium ion battery, a secondary battery such as a nickel hydride secondary battery, or a physical battery such as an electric double layer capacitor is a typical example included in this battery.
In this specification, the “electrode body” refers to a structure that includes at least one positive electrode and one negative electrode and forms the main body of a battery (power storage device).

  According to the sealed battery having the above configuration, the contact portion between the case main body and the lid body has a boundary portion (contact surface) between the inclined surface portion of the case main body and the inclined convex side surface on the back surface side of the lid body. Is included. When welding such a contact portion from the side of the case body, if the region melted by the welding (that is, the melted portion) extends beyond the opening end surface to the boundary portion, the heat shrinkage due to the welding is performed. The compressive stress that can be generated along with the above can act in a direction toward the boundary portion on both sides (that is, the lid body side and the case body side) sandwiching the boundary portion. As a result, of the compressive stress that can occur in the melted portion between the case body and the lid body, the inner wall surface side of the case body (that is, the portion having the inclined surface portion and the inclined convex portion side surface as a boundary and its vicinity) The compressive stress may be generated in a direction inclined at an inclination angle corresponding to the inclined surface portion and the inclined convex portion side surface. The compressive stress on the inner wall surface side that can be generated in such an inclination direction can be balanced with the compressive stress on the outer wall surface side (that is, the region having the opening end surface as a boundary and its vicinity). Therefore, according to the present invention, the above-mentioned case main body that can suppress the occurrence of cracks and the like in the welded portion (melted portion) due to the imbalance of stress, and can maintain the joined state stably with high welding (joining) strength. A highly airtight sealed battery including the lid can be obtained.

  In addition, in the battery having a configuration that does not have the inclined surface portion of the case body side wall and the inclined convex portion side surface of the lid body, the contact portions are arranged on the case side for the purpose of firmly joining the case body and the lid body. When welding from one side, it may be completely melted to the inner wall surface side of the side wall. However, as described above, in such a case, there is a possibility that foreign matters such as spatter may enter the case. Here, according to the sealed battery according to the present invention, by providing the inclined surface portion and the inclined convex portion side surface corresponding to the inclined surface portion, the case main body with high joint strength can be obtained without melting to the inner wall surface side during welding. And the contact part of a cover body can be joined. In addition, the said inclined surface part should just incline toward the vertical inner wall face from the said horizontal opening end surface, The surface may be a plane or a curved surface. Further, the side surface of the inclined convex portion only needs to correspond to the surface shape of the inclined surface portion, and may be a flat surface or a curved surface.

  In a preferred aspect of the sealed battery disclosed herein, a concave portion is formed on the front surface side of the lid body at a portion substantially corresponding to the convex portion on the back surface side, and from the periphery of the concave portion to the inside of the concave portion. A side surface of the inclined recess reaching the bottom surface is formed. Here, the side surface of the inclined convex portion and the side surface of the inclined concave portion are formed so as to be substantially parallel when viewed from the cross section of the lid. When welding the case main body and the lid body, pressing (pressing) the side surface of the inclined concave portion between the inclined surface portion and the side surface of the inclined convex portion of the contact portion between the case main body and the lid body. Since the contact part (boundary part) can be pressed from the surface side of the lid so as to be substantially perpendicular to the boundary part, as a result, the case body and the lid can be more firmly joined.

In another preferable aspect of the sealed battery disclosed herein, the inclined surface portion is inclined at an inclination angle of 30 to 60 ° from the vertical direction. In a further preferred aspect, the width in the wall thickness direction of the case body side wall at the opening end surface is defined to be 40 to 60% of the wall thickness of the case body side wall.
Since the inclined surface portion and the opening end surface have such dimensions, they can be easily formed on the upper surface of the case body side wall. Further, when the case body and the lid are welded, the magnitude and direction of the compressive stress that can be generated at the boundary portion between the inclined surface portion and the inclined convex portion side surface in the melted portion is defined by using the opening end surface as a boundary. Therefore, the case main body and the lid can be joined with higher joint strength.

Further, as the sealed battery disclosed herein, the wall thickness of the side wall of the case body and the plate thickness of the lid body are both preferably in the range of 0.3 mm to 1 mm, and the inclined surface portion is in the vertical direction. In this case, the battery is inclined at an inclination angle of 30 to 50 °.
Further, in the sealed battery disclosed herein, the inclined surface portion particularly preferably has a curved shape, and the wall thickness of the side wall of the case body and the plate thickness of the lid body are both in the range of 0.3 mm to 1 mm. And the inclined surface portion is an arc surface (typically a 1/4 arc surface) curved so as to swell toward the inner surface side of the case body, and the inclined convex portion side surface of the lid body corresponds to the arc surface. The battery is characterized by being curved in a circular arc shape (typically a 1/4 arc surface shape) of curvature.

In order to achieve the above object, the present invention provides a method of manufacturing a sealed battery having the above-described configuration. The method provided by the present invention includes the following (1) to (5). That is, (1) an opening formed on the upper surface of the case, an inner wall that forms an inner surface on the side wall that forms the periphery of the opening, and extends in the vertical direction, and an upper surface that forms the upper surface of the side wall and spreads in the horizontal direction A case main body having an opening end surface, wherein a case main body having an inclined surface portion extending from the horizontal opening end surface to the vertical inner wall surface is formed between the inner wall surface and the opening end surface; 2) An outer edge portion that comes into contact with the opening end surface when placed on the opening end surface, and a convex portion that is formed on the back surface side and enters the inside of the opening when placed. And (3) prepared from the opening, wherein a cover body is provided with an inclined convex portion side surface corresponding to the inclined surface portion formed on at least a part of the side surface of the convex portion. Accommodating the electrode body in the case body, (4) the opening Placing the lid on the surface, and (5) melting a predetermined region including a boundary line between the side wall of the case body and the outer edge of the lid by welding from the side of the case. Joining together. Here, at the time of the welding, at least the outer edge portion of the surface side of the lid, and the inclined concave side surface extending from the peripheral edge of the concave portion formed in a portion substantially corresponding to the convex portion to the bottom surface in the concave portion, , Welding is performed so that the region to be melted by welding extends beyond the opening end surface to reach the boundary portion between the inclined surface portion and the inclined convex portion side surface.
According to this manufacturing method, when the contact portion between the case body and the lid is joined by welding (typically laser welding) from the side of the case body, the region melted by the welding exceeds the opening end face. By welding so as to reach the boundary portion between the inclined surface portion and the inclined convex portion side surface, the contact portion can be firmly joined. In addition, the contact part can be joined more firmly by pressing the boundary part almost vertically from the surface side of the lid. On the other hand, since it is not necessary to ensure the joining strength by melting until it penetrates the inner wall surface of the case body by the welding, it is possible to effectively prevent the generation of foreign matters such as spatter that can enter the case. .

  In a preferred aspect of the manufacturing method disclosed herein, a pressing jig having a configuration having a surface shape of a region to be pressed is used for the pressing. Thereby, the horizontal contact site | part of the said opening end surface and an outer edge part and the contact site which inclined the said inclined surface part and the inclination convex part side surface can be pressed simultaneously and with equal force.

  The present invention also provides a vehicle equipped with any of the sealed batteries disclosed herein or a sealed battery manufactured by the method disclosed herein. In the sealed battery provided by the present invention, the case main body and the lid body can be firmly joined at the contact portion. Therefore, when such a sealed battery is mounted on a vehicle such as an automobile, vibration occurs during traveling. However, high airtightness at the joint between the case body and the lid body is maintained, and problems such as leakage of electrolyte inside the case can be prevented.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that matters other than the matters specifically mentioned in the present specification and necessary for the implementation of the present invention (for example, the configuration of the electrode body and the electrolyte, the preparation procedure of the electrode body, the construction procedure of the battery, etc. General technology related to construction, etc.) can be grasped as a design matter of a person skilled in the art based on conventional technology in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  Although not intended to be particularly limited, the present invention will be described in detail below by taking a sealed lithium ion battery 10 (hereinafter sometimes simply referred to as “battery”) as an example. Moreover, in the following drawings, the same code | symbol is attached | subjected to the member and site | part which show | plays the same effect | action, and the overlapping description may be abbreviate | omitted or simplified. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships.

The lithium ion battery 10 of the present embodiment will be described with reference to FIGS. FIG. 1 is a schematic perspective view showing an appearance of a battery 10 according to the present embodiment. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is a cross-sectional view schematically showing a contact portion between the lid body 30 and the case body 20 when the lid body 30 is placed on the opening end surface 24 of the case body 20. FIG. 4A is a cross-sectional view schematically showing a melting portion 80 when welded from the side of the case body 20 to the contact portion between the lid body 30 and the case body 20 of the battery 10 according to the present embodiment. Yes, (b) schematically shows the melting portion 80 when the case body 120 is welded from the side of the case body 120 to the contact portion between the lid body 130 and the case body 120 in the battery having a configuration in which the side wall of the case body does not have the inclined surface portion. FIG. FIG. 5 is a schematic cross-sectional view showing a part of the process of welding the contact portion between the lid 30 and the case main body 20 of the battery 10 according to the present embodiment. In the above figure, the cross section of the positive terminal 52 insulating member 56 and the nut 58 is not shown.
As shown in FIGS. 1 to 3, the overall configuration of the battery 10 according to this embodiment is typically the same as that of a conventional battery. An electrode body 60 (in this embodiment, a flat wound electrode body) including an active material, positive and negative current collectors, a separator, and the like, and the electrode body 60 and an appropriate electrolyte (typically liquid) A case main body 20 that houses an electrolyte) and a lid 30.

  With reference to FIG. 1 and FIG. 2, the structure of the case main body 20 which concerns on this embodiment is demonstrated. The case body 20 has a bottomed shape (in this embodiment, a box shape or a square shape) provided with an opening 21 for accommodating the electrode body 60 in the upper surface portion of the case. In the side wall 22 of the case body 20 that forms the periphery of the opening 21, an opening end surface 24 that extends in the horizontal direction P is formed on the upper surface 23 of the side wall 22. Further, the outer peripheral edge of the opening end face 24 is in contact with the outer wall surface 27 extending in the vertical direction Q on the side wall 22 in a vertical direction. On the other hand, the inner peripheral edge of the opening end surface 24 is inclined between the opening end surface 24 and the inner wall surface 25 extending in the vertical direction Q of the side wall 22 from the opening end surface 24 toward the inner wall surface 25. A surface portion 26 is formed.

  The inclined surface portion 26 is inclined at a predetermined inclination angle θ from the inner wall surface 25 spreading in the vertical direction Q. The inclination angle θ is preferably an inclination angle defined within a range of 30 to 60 °, more preferably within a range of 30 to 50 °, and particularly preferable examples include 30 ° or 45 °. It is done. When the inclination angle θ exceeds the upper limit of the above range, the inclination of the inclined surface portion 26 becomes too shallow. As will be described later, an inclined surface portion 26 is formed on the side surface portion of the convex portion 34 formed on the back surface side of the lid body 30 in order to fit the lid body 30 to the case body 20. For this reason, when the inclination of the inclined surface portion 26 becomes shallow, the degree of protrusion of the convex portion 34 also becomes small, so that the lid body 30 becomes difficult to fit into the case body 20, and the lid body 30 comes off from the case body 20. It becomes easy. On the other hand, when the inclination angle θ is below the lower limit of the range, the width of the opening end surface 24 (that is, the length of the side wall 22 in the wall thickness direction) is defined to be wide enough to allow the lid 30 to be easily placed. Then, the region (melted portion) melted at the time of welding the case main body 20 and the lid 30 is a boundary portion (the inclined surface portion 26 and the inclined convex portion side surface 35 between the inclined surface portion 26 and the inclined convex portion side surface 35 described later). The surfaces that are in contact with each other), and the effect of improving the bonding strength by the inclined surface portion 26 is not sufficiently exhibited.

  In the opening end surface 24, the width in the wall thickness direction of the side wall 22 of the case body 20 is preferably defined to be 40 to 60% with the wall thickness of the side wall 22 being 100%. If this width exceeds the upper limit of the above range, the inclination angle θ of the inclined surface portion 26 may depart from the preferred range and become too small. On the other hand, when the width of the opening end face 24 is below the lower limit of the range, the inclination angle θ of the inclined surface portion 26 deviates from the preferred range and becomes too large (that is, the inclination of the inclined surface portion 26 becomes too shallow). Further, it is difficult to place the lid 30 on the opening end surface 24 in a stable state. Accordingly, it is preferable that the width in the wall thickness direction of the side wall 22 of the opening end surface 24 is set in consideration of the inclination angle θ of the inclined surface portion 26 within the above range. For example, such a width can be defined between 0.2 mm and 0.3 mm if the wall thickness of the side wall 22 is 0.5 mm.

  The material of the case body 20 is preferably a metal material that is lightweight and has good thermal conductivity. For example, aluminum (including an aluminum alloy), stainless steel, nickel-plated steel, or the like can be preferably used. Further, the case body 20 is typically a plate material obtained by processing a material made of any of the above-described metal species (typically aluminum or an alloy thereof) using a conventionally known method. Is adopted. For example, the above metal material is melted and cast to obtain an ingot, the ingot is subjected to homogeneous heat treatment, hot rolling and cold rolling are performed to form a rolled plate, and the rolled plate is annealed. The method of obtaining a desired board | plate material by implementing cold rolling again until it becomes a desired board thickness is mentioned. The plate thickness at this time is preferably about 0.5 mm to 2.0 mm.

  A method of molding the case body 20 from the plate material thus obtained may be the same as the conventional method and is not particularly limited. For example, the plate material is cut into a predetermined shape, and this is subjected to drawing and ironing a plurality of times, so that it gradually becomes the outer shape of the case body 20 (in this embodiment, a flat box shape with a bottom). The case body 20 is obtained by forming the side wall 22 and finally trimming and finishing the upper surface 23 (that is, the opening end surface 24 and the inclined surface portion 26) of the side wall 22 into the shape as described above. It is done. The plate thickness (of the side wall 22) of the case body 20 thus obtained is preferably 0.3 mm to 1 mm, more preferably about 0.3 mm to 0.7 mm, and particularly preferably about 0.3 mm. 5 mm.

  Next, the configuration of the lid body 30 according to the present embodiment will be described together with the relationship with the case body 20 with reference to FIGS. The lid 30 has a shape that can close the opening 21 on the upper surface of the case body 20 (in this embodiment, a flat, substantially rectangular shape). The lid 30 is placed on the opening end surface 24 of the case body 20 and closes the opening 21. The lid body 30 includes an outer edge portion 32 that comes into contact with the opening end face 24 when placed on the opening end face 24, and a rear surface of the lid body 30 (when the lid body 30 is placed on the opening end face 24. And a convex portion 34 projecting to the side facing the inside of the case. An inclined convex portion side surface 35 corresponding to the inclined surface portion 26 is formed on at least a part of the side surface of the convex portion 34 (in the present embodiment, the entire side surface). For this reason, when the lid 30 is placed on the case body 20 (opening end surface 24), the back side surface 32a of the outer edge portion 32 is in contact with the opening end surface 24, and the convex portion 34 is the side surface of the inclined convex portion. In 35, it comes into the inside of the said opening part 21 in the state which contact | connected the said inclined surface part 26 (it fits). That is, the lid body 30 is fitted to the case body 20. Thus, the opening 21 of the case body 20 can be closed without a gap by the lid body 30. Further, when the lid body 30 is placed as described above, the outer wall surface 27 of the side wall 22 of the case body 20 and the outer peripheral end surface of the outer edge portion 32 of the lid body 30 are flush with each other (that is, identical to each other). (In the state of being on the surface).

On the front surface side of the lid body 30, a concave portion 36 is formed at a site substantially inside the outer edge portion 32 and corresponding to the convex portion 34 on the back surface side. Similarly to the inclined convex portion side surface 35 formed on the side surface of the convex portion 34, the concave portion 36 has an inclined concave side surface 37 that is inclined from the peripheral edge of the concave portion 36 toward the bottom surface 38 in the concave portion 36. Is formed. The inclined concave side surface 37 and the inclined convex side surface 35 are substantially parallel in a cross-sectional view of the lid body 30.
As described above, in the present embodiment, the side surface of the convex portion 34 of the lid body 30 is an inclined convex portion side surface 35 over the entire surface, and the inclined convex portion side surface 35 is an inclined surface portion on the side wall 22 of the case body 20. 26. As another embodiment, for example, a side surface corresponding to (in contact with) the inner wall surface 25 of the side wall 22 and extending in the vertical direction is formed on the side surface of the convex portion 34 in addition to the inclined convex portion side surface 35. When the lid 30 is placed on the opening end surface 24, the side surface of the convex portion 34 can contact the inclined surface portion 26 and the inner wall surface 25 (a part of the inner wall surface 25) continuing from the inclined surface portion 26. Such a form may be sufficient.

  As shown in FIG. 1 and FIG. 2, the lid 30 typically has two terminal extraction holes (not shown). The external connection terminals 52 and 54 are attached to the lid 30 through an insulating member 56 such as a collar in a state where the terminals 52 and 54 are inserted through the terminal extraction holes. The terminals 52 and 54 are electrically connected to the electrode body 60 accommodated in the case body 20. The attachment structure of each terminal 52, 54 is not particularly limited, and can be the same structure as a conventional battery. For example, in the present embodiment, one end of the positive electrode terminal 52 is formed at one end in the axial direction of the electrode body 60 (or the winding axis direction if the electrode body 60 is a wound type). By being connected to the body 63, it is electrically connected to the positive electrode of the electrode body 60. The other end of the positive electrode terminal 52 protrudes from the surface side of the lid 30. Similarly, one end of the negative electrode terminal 54 is connected to the negative electrode of the electrode body 60, and the other end protrudes from the surface side of the lid body 30. The protruding terminals 52 and 54 are fixed to the lid body 30 by, for example, a nut 58 or the like. In addition, since the attachment structure itself of the connection terminal of positive / negative polarity does not characterize this invention, more detailed description is abbreviate | omitted.

  The material of the lid 30 is preferably the same material as the case main body 20 described above, but may be a material different from the case main body 20. As a method of forming the lid 30, typically, a plate material made of a metal material (typically aluminum or an alloy material thereof) that can be employed for forming the case body 20 is used, for example, pressing or the like. The shape can be formed as described above. A preferable plate pressure when formed on the lid 30 is preferably 0.3 mm to 1 mm, more preferably 0.3 mm to 0.7 mm, and particularly preferably about 0.5 mm.

Next, the electrode body 60 according to the present embodiment will be described. The electrode body 60 includes a positive electrode sheet 62 having a positive electrode active material layer on the surface of a long sheet-like positive electrode current collector 63, and a negative electrode active material layer on the surface of a long sheet-like negative electrode current collector (not shown). A negative electrode sheet (not shown) and a long sheet-like separator 66. Two separators 66 are arranged between the positive electrode sheet 62 and the negative electrode sheet in the order of the positive electrode sheet 62, the separator 66, the negative electrode sheet, and the separator 66. The resulting wound body is formed into a flat shape that can be accommodated in the case body 20 by crushing and ablating the obtained wound body from the side surface direction (that is, the direction orthogonal to the winding axis direction). ing.
In the wound positive electrode sheet 62, the positive electrode current collector 63 is exposed without being provided with the positive electrode active material layer at one end portion along the longitudinal direction thereof, while the wound negative electrode sheet is also The negative electrode current collector is exposed at one end along the longitudinal direction without being provided with the negative electrode active material layer. Thus, the exposed positive electrode current collector 63 is laminated at one end in the longitudinal direction (that is, the winding axis direction) of the electrode body 60, and the exposed negative electrode current collector is laminated at the other end. Yes.
Further, as described above, the positive electrode terminal 52 is bonded to the exposed portion where the positive electrode current collector 63 is laminated, and the negative electrode terminal 54 is bonded to the exposed portion where the negative electrode current collector is laminated. The positive electrode sheet 62 or the negative electrode sheet formed in the flat shape is electrically connected. As a joining method, a conventionally known method may be used. For example, various welding methods such as an ultrasonic welding method and a resistance welding method may be used. Although the wound electrode body has been described in the present embodiment, it may be a stacked electrode body and is not particularly limited.

The materials and members constituting the electrode body 60 as described above may be the same as those of the electrode body provided in the conventional lithium ion battery, and are not particularly limited. For example, as the positive electrode current collector 63 constituting the positive electrode sheet 62, a sheet material made of a metal having good conductivity can be used. For example, a conductive member made of aluminum or an alloy mainly composed of aluminum can be given. Moreover, as an electrode active material which is a main component of the positive electrode active material layer, one or more kinds of materials conventionally used in lithium ion batteries can be used without particular limitation. For example, a lithium-nickel composite oxide (an oxide containing lithium and nickel as constituent metal elements, in which a part of the nickel site is substituted with another metal element such as cobalt or aluminum. Include lithium transition metal composite oxides such as LiNiO ₂ ), lithium cobalt composite oxide (typically LiCoO ₂ ), and lithium manganese composite oxide (typically LiMn ₂ O ₄ ).
On the other hand, as the negative electrode current collector constituting the negative electrode sheet, for example, a sheet material (preferably copper foil) made of a metal such as copper can be used. Moreover, as an electrode active material which is a main component of the negative electrode active material layer, one or more kinds of materials conventionally used in lithium ion batteries can be used without particular limitation. For example, carbon materials such as graphite carbon and amorphous carbon can be used.
The positive electrode sheet 62 and the negative electrode sheet can be preferably prepared by applying a composition in which each of the electrode active materials is dispersed in an appropriate solvent on each current collector and drying the composition. In addition, a conductive material, a binder, a thickener, etc. can be added to the said composition as needed.

As a suitable sheet-like separator 66 used by being stacked between the positive electrode sheet 62 and the negative electrode sheet produced above, those made of a porous polyolefin-based resin such as polyethylene and polypropylene can be cited. When a solid electrolyte or a gel electrolyte is used as the electrolyte, there may be a case where a synthetic resin separator is unnecessary (that is, in this case, the electrolyte itself can function as a separator). As the constituent material of the positive electrode terminal 52, a metal material (preferably aluminum) of the same type as the positive electrode current collector 63 joined to the terminal 52 can be preferably used. On the other hand, as a constituent material of the negative electrode terminal 54, a metal material (preferably copper) of the same type as the negative electrode current collector bonded to the terminal 54 can be preferably used.
As described above, the case main body 20, the lid body 30, and the electrode body 60 are prepared (manufactured).

Next, although not intended to be particularly limited, one preferred embodiment of a method for constructing (manufacturing) the lithium ion battery 10 according to the present embodiment will be described with reference to FIGS. 4 to 5. To do.
First, the above-described configuration shown in FIGS. 1 and 2 (that is, a bottomed box shape having an opening 21 on the upper surface of the case, a horizontal opening end surface 24 on the upper surface 23 of the side wall 22, and the opening end surface) 24 and a case body 20 having an inclined surface portion 26 reaching the inner wall surface 25 of the side wall 22 is prepared (manufactured).
Next, the configuration shown in FIGS. 1 and 2 (that is, has a shape capable of closing the opening 21 of the case main body 20, and the opening end surface 24 when placed on the opening end surface 24). An outer edge portion 32 in contact with the lid body 30, a convex portion 34 formed on the back side of the lid body 30, and an inclined convex portion side surface 35 corresponding to the inclined surface portion 26 on at least a part of the side surface of the convex portion 34. A lid 30 having a configuration is prepared (produced).
Next, the electrode body 60 described above is prepared. Then, as shown in FIG. 2, for example, in the central portion in the vertical direction (vertical direction Q) of the stacked positive electrode current collector 63 formed at each end in the winding axis direction of the electrode body 60. The positive electrode terminal 52 is attached (as if the portion is crushed). Similarly, the negative electrode terminal 54 is attached to the negative electrode current collector.
Next, the flat electrode body 60 provided with the terminals 52 and 54 is accommodated in the flat case body 20. After housing the electrode body 60 in the case body 20, an appropriate amount of a lithium salt (supporting salt) such as LiPF ₆ is dissolved in an electrolyte solution (not shown) (for example, a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC)). In the case main body 20. Then, the positive and negative terminals 52, 54 protruding upward from the opening 21 of the case body 20 are inserted through terminal insulation holes (not shown) of the lid body 30 through the insulating member 56. A lid 30 is attached (placed) on the case body 20 to close the opening 21. At this time, the back side surface 32 a of the outer edge portion 32 of the lid body 30 is in contact with the opening end portion 24. Further, the inclined convex side surface 35 on the side surface of the convex portion 34 on the back side of the lid 30 is in contact with the inclined surface portion 26 on the side wall 22 of the case body 20, and the convex portion 34 enters the opening 21. Thus, the lid 30 is fitted to the case main body 20.

Next, in the case body 20 in which the lid body 30 is placed on the opening end surface 24, the contact portion between the case body 20 and the lid body 30, that is, the side wall 22 of the case body 20 and the outer edge portion of the lid body 30. A predetermined region including a boundary line with the outer periphery 32 is turned around from the side of the case body 20 and welded. As welding methods, laser welding using a coherent beam of monochromatic light, such as solid laser welding using a laser using a solid crystal such as YAG as a medium, gas laser welding using a gas such as carbon dioxide as a medium, or focusing is performed. Electron beam welding using an electron beam can be preferably employed.
Here, when the contact portion between the lid body 30 and the case main body 20 is welded from the side of the case main body 20 (that is, the outer wall surface 27 side of the side wall 22), a region melted by the welding is present. The region including the contact portion (boundary portion) between the back side surface 32a of the outer edge portion 32 and the open end surface 24 among the contact portions, and further including the contact portion between the inclined convex portion side surface 35 and the inclined surface portion 26. It is preferable to perform the welding at an output (in the case of laser welding, the laser intensity) of up to. By performing such welding, the bonding strength between the lid 30 and the case main body 20 can be increased. The reason is as follows. That is, as shown in FIG. 4A, the compressive stress generated in the melted portion 80 due to the heat shrinkage due to the welding is described with reference to the outer edge portion 32 of the boundary portion between the lid body 30 and the case body 20. The compressive stress 82 acting on both sides (that is, the lid 30 side and the case body 20 side) sandwiching the horizontal boundary portion between the back side surface 32a and the opening end surface 24 is in a direction toward the boundary portion along the vertical direction Q. Can occur. On the other hand, the compressive stress 84 acting on both sides of the boundary portion between the inclined surface portion 26 and the inclined convex portion side surface 35 can be generated in a direction toward the inclined boundary portion. Since the compressive stress 84 balances with the compressive stress 82 acting in the vertical direction Q, the lid 30 and the case body 20 are formed at the boundary portion between the lid 30 and the case body 20 in the non-melting portion on the inner wall surface 25 side. Even if a tensile stress is generated in a direction in which the case main body 20 can be separated, the balanced compressive stresses 82 and 84 can sufficiently counter the tensile stress. As a result, the lid 30 and the case main body 20 can be firmly joined, and such a joined state can be maintained for a long time. As shown in FIG. 4B, in the battery having a configuration not including the inclined surface portion 26 and the inclined convex portion side surface 35 as described above, the contact portion between the lid body 130 and the case main body 120 is defined as the case main body 120. Even if welding is performed from the side, a compressive stress 182 acting along the vertical direction Q such as the compressive stress 82 is generated in the melted portion 180, but the melted portion 180 is not melted on the non-melted portion on the inner wall surface side of the case body 120. Since a tensile stress 183 along the vertical direction Q can occur, it is difficult to firmly bond the lid 130 and the case body 120.

  When welding the lid 30 and the case body 20 according to the present embodiment from the side of the case body 20 as described above, the front side surface 32b of the outer edge portion 32 in the region on the surface side of the lid body 30. It is preferable to weld while pressing at least a region including an inclined concave side surface 37 extending from the peripheral edge of the concave portion 36 formed in a portion substantially corresponding to the convex portion 34 to the bottom surface 38 in the concave portion 36. By welding while pressing the region in this manner, the opening end surface 24 and the back side surfaces 32a of the outer edge portion 32, and the inclined surface portion 26 and the inclined convex portion side surface 35 can be reliably brought into contact with each other. Each contact site can be welded, and a predetermined region including the contact site can be reliably melted to join the lid 30 and the case body 20 more firmly.

  Further, when pressing the region on the surface side of the lid 30, it is preferable to use a holding jig 72. That is, in the pressing jig 72, the surface shape of the outer side surface 32 b of the lid body 30 and the inclined recess side surface 37 (on the surface that can come into contact with the surface side of the lid body 30 when the pressing jig 72 is pressed) That is, it is preferable that a surface shape corresponding to the uneven shape) is formed symmetrically to the surface shape of the front side surface 32b and the inclined concave side surface 37. The holding jig 72 having such a surface shape is placed on the region on the surface side of the lid 30 so as to match the corresponding surface shape, and the holding jig 72 (typically Is pressed downward (in the downward direction along the vertical direction Q), the horizontal contact portion between the opening end surface 24 and the front side surface 32b of the outer edge portion 32, and the inclined surface portion 26 and the inclined convex portion side surface 35 are inclined. Since the contact portion can be pressed simultaneously and uniformly with a force that is uniformly distributed, the region including the contact portion can be welded more firmly and easily.

  As described above, the contact portion between the lid 30 and the case main body 20 is joined and the opening 21 of the case main body 20 is sealed, whereby the battery 10 according to the present embodiment is completed.

  Next, a modified example of the battery 10 according to the present embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic cross-sectional view showing a main part of a modified example of the battery 10 according to the present embodiment. FIG. 7 is a schematic cross-sectional view showing a part of the process of welding the contact portion between the lid body 30 and the case main body 20 in the modified example of the battery 10 according to the present embodiment. In the modified example shown in FIG. 6, the inclined surface portion 26 in the side wall 22 of the case body 20 is a circular arc surface (typically a 1/4 arc surface) curved so as to swell toward the inner surface side of the case main body 20. In the point formed, it differs from the above-mentioned embodiment. In the embodiment in which the inclined surface portion 26 has such a curved surface shape, an arc surface corresponding to the inclined surface portion 26 (typically) is also present on at least a part of the side surface of the convex portion 34 formed on the back surface side of the lid 30. Specifically, a portion that becomes a 1/4 arc surface) is formed. Further, as shown in FIG. 6, the side surface of the convex portion 34 has the arc surface shape in the portion corresponding to the inclined surface portion 26 (that is, the inclined convex portion side surface 35), and the lid 30 is attached to the case main body. It is also preferable to have a vertical side surface 39 that can come into contact with the inner wall surface 25 of the side wall 22 when placed on the 20 open end surfaces 24. Further, on the surface side of the lid 30, the inclined concave side surface 37 of the concave portion 36 corresponding to the convex portion 34 also has an arcuate surface shape of a predetermined angle so as to substantially correspond to the inclined convex portion side surface 35. It is preferable. Since the shape of the front surface side of the lid body 30 is a shape corresponding to the back surface side, when the lid body 30 and the case main body 20 are welded from the side of the case main body 20, When the surface side is pressed, the lid body 30 and the case body 20 can be reliably brought into contact with each other and can be joined more firmly. Further, when performing such welding, as shown in FIG. 7, a presser jig having a surface shape which is symmetrical to the surface shape of the front side surface 32b of the outer edge portion 32 and the curved circular arc-shaped inclined concave portion side surface 37 is provided. It is preferable to use the tool 74 while pressing the front side surface 32 b and the inclined concave side surface 37.

Here, as the battery 10 according to this embodiment, four types of batteries having the following four dimensions (Example 1 to Example 4) were produced. In all of the four batteries, the lid 30 and the case main body 20 were joined by laser welding. The laser output intensity was the same for all four batteries.
In the battery according to Example 1, the case body 20 and the lid body 30 were respectively molded such that the wall thickness of the side wall 22 of the case body 20 and the plate thickness of the lid body 30 were both about 0.5 mm. The inclined surface portion 26 of the case body 20 is inclined from the vertical direction Q by an inclination angle θ of 45 °. The width of the side wall 22 of the opening end surface 24 in the wall thickness direction was about 0.2 mm to 0.3 mm. The dimensions of the back side surface 32a of the outer edge portion 32 of the lid 30 and the inclined convex portion side surface 35 are defined so as to correspond to the opening end surface 24 and the inclined surface portion 26, respectively. In addition, the dimensions on the surface side of the lid body 30 are defined so that the plate thickness is constant at about 0.5 mm at any part over the entire surface of the lid body 30.
Further, in the battery according to Example 2, the case body 20 and the lid body 30 were respectively molded such that the wall thickness of the side wall 22 of the case body 20 and the plate thickness of the lid body 30 were both about 0.5 mm. The inclined surface portion 26 of the case body 20 is inclined at an inclination angle θ of 30 ° from the vertical direction Q. The width of the side wall 22 of the opening end surface 24 in the wall thickness direction was about 0.2 mm to 0.3 mm. The dimensions of the back side surface 32a of the outer edge portion 32 of the lid 30 and the inclined convex portion side surface 35 are defined so as to correspond to the opening end surface 24 and the inclined surface portion 26, respectively. The dimensions on the surface side of the lid 30 were defined so that the plate thickness was constant at about 0.5 mm at any part over the entire surface of the lid 30.
In the battery according to Example 3, the case body 20 and the lid body 30 were respectively molded such that the wall thickness of the side wall 22 of the case body 20 and the plate thickness of the lid body 30 were both about 0.5 mm. The inclined surface portion 26 of the case body 20 was curved into a quarter arc surface shape having a curvature radius of about 0.2 mm to 0.3 mm so as to swell toward the inner surface side of the case body 20. The width in the wall thickness direction of the side wall 22 of the opening end surface 24 is about 0.3 mm to 0.2 mm, and the dimensions of the back side surface 32 a of the outer edge portion 32 and the inclined convex side surface 35 of the lid 30 are the same as those of the opening end surface 24. It was defined so as to correspond to each of the inclined surface portions 26. The dimensions on the surface side of the lid 30 were defined so that the plate thickness was constant at about 0.5 mm at any part over the entire surface of the lid 30.
In the battery according to Example 4, the case body 20 and the lid body 30 were respectively molded such that the wall thickness of the side wall 22 of the case body 20 and the plate thickness of the lid body 30 were both about 0.5 mm. The inclined surface portion 26 as described above was not provided on the upper surface 23 of the side wall 22 of the case body 20. For this reason, a vertical side surface corresponding to the inner wall surface 25 extending in the vertical direction Q is formed on the side surface on the back side of the convex portion 34 of the lid 30, and the inclined convex portion side surface 35 is not provided.

  With respect to the battery of Example 1 manufactured as described above, a test was conducted in which only the lid 30 joined to each other by welding was gripped and lifted with a predetermined load, and the lid 30 was peeled off from the case body 20. The load when the lid 30 was peeled off from the case body 20 was defined as the bonding strength between the lid 30 and the case body 20. The same test was performed on the batteries of Examples 2 to 4. As a result, in each of the batteries of Examples 1 to 3, the lid 30 and the case main body 20 are bonded with a bonding strength of 30% or more (preferably 50% or more) as compared with the battery of Example 4. I understood that. As a result, the inclined surface portion 26 formed on the side wall 22 of the case body 20 and the inclined convex portion side surface 35 corresponding to the inclined surface portion 26 on the side surface of the convex portion 34 formed on the back surface side of the lid 30. It turned out that the battery 10 provided with the inclined convex part side surface 35 has a remarkably excellent effect in the joint strength of the cover body 30 and the case main body 20 compared with the battery which does not comprise these.

  As described above, the battery 10 according to the present embodiment in which the lid 30 and the case body 20 can be firmly joined can be suitably used as a power source for a motor (electric motor) mounted on a vehicle such as an automobile. Accordingly, in the present invention, as schematically shown in FIG. 8, a plurality of such batteries 10 are arranged as single cells to construct an assembled battery 100, and a vehicle (typically, an automobile) provided with such an assembled battery 100 as a power source. In particular, an automobile equipped with an electric motor such as a hybrid car, an electric car, and a fuel cell car 1) can be provided.

  As described above, the present invention has been described with reference to the preferred embodiments. However, such description is not a limitation, and various modifications can be made. In addition, the type of battery is not limited to the above-described lithium ion battery, but batteries having various contents with different electrode body constituent materials and electrolytes, for example, lithium secondary batteries having a negative electrode made of lithium metal or lithium alloy, nickel metal hydride batteries, nickel cadmium It may be a battery or an electric double layer capacitor. Moreover, although the case main body 20 of the above-mentioned embodiment is shape | molded by the square shape (box shape) shape, it is not limited to this shape, For example, a cylindrical shape may be sufficient.

It is a typical perspective view which shows the external appearance of the battery which concerns on this embodiment. It is the II-II sectional view taken on the line of FIG. It is sectional drawing which shows typically the contact site | part of this cover body and case main body when a cover body is mounted on the opening end surface of a case main body. (A) It is sectional drawing which shows typically the fusion | melting part at the time of being welded from the case side to the contact site | part of the battery cover body and case main body which concern on this embodiment. (B) It is sectional drawing which shows typically the fusion | melting part at the time of welding to the contact part of a cover body and a case main body from the case side in the battery of a structure which does not have an inclined surface part in a case main body side wall. It is typical sectional drawing which shows a part of process of welding the contact part of a cover body and a case main body. It is typical sectional drawing which shows the principal part of the modification of the battery which concerns on this embodiment. It is typical sectional drawing which shows a part of process of welding the contact part of the cover body and case main body in the modification of the battery which concerns on this embodiment. It is a side view showing typically a vehicle provided with a sealed type battery concerning this embodiment.

Explanation of symbols

P Horizontal direction Q Vertical direction 1 Vehicle 10 Sealed battery 20 Case body 21 Opening portion 22 Side wall 23 Upper surface 24 Opening end surface 25 Inner wall surface 26 Inclined surface portion 27 Outer wall surface 30 Lid 32 Outer edge portion 32a Back side surface 32b Front side surface
34 convex portion 35 inclined convex side surface 36 concave portion 37 inclined concave side surface 38 bottom surface 52 positive electrode terminal 54 negative electrode terminal 56 insulating member 58 nut 60 electrode body 62 positive electrode sheet 63 positive electrode current collector 66 separator 72, 74 holding jig 100 assembled battery

Claims (9)

A case main body for accommodating the electrode body, and an opening for accommodating the electrode body formed on the upper surface of the case; and
A lid mounted on an opening end surface corresponding to an upper surface of a side wall of a case main body constituting a peripheral edge of the opening, and an outer edge portion contacting the opening end surface when the lid is mounted; and the lid A sealed battery including a lid having a convex portion formed on the back surface side of the projection and entering the inside of the opening when placed.
The case main body and the lid body have a predetermined region including a boundary line between the case main body side wall and the outer edge portion of the lid body in a state where the lid body is placed on the opening end surface from the side of the case. Are joined together by being melted by welding
Here, on the side wall of the case body constituting the periphery of the opening, an inner wall surface that forms the inner surface of the case body and extends in the vertical direction, and the opening end surface that forms the upper surface of the case body and extends in the horizontal direction An inclined surface portion extending from the horizontal opening end surface to the vertical inner wall surface is formed, and the side surface of the inclined convex portion corresponding to the inclined surface portion is at least the side surface of the convex portion. Formed in part,
The hermetically sealed battery is characterized in that the region melted by the welding extends beyond the opening end surface to a boundary portion between the inclined surface portion and the inclined convex portion side surface. On the surface side of the lid, a concave portion is formed in a portion substantially corresponding to the convex portion on the back surface side, and an inclined concave side surface extending from the periphery of the concave portion to the bottom surface in the concave portion is formed.
2. The sealed battery according to claim 1, wherein the inclined convex portion side surface and the inclined concave portion side surface are formed so as to be substantially parallel when viewed from a cross-section of the lid.   The sealed battery according to claim 1, wherein the inclined surface portion is inclined at an inclination angle of 30 to 60 ° from the vertical direction.   The width in the wall thickness direction of the side wall of the case main body at the opening end surface is defined as a length of 40 to 60% of the wall thickness of the side wall of the case main body. The sealed battery according to 1. Both the wall thickness of the side wall of the case body and the plate thickness of the lid body are in the range of 0.3 mm to 1 mm,
The sealed battery according to claim 1, wherein the inclined surface portion is inclined at an inclination angle of 30 to 50 ° from the vertical direction. Both the wall thickness of the side wall of the case body and the plate thickness of the lid body are in the range of 0.3 mm to 1 mm,
The inclined surface portion is an arc surface curved so as to swell toward the inner surface side of the case body,
5. The sealed battery according to claim 1, wherein a side surface of the inclined convex portion of the lid is curved in a circular arc shape having a curvature corresponding to the circular arc surface. A method for producing a sealed battery;
An opening formed on the upper surface of the case; an inner wall that forms an inner surface on a side wall that forms a periphery of the opening; and an opening end surface that forms an upper surface of the side wall and extends in the horizontal direction. Providing a case body, wherein an inclined surface portion extending from the horizontal opening end surface to the vertical inner wall surface is formed between the inner wall surface and the opening end surface;
An outer edge portion that comes into contact with the opening end surface when placed on the opening end surface, and a convex portion that is formed on the back surface side and enters the inside of the opening when placed. Providing a lid having a sloped convex portion side surface corresponding to the sloped surface portion formed on at least a part of the side surface of the convex portion;
Accommodating the prepared electrode body in the case body from the opening;
Placing the lid on the open end face; and
Joining a predetermined region including a boundary line between the side wall of the case main body and the outer edge of the lid by melting them by welding from the side of the case;
And
Here, at the time of the welding, at least the outer edge portion of the surface side of the lid, and the inclined concave side surface extending from the peripheral edge of the concave portion formed in a portion substantially corresponding to the convex portion to the bottom surface in the concave portion, , Welding while pressing the area containing
A method for manufacturing a sealed battery, wherein welding is performed so that a region to be melted by welding extends beyond the opening end surface to a boundary portion between the inclined surface portion and the inclined convex portion side surface.   The method for manufacturing a sealed battery according to claim 7, wherein a pressing jig having a surface shape symmetrical to the surface shape of the pressed region is used for the pressing.   A vehicle comprising the sealed battery according to any one of claims 1 to 6 or the sealed battery manufactured by the method according to claim 7 or 8.

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