JP5439317B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery.

In a cylindrical or prismatic secondary battery typified by a lithium secondary battery, an electrode group is formed by winding a sheet-like positive electrode and a negative electrode from the inner periphery to the outer periphery via a separator. A current collecting member is attached to the electrode group and accommodated in a battery can. An electrolytic solution is injected into the battery can, and the battery can and the lid member are sealed from the outside.
In a cylindrical secondary battery, a gasket is interposed between the battery can and the lid member, and sealing is performed by caulking. In the positive electrode, a positive electrode mixture is formed on both surfaces of the metal plate so that a positive electrode exposed portion is formed along one side surface. A number of positive electrode leads are formed on the positive electrode exposed portion, and the tip of each positive electrode lead is welded to the positive electrode current collecting member. In the negative electrode, a negative electrode mixture is formed on both surfaces of the metal plate so that a negative electrode exposed portion is formed along the other side surface on the side facing the one side edge of the positive electrode. A number of negative electrode leads are formed on the negative electrode exposed portion, and the tip of each negative electrode lead is welded to the negative electrode current collector.

  In the above structure, the positive electrode lead may come into contact with the gasket due to vibration or impact, and the positive electrode lead may be cut. When the positive electrode lead is cut, the internal resistance of the battery increases and the current discharge performance decreases. For this reason, a lithium secondary battery having a structure in which an insulator is formed on the positive electrode lead to prevent direct contact between the gasket and the positive electrode lead is known (for example, see Patent Document 1).

JP 2009-295389 A

In the secondary battery, an internal short circuit occurs even after the electrode group is accommodated in the battery container and the electrolytic solution is injected into the battery container. Although the details of this phenomenon will be described later, the main point is that ions are generated from the positive electrode side due to the foreign matter mixed in the electrolyte solution, penetrate the separator and grow on the negative electrode, that is, deposit on the negative electrode. This is due to the phenomenon of accumulation. As a result, the deposit generated on the negative electrode causes an internal short circuit between the positive electrode and the negative electrode, which decreases the reliability of the secondary battery.
In the invention described in the above-described prior art, since the insulator has a structure that covers only the positive electrode lead, it is deposited due to the foreign material entering from between the separator and the positive electrode or the foreign material generated on the negative electrode side. It is impossible to prevent an internal short circuit from occurring due to the deposit.

  The secondary battery of the present invention includes a sheet-like positive electrode having a positive electrode exposed portion formed along one side edge and a sheet-like negative electrode having a negative electrode exposed portion formed along the other side edge. An electrode group wound from the inner periphery to the outer periphery via a sheet-like separator, a positive electrode current collecting member to which the positive electrode exposed portion of the positive electrode is bonded, and a negative electrode current collector to which the negative electrode exposed portion of the negative electrode is bonded An electric member, an electrode group, a positive electrode current collecting member, a negative electrode current collecting member, a battery can into which an electrolyte is injected, and a positive electrode exposed portion exposed from one side surface of the electrode group or the other side surface of the electrode group And an insulating material that covers at least one predetermined region of the negative electrode exposed portion exposed from the inner surface, and the insulating material includes the positive electrode exposed portion or the negative electrode exposed portion from the innermost periphery to the outermost periphery, and the positive electrode exposed portion or the negative electrode exposed portion. Cover the end of the separator adjacent to the outer periphery And wherein the Rukoto.

  The insulating material covers the edge of the outermost positive electrode exposed part or the outer periphery of the negative electrode exposed part together with the positive electrode exposed part or the negative electrode exposed part exposed from the side surface of the electrode group. Alternatively, it is possible to prevent an internal short circuit from occurring due to deposits deposited due to the foreign matter generated on the negative electrode side.

Sectional drawing of the cylindrical secondary battery as Embodiment 1 of the secondary battery which concerns on this invention. FIG. 2 is an exploded perspective view of the cylindrical secondary battery illustrated in FIG. 1. The perspective view of the state which cut | disconnected a part for showing the detail of the electrode group illustrated by FIG. The expanded sectional view by the side of the lid of the cylindrical secondary battery illustrated in FIG. FIG. 2 is an enlarged cross-sectional view of a can bottom side of the cylindrical secondary battery illustrated in FIG. 1. FIG. 2 is an enlarged cross-sectional view of the vicinity of an insulating material provided on the positive electrode side in the cylindrical secondary battery illustrated in FIG. 1. FIG. 2 is an enlarged cross-sectional view of the vicinity of an insulating material provided on the negative electrode side in the cylindrical secondary battery illustrated in FIG. 1. Sectional drawing by the side of a cover body which shows the modification 1 of the covering structure by an insulating material. Sectional drawing of the can bottom side which shows the modification 2 of the coating | coated structure by an insulating material. Sectional drawing of the can bottom side which shows the modification 3 of the coating | coated structure by an insulating material. Sectional drawing of the can bottom side which shows the modification 4 of the covering structure by an insulating material. FIG. 2 is a process flow diagram illustrating an example of a method for manufacturing the cylindrical secondary battery illustrated in FIG. 1. Sectional drawing which shows Embodiment 2 of the secondary battery which concerns on this invention. The top view of the electrode group of the state which removed the cover unit in FIG. Sectional drawing by the side of the cover body which shows Embodiment 3 of the secondary battery which concerns on this invention. The perspective view of the electric power generation unit in FIG. 15, and an insulating material.

--Embodiment 1--
(Overall structure of secondary battery)
Hereinafter, the secondary battery of the present invention will be described with reference to the drawings, taking a lithium ion cylindrical secondary battery as an embodiment.
FIG. 1 is a cross-sectional view of the cylindrical secondary battery 1, and FIG. 2 is an exploded perspective view of the cylindrical secondary battery 1 shown in FIG. However, the battery can 2 is not shown in FIG.
The cylindrical secondary battery 1 has dimensions of, for example, an outer diameter of 40 mmφ and a height of 100 mm.
In the cylindrical secondary battery 1, a bottomed cylindrical battery can 2 and a hat-shaped lid 3 are usually crimped through a seal member 43 called a gasket and sealed from the outside. It has the battery container 4 of a structure. The bottomed cylindrical battery can 2 is formed by pressing a metal plate such as iron, aluminum or stainless steel, and a plating film such as nickel is formed on the entire outer and inner surfaces. A groove 2 a protruding to the inside of the battery can 2 is formed on the opening side above the battery can 2. Inside the battery can 2, each component for power generation described below is accommodated.

Reference numeral 10 denotes an electrode group having a shaft core 15 at the center, and a positive electrode and a negative electrode wound around the shaft core 15. FIG. 3 is a perspective view showing the details of the structure of the electrode group 10, with a part thereof cut. As shown in FIG. 3, the electrode group 10 has a configuration in which a positive electrode 11, a negative electrode 12, and first and second separators 13 and 14 are wound around an axis 15.
The shaft core 15 has a hollow cylindrical shape. On the shaft core 15, a negative electrode 12, a first separator 13, a positive electrode 11, and a second separator 14 are laminated and wound in this order. Inside the innermost negative electrode 12, the first separator 13 and the second separator 14 are wound several times (one turn in FIG. 3). The outermost periphery is the negative electrode 12 and the first separator 13 wound around the outer periphery. The first separator 13 on the outermost periphery is fastened with an adhesive tape 19 (see FIG. 2).

  The positive electrode 11 is formed of an aluminum foil and has a long shape. The positive electrode 11 includes a positive electrode sheet 11a and a positive electrode processing portion in which a positive electrode mixture 11b is applied to both surfaces of the positive electrode sheet 11a. One side edge on the upper side along the longitudinal direction of the positive electrode sheet 11a is a positive electrode mixture untreated portion (positive electrode exposed portion) 11c where the positive electrode mixture 11b is not applied and an aluminum foil is exposed. In the positive electrode mixture untreated portion 11 c, a large number of positive electrode leads 16 protruding upward in parallel with the shaft core 15 are integrally formed at equal intervals.

  The positive electrode mixture 11b includes a positive electrode active material, a positive electrode conductive material, and a positive electrode binder. The positive electrode active material is preferably lithium oxide. Examples include lithium cobaltate, lithium manganate, lithium nickelate, lithium composite oxide (lithium oxide containing two or more selected from cobalt, nickel, and manganese). The positive electrode conductive material is not limited as long as it can assist transmission of electrons generated by the occlusion / release reaction of lithium in the positive electrode mixture to the positive electrode. However, good characteristics can be obtained by using a lithium composite oxide composed of lithium cobaltate, lithium manganate, and lithium nickelate, which is the above-mentioned material.

  The positive electrode binder can bind the positive electrode active material and the positive electrode conductive material, and can bind the positive electrode mixture and the positive electrode current collector, and should not deteriorate significantly due to contact with the non-aqueous electrolyte. There is no particular limitation. Examples of the positive electrode binder include polyvinylidene fluoride (PVDF) and fluororubber. The method for forming the positive electrode mixture is not limited as long as the positive electrode mixture is formed on the positive electrode. As an example of a method of forming the positive electrode mixture 11b, a method of applying a dispersion solution of constituent materials of the positive electrode mixture 11b on the positive electrode sheet 11a can be given. By producing by such a method, a positive electrode mixture having excellent characteristics can be obtained.

  Examples of a method for applying the positive electrode mixture 11b to the positive electrode sheet 11a include a roll coating method and a slit die coating method. N-methylpyrrolidone (NMP), water, etc. are added to the positive electrode mixture 11b as an example of a solvent for the dispersion solution, and the kneaded slurry is uniformly applied to both surfaces of an aluminum foil having a thickness of 20 μm, dried, and then cut. To do. An example of the coating thickness of the positive electrode mixture 11b is about 40 μm on one side. When cutting the positive electrode sheet 11a, the positive electrode lead 16 is integrally formed. All the positive leads 16 have substantially the same length.

  The negative electrode 12 is formed of a copper foil and has a long shape. The negative electrode 12 includes a negative electrode sheet 12a and a negative electrode processing portion in which a negative electrode mixture 12b is applied to both surfaces of the negative electrode sheet 12a. The lower side edge along the longitudinal direction of the negative electrode sheet 12a is a negative electrode mixture untreated portion (negative electrode exposed portion) 12c where the negative electrode mixture 12b is not applied and the copper foil is exposed. In the negative electrode mixture untreated portion 12c, a large number of negative electrode leads 17 extending in the direction opposite to the positive electrode lead 16 are integrally formed at equal intervals. With this structure, the current can be distributed in a substantially uniform manner, leading to an improvement in the reliability of the lithium ion secondary battery.

  The negative electrode mixture 12b includes a negative electrode active material, a negative electrode binder, and a thickener. The negative electrode mixture 12b may have a negative electrode conductive material such as acetylene black. As the negative electrode active material, it is preferable to use graphitic carbon, particularly artificial graphite. However, among them, a negative electrode mixture having excellent characteristics can be obtained by the method described below. By using graphite carbon, a lithium ion secondary battery for a plug-in hybrid vehicle or an electric vehicle requiring a large capacity can be manufactured. The formation method of the negative electrode mixture 12b is not limited as long as the negative electrode mixture 12b is formed on the negative electrode sheet 12a. As an example of a method of applying the negative electrode mixture 12b to the negative electrode sheet 12a, a method of applying a dispersion solution of constituent materials of the negative electrode mixture 12b onto the negative electrode sheet 12a can be mentioned. Examples of the coating method include a roll coating method and a slit die coating method.

  As an example of a method of applying the negative electrode mixture 12b to the negative electrode sheet 12a, N-methyl-2-pyrrolidone or water as a dispersion solvent is added to the negative electrode mixture 12b, and the kneaded slurry is made of a rolled copper foil having a thickness of 10 μm. Apply uniformly on both sides, dry, and then cut. An example of the coating thickness of the negative electrode mixture 12b is about 40 μm on one side. When the negative electrode sheet 12a is cut, the negative electrode lead 17 is integrally formed. All the negative leads 17 have substantially the same length.

The width WS of the first separator 13 and the second separator 14 is formed larger than the width WC of the negative electrode mixture 12b formed on the negative electrode sheet 12a. Further, the width WC of the negative electrode mixture 12b formed on the negative electrode sheet 12a is formed larger than the width WA of the positive electrode mixture 11b formed on the positive electrode sheet 11a.
Since the width WC of the negative electrode mixture 12b is larger than the width WA of the positive electrode mixture 11b, an internal short circuit due to the precipitation of foreign matters is prevented. This is because in the case of a lithium ion secondary battery, lithium as the positive electrode active material is ionized and penetrates the separator, but the negative electrode sheet is not formed on the negative electrode side and the negative electrode sheet 12a is exposed. This is because lithium is deposited on 12a and causes an internal short circuit.

The first and second separators 13 and 14 are, for example, polyethylene porous films having a thickness of 40 μm.
1 and 3, the hollow cylindrical shaft core 15 is formed with a large-diameter groove 15a on the inner surface of the upper end in the axial direction (vertical direction in the drawing), and the positive electrode current collecting member 27 is press-fitted into the groove 15a. Has been.

  The positive electrode current collecting member 27 is made of, for example, aluminum, and has a disk-shaped base portion 27a, a lower cylindrical portion 27b that protrudes toward the shaft core 15 at the inner peripheral portion of the base portion 27a and is press-fitted into the inner surface of the shaft core 15. And an upper cylindrical portion 27c that protrudes toward the lid 3 at the outer peripheral edge. An opening 27d for discharging gas generated inside the battery is formed in the base 27a of the positive electrode current collecting member 27. Moreover, although the opening part 27e is formed in the positive electrode current collection member 27, the function of the opening part 27e is mentioned later.

  All of the positive leads 16 of the positive electrode sheet 11 a are welded to the upper cylindrical portion 27 c of the positive current collecting member 27. In this case, as shown in FIG. 2, the positive electrode lead 16 is overlapped and bonded onto the upper cylindrical portion 27 c of the positive electrode current collecting member 27. Since each positive electrode lead 16 is very thin, a large current cannot be taken out by one. Therefore, a large number of positive leads 16 are formed at predetermined intervals over the entire length from the start to the end of winding around the shaft core 15.

Since the positive electrode current collecting member 27 is oxidized by the electrolytic solution, the reliability can be improved by forming it with aluminum. As soon as the surface of aluminum is exposed by some processing, an aluminum oxide film is formed on the surface, and this aluminum oxide film can prevent oxidation by the electrolytic solution.
Further, by forming the positive electrode current collecting member 27 with aluminum, the positive electrode lead 16 of the positive electrode sheet 11a can be welded by ultrasonic welding or spot welding.

  The positive electrode lead 16 and the ring-shaped pressing member 28 of the positive electrode sheet 11a are welded to the outer periphery of the upper cylindrical portion 27c of the positive electrode current collecting member 27. A number of positive leads 16 are brought into close contact with the outer periphery of the upper cylindrical portion 27 c of the positive current collecting member 27, and a pressing member 28 is wound around the outer periphery of the positive lead 16 to be temporarily fixed, and are welded in this state.

On the outer periphery of the lower end portion of the shaft core 15, a step portion 15b having a small outer diameter is formed, and the negative electrode current collector 21 is press-fitted and fixed to the step portion 15b. The negative electrode current collecting member 21 is made of, for example, copper, and an opening 21b that is press-fitted into the step portion 15b of the shaft core 15 is formed in a disk-shaped base portion 21a. An outer peripheral cylindrical portion 21c that protrudes out is formed.
All of the negative electrode leads 17 of the negative electrode sheet 12a are welded to the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21 by ultrasonic welding or the like. Since each negative electrode lead 17 is very thin, a large number of negative leads 17 are formed at predetermined intervals over the entire length from the start of winding to the shaft core 15 to take out a large current.

The negative electrode lead 17 of the negative electrode sheet 12a and the ring-shaped pressing member 22 are welded to the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21. A number of the negative electrode leads 17 are brought into close contact with the outer periphery of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21, and the holding member 22 is wound around the outer periphery of the negative electrode lead 17 to be temporarily fixed, and are welded in this state.
A negative electrode conducting lead 23 made of copper is welded to the lower surface of the negative electrode current collecting member 21.
The negative electrode conducting lead 23 is welded to the battery can 2 at the bottom of the battery can 2. The battery can 2 can be formed by, for example, forming carbon steel having a thickness of 0.5 mm and applying a nickel plating film on the surface. By using such a material, the negative electrode conducting lead 23 can be welded to the battery can 2 by resistance welding or the like.

  Here, the opening 27 e formed in the positive current collecting member 27 is for inserting an electrode rod (not shown) for welding the negative electrode conducting lead 23 to the battery can 2. More specifically, the electrode rod is inserted into the hollow portion of the shaft core 15 through the opening 27e formed in the positive electrode current collecting member 27, and the negative electrode energizing lead 23 is pressed against the inner surface of the bottom of the battery can 2 at the tip portion. I do. The battery can 2 connected to the negative electrode current collecting member 21 acts as one output end, and the electric power stored in the electrode group 10 can be taken out from the battery can 2.

  A large number of positive electrode leads 16 are welded to the positive electrode current collector member 27, and a large number of negative electrode leads 17 are welded to the negative electrode current collector member 21, whereby the positive electrode current collector member 27, the negative electrode current collector member 21 and the electrode group 10 are integrated. A unitized power generation unit 20 is configured (see FIG. 2). However, in FIG. 2, for the convenience of illustration, the negative electrode current collecting member 21, the pressing member 22, and the negative electrode energizing lead 23 are illustrated separately from the power generation unit 20.

  A flexible connection member 33 formed by laminating a plurality of aluminum foils is joined to the upper surface of the base portion 27a of the positive electrode current collecting member 27 by welding one end thereof. The connection member 33 can flow a large current by laminating and integrating a plurality of aluminum foils, and is provided with flexibility. In other words, it is necessary to increase the thickness of the connecting member in order to pass a large current, but if it is formed of a single metal plate, the rigidity increases and the flexibility is impaired. Therefore, a large number of aluminum foils having a small thickness are laminated to give flexibility. The connecting member 33 has a thickness of, for example, about 0.5 mm, and is formed by stacking five aluminum foils having a thickness of 0.1 mm.

A ring-shaped insulating plate 34 made of an insulating resin material having a circular opening 34 a is placed on the upper cylindrical portion 27 c of the positive electrode current collecting member 27.
The insulating plate 34 has an opening 34a (see FIG. 2) and a side portion 34b protruding downward. A connection plate 35 is fitted in the opening 34 a of the insulating material 34. The other end of the flexible connection member 33 is welded and fixed to the lower surface of the connection plate 35.

  The connection plate 35 is formed of an aluminum alloy, and has a substantially dish shape that is substantially uniform except for the central portion and is bent to a slightly lower position on the central side. The thickness of the connection plate 35 is, for example, about 1 mm. At the center of the connecting plate 35, a thin dome-shaped projection 35a is formed, and a plurality of openings 35b (see FIG. 2) are formed around the projection 35a. The opening 35b has a function of releasing gas generated inside the battery.

  The protrusion 35 a of the connection plate 35 is joined to the bottom surface of the center portion of the diaphragm 37 by resistance welding or friction diffusion bonding. The diaphragm 37 is formed of an aluminum alloy, and has a circular cut 37 a centering on the center of the diaphragm 37. The cut 37a is formed by crushing the upper surface side into a V shape by pressing and thinning the remainder.

  The diaphragm 37 is provided for ensuring the safety of the battery. When the internal pressure of the battery rises, as a first stage, the diaphragm 37 warps upward, peels off the joint with the protruding portion 35a of the connection plate 35, and connects the connection plate 35. The connection with the connection plate 35 is cut off. As a second stage, when the internal pressure still rises, it has a function of cleaving at the cut 37a and releasing the internal gas.

The diaphragm 37 fixes the peripheral portion 3a of the lid 3 at the peripheral portion. As shown in FIG. 2, the diaphragm 37 initially has a side portion 37 b erected vertically toward the lid 3 at the peripheral portion. The lid body 3 is accommodated in the side portion 37b, and the side portion 37b is bent and fixed to the upper surface side of the lid body 3 by caulking.
The lid 3 is made of iron such as carbon steel, and a plating film such as nickel is applied to the entire outer and inner surfaces. The lid 3 has a hat shape having a disc-shaped peripheral edge 3a that contacts the diaphragm 37 and a headless bottomless cylindrical portion 3b that protrudes upward from the peripheral edge 3a. An opening 3c is formed in the cylindrical portion 3b. The opening 3c is for releasing gas to the outside of the battery when the diaphragm 37 is cleaved by the gas pressure generated inside the battery.
When the lid 3 is made of iron, when joining in series with another cylindrical secondary battery, it may be joined with another cylindrical secondary battery made of iron by spot welding. Is possible.

The lid body 3, the diaphragm 37, the insulating plate 34, and the connection plate 35 are integrated to form a lid unit 30 (see FIG. 2). A method for assembling the lid unit 30 will be described below.
First, the lid 3 is fixed to the diaphragm 37. The diaphragm 37 and the lid 3 are fixed by caulking or the like. As shown in FIG. 2, since the side wall 37 b of the diaphragm 37 is initially formed perpendicular to the base portion 37 a, the peripheral edge portion 3 a of the lid 3 is disposed in the side wall 37 b of the diaphragm 37. Then, the side wall 37b of the diaphragm 37 is deformed by a press or the like, and the upper surface and the lower surface of the peripheral portion of the lid body 3 and the outer peripheral side surface are covered with pressure.

On the other hand, the connection plate 35 is fitted into the opening 34 a of the insulating plate 34 and attached. Next, with the insulating plate 34 sandwiched therebetween, the protrusion 35a of the connection plate 35 is welded to the bottom surface of the diaphragm 37 to which the lid 3 is fixed. As the welding method in this case, resistance welding or friction diffusion bonding can be used. As a result, the connecting plate 35 is welded to the diaphragm 37 fixed by the lid 3 with the insulating plate 34 interposed therebetween, so that the integrated lid unit 30 is configured.
As described above, the connecting plate 35 of the lid unit 30 is connected to the positive electrode current collecting member 27 by the connecting member 33. Therefore, the lid body 3 is connected to the positive electrode current collecting member 27. Thus, the lid 3 connected to the positive electrode current collecting member 27 acts as the other output end, and the lid 3 that acts as the other output end and the battery can 2 that acts as the one output end provide an electrode. It becomes possible to output the electric power stored in the group 10.

  Covering the peripheral edge of the side portion 37b of the diaphragm 37, a seal member 43, usually called a gasket, is provided. The seal member 43 is made of rubber, and is not intended to be limited, but an example of one preferable material is ethylene propylene copolymer (EPDM). For example, when the battery can 2 is made of carbon steel having a thickness of 0.5 mm and the outer diameter is 40 mmΦ, the thickness of the seal member 43 is about 1.0 mm.

  As shown in FIG. 2, the seal member 43 initially includes an outer peripheral wall portion 43 b that is formed on the peripheral side edge of the ring-shaped base portion 43 a so as to stand substantially vertically toward the upper direction, and an inner peripheral side. Further, it has a shape having a cylindrical portion 43c formed to hang substantially vertically downward from the base portion 43a.

  Then, the outer peripheral wall 43b of the seal member 43 is bent together with the battery can 2 by pressing or the like, and the diaphragm 37 and the lid 3 are crimped by the base 43a and the outer peripheral wall 43b so as to be pressed in the axial direction. Accordingly, the lid unit 30 in which the lid 3, the diaphragm 37, the insulating plate 34, and the connection plate 35 are integrally formed is fixed to the battery can 2 via the seal member 43.

A predetermined amount of non-aqueous electrolyte solution 44 is injected into the battery can 2. As an example of the nonaqueous electrolytic solution 44, it is preferable to use a solution in which a lithium salt is dissolved in a carbonate solvent. Examples of the lithium salt include lithium fluorophosphate (LiPF ₆ ), lithium fluoroborate (LiBF ₄ ), and the like. Examples of carbonate solvents include ethylene carbonate (EC), dimethyl carbonate (DMC), propylene carbonate (PC), methyl ethyl carbonate (MEC), or a mixture of solvents selected from one or more of the above solvents. Can be mentioned. The non-aqueous electrolyte 44 is usually injected about 1/5 to 1/3 of the capacity of the battery can 2.

Here, the insulating material that is a feature of the secondary battery of the present invention will be described.
The leading ends of a number of positive electrode leads 16 extending from the positive electrode mixture untreated portion 11 c formed along one side edge of the positive electrode 11 are welded together with the pressing member 28 to the upper cylindrical portion 27 c of the positive electrode current collecting member 27. Has been. FIG. 4 is an enlarged view of the cylindrical secondary battery 1 on the lid 3 side. As shown in the figure, the insulating material 51 is formed on the uppermost surface of the electrode group 10 from the lower end portion of the ring-shaped pressing member 28, that is, from the joint portion between the positive electrode lead 16 and the positive electrode current collecting member 27. It is formed so as to cover the upper surface of the positive electrode lead 16 in a continuous manner without interruption until the outer periphery (see FIG. 2). The upper surface of the electrode group 10 is almost entirely covered with the positive electrode lead 16 formed from the inner periphery side to the outer periphery side, and the insulating material 51 is covered on the entire surface of the positive electrode lead 16. In this case, if the upper surface of the electrode group 10 is not partially covered by the positive electrode lead 16 and the upper end portions of the first and second separators 13 and 14 are exposed from the upper surface of the electrode group 10, insulation is provided. The material 51 is coated on the entire surface of the positive electrode lead 16 including the exposed upper ends of the first and second separators 13 and 14.

  The leading ends of a large number of negative electrode leads 17 extending from the negative electrode mixture untreated portion 12 c formed along the other side edge of the negative electrode 12 are attached to the outer peripheral cylindrical portion 21 c of the negative electrode current collecting member 21 in a ring shape. 22 and welded together. FIG. 5 is an enlarged view of the can bottom side of the cylindrical secondary battery 1. As shown in the figure, the insulating material 51 is from the lower end of the holding member 22, that is, from the lower end of the joint between the negative electrode lead 17 and the negative electrode current collecting member 21, to the outermost periphery of the electrode group 10. It is formed so as to cover the upper surface of the negative electrode lead 17 in a continuous manner without interruption. The lower surface of the electrode group 10 is almost entirely covered with the negative electrode lead 17 formed from the inner peripheral side to the outer peripheral side, and the insulating material 51 is covered on the entire negative electrode lead 17. In this case, if the upper surface of the first and second separators 13 and 14 is exposed from the lower surface of the electrode group 10, the insulating layer is not partially covered by the negative electrode lead 17 on the lower surface of the electrode group 10. The material 51 is coated on the entire surface of the negative electrode lead 17 including the exposed lower ends of the first and second separators 13 and 14.

FIG. 6 is an enlarged view of the vicinity of the insulating material 51 formed on the positive electrode side. With reference to this figure, the covering structure of the positive electrode lead 16 by the insulating material 51 will be described in more detail.
As described with reference to FIG. 3, on the inner peripheral side and the outer peripheral side adjacent to the positive electrode mixture 11 b formed on both surfaces of the positive electrode sheet 11 a, the first and second separators 13 and 14 are interposed via the first and second separators 13 and 14. The negative electrode mixture 12b formed on both surfaces is opposed. On the positive electrode side, the end portion of the negative electrode mixture 12b is flush with the end portion of the negative electrode sheet 12a, and is positioned closer to the positive electrode current collector 27 than the end portion of the positive electrode mixture 11b. The dimension A from the portion to the end of the positive electrode mixture 11b is about 2 mm.

  The end portions of the first and second separators are located closer to the positive electrode current collecting member 27 than the end portions of the negative electrode 12, and the dimensions from the end portions of the first or second separator to the end portions of the negative electrode 12. B is about 2 mm. When the tip of the positive electrode lead 16 is welded to the positive electrode current collecting member 27, the positive electrode lead 16 is welded while being pulled toward the positive electrode current collecting member 27. For this reason, in actuality, it is inclined toward the first separator 13 side on the inner peripheral side, like a positive electrode lead 16 ′ illustrated by a dotted line in FIG. 6. For this reason, a gap between the positive electrode lead 16 and the second separator 14 on the outer peripheral side becomes large, and conductive foreign matter enters through this gap.

  The foreign material will be described. In the nonaqueous electrolytic solution 44 injected into the battery can 2, minute conductive foreign matter may be mixed. Such foreign matters are generated in the manufacturing process of the positive electrode sheet 11 and the negative electrode sheet 12, the processing process of the battery can 2, the welding process of the positive electrode lead 16 to the positive electrode current collecting member 27, and mixed in the non-aqueous electrolyte 44. To do. As described above, when a gap is generated between the positive electrode lead 16 and the second separator 14 adjacent to the outside thereof, the foreign matter generated in each of the above steps is removed from the positive electrode 11 and the second separator. Get in between 14.

  Since a predetermined potential, for example, 4.1 V, is applied between the positive electrode 11 and the negative electrode 12, foreign matter that has entered between the positive electrode 11 and the second separator 14 is ionized and penetrates the separator. It flows to the negative electrode 12 side. Then, it is deposited and grown on the negative electrode 12. This deposit causes a phenomenon in which the positive electrode and the negative electrode are short-circuited. For example, when the foreign material is copper which is the material of the negative electrode sheet 12a, such an internal short circuit may occur.

  Therefore, in the first embodiment of the present invention, from the lower end of the ring-shaped pressing member 28, that is, from the joint between the positive electrode lead 16 and the upper cylindrical portion 27 c of the positive electrode current collecting member 27, The insulating material 51 is formed in the entire region including the entire region up to the end of the second separator 14 adjacent to the outer periphery of the outermost positive electrode lead. In other words, the entire region from the innermost periphery of the positive electrode lead 16, which is the positive electrode exposed portion, exposed from one side surface of the electrode group 10 to the end of the separator adjacent to the outer periphery of the outermost positive electrode lead 16 is insulated. Covered with a material 51. Here, when a foreign substance enters between the outermost positive electrode lead 16 and the second separator 14 adjacent to the outer periphery, an internal short circuit occurs between the outermost negative electrode 12 and this region is insulated. It is necessary to cover with the material 51. In addition, although it is not necessary to cover with the insulating material 51 between the outermost 2nd separator 14 and the 1st outermost separator 13, as shown with the dashed-two dotted line in FIG. 6 from ease of manufacture. You may cover with insulating material 51 '.

FIG. 7 is an enlarged view of the vicinity of the insulating material 51 formed on the negative electrode side. As described above, for example, when foreign matter such as copper is generated from the negative electrode side, the foreign material circulates to the positive electrode side and enters between the positive electrode 11 and the second separator 14 to be ionized and deposited. A short circuit occurs. For this reason, in Embodiment 1 in the secondary battery of the present invention, the negative electrode side is also covered with the insulating material 51. The insulating material 51 has a lower end portion of the ring-shaped pressing member 22, that is, a joint portion between the negative electrode lead 17 and the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21, and an entire region from the outermost negative electrode lead 17 to The structure is formed over the entire region up to the end of the outermost first separator 13. In other words, the entire region extending from the innermost periphery to the outermost periphery of the negative electrode lead 17 that is the negative electrode exposed portion exposed from the other side surface of the electrode group 10 and the end of the separator on the outer periphery of the outermost negative electrode lead 17 are It is covered with an insulating material 51.
6 and 7, the outermost periphery of the electrode group 10 is the first separator 13, but the outermost separator is the second separator 14 by adjusting the length of the separator. Is also possible.

The insulating material 51 can be a polymer material selected from, for example, polyimide, polyester, and polyvinylidene fluoride. The insulating material 51 can be a material in which at least one of inorganic materials selected from alumina, zirconia , and titania is mixed with any of the polymer materials described above. Moreover, the insulating material 51 can also be comprised with the insulating material formation substance containing the synthetic resin chosen from at least one of a thermoplastic resin and thermosetting, or the mixed resin which mixed those resins.

  The insulating material 51 can be formed by a dipping method, a spraying method, or a coating method using centrifugal force. In the case of the application method by centrifugal force, the above-described liquid material is dropped in contact with the ring-shaped pressing member 22 or 28, and the power generation unit 20 is rotated at high speed. The liquid material extends due to the centrifugal force during high-speed rotation, and can cover up to the end of the outermost separator of the wound group 10.

(Modification 1 of insulating material covering structure)
FIG. 8 shows a first modification of the covering structure with the insulating material 51 and is a sectional view on the lid 3 side. In FIG. 4, the insulating material 51 is formed from the lower end of the pressing member 28 to the outermost periphery of the electrode group 10. On the other hand, in the first modification, the insulating material 51 covers almost the upper end surface of the pressing member 28. That is, the insulating material 51 covers the inner peripheral side of the electrode group 10 up to a position corresponding to the entire joint portion between the positive lead 16 and the upper cylindrical portion 27 c of the positive current collecting member 27.
4 and 8, the tip portion of the positive electrode lead 16 may be directly covered with the insulating material 51 as a structure in which the pressing member 28 is not used.

(Modification 2 of insulating material covering structure)
FIG. 9 is a cross-sectional view on the can bottom side, showing a second modification of the covering structure with the insulating material. In FIG. 5, the insulating material 51 is formed from the lower end of the pressing member 22 to the outermost periphery of the electrode group 10. On the other hand, in the modified example 2, the insulating material 51 covers almost the upper end portion of the pressing member 22. That is, the insulating material 51 covers the inner peripheral side of the electrode group 10 up to a position corresponding to the entire joint portion between the negative electrode lead 17 and the outer peripheral cylindrical portion 21 c of the negative electrode current collecting member 21.

(Modification 3 of insulating material covering structure)
FIG. 10 is a cross-sectional view on the can bottom side, showing a third modification of the covering structure with the insulating material. In the third modification, the inner peripheral side covering region by the covering material 51 is further expanded as compared with the second modification and covers the upper end surface of the holding member 22 and the upper end surface of the outer peripheral cylindrical portion 21c of the negative electrode current collecting member 21. .

FIG. 11 is a cross-sectional view on the can bottom side, showing a fourth modification of the covering structure with the insulating material. In the fourth modification, the inner peripheral side covering region by the covering material 51 is further expanded as compared with the third modification and covers the inner surface of the outer peripheral cylindrical portion 21 c of the negative electrode current collecting member 21.
As described above, the negative electrode side acts as a foreign matter generation source with respect to the internal short circuit. When minute foreign matter or ionized foreign matter is generated from the negative electrode side, it is deposited on the positive electrode side. Modification 3 or 4 Since the occurrence of such foreign matter is prevented, the probability of occurrence of an internal short circuit is further reduced.
In FIGS. 5 and 9 to 11, the tip of the negative electrode lead 17 may be directly covered with the insulating material 51 as a structure that does not use the pressing member 22.
Next, the manufacturing method of the cylindrical secondary battery shown in Embodiment 1 is demonstrated with reference to the processing flow of FIG.

(Method for manufacturing secondary battery)
[Production of electrode group]
First, as shown in step S1, the electrode group 10 is produced. A positive electrode 11 is produced in which a positive electrode mixture 11b and a positive electrode mixture untreated portion 11c are formed on both surfaces of the positive electrode sheet 11a, and a large number of positive electrode leads 16 are integrally formed on the positive electrode sheet 11a. Moreover, the negative electrode mixture 12b and the negative electrode process part 12c are formed in both surfaces of the negative electrode sheet 12a, and the negative electrode 12 by which many negative electrode leads 17 were integrally formed in the negative electrode sheet 12a is produced.

  Next, the innermost side edge portions of the first separator 13 and the second separator 14 are welded to the shaft core 15. Next, the first separator 13 and the second separator 14 are wound around the shaft core 1 to several times, the negative electrode 12 is sandwiched between the second separator 14 and the first separator 13, a predetermined angle, The shaft core 15 is wound. Next, the positive electrode 11 is sandwiched between the first separator 13 and the second separator 14. In this state, the electrode group 10 is manufactured by winding a predetermined number of turns.

[Production of power generation unit]
Next, as shown in step S2, the power generation unit 20 is created. The negative electrode current collecting member 21 is attached to the lower part of the axial core 15 of the electrode group 10 produced by the above-described method.
The negative current collector 21 is attached by fitting the opening 21 b of the negative current collector 21 into a step portion 15 b provided at the lower end of the shaft 15. Next, the negative electrode lead 17 is distributed almost uniformly around the entire outer periphery of the outer peripheral cylindrical portion 21 c of the negative electrode current collecting member 21, and the pressing member 22 is wound around the outer periphery of the negative electrode lead 17. Then, the negative electrode lead 17 and the pressing member 22 are welded to the negative electrode current collecting member 21 by ultrasonic welding or the like. Next, the negative electrode conducting lead 23 is welded to the negative electrode current collecting member 21 so as to straddle the lower end surface of the shaft core 15 and the negative electrode current collecting member 21.

  Next, one end of the connection member 33 is welded to the base 27a of the positive electrode current collector 27 by, for example, ultrasonic welding. Next, the lower cylindrical portion 27 b of the positive electrode current collecting member 27 to which the connecting member 33 is welded is fitted into a groove 15 a provided on the upper end side of the shaft core 15. In this state, the positive electrode lead 16 is distributed almost uniformly around the entire outer periphery of the upper cylindrical portion 27 c of the positive electrode current collecting member 27, and the pressing member 28 is wound around the outer periphery of the positive electrode 16. Then, the positive electrode lead 16 and the pressing member 28 are welded to the positive electrode current collecting member 27 by ultrasonic welding or the like. In this way, the power generation unit 20 illustrated in FIG. 2 is produced.

[Insulation coating]
Next, as shown in step S <b> 3, the insulating material 51 is deposited on the positive electrode lead 16 and the negative electrode lead 17. As the insulating material 51, for example, a polypropylene solution having a melting point of 100 to 120 ° C. is used. This solution is hung so as to contact at least the lower end portion of the pressing member 28, and the power generation unit 20 is rotated at a high speed. As a result, the insulating material solution extends over the entire upper portion of the power generation unit 20 and can cover up to the ends of the first and second separators 13 and 14 on the outer periphery of the positive electrode lead 16. After the insulating material solution is cured at room temperature to form the insulating material 51, the insulating material 51 is formed on the negative electrode side in the same manner. However, in this case, since there is a step of welding the negative electrode conductive lead 23 to the bottom of the battery can 2 thereafter, the insulating material 51 is not applied on the negative electrode conducting lead 23 which becomes an obstacle to the welding. There is a need.

  If the insulating material 51 has a large heat capacity or a high melting point, it adversely affects the battery characteristics during curing. For this reason, the thing with small heat capacity and low melting | fusing point is desirable. However, it cannot be adopted when there is a process in which the insulating film 51 is heated to near the melting point after the insulating film 51 is formed. In the present embodiment, a manufacturing method is employed in which the insulating film 51 is not heated to around 100 ° C. in the subsequent steps. Therefore, it is possible to use a low melting point insulating material solution having a melting point of 100 to 120 ° C.

[Containment in battery can]
On the other hand, separately from the production of the power generation unit 20, the battery can 2 is produced. The battery can 2 is plated on the entire outer and inner surfaces. The battery can 2 is drawn to a predetermined depth by drawing a circular metal plate several times.
Then, as shown in step S <b> 4, the power generation unit 20 in which the insulating material 51 is formed is accommodated in the battery can 2.

[Negative electrode bonding]
Next, as shown in step S <b> 5, the negative electrode conducting lead 23 of the power generation unit 20 accommodated in the battery can 2 is welded to the bottom of the battery can 2 by resistance welding or the like. In this step, although not shown, an electrode rod is inserted from the opening 27e of the positive electrode current collecting member 27, the hollow portion of the shaft core 15 is inserted, and the negative electrode energizing lead 23 is pressed against the bottom of the battery can 2 and welded. To do. In this case, since the insulating material 51 is not applied to the outer surface of the negative electrode conducting lead 23, the insulating material 51 does not become an obstacle to welding. Further, since the negative electrode conducting lead 23 having a small area is welded, the insulating material 51 is not heated to 70 ° C. or higher.

[Grooving]
Next, as shown in step S6, a part on the upper end side of the battery can 2 is grooved (drawn) and protrudes inward to form a substantially U-shaped groove 2a on the outer surface. The groove 2 a of the battery can 2 is formed so as to be positioned in the upper end portion of the power generation unit 20, in other words, in the vicinity of the upper end portion of the positive electrode current collecting member 27.

[Injection of electrolyte]
Next, as shown in step S <b> 7, a predetermined amount of nonaqueous electrolyte solution 44 is injected into the battery can 2 in which the power generation unit 20 is accommodated. As described above, for example, a solution in which a lithium salt is dissolved in a carbonate solvent is used as the nonaqueous electrolytic solution 44. The injection amount is about 1/5 to 1/3 of the capacity of the battery can 2.

[Sealing]
On the other hand, a lid unit 30 is prepared separately from the assembly process for the battery can 2.
As described above, the lid unit 30 includes the insulating plate 34, the connecting plate 35 fitted into the opening 34a of the insulating plate 34, the diaphragm 37 welded to the connecting plate 35, and the lid 3 fixed to the diaphragm 37 by caulking. It is comprised by. The manufacturing method of the lid unit 30 is as described above.

When the lid unit 30 is manufactured, the electrode group 10 and the lid unit 30 are electrically connected. First, the seal member 43 is placed on the groove 2 a of the battery can 2. As shown in FIG. 2, the seal member 43 in this state has a structure having an outer peripheral wall 43b perpendicular to the base 43a above the ring-shaped base 43a.
Then, one end portion of the lead plate 33 is joined to the upper surface of the base portion 27a of the positive electrode current collecting member 27 accommodated in the battery can 2 by ultrasonic welding or the like.
Next, the above-described lid unit 30 is joined to the other end portion of the lead plate 33 in such a state.
The other end side of the lead plate 33 is folded back, and the connection plate 35 of the lid unit 30 is held in contact with the other end portion of the lead plate 33 folded by a holder (not shown), and the laser is applied to the contact portion. Irradiate and laser weld. In this case, the joining surface of the other end portion of the lead plate 33 joined to the connection plate 35 of the lid unit 30 is on the same side as the joining surface of one end portion joined to the base portion 27a of the positive electrode current collecting member 27. . In the connection process between the electrode group 10 and the lid unit 30, the welding area of the lead plate 30 is small, so that the heating temperature of the insulating material 51 can be suppressed to 70 ° C. or less.

  Then, as shown in step S8, the battery unit 30 is accommodated in the battery can 2, and the battery can 2 and the battery unit 30 are caulked to be sealed from the outside. Thereby, the cylindrical secondary battery 1 shown in FIG. 1 is completed.

Since the cylindrical secondary battery 1 manufactured in this way has the insulating material 51 formed not only on the positive electrode lead 16 but also on the end of the separator on the outer periphery of the outermost positive electrode lead 16. An internal short circuit can be prevented without foreign matter entering the electrode 11.
Further, since the insulating material 51 is formed not only on the negative electrode lead 17 but also on the end portion of the separator adjacent to the outer periphery of the outermost negative electrode lead 17, foreign matter is introduced into the non-aqueous electrolyte 44 from the negative electrode side. It can be prevented from flowing out, so that it can be prevented from being deposited on the positive electrode side and causing an internal short circuit.
As the insulating material 51, a low-melting-point material such as polypropylene can be used, and the battery characteristics are not adversely affected.

  In addition, in the said embodiment, although it is the structure which provided the insulating material 51 in both the positive electrode side and the negative electrode side, you may make it provide the insulating material 51 only in either one side. As described above, the occurrence of foreign matter changes depending on conditions such as the manufacturing process of the positive electrode sheet 11 and the negative electrode sheet 12, the processing process of the battery can 2, the welding process of the positive electrode lead 16 to the positive electrode current collecting member 27, etc. The region covered with the insulating material 51 may be determined according to the state of occurrence.

--Embodiment 2-
13 and 14 show Embodiment 2 of the secondary battery of the present invention. FIG. 13 is a cross-sectional view of the entire cylindrical secondary battery 1A, and FIG. 14 is a plan view of the power generation unit 20 viewed from the lid 3 side with the battery unit 30 in FIG. 13 removed.
The cylindrical secondary battery 1A of the second embodiment is different from the cylindrical secondary battery 1 of the first embodiment in that the insulating material 51 has a circular shape in which the positive electrode lead 16 or the negative electrode lead 17 in the power generation unit 20 is disposed. It is a point provided not in the entire circumference of the side surface but only in a part of the region. Other configurations are the same as those of the first embodiment, and the corresponding members are denoted by the same reference numerals and description thereof is omitted.
The cylindrical secondary battery 1A of the second embodiment is of a horizontal type in which the axial direction of the cylindrical secondary battery 1A is oriented in the horizontal direction.
In this case, the nonaqueous electrolyte solution 44 injected into the battery can 2 has a depth from the lowermost surface of the battery can 2 that is less than half the diameter of the battery can 2. In the illustrated example, the depth of the nonaqueous electrolytic solution 44 is about 1/5 of the diameter of the battery can 2.

  In such a state, the regions on the positive electrode side and the negative electrode side that are immersed in the nonaqueous electrolytic solution 44 are extremely limited. Therefore, as shown in FIG. 14, the insulating material 51 provided on the positive electrode side and the negative electrode side is not the entire circumference where the positive electrode lead 16 or the negative electrode lead 17 is provided, but slightly above the depth of the non-aqueous electrolyte 44. Only a part of the area up to the side.

  Moreover, the mark 61 is attached | subjected to the upper surface side of the cylindrical part of the battery can 2, in other words, the opposite surface side to the side where the nonaqueous electrolyte solution 44 retains. The mark 61 is for clearly indicating the regions of the positive electrode lead 16 and the negative electrode lead 17 that are immersed in the nonaqueous electrolytic solution 44, in other words, the position where the insulating material 51 is provided. When installing the cylindrical secondary battery 1 </ b> A, the operator recognizes the position where the insulating material 51 is provided by the mark 61, and the internal non-aqueous electrolyte 44 stays at the position where the insulating material 51 is provided. Thus, the orientation of the cylindrical secondary battery 1A can be adjusted. The mark 61 may be attached to the battery can 2 as a label, or may be displayed directly on the battery can 2 by laser irradiation or printing.

The cylindrical secondary battery 1 </ b> A of the second embodiment having the above configuration also has the same effect as the cylindrical secondary battery 1 of the first embodiment.
In the second embodiment, the insulating material 51 may be provided only on one of the positive electrode side and the negative electrode side.
Also in the second embodiment, the structure of the first to fourth modifications shown in the first embodiment can be applied to the structure of the insulating material 51a.

--Embodiment 3--
15 and 16 show Embodiment 3 of the secondary battery of the present invention. 15 is a cross-sectional view of the cylindrical secondary battery 1B on the lid 3 side, and FIG. 16 is an insulating material that covers the power generation unit 20 and the circular side surface on which the positive electrode lead 16 of the power generation unit 20 is disposed. It is a perspective view of 51B.
The cylindrical secondary battery 1B of the third embodiment is different from the cylindrical secondary battery 1 of the first embodiment in that the insulating material 51A is formed of a resin molded body. Other configurations are the same as those of the first embodiment, and the corresponding members are denoted by the same reference numerals and description thereof is omitted.

In the third embodiment, the insulating material 51A is formed as a cap-shaped resin molded body 53 having an inner surface coated with an adhesive 52.
As the material of the adhesive 52, the material of the insulating material 51 exemplified in the first embodiment can be applied. The resin molded body 53 has a shape corresponding to the shape of the positive electrode lead 16 disposed on the circular side surface on the positive electrode side in the power generation unit 20. On the bottom side of the resin molded body 53, an opening 53a that accommodates up to the end of the separator on the outer periphery of the outermost positive electrode lead 16 is formed. In addition, an opening 53 b having a size in contact with the outer peripheral surface of the ring-shaped pressing member 28 is formed on the upper side of the resin molded body 53. The inner surface of the resin molded body 53 has a shape in contact with the upper surface of the positive electrode lead 16 welded to the upper cylindrical portion 27 c of the positive electrode current collecting member 27.

In order to cover the positive electrode lead 16 side with the insulating material 51A, an adhesive 52 is applied to the inner surface of the resin molded body 53, and the resin 52 is applied to the end of the positive electrode lead 16 and its outer separator with the adhesive 52 uncured. The molded body 53 may be pressed and the adhesive 52 may be cured in that state.
In this case, it is necessary to pay particular attention so that there is no gap between the inner surface of the resin molded body 53 on the opening 53a side and the opening 53b side between the gap positive electrode lead 17 and the end of the separator.

  The cylindrical secondary battery 1 </ b> B of the third embodiment also has the same effects as the cylindrical secondary battery 1 of the first embodiment. In particular, in the third embodiment, the adhesive 52 applied to the inner surface of the resin molded body 53 is simply an operation for pressing the positive electrode lead 17 and the end of the separator. Work becomes efficient.

Although only the positive electrode side has been described above, similarly, the insulating material 51A can be provided also on the negative electrode side.
The height of the resin molded body 53 can be appropriately changed as in the region covered by the structure of the first to fourth modifications shown in the first embodiment.

  In each of the above embodiments, the case where the lid unit 30 is configured by the lid body 3, the diaphragm 37, the insulating plate 34, and the connection plate 35 has been described. However, the configuration of the lid unit 30 is an example, and other configurations may be employed. Further, the lid is not unitized, and may be a single unit as long as it is an electrode terminal member having a function as an electrode terminal.

  In the above embodiments, the lithium ion cylindrical secondary battery has been described as an example. However, the secondary battery of the present invention can also be applied to a prismatic secondary battery. In the case of a prismatic secondary battery, the electrode group has a flat portion and a flat shape in which arc-shaped portions having a semicircular cross section are connected to both sides of the flat portion. Moreover, the lead | read | reed pulled out outward is not formed in the positive electrode exposed part which is a positive electrode mixture untreated part, and the negative electrode exposed part which is a negative electrode mixture untreated part. In such an electrode group, insulation is performed on all positive electrode exposed portion ends and separator end portions forming one side surface and / or on negative electrode exposed portion end portions and separator end portions forming the other side surface. A structure covered with a material may be used.

  In the above embodiment, a lithium ion cylindrical secondary battery using a non-aqueous electrolyte solution has been described as an example of the battery. However, the present invention is not limited to a lithium battery, but a nickel metal hydride battery or a nickel cadmium battery. The present invention can also be applied to other cylindrical secondary batteries using a water-soluble electrolyte.

  In addition, the sealing structure of the secondary battery of the present invention can be variously modified and configured within the scope of the invention. In short, the positive electrode exposed portion formed along one side edge. An electrode group in which a sheet-like positive electrode having a negative electrode and a sheet-like negative electrode having a negative electrode exposed portion formed along the other side edge are wound from the inner periphery to the outer periphery via a sheet-like separator And a positive electrode current collecting member to which the positive electrode exposed portion of the positive electrode is bonded, a negative electrode current collecting member to which the negative electrode exposed portion of the negative electrode is bonded, an electrode group, a positive electrode current collecting member, and a negative electrode current collecting member are accommodated, A battery can into which an electrolyte is injected, and an insulating material covering at least one predetermined region of the positive electrode exposed portion exposed from one side surface of the electrode group or the negative electrode exposed portion exposed from the other side surface of the electrode group. The insulating material is exposed to the positive electrode from the innermost circumference to the outermost circumference. Others may be one covering comprises an end portion of the separator adjacent to the outer periphery of the positive electrode exposed portion or the negative electrode exposed portion with the negative electrode exposed portion.

DESCRIPTION OF SYMBOLS 1, 1A, 1B Cylindrical secondary battery 2 Battery can 3 Cover body 10 Electrode group 11 Positive electrode 11a Positive electrode sheet 11b Positive electrode mixture 11c Positive electrode mixture untreated part (positive electrode exposed part)
12 Negative electrode 12a Negative electrode sheet 12b Negative electrode mixture 12c Negative electrode mixture untreated part (negative electrode exposed part)
DESCRIPTION OF SYMBOLS 13 1st separator 14 2nd separator 16 Positive electrode lead 17 Negative electrode lead 20 Power generation unit 21 Negative electrode current collection member 27 Positive electrode current collection member 30 Lid unit 44 Non-aqueous electrolyte 51, 51A Insulation material 52 Adhesive 53 Resin molding

Claims (9)

A sheet-like positive electrode having a positive electrode exposed portion formed along one side edge and a sheet-like negative electrode having a negative electrode exposed portion formed along the other side edge are disposed through a sheet-like separator. A group of electrodes wound from the periphery to the periphery;
A positive electrode current collecting member to which the positive electrode exposed portion of the positive electrode is bonded;
A negative electrode current collecting member to which the negative electrode exposed portion of the negative electrode is bonded;
A battery can in which the electrode group, the positive electrode current collecting member and the negative electrode current collecting member are accommodated, and an electrolyte is injected;
An insulating material covering a predetermined region of at least one of the positive electrode exposed portion exposed from one side surface of the electrode group or the negative electrode exposed portion exposed from the other side surface of the electrode group;
The insulating material covers the positive electrode exposed portion or the negative electrode exposed portion extending from the innermost periphery to the outermost periphery including the end portion of the separator adjacent to the outer periphery of the positive electrode exposed portion or the negative electrode exposed portion. Secondary battery characterized.   The secondary battery according to claim 1, wherein the electrode group and the battery can have a cylindrical shape, the positive electrode exposed portion includes a plurality of positive electrode leads, the negative electrode exposed portion includes a negative electrode lead, The insulating material is formed on at least one of the predetermined region on the positive electrode lead including the end portion of the separator exposed from the one side edge side or on the negative electrode lead including the end portion of the separator exposed from the other side edge. A secondary battery characterized in that it is formed in a continuous state without any interruption.   3. The secondary battery according to claim 1, wherein the insulating material covers both the positive electrode exposed portion exposed from the electrode group and the negative electrode exposed portion exposed from the electrode group. Secondary battery. 4. The secondary battery according to claim 1, wherein the insulating material is a part of the positive electrode exposed part exposed from the electrode group or a part of the negative electrode exposed part exposed from the electrode group. 5. A secondary battery characterized by covering only.   4. The secondary battery according to claim 1, wherein the insulating material is exposed from all of the positive electrode exposed portion and the end portion of the separator exposed from the electrode group, and from the electrode group. 5. Further, the secondary battery covers all of the negative electrode exposed portion and the end portion of the separator.   6. The secondary battery according to claim 1, wherein the insulating material is a molded body in which an adhesive bonded to the positive electrode exposed portion or the negative electrode exposed portion is provided on an inner surface. 7. Secondary battery characterized. The secondary battery according to any one of claims 1 to 6, wherein the insulating material is a polymer material selected from polyimide, polyester, and polyvinylidene fluoride, or any one of the polymer materials, alumina, A secondary battery comprising a material in which at least one of inorganic materials selected from zirconia and titania is mixed. The secondary battery according to any one of claims 1 to 6, wherein the insulating material is a synthetic resin selected from at least one of a thermoplastic resin and a thermosetting resin, or a mixed resin obtained by mixing these resins. A secondary battery comprising an insulating material-forming substance containing   9. The secondary battery according to claim 1, wherein the insulating material is formed by any one of an immersion method, a spraying method, and a coating method using centrifugal force. Secondary battery.

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