JP2007172880A - Battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery in which winding slippage of a cathode plate and an anode plate is prevented. <P>SOLUTION: The battery contains a power generating element 15 in which a cathode plate 20 and a anode plate 30 having mixture layers 22, 32 containing active material formed on current collectors 21, 31 are wound through a separator 16. The current collectors 21, 31 have a belt-shape surrounded by a pair of short sides and long sides, and is wound along the long-side direction so that one of the short-side side may be the center, and the mixture layers 22, 32 in the cathode plate 20 and the anode plate 30 have respectively thick portions 22B, 32B formed with the thickness thicker on one ends 21B, 31B side in width direction than the other ends 21A, 31A side in cross-section in parallel to the short side, and the cathode plate 20 and the anode plate 30 are arranged so that the thick portions 22B, 32B may be located mutually on opposite side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery and a manufacturing method thereof.

  For example, a non-aqueous electrolyte secondary battery is a battery container in which a power generation element composed of a positive electrode plate, a negative electrode plate, a non-aqueous electrolyte, and a separator is accommodated. Examples of the form of the power generation element include a stacked type and a wound type. Among these, in a battery having a relatively large capacity, a winding type battery in which positive and negative electrode plates connected to lead terminals are wound around the outer periphery of the core through a separator so as not to contact each other is preferable. Used for.

  In a winding type battery, an active material layer is formed on the positive and negative electrode plates by applying a mixture containing an active material on both surfaces of each current collector, and the lead terminals are superposed during the winding operation. It is attached to the portion of the positive and negative electrode plates where the composite material is not applied using means such as sonic welding. A wound body manufactured after finishing this winding operation is accommodated in a battery container, and after impregnating with a non-aqueous electrolyte, the container is sealed to manufacture a non-aqueous electrolytic secondary battery.

As a battery including such a winding type power generation element, a battery described in Patent Document 1 is known. A positive electrode mixture layer containing a positive electrode active material is uniformly applied to both surfaces of the positive electrode current collector to form a positive electrode mixture layer having a uniform thickness. A negative electrode mixture layer having a uniform thickness is formed by uniformly applying a negative electrode mixture containing an active material on both surfaces of the negative electrode current collector.
JP 2000-149953 A

  Since the positive electrode plate and the negative electrode plate of the battery described above are formed with a mixture layer having a uniform thickness on each surface, the lead terminal connection side is in a direction perpendicular to the winding direction during the winding operation. There is a possibility that a “winding deviation” that protrudes out of the battery container is generated, and the lead terminal that is housed in the battery container in this state and contacts the inner wall of the battery container may cause an internal short circuit.

  Further, even when the wound body that has finished the winding operation without causing a winding deviation is accommodated in the battery container, the positive electrode plate and the negative electrode plate are in the direction in which the lead terminals are connected, receiving vibration. Pulling causes a gap between the positive electrode plate and the negative electrode plate, resulting in a portion where the positive electrode mixture layer and the negative electrode mixture layer do not face each other, thereby increasing the internal resistance, and contact between the positive electrode plate and the negative electrode plate There was a problem that the risk of causing an internal short circuit increased.

  The present invention has been completed based on the above-described circumstances, and prevents winding deviation during the winding operation of the positive electrode plate and the negative electrode plate, and winding of the wound body after being accommodated in the battery container. An object is to provide a battery in which deviation is prevented.

  As a result of intensive studies to solve the above problems, the inventors of the present invention collected a mixture layer in which a portion (thick portion) whose thickness is thicker than that of the other end is formed on one end thereof. Winding is prevented by winding the positive electrode plate and the negative electrode plate on the electric conductor with the thick part of one mixture layer corresponding to the part of the other mixture layer opposite the thick part. And the knowledge that internal short circuit can be prevented was obtained.

  As a means for achieving the above object, the invention of claim 1 is characterized in that a positive electrode plate and a negative electrode plate each having a mixture layer containing an active material formed on a current collector are overlapped with a separator interposed therebetween. In a battery containing a rotating power generation element, the current collector has a band shape surrounded by a pair of short sides and long sides, and is wound along the long side direction so that one short side is centered. In the positive electrode plate and the negative electrode plate, the mixture layer has a thick portion with a thickness larger than that of the other end on one end side in the width direction in a cross section parallel to the winding axis. The battery is characterized in that the positive electrode plate and the negative electrode plate are formed so that the thick portions are located on opposite sides of each other.

  The invention according to claim 2 is the one according to claim 1, wherein in the positive electrode plate and the negative electrode plate, the mixture layer is one end side from the other end side in the width direction in a cross section parallel to the winding axis. By gradually increasing the thickness, the thick portion is formed at the edge portion on the long side of the positive electrode plate and the negative electrode plate.

  According to a third aspect of the present invention, in the one according to the first or second aspect, at least one of the mixture layer of the positive electrode plate and the mixture layer of the negative electrode plate is in a cross section parallel to the winding axis. It is characterized in that the thickness difference between the thick part and the thin part with the smallest thickness is 5 to 20 μm.

  According to the invention of claim 4, a positive electrode plate and a negative electrode plate in which a mixture layer containing an active material is formed on a current collector having a band shape surrounded by a pair of short sides and long sides are sandwiched between separators. In the method of manufacturing a battery containing a power generating element wound along the long side direction so that one short side of the current collector is the center, the current collector of the positive electrode plate and the negative electrode plate After applying the mixture containing the active material to the cross section, by applying pressure, in the cross section parallel to the winding axis, one end side in the width direction is thicker than the other end side It is a manufacturing method of the battery characterized by including the press process in which a part is formed.

<Invention of Claim 1>
According to the invention described in claim 1, in the positive electrode plate and the negative electrode plate, the mixture layer is thicker at one end side in the width direction than at the other end side in a cross section parallel to the winding axis. A thick part is formed, and the positive electrode plate and the negative electrode plate are arranged so that the thick part is located on the opposite side. Therefore, since the mixture layer of the positive electrode plate and the mixture layer of the negative electrode plate are positioned relative to each other at the time of winding, even if a force is applied in the direction in which the lead terminals are connected during the winding operation, the winding is not displaced. It is hard to happen.

Moreover, since the positive electrode plate and the negative electrode plate are positioned and wound, and the end faces of the wound body after winding are aligned, the positive electrode plate and the negative electrode plate are subjected to vibration after being accommodated in the battery container, and the lead terminals Even if pulled in the direction in which is connected, it is difficult for a displacement to occur between the positive electrode plate and the negative electrode plate.
Therefore, according to the present invention, it is possible to provide a battery that prevents the winding displacement during winding operation of the positive electrode plate and the negative electrode plate and prevents the winding body from being unwound after being accommodated in the battery container. Can do.

<Invention of Claim 2>
According to the invention described in claim 2, in the positive electrode plate and the negative electrode plate, the mixture layer is gradually increased in thickness from the other end side in the width direction to the one end side in a cross section parallel to the winding axis. Since the thick part is formed at the edge of the long side of the positive electrode plate and the negative electrode plate, even if the positive electrode plate and the negative electrode plate are misaligned due to vibration or the like, the mixture of the positive electrode plate The gap between the layer and the mixture layer of the negative electrode plate is not greatly opened. Therefore, even in such a case, an internal short circuit does not occur.

<Invention of Claim 3>
According to the invention described in claim 3, at least one of the mixture layer of the positive electrode plate and the mixture layer of the negative electrode plate has a thickness difference of 5 to 20 μm between the thick part and the thinnest part formed most thinly. Therefore, winding slippage can be prevented more suitably.

<Invention of Claim 4>
According to invention of Claim 4, after apply | coating the mixture containing an active material to the collector of a positive electrode plate and a negative electrode plate, the width direction is applied in the cross section parallel to a winding axis | shaft by applying a pressure. Since the one end side is provided with a pressing step in which a thick portion having a thickness larger than that of the other end side is formed, the battery of the present invention can be easily manufactured.

<Embodiment 1>
Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
FIG. 1 shows a nonaqueous electrolyte secondary battery 10 (hereinafter referred to as a battery 10) in a completed form in a broken state. The battery 10 includes a battery container 11 formed in a cylindrical shape, and a power generation element 15 accommodated therein.

  The battery container 11 includes a metal battery container 11 formed in the shape of a cylindrical container with a bottom, and a metal cap 12 formed in a substantially disk shape and sealing the opening of the battery container 11. ing. A power generation element 15 configured in a spiral shape is accommodated in the battery container 11 with disk-shaped insulating plates 13 disposed above and below the power generation element 15. A cap 12 is caulked to the opening of the battery container 11 via a sealing gasket 14. In addition, a non-aqueous electrolyte is injected into the battery container 11.

  The non-aqueous electrolyte solution is obtained by dissolving an electrolyte salt in a non-aqueous solvent. Use polar solvents such as formamide, dimethylacetamide, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, methyl acetate, vinylene carbonate alone or in admixture of two or more. be able to.

The electrolyte salts that dissolve in the non-aqueous solvent are LiPF ₆ , LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiCF ₃ CO ₂ , LiCF ₃ (CF ₃ ) ₃ , LiCF ₃ (C ₂ F ₅ ) ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ CF ₂ CF ₃ ) ₂ , LiN (COCF ₃ ) ₂ , LiN (COCF ₂ CF ₃ ) ₂ , LiPF ₃ (CF ₂ CF ₃ ) _{3 and the} like alone Or a mixture of two or more.

The power generation element 15 accommodated in the battery container 11 is configured by winding a positive electrode plate 20 and a negative electrode plate 30 with a separator 16 interposed therebetween.
As the separator 16, a woven fabric, a nonwoven fabric, a synthetic resin microporous membrane, or the like can be used, and a synthetic resin microporous membrane can be particularly preferably used. Among these, polyolefin microporous membranes such as polyethylene and polypropylene microporous membranes, or microporous membranes composed of these can be suitably used in terms of thickness, membrane strength, membrane resistance, and the like.

  The positive electrode plate 20 has a positive electrode mixture layer 22 (described later) containing a positive electrode active material capable of occluding and releasing lithium ions on both surfaces of a positive electrode current collector 21 having a thickness of 10 to 20 μm formed of a metal such as aluminum. It has. As shown in FIG. 3, the positive electrode current collector 21 has a band shape, specifically, a shape surrounded by a pair of short sides 25A and 25B of 10 to 20 cm and long sides 26A and 26B of 1 to 5 m. There is no. The predetermined belt-like region including the long side 26 </ b> A is a mixture layer non-formed part 24 in which the positive electrode mixture layer 22 is not formed. A large number of positive electrode lead terminals 23 are connected to the mixture layer non-formed part 24 at intervals of about 10 cm so as to intersect the long side 26A. The positive electrode lead terminals 23 are gathered together after being wound, and their tip portions protrude upward from the positive electrode plate 20 and are connected to the cap 12 serving as a positive electrode terminal. As a material of the positive electrode lead terminal 23, a metal such as aluminum, nickel, or titanium can be used.

The transition metal oxide that occludes and releases lithium used as the positive electrode active material has a composition formula of Li _x MO ₂ , Li _y M ₂ O ₄ , and Na _x MO ₂ (where M is one or more transition metals, 0 ≦ x A composite oxide represented by ≦ 1, 0 ≦ y ≦ 2), a metal chalcogenide having a tunnel structure or a layered structure, or a metal oxide can be used. Specific examples thereof include LiCoO ₂ , LiNiO ₂ , LiNi _1/2 Mn _1/2 O ₂ , LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiCo _x Ni _1-x O ₂ , LiMn ₂ O. ₄ , Li ₂ Mn ₂ O ₄ , MnO ₂ , FeO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ or TiS ₂ .

  In addition to the above-described positive electrode active material, a conductive agent, a binder, and the like can be added to the composition containing the positive electrode active material that forms the positive electrode mixture layer 22 (hereinafter referred to as the positive electrode mixture composition). As the conductive agent, an inorganic compound or an organic compound can be used. As the inorganic compound, carbon black, graphite and the like can be used, and as the organic compound, for example, a conductive polymer such as polyaniline can be used. As the binder, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, styrene-butadiene rubber, polyacrylonitrile and the like can be used alone or in combination.

  The negative electrode plate 30 includes a negative electrode mixture layer 32 including a negative electrode active material capable of occluding and releasing lithium ions on both surfaces of a negative electrode current collector 31 formed of a copper foil having a thickness of 10 to 20 μm formed of a metal such as copper. (To be described later). The negative electrode current collector 31 has a strip shape, specifically, a shape surrounded by a pair of short sides 35A and 35B of 10 to 20 cm and long sides 36A and 36B of 1 to 5 m. The predetermined belt-like region including the long side 36 </ b> A is a mixture layer non-formed part 34 in which the negative electrode mixture layer 32 is not formed. A large number of negative electrode lead terminals 33 are connected to the mixture layer non-formed part 34 at intervals of about 10 cm so as to intersect the long side 36A. The negative electrode lead terminals 33 are gathered together after being wound, and their tip portions protrude downward from the negative electrode plate 30 and are connected to the bottom portion of the battery container 11 which functions as a negative electrode terminal. As a material of the negative electrode lead terminal 33, a metal such as copper or nickel can be used, and a copper foil plated with nickel is preferable.

Examples of the negative electrode active material include alloys of lithium such as Al, Si, Pb, Sn, Zn, and Cd, metal oxides such as LiFe ₂ O ₃ , WO ₂ , MoO ₂ , SiO, and CuO, carbon such as graphite and carbon. A material, lithium nitride such as Li ₅ (Li ₃ N), metallic lithium, or a mixture thereof can be used.

  Now, as shown in FIG. 2, the positive electrode mixture layer 22 has one end 21 </ b> B from the other end 21 </ b> A side adjacent to the unmixed portion 24 on the positive electrode current collector 21 (the edge portion on the long side in the present invention). It is formed so that the thickness gradually increases toward the side. The average thickness of one side of the positive electrode mixture layer 22 is around 100 μm, and the thickest portion 22B formed on the one end 21B side of the positive electrode mixture layer 22 and the thin wall formed on the other end side 21A are thinnest. The difference in thickness from the portion 22A is preferably 5 to 20 μm (the invention according to claim 3). If the difference in thickness is less than 5 μm, lateral displacement may occur during winding, and if it exceeds 20 μm, the winding operation is difficult when the separator 16 is attached to the negative electrode plate 30 as a counterpart.

  The thickness of the negative electrode mixture layer 32 gradually increases from the other end 31A side to which the negative electrode lead terminal 33 on the negative electrode current collector 31 is connected to the one end 31B (corresponding to the end portion on the long side in the present invention). It is formed to increase the thickness. The average thickness of one side of the negative electrode mixture layer 32 is around 100 μm, and among the negative electrode mixture layer 32, the thickest part 32B formed on the one end 31B side and the thinnest wall formed on the other end 31A side are formed thinnest. The difference in thickness from the portion 32A is preferably 5 to 20 μm (the invention according to claim 2). If the difference in thickness is less than 5 μm, lateral displacement may occur during winding, and if it exceeds 20 μm, the winding operation tends to be difficult when mating the positive electrode plate 20 with the separator 16 in between.

Next, a method for manufacturing the battery 10 of this embodiment will be described.
First, the mixture layers 22 and 32 are formed by applying a mixture composition containing each active material on both surfaces of each of the current collectors 21 and 31, drying and rolling with a roll press. The positive electrode plate 20 and the negative electrode plate 30 are manufactured.

Specifically, by changing the coating amount of the mixture composition, the current increases on the current collectors 21 and 31 of the positive electrode plate 20 and the negative electrode plate 30 from the other end 21A, 31A side toward the one end 21B, 31B side. A method of applying pressure so that the thickness of the agent layers 22 and 32 is increased, and when applying a mixture composition, a substantially equal amount of the mixture composition is applied and then pressure is applied. Further, there is a method (invention of claim 4) through a pressing process in which the mixture layers 22 and 32 are formed thicker as they approach from the other end 21A, 31A side to the one end 21B, 31B side.
Among these, since the electrode plates 20 and 30 of the battery 10 of the present invention can be easily obtained, the production method through the pressing step is preferable.

  When applying the mixture composition, a general application method such as a reverse roll method, a direct roll method, a blade method, a knife method, or a dip method can be used, but the application amount can be easily controlled mechanically. Therefore, it is preferable to carry out by a die nozzle method.

  When pressure is applied to the mixture layer, roll pressing may be performed by changing the left and right forces of the roll, or roll pressing may be performed by changing the distance between the rolls.

  Next, the thin portion 32A of the negative electrode mixture layer 32 of the negative electrode plate 30 is arranged on the thick portion 22B of the positive electrode mixture layer 22 of the positive electrode plate 20 obtained by the above method, and the positive electrode plate 20 and the negative electrode plate 30 are combined. A power generation element 15 is manufactured through a winding process in which the separator 16 is wound. The lead terminals 23 and 33 connected to the positive electrode plate 20 and the negative electrode plate 30 are attached to the unmixed portions 24 and 34 of the positive and negative electrode plates 20 and 30 using means such as ultrasonic welding during the winding process. .

  Next, the power generation element 15 manufactured after finishing the winding process is accommodated in the battery container 11, and after impregnating the non-aqueous electrolyte, the container is sealed to manufacture the battery 10 of the present embodiment.

  According to the present embodiment, the thin portion 32 </ b> A of the negative electrode mixture layer 32 of the negative electrode plate 30 is arranged on the thick portion 22 </ b> B of the positive electrode mixture layer 22 of the positive electrode plate 20. Is wound with the separator 16 in between, the positive electrode plate 20 and the negative electrode plate 30 are positioned relative to each other during winding, and even if a force is applied in the direction in which the lead terminals 23 and 33 are connected during the winding operation. It is hard to produce a gap Further, since the end surfaces of the wound bodies are aligned, even if the positive electrode plate 20 and the negative electrode plate 30 are pulled in the direction in which the lead terminals 22 and 32 are connected by vibration after being accommodated in the battery container 11, the positive electrode A shift is unlikely to occur between the plate 20 and the negative electrode plate 30. Even if a deviation occurs, the gap between the mixture layer 22 of the positive electrode plate 20 and the mixture layer 32 of the negative electrode plate 30 does not open greatly, and even in such a case, an internal short circuit occurs. There is no. As a result, according to the present embodiment, it is possible to provide the battery 10 that prevents winding deviation and prevents an internal short circuit that may be caused by vibration after winding.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

  (1) In Embodiment 1, the thickness of the positive electrode mixture layer and the negative electrode mixture layer is gradually increased from the other end side adjacent to the unmixed portion on the current collector to the one end side. Although formed, it is not limited to this shape, The thick part which thickened the thickness from the other end side should just be formed in the one end side.

  (2) In the present invention, not only the nonaqueous electrolytic solution but also a solid electrolyte may be used, or both may be used in combination. As the solid electrolyte, a known solid electrolyte can be used. For example, an inorganic solid electrolyte or a polymer solid electrolyte can be used. When a gel polymer solid electrolyte is used, the electrolyte constituting the gel may be different from the electrolyte contained in the pores of the active material of the electrode plate. A synthetic resin microporous membrane and a polymer solid electrolyte can also be used in combination.

  (3) Although a cylindrical battery container is used in Embodiment 1, the battery container may be oval or bag-shaped, and the material may be a metal laminate resin film.

  (4) The size of the current collector, the connection position of the lead terminal, and the like are not limited to those described in the first embodiment. For example, the mixture layer non-formed portion is formed in a predetermined region parallel to the short side of the current collector. The lead terminal may be provided so as to cross the short side.

Overall view of the battery of Embodiment 1 Sectional view parallel to the short sides of the positive and negative plates Front view of positive and negative plates

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Battery 20 ... Positive electrode plate 21 ... Positive electrode collector 21A ... Other end 21B ... One end 22 ... Positive electrode mixture layer 22B ... Thick part 23 ... Positive electrode lead terminal 24 ... Mixture layer non-formation part 30 ... Negative electrode plate 31 ... Negative electrode current collector 31A ... the other end 31B ... one end 32 ... negative electrode mixture layer 32B ... thick part 33 ... negative electrode lead terminal 34 ... mixture layer unformed part

Claims (4)

In a battery containing a power generation element formed by stacking and winding a positive electrode plate and a negative electrode plate on which a mixture layer containing an active material is formed on a current collector with a separator interposed therebetween,
The current collector has a belt shape surrounded by a pair of short sides and long sides, and is wound along the long side direction so that one short side is the center,
In the positive electrode plate and the negative electrode plate, the mixture layer is formed with a thick portion having a thickness larger than that of the other end side on one end side in the width direction in a cross section parallel to the winding axis. And the positive electrode plate and the negative electrode plate are arranged so that the thick portions are positioned on opposite sides of each other. In the positive electrode plate and the negative electrode plate, both of the mixture layers gradually increase in thickness from the other end side to the one end side in the width direction in a cross section parallel to the winding axis, so that the thick portion becomes the positive electrode The battery according to claim 1, wherein the battery is formed at an edge portion on a long side of the plate and the negative electrode plate. At least one of the mixture layer of the positive electrode plate and the mixture layer of the negative electrode plate has a thickness difference of 5 to 5 between the thick portion and the thinned portion having the smallest thickness in a cross section parallel to the winding axis. The battery according to claim 1, wherein the battery is formed to have a thickness of 20 μm. A positive electrode plate and a negative electrode plate in which a mixture layer containing an active material is formed on a current collector having a band shape surrounded by a pair of short sides and a long side, with a separator interposed therebetween, one of the current collectors In the manufacturing method of the battery containing the power generation element wound along the long side direction so that the short side of the
After applying a mixture containing the active material to the current collectors of the positive electrode plate and the negative electrode plate, pressure is applied to the other end of the cross section parallel to the winding axis on one end side in the width direction. A method for manufacturing a battery, comprising a pressing step in which a thick portion having a thickness larger than that of an end side is formed.

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