阅读说明：本技术 非水电解质二次电池 (Nonaqueous electrolyte secondary battery ) 是由 梅村幸司 于 2020-11-25 设计创作，主要内容包括：本发明涉及具备具有正极和负极的电极体、非水电解质及电池壳体的非水电解质二次电池。电池壳体具备具有开口部且收容电极体和上述非水电解质的壳体主体和堵住开口部的盖体。盖体具备板状的盖主体、在电池壳体的内压变得比预先确定的开阀压大时开放的阀部及被设定为比阀部的上述开阀压大的开放压的气体释放部。(The present invention relates to a nonaqueous electrolyte secondary battery including an electrode body having a positive electrode and a negative electrode, a nonaqueous electrolyte, and a battery case. The battery case includes a case main body having an opening and housing the electrode assembly and the nonaqueous electrolyte, and a lid body closing the opening. The lid body includes a plate-shaped lid body, a valve portion that opens when the internal pressure of the battery case becomes greater than a predetermined valve opening pressure, and a gas release portion that is set to an opening pressure greater than the valve opening pressure of the valve portion.)

1. A nonaqueous electrolyte secondary battery is characterized by comprising:

an electrode body having a positive electrode and a negative electrode;

a non-aqueous electrolyte; and

a battery case,

wherein the battery case includes:

a case main body having an opening and configured to house the electrode body and the nonaqueous electrolyte; and

a cover body configured to close the opening portion,

the lid body is provided with:

a plate-shaped cover main body;

a valve unit configured to open when the internal pressure of the battery case becomes greater than a predetermined valve opening pressure; and

the gas release portion is configured to have an opening pressure higher than the valve opening pressure of the valve portion.

2. The nonaqueous electrolyte secondary battery according to claim 1,

the lid body further includes a welding projection provided at a peripheral edge of the gas release portion and configured to be fitted with a sealing cap.

3. The nonaqueous electrolyte secondary battery according to claim 2,

the welding projection and the gas releasing portion are provided on the same member.

4. The nonaqueous electrolyte secondary battery according to any one of claims 1 to 3,

the gas release portion is provided to the cap main body.

5. The nonaqueous electrolyte secondary battery according to claim 4,

in the gas release portion, a surface of the cover main body on a side opposite to the case main body is formed in an R shape.

6. The nonaqueous electrolyte secondary battery according to any one of claims 1 to 3,

the non-aqueous electrolyte is a non-aqueous electrolyte,

the lid further includes a liquid inlet configured to introduce the nonaqueous electrolytic solution into the case main body and a liquid inlet plug configured to close the liquid inlet,

the gas release part is arranged on the liquid injection plug.

7. The nonaqueous electrolyte secondary battery according to claim 6,

the filling tap has a stepped portion configured to protrude toward the case main body,

the gas release portion is provided at a portion of the stepped portion that protrudes toward the case main body.

8. The nonaqueous electrolyte secondary battery according to claim 6 or 7,

the gas release portion is provided to the liquid injection stopper and the cap main body, respectively.

Technical Field

The present invention relates to a nonaqueous electrolyte secondary battery.

Background

Nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries are widely used as portable power sources for personal computers, portable terminals, and the like, and as power sources for driving vehicles such as EVs (electric vehicles), HVs (hybrid vehicles), and PHVs (plug-in hybrid vehicles).

In applications such as power sources for driving vehicles, battery packs in which a plurality of nonaqueous electrolyte secondary batteries (single cells) are electrically connected to each other are widely used for increasing the output. An example of the battery pack includes: a pair of end plates arranged in a predetermined arrangement direction; a plurality of cells arranged between the pair of end plates and having electrode terminals for external connection; a flat plate-like spacer that sandwiches the plurality of cells from both sides in the arrangement direction; and a binding mechanism for applying a binding load between the pair of end plates from the arrangement direction. In the battery pack, electrode terminals of a plurality of single cells are electrically connected to each other by bus bars.

Disclosure of Invention

The battery pack mounted on the vehicle as a vehicle driving power source is removed from the vehicle and collected from the market, for example, when the vehicle is scrapped or replaced with a new battery pack. A battery pack recovered from the market often includes a reusable single cell. However, when the cell is used, gas may be generated inside the cell due to, for example, temperature deterioration or repetition of charge and discharge. As a result, battery bulges may occur in the unit cells, and the side surfaces in the arrangement direction may bulge convexly. Therefore, if a reusable unit cell is selected from the collected battery packs and assembled as a battery pack again, the position of the spacer with respect to the unit cell may be uneven. As a result, for example, the unit cells are assembled in an inclined state, and the size of the battery pack changes, or the vertical position of the electrode terminals is shifted, and it may be difficult to fasten the bus bars. Therefore, it is one of the problems to appropriately discharge the accumulated gas and reduce the battery bulge when the single cells are reused.

The invention provides a non-aqueous electrolyte secondary battery which can discharge accumulated gas to alleviate battery bulge and is easy to recycle.

The nonaqueous electrolyte secondary battery according to the aspect of the present invention includes an electrode body having a positive electrode and a negative electrode, a nonaqueous electrolyte, and a battery case. The battery case includes: a case main body having an opening portion configured to accommodate the electrode body and the nonaqueous electrolyte; and a lid configured to close the opening. The lid body includes: a plate-shaped cover main body; a valve unit configured to open when the internal pressure of the battery case becomes greater than a predetermined valve opening pressure; and a gas release portion configured to be set to an opening pressure higher than the valve opening pressure of the valve portion.

According to the above aspect, when the nonaqueous electrolyte secondary battery is reused, the gas release portion is artificially opened, whereby the gas accumulated in the nonaqueous electrolyte secondary battery can be discharged. This can alleviate battery bulge without opening the valve portion, for example. Therefore, the battery pack can be easily assembled again, and a nonaqueous electrolyte secondary battery that can be easily reused can be realized. In addition, the function of the valve section can be maintained even after reuse.

Further, international publication 2019/130501 is known as a related art document for discharging gas accumulated in a secondary battery. International publication No. 2019/130501 discloses a secondary battery including an exterior member having a flange and an electrode group disposed inside the exterior member. International publication 2019/130501 states that: when gas is generated inside the secondary battery, the flange of the exterior member is opened with an open hole to discharge the generated gas, thereby regenerating the secondary battery.

In the above aspect, the lid body may further include a welding projection provided at a peripheral edge of the gas release portion and configured to be fitted with a sealing cap. According to the above aspect, after the gas releasing portion is opened and the gas is discharged, the sealing cap and the welding projection are welded and joined to easily seal the gas releasing portion. This improves the accuracy and reliability of sealing the gas release portion. In addition, the convenience in recycling the nonaqueous electrolyte secondary battery can be improved.

In the above aspect, the welding protrusion and the gas releasing portion may be provided on the same member. By providing the welding projection and the gas releasing portion in the same member, the technique disclosed herein can be relatively easily realized.

In the above aspect, the gas releasing portion may be provided in the cap body. According to the above aspect, since only the design of the cover main body needs to be changed, the technology disclosed herein can be realized relatively easily.

In the above aspect, the cover body may have an R-shaped surface (i.e., a rounded surface) on a side facing the housing body in the gas release portion. According to the above aspect, for example, when the internal pressure of the nonaqueous electrolyte secondary battery rises due to the gas generated inside the battery case, the concentration of stress on the gas release portion can be alleviated. Thus, for example, in the normal use of the nonaqueous electrolyte secondary battery, the closed state of the gas release portion can be maintained at a high level.

In the above aspect, the nonaqueous electrolyte may be a nonaqueous electrolyte, the lid body may further include a liquid inlet configured to introduce the nonaqueous electrolyte into the case main body and a liquid inlet plug configured to close the liquid inlet, and the gas release portion may be provided in the liquid inlet plug. According to the above aspect, since only the design of the filling stopper needs to be changed, the technology disclosed herein can be realized relatively easily.

In the above aspect, the liquid filling plug may have a stepped portion configured to protrude toward the case main body, and the gas releasing portion may be provided at a portion of the stepped portion protruding toward the case main body. According to the above aspect, for example, when the internal pressure of the nonaqueous electrolyte secondary battery rises due to the gas generated inside the battery case, the concentration of stress on the gas release portion can be alleviated. Thus, for example, in the normal use of the nonaqueous electrolyte secondary battery, the closed state of the gas release portion can be maintained at a high level.

In the above aspect, the gas release portion may be provided in each of the liquid filling stopper and the cap body. According to the above aspect, the nonaqueous electrolyte secondary battery after once reuse can be easily reused. Therefore, the effects of the present invention can be exhibited at a higher level.

Drawings

The features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

fig. 1 is a vertical sectional view schematically showing the internal structure of a nonaqueous electrolyte secondary battery of embodiment 1.

Fig. 2 is a plan view schematically showing the nonaqueous electrolyte secondary battery of fig. 1.

Fig. 3 is a sectional view taken along line III-III of fig. 2.

Fig. 4 is a perspective view schematically showing a battery pack of embodiment 1.

Fig. 5A is a sectional view schematically showing a state where the gas release portion is opened.

Fig. 5B is a sectional view schematically showing a state where the gas release portion is resealed.

Fig. 6 is a plan view schematically showing the nonaqueous electrolyte secondary battery of embodiment 2.

Fig. 7 is a sectional view taken along line VII-VII of fig. 6.

Fig. 8A is a sectional view schematically showing a state where the gas release portion is opened.

Fig. 8B is a sectional view schematically showing a state where the gas release portion is resealed.

Fig. 9 is a plan view schematically showing the nonaqueous electrolyte secondary battery of embodiment 3.

Detailed Description

Embodiment 1

Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the accompanying drawings as appropriate. It is to be understood that the embodiments described herein are not intended to limit the technology disclosed herein. Matters other than those specifically mentioned in the present specification and matters necessary for implementation of the technology disclosed herein (for example, general structures and manufacturing processes of nonaqueous electrolyte secondary batteries and battery packs that do not characterize the technology disclosed herein) can be grasped as design matters by those skilled in the art based on the related art in this field. The technology disclosed herein can be implemented based on the content disclosed in the present specification and the technical common knowledge in the art.

In the following drawings, members and portions that obtain the same function are denoted by the same reference numerals, and redundant description may be omitted or simplified. The reference numerals U, D, F, Rr, R, L in the drawings mean up, down, front, rear, right, and left, respectively. Reference numeral X, Y, Z in the drawings denotes a front-rear direction, a left-right direction, and an up-down direction, respectively. In the following description, the front-rear direction is sometimes referred to as the thickness direction or the arrangement direction of the nonaqueous electrolyte secondary battery (unit cell), and the left-right direction is sometimes referred to as the width direction of the nonaqueous electrolyte secondary battery. However, these are merely directions for convenience of explanation, and the arrangement of the nonaqueous electrolyte secondary battery is not limited at all.

Nonaqueous electrolyte secondary battery

Fig. 1 is a longitudinal sectional view showing the internal structure of a nonaqueous electrolyte secondary battery 10 of embodiment 1. Fig. 2 is a plan view of the nonaqueous electrolyte secondary battery 10. The nonaqueous electrolyte secondary battery 10 is, for example, a secondary battery that can be repeatedly charged and discharged, such as a lithium ion secondary battery, a nickel metal hydride battery, and an electric double layer capacitor. The nonaqueous electrolyte secondary battery 10 includes an electrode body 20, a nonaqueous electrolyte not shown, and a battery case 30.

The electrode body 20 may be the same as the related art, and is not particularly limited. The electrode body 20 is a wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked in an insulated state with a strip-shaped separator interposed therebetween and wound around a winding shaft. The wound electrode assembly has a flat shape that can be housed in the battery case 30. The positive electrode and the negative electrode each include an active material capable of reversibly storing and releasing charge carriers. The positive electrode includes, for example, a lithium transition metal composite oxide as an active material. The negative electrode includes, for example, a carbon material as an active material.

The wound electrode body has a pair of winding flat portions and a pair of winding R portions interposed between the pair of winding flat portions in a cross section orthogonal to the winding axis. One of the pair of wound R portions of the wound electrode assembly is disposed below the battery case 30, and the other is disposed above the battery case 30. In addition, although the electrode body 20 is a wound electrode body here, a laminated electrode body in which rectangular positive electrodes and rectangular negative electrodes are alternately laminated in an insulated state may be used.

A positive electrode collector 12 is provided at the left end in the width direction Y of the electrode body 20. A positive electrode current collecting plate 12c is attached to the positive electrode current collecting unit 12. The positive electrode of the electrode body 20 is electrically connected to a positive electrode terminal 12T described later via a positive electrode current collector plate 12 c. In addition, a negative current collecting portion 14 is provided at the right end portion in the width direction Y of the electrode body 20. A negative current collecting plate 14c is attached to the negative current collecting portion 14. The negative electrode of the electrode assembly 20 is electrically connected to a negative electrode terminal 14T, which will be described later, via a negative electrode current collector plate 14 c.

The nonaqueous electrolyte may be the same as the related art, and is not particularly limited. The nonaqueous electrolyte here is a nonaqueous electrolyte that is liquid at room temperature (25 ℃). The nonaqueous electrolytic solution may also include a nonaqueous solvent and a supporting salt. The nonaqueous solvent may be an organic solvent such as a carbonate. The support salt may be, for example, a lithium salt including lithium ions as charge carriers. The nonaqueous electrolyte may be in a liquid state or a polymer state (gel state) in a temperature range in which the nonaqueous electrolyte secondary battery 10 is used (for example, a temperature range of-20 to +60 ℃). However, the nonaqueous electrolyte may be solid at room temperature (25 ℃). The nonaqueous electrolyte may be a solid electrolyte layer interposed between the positive electrode and the negative electrode, for example.

The battery case 30 is an outer case that houses the electrode body 20 and the nonaqueous electrolyte. The battery case 30 has a flat, square (rectangular parallelepiped) outer shape. However, the outer shape of the battery case 30 may be other shapes such as a cubic shape, a cylindrical shape, and the like. The battery case 30 includes a case main body 32 having an opening 32h, and a lid (sealing plate) 34 that closes the opening 32 h. The battery case 30 is integrated by bonding (e.g., welding) the lid 34 to the peripheral edge of the opening 32h of the case body 32. The battery case 30 is hermetically sealed (hermetically sealed).

The case body 32 is a bottomed box shape having an opening 32h at an upper side. The case main body 32 has a housing space 36 that houses the electrode body 20 and the nonaqueous electrolyte. The case body 32 includes a bottom surface 32b facing the cover 34, and a pair of short side surfaces 32n and a pair of long side surfaces (not shown) which are continuous from the bottom surface 32b and serve as side surfaces. The bottom surface 32b faces one of the pair of wound R portions of the electrode body 20. The long side face is opposed to the winding flat portion of the electrode body 20. The short side surface 32n and the long side surface are formed flat. The case body 32 is formed by drawing from, for example, 1 metal plate.

The case body 32 is made of, for example, a soft metal mainly containing 1 of aluminum, copper, magnesium, and brass (occupying 50 mass% or more). Among them, light-weight metals such as aluminum and aluminum alloys are preferable. The thickness (plate thickness) of the case body 32 is approximately 1mm or less, typically 0.5mm or less, and may be 0.3 to 0.5mm, for example, from the viewpoint of cost reduction and weight reduction. The battery case 30 made of a soft metal and/or thin as described above is easily deformed by the internal pressure. In the easily deformable battery case 30, battery bulge is particularly easily generated. Thus, a high effect is obtained by application of the technology disclosed herein.

The lid 34 is attached to the periphery of the opening 32h of the case body 32. As shown in fig. 1 and 2, the lid body 34 includes a lid main body 34b, a positive electrode terminal 12T, a negative electrode terminal 14T, a liquid filling plug 38, a valve portion (relief valve) 34v, and a gas release mechanism 34 g. However, the liquid injection plug 38 is not essential, and can be omitted when the nonaqueous electrolyte is solid, for example. The cover body 34b is a rectangular plate-shaped member. The cover main body 34b extends in the width direction Y. The cover main body 34b has a flat plate-like portion with a thickness La (see fig. 3). The cover body 34b is made of, for example, the same or different metal as the case body 32.

The positive electrode terminal 12T is provided at the left end portion in the width direction Y of the cap body 34 b. The positive electrode terminal 12T is electrically connected to the positive electrode of the electrode body 20. The negative electrode terminal 14T is provided at the right end portion of the cover main body 34b in the width direction Y. The negative electrode terminal 14T is electrically connected to the negative electrode of the electrode body 20.

As shown in fig. 1, the lid body 34b is provided with a pour hole 34 h. The liquid inlet 34h is a through hole that penetrates the lid body 34b in the thickness direction (vertical direction in fig. 1). The liquid inlet 34h is used for injecting the nonaqueous electrolytic solution into the storage space 36 which is the interior of the case main body 32. The liquid inlet 34h is used, for example, when the nonaqueous electrolyte secondary battery 10 is constructed or when the nonaqueous electrolyte secondary battery 10 is reused. The liquid inlet 34h is provided between the positive electrode terminal 12T and the negative electrode terminal 14T in the width direction Y. After the nonaqueous electrolytic solution is poured, a pouring plug 38 is attached to the pouring hole 34 h. The liquid filling plug 38 is made of metal such as aluminum or stainless steel. Thus, the pouring stopper 38 is integrated with the lid main body 34b, and the pouring hole 34h is hermetically sealed (sealed).

The valve portion 34v is a so-called safety valve. The valve portion 34v is provided between the positive electrode terminal 12T and the negative electrode terminal 14T in the width direction Y. In detail, the valve portion 34v is provided between the gas release mechanism 34g and the liquid filling stopper 38 in the width direction Y. The valve portion 34v is configured to be in an open state in which the interior of the battery case 30 communicates with the outside when the internal pressure of the housing space 36 becomes greater than a predetermined valve opening pressure during normal use of the nonaqueous electrolyte secondary battery 10, for example. When the valve portion 34v is in the open state, the gas accumulated in the storage space 36 is released to the outside of the nonaqueous electrolyte secondary battery 10, and the internal pressure of the nonaqueous electrolyte secondary battery 10 is released. The valve opening pressure of the valve portion 34v may be approximately 0.1 to 1.0MPa, for example, 0.3 to 0.5 MPa.

The valve portion 34v is formed in a thin shape thinner than the thickness La (see fig. 3) of the cap body 34 b. As shown in fig. 2, the valve portion 34v is mainly formed of a metal (e.g., aluminum) sheet v1 attached to the cover body 34 b. However, the valve portion 34v may be integrally formed with the cap body 34b to constitute a part of the cap body 34 b. The valve portion 34v may be a portion formed by thinning a part of the cap body 34 b.

The valve portion 34v of the present embodiment has a non-linear slit v2 provided in the metal piece v 1. The slit v2 has a shape in which the lower ends of the two Y-shapes face each other. However, the slit v2 may be linear, or may be non-linear other than Y-shaped, such as curved (e.g., semicircular, C-shaped, U-shaped, S-shaped), folded (e.g., L-shaped, N-shaped), intersecting linear (e.g., radial, cross), branched linear (e.g., H-shaped), and the like. When the internal pressure of the nonaqueous electrolyte secondary battery 10 exceeds the valve opening pressure, the notch v2 is cracked by receiving the internal pressure. Thus, the metal piece v1 is typically pushed out to the side away from the case main body 32 (upward in fig. 1).

Fig. 3 is a sectional view of the gas release mechanism 34g as viewed from the thickness direction X. The gas release mechanism 34g is integrally formed with the cap body 34b and constitutes a part of the cap body 34 b. As shown in fig. 2, the gas release mechanism 34g is provided between the positive electrode terminal 12T and the negative electrode terminal 14T in the width direction Y. Specifically, the gas release mechanism 34g is provided between the positive electrode terminal 12T and the valve portion 34v in the width direction Y. The gas release mechanism 34g is used when the nonaqueous electrolyte secondary battery 10 is reused. As shown in fig. 2 and 3, the gas release mechanism 34g includes a gas release portion 34n and a welding projection portion 34 p. However, the welding projection 34p is not essential and can be omitted.

The gas releasing portion 34n is a predetermined opening portion that is set in an open state in which the inside of the battery case 30 communicates with the outside by artificially applying an external force when the nonaqueous electrolyte secondary battery 10 is reused. The gas release portion 34n is configured to forcibly release the gas accumulated in the storage space 36 to the outside of the nonaqueous electrolyte secondary battery 10 to eliminate or alleviate the battery bulge. The gas releasing portion 34n is formed to be relatively thin compared with a portion (for example, a flat plate portion having a thickness La) of the cover main body 34b other than the gas releasing portion 34n so as to easily penetrate in the thickness direction (the vertical direction in fig. 1). By using the gas release portion 34n, the nonaqueous electrolyte secondary battery 10 can be easily opened when the nonaqueous electrolyte secondary battery 10 is reused.

The gas release portion 34n is set to an opening pressure greater than the valve opening pressure of the valve portion 34 v. Therefore, the gas release portion 34n is typically configured to maintain the closed state even when the valve portion 34v is in the open state. The gas release portion 34n is typically configured to maintain a closed state during normal use of the nonaqueous electrolyte secondary battery 10. From the foregoing, the minimum thickness (typically, the length in the up-down direction) of the gas releasing portion 34n can be larger than the valve portion 34v in cross section.

As shown in fig. 3, the gas releasing portion 34n is provided continuously from the cap main body 34b here. The gas releasing portion 34n includes a groove (notch) n1 provided on the outer surface (upper surface in fig. 3) of the lid main body 34b, and an R portion R1 provided on the surface (lower surface in fig. 3) inside the lid main body 34b, that is, the surface facing the case main body 32.

The groove portion n1 is typically a portion into which a sharp member is inserted when the nonaqueous electrolyte secondary battery 10 is reused. The groove portion n1 is provided on the outer surface of the lid main body 34b, and therefore functions as a rough target indicating the position of the gas release portion 34 n. The groove portion n1 is U-shaped in cross section. In cross section, the maximum depth (length in the vertical direction in fig. 3) of the groove portion n1 is smaller than the maximum height (length in the vertical direction in fig. 3) of the welding protrusion 34 p. As shown in fig. 2, the groove portion n1 is a straight line extending in the width direction Y in plan view. However, the groove portion n1 may be a dot or a non-linear shape. The length of the groove portion n1 in the width direction Y is shorter than the pouring hole 34 h. The length of the groove portion n1 in the width direction Y is shorter than the slit v2 of the valve portion 34 v.

The R section R1 has a larger area in plan view than the groove section n 1. The R1 is provided so as to surround the groove n1 in a ring shape with the groove n1 as the center. As shown in fig. 3, the length of the R portion R1 in the thickness direction X is longer than the groove portion n 1. Although not shown, the length of the R portion R1 in the width direction Y is longer than the groove portion n 1. Thus, for example, in the normal use of the nonaqueous electrolyte secondary battery 10, even if the internal pressure of the nonaqueous electrolyte secondary battery 10 rises, the stress concentration in the groove portion n1 can be alleviated. A dome-shaped space is maintained between the groove portion n1 and the housing space 36. The radius of curvature Lb of the R1 is equal to or smaller than the thickness La of the cover main body 34 b. When a sharp member is inserted into the groove n1 when the nonaqueous electrolyte secondary battery 10 is reused, the peripheral edge portion of the groove n1 of the lid main body 34b is pushed toward the case main body 32 (downward in fig. 3). At this time, if the dome-shaped space is maintained, the cover main body 34b pushed toward the case main body 32 side is less likely to interfere with the electrode body 20 housed in the case main body 32. Further, by setting the curvature radius Lb to the thickness La, the portion of the cover body 34b that is pushed toward the case body 32 side is suppressed to be small.

The welding projection 34p is used when the gas release portion 34n once provided in the open state is again in the closed state when the nonaqueous electrolyte secondary battery 10 is reused. As shown in fig. 3, the welding projection 34p projects toward a side (upper side in fig. 3) away from the battery case 30. The welding projection 34p is configured by, for example, bulging the peripheral edge of the gas release portion 34n in the lid body 34b and forming the welding projection to be thicker than the thickness La of the lid body 34 b. In cross section, the maximum height (the length in the vertical direction in fig. 3) of the welding protrusion 34p is greater than the maximum depth (the length in the vertical direction in fig. 3) of the groove n 1.

As shown in fig. 2, the welding projection 34p is provided so as to surround the periphery of the gas release portion 34 n. The welding projection 34p is continuously provided so as to annularly surround the gas release portion 34 n. However, the welding protrusions 34p may be provided in a plurality of island shapes with intervals so as to surround the gas release portion 34 n. In addition, the welding projection 34p may have a shape other than a ring shape in a plan view, for example, a polygonal frame shape.

The welding projection 34p is configured to be fitted to the sealing cap S (see fig. 5B) when the nonaqueous electrolyte secondary battery 10 is reused. The welding projection 34p also functions as a rough target indicating the position where the seal cap S is fitted. The welding projection 34p and the seal cap S are flush with each other by fitting the seal cap S along the inner edge of the welding projection 34 p. In this state, the welding projection 34p is welded to the sealing cap S, whereby the gas release portion 34n is hermetically sealed. This makes it possible to easily reseal the gas release portion 34n in the opened state. Therefore, the accuracy and reliability of the sealing of the gas release portion 34n are improved.

The nonaqueous electrolyte secondary battery 10 having the above-described structure can be used for various applications. The nonaqueous electrolyte secondary battery 10 is typically in the form of a battery pack 1 in which a plurality of nonaqueous electrolyte secondary batteries 10 are electrically connected, and can be preferably used as a power source (driving power source) for a motor mounted on a vehicle. The type of vehicle is not particularly limited, but typically includes automobiles such as a plug-in hybrid vehicle (PHV), a Hybrid Vehicle (HV), an Electric Vehicle (EV), and the like.

Battery pack

Fig. 4 is a perspective view of the battery pack 1. The assembled battery 1 includes a plurality of nonaqueous electrolyte secondary batteries (single cells) 10, a plurality of spacers 40, a pair of end plates 50A, 50B, and a plurality of straps 52. However, the spacer 40, the end plates 50A, 50B, and the binding band 52 are not essential, and a part or all of them can be omitted. The shape, size, number, arrangement, connection method, and the like of the cells 10 constituting the assembled battery 1 are not limited to those disclosed herein, and can be appropriately modified.

The plurality of cells 10 are arranged in the arrangement direction X in a state in which the positions of the positive electrode terminals 12T and the negative electrode terminals 14T are alternately reversed. In the assembled battery 1, the positive electrode terminal 12T and the negative electrode terminal 14T of the adjacent single cells 10 are electrically connected by the bus bar 18. By the foregoing, the battery packs 1 are electrically connected in series. The pair of long side surfaces of the plurality of single cells 10 face the spacers 40, respectively.

The spacer 40 is a heat dissipation member for dissipating heat generated in the single cell 10. The spacers 40 are disposed between the single cells 10 and the end plates 50A, 50B, respectively, in the arrangement direction X. The spacers 40 sandwich the cells 10 from both sides in the arrangement direction X. The spacer 40 is a plate-like member. The spacer 40 is made of resin such as polypropylene (PP) or Polyphenylene Sulfide (PPs), and is made of metal having good thermal conductivity.

The end plates 50A, 50B are disposed at both ends of the battery pack 1 in the arrangement direction X (the front-rear direction in fig. 4) of the single cells 10. The end plates 50A, 50B sandwich the plurality of single cells 10 and the plurality of spacers 40 in the arrangement direction X. A plurality of binding bands 52 are mounted across the pair of end plates 50A, 50B. A plurality of straps 52 are secured to the end plates 50A, 50B by a plurality of small screws 54. The plurality of straps 52 are attached to each other so as to apply a predetermined restraining pressure in the arrangement direction X. As described above, the battery assembly 1 is integrally held by applying a restraining load to the plurality of single cells 10 and the plurality of spacers 40 from the arrangement direction X. In the present embodiment, the end plates 50A and 50B, the plurality of tightening bands 52, and the plurality of screws 54 constitute a tightening mechanism. However, the binding mechanism is not limited thereto.

As described above, in the nonaqueous electrolyte secondary battery 10 according to embodiment 1, the gas release portion 34n is provided in the lid body 34 (specifically, the lid main body 34 b). As described above, when the nonaqueous electrolyte secondary battery 10 is reused, the operator can easily open the gas release part 34n and discharge the gas accumulated in the interior of the case main body 32 (i.e., the housing space 36). As a result, for example, battery swelling can be alleviated without opening the valve portion 34 v. Therefore, it is possible to realize a nonaqueous electrolyte secondary battery that can be easily reused and easily reused as the battery pack 1. Further, the function of the valve portion 34v is not impaired at the time of reuse, and the function can be maintained as it is even after reuse.

Method for manufacturing battery pack

A battery pack recovered from the market often includes a reusable single cell (nonaqueous electrolyte secondary battery 10). Hereinafter, a method of manufacturing the battery pack 1 by reusing (reusing) the nonaqueous electrolyte secondary battery 10 collected from the market will be described. The manufacturing method includes, for example, the following 4 steps: a sorting step of sorting reusable nonaqueous electrolyte secondary batteries 10; a gas release step of releasing the gas release part 34n of the nonaqueous electrolyte secondary battery 10 selected in the selection step to release the gas therein; a resealing step of sealing the gas releasing portion 34n opened in the gas releasing step to reseal the nonaqueous electrolyte secondary battery 10; and a battery pack construction step of constructing a battery pack 1 using the re-sealed nonaqueous electrolyte secondary battery 10. Among them, the gas release step and the resealing step can also be grasped as a method of reusing the nonaqueous electrolyte secondary battery 10. The production method disclosed herein may also include other steps as appropriate in addition to the above. For example, a step of adding a nonaqueous electrolyte to the nonaqueous electrolyte secondary battery 10 may be included between the sorting step and the step of constructing the battery pack.

In the sorting step, the nonaqueous electrolyte secondary battery 10 collected from the market is prepared. Next, the worker confirms, for example, the battery characteristics of the nonaqueous electrolyte secondary battery 10 by a predetermined test method (for example, a charge/discharge test). Then, the nonaqueous electrolyte secondary battery 10 having the battery characteristics equal to or more than a predetermined threshold is selected. In a preferred embodiment, the operator further determines whether or not a battery bulge has occurred in the nonaqueous electrolyte secondary battery 10 by a predetermined test method (for example, measurement of the size of the battery case 30). Then, the nonaqueous electrolyte secondary battery 10 having a battery swell equal to or greater than a predetermined threshold value is selected as "having a battery swell".

In the gas releasing step, first, the operator applies an external force to the gas releasing portion 34n of the nonaqueous electrolyte secondary battery 10 selected in the selecting step. For example, a sharp member is inserted into the groove portion n1 of the gas release portion 34n so as to penetrate the gas release portion 34 n. Thereby, the gas release portion 34n is opened. In addition, this step may be performed only for the nonaqueous electrolyte secondary battery 10 selected as "having a battery swell" in the selection step, for example. The step is preferably performed in a dry environment (e.g., an environment having a dew point temperature of-50 ℃ or lower).

Fig. 5A is a cross-sectional view of the gas release part 34n in an open state as viewed from the thickness direction X. In the nonaqueous electrolyte secondary battery 10, the groove portion n1 is broken, and the peripheral edge portion of the groove portion n1 of the lid main body 34b is pushed toward the case main body 32 (downward in fig. 5A). When the gas release portion 34n is opened, the gas accumulated in the battery case 30 is forcibly discharged to the outside. In one embodiment, a suction device according to the related art may be further attached to the gas release portion 34n in the open state to forcibly suck the fluid in the battery case 30. This eliminates the battery bulge of the nonaqueous electrolyte secondary battery 10.

In the resealing step, a sealing cap S is first prepared (see fig. 5B). The sealing cap S is typically a plate-like member. The outer shape of the seal cap S is the same as or smaller than the region surrounded by the welding protrusion 34 p. The sealing cap S is here a disc-shaped member. The thickness of the seal cap S is equal to the maximum height (the vertical length in fig. 5B) of the welding protrusion 34 p. Next, the operator fits the sealing cap S to the nonaqueous electrolyte secondary battery 10 opened in the gas release step along the inner edge of the welding projection 34 p. Thereby, the welding protrusion 34p and the seal cap S are coplanar. Next, the operator welds the entire circumference of the seal cap S to the welding projection 34 p. The method of welding is not particularly limited, but examples thereof include laser welding.

Fig. 5B is a cross-sectional view of the gas release portion 34n in a state after resealing as viewed in the thickness direction X. In the nonaqueous electrolyte secondary battery 10, a welded joint portion W is formed over the entire circumference of the sealing cap S, and the gas release portion 34n is hermetically sealed. This makes it possible to easily reseal the gas release portion 34n that has been opened in the gas release step.

In the battery pack constructing step, first, the worker alternately arranges the nonaqueous electrolyte secondary batteries (single cells) 10 and the spacers 40 in a predetermined direction. Next, the single cell 10 and the spacer 40 are bound by a binding mechanism. In one example, the single cells 10 and the spacers 40 are disposed between a pair of end plates 50A, 50B, and a plurality of straps 52 are bridged between the end plates 50A, 50B so as to apply a predetermined restraining load. As described above, the battery pack 1 can be manufactured.

Embodiment 2

Fig. 6 is a plan view of the nonaqueous electrolyte secondary battery 110 of embodiment 2. In fig. 6, the same members as those in embodiment 1 are denoted by the same reference numerals. The nonaqueous electrolyte secondary battery 110 includes a lid 134 instead of the lid 34. The nonaqueous electrolyte secondary battery 110 is the same as that of embodiment 1 except that a gas release mechanism is provided in the liquid injection stopper instead of the cap body. Therefore, the description of the portions common to embodiment 1 will be omitted or simplified.

As shown in fig. 6, the lid 134 includes a lid main body 134b, a positive electrode terminal 12T, a negative electrode terminal 14T, a liquid filling plug 138, and a valve portion (relief valve) 34 v. The positive electrode terminal 12T, the negative electrode terminal 14T, and the valve portion 34v may be the same as those of embodiment 1. Unlike embodiment 1, the cap main body 134b does not have a gas release mechanism. The lid main body 134b is provided with an annular liquid inlet 134h (see fig. 7). The pouring stopper 138 is attached to the pouring hole 134h, whereby the pouring hole 134h is hermetically sealed (sealed). The filling plug 138 is a substantially disk-shaped member. The liquid filling plug 138 is made of metal such as aluminum or stainless steel.

Fig. 7 is a sectional view of the liquid filling plug 138 as viewed in the thickness direction X. The gas release mechanism 138g is provided in the liquid filling cock 138. The gas release mechanism 138g includes a gas release portion 138n and a welding projection 138 p. However, the welding projection 138p is not essential and may be omitted. The filling plug 138 includes an outer edge portion s1, an inclined portion s2, and a central portion s 3.

The outer edge portion s1 extends along the outer surface (upper surface in fig. 7) of the cover main body 134 b. The outer edge portion s1 extends in a circular ring shape along the XY plane. The outer edge portion s1 is disposed at a position (upper side in fig. 7) farther from the housing main body 32 than the inclined portion s2 and the central portion s 3. The outer edge portion s1 has a welding projection 138p on its outer surface (upper surface in fig. 7). The shape, size, configuration, and the like of the welding projection 138p may be the same as those of the welding projection 34p of embodiment 1. The inclined portion s2 joins the outer edge portion s1 with the central portion s 3. The inclined portion s2 is connected from the end of the outer edge portion s1 on the side close to the center. The inclined portion s2 extends obliquely from the outer edge portion s1 toward the case main body 32 side (downward in fig. 7).

The central portion s3 is connected from the lower end of the inclined portion s 2. The central portion s3 extends parallel to the outer edge portion s 1. The central portion s3 expands in a circle along the XY plane of fig. 7. The gas release portion 138n is provided in the central portion s 3. The gas release portion 138n is constituted by a groove portion (notch) n 11. The shape, size, structure, and the like of the groove portion n11 may be the same as those of the groove portion n1 of embodiment 1. The inclined portion s2 and the central portion s3 constitute a stepped portion 138 s. The step portion 138s is recessed toward the case main body 32 side (downward in fig. 7) from the outer edge portion s 1. The step 138s protrudes toward the case main body 32 side (downward in fig. 7).

When the nonaqueous electrolyte secondary battery 110 having the above-described structure is collected from the market and reused in the battery pack 1, an operator applies an external force to the gas release portion 138n in the gas release step. Fig. 8A is a cross-sectional view of the gas release portion 138n in an open state as viewed from the thickness direction X. In the nonaqueous electrolyte secondary battery 110, the groove portion n11 is broken and the gas release portion 138n is opened. In the resealing step, the worker fits the sealing cap S along the inner edge of the welding protrusion 138p (see fig. 8B). Then, the worker welds the entire circumference of the seal cap S to the welding projection 138 p. Fig. 8B is a cross-sectional view of the gas release portion 138n in a state after resealing as viewed from the thickness direction X. In the nonaqueous electrolyte secondary battery 110, a welded joint portion W is formed over the entire circumference of the sealing cap S, and the gas release portion 138n is hermetically sealed.

Although the present invention has been described in detail, the above embodiments are merely examples, and the invention disclosed herein includes various modifications and changes to the specific examples described above.

For example, in embodiment 1, 1 gas release mechanism 34g is provided in the cap main body 34 b. In embodiment 2, 1 gas release mechanism 138g is provided in the liquid filling plug 138. However, the present invention is not limited thereto. The gas release mechanism may be provided in plural for 1 nonaqueous electrolyte secondary battery 10, 110. For example, the cover main body 34b of embodiment 1 may be provided with 2 or more gas release mechanisms 34 g. Alternatively, the lid main body 134b of embodiment 2 may be provided with the gas release mechanism 34 g. That is, as in the nonaqueous electrolyte secondary battery 210 shown in fig. 9, the gas release mechanism 34g may be provided in the lid main body 134b, and the gas release mechanism 138g may be provided in the liquid filling stopper 138. By providing the lid body with a plurality of gas release mechanisms, the nonaqueous electrolyte secondary battery after once reuse can be easily reused.