WO2012053556A1 - Non-aqueous electrolyte secondary cell - Google Patents

Non-aqueous electrolyte secondary cell Download PDF

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Publication number
WO2012053556A1
WO2012053556A1 PCT/JP2011/074062 JP2011074062W WO2012053556A1 WO 2012053556 A1 WO2012053556 A1 WO 2012053556A1 JP 2011074062 W JP2011074062 W JP 2011074062W WO 2012053556 A1 WO2012053556 A1 WO 2012053556A1
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Prior art keywords
positive electrode
negative electrode
exposed portion
tab
core exposed
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PCT/JP2011/074062
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French (fr)
Japanese (ja)
Inventor
吉田　聡司
大下　竜司
秀行 猪俣
和幸 川上
濱田　拓哉
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三洋電機株式会社
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Publication of WO2012053556A1 publication Critical patent/WO2012053556A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/534—Electrode connections inside a battery casing characterised by the material of the leads or tabs
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a non-aqueous electrolyte secondary battery, and more specifically, a non-aqueous electrolyte secondary battery in which the generation of a magnetic field due to a current flow during use is small and the influence of noise caused by the magnetic field on a hearing aid or the like is small. It relates to batteries.
  • non-aqueous electrolyte secondary batteries represented by high-capacity lithium ion secondary batteries are widely used.
  • These non-aqueous electrolyte secondary batteries generally include a positive electrode in which a positive electrode mixture containing a positive electrode active material that absorbs and releases lithium ions is applied to both surfaces of a positive electrode core made of an elongated sheet-like aluminum foil, and an elongated sheet.
  • the separator is made of and wound into a cylindrical or elliptical shape with the positive electrode and the negative electrode insulated from each other by the separator to form a wound electrode body.
  • the wound electrode body is further crushed and flattened.
  • a positive electrode tab and a negative electrode tab are connected to predetermined portions of the positive electrode and the negative electrode, respectively, and the outside is covered with an exterior.
  • the positive electrode tab or the negative electrode tab is electrically connected by ultrasonic welding, resistance welding or pressure welding (including pressure bonding) to the exposed portion of the positive electrode core or negative electrode core, respectively. It is connected to the.
  • An example of a configuration for electrically connecting such a conventional positive electrode tab or negative electrode tab to the exposed portion of the positive electrode core or negative electrode core will be described with reference to FIG.
  • FIG. 5 is a plan view showing a configuration of a positive electrode tab or a negative electrode tab disclosed in Patent Document 1 below.
  • An electrode 50 shown in Patent Document 1 below has a structure in which an electrode material layer 52 is formed on a core body 51 and an electrode tab 54 made of a metal lead is resistance-welded to an electrode material layer non-formed portion 53. And the contact resistance between the core 51 and the electrode tab 54 is increased by forming an uneven portion having an average diameter of 0.5 ⁇ m or more and 10.0 ⁇ m or less on the surface of the electrode tab 54. A good welding spot point 55 is formed, and a decrease in welding strength and displacement between the core 51 and the electrode tab 54 can be suppressed. According to the electrode disclosed in Patent Document 1, there is an effect that resistance welding between the core and the electrode tab can be performed more firmly and reliably.
  • the hearing aid has a function of capturing and amplifying external sound with a microphone, and a function of capturing and amplifying magnetic flux generated from the speaker portion of the telephone by an electromagnetic coil with an electromagnetic pickup (also referred to as “telephone pickup”). In particular, it is easily affected by external magnetic field noise.
  • an electromagnetic pickup also referred to as “telephone pickup”. The reason why the hearing aid uses such an electromagnetic pickup is that when the sound output from the speaker of the telephone is picked up and amplified by the microphone of the hearing aid, ambient noise is picked up by the microphone, so that the clarity of the sound is lowered. Because.
  • the magnetic field generated from the mobile phone tends to adversely affect the hearing aid. For this reason, even in a non-aqueous electrolyte secondary battery that is a power source of a mobile phone, it is desired to suppress the generation of a magnetic field due to the current flowing through the non-aqueous electrolyte secondary battery.
  • the magnetic field caused by the current flowing in the active material formation region of the positive electrode plate and the negative electrode plate has the positions of the positive electrode tab or the negative electrode tab both on the winding start side or the winding end side of each electrode plate and overlap each other. Or if it arrange
  • the positions of the positive electrode tab and the negative electrode tab are arranged at positions overlapping each other, it is difficult to electrically insulate and attach each tab, so that it is difficult to adopt immediately.
  • the positive electrode plate has a positive electrode tab attached to the winding end side and the negative electrode plate has a negative electrode tab attached to the winding start side
  • a current whose current value sequentially increases on the right side flows, and on the negative electrode side, a current whose current value decreases sequentially from the left side to the right side.
  • the current flowing in the positive electrode active material forming region of the positive electrode plate is parallel and in the same direction as the current flowing in the negative electrode active material forming region of the negative electrode plate, so that the magnetic field caused by the current flowing through the battery is increased.
  • the current flowing through the positive electrode active material forming region of the positive electrode plate is parallel and opposite to the current flowing through the negative electrode active material forming region of the negative electrode plate, so that the magnetic fields caused by the current flowing through the battery cancel each other.
  • welding of the positive electrode tab or the negative electrode tab is performed at a plurality of spots in a spot manner as is apparent from the description of FIG. It is not performed uniformly throughout. Therefore, in the vicinity of the welding location, the current flowing through the core body portion flows in a complicated direction at each welding location, so that various magnetic fields are generated. In addition, when the end of the active material formation region and the tab welding position are close, the current flow becomes more complicated and becomes a factor that a magnetic field is easily generated. Therefore, there is room for further improvement in the attachment structure of the positive electrode tab or the negative electrode tab in order to suppress the generation of a magnetic field due to the current flowing in the nonaqueous electrolyte secondary battery.
  • the inventors have made various studies to solve the above-mentioned problems, and as a result, the welding positions of the positive electrode tab or the negative electrode tab are both set to the winding start side or the winding end side of the electrode plate, and the positive electrode tab or the negative electrode.
  • the width of each core exposed portion forming the tab and welding the positive electrode tab or the negative electrode tab to the core exposed portion the generation of the magnetic field due to the current flowing in the battery can be extremely reduced.
  • the present inventors have found out what can be done and have completed the present invention.
  • Patent Document 2 in a positive electrode plate or negative electrode plate 60 in which an active material layer 62 is formed on a current collector (core body) 61 of a lithium ion polymer battery.
  • the electrode lead (current collecting tab) 63 is an example in which an active material layer non-formation portion 64 of the core body 61 is cut and bent, and the electrode lead (current collection tab) 63 is formed of the bent portion.
  • Patent Document 3 an electrode body (not shown) in which a positive electrode plate 71 and a negative electrode plate 72 are wound in a state of being insulated from each other via a separator 73 is provided.
  • a positive electrode tab 76 is welded to the positive electrode core exposed portion 75 of the positive electrode plate 71 where the positive electrode active material layer 74 is not formed, and a negative electrode active material layer 77 of the negative electrode plate 73 is formed.
  • An example in which the negative electrode core exposed portion 78 has a negative electrode tab 79 formed by cutting and bending a part of the terminal end of the negative electrode core exposed portion 78 in the width direction of the negative electrode core exposed portion 78 more than 1/2. It is shown.
  • Reference numerals 80a to 80d are insulating tapes.
  • Patent Documents 2 and 3 do not consider anything about the generation of a magnetic field due to the current flowing in the battery, and the positive electrode core exposed portion or the width of the active material layer forming region is the same as the width of the active material layer forming region.
  • a negative electrode core exposed portion is formed, and there is no suggestion about the problem of generation of a magnetic field due to the presence of the positive electrode core exposed portion or the negative electrode core exposed portion having the same width as the active material layer forming region. It has not been.
  • an object of the present invention is to provide a non-aqueous electrolyte secondary battery in which generation of a magnetic field due to a current flow during use is small and the influence of noise due to the magnetic field on a hearing aid or the like is reduced.
  • the nonaqueous electrolyte secondary battery of the present invention includes a positive electrode plate in which a positive electrode mixture layer is applied to both surfaces of a positive electrode core, and a negative electrode active material layer applied to both surfaces of the negative electrode core.
  • a flat wound electrode body wound with a separator sandwiched between each of the negative electrode plates, an exterior body housing the flat wound electrode body, and nonaqueous electrolysis injected into the exterior body A positive electrode core having a width shorter than 1 ⁇ 2 of the width of the positive electrode plate on the winding start side or the winding end side of the positive electrode plate.
  • An exposed portion is formed, and a positive electrode tab is welded or pressed to the exposed portion of the positive electrode core, and the negative electrode plate is disposed on the same side as the exposed portion of the positive electrode core on the same side as the 1 / width of the negative electrode plate.
  • a negative electrode core exposed portion having a width shorter than 2 is formed, and the positive electrode core exposed portion and the negative electrode core exposed portion It faces through the separator, and a negative electrode tab is welded or pressed to the negative electrode core exposed portion, and the positive electrode tab and the negative electrode tab are in a winding axis direction of the wound electrode body. It is derived in the same direction.
  • the welding point or the pressure contact of the positive electrode tab and the negative electrode tab is composed of welding means or pressure welding means such as a known resistance welding apparatus, ultrasonic welding apparatus, laser welding apparatus, etc., and the positive electrode tab or the negative electrode tab is exposed to the positive electrode core. It is not formed uniformly over the entire surface in contact with the portion or the negative electrode core exposed portion, but is formed partially.
  • the nonaqueous electrolyte secondary battery is manufactured such that the area of the negative electrode plate is larger than that of the positive electrode plate in order to suppress generation of lithium dendrite in the negative electrode plate.
  • the current flowing from each active material layer forming region side tends to flow at the shortest distance to the welding point or pressure contact of each electrode tab, but at least the negative electrode plate
  • a component flows from the lower negative electrode active material layer side to the upper side of the battery (the side where the negative electrode tab is formed). This component tends to become prominent when the distance between the end of the negative electrode active material layer forming region and the negative electrode tab is short.
  • the magnetic field formed by the current flowing upward from the lower negative electrode active material layer side on the negative electrode plate side is not canceled by the magnetic field formed by the current flowing through the positive electrode plate. Will be adversely affected.
  • the positive electrode plate has a positive electrode core exposed portion having a width shorter than 1 ⁇ 2 of the width of the positive electrode plate on the winding start side or winding end side of the positive electrode plate.
  • a positive electrode tab is welded or pressed to the exposed portion of the positive electrode core, and the negative electrode plate is on the same side as the exposed portion of the positive electrode core, and is less than half the width of the negative electrode plate.
  • a negative electrode core exposed portion with a short width is formed so as to face the positive electrode core exposed portion via the separator, and a negative electrode tab is welded or pressed to the negative electrode core exposed portion.
  • the tab and the negative electrode tab are led out in the same direction with respect to the winding axis direction of the wound electrode body. Therefore, according to the nonaqueous electrolyte secondary battery of the present invention, the current flowing through the positive electrode tab or the negative electrode tab through the positive electrode core exposed portion or the negative electrode core exposure is concentrated on the upper side of the battery, and the directions are opposite to each other. In addition, since the current flows in parallel, the magnetic fields caused by the currents flowing through the positive electrode plate and the negative electrode plate cancel each other, so that the magnetic field can be reduced.
  • the width of the positive electrode core exposed portion or the width of the negative electrode core exposed portion is 1 ⁇ 2 or more of the width of each electrode plate, the current flowing based on the difference in area between the positive electrode plate and the negative electrode plate Since a difference occurs in the direction, the magnetic fields cannot cancel each other, which is not preferable. Therefore, in the nonaqueous electrolyte secondary battery of the present invention, the width of the positive electrode core exposed portion or the width of the negative electrode core exposed portion provided in the prior art is the same as the width of the positive electrode plate or the negative electrode plate. It is essential not to.
  • the positive electrode tab and the negative electrode tab are wound electrode bodies because an effect is obtained if the current flowing in the positive electrode plate and the current flowing in the negative electrode plate flow in opposite directions. It may be provided on the winding start side or on the winding end side.
  • the core body exposed portion of the electrode having the same polarity as the polarity of the exterior body is used from the viewpoint of preventing a short circuit. It is preferable to arrange
  • the length of the core exposed portion of the electrode disposed on the outermost periphery of the wound electrode body is preferably longer than the length of the core exposed portion of the opposite electrode, and further the portion where the tab is attached. Considering the strength, it is preferably at least 1/2 of the length of the outer circumference of the wound electrode body. However, if the length is too long, the battery capacity may be reduced. The following is preferable.
  • the lengths of the positive electrode core exposed part and the negative electrode core exposed part are the innermost circumference of the wound electrode body. It is preferable that the length is about 1/4 to 1/2 of the length of one circle. If it is too short, the strength of the core exposed portion may be insufficient, and if it is too long, the battery capacity may be reduced.
  • the electrode tab provided in the core body exposed portion of one electrode plate is opposed to one electrode plate having the same polarity.
  • the core exposed portion of either the positive electrode plate or the negative electrode plate is formed in advance so as to be longer than the other core exposed portion, and the winding start timing is set as the positive electrode when the wound electrode body is manufactured. Shift it with the negative electrode, start winding one electrode plate with a long core exposed portion first, wind up the tab welded portion in one core exposed portion, and then start winding the other electrode plate together This can be easily achieved.
  • a transition metal can be substituted with another element, or another element can be added alone or as a compound.
  • the negative electrode active material used for the negative electrode at least one selected from the group consisting of a carbonaceous material, a siliconaceous material and a metal oxide capable of inserting and extracting lithium can be used.
  • a carbonaceous material that has been graphitized is particularly preferable because of its high capacity.
  • Nonaqueous solvents that can be used in the nonaqueous electrolyte of the nonaqueous electrolyte secondary battery of the present invention include cyclic carbonates, chain carbonates, esters, cyclic ethers, chain ethers, nitriles, amides, etc. Is mentioned.
  • the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate and the like, and those in which some or all of these hydrogen groups are fluorinated can also be used.
  • trifluoropropylene Carbonate and fluoroethylene carbonate can be used.
  • chain carbonate symmetric chain carbonates such as dimethyl carbonate and diethyl carbonate
  • asymmetric chain carbonates such as ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, and methyl isopropyl carbonate
  • Those in which part or all of these hydrogens are fluorinated can also be used.
  • the electrolyte constituting the organic electrolyte is lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), trifluoromethyl.
  • lithium salts such as lithium sulfonate (LiCF 3 SO 3 ) and lithium bistrifluoromethylsulfonylimide [LiN (CF 3 SO 2 ) 2 ].
  • LiPF 6 and LiBF 4 are preferably used, and the amount dissolved in the organic solvent is preferably 0.5 to 2.0 mol / L.
  • the nonaqueous electrolyte can be used not only in a solution state but also in a gelled state.
  • the positive electrode core exposed portion and the negative electrode core exposed portion are formed at the center of the width of the wound electrode body because the magnetic field in the vicinity of the core exposed portion tends to be small.
  • welding between the positive electrode core exposed portion and the positive electrode tab and welding between the negative electrode core exposed portion and the negative electrode tab are performed by resistance welding. Or it is preferable that it was what was performed by the ultrasonic welding method.
  • Laser welding can be used for welding between the positive electrode core exposed portion and the positive electrode tab and between the negative electrode core exposed portion and the negative electrode tab, but resistance welding or ultrasonic welding is also used. Then, the electrical resistance between each core body exposed portion and the electrode tab can be reduced, and the manufacturing cost can be reduced.
  • the pressure contact between the positive electrode core exposed portion and the positive electrode tab and the pressure contact between the negative electrode core exposed portion and the negative electrode tab are obtained by an eyelet pressure bonding method. It is preferable that it was performed by.
  • the eyelet pressure bonding method can be used. Since this method can simply and reliably connect the core and the tab, the manufacturing cost can be reduced.
  • welding or pressure welding between the positive electrode core exposed portion and the positive electrode tab and welding or pressure welding between the negative electrode core exposed portion and the negative electrode tab are: These are preferably performed at a plurality of locations.
  • the outer package is a metal rectangular outer package, and one of the positive electrode tab and the negative electrode tab closes an opening of the metal rectangular outer package. It is preferable that the metal sealing plate is electrically connected directly, and the other is electrically connected to a terminal portion attached to the sealing plate in an insulated state.
  • an exterior body made of an aluminum laminate film can also be used.
  • the exterior body is a metal square exterior body such as aluminum or aluminum alloy, iron whose outer surface is plated with nickel, etc., and one of the positive electrode tab and the negative electrode tab has an opening of the metal square exterior body. If the metal sealing plate that is to be closed is electrically connected directly, and the other is electrically connected to a terminal portion that is attached to the sealing plate in an insulated state, the mechanical strength of the battery is high.
  • the leakage of the non-aqueous electrolyte can be reduced, and the dimensional accuracy is improved.
  • the influence of the magnetic field from the inside of the battery on the outside can be further reduced by selecting the materials for the metal rectangular outer casing and the sealing plate.
  • the tabs on both electrodes do not overlap (do not face each other).
  • the tabs of both poles can be arranged so as not to face each other.
  • FIG. 2A is a development view showing a state in which the positive electrode plate and the negative electrode plate of the embodiment are overlapped
  • FIG. 2B is a front view of the wound electrode body of the embodiment
  • FIG. 3A is a development view in which the positive electrode plate and the negative electrode plate of the comparative example are overlapped
  • FIG. 3B is a front view of the wound electrode body of the comparative example.
  • FIG. 4A is a schematic diagram of the current flow of the positive electrode plate and the negative electrode plate of the example
  • FIG. 4B is a schematic diagram of the current flow of the positive electrode plate and the negative electrode plate of the comparative example.
  • FIG. 6A is an explanatory diagram of a magnetic field generation state when the positive electrode tab and the negative electrode tab are formed at both end sides
  • FIG. 6B is the same end portion side.
  • It is a plane schematic diagram which shows the measurement location of a magnetic field common to an Example and a comparative example.
  • FIG. 1 is a perspective view which shows the connection condition of the flat wound electrode body and sealing plate which are common in an Example and a comparative example.
  • the flat wound electrode body 10 of this non-aqueous electrolyte secondary battery has, for example, a positive electrode plate disposed on the outer peripheral side and a negative electrode plate disposed on the inner peripheral side, and is flattened via separators (both not shown). The end of the winding is insulated by the insulating tape 11.
  • the flat wound electrode body 10 has a positive electrode tab 12 connected to a positive electrode core exposed portion and a negative electrode tab 13 connected to a negative electrode core exposed portion.
  • the flat wound electrode body 10 is provided with insulating spacers 14 and 15 on the upper surface and the lower surface, respectively, and the positive electrode tab 12 is bent through the outer peripheral side of the upper insulating spacer 14 to be the inner surface of the sealing plate 16.
  • the negative electrode tab 13 is resistance-welded to a negative electrode terminal 18 formed on the sealing plate 16 through a slit 17 formed in the upper insulating spacer 14.
  • the flat wound electrode body 10 is not shown in the drawing, it is inserted into a substantially flat conductive box-type battery outer casing whose one end surface in the longitudinal direction is open and whose peripheral surface is closed, The opening is sealed by the sealing plate 16 and sealed by laser welding between the opening edge of the battery outer can and the sealing plate 16, and then a predetermined amount of nonaqueous electrolyte is injected from the electrolyte injection hole 19.
  • the electrolyte solution injection hole 19 is sealed.
  • FIGS. 2 and 3 are development views in which the positive electrode plate and the negative electrode plate of the example are overlapped, and FIG. 2B is a plan view of the wound electrode body 10A of the example.
  • FIG. 3A is a development view in which the positive electrode plate and the negative electrode plate of the comparative example are overlapped, and FIG. 3B is a plan view of the wound electrode body 10B of the comparative example. 2A and 3A, the separator is not shown.
  • the difference in configuration between the positive electrode plate and negative electrode plate of the example and the positive electrode plate and negative electrode plate of the comparative example is the shape of the positive electrode core exposed portion and the negative electrode core exposed portion, and the welding of the positive electrode tab and the negative electrode tab. Since it is in a state, hereinafter, the same reference numerals are given to the common components to be described.
  • Lithium cobaltate as a positive electrode active material, acetylene black as a carbon-based conductive agent, and PVDF (polyvinylidene fluoride) are mixed at a mass ratio of 95: 2.5: 2.5 to obtain NMP (N-methylpyrrolidone).
  • NMP N-methylpyrrolidone
  • a positive electrode mixture slurry was applied to both surfaces of a 13 ⁇ m thick aluminum positive electrode core 21 by a doctor blade method and dried to form positive electrode active material layers 22 on both surfaces of the positive electrode core 21. Then, it compressed using the compression roller and produced the positive electrode plate whose short side length is 43 mm.
  • non-aqueous electrolyte a non-aqueous electrolyte obtained by dissolving LiPF 6 in a mixed solvent having a volume mixing ratio of ethylene carbonate, ethyl methyl carbonate and diethyl carbonate of 40:30:30 so as to have a concentration of 1 mol / L was used. .
  • the positive electrode plate 20 is provided with a positive electrode core exposed portion that does not have the positive electrode active material layer 22 on both surfaces of the positive electrode core 21 at a certain distance from the winding end portion of the positive electrode core 21.
  • the lengths of the positive electrode core exposed part 21a of the example and the positive electrode core exposed part 21b of the comparative example are both 35 mm, and the width of the positive electrode core exposed part 21a of the example is 1 of the width of the positive electrode plate 20.
  • the width of the positive electrode core exposed portion 21b of the comparative example is the same as the width of the positive electrode plate 20, whereas the width is 1/2 mm or less, specifically 5 mm.
  • the negative electrode plate 24 is provided with a negative electrode core exposed portion that does not have the negative electrode active material layer 26 on both surfaces of the negative electrode core 25 by a certain distance from the winding end of the negative electrode core 25.
  • the length of the negative electrode core exposed portion 25a in the example and the length of the negative electrode core exposed portion 25b in the comparative example are both 15 mm, and the width of the negative electrode core exposed portion 25a in the example is 1/2 of the width of the negative electrode plate 24.
  • the thickness is specifically reduced to 6 mm, and the width of the negative electrode core exposed portion 25 b of the comparative example is made the same as the width of the negative electrode plate 24. Therefore, in the wound electrode body 10A of the example, as shown in FIG.
  • the wound portion of the positive electrode core exposed portion 21a is formed only on the uppermost outermost side. Further, as shown in FIG. 3B, the wound electrode body 10B of the comparative example is formed with the wound portion of the positive electrode core exposed portion 21b over the entire width on the outermost peripheral side, and the positive electrode core exposed portion 21b is greatly exposed. To come.
  • the positive electrode core exposed portion 21b and the negative electrode core exposed portion 25b of the comparative example have the same width as the positive electrode plate 20 and the negative electrode plate 24, that is, the positive electrode core 21 and the negative electrode core 25, respectively. Both have the same width over the entire length.
  • the positive electrode tab 12a is made of aluminum metal having a thickness of 0.1 mm, a width of 3 mm, and a length of 50 mm
  • the negative electrode tab 13b is made of nickel metal having a thickness of 0.1 mm, a width of 3 mm, and a length of 50 mm.
  • spot welding is performed by spot welding at 8 locations at intervals of 5 mm at intervals of 4 mm from the top and 3 mm from the bottom. did.
  • the positive electrode tab 12a is made of aluminum metal.
  • the negative electrode tab 13b is made of nickel metal with a thickness of 0.1 mm, a width of 3 mm, and a length of 10 mm. Since the contact length with the negative electrode tab 13a is short, the positive electrode tab 12a thru
  • or the negative electrode tab 13a and the welding point of the positive electrode core body exposed part 21a and the negative electrode core body exposed part 25a may be one each, but the positive electrode core body exposed part 21a and the negative electrode core body Since the exposed portion 25a is weak in mechanical strength, the positive electrode tab 12a or the negative electrode tab 13a is easily rotated when the number of welded portions is one, and the position of the positive electrode tab 12a or the negative electrode tab 13a is likely to change during battery assembly. . Therefore, it is desirable that the number of welding points between the positive electrode tab 12a or the negative electrode tab 13a, the positive electrode core exposed portion 21a, and the negative electrode core exposed portion 25a in the embodiment be two or more.
  • the positive electrode plate 20 and the negative electrode plate 24 produced as described above are wound in a state where the outer peripheral side is the positive electrode plate 20 and insulated from each other with a separator made of a polyethylene microporous film interposed therebetween, The end portion of the winding was fixed with the insulating tape 11 and crushed to produce the flat wound electrode body 10A of the example and the wound electrode body 10B of the comparative example.
  • the positive electrode tabs 12a and 12b and the negative electrode tabs 13a and 13b were protruded from the upper portions of the respective flat wound electrode bodies 10A and 10B.
  • the schematic configurations of the flat wound electrode bodies 10A and 10B are as shown in FIGS. 2B and 3B, respectively.
  • non-aqueous electrolyte secondary battery the flat wound electrode bodies 10A and 10B manufactured in this way are not shown in the figure, but are substantially flat conductive with one end surface in the longitudinal direction opened and the peripheral surface closed. It is inserted into the battery outer can, the opening is sealed with the sealing plate 16, and sealed between the opening edge of the battery outer can and the sealing plate 16 by laser welding.
  • Non-aqueous electrolyte secondary batteries corresponding to Examples and Comparative Examples were manufactured by injecting a fixed amount of non-aqueous electrolyte and sealing the electrolyte injection hole 19.
  • the dimensions of the obtained nonaqueous electrolyte secondary battery are thickness 5.2 mm ⁇ width 34 mm ⁇ height 50 mm, and the design capacity is 1150 mAh.
  • the prepared battery was charged under the same conditions as described above, and one end of each lead wire was connected to the battery surface side of the negative electrode terminal 18 and the sealing plate 16 (positive electrode). In order to eliminate the influence of the magnetic field due to the current flowing in the lead wires, the lead wires were twisted together. Then, the other end of the lead wire was connected to the output terminal of the power supply, and the magnetic field around the battery was measured while applying a discharge load having a pulse waveform of GSM specifications to the battery using the power supply.
  • the pulse waveform shape of the GSM specification is that the frequency is 217 Hz, the current 2A is 0.6 milliseconds, and 0.1 A is 1.4 milliseconds.
  • the side where the area of the battery is the maximum is left in the vertical direction, and the plane is 1 cm above the side of the battery.
  • the magnitude of the magnetic field was obtained at 8 locations shown in FIG. The results are shown in Table 1.
  • FIG. 7 is a plan view schematically showing a state in which the side surface having the largest battery area is left in a vertical direction.
  • the upper side of the flat wound electrode body 10 inside the battery (the sealing plate 16 is shown).
  • the height direction of the battery is defined as the x-axis
  • the width direction is defined as the y-axis
  • the thickness direction is defined as the z-axis (not shown).
  • Table 1 also shows the magnetic field strength (unit: xyz) in the xyz directions with respect to the strength of the magnetic field at 8 locations shown in FIG. 7 (however, located on a plane 1 cm away from the battery surface in the z-axis direction).
  • dB ⁇ A / m the magnetic field strength in the x-axis direction at the position of the circled numeral 2 in FIG.
  • the positive electrode core exposed portion 21a to the negative electrode core exposed portion 25a are not present in the same part as the width of the positive electrode plate 20 to the negative electrode plate 24.
  • the positive electrode active material layer 22 or the negative electrode active material layer 26 is formed to have a constant narrow width immediately from the formation portion. Therefore, in the positive electrode plate 20 and the negative electrode plate 24 of the embodiment, even if the welding points between the positive electrode tab 12a or the negative electrode tab 13a and the positive electrode core exposed portion 21a or the negative electrode core exposed portion 25a are separated from each other.
  • the direction of the current flowing through the positive electrode core exposed portion 21a or the negative electrode core exposed portion 25a is parallel to each other in the opposite direction as shown in FIG. 4A. Since the magnetic fields to be canceled out, the magnitude of the magnetic field leaking to the outside is reduced.
  • the positive electrode core exposed portion 21b to the negative electrode core exposed portion 25b are all equal to the width of the formed portion of the positive electrode plate 20 to the negative electrode plate 24. It has become. Further, in the nonaqueous electrolyte secondary battery, the negative electrode plate 24 has a larger area than the positive electrode plate 20 in order to suppress generation of lithium dendrite on the negative electrode plate.
  • the current flowing from each active material layer forming region side should flow to the welding point of each electrode tab at the shortest distance.
  • a component that flows from the lower negative electrode active material layer 26 to the upper side of the battery (the side where the negative electrode tab 13b is formed) is generated.
  • the magnetic field formed by the current flowing upward from the lower negative electrode active material layer 26 on the negative electrode plate side 24 is not canceled by the magnetic field formed by the current flowing through the positive electrode plate 20, and therefore leaks to the outside.
  • the magnetic field is not sufficiently small, and there is a high possibility that the hearing aid will be adversely affected.
  • the positive electrode core exposed portion 21a and the negative electrode core exposed portion 25a are formed on the upper side of the battery (the protruding side of the positive electrode tab 12a and the negative electrode tab 13a).
  • the present invention can be carried out even if it is not on the upper side of the battery.
  • the magnetic field generated becomes smaller as the positive electrode core exposed portion 21a and the negative electrode core exposed portion 25a are formed closer to the center in the width direction of the wound electrode body. There was a trend. Therefore, it is more preferable to form the positive electrode core exposed portion 21a and the negative electrode core exposed portion 25a at the central portion in the winding axis direction of the wound electrode body.
  • a magnetic field due to the current flowing in the battery is less likely to occur than the non-aqueous electrolyte secondary battery of the comparative example corresponding to the conventional example.
  • An adverse effect on a user such as a hearing aid is suppressed.
  • the nonaqueous electrolyte secondary battery in which the positive electrode core exposed portion and the negative electrode core exposed portion are provided on the winding end side of the wound electrode body and the positive electrode tab and the negative electrode tab are attached is shown. Since the present invention is effective when the current flowing in the positive electrode plate and the current flowing in the negative electrode plate flow in opposite directions, the winding start side and the winding end side of the wound electrode body If either one of the positive electrode tab and the negative electrode tab is provided on both of them, and the positive electrode tab and the negative electrode tab are led out in the same direction with respect to the winding axis direction of the wound electrode body, the positive electrode tab Even if the negative electrode tab is provided on the winding start side or the winding end side of the wound electrode body, the present invention can be implemented.

Abstract

The purpose of the present invention is to provide a non-aqueous electrolyte secondary cell configured in such a manner that the generation of a magnetic field due to the flow of current during use is reduced, and the effect of noise on a hearing aid etc. due to the magnetic field is reduced. This non-aqueous electrolyte secondary cell has: a positive electrode plate (20) having a positive electrode core exposure section (21a), which has a width of less than 1/2 of the width of the positive electrode plate (20), formed on the side where the winding of the positive electrode plate (20) starts or ends, and a positive electrode tab (12a) welded or cold welded to the positive electrode core exposure section (21a); and a negative electrode plate (24) having a negative electrode core exposure section (25a), which has a width of less than 1/2 of the width of the negative electrode plate (24), formed on the same side as the positive electrode core exposure section (21a), and a negative electrode tab (13a) welded or cold welded to the negative electrode exposure section (25a).

Description

非水電解質二次電池Nonaqueous electrolyte secondary battery
　本発明は、非水電解質二次電池に関し、詳しくは、使用時の電流の流れによる磁界の発生が小さく、補聴器等に対して与える磁界によるノイズの影響が小さくなるようにした非水電解質二次電池に関する。 The present invention relates to a non-aqueous electrolyte secondary battery, and more specifically, a non-aqueous electrolyte secondary battery in which the generation of a magnetic field due to a current flow during use is small and the influence of noise caused by the magnetic field on a hearing aid or the like is small. It relates to batteries.
　今日の携帯電話機、携帯型パーソナルコンピューター、携帯型音楽プレイヤー等の携帯型電子機器の駆動電源として、更には、ハイブリッド電気自動車（ＨＥＶ）や電気自動車（ＥＶ）用の電源として、高エネルギー密度を有し、高容量であるリチウムイオン二次電池に代表される非水電解質二次電池が広く利用されている。 It has high energy density as a driving power source for portable electronic devices such as today's mobile phones, portable personal computers, portable music players, and also as a power source for hybrid electric vehicles (HEV) and electric vehicles (EV). However, non-aqueous electrolyte secondary batteries represented by high-capacity lithium ion secondary batteries are widely used.
　これらの非水電解質二次電池は、一般に、細長いシート状のアルミニウム箔等からなる正極芯体の両面にリチウムイオンを吸蔵・放出する正極活物質を含む正極合剤を塗布した正極と、細長いシート状の銅箔等からなる負極芯体の両面にリチウムイオンを吸蔵放出する負極活物質を含む負極合剤を塗布した負極とを有し、これらの正極及び負極の間に微多孔性ポリエチレンフィルム等からなるセパレータを配置し、正極及び負極をセパレータにより互いに絶縁した状態で円柱状又は楕円形状に巻回して巻回電極体を形成し、角形電池の場合は更に巻回電極体を押し潰して偏平な巻回電極体を形成した後、正極及び負極の各所定部分にそれぞれ正極タブ及び負極タブを接続し、その外側を外装で被覆することにより製造されている。 These non-aqueous electrolyte secondary batteries generally include a positive electrode in which a positive electrode mixture containing a positive electrode active material that absorbs and releases lithium ions is applied to both surfaces of a positive electrode core made of an elongated sheet-like aluminum foil, and an elongated sheet. A negative electrode in which a negative electrode mixture containing a negative electrode active material that occludes and releases lithium ions is applied to both surfaces of a negative electrode core made of, for example, a copper foil, and a microporous polyethylene film or the like between the positive electrode and the negative electrode The separator is made of and wound into a cylindrical or elliptical shape with the positive electrode and the negative electrode insulated from each other by the separator to form a wound electrode body. In the case of a rectangular battery, the wound electrode body is further crushed and flattened. After a simple wound electrode body is formed, a positive electrode tab and a negative electrode tab are connected to predetermined portions of the positive electrode and the negative electrode, respectively, and the outside is covered with an exterior.
　なお、従来の非水電解質二次電池においては、正極タブないし負極タブは、正極芯体ないし負極芯体の露出部にそれぞれ超音波溶接、抵抗溶接ないし圧接（圧着を含む）することによって電気的に接続されている。このような従来の正極タブないし負極タブを正極芯体ないし負極芯体の露出部に電気的に接続するための構成の一例を、図５を用いて説明する。なお、図５は、下記特許文献１に示されている正極タブないし負極タブの構成を示す平面図である。 In the conventional nonaqueous electrolyte secondary battery, the positive electrode tab or the negative electrode tab is electrically connected by ultrasonic welding, resistance welding or pressure welding (including pressure bonding) to the exposed portion of the positive electrode core or negative electrode core, respectively. It is connected to the. An example of a configuration for electrically connecting such a conventional positive electrode tab or negative electrode tab to the exposed portion of the positive electrode core or negative electrode core will be described with reference to FIG. FIG. 5 is a plan view showing a configuration of a positive electrode tab or a negative electrode tab disclosed in Patent Document 1 below.
　下記特許文献１に示されている電極５０は、芯体５１上に電極材料層５２が形成されているとともに、電極材料層未形成部分５３に金属リードからなる電極タブ５４が抵抗溶接された構成を備えており、この電極タブ５４の表面に平均径が０．５μｍ以上１０．０μｍ以下の凹凸部を形成することにより、芯体５１と電極タブ５４との間の接触抵抗を増大化させて良好な溶接スポット点５５が形成されるようにし、芯体５１と電極タブ５４との間の溶接強度の低下及び位置ずれを抑制することができるようにしたものである。上記特許文献１に示されている電極によれば芯体と電極タブとの間の抵抗溶接をより強固にかつ確実に行うことができるという効果を奏する。 An electrode 50 shown in Patent Document 1 below has a structure in which an electrode material layer 52 is formed on a core body 51 and an electrode tab 54 made of a metal lead is resistance-welded to an electrode material layer non-formed portion 53. And the contact resistance between the core 51 and the electrode tab 54 is increased by forming an uneven portion having an average diameter of 0.5 μm or more and 10.0 μm or less on the surface of the electrode tab 54. A good welding spot point 55 is formed, and a decrease in welding strength and displacement between the core 51 and the electrode tab 54 can be suppressed. According to the electrode disclosed in Patent Document 1, there is an effect that resistance welding between the core and the electrode tab can be performed more firmly and reliably.
特開２００２－００８６２３号公報JP 2002-008623 A 特開２００３－１２３７３２号公報JP 2003-123732 A 特開２００４－２５３３８１号公報JP 2004-253381 A
　一方、携帯電子機器は、使用時に電池に流れる電流によって磁界が発生するが、これらの磁界がノイズとなって特に補聴器の使用者に悪影響を及ぼすことがある。補聴器は、外部の音声をマイクで捉えて増幅する機能を備えるほか、電磁コイルによって電話機のスピーカ部分から発生する磁束を電磁ピックアップ（「テレホンピックアップ」とも称される。）で捉えて増幅する機能をも備えているため、特に外部からの磁界ノイズの影響を受けやすい。補聴器がこのような電磁ピックアップを使用する理由は、電話機のスピーカから出力された音声を補聴器のマイクで拾って増幅すると、周囲の雑音もマイクで拾ってしまうために、音声の明瞭度が低下するためである。 On the other hand, in mobile electronic devices, magnetic fields are generated by the current that flows through the battery when in use, but these magnetic fields may become noise, which may adversely affect hearing aid users. The hearing aid has a function of capturing and amplifying external sound with a microphone, and a function of capturing and amplifying magnetic flux generated from the speaker portion of the telephone by an electromagnetic coil with an electromagnetic pickup (also referred to as “telephone pickup”). In particular, it is easily affected by external magnetic field noise. The reason why the hearing aid uses such an electromagnetic pickup is that when the sound output from the speaker of the telephone is picked up and amplified by the microphone of the hearing aid, ambient noise is picked up by the microphone, so that the clarity of the sound is lowered. Because.
　特に携帯電話機は補聴器に近接した位置で使用されるため、携帯電話機から発生する磁界は補聴器に対して悪影響を与えやすい。そのため、携帯電話機の電源である非水電解質二次電池においても、この非水電解質二次電池に流れる電流に起因する磁界の発生を抑制することが要望されている。 Especially, since the mobile phone is used at a position close to the hearing aid, the magnetic field generated from the mobile phone tends to adversely affect the hearing aid. For this reason, even in a non-aqueous electrolyte secondary battery that is a power source of a mobile phone, it is desired to suppress the generation of a magnetic field due to the current flowing through the non-aqueous electrolyte secondary battery.
　なお、電池では、一般に正極を流れる電流と負極を流れる電流を逆向きにすれば、それぞれの電流による磁界が互いに打ち消し合うので、磁界低減が可能であると考えられている。電池は、正極極板及び負極極板のそれぞれで生じる化学反応によって得られる電流を正極タブないし負極タブで取り出すことによって集電される。そのため、正極極板及び負極極板の活物質形成領域中を流れる電流に起因する磁界は、正極タブないし負極タブの位置を共にそれぞれの極板の巻き始め側或いは巻き終わり側とし、しかも互いに重複ないし近接した位置に配置すれば、それぞれの電流の流れる方向は逆方向で平行となるので、低減することができる。ただし、正極タブ及び負極タブの位置を互いに重複する位置に配置すると、各タブの電気的絶縁及び取付が困難となるので、直ちには採用し難い。 In addition, in a battery, it is generally considered that if the current flowing through the positive electrode and the current flowing through the negative electrode are reversed, the magnetic fields due to the respective currents cancel each other, so that the magnetic field can be reduced. The battery is collected by taking out the current obtained by the chemical reaction generated in each of the positive electrode plate and the negative electrode plate with the positive electrode tab or the negative electrode tab. For this reason, the magnetic field caused by the current flowing in the active material formation region of the positive electrode plate and the negative electrode plate has the positions of the positive electrode tab or the negative electrode tab both on the winding start side or the winding end side of each electrode plate and overlap each other. Or if it arrange | positions in the position which adjoined, since the direction through which each electric current flows becomes parallel in the reverse direction, it can reduce. However, if the positions of the positive electrode tab and the negative electrode tab are arranged at positions overlapping each other, it is difficult to electrically insulate and attach each tab, so that it is difficult to adopt immediately.
　例えば、正極極板は巻終り側に正極タブが取り付けられており、負極極板は巻き始め側に負極タブが取り付けられている場合、放電時には、図６Ａに示すように、正極側では左から右側に順次電流値が大きくなる電流が流れ、負極側では左側から右側へ順次電流値が小さくなる電流が流れる。そのため、正極極板の正極活物質形成領域中を流れる電流は負極極板の負極活物質形成領域中を流れる電流と平行かつ同方向になるので、電池を流れる電流に起因する磁界は大きくなる。 For example, when the positive electrode plate has a positive electrode tab attached to the winding end side and the negative electrode plate has a negative electrode tab attached to the winding start side, during discharge, as shown in FIG. A current whose current value sequentially increases on the right side flows, and on the negative electrode side, a current whose current value decreases sequentially from the left side to the right side. For this reason, the current flowing in the positive electrode active material forming region of the positive electrode plate is parallel and in the same direction as the current flowing in the negative electrode active material forming region of the negative electrode plate, so that the magnetic field caused by the current flowing through the battery is increased.
　それに対し、図６Ｂに示すように、正極極板は巻始め側に正極タブが取り付けられており、負極も巻き始め側に負極タブが取り付けられている場合、正極側では右から左側に順次電流値が大きくなる電流が流れ、負極側では左側から右側へ順次電流値が小さくなる電流が流れる。そのため、正極極板の正極活物質形成領域を流れる電流は負極極板の負極活物質形成領域を流れる電流と平行にかつ逆方向になるので、電池を流れる電流に起因する磁界は打ち消しあう。 On the other hand, as shown in FIG. 6B, when the positive electrode plate has a positive electrode tab attached to the winding start side and the negative electrode also has a negative electrode tab attached to the winding start side, the current is sequentially increased from right to left on the positive electrode side. A current with a larger value flows, and a current with a smaller current value flows from the left side to the right side on the negative electrode side. For this reason, the current flowing through the positive electrode active material forming region of the positive electrode plate is parallel and opposite to the current flowing through the negative electrode active material forming region of the negative electrode plate, so that the magnetic fields caused by the current flowing through the battery cancel each other.
　しかしながら、正極タブないし負極タブの溶接（「圧接」も含む。以下、同じ。）は、例えば図５の記載からも明らかなように、スポット的に複数箇所において行われているものであり、全面に亘って均質に行われているものではない。そのため、溶接箇所の近傍では、芯体部を流れる電流は、それぞれの溶接箇所で複雑な方向に流れるため、様々な磁界が生成している。また、活物質形成領域の終端とタブ溶接位置が近くなると、さらに電流の流れが複雑になりやすくなり、磁界が発生しやすくなる要因となる。したがって、非水電解質二次電池に流れる電流に起因する磁界の発生を抑制するためには、正極タブないし負極タブの取り付け構造について更に改良する余地が存在している。 However, welding of the positive electrode tab or the negative electrode tab (including “pressure welding”, the same applies hereinafter) is performed at a plurality of spots in a spot manner as is apparent from the description of FIG. It is not performed uniformly throughout. Therefore, in the vicinity of the welding location, the current flowing through the core body portion flows in a complicated direction at each welding location, so that various magnetic fields are generated. In addition, when the end of the active material formation region and the tab welding position are close, the current flow becomes more complicated and becomes a factor that a magnetic field is easily generated. Therefore, there is room for further improvement in the attachment structure of the positive electrode tab or the negative electrode tab in order to suppress the generation of a magnetic field due to the current flowing in the nonaqueous electrolyte secondary battery.
　発明者等は、上述のような問題点を解決すべく種々検討を重ねた結果、正極タブないし負極タブの溶接位置を共に極板の巻き始め側或いは巻き終わり側とすると共に、正極タブないし負極タブを形成するそれぞれの芯体露出部の幅を小さくし、この芯体露出部に正極タブないし負極タブをそれぞれ溶接することにより、電池に流れる電流に起因する磁界の発生を極めて小さくすることができることを見出し、本発明を完成するに至ったのである。 The inventors have made various studies to solve the above-mentioned problems, and as a result, the welding positions of the positive electrode tab or the negative electrode tab are both set to the winding start side or the winding end side of the electrode plate, and the positive electrode tab or the negative electrode. By reducing the width of each core exposed portion forming the tab and welding the positive electrode tab or the negative electrode tab to the core exposed portion, the generation of the magnetic field due to the current flowing in the battery can be extremely reduced. The present inventors have found out what can be done and have completed the present invention.
　なお、上記特許文献２には、図８に示したように、リチウムイオンポリマ電池の集電体（芯体）６１上に活物質層６２が形成されている正極極板ないし負極極板６０において、電極リード（集電タブ）６３は、芯体６１の活物質層非形成部分６４の切り込みが入れられて折り曲げられ、この折り曲げられた部分からなるようにした例が示されている。 In Patent Document 2, as shown in FIG. 8, in a positive electrode plate or negative electrode plate 60 in which an active material layer 62 is formed on a current collector (core body) 61 of a lithium ion polymer battery. The electrode lead (current collecting tab) 63 is an example in which an active material layer non-formation portion 64 of the core body 61 is cut and bent, and the electrode lead (current collection tab) 63 is formed of the bent portion.
　また、上記特許文献３には、図９に示したように、正極極板７１及び負極極板７２がそれぞれセパレータ７３を介して互いに絶縁された状態で巻回された電極体（図示省略）を備えており、正極極板７１の正極活物質層７４が形成されていない正極芯体露出部７５には正極タブ７６が溶接されており、負極極板７３の負極活物質層７７が形成されていない負極芯体露出部７８には、負極芯体露出部７８の終端部の一部を負極芯体露出部７８の幅方向に１／２以上切開し、折り曲げることによって負極タブ７９を形成した例が示されている。なお、参照符号８０ａ～８０ｄは絶縁テープである。 Further, in Patent Document 3, as shown in FIG. 9, an electrode body (not shown) in which a positive electrode plate 71 and a negative electrode plate 72 are wound in a state of being insulated from each other via a separator 73 is provided. A positive electrode tab 76 is welded to the positive electrode core exposed portion 75 of the positive electrode plate 71 where the positive electrode active material layer 74 is not formed, and a negative electrode active material layer 77 of the negative electrode plate 73 is formed. An example in which the negative electrode core exposed portion 78 has a negative electrode tab 79 formed by cutting and bending a part of the terminal end of the negative electrode core exposed portion 78 in the width direction of the negative electrode core exposed portion 78 more than 1/2. It is shown. Reference numerals 80a to 80d are insulating tapes.
　しかしながら、上記特許文献２及び３には、電池に流れる電流に起因する磁界の発生については何も考慮されておらず、しかも、活物質層形成領域の幅と同じ幅の正極芯体露出部ないし負極芯体露出部が形成されており、この活物質層形成領域の幅と同じ幅の正極芯体露出部ないし負極芯体露出部の存在に起因する磁界の発生の問題点については何も示唆されていない。 However, the above Patent Documents 2 and 3 do not consider anything about the generation of a magnetic field due to the current flowing in the battery, and the positive electrode core exposed portion or the width of the active material layer forming region is the same as the width of the active material layer forming region. A negative electrode core exposed portion is formed, and there is no suggestion about the problem of generation of a magnetic field due to the presence of the positive electrode core exposed portion or the negative electrode core exposed portion having the same width as the active material layer forming region. It has not been.
　すなわち、本発明は、使用時の電流の流れによる磁界の発生が小さく、補聴器等に対して磁界によるノイズの影響が小さくなるようにした非水電解質二次電池を提供することを目的とする。 That is, an object of the present invention is to provide a non-aqueous electrolyte secondary battery in which generation of a magnetic field due to a current flow during use is small and the influence of noise due to the magnetic field on a hearing aid or the like is reduced.
　上記目的を達成するため、本発明の非水電解質二次電池は、正極合剤層が正極芯体の両面に塗布された正極極板と、負極活物質層が負極芯体の両面に塗布された負極極板とが、それぞれセパレータを挟んで巻回された偏平状の巻回電極体と、前記偏平状の巻回電極体を収納する外装体と、前記外装体内に注入された非水電解液と、を備える非水電解質二次電池において、前記正極極板は、前記正極極板の巻き始め側又は巻き終わり側に前記正極極板の幅の１／２よりも短い幅の正極芯体露出部が形成され、前記正極芯体露出部には正極タブが溶接または圧接されており、前記負極極板は、前記正極芯体露出部と同じ側に、前記負極極板の幅の１／２よりも短い幅の負極芯体露出部が形成されて、前記正極芯体露出部及び前記負極芯体露出部が前記セパレータを介して対向しており、前記負極芯体露出部には負極タブが溶接または圧接されており、前記正極タブ及び前記負極タブは、前記巻回電極体の巻回軸方向に対して同じ方向に導出されていることを特徴とする。 In order to achieve the above object, the nonaqueous electrolyte secondary battery of the present invention includes a positive electrode plate in which a positive electrode mixture layer is applied to both surfaces of a positive electrode core, and a negative electrode active material layer applied to both surfaces of the negative electrode core. A flat wound electrode body wound with a separator sandwiched between each of the negative electrode plates, an exterior body housing the flat wound electrode body, and nonaqueous electrolysis injected into the exterior body A positive electrode core having a width shorter than ½ of the width of the positive electrode plate on the winding start side or the winding end side of the positive electrode plate. An exposed portion is formed, and a positive electrode tab is welded or pressed to the exposed portion of the positive electrode core, and the negative electrode plate is disposed on the same side as the exposed portion of the positive electrode core on the same side as the 1 / width of the negative electrode plate. A negative electrode core exposed portion having a width shorter than 2 is formed, and the positive electrode core exposed portion and the negative electrode core exposed portion It faces through the separator, and a negative electrode tab is welded or pressed to the negative electrode core exposed portion, and the positive electrode tab and the negative electrode tab are in a winding axis direction of the wound electrode body. It is derived in the same direction.
　正極タブ及び負極タブの溶接点または圧接点は、周知の抵抗溶接装置、超音波溶接装置、レーザ溶接装置等の溶接手段または圧接手段の構成からして、正極タブないし負極タブが正極芯体露出部ないし負極芯体露出部と接している面の全体にわたって均一に形成されることはなく、部分的に形成される。また、非水電解質二次電池では、負極極板でのリチウムデンドライト発生を抑制するために、正極極板よりも負極極板の方が面積が大きくなるように作製される。 The welding point or the pressure contact of the positive electrode tab and the negative electrode tab is composed of welding means or pressure welding means such as a known resistance welding apparatus, ultrasonic welding apparatus, laser welding apparatus, etc., and the positive electrode tab or the negative electrode tab is exposed to the positive electrode core. It is not formed uniformly over the entire surface in contact with the portion or the negative electrode core exposed portion, but is formed partially. In addition, the nonaqueous electrolyte secondary battery is manufactured such that the area of the negative electrode plate is larger than that of the positive electrode plate in order to suppress generation of lithium dendrite in the negative electrode plate.
　そのため、従来の正極極板及び負極極板では、それぞれの活物質層形成領域側から流れる電流は、それぞれの電極タブの溶接点または圧接点へ最短距離で流れようとするが、少なくとも負極極板側では下側負極活物質層側から電池の上側（負極タブが形成されている側）に流れる成分が生じる。そしてこの成分は、負極活物質層形成領域終端と負極タブとの距離が短い場合は顕著になる傾向にある。この負極極板側における下側の負極活物質層側から上側に流れる電流によって形成される磁界は、正極極板に流れる電流によって形成される磁界によって打ち消されないので、外部に漏出して補聴器等に悪影響を与えることとなる。 Therefore, in the conventional positive electrode plate and negative electrode plate, the current flowing from each active material layer forming region side tends to flow at the shortest distance to the welding point or pressure contact of each electrode tab, but at least the negative electrode plate On the side, a component flows from the lower negative electrode active material layer side to the upper side of the battery (the side where the negative electrode tab is formed). This component tends to become prominent when the distance between the end of the negative electrode active material layer forming region and the negative electrode tab is short. The magnetic field formed by the current flowing upward from the lower negative electrode active material layer side on the negative electrode plate side is not canceled by the magnetic field formed by the current flowing through the positive electrode plate. Will be adversely affected.
　それに対し、本発明の非水電解質二次電池では、正極極板は、正極極板の巻き始め側又は巻き終わり側に正極極板の幅の１／２よりも短い幅の正極芯体露出部が形成され、この正極芯体露出部には正極タブが溶接または圧接されており、また、負極極板は、正極芯体露出部と同じ側に、負極極板の幅の１／２よりも短い幅の負極芯体露出部が前記セパレータを介して前記正極芯体露出部と対向するように形成され、この負極芯体露出部には負極タブが溶接または圧接されており、さらに、前記正極タブ及び前記負極タブが前記巻回電極体の巻回軸方向に対して同じ方向に導出されている。そのため、本発明の非水電解質二次電池によれば、正極芯体露出部ないし負極芯体露出を経て正極タブないし負極タブに流れる電流は、共に電池の上側に集中して、それぞれ互いに反対方向に、平行に流れるようになるので、正極極板及び負極極板に流れる電流による磁界は互いに打ち消し合うため、磁界低減が可能となる。 On the other hand, in the nonaqueous electrolyte secondary battery of the present invention, the positive electrode plate has a positive electrode core exposed portion having a width shorter than ½ of the width of the positive electrode plate on the winding start side or winding end side of the positive electrode plate. A positive electrode tab is welded or pressed to the exposed portion of the positive electrode core, and the negative electrode plate is on the same side as the exposed portion of the positive electrode core, and is less than half the width of the negative electrode plate. A negative electrode core exposed portion with a short width is formed so as to face the positive electrode core exposed portion via the separator, and a negative electrode tab is welded or pressed to the negative electrode core exposed portion. The tab and the negative electrode tab are led out in the same direction with respect to the winding axis direction of the wound electrode body. Therefore, according to the nonaqueous electrolyte secondary battery of the present invention, the current flowing through the positive electrode tab or the negative electrode tab through the positive electrode core exposed portion or the negative electrode core exposure is concentrated on the upper side of the battery, and the directions are opposite to each other. In addition, since the current flows in parallel, the magnetic fields caused by the currents flowing through the positive electrode plate and the negative electrode plate cancel each other, so that the magnetic field can be reduced.
　なお、正極芯体露出部の幅ないし負極芯体露出部の幅は、それぞれの極板の幅の１／２以上になると、正極極板及び負極極板の面積の差異に基づいて流れる電流の方向に差異が生じるようになるので、磁界が互いに打ち消し合うことができなくなるので、好ましくない。そのため、本発明の非水電解質二次電池では、従来技術が備えている正極芯体露出部の幅ないし負極芯体露出部の幅が正極極板ないし負極極板の幅と同じ領域を備えていないようにすることが必須である。 When the width of the positive electrode core exposed portion or the width of the negative electrode core exposed portion is ½ or more of the width of each electrode plate, the current flowing based on the difference in area between the positive electrode plate and the negative electrode plate Since a difference occurs in the direction, the magnetic fields cannot cancel each other, which is not preferable. Therefore, in the nonaqueous electrolyte secondary battery of the present invention, the width of the positive electrode core exposed portion or the width of the negative electrode core exposed portion provided in the prior art is the same as the width of the positive electrode plate or the negative electrode plate. It is essential not to.
　また、本発明においては、正極極板中に流れる電流と負極極板中に流れる電流とが反対方向に流れるようになれば効果が奏されるため、正極タブ及び負極タブは、巻回電極体の巻き始め側に設けられていても、巻き終わり側に設けられていても良い。 In the present invention, the positive electrode tab and the negative electrode tab are wound electrode bodies because an effect is obtained if the current flowing in the positive electrode plate and the current flowing in the negative electrode plate flow in opposite directions. It may be provided on the winding start side or on the winding end side.
　また、本発明においては、正極タブ及び負極タブを巻回電極体の巻き終わり側に設ける場合は、短絡防止の観点から、外装体の極性と同じ極性である方の電極の芯体露出部が巻回電極体の最外周に配置されていることが好ましい。 Further, in the present invention, when the positive electrode tab and the negative electrode tab are provided on the winding end side of the wound electrode body, the core body exposed portion of the electrode having the same polarity as the polarity of the exterior body is used from the viewpoint of preventing a short circuit. It is preferable to arrange | position at the outermost periphery of a wound electrode body.
　また、巻回電極体の最外周に配置される方の電極の芯体露出部の長さは、反対極の芯体露出部の長さよりも長くすることが好ましく、更にタブを取り付けた箇所の強度を考慮すると巻回電極体最外周の１周の長さの１／２以上が好ましいが、長過ぎると電池容量が低下する虞があるため、巻回電極体最外周の１周の長さ以下とすることが好ましい。 In addition, the length of the core exposed portion of the electrode disposed on the outermost periphery of the wound electrode body is preferably longer than the length of the core exposed portion of the opposite electrode, and further the portion where the tab is attached. Considering the strength, it is preferably at least 1/2 of the length of the outer circumference of the wound electrode body. However, if the length is too long, the battery capacity may be reduced. The following is preferable.
　また、本発明においては、正極タブ及び負極タブを巻回電極体の巻き始め側に設ける場合は、正極芯体露出部及び負極芯体露出部の長さは、巻回電極体の最内周の１周の長さの１／４～１／２程度とすることが好ましい。短過ぎると芯体露出部の強度が不足する虞があり、長過ぎると電池容量が低下する虞がある。 In the present invention, when the positive electrode tab and the negative electrode tab are provided on the winding start side of the wound electrode body, the lengths of the positive electrode core exposed part and the negative electrode core exposed part are the innermost circumference of the wound electrode body. It is preferable that the length is about 1/4 to 1/2 of the length of one circle. If it is too short, the strength of the core exposed portion may be insufficient, and if it is too long, the battery capacity may be reduced.
　また、短絡防止の観点から、一方の極板の芯体露出部に設けられた電極タブが同一極性である一方の極板と対向するようになされていることが好ましく、このような構成は、予め正極極板及び負極極板のどちらか一方の芯体露出部を他方の芯体露出部よりも長くなるように形成しておき、巻回電極体の製造時に巻き取り開始のタイミングを正極と負極とでずらし、芯体露出部の長い一方の極板を先に巻き始めて、一方の芯体露出部におけるタブ溶接箇所を巻き取った後に、他方の極板を併せて巻き取り始めるようにすることで、容易に達成することができる。 In addition, from the viewpoint of short circuit prevention, it is preferable that the electrode tab provided in the core body exposed portion of one electrode plate is opposed to one electrode plate having the same polarity. The core exposed portion of either the positive electrode plate or the negative electrode plate is formed in advance so as to be longer than the other core exposed portion, and the winding start timing is set as the positive electrode when the wound electrode body is manufactured. Shift it with the negative electrode, start winding one electrode plate with a long core exposed portion first, wind up the tab welded portion in one core exposed portion, and then start winding the other electrode plate together This can be easily achieved.
　なお、本発明の非水電解質二次電池においては、正極極板に使用する正極活物質としては、リチウムイオンを可逆的に吸蔵・放出することが可能なＬｉＭＯ２（但し、ＭはＣｏ、Ｎｉ、Ｍｎの少なくとも１種である）で表されるリチウム遷移金属複合酸化物、すなわち、ＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＮｉｘＣｏ１－ｘＯ２（ｘ＝０．０１～０．９９）、ＬｉＭｎＯ２、ＬｉＭｎ２Ｏ４、ＬｉＮｉｘＭｎｙＣｏｚＯ２（ｘ＋ｙ＋ｚ＝１）、又はＬｉＦｅＰＯ４などを一種単独でもしくは複数種を混合して用いることができる。また、遷移金属を他の元素と置換したり、他の元素を単独または化合物として添加したりすることができる。 In the nonaqueous electrolyte secondary battery of the present invention, as the positive electrode active material used for the positive electrode plate, LiMO 2 capable of reversibly inserting and extracting lithium ions (where M is Co, Ni , At least one of Mn), that is, LiCoO 2 , LiNiO 2 , LiNi x Co 1-x O 2 (x = 0.01 to 0.99), LiMnO 2 , LiMn 2 O 4 , LiNi x Mn y Co z O 2 (x + y + z = 1), LiFePO 4 , or the like can be used singly or in combination. Moreover, a transition metal can be substituted with another element, or another element can be added alone or as a compound.
　また、負極に使用する負極活物質には、リチウムを吸蔵・放出することが可能な炭素質物、珪素質物、金属酸化物からなる群から選択される少なくとも１種以上を用いることができる。黒鉛化の進んだ炭素質物は高容量であるために特に好ましい。 Further, as the negative electrode active material used for the negative electrode, at least one selected from the group consisting of a carbonaceous material, a siliconaceous material and a metal oxide capable of inserting and extracting lithium can be used. A carbonaceous material that has been graphitized is particularly preferable because of its high capacity.
本発明の非水電解質二次電池の非水電解質で用いることができる非水溶媒は、環状炭酸エステル、鎖状炭酸エステル、エステル類、環状エーテル類、鎖状エーテル類、ニトリル類、アミド類等が挙げられる。環状炭酸エステルとしては、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネートなどが挙げられ、これらの水素基の一部又は全部がフッ素化されているものも用いることが可能であり、例えばトリフルオロプロピレンカーボネートやフルオロエチレンカーボネートなどを用いることができる。また、鎖状炭酸エステルとしては、ジメチルカーボネート、ジエチルカーボネートなどの対称鎖状炭酸エステル、エチルメチルカーボネート、メチルプロピルカーボネート、エチルプロピルカーボネート、メチルイソプロピルカーボネートなどの非対称鎖状炭酸エステルを用いることができ、これらの水素の一部又は全部がフッ素化されているものも用いることが可能である。 Nonaqueous solvents that can be used in the nonaqueous electrolyte of the nonaqueous electrolyte secondary battery of the present invention include cyclic carbonates, chain carbonates, esters, cyclic ethers, chain ethers, nitriles, amides, etc. Is mentioned. Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate and the like, and those in which some or all of these hydrogen groups are fluorinated can also be used. For example, trifluoropropylene Carbonate and fluoroethylene carbonate can be used. Further, as the chain carbonate, symmetric chain carbonates such as dimethyl carbonate and diethyl carbonate, asymmetric chain carbonates such as ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, and methyl isopropyl carbonate can be used. Those in which part or all of these hydrogens are fluorinated can also be used.
　有機電解液を構成する電解質は、過塩素酸リチウム（ＬｉＣｌＯ４）、六フッ化リン酸リチウム（ＬｉＰＦ６）、ホウフッ化リチウム（ＬｉＢＦ４）、六フッ化砒酸リチウム（ＬｉＡｓＦ６）、トリフルオロメチルスルホン酸リチウム（ＬｉＣＦ３ＳＯ３）、ビストリフルオロメチルスルホニルイミドリチウム［ＬｉＮ（ＣＦ３ＳＯ２）２］などのリチウム塩が挙げられる。中でもＬｉＰＦ６、ＬｉＢＦ４を用いるのが好ましく、前記有機溶媒に対する溶解量は、０．５～２．０モル／Ｌとするのが好ましい。なお、本発明においては、非水電解質は、溶液状のものだけでなく、ゲル化されているものも使用することができる。 The electrolyte constituting the organic electrolyte is lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), trifluoromethyl. Examples thereof include lithium salts such as lithium sulfonate (LiCF 3 SO 3 ) and lithium bistrifluoromethylsulfonylimide [LiN (CF 3 SO 2 ) 2 ]. Of these, LiPF 6 and LiBF 4 are preferably used, and the amount dissolved in the organic solvent is preferably 0.5 to 2.0 mol / L. In the present invention, the nonaqueous electrolyte can be used not only in a solution state but also in a gelled state.
　また正極芯体露出部及び負極芯体露出部が巻回電極体の幅の中央部に形成されていると、芯体露出部付近の磁界が小さくなる傾向にあるため、好ましい。 Further, it is preferable that the positive electrode core exposed portion and the negative electrode core exposed portion are formed at the center of the width of the wound electrode body because the magnetic field in the vicinity of the core exposed portion tends to be small.
　また、本発明の非水電解質二次電池においては、前記正極芯体露出部と前記正極タブとの間の溶接及び前記負極芯体露出部と前記負極タブとの間の溶接は、抵抗溶接法又は超音波溶接法によって行われたものであることが好ましい。 In the nonaqueous electrolyte secondary battery of the present invention, welding between the positive electrode core exposed portion and the positive electrode tab and welding between the negative electrode core exposed portion and the negative electrode tab are performed by resistance welding. Or it is preferable that it was what was performed by the ultrasonic welding method.
　正極芯体露出部と正極タブとの間の溶接及び負極芯体露出部と負極タブとの間の溶接は、レーザ溶接法も採用することができるが、抵抗溶接法又は超音波溶接法を採用すると、それぞれの芯体露出部と電極タブとの間の電気抵抗を小さくすることができると共に、製造コストを安くすることができるようになる。 Laser welding can be used for welding between the positive electrode core exposed portion and the positive electrode tab and between the negative electrode core exposed portion and the negative electrode tab, but resistance welding or ultrasonic welding is also used. Then, the electrical resistance between each core body exposed portion and the electrode tab can be reduced, and the manufacturing cost can be reduced.
　また、本発明の非水電解質二次電池においては、前記正極芯体露出部と前記正極タブとの間の圧接及び前記負極芯体露出部と前記負極タブとの間の圧接は、ハトメ圧着法によって行われたものであることが好ましい。 Further, in the nonaqueous electrolyte secondary battery of the present invention, the pressure contact between the positive electrode core exposed portion and the positive electrode tab and the pressure contact between the negative electrode core exposed portion and the negative electrode tab are obtained by an eyelet pressure bonding method. It is preferable that it was performed by.
　正極芯体露出部と正極タブとの間の圧接及び負極芯体露出部と負極タブとの間の圧接は、芯体とタブを重ね合わせたところに針を貫通し、生じたバリを潰すことで圧着する、ハトメ圧着法を用いることができる。この方法は簡便でかつ確実に芯体とタブを接続することができるので、製造コストを安くすることができるようになる。 The pressure contact between the positive electrode core exposed portion and the positive electrode tab and the pressure contact between the negative electrode core exposed portion and the negative electrode tab penetrate the needle where the core and tab are overlapped, and crush the generated burr. The eyelet pressure bonding method can be used. Since this method can simply and reliably connect the core and the tab, the manufacturing cost can be reduced.
　また、本発明の非水電解質二次電池においては、前記正極芯体露出部と前記正極タブとの間の溶接または圧接及び前記負極芯体露出部と前記負極タブとの間の溶接または圧接は、それぞれ複数箇所で行われていることが好ましい。 Further, in the nonaqueous electrolyte secondary battery of the present invention, welding or pressure welding between the positive electrode core exposed portion and the positive electrode tab and welding or pressure welding between the negative electrode core exposed portion and the negative electrode tab are: These are preferably performed at a plurality of locations.
　正極芯体露出部と正極タブとの間の溶接または圧接及び負極芯体露出部と負極タブとの間の溶接または圧接を、それぞれ複数箇所で行うようにすると、正極芯体露出部ないし負極芯体露出部の厚さが薄くても正極タブ及び負極タブが動き難くなり、しかも接続強度が向上するので、寸法精度が高く、信頼性の高い非水電解質二次電池が得られる。 When welding or pressure welding between the positive electrode core exposed portion and the positive electrode tab and welding or pressure welding between the negative electrode core exposed portion and the negative electrode tab are performed at a plurality of locations, respectively, the positive electrode core exposed portion or the negative electrode core Even if the body exposed portion is thin, the positive electrode tab and the negative electrode tab are difficult to move, and the connection strength is improved, so that a non-aqueous electrolyte secondary battery with high dimensional accuracy and high reliability can be obtained.
　また、本発明の非水電解質二次電池においては、前記外装体は金属製の角形外装体であり、前記正極タブ及び前記負極タブの一方は前記金属製の角形外装体の開口部を閉鎖する金属製の封口板に直接電気的に接続されており、他方は、前記封口板に絶縁状態で取り付けられた端子部に電気的に接続されていることが好ましい。 In the nonaqueous electrolyte secondary battery of the present invention, the outer package is a metal rectangular outer package, and one of the positive electrode tab and the negative electrode tab closes an opening of the metal rectangular outer package. It is preferable that the metal sealing plate is electrically connected directly, and the other is electrically connected to a terminal portion attached to the sealing plate in an insulated state.
　本発明の非水電解質二次電池においては、外装体としてアルミニウムラミネートフィルムからなるものも使用することができる。しかしながら、外装体が、例えばアルミニウムやアルミニウム合金、外表面をニッケル等でメッキした鉄などの金属製の角形外装体であり、正極タブ及び負極タブの一方は金属製の角形外装体の開口部を閉鎖する金属製の封口板に直接電気的に接続されており、他方は、封口板に絶縁状態で取り付けられた端子部に電気的に接続されているものとすると、電池の機械的強度が強くなり、しかも、非水電解液の漏液が少なくなるようにすることができ、しかも寸法精度が向上する。加えて、金属の角形外装体及び封口板の材料を選択することにより、電池内部からの磁界が外部へ与える影響をより少なくすることもできる。 In the non-aqueous electrolyte secondary battery of the present invention, an exterior body made of an aluminum laminate film can also be used. However, the exterior body is a metal square exterior body such as aluminum or aluminum alloy, iron whose outer surface is plated with nickel, etc., and one of the positive electrode tab and the negative electrode tab has an opening of the metal square exterior body. If the metal sealing plate that is to be closed is electrically connected directly, and the other is electrically connected to a terminal portion that is attached to the sealing plate in an insulated state, the mechanical strength of the battery is high. In addition, the leakage of the non-aqueous electrolyte can be reduced, and the dimensional accuracy is improved. In addition, the influence of the magnetic field from the inside of the battery on the outside can be further reduced by selecting the materials for the metal rectangular outer casing and the sealing plate.
　また、正極タブと負極タブが接近して短絡することを防止するために、両極のタブが互いに重複しない（対向しない）ようにすることが好ましい。例えば、一方極の芯体露出部の長さと他方極の芯体露出部の長さを調整することにより、両極のタブが対向しないように配置することができる。 Also, in order to prevent the positive electrode tab and the negative electrode tab from approaching and short-circuiting, it is preferable that the tabs on both electrodes do not overlap (do not face each other). For example, by adjusting the length of the core exposed portion of one pole and the length of the core exposed portion of the other pole, the tabs of both poles can be arranged so as not to face each other.
実施例及び比較例に共通する偏平状巻回電極体と封口板との接続状況を示す斜視図である。It is a perspective view which shows the connection condition of the flat winding electrode body and sealing plate which are common in an Example and a comparative example. 図２Ａは実施例の正極極板と負極極板を重ね合わせた状態の展開図であり、図２Ｂは実施例の巻回電極体の正面図である。FIG. 2A is a development view showing a state in which the positive electrode plate and the negative electrode plate of the embodiment are overlapped, and FIG. 2B is a front view of the wound electrode body of the embodiment. 図３Ａは比較例の正極極板と負極極板を重ね合わせた状態の展開図であり、図３Ｂは比較例の巻回電極体の正面図である。FIG. 3A is a development view in which the positive electrode plate and the negative electrode plate of the comparative example are overlapped, and FIG. 3B is a front view of the wound electrode body of the comparative example. 図４Ａは実施例の正極極板及び負極極板の電流の流れの模式図であり、図４Ｂは比較例の正極極板及び負極極板の電流の流れの模式図である。FIG. 4A is a schematic diagram of the current flow of the positive electrode plate and the negative electrode plate of the example, and FIG. 4B is a schematic diagram of the current flow of the positive electrode plate and the negative electrode plate of the comparative example. 従来例の正極タブないし負極タブの構成を示す平面図である。It is a top view which shows the structure of the positive electrode tab thru | or negative electrode tab of a prior art example. 図６Ａは正極タブ及び負極タブの形成位置がそれぞれ両端側の場合の、図６Ｂは同じく同じ端部側の場合の、磁界の発生状況の説明図である。FIG. 6A is an explanatory diagram of a magnetic field generation state when the positive electrode tab and the negative electrode tab are formed at both end sides, and FIG. 6B is the same end portion side. 実施例及び比較例に共通する、磁界の計測箇所を示す平面模式図である。It is a plane schematic diagram which shows the measurement location of a magnetic field common to an Example and a comparative example. 別の従来例の正極極板ないし負極極板の斜視図である。It is a perspective view of the positive electrode plate thru | or negative electrode plate of another prior art example. 更に別の従来例の正極極板及び負極極板の斜視図である。It is a perspective view of the positive electrode plate and negative electrode plate of another prior art example.
　以下、本発明の実施形態を図面を用いて説明する。ただし、以下に示す実施形態は、本発明の技術思想を具体化するための角形非水電解質二次電池を例示するものであって、本発明をこの角形非水電解質二次電池に特定することを意図するものではなく、本発明は特許請求の範囲に示した技術思想を逸脱することなく種々の変更を行ったものにも均しく適用し得るものである。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment shown below exemplifies a rectangular non-aqueous electrolyte secondary battery for embodying the technical idea of the present invention, and the present invention is specified as this rectangular non-aqueous electrolyte secondary battery. However, the present invention can be equally applied to various modifications without departing from the technical idea shown in the claims.
　最初に、図１を参照して実施例及び比較例に共通する角形非水電解質二次電池の概略構成を説明する。なお、図１は、実施例及び比較例に共通する偏平状巻回電極体と封口板との接続状況を示す斜視図である。 First, a schematic configuration of a rectangular nonaqueous electrolyte secondary battery common to Examples and Comparative Examples will be described with reference to FIG. In addition, FIG. 1 is a perspective view which shows the connection condition of the flat wound electrode body and sealing plate which are common in an Example and a comparative example.
　この非水電解質二次電池の偏平状巻回電極体１０は、例えば外周側に正極極板が、内周側に負極極板が配置され、それぞれセパレータ（何れも図示省略）を介して偏平状に巻回され、巻き終わり端部が絶縁テープ１１によって絶縁されている。この偏平状巻回電極体１０には、正極芯体露出部に正極タブ１２が接続されており、負極芯体露出部には負極タブ１３が接続されている。また、偏平状巻回電極体１０には、上面及び下面にはそれぞれ絶縁スペーサ１４及び１５が配置され、正極タブ１２は上側の絶縁スペーサ１４の外周側を通って折り曲げられて封口板１６の内面に抵抗溶接されており、また、負極タブ１３は上側の絶縁スペーサ１４に形成されたスリット１７内を通して封口板１６に形成された負極端子１８に抵抗溶接されている。 The flat wound electrode body 10 of this non-aqueous electrolyte secondary battery has, for example, a positive electrode plate disposed on the outer peripheral side and a negative electrode plate disposed on the inner peripheral side, and is flattened via separators (both not shown). The end of the winding is insulated by the insulating tape 11. The flat wound electrode body 10 has a positive electrode tab 12 connected to a positive electrode core exposed portion and a negative electrode tab 13 connected to a negative electrode core exposed portion. Further, the flat wound electrode body 10 is provided with insulating spacers 14 and 15 on the upper surface and the lower surface, respectively, and the positive electrode tab 12 is bent through the outer peripheral side of the upper insulating spacer 14 to be the inner surface of the sealing plate 16. The negative electrode tab 13 is resistance-welded to a negative electrode terminal 18 formed on the sealing plate 16 through a slit 17 formed in the upper insulating spacer 14.
　なお、この偏平状巻回電極体１０は、図示省略したが、長手方向の一端面が開口し、周囲面が閉鎖したほぼ偏平状の導電性を有する箱型の電池外装缶内に挿入され、開口部が封口板１６によって封口され、電池外装缶の開口端縁と封口板１６との間をレーザ溶接することにより封口され、その後、電解液注入孔１９より所定量の非水電解液が注入され、この電解液注入孔１９を封止することによって作製される。 Although the flat wound electrode body 10 is not shown in the drawing, it is inserted into a substantially flat conductive box-type battery outer casing whose one end surface in the longitudinal direction is open and whose peripheral surface is closed, The opening is sealed by the sealing plate 16 and sealed by laser welding between the opening edge of the battery outer can and the sealing plate 16, and then a predetermined amount of nonaqueous electrolyte is injected from the electrolyte injection hole 19. The electrolyte solution injection hole 19 is sealed.
　次いで、実施例及び比較例の正極極板及び負極極板の具体的構成及びそれぞれの巻回電極体の平面図を図２及び図３を用いて説明する。なお、図２Ａは実施例の正極極板と負極極板を重ね合わせた状態の展開図であり、図２Ｂは実施例の巻回電極体１０Ａの平面図である。図３Ａは比較例の正極極板と負極極板を重ね合わせた状態の展開図であり、図３Ｂは比較例の巻回電極体１０Ｂの平面図である。なお、図２Ａ及び図３Ａにおいては、セパレータは図示省略されている。 Next, specific configurations of the positive electrode plate and the negative electrode plate of Examples and Comparative Examples and plan views of the respective wound electrode bodies will be described with reference to FIGS. 2 and 3. 2A is a development view in which the positive electrode plate and the negative electrode plate of the example are overlapped, and FIG. 2B is a plan view of the wound electrode body 10A of the example. FIG. 3A is a development view in which the positive electrode plate and the negative electrode plate of the comparative example are overlapped, and FIG. 3B is a plan view of the wound electrode body 10B of the comparative example. 2A and 3A, the separator is not shown.
　実施例の正極極板及び負極極板と比較例の正極極板及び負極極板との構成の差異は、正極芯体露出部及び負極芯体露出部の形状と、正極タブ及び負極タブの溶接状態であるので、以下では共通する構成部分には同一の参照符号を付与して説明することとする。 The difference in configuration between the positive electrode plate and negative electrode plate of the example and the positive electrode plate and negative electrode plate of the comparative example is the shape of the positive electrode core exposed portion and the negative electrode core exposed portion, and the welding of the positive electrode tab and the negative electrode tab. Since it is in a state, hereinafter, the same reference numerals are given to the common components to be described.
［正極極板の作製］
　正極活物質としてコバルト酸リチウムと、炭素系導電剤であるアセチレンブラックと、ＰＶＤＦ（ポリフッ化ビニリデン）を、９５：２．５：２．５の質量比で混合して、ＮＭＰ（Ｎ－メチルピロリドン）を溶剤として混合機を用いて混合し、正極合剤スラリーを調製した。このスラリーを厚さ１３μｍのアルミニウム製の正極芯体２１の両面にドクターブレード法により塗布、乾燥して、正極芯体２１の両面に正極活物質層２２を形成した。その後、圧縮ローラーを用いて圧縮し、短辺の長さが４３ｍｍの正極極板を作製した。 [Preparation of positive electrode plate]
Lithium cobaltate as a positive electrode active material, acetylene black as a carbon-based conductive agent, and PVDF (polyvinylidene fluoride) are mixed at a mass ratio of 95: 2.5: 2.5 to obtain NMP (N-methylpyrrolidone). ) As a solvent using a mixer to prepare a positive electrode mixture slurry. This slurry was applied to both surfaces of a 13 μm thick aluminum positive electrode core 21 by a doctor blade method and dried to form positive electrode active material layers 22 on both surfaces of the positive electrode core 21. Then, it compressed using the compression roller and produced the positive electrode plate whose short side length is 43 mm.
［負極極板の作製］
　人造黒鉛と、カルボキシメチルセルロース（ＣＭＣ）を純水に１質量％溶解させたものと、スチレンブタジエンゴム（ＳＢＲ）とを固形分比で９８：１：１の質量比となるように、混練して負極合剤スラリーを作製した。次いで、厚さ８μｍの銅製の負極芯体２５の両面にドクターブレード法により塗布後、乾燥して負極芯体２５の両面に負極活物質層２６を形成した。この後、圧縮ローラーを用いて圧縮し、短辺の長さが４４ｍｍの負極極板を作製した。 [Production of negative electrode plate]
A mixture of artificial graphite, carboxymethyl cellulose (CMC) dissolved in 1% by mass in pure water, and styrene butadiene rubber (SBR) were mixed so that the solid content ratio was 98: 1: 1. A negative electrode mixture slurry was prepared. Next, the negative electrode active material layer 26 was formed on both surfaces of the negative electrode core 25 by applying it to both surfaces of the copper negative electrode core 25 having a thickness of 8 μm by a doctor blade method and then drying. Then, it compressed using the compression roller and produced the negative electrode plate whose length of a short side is 44 mm.
［非水電解液の調製］
　非水電解液は、ＬｉＰＦ６を１ｍｏｌ／Ｌの濃度になるようにエチレンカーボネート、エチルメチルカーボネート及びジエチルカーボネートの体積混合比が４０：３０：３０の混合溶媒に溶解した非水電解液を用いた。 [Preparation of non-aqueous electrolyte]
As the non-aqueous electrolyte, a non-aqueous electrolyte obtained by dissolving LiPF 6 in a mixed solvent having a volume mixing ratio of ethylene carbonate, ethyl methyl carbonate and diethyl carbonate of 40:30:30 so as to have a concentration of 1 mol / L was used. .
［正極タブ及び負極タブの取り付け］
　この正極極板２０には、正極芯体２１の巻回終端となる部分から一定の距離だけ正極芯体２１の両面ともに正極活物質層２２を有しない正極芯体露出部が設けられているが、実施例の正極芯体露出部２１ａ及び比較例の正極芯体露出部２１ｂの長さは共に３５ｍｍとされ、実施例の正極芯体露出部２１ａの幅は、正極極板２０の幅の１／２以下、具体的には５ｍｍと細くされており、それに対して比較例の正極芯体露出部２１ｂの幅は、正極極板２０の幅と同一とされている。 [Attaching the positive and negative electrode tabs]
The positive electrode plate 20 is provided with a positive electrode core exposed portion that does not have the positive electrode active material layer 22 on both surfaces of the positive electrode core 21 at a certain distance from the winding end portion of the positive electrode core 21. The lengths of the positive electrode core exposed part 21a of the example and the positive electrode core exposed part 21b of the comparative example are both 35 mm, and the width of the positive electrode core exposed part 21a of the example is 1 of the width of the positive electrode plate 20. The width of the positive electrode core exposed portion 21b of the comparative example is the same as the width of the positive electrode plate 20, whereas the width is 1/2 mm or less, specifically 5 mm.
　また、負極極板２４には、負極芯体２５の巻回終端から一定の距離だけ負極芯体２５の両面ともに負極活物質層２６を有しない負極芯体露出部が設けられているが、実施例の負極芯体露出部２５ａ及び比較例の負極芯体露出部２５ｂの長さは共に１５ｍｍとされ、実施例の負極芯体露出部２５ａの幅は、負極極板２４の幅の１／２以下、具体的には６ｍｍと細くされており、それに対して比較例の負極芯体露出部２５ｂの幅は、負極極板２４の幅と同一とされている。そのため、実施例の巻回電極体１０Ａには、図２Ｂに示したように、最外周側の上部にのみ、正極芯体露出部２１ａの巻回部分が形成される。また、比較例の巻回電極体１０Ｂには、図３Ｂに示したように、最外周側の全幅にわたって正極芯体露出部２１ｂの巻回部分が形成され、正極芯体露出部２１ｂが大きく露出するようになる。 In addition, the negative electrode plate 24 is provided with a negative electrode core exposed portion that does not have the negative electrode active material layer 26 on both surfaces of the negative electrode core 25 by a certain distance from the winding end of the negative electrode core 25. The length of the negative electrode core exposed portion 25a in the example and the length of the negative electrode core exposed portion 25b in the comparative example are both 15 mm, and the width of the negative electrode core exposed portion 25a in the example is 1/2 of the width of the negative electrode plate 24. Hereinafter, the thickness is specifically reduced to 6 mm, and the width of the negative electrode core exposed portion 25 b of the comparative example is made the same as the width of the negative electrode plate 24. Therefore, in the wound electrode body 10A of the example, as shown in FIG. 2B, the wound portion of the positive electrode core exposed portion 21a is formed only on the uppermost outermost side. Further, as shown in FIG. 3B, the wound electrode body 10B of the comparative example is formed with the wound portion of the positive electrode core exposed portion 21b over the entire width on the outermost peripheral side, and the positive electrode core exposed portion 21b is greatly exposed. To come.
　上述したように、比較例の正極芯体露出部２１ｂ及び負極芯体露出部２５ｂは、それぞれ正極極板２０及び負極極板２４の幅と同じ幅、すなわち、正極芯体２１及び負極芯体２５共に全長にわたってそれぞれ同一幅となされている。また、正極タブ１２ａとしてはアルミニウム金属製の厚さ０．１ｍｍ、幅３ｍｍ、長さ５０ｍｍのものを用い、負極タブ１３ｂとしてはニッケル金属製の厚さ０．１ｍｍ、幅３ｍｍ、長さ５０ｍｍのものを用い、それぞれ正極芯体露出部２１ｂないし負極芯体露出部２５ｂと接触する長さ４２ｍｍに対して、上から４ｍｍ、下から３ｍｍの区間を５ｍｍ間隔で８箇所、スポット的に超音波溶接した。 As described above, the positive electrode core exposed portion 21b and the negative electrode core exposed portion 25b of the comparative example have the same width as the positive electrode plate 20 and the negative electrode plate 24, that is, the positive electrode core 21 and the negative electrode core 25, respectively. Both have the same width over the entire length. The positive electrode tab 12a is made of aluminum metal having a thickness of 0.1 mm, a width of 3 mm, and a length of 50 mm, and the negative electrode tab 13b is made of nickel metal having a thickness of 0.1 mm, a width of 3 mm, and a length of 50 mm. For each of 42 mm in length, which is in contact with the positive electrode core exposed part 21b or the negative electrode core exposed part 25b, spot welding is performed by spot welding at 8 locations at intervals of 5 mm at intervals of 4 mm from the top and 3 mm from the bottom. did.
　それに対し、実施例の正極芯体露出部２１ａ及び負極芯体露出部２５ａは、それぞれ正極極板２０及び負極極板４０の幅の１／２以下としているため、正極タブ１２ａとしてはアルミニウム金属製の厚さ０．１ｍｍ、幅３ｍｍ、長さ１０ｍｍのものを用い、負極タブ１３ｂとしてはニッケル金属製の厚さ０．１ｍｍ、幅３ｍｍ、長さ１０ｍｍのものを用いており、正極タブ１２ａないし負極タブ１３ａとの接触長さが短いので、正極タブ１２ａないし負極タブ１３ａと正極芯体露出部２１ａ及び負極芯体露出部２５ａとは、例えば２箇所、等間隔で超音波溶接を行った。 On the other hand, since the positive electrode core exposed portion 21a and the negative electrode core exposed portion 25a of the embodiment are set to ½ or less of the width of the positive electrode plate 20 and the negative electrode plate 40, respectively, the positive electrode tab 12a is made of aluminum metal. The negative electrode tab 13b is made of nickel metal with a thickness of 0.1 mm, a width of 3 mm, and a length of 10 mm. Since the contact length with the negative electrode tab 13a is short, the positive electrode tab 12a thru | or the negative electrode tab 13a, the positive electrode core body exposed part 21a, and the negative electrode core body exposed part 25a were ultrasonically welded, for example, at two places.
　なお、実施例における正極タブ１２ａないし負極タブ１３ａと正極芯体露出部２１ａ及び負極芯体露出部２５ａとの溶接点は、それぞれ１箇所ずつでもよいが、正極芯体露出部２１ａ及び負極芯体露出部２５ａは機械的強度が弱いために、溶接箇所が１箇所であると正極タブ１２ａないし負極タブ１３ａが回動しやすく、電池の組み立て時に正極タブ１２ａないし負極タブ１３ａの位置が変化しやすい。そのため、実施例における正極タブ１２ａないし負極タブ１３ａと正極芯体露出部２１ａ及び負極芯体露出部２５ａとの溶接点は、２箇所以上とすることが望ましい。 In addition, the positive electrode tab 12a thru | or the negative electrode tab 13a and the welding point of the positive electrode core body exposed part 21a and the negative electrode core body exposed part 25a may be one each, but the positive electrode core body exposed part 21a and the negative electrode core body Since the exposed portion 25a is weak in mechanical strength, the positive electrode tab 12a or the negative electrode tab 13a is easily rotated when the number of welded portions is one, and the position of the positive electrode tab 12a or the negative electrode tab 13a is likely to change during battery assembly. . Therefore, it is desirable that the number of welding points between the positive electrode tab 12a or the negative electrode tab 13a, the positive electrode core exposed portion 21a, and the negative electrode core exposed portion 25a in the embodiment be two or more.
［偏平状巻回電極体の作製］
　上述のようにして作製した正極極板２０と負極極板２４とを、外周側が正極極板２０となるようにして、ポリエチレン製微多孔膜からなるセパレータを挟んで互いに絶縁した状態で巻回し、巻き終わり端部を絶縁テープ１１によって固定し、押し潰すことによって実施例の偏平状巻回電極体１０Ａ及び比較例の巻回電極体１０Ｂを作製した。なお、それぞれの偏平状巻回電極体１０Ａ、１０Ｂの上部からは正極タブ１２ａ、１２ｂ及び負極タブ１３ａ、１３ｂを突出させた。この偏平状巻回電極体１０Ａ、１０Ｂの概略構成はそれぞれ図２Ｂ、図３Ｂに示したとおりとなる。 [Preparation of flat wound electrode body]
The positive electrode plate 20 and the negative electrode plate 24 produced as described above are wound in a state where the outer peripheral side is the positive electrode plate 20 and insulated from each other with a separator made of a polyethylene microporous film interposed therebetween, The end portion of the winding was fixed with the insulating tape 11 and crushed to produce the flat wound electrode body 10A of the example and the wound electrode body 10B of the comparative example. In addition, the positive electrode tabs 12a and 12b and the negative electrode tabs 13a and 13b were protruded from the upper portions of the respective flat wound electrode bodies 10A and 10B. The schematic configurations of the flat wound electrode bodies 10A and 10B are as shown in FIGS. 2B and 3B, respectively.
［非水電解質二次電池の作製］
　次いで、このようにして作製された偏平状巻回電極体１０Ａ、１０Ｂは、図示省略したが、長手方向の一端面が開口し、周囲面が閉鎖したほぼ偏平状の導電性を有する箱型の電池外装缶内に挿入し、開口部を封口板１６によって封口し、電池外装缶の開口端縁と封口板１６との間をレーザ溶接することにより封口し、その後、電解液注入孔１９より所定量の非水電解液を注入し、この電解液注入孔１９を封止することにより、実施例及び比較例に対応する非水電解質二次電池を作製した。なお、得られた非水電解質二次電池の寸法は、厚み５．２ｍｍ×幅３４ｍｍ×高さ５０ｍｍであり、設計容量は１１５０ｍＡｈである。 [Production of non-aqueous electrolyte secondary battery]
Next, the flat wound electrode bodies 10A and 10B manufactured in this way are not shown in the figure, but are substantially flat conductive with one end surface in the longitudinal direction opened and the peripheral surface closed. It is inserted into the battery outer can, the opening is sealed with the sealing plate 16, and sealed between the opening edge of the battery outer can and the sealing plate 16 by laser welding. Non-aqueous electrolyte secondary batteries corresponding to Examples and Comparative Examples were manufactured by injecting a fixed amount of non-aqueous electrolyte and sealing the electrolyte injection hole 19. The dimensions of the obtained nonaqueous electrolyte secondary battery are thickness 5.2 mm × width 34 mm × height 50 mm, and the design capacity is 1150 mAh.
［放電により生じる磁界の計測］
　このようにして作製された実施例及び比較例のそれぞれの非水電解質二次電池について、１Ｉｔ＝１１５０ｍＡの定電流で電池電圧が４．２Ｖになるまで充電し、電池電圧が４、２Ｖに達した後は４．２Ｖの定電圧で充電電流が２３ｍＡになるまで充電して満充電状態とした。次いで、１Ｉｔ＝１１５０ｍＡの定電流で放電して電池の状態を整えた。 [Measurement of magnetic field generated by discharge]
The non-aqueous electrolyte secondary batteries of Examples and Comparative Examples thus fabricated were charged until the battery voltage reached 4.2 V at a constant current of 1 It = 1150 mA, and the battery voltage reached 4, 2 V. After that, the battery was charged at a constant voltage of 4.2 V until the charging current became 23 mA to be in a fully charged state. Next, the battery was conditioned by discharging at a constant current of 1 It = 1150 mA.
　状態を整えた電池を上述と同じ条件で充電を行い、負極端子１８の電池表面側と封口板１６（正極）とにそれぞれリード線の一端を接続した。リード線に流れる電流による磁界の影響をなくすために、互いのリード線を撚り合した。そして、リード線の他端を電源の出力端子に接続し、電源を用いてＧＳＭ仕様のパルス波形の放電負荷を電池に与えながら、電池周囲の磁界を測定した。ＧＳＭ仕様のパルス波形形状は、周波数２１７Ｈｚで電流２Ａが０．６ミリ秒間、０．１Ａが１．４ミリ秒間である。 The prepared battery was charged under the same conditions as described above, and one end of each lead wire was connected to the battery surface side of the negative electrode terminal 18 and the sealing plate 16 (positive electrode). In order to eliminate the influence of the magnetic field due to the current flowing in the lead wires, the lead wires were twisted together. Then, the other end of the lead wire was connected to the output terminal of the power supply, and the magnetic field around the battery was measured while applying a discharge load having a pulse waveform of GSM specifications to the battery using the power supply. The pulse waveform shape of the GSM specification is that the frequency is 217 Hz, the current 2A is 0.6 milliseconds, and 0.1 A is 1.4 milliseconds.
　磁界の計測方法としては、まず、実施例及び比較例のそれぞれの非水電解質二次電池について、電池の面積が最大である側面を上下向きで静置し、電池の側面の上方１ｃｍの平面上を磁界測定コイルを移動させて磁場の強さを測定した。電池を中心とした１８ｃｍ×１３ｃｍの範囲を縦方向、横方向に１ｃｍごとに区切った点を測定点とする、１９×１４＝２６６箇所を測定した。次いで、測定された磁場の強さを基に、図７に示される８箇所について磁界の大きさを求めた。結果を表１に示す。 As a method for measuring the magnetic field, first, for each of the nonaqueous electrolyte secondary batteries of the example and the comparative example, the side where the area of the battery is the maximum is left in the vertical direction, and the plane is 1 cm above the side of the battery. The magnetic field strength was measured by moving the magnetic field measuring coil. 19 × 14 = 266 locations were measured, with the points obtained by dividing the range of 18 cm × 13 cm centered on the battery in the vertical and horizontal directions every 1 cm. Next, based on the measured strength of the magnetic field, the magnitude of the magnetic field was obtained at 8 locations shown in FIG. The results are shown in Table 1.
　なお、図７は、電池の面積が最大である側面を上下向きで静置した状態を平面視した平面模式図であり、電池内部の偏平状巻回電極体１０の上部側（封口板１６を備えている側）が左側となるように配置しており、電池の高さ方向をｘ軸、幅方向をｙ軸、厚み方向をｚ軸（図示しない）と定めた。 FIG. 7 is a plan view schematically showing a state in which the side surface having the largest battery area is left in a vertical direction. The upper side of the flat wound electrode body 10 inside the battery (the sealing plate 16 is shown). The height direction of the battery is defined as the x-axis, the width direction is defined as the y-axis, and the thickness direction is defined as the z-axis (not shown).
　また、表１は、図７に示される８箇所（但し、電池表面からｚ軸方向に１ｃｍ離れた平面上に位置する）における磁場の強さについて、ｘｙｚ各方向の磁界の大きさ（単位：ｄＢ・Ａ／ｍ）として示している。ｄＢ・Ａ／ｍへの換算に当っては、比較例の図７の丸付き数字２の位置におけるｘ軸方向の磁場強さを基準とした。 Table 1 also shows the magnetic field strength (unit: xyz) in the xyz directions with respect to the strength of the magnetic field at 8 locations shown in FIG. 7 (however, located on a plane 1 cm away from the battery surface in the z-axis direction). dB · A / m). In conversion to dB · A / m, the magnetic field strength in the x-axis direction at the position of the circled numeral 2 in FIG.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１によると、比較例では－１０ｄＢ・Ａ／ｍより大きな磁界の発生がｘｙｚの各方向に対して見られる。これに対して実施例では８箇所全てにおいて磁界の大きさが－１０ｄＢ・Ａ／ｍ以下であり、放電により生じる磁界の大きさが抑制されていることが判る。このような現象が生じる理由は、以下のとおりであると考えられる。 According to Table 1, in the comparative example, generation of a magnetic field larger than −10 dB · A / m can be seen in each direction of xyz. On the other hand, in the example, the magnitude of the magnetic field is -10 dB · A / m or less in all eight places, and it can be seen that the magnitude of the magnetic field generated by the discharge is suppressed. The reason why such a phenomenon occurs is considered as follows.
　すなわち、実施例の正極極板２０及び負極極板２４では、正極芯体露出部２１ａないし負極芯体露出部２５ａは、いずれも正極極板２０ないし負極極板２４の幅と等しい部分が存在せず、正極活物質層２２ないし負極活物質層２６の形成部分から直ちに一定の細い幅に形成されている。そのため、実施例の正極極板２０及び負極極板２４では、正極タブ１２ａないし負極タブ１３ａと正極芯体露出部２１ａないし負極芯体露出部２５ａとの間の溶接点同士が離間していても、正極芯体露出部２１ａないし負極芯体露出部２５ａを流れる電流の向きは、図４Ａに示したように、互いに反対方向で、平行となっているので、それぞれの極板に流れる電流に起因する磁界は打ち消し合うので、外部に漏れてくる磁界の大きさは小さくなる。 That is, in the positive electrode plate 20 and the negative electrode plate 24 of the embodiment, the positive electrode core exposed portion 21a to the negative electrode core exposed portion 25a are not present in the same part as the width of the positive electrode plate 20 to the negative electrode plate 24. In other words, the positive electrode active material layer 22 or the negative electrode active material layer 26 is formed to have a constant narrow width immediately from the formation portion. Therefore, in the positive electrode plate 20 and the negative electrode plate 24 of the embodiment, even if the welding points between the positive electrode tab 12a or the negative electrode tab 13a and the positive electrode core exposed portion 21a or the negative electrode core exposed portion 25a are separated from each other. The direction of the current flowing through the positive electrode core exposed portion 21a or the negative electrode core exposed portion 25a is parallel to each other in the opposite direction as shown in FIG. 4A. Since the magnetic fields to be canceled out, the magnitude of the magnetic field leaking to the outside is reduced.
　それに対し、比較例の正極極板２０及び負極極板２４では、正極芯体露出部２１ｂないし負極芯体露出部２５ｂは、いずれも正極極板２０ないし負極極板２４の形成部分の幅と等しくなっている。また、非水電解質二次電池では、負極極板へのリチウムデンドライト生成を抑制するため、正極極板２０よりも負極極板２４の方が面積が大きくなるように作製されている。 On the other hand, in the positive electrode plate 20 and the negative electrode plate 24 of the comparative example, the positive electrode core exposed portion 21b to the negative electrode core exposed portion 25b are all equal to the width of the formed portion of the positive electrode plate 20 to the negative electrode plate 24. It has become. Further, in the nonaqueous electrolyte secondary battery, the negative electrode plate 24 has a larger area than the positive electrode plate 20 in order to suppress generation of lithium dendrite on the negative electrode plate.
　そのため、比較例の正極極板２０及び負極極板２４では、図４Ｂに示したように、それぞれの活物質層形成領域側から流れる電流は、それぞれの電極タブの溶接点へ最短距離で流れようとするが、少なくとも負極極板２４側では下側の負極活物質層２６から電池の上側（負極タブ１３ｂが形成されている側）に流れる成分が生じる。この負極極板側２４での下側の負極活物質層２６から上側に流れる電流によって形成される磁界は、正極極板２０に流れる電流によって形成される磁界によって打ち消されないので、外部に漏出する磁界が十分小さくならず補聴器等に悪影響を与える可能性が高くなる。 Therefore, in the positive electrode plate 20 and the negative electrode plate 24 of the comparative example, as shown in FIG. 4B, the current flowing from each active material layer forming region side should flow to the welding point of each electrode tab at the shortest distance. However, at least on the negative electrode plate 24 side, a component that flows from the lower negative electrode active material layer 26 to the upper side of the battery (the side where the negative electrode tab 13b is formed) is generated. The magnetic field formed by the current flowing upward from the lower negative electrode active material layer 26 on the negative electrode plate side 24 is not canceled by the magnetic field formed by the current flowing through the positive electrode plate 20, and therefore leaks to the outside. The magnetic field is not sufficiently small, and there is a high possibility that the hearing aid will be adversely affected.
　なお、上記実施例においては、図２及び４に示したように、正極芯体露出部２１ａ及び負極芯体露出部２５ａを、電池上部側（正極タブ１２ａ及び負極タブ１３ａの突出側）に形成した例を用いたが、正極芯体露出部２１ａ及び負極芯体露出部２５ａが重なる位置に形成されていれば、電池上部側でなくとも本発明は実施可能である。 2 and 4, the positive electrode core exposed portion 21a and the negative electrode core exposed portion 25a are formed on the upper side of the battery (the protruding side of the positive electrode tab 12a and the negative electrode tab 13a). However, as long as the positive electrode core body exposed portion 21a and the negative electrode core body exposed portion 25a are formed at overlapping positions, the present invention can be carried out even if it is not on the upper side of the battery.
　別途行ったシミュレーションの結果からは、正極芯体露出部２１ａ及び負極芯体露出部２５ａを、巻回電極体の幅方向に対して中央部よりに形成されたもの程、発生する磁界が小さくなる傾向が見られた。従って、正極芯体露出部２１ａ及び負極芯体露出部２５ａを、巻回電極体の巻回軸方向における中央部に形成することがより好ましい。 From the results of the simulation performed separately, the magnetic field generated becomes smaller as the positive electrode core exposed portion 21a and the negative electrode core exposed portion 25a are formed closer to the center in the width direction of the wound electrode body. There was a trend. Therefore, it is more preferable to form the positive electrode core exposed portion 21a and the negative electrode core exposed portion 25a at the central portion in the winding axis direction of the wound electrode body.
　以上述べたように、本実施例の非水電解質二次電池によれば、従来例に対応する比較例の非水電解質二次電池よりも、電池内部に流れる電流による磁界が発生し難いため、補聴器等の使用者に対して悪影響を及ぼすことが抑制されるようになる。 As described above, according to the non-aqueous electrolyte secondary battery of this example, a magnetic field due to the current flowing in the battery is less likely to occur than the non-aqueous electrolyte secondary battery of the comparative example corresponding to the conventional example. An adverse effect on a user such as a hearing aid is suppressed.
　なお、上記実施例においては、巻回電極体の巻き終わり側に、正極芯体露出部及び負極芯体露出部を設けて正極タブ及び負極タブを取り付けた非水電解質二次電池を示したが、本発明は正極極板中に流れる電流と負極極板中に流れる電流とが反対方向に流れるようになすことで効果が奏されるため、巻回電極体の巻き取り始め側と巻き終わり側のどちらか一方に、正極タブ及び負極タブの双方が設けられており、かつ、正極タブ及び負極タブが巻回電極体の巻回軸方向に対して同じ方向に導出されていれば、正極タブ及び負極タブが、巻回電極体の巻き始め側に設けられていても、巻き終わり側に設けられていても、本発明は実施可能である。 In the above embodiment, the nonaqueous electrolyte secondary battery in which the positive electrode core exposed portion and the negative electrode core exposed portion are provided on the winding end side of the wound electrode body and the positive electrode tab and the negative electrode tab are attached is shown. Since the present invention is effective when the current flowing in the positive electrode plate and the current flowing in the negative electrode plate flow in opposite directions, the winding start side and the winding end side of the wound electrode body If either one of the positive electrode tab and the negative electrode tab is provided on both of them, and the positive electrode tab and the negative electrode tab are led out in the same direction with respect to the winding axis direction of the wound electrode body, the positive electrode tab Even if the negative electrode tab is provided on the winding start side or the winding end side of the wound electrode body, the present invention can be implemented.
　１０、１０Ａ、１０Ｂ…偏平状巻回電極体　１１…絶縁テープ　１２、１２ａ、１２ｂ…正極タブ　１３、１３ａ、１３ｂ…負極タブ　１４、１５…絶縁スペーサ　１６…封口板　１７…スリット　１８…負極端子　１９…電解液注入孔　２０…正極極板　２１…正極芯体　２１ａ、２１ｂ…正極芯体露出部　２２…正極活物質層　２４…負極極板　２５…負極芯体　２５ａ、２５ｂ…負極芯体露出部　２６…負極活物質層　２８ａ、２８ｂ…巻回電極体　３０ａ、３０ｂ…セパレータ DESCRIPTION OF SYMBOLS 10, 10A, 10B ... Flat winding electrode body 11 ... Insulation tape 12, 12a, 12b ... Positive electrode tab 13, 13a, 13b ... Negative electrode tab 14, 15 ... Insulation spacer 16 ... Sealing plate 17 ... Slit 18 ... Negative electrode terminal 19 Electrolyte injection hole 20 ... Positive electrode plate 21 ... Positive electrode core 21a, 21b ... Positive electrode core exposed portion 22 ... Positive electrode active material layer 24 ... Negative electrode plate 25 ... Negative electrode core 25a, 25b ... Negative electrode core exposed portion 26 ... negative electrode active material layers 28a, 28b ... wound electrode bodies 30a, 30b ... separators

Claims (6)

  1. 　正極合剤層が正極芯体の両面に塗布された正極極板と、負極活物質層が負極芯体の両面に塗布された負極極板とが、それぞれセパレータを挟んで巻回された偏平状の巻回電極体と、前記偏平状の巻回電極体を収納する外装体と、前記外装体内に注入された非水電解液と、を備える非水電解質二次電池において、
    　前記正極極板は、前記正極極板の巻き始め側又は巻き終わり側に前記正極極板の幅の１／２よりも短い幅の正極芯体露出部が形成され、前記正極芯体露出部には正極タブが溶接または圧接されており、
    　前記負極極板は、前記正極芯体露出部と同じ側に、前記負極極板の幅の１／２よりも短い幅の負極芯体露出部が形成されて、前記正極芯体露出部と前記負極芯体露出部とが前記セパレータを介して対向しており、前記負極芯体露出部には負極タブが溶接または圧接されており、
    　前記正極タブ及び前記負極タブは、前記巻回電極体の巻回軸方向に対して同じ方向に導出されていることを特徴とする非水電解質二次電池。     A flat plate in which a positive electrode plate in which a positive electrode mixture layer is applied to both surfaces of a positive electrode core and a negative electrode plate in which a negative electrode active material layer is applied to both surfaces of the negative electrode core are wound with a separator interposed therebetween. A non-aqueous electrolyte secondary battery comprising: a wound electrode body; an exterior body housing the flat wound electrode body; and a non-aqueous electrolyte injected into the exterior body.
    In the positive electrode plate, a positive electrode core exposed portion having a width shorter than ½ of the width of the positive electrode plate is formed on a winding start side or a winding end side of the positive electrode plate, and the positive electrode core exposed portion The positive electrode tab is welded or pressed,
    The negative electrode plate has a negative electrode core exposed portion having a width shorter than ½ of the width of the negative electrode plate on the same side as the positive electrode core exposed portion, and the positive electrode core exposed portion and the The negative electrode core exposed portion is opposed to the negative electrode core through the separator, and a negative electrode tab is welded or pressed to the negative electrode core exposed portion,
    The non-aqueous electrolyte secondary battery, wherein the positive electrode tab and the negative electrode tab are led out in the same direction with respect to a winding axis direction of the wound electrode body.
  2. 　前記正極芯体露出部及び前記負極芯体露出部は、前記巻回電極体の巻回軸方向における中央部に形成されていることを特徴とする請求項１に記載の非水電解質二次電池。 2. The nonaqueous electrolyte secondary battery according to claim 1, wherein the positive electrode core body exposed portion and the negative electrode core body exposed portion are formed at a central portion in a winding axis direction of the wound electrode body. .
  3. 　前記正極芯体露出部と前記正極タブとの間の溶接及び前記負極芯体露出部と前記負極タブとの間の溶接は、抵抗溶接法又は超音波溶接法によって行われたものであることを特徴とする請求項１に記載の非水電解質二次電池。 The welding between the positive electrode core exposed portion and the positive electrode tab and the welding between the negative electrode core exposed portion and the negative electrode tab are performed by a resistance welding method or an ultrasonic welding method. The non-aqueous electrolyte secondary battery according to claim 1.
  4. 　前記正極芯体露出部と前記正極タブとの間の圧接及び前記負極芯体露出部と前記負極タブとの間の圧接は、ハトメ圧着によって行われたものであることを特徴とする請求項１に記載の非水電解質二次電池。 2. The pressure contact between the positive electrode core exposed portion and the positive electrode tab and the pressure contact between the negative electrode core exposed portion and the negative electrode tab are performed by eyelet pressure bonding. The non-aqueous electrolyte secondary battery described in 1.
  5. 　前記正極芯体露出部と前記正極タブとの間の溶接または圧接及び前記負極芯体露出部と前記負極タブとの間の溶接または圧接は、それぞれ複数箇所で行われていることを特徴とする請求項１に記載の非水電解質二次電池。 Welding or pressure welding between the positive electrode core exposed portion and the positive electrode tab and welding or pressure welding between the negative electrode core exposed portion and the negative electrode tab are each performed at a plurality of locations. The nonaqueous electrolyte secondary battery according to claim 1.
  6. 　前記外装体は金属製の角形外装体であり、前記正極タブ及び前記負極タブの一方は前記金属製の角形外装体の開口部を閉鎖する金属製の封口板に直接電気的に接続されており、他方は、前記封口板に絶縁状態で取り付けられた端子部に電気的に接続されていることを特徴とする請求項１～５のいずれかに記載の非水電解質二次電池。 The exterior body is a metal square exterior body, and one of the positive electrode tab and the negative electrode tab is directly electrically connected to a metal sealing plate that closes an opening of the metal square exterior body. 6. The nonaqueous electrolyte secondary battery according to claim 1, wherein the other is electrically connected to a terminal portion attached to the sealing plate in an insulated state.
PCT/JP2011/074062 2010-10-20 2011-10-19 Non-aqueous electrolyte secondary cell WO2012053556A1 (en)

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