JP2013041752A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a resin member on a lid from discoloring when a mating surface of the lid and a case body is laser welded and thereby providing a sealed battery having excellent appearance quality.SOLUTION: A sealed battery 10, where a mating surface 25 between a case body 21 and a lid 22 is located at the outer surface 22A side of the lid 22 and the mating surface 25 is laser welded, is provided. A terminal 40 connecting with an electrode body of the battery 10 is led out from a through hole of the lid 22 to the exterior and is separated from a lid outer surface 22A by an outer resin member 60. The outer resin member 60 is formed by a nonaromatic resin composition.

Description

  The present invention relates to a sealed battery in which an electrode body is accommodated in an outer case.

  A battery having a configuration in which an electrode body including a positive electrode and a negative electrode is sealed in an outer case is known. In one typical configuration of a battery having such a configuration, the exterior case includes a case main body having an opening and a lid body (typically, laser welding) welded to the opening. Patent document 1 is mentioned as technical literature regarding this kind of battery.

JP 2010-282847 A

  As shown in FIG. 11, the battery disclosed in Patent Document 1 has a terminal 40 drawn out from a through-hole (terminal lead-out hole) 242 of the lid 22, and the terminal 40 and the outer surface 22 </ b> A of the lid 22 are The outer resin member 60 is insulated by being separated. A joint (that is, a welded portion) 25 between the case main body (case main body) 21 and the lid body 22 is provided on the side of the lid body 22 (side surface side of the case main body 21).

  When the seam 25 is on the outer surface 22A side of the lid 22 as shown in FIG. 2, laser welding can be performed from one direction (the lid outer surface 22A side; This is advantageous from the standpoint of improving battery productivity. However, in the case of the battery having the structure in which the outer resin member 60 is arranged on the lid as shown in FIG. 2, the present inventor irradiates the seam 25 on the outer surface 22A side of the lid with laser and welds it. It has been found that there is an inconvenience that the member 60 turns blackish. Such discoloration is not preferable because it deteriorates the appearance quality of the battery.

  Therefore, the present invention has a terminal pulled out from the terminal lead-out hole of the lid, and has an outer resin member that separates the drawn terminal and the lid, and the lid is laser welded to the case body from the outer surface side. Another object of the present invention is to prevent the outer resin member from being discolored by welding in a sealed battery (typically a secondary battery).

  Conventionally, a polyphenylene sulfide resin (PPS) excellent in heat resistance and strength has been widely used as a material for forming a resin member disposed around a terminal lead hole of a battery (particularly a nonaqueous electrolyte secondary battery). Further, it is generally known that PPS and other aromatic resins tend to have higher heat resistance and strength than non-aromatic resins. As a result of various investigations on resins having resistance to discoloration (burning) caused by laser welding as described above, the present inventor unexpectedly has compositions based on non-aromatic resins instead of aromatic resins. It has been found that the discoloration can be effectively prevented by using (non-aromatic resin composition).

  The sealed battery provided by the present invention includes a case main body having an opening, an electrode body accommodated in the case main body, a lid fixed to the opening of the case main body, and an electrical connection to the electrode body. And an outer resin member that separates the terminal and the outer surface of the lid. The lid has a through hole (terminal lead hole), and the terminal is drawn out of the battery through the through hole. The joint between the lid and the case body is on the outer surface side of the lid, and the joint is laser welded. The outer resin member is formed of a non-aromatic resin composition. By using an outer resin member formed of a non-aromatic resin composition in this way, unlike the outer resin member made of an aromatic resin composition such as PPS, discoloration of the outer resin member due to laser welding is prevented. can do.

  Here, the non-aromatic resin composition refers to a composition based on a non-aromatic resin. Preferable examples of the non-aromatic resin include 6 nylon, 66 nylon, polyacetal, tetrafluoroethylene-perfluoroalkyl vinyl ether resin, polymethyl methacrylate, and the like. In a preferred embodiment, the non-aromatic resin composition as a whole is 100% by mass, and 80% by mass or more thereof is a non-aromatic resin (preferably one or two of the non-aromatic resins according to the preferred examples). Above).

  The technique disclosed herein can be preferably applied to a sealed battery formed by laser welding a lid body on which an outer resin member is previously arranged to a case body. Such a sealed battery, for example, produces a lid unit in which a terminal connected to the electrode body is integrated with the lid body via the outer resin member, and an outer surface of the lid body constituting the lid unit. The battery may be formed by laser welding a joint between the outer edge and the case body. In such a battery, it is particularly meaningful to apply the present invention to prevent discoloration of the outer resin member.

  As a preferable application object of the technology disclosed herein, the case body and the lid form a flat rectangular outer case, and the lid is used on one of the narrow surfaces thereof. Type batteries. In such a battery, since the lid has an elongated shape, the distance between the welded portion (that is, the joint between the lid and the case body) and the outer resin member tends to be small. Therefore, it is particularly meaningful to apply the present invention to prevent discoloration of the outer resin member.

  In a preferred embodiment of the sealed battery disclosed herein, the battery is a bolt having a head portion and a leg portion, and the leg portion is inserted into a bolt insertion hole provided in an outer end portion of the terminal. The bolt is further provided. The outer resin member has an attachment portion sandwiched between the outer surface of the lid surrounding the through hole and the terminal, and an extension portion extending along the outer end portion of the terminal. A bolt receiving hole for receiving the head portion of the bolt and restricting the rotation of the bolt is formed in the extension portion of the outer resin member. And the shape of the said bolt receiving hole and the said bolt head is a rectangular shape.

  According to such an embodiment, for example, a stress (a bolt head is applied to the bolt receiving hole of the outer resin member when the bolt is tightened while securing a seating area equivalent to a bolt having a general hexagonal head (hexagon bolt). The mechanical strength of the outer resin member can be improved with respect to the stress received when the rotation of the head is prevented by contacting the wall surface of the bolt receiving hole. Such improvement in mechanical strength can be achieved, for example, by increasing the thickness of the wall surrounding the bolt receiving hole (distance from the peripheral wall surface of the bolt receiving hole to the outer periphery of the outer resin member) for the long side of the rectangle. Can be done. As a result, discoloration of the outer resin member can be prevented, and a decrease in mechanical strength accompanying the formation of the outer resin member with a non-aromatic resin composition can be compensated. As described above, in a sealed secondary battery including a flat rectangular outer case, the bolt receiving hole and the bolt head are formed in a rectangular shape having a long side in the longitudinal direction of the lid. Is preferred.

  According to the present invention, there is also provided an assembled battery including any one of the batteries disclosed herein as a single battery and a plurality of the single batteries. The terminals of these unit cells are connected via a connecting member. In a preferred aspect, the unit cell is a sealed battery having the bolt, and the connecting member is formed on the outer side of the terminal by tightening a nut through a bolt leg through the bolt insertion hole of the connecting member. Fastened to the end. The assembled battery of this aspect is excellent in appearance quality because discoloration of the outer resin member is prevented, and has a seating area of the bolt (in other words, a terminal and a terminal) while ensuring a mechanical strength that can withstand the fastening pressure of the bolt. Since the fastening area with the connecting member can be widened, the connection resistance between the single cells can be low.

  In this specification, “secondary battery” includes a so-called storage battery such as a lithium ion secondary battery, a metal lithium secondary battery, a nickel metal hydride battery, and a nickel cadmium battery, and a storage element such as an electric double layer capacitor. It is. The “nonaqueous electrolyte secondary battery” refers to a battery provided with a nonaqueous electrolyte (typically, an electrolyte containing a supporting salt (supporting electrolyte) in a nonaqueous solvent). The “lithium secondary battery” refers to a secondary battery that uses lithium ions as electrolyte ions and is charged and discharged by the movement of lithium ions between the positive and negative electrodes. A secondary battery generally referred to as a lithium ion battery is a typical example included in the lithium secondary battery. The technology disclosed herein is typically applied to a sealed nonaqueous electrolyte secondary battery (for example, a lithium ion secondary battery).

  Any sealed battery (for example, a lithium ion secondary battery) disclosed herein is typically used in the form of a battery pack and can be preferably used as a power source mounted on a vehicle. For example, it is suitable as a power source (typically a drive power source) for a motor mounted on a vehicle such as an automobile equipped with an electric motor such as a hybrid vehicle or an electric vehicle. Therefore, according to the present invention, a vehicle (for example, an automobile) provided with any of the sealed batteries disclosed herein (which may be in the form of an assembled battery) is provided.

It is a fragmentary sectional view showing a sealed type battery concerning one embodiment. It is sectional drawing which expands and shows a part of FIG. It is a top view which shows the inner side resin member which concerns on one Embodiment. It is a top view which shows the outer side resin member which concerns on one Embodiment. It is a side view which shows the outer side resin member which concerns on one Embodiment. It is a disassembled perspective view which shows the cover body and terminal of a sealed battery which concern on one Embodiment. It is a reference view which shows an outer side resin member. It is a side view which shows a part of assembled battery which concerns on one Embodiment. It is a top view which shows a part of assembled battery which concerns on one Embodiment. It is a typical side view showing vehicles (cars) carrying a battery concerning one embodiment. It is a fragmentary sectional view showing the conventional sealed type battery.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this 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 more detail below, taking as an example the case where the present invention is mainly applied to a lithium ion secondary battery having a flat rectangular outer case. In addition, in the following drawings, the same code | symbol is attached | subjected to the member and site | part which have the same effect | action, and the overlapping description may be abbreviate | omitted. Moreover, the dimensional relationship (length, width, thickness, etc.) in each drawing does not necessarily reflect the actual dimensional relationship.

  As shown in FIGS. 1 and 2, the lithium ion secondary battery 10 according to the present embodiment includes a flat rectangular parallelepiped (that is, rectangular) outer case 20 and a predetermined battery constituent material (positive and negative current collectors). And a wound electrode body 30 including a sheet-like electrode, a separator, and the like each holding an active material for each of the positive and negative electrodes is housed together with an appropriate electrolytic solution (not shown).

<Exterior case>
The exterior case 20 includes a box-shaped (that is, a bottomed rectangular tube-shaped) case main body 21 in which one of the narrow surfaces in the flat rectangular parallelepiped shape is an opening 21A, and a lid 22 that closes the opening. . Specifically, the lid 22 is fitted into the opening 21A of the main body 21, and the lid 22 is welded to the main body 21 by laser welding the joint 25 between the outer edge of the outer surface 22A of the lid 22 and the main body 21 around the opening 21A. It is fixed to. As shown in FIG. 2, the laser welding is performed from a direction non-parallel to the lid outer surface 22A (that is, a direction crossing the outer surface 22A, typically above the seam 25 (upward in FIG. 2)). This is done by irradiating light. The angle θ formed by the laser irradiation direction and the outer surface 22A of the lid body is typically about 60 ° to 120 °, and usually about 75 ° to 105 ° (for example, 75 ° to 90 °). is there. If θ is too small, the laser light may be blocked by the outer resin member 60 and may not easily hit the joint 25. If θ is too large, the outer resin member 60 is likely to be heated by reflected light or the like of laser irradiation, and if it is severe, problems such as thermal deformation of the outer resin member 60 may occur.

  The material constituting the case 20 is the same as that used in a general lithium ion secondary battery as long as the joint (welded portion) 25 between the main body 21 and the lid 22 can be joined by welding. It can be used as appropriate. From the viewpoint of heat dissipation and the like, a case 20 in which substantially the entire main body 21 and lid 22 are made of metal (for example, aluminum, stainless steel (SUS), steel, etc.) can be preferably used. The technology disclosed herein can be preferably applied to a battery (for example, a lithium ion secondary battery) in which almost the entire main body 21 and lid 22 are made of aluminum. Aluminum has a higher thermal conductivity than SUS, etc. (heat easily escapes), so the energy required for laser welding tends to increase. According to the technology disclosed here, high energy is applied in this way. Even in the welding mode, discoloration of the outer resin member can be effectively prevented. In the battery 10 according to the present embodiment, the main body 21 and the lid body 22 are both made of aluminum.

  The outer shape of the lid 22 is a substantially rectangular shape that matches the shape of the opening 21A (the opening shape of the main body 21). The technique disclosed here is, for example, a battery in which the width of the lid 22 (the length of the short side in the substantially rectangular shape; see FIGS. 4 and 6) W0 is approximately 10 mm to 28 mm (preferably 10 mm to 15 mm). It can be preferably applied. Thus, in a battery in which the width W0 of the lid body 22 is relatively narrow, the distance D1 (see FIG. 4) from the outer edge of the outer resin member 60 to the joint (welded portion) 25 is shortened in the width direction of the lid body 22. Tend to. Therefore, it is particularly meaningful to apply the technique disclosed herein to prevent discoloration of the outer resin member 60. The lid body 22 in the present embodiment has a rectangular shape with a width (W0) of 12.5 mm and a length of 136 mm.

  Although not particularly limited, the thickness (plate thickness) of the lid body 22 may be, for example, about 0.3 mm to 2 mm (typically 0.5 mm to 2 mm). The thickness of the lid 22 may be 0.5 mm or more and less than 1.5 mm. Moreover, the thickness (plate thickness) of the main body 21 can be set to about 0.5 mm to 3 mm, for example, and is typically 1 mm to 3 mm. In the battery 10 according to the present embodiment, the plate thickness of the aluminum material forming the main body 21 is 0.4 mm, and the plate thickness of the aluminum material forming the lid 22 is 0.7 mm.

<Winded electrode body>
The wound electrode body 30 is accommodated in the case main body 21 in a posture in which the shaft lies sideways (that is, the direction in which the opening is positioned in the lateral direction with respect to the winding shaft). A positive electrode terminal 40 and a negative electrode terminal 80 are respectively connected to both ends of the winding shaft of the electrode body 30. These electrode terminals 40, 80 pass through positive electrode and negative electrode terminal lead holes (through holes) 242, 244 provided at one end and the other end in the longitudinal direction of the lid 22, respectively. It is pulled out from the inside. That is, in this embodiment, the positive and negative electrode terminals 40 and 80 are drawn out from the lid body 22 that forms one of the narrow surfaces (terminal lead-out surface) of the flat rectangular outer case 20. As shown in FIGS. 1, 2, and 6, the positive electrode terminal 40 has a configuration in which a positive electrode internal terminal 420 mainly located inside the case 20 and a positive electrode external terminal 460 mainly located outside the case 20 are connected. . The negative electrode terminal 80 also has a configuration in which a negative electrode internal terminal 820 and a negative electrode external terminal 860 formed in substantially the same shape as the positive electrode side are connected (see FIG. 1).

  When the internal pressure of the case 20 rises between the terminal lead holes 242 and 244 (in the present embodiment, approximately the center in the longitudinal direction of the terminal lead surface 22), the lid (terminal lead surface) 22 A safety valve 27 for releasing the internal pressure by communicating the inside and outside is provided. The safety valve 27 in the present embodiment is mainly composed of a metal (for example, aluminum) sheet attached so as to close the opening 246 of the lid 22, and the linear (for example, two sheets) provided on the sheet is provided. The thin wall portion (with the lower end of the Y-shape facing each other) receives the internal pressure of the case and breaks, so that the internal pressure can be released.

  The wound electrode body 30 includes a sheet-like positive electrode (positive electrode sheet) 32 and a negative electrode (negative electrode sheet) 34 in total of two sheet-like separators (separator sheets) as in the case of a wound electrode body of a normal lithium ion secondary battery. ) 36 and wound in the longitudinal direction, and the obtained wound body is pressed from the side surface direction and kidnapped. The positive electrode sheet 32 and the negative electrode sheet 34 are slightly shifted in the width direction, and are stacked in such a manner that one end in the width direction of the separator sheet 36 and one end in the width direction of the sheets 32 and 34 protrude from each other. It has been turned. As a result, one end of the wound electrode body 30 in the winding axis direction and one end in the width direction of the positive electrode sheet 32 are wound around the core portion 31 (that is, the positive electrode sheet 32, the negative electrode sheet 34, and the separator sheet). 32A (a portion where 36 is closely wound) and a portion 32A that protrudes outward (positive electrode sheet protruding portion) and a portion where one end in the width direction of the negative electrode sheet 34 protrudes outward from the wound core portion 31 (negative electrode) A sheet protruding portion) 34A is formed. These protruding portions 32A and 34A are typically portions where no electrode active material is held (active material layer non-forming portions).

The material and the member constituting the wound electrode body 30 may be the same as the electrode body provided in the conventional lithium ion secondary battery, and are not particularly limited. The positive electrode sheet 32 according to the present embodiment has a configuration in which a positive electrode active material layer is formed on a long positive electrode current collector (for example, an aluminum foil). As the positive electrode active material used for forming this positive electrode active material layer, one or more of materials conventionally used in lithium ion secondary batteries can be used without particular limitation. Preferable examples include lithium transition metal oxides such as LiNiO ₂ , LiCoO ₂ , and LiMn ₂ O ₄ . Moreover, the negative electrode sheet 34 according to the present embodiment has a configuration in which a negative electrode active material layer is formed on a long negative electrode current collector (for example, a copper foil). As the negative electrode active material used for forming this negative electrode active material layer, one or more of materials conventionally used in lithium ion secondary batteries can be used without particular limitation. Preferable examples include carbon-based materials such as graphite carbon and amorphous carbon, lithium transition metal oxides, lithium transition metal nitrides, and the like. Preferable examples of the separator sheet include those made of a porous polyolefin resin. In the present embodiment, aluminum foil is used as the positive electrode sheet 32, LiNiO ₂ is used as the positive electrode active material, copper foil is used as the negative electrode sheet, and natural graphite is used as the negative electrode active material.

<Electrode terminal>
The lower end 422A of the positive electrode internal terminal 420 is connected to the protruding portion 32A of the positive electrode sheet, for example, by ultrasonic welding. The internal terminal 420 is formed following the plate-shaped (strip-shaped) first lead portion 422 extending substantially perpendicularly from the lower end 422A to the lid body 22 and the upper end of the first lead portion, and substantially perpendicular to the upper end ( In FIG. 2, a plate-like second lead portion 424 that is bent and extends substantially parallel to the inner surface of the lid body 22 from the front side to the back side of the drawing, and substantially perpendicular to the battery outward direction from the center portion of the plate surface of the second lead portion. And a protruding portion 426 extending in the direction. The protruding portion 426 in the present embodiment is configured as a rivet portion, and is riveted by penetrating the rivet portion (for example, substantially cylindrical shape) through the terminal lead hole 242 and the through hole (rivet hole) 462A of the external terminal 460. The internal terminal 420 and the external terminal 460 are connected (fastened). As a constituent material of the positive-side internal terminal 420 and the external terminal 460, a metal material with good conductivity is preferable, and aluminum is typically used. The positive electrode internal terminal 420 and the positive electrode external terminal 460 of this embodiment are made of aluminum.

  On the other hand, the positive external terminal 460 includes a first connection portion 462 provided with a through-hole 462A through which the protruding portion 426 can be inserted before the riveting, and a center side in the longitudinal direction of the lid body 22 (that is, a safety valve). 2nd connection part 464 (equivalent to the outer side edge part of the positive electrode external terminal 460) formed in a step-like manner on the outside of the case 20. The second connecting portion 464 is formed with a bolt insertion hole 464A through which the leg portion 674 of the bolt 670 can be inserted, as well shown in FIG. A bolt leg portion 674 is passed through the bolt insertion hole 464A from the bottom to the top, and the leg portion 674 protruding upward from the second connection portion 464 is connected to the outside (may be another battery terminal, an external circuit, or the like). The connecting member 112 can be coupled (fixed) to the external terminal 460 by mounting the connecting member 112 and tightening the nut 113 (see FIGS. 8 and 9).

  In the riveting, the inner resin member 50 is sandwiched between the wall surface of the lid 22 surrounding the terminal lead hole 242 and the second lead portion 424, and the outer resin is further interposed between the wall surface and the first connection portion 462 of the external terminal. This is performed with the member 60 interposed therebetween. By such riveting, the positive electrode terminal 40 is fixed to the lid body 22, and the inner resin member 50 is compressed between the lid body 22 and the second lead portion 424 to seal the terminal lead hole 242.

<Inner resin member>
Hereinafter, the configuration and function of the inner resin member 50 will be described in detail. The inner resin member 50 has an attachment portion 520 provided with an opening 522 through which the protruding portion 426 of the internal terminal 420 is inserted. The mounting portion 520 insulates the internal terminal 420 (second lead portion 424) from the lid body 22 by sandwiching and compressing the portion surrounding the opening 522 between the lid body 22 and the second lead portion 424. At the same time, the terminal lead hole 242 is sealed. A recess 524 that can receive the second lead portion 424 of the internal terminal 420 from below (that is, the inside of the case) is formed on the lower surface (surface on the electrode body side) of the mounting portion 520. The recess 524 is formed such that the lower end surface of the second lead portion 424 is accommodated inside the recess 524. This makes it difficult for the outer periphery of the electrode body 30 to directly contact the second lead portion 424 (particularly, the outer edge, that is, the edge portion), thereby avoiding a situation in which the electrode body 30 is damaged due to the contact. In addition, the outer edges of the three sides of the second lead portion 424 excluding the center side of the lid body are covered with the outer peripheral wall of the recess 524, thereby further insulating the internal terminal 420 (second lead portion 424) and the case body 21. It can be done reliably.

<Outside resin member>
Next, the configuration and function of the outer resin member 60 will be described in detail. The outer resin member 60 includes an attachment portion 620 sandwiched between the wall surface of the lid body 22 surrounding the terminal lead hole 242 and the first connection portion 462 of the external terminal, the second connection portion 464 of the external terminal, and the lid body 22. And an extension 640 extending therebetween. The mounting portion 620 is inserted from the outside into the terminal lead hole 242 to prevent (insulate) the direct contact between the rivet portion 426 and the lid body 22, and the outer surface of the lid body 22 is formed following the cylindrical portion 622. And a plate portion 624 extending along the line. The first connection part 462 of the external terminal is arranged in accordance with the depression of the dish part 624.

  The extension portion 640 is formed with a bolt receiving hole 642 having a rectangular opening shape whose long side is the longitudinal direction of the outer resin member 60 (which coincides with the longitudinal direction of the lid body 22). In the secondary battery 10 according to the present embodiment, the rotation of the head 672 is inserted into the bolt receiving hole 642 (restriction of co-rotation is prevented), and the leg 674 protrudes through the bolt insertion hole 464A. And a bolt 670 arranged (attached).

  The outer resin member 60 is formed of a non-aromatic resin composition, that is, a composition based on a non-aromatic resin. Here, the non-aromatic resin refers to a resin having no aromatic ring (typically a benzene ring), and preferred specific examples include aliphatic polyamides (6 nylon (PA6), 66 nylon (PA66), etc.), Examples include polyacetal (POM), tetrafluoroethylene-perfluoroalkyl vinyl ether resin (PFA), and methacrylic resin (typically polymethyl methacrylate (PMMA)). The non-aromatic resin composition may include any one of these non-aromatic resins, or may include two or more. It is preferable to use a resin composition having a heat-resistant temperature of 150 ° C. or higher (more preferably 250 ° C. or higher) based on a deflection temperature measurement (0.45 MPa) method. The outer resin member 60 according to the present embodiment is made of any one of PA66, POM, PFA, and PMMA.

  By using the outer resin member 60 made of such a material, when a conventional outer resin member made of PPS is used, the resin member is turned blackish by laser welding the joint 25 between the lid 22 and the case body 21. Even if the battery has a shape, discoloration of the outer resin member 60 due to the laser welding can be effectively prevented. Therefore, a higher quality battery can be manufactured with higher productivity.

  The technology disclosed herein can be preferably applied to a battery in which the minimum distance from the outer edge of the outer resin member 60 to the welded portion (the joint 25 between the lid 22 and the main body 21) is 5 mm or less (for example, 3 mm or less). . The application effect is particularly great in a battery having the distance of 2 mm or less (eg, 0.5 to 2 mm). In the present embodiment, in the width direction of the lid body 22, the distance D <b> 1 from the outer edge of the outer resin member 60 to the welded portion 25 is 1 mm. Moreover, about the longitudinal direction of the cover body 22, the distance D2 from the outer edge of the outer side resin member 60 to the welding part 25 is 2.8 mm. In addition, in a battery manufactured (welded) in a mode in which the minimum distance between the laser beam trajectory and the outer resin member 60 is in the above numerical range, the application effect of the technique disclosed herein can be exhibited particularly well.

The content ratio C _NA of the non-aromatic resin in the non-aromatic resin composition is typically 70% by mass or more (that is, C _NA ≧ 70% by mass), preferably C _NA ≧ 80% by mass ( Typically, C _NA > 80 wt%, more preferably C _NA ≧ 90 wt% In other words, the aromatic resin content ratio _CAR in the non-aromatic resin composition is typically 30 mass% or less (i.e. _{C AR} ≦ 30 wt%), preferably _{C AR} ≦ 20 wt%, more preferably _{C AR} ≦ 10 wt% _{.C AR} ≦ 5% by weight, which may be a _{.C AR} In a preferred embodiment, the outer resin member 60 is formed from a non-aromatic resin composition that does not substantially contain an aromatic resin. For example, In the infrared spectroscopy (IR) spectrum obtained by spectroscopic optical measurement, an outer resin member made of a non-aromatic resin composition in which no peak derived from the benzene ring is observed is preferable.

  Moreover, the kind of resin contained in the resin composition constituting the outer resin member 60 is specified by applying general analysis techniques such as IR spectrum analysis and pyrolysis gas chromatography in combination as necessary. Can do. Moreover, when the resin composition which comprises the outer side resin member 60 contains several resin, the compounding ratio of those resin can be grasped | ascertained from the said analysis result and specific gravity of an outer side resin member.

  Non-aromatic resins as described above tend to have lower mechanical strength than aromatic resins. Therefore, in this embodiment, a bolt having a rectangular head 672 instead of a general hexagonal shape is employed as the bolt 670. The outer resin member 60 is provided with a rectangular bolt receiving hole 642 corresponding to the shape of the bolt head 672 so that the long side thereof is in the longitudinal direction of the outer resin member 60. Advantages of such a configuration will be described below. That is, when the terminal 40 (external terminal 460) and the connection member 112 are fastened using the bolt 670 as shown in FIGS. 8 and 9, in order to reduce the connection resistance, the area of the seat surface of the bolt 670 ( It is advantageous to increase the area of the head 672. According to the bolt receiving hole 642 having the shape and arrangement as shown in FIG. 4, the bolt receiving hole 642 has the same seating area as that of the hexagonal bolt receiving hole 642 as shown in FIG. A wider width W1 to the outer edge of the outer resin member 60 can be secured. Therefore, even when a non-aromatic resin composition is used as the constituent material of the outer resin member 60, the area of the seating surface of the bolt 670 is increased to reduce the connection resistance, while preventing the rotation of the bolt 670 and other external forces. Thus, the outer resin member 60 having sufficient mechanical strength can be realized.

  Such a reduction in connection resistance can be achieved by using a battery (such as a battery for assembled batteries or a plurality of such batteries) that has a strong demand for high output (rapid discharge) such as a battery for a vehicle drive source (for example, a lithium ion secondary battery). It can be an assembled battery that is connected). In addition, since it is preferable to increase the cross-sectional area of the terminal in a high output battery, the distance from the outer edge of the outer resin member 60 to the welded portion 25 tends to be shortened. Also from this point, the present invention can be particularly preferably applied to a battery for a vehicle drive source.

  In addition, as a constituent material of the inner side resin member 50, the various resin composition which shows tolerance with respect to the electrolyte solution to be used can be selected suitably, and can be used. For example, a resin composition based on a resin such as polyphenylene sulfide resin (PPS), polyimide resin, polyamideimide resin, polyetheretherketone resin (PEEK), polyetherketoneketone resin (PEKK), polyethersulfone resin (PES), etc. A thing can be preferably employed. Further, the inner resin member 50 may be formed of the same resin composition as that of the outer resin member 60. The inner resin member 50 according to the present embodiment is formed of PPS.

  The structure of the negative electrode side (the outer shape of the negative electrode terminal 80 and its lead structure, etc.) in the battery 10 of the present embodiment is substantially the same as that of the positive electrode side except for the material of the negative electrode terminal 80. That is, one end of the negative electrode terminal 80 is connected to the negative electrode sheet protruding portion 34A of the electrode body 30 by, for example, resistance welding. The negative electrode terminal 80 includes a negative electrode internal terminal 820 and a negative electrode external terminal 860 formed in substantially the same shape as the positive electrode internal terminal 420, and a protruding portion (rivet portion) of the internal terminal 820 is a first connection portion of the external terminal 860. The terminals 820 and 860 are connected by riveting. The riveting is performed by sandwiching the inner resin member 50, the lid body 22, and the outer resin member 60 between the terminals 820 and 860 as in the positive electrode side. The external terminal 860 is formed in a staircase shape having a first connection portion and a second connection portion. Bolts 670 are installed in the bolt insertion holes provided in the second connection portion from the bottom to the top, and are configured so that the connection member 112 for external connection can be coupled (fixed) to the leg portion 674. Yes. As a constituent material of the internal terminal 820 and the external terminal 860 on the negative electrode side, a metal material having good conductivity is preferable, and copper is typically used. The negative electrode internal terminal 820 and the negative electrode external terminal 860 of this embodiment are made of copper. The material and shape of the inner resin member 50 and the outer resin member 60 are the same as those on the positive electrode side.

<Battery manufacturing method>
The lithium ion secondary battery 10 having such a configuration can be suitably manufactured (constructed) generally by the following procedure, for example. That is, the lid body 22 having the above-described configuration is prepared, and the inner resin member 50 is set on the inner side surface, and the outer resin member 60 and the positive electrode external terminal 460 are set on the outer side surface. At this time, the head 672 of the bolt 670 is accommodated in the bolt receiving hole 642 of the outer resin member 60, and the external terminal 460 is arranged from above. The protruding portion 426 of the positive electrode internal terminal 420 is protruded outward through the terminal extraction hole 424, the outer resin member 60 and the external terminal 460, and the protruding portion is riveted, whereby the positive electrode inner terminal 420 has a positive electrode in the terminal extraction hole 424. A terminal 40 is attached. Similarly to the positive electrode side, the negative electrode terminal 80 is attached to the terminal lead hole 244 of the lid 22. In this manner, a lid-terminal assembly in which the electrode terminals 40, 80 and the lid body 22 are integrated is obtained.

  Next, the positive electrode terminal 40 and the negative electrode terminal 80 are joined (for example, welded) to both ends in the axial direction of the wound electrode body 30 configured as described above. As a result, a lid unit (lid body-terminal-electrode body assembly) in which the lid body-terminal assembly and the electrode body 30 are integrated is obtained. Then, the lid body 22 is attached to the opening so that the electrode body 30 is housed from the opening of the case body 21, and the seam 25 between the lid body 22 and the case body 21 is laser-welded.

The laser welding conditions are not particularly limited as long as the lid body 22 and the case main body 21 can be joined in an airtight manner by welding. For example, as a laser beam to be used, a YAG laser, a fiber laser, a carbon dioxide gas laser, a DOE laser, an LD laser, or the like can be appropriately employed. Either continuous oscillation (CW) or pulse oscillation can be used. From the viewpoint of improving productivity, CW oscillation that facilitates increasing the welding speed is advantageous. In general, welding by CW oscillation (typically on the molten metal so that the molten portion gradually moves along the joint 45 by melting the adjacent portion using heat conduction from the molten metal). In this embodiment, the amount of energy applied is increased compared to welding by pulse oscillation, and therefore it is particularly meaningful to apply the present invention to prevent discoloration of the outer resin member. is there. The technique disclosed here can be preferably applied, for example, when the lid 22 and the main body 21 are laser-welded under the condition of an energy density of 0.2 to 100 kW / mm ² . Moreover, it can apply preferably, when the cover body 22 and the main body 21 are laser-welded on the conditions of welding speed 2-10m / min.

Thereafter, an electrolytic solution is injected into the case 20 from a liquid injection hole 28 provided in the lid 22. As the electrolytic solution, the same non-aqueous electrolytic solution conventionally used for lithium ion secondary batteries can be used without any particular limitation. In this embodiment, an electrolytic solution in which LiPF ₆ is contained in a mixed solvent of ethylene carbonate and diethyl carbonate (for example, a mixed solvent having a volume ratio of about 1: 1) at a concentration of about 1 mol / liter is used. Thereafter, the sealing cap 29 is attached to the liquid injection hole 28 (for example, welding) to seal the case 20. In this way, the lithium ion secondary battery 10 can be manufactured (constructed).

<Battery assembly>
Next, a configuration example of a battery pack including a plurality of the single cells, with the lithium ion secondary battery 10 having such a configuration as a single cell, will be described. As shown in FIGS. 8 and 9, the assembled battery 100 includes a plurality of (typically 10 or more, preferably about 10 to 30, for example, 20) lithium ion secondary batteries (unit cells) 10. The wide surfaces of the case 20 are arranged in the facing direction (stacking direction) while being inverted one by one so that the positive terminals 40 and the negative terminals 80 are alternately arranged. A cooling plate (not shown) having a predetermined shape is sandwiched between the arranged cells 10. The cooling plate functions as a heat radiating member for efficiently dissipating heat generated in each unit cell 10 during use, and introduces a cooling fluid (typically air) between the unit cells 10. It has a possible shape (for example, a shape in which a plurality of parallel grooves extending vertically from one side of the rectangular cooling plate to the opposite side are provided on the surface). A cooling plate made of metal having good thermal conductivity or lightweight and hard polypropylene or other synthetic resin is suitable.

  As shown in FIG. 9, a pair of end plates (constraint plates) 118 are disposed at both ends of the unit cell 10 and the cooling plate arranged as described above (FIG. 9 shows only one end side of the arrangement. Yes.) The arranged cells 10 and the cooling plate are constrained so as to apply a predetermined restraining pressure by a fastening restraining band (not shown) attached so as to bridge between both end plates. In addition, between the adjacent unit cells 10, one positive terminal 40 and the other negative terminal 80 are electrically connected by a connecting member (bus bar) 112. More specifically, the through holes provided at both ends of the connecting member 112 are respectively passed through the bolt leg portions 674 protruding from the external terminals of the adjacent unit cells 10, and the nut 113 is tightened from above, so that The other negative electrode terminal 80 can be electrically connected. Thus, the assembled battery 100 of the desired voltage is constructed | assembled by connecting each cell 10 in series. Although FIG. 9 shows an example in which the cells 10 and the cooling plates are arranged in a row, the cells 10 and the cooling plates may be arranged in two rows or three or more rows.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to the specific examples.

  The lithium ion secondary battery (unit cell) according to the above-described embodiment was constructed according to the above-described procedure. As the outer resin member, one obtained by injection molding a molding material having each resin composition shown in Table 1 by a conventional method was used. The presence or absence of discoloration of the outer resin member due to laser welding of the lid and the case under the following conditions was visually evaluated. The results are also shown in Table 1.

[Welding conditions]
Laser used: Fiber laser (wavelength: 1060 to 1070 nm)
Output: 2.8kW
Oscillation method: Continuous oscillation (CW)
Beam diameter: 0.8mm diameter
Irradiation angle θ: 89 degrees Minimum distance between laser beam trajectory and outer resin member: 1.0 mm
Energy density: 6 kW / mm ²
Welding speed: 8m / min

  As shown in Table 1, the outer resin member 60 (Example 1 to Example 4) made of non-aromatic resin has a common feature that no discoloration due to laser welding is observed regardless of the type of resin. It was confirmed to have. On the other hand, the outer resin member 60 (Example 5 to Example 9) made of an aromatic resin and the outer resin member 60 (Example 10, Example) made of a resin composition having a blending ratio of the aromatic resin of 40% by mass or more. In 11), it was confirmed that any of the resins was discolored by laser welding regardless of the type of resin.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible.

  The sealed battery according to the present invention (typically a secondary battery, for example, a lithium ion secondary battery) can be suitably used as a power source for a motor (electric motor) mounted on a vehicle such as an automobile. Therefore, as another aspect of the present invention, for example, as schematically shown in FIG. 10, the battery 10 (typically, a battery pack 100 formed by connecting a plurality of the batteries 10 in series) is driven. A vehicle (typically an automobile such as a hybrid automobile, an electric automobile, etc.) 1 provided as a power source for a vehicle is provided.

1 Automobile (vehicle)
10 Lithium ion secondary battery (sealed battery)
20 exterior case 21 case body 22 lid (terminal lead surface)
242,244 Through hole (terminal lead hole)
25 seam (welded part)
30 wound electrode body (electrode body)
40 Positive terminal (terminal)
420 Positive electrode internal terminal 426 Protruding part (rivet part)
460 Positive external terminal 462 First connection 464 Second connection (outer end)
464A Bolt insertion hole 50 Inner resin member 60 Outer resin member 620 Mounting portion 622 Tube portion 624 Plate portion 640 Extension portion 642 Bolt receiving hole 670 Bolt 672 Head 674 Leg portion 80 Negative electrode terminal (terminal)
100 assembled battery 112 connecting member (bus bar)

Claims (6)

A sealed battery:
A case body having an opening;
An electrode body housed in the case body;
A lid body fixed to the opening of the case body and having a through hole;
A terminal electrically connected to the electrode body and drawn out of the battery through the through hole of the lid; and
An outer resin member separating the terminal and the outer surface of the lid;
With
The joint between the lid and the case body is on the outer surface side of the lid, and the joint is laser welded,
The battery, wherein the outer resin member is formed of a non-aromatic resin composition.   80% by mass or more of the non-aromatic resin composition is composed of at least one selected from 6 nylon, 66 nylon, polyacetal, tetrafluoroethylene-perfluoroalkyl vinyl ether resin, and polymethyl methacrylate. Item 6. The battery according to Item 1.   A lid unit in which a terminal connected to the electrode body is integrated with the lid body via the outer resin member is manufactured, and an outer edge of the lid body constituting the lid unit is aligned with the case body. The battery according to claim 1, wherein the eye is laser welded. The case main body and the lid form a flat rectangular outer case,
The battery according to claim 1, wherein the lid constitutes one of the narrow surfaces of the exterior case. The battery further includes a bolt having a head portion and a leg portion, the bolt being disposed by inserting the leg portion into a bolt insertion hole provided in an outer end portion of the terminal,
The outer resin member has an attachment portion sandwiched between the outer surface of the lid body surrounding the through hole and the terminal, and an extension portion extending along the outer end portion of the terminal,
A bolt receiving hole for receiving the head portion of the bolt and restricting the rotation of the bolt is formed in the extension portion of the outer resin member,
The battery according to claim 1, wherein the bolt receiving hole and the bolt head have a rectangular shape. A battery pack comprising the battery according to claim 5 as a single battery,
A plurality of the cells;
A connection member for connecting the terminals of those single cells,
The assembled battery, wherein the connecting member is fastened to an outer end of the terminal by tightening a nut through a leg of the bolt into a bolt insertion hole of the connecting member.

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