JP5432746B2 - Lithium ion secondary battery - Google Patents

Description

  The present invention relates to a lithium ion secondary battery.

  From the viewpoints of environmental protection and energy saving, hybrid vehicles using an engine and a motor as a power source have been developed and commercialized. In the future, fuel cell hybrid vehicles that use fuel cells instead of engines are also actively developed.

  A secondary battery capable of repeatedly charging and discharging electricity as an energy source of this hybrid vehicle is an essential technology.

  Among them, the lithium ion secondary battery is a battery having a high operating voltage and a high energy density that easily obtains a high output, and is increasingly important as a power source for a hybrid vehicle in the future.

  High power, high energy density, and long life are important issues in the application of hybrid vehicles to electric vehicles.

  In Patent Document 1, an active material powder, conductive fibers, and a binder resin are uniformly mixed, applied to a polytetrafluoroethylene (PTFE) plate or the like to a predetermined thickness, dried, and sheet-shaped. A technique for forming an electrode by molding into an electrode is disclosed. According to the configuration of Patent Document 1, an electrode is laminated on a separator to form an electrode laminate, and a lithium ion secondary battery is configured using the electrode laminate, and a current collector such as a metal foil can be omitted. It is described that the weight can be reduced and the amount of the active material can be increased, so that the output of the lithium ion secondary battery can be increased.

JP-A-10-284055

  However, in the technique disclosed in Patent Document 1, since the electrodes are formed and pasted and bonded to the separator, the adhesion between the electrodes and the separator is poor, and the electrodes may peel from the separator. Further, in the technique disclosed in Patent Document 1, since the lead wire cannot be welded to the current collector plate as in the prior art, the adhesion between the electrode and the separator is poor, and when the electrode peels from the separator, the electrode and the lead The electrical connection with the wire is also insufficient, and there is a possibility that the expected performance as a battery cannot be exhibited. Therefore, the life of the lithium ion secondary battery could not be increased.

  As described above, in the conventionally proposed electrode formation technology, there is a problem of achieving both a long life and high output of the lithium ion secondary battery. That is, an object of the present invention is to provide a lithium ion secondary battery that can achieve both a long life and a high output.

  The lithium ion secondary battery of the present invention that solves the above problems is a lithium ion secondary battery having a structure in which an electrode capable of occluding and releasing lithium ions and a separator are laminated, the electrode comprising an active material and a conductive material. An electrode mixture coating layer formed by applying an electrode mixture in which fibers are dispersed and kneaded to the separator, and the electrode mixture coating layer and the separator are interposed between and electrically connected to the electrode mixture coating layer It is characterized by having a conducting wire.

  According to the lithium ion secondary battery of the present invention, since the electrode has the electrode mixture coating layer formed by coating the separator with an electrode mixture obtained by dispersing and kneading the active material and the conductive fiber. The current collection efficiency can be increased without using an electric body, the adhesion between the electrode mixture coating layer and the separator can be increased, and the electrode mixture coating layer can be prevented from peeling from the separator. .

  In addition, since a conducting wire is interposed between the electrode mixture coating layer and the separator and is electrically connected to the electrode mixture coating layer, conduction between the conducting wire and the electrode mixture coating layer must be ensured. It is possible to electrically connect between the electrode terminal such as a battery can or a battery lid and the conducting wire via the lead wire. Therefore, it is possible to provide a lithium ion secondary battery that can reliably exhibit the expected performance as a battery, can have a long life as a battery, and can achieve both a long life and high output.

The figure which shows the example of the electrode of the lithium ion secondary battery which concerns on embodiment of this invention. The figure which shows typically the cross-sectional structure along the AA 'line of FIG. The figure which shows one specific example of the electrode of the lithium ion secondary battery which concerns on Example 1 of this invention. FIG. 4 is a diagram schematically showing a cross-sectional structure along the line AA ′ in FIG. 3. The figure which shows the winding type lithium ion secondary battery which concerns on Example 1 of this invention in a single-sided cross section. The figure which shows one specific example of the electrode of the lithium ion secondary battery which concerns on Example 2 of this invention. The figure which shows typically the cross-sectional structure along the AA 'line of FIG. The figure which shows one specific example of the electrode of the lithium ion secondary battery which concerns on Example 3 of this invention. The figure which shows typically the cross-section along the AA 'line of FIG. The figure which shows one specific example of the electrode of the lithium ion secondary battery which concerns on Example 4 of this invention. The figure which shows one specific example of the electrode of the lithium ion secondary battery which concerns on Example 4 of this invention. The figure which shows the winding type lithium ion secondary battery which concerns on Example 6 of this invention in one side cross section. The figure which shows the winding type lithium ion secondary battery which concerns on Example 6 of this invention in one side cross section.

  Hereinafter, an electrode for a lithium ion secondary battery, a lithium ion secondary battery, and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings.

<Structure of electrode for lithium ion secondary battery>
FIG. 1 is a diagram illustrating an example of an electrode of a lithium ion secondary battery according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line AA ′ of FIG.

  The electrode 10 includes an electrode mixture coating layer 1 formed by applying an electrode mixture obtained by dispersing and kneading the active material 2 and the conductive fibers 3 to one surface of the first separator 4a, an electrode mixture coating layer 1, It has a metal wire (conductive wire) 5 interposed between the first separator 4 a and electrically connected to the electrode mixture coating layer 1.

  The electrode 10 is sandwiched between the first separator 4a and the second separator 4b. In the electrode 10, the electrode mixture is applied to the first separator 4 a to form the electrode mixture application layer 1, and the metal wire 5 is interposed between the first separator 4 a and the electrode mixture application layer 1. Yes.

  For example, as shown in FIG. 1A, the electrode mixture coating layer 1 has a certain area when the first separator 4a and the second separator 4b are formed of a strip-shaped sheet member that can be wound in a spiral shape. It is preferable that the electrode mixture is applied in a divided manner and is formed in each of a plurality of regions partitioned on the one surface of the first separator 4a at predetermined intervals in the longitudinal direction.

  The electrode mixture coating layer 1 is composed of an active material 2 and conductive fibers 3 as shown in FIG. 1B, which is an enlarged view of the B part in FIG. Although not carried out, a conductive agent, a binder resin, or the like may be added. The electrode mixture coating layer 1 has a different composition depending on whether the electrode 10 is a positive electrode or a negative electrode, as will be described later. Since the conductive fiber 3 has a role as a current collector, there is no need for a current collector such as a metal foil used in a conventional lithium ion secondary battery, the weight can be reduced, and the output of the battery is improved. be able to.

  The electrode mixture application layer 1 is formed by directly applying the electrode mixture to the first separator 4a and drying it. In the electrode mixture applied layer 1, two separators 4a and 4b are bonded to each other at the portion where the electrode mixture layer is not applied. The separator 4 is formed by stacking a second separator 4b on which the electrode mixture layer 1 is not applied on the first separator 4a, so that at least a portion of the first separator 4a and the second separator 4b facing each other. Partly combined. In the present embodiment, the first separator 4a and the second separator 4b are mutually attached at the electrode mixture uncoated portion so as to surround each electrode mixture coated layer 1 as indicated by a broken line in FIG. It is heat welded.

  The metal wire 5 is arranged along the longitudinal direction on one surface of the first separator 4a so as to extend over the region of the plurality of electrode mixture application layers 1, and the electrode mixture is applied thereon. Is done. Since the metal wire 5 is interposed between the electrode mixture coating layer 1 and the separator 4 and is electrically connected to the electrode mixture coating layer 1, the metal wire 5 and the electrode mixture coating layer 1 It is possible to reliably establish conduction between the two. Therefore, it becomes possible to electrically connect the electrode terminal such as a battery can or a battery lid of the lithium ion secondary battery and the metal wire 5 via a lead wire (not shown).

  The lithium ion secondary battery of the present invention is manufactured using the electrode 10 having the above-described configuration. For example, the electrode 10 forming the positive electrode and the negative electrode is spirally wound together with the separators 4a and 4b and inserted into the battery container, It is manufactured by dipping in an electrolytic solution in a battery container and sealing with a battery lid.

The material and manufacturing method of the lithium ion secondary battery according to the present invention will be described below.
<Negative electrode>
As the negative electrode active material, natural graphite, composite carbonaceous material in which a film formed by dry CVD (Chemical Vapor Dposition) method or wet spray method on natural graphite, resin raw material such as epoxy or phenol, petroleum or coal A carbonaceous material such as artificial graphite and amorphous carbon material produced by firing from a pitch-based material obtained from the above, or lithium metal that can occlude and release lithium by forming lithium and a compound, lithium and a compound An oxide or nitride of a Group 4 element such as silicon, germanium, or tin that can be formed and inserted into a crystal gap to occlude and release lithium can be used.

In some cases, these are generally referred to as negative electrode active materials. In particular, the carbonaceous material is a material having high conductivity, and excellent in terms of low temperature characteristics and cycle stability. Among the carbonaceous materials, a material having a wide carbon network surface layer (d ₀₀₂ ) is excellent in rapid charge / discharge and low temperature characteristics, and is suitable.

However, since a material having a wide carbon network surface layer (d ₀₀₂ ) may have a reduced capacity and low charge / discharge efficiency at the initial stage of charging, the carbon network surface layer (d ₀₀₂ ) is preferably 0.39 nm or less. Such a carbonaceous material may be referred to as pseudo-anisotropic carbon. Furthermore, in order to constitute the electrode 10, a carbonaceous material having high conductivity such as graphite, amorphous, activated carbon or the like may be mixed. Alternatively, a material having the characteristics shown in (1) to (3) below may be used as the graphite material.

(1) peak in the range of 1300～1400Cm ^-1 measured by Raman spectrum intensity (I _D) and the peak intensity in the range of 1580～1620Cm ^-1 as measured by Raman spectroscopy spectra (I _G) and the The R value (I _D / I _G ), which is an intensity ratio, is 0.2 or more and 0.4 or less. (2) The half-value width Δ value of a peak in the range of 1300 to 1400 cm ⁻¹ measured by a Raman spectroscopic spectrum is 40 cm ^-1 or more 100 cm ^-1 or less (3) the intensity ratio X values of the peak intensity of the (110) plane in X-ray diffraction (I ₍₁₁₀₎₎ and (004) plane peak intensity (I ₍₀₀₄₎₎ (I ₍₁₁₀₎ / I ₍₀₀₄₎ ) is 0.1 or more and 0.45 or less

  As the conductive fiber 3, various metals such as aluminum, copper, and stainless steel, and carbon fiber are used. The fiber diameter is preferably 5 to 200 μm and the fiber length is preferably 1 to 100 mm, and more preferably the fiber diameter is 5 to 100 μm and the fiber length is 7 to 30 mm. When the fiber diameter is thinner than this, it becomes difficult to give the electrode 10 sufficient strength, and when the fiber diameter is larger than this, not only the thin electrode 10 cannot be formed but also as a current collector. Efficiency is also reduced.

  The metal wire 5 may be made of various metals such as aluminum, copper, and stainless steel. It is desirable that the length is slightly longer than the first separator 4a and the second separator 4b.

  Further, a conductive agent may be further added to the negative electrode mixture layer in order to reduce electronic resistance. The conductive agent is, for example, a carbon material such as carbon black, graphite, carbon fiber, and metal carbide, and each may be used alone or in combination.

  A binder resin may be added in order to make the material constituting the negative electrode and the separator more closely contact each other. Examples thereof include homopolymers or copolymers such as vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, and styrene-butadiene rubber.

  As the solvent constituting the binder resin solution, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoamide, dioxane, tetrahydrofuran, tetramethyl Urea, triethyl phosphate, trimethyl phosphate, and the like can be used. In particular, nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, and N, N-dimethylacetamide are preferable because of high solubility of the binder resin. These solvents may be used alone or in combination.

  As the negative electrode drying conditions, the solvent constituting the binder resin solution evaporates and is preferably equal to or higher than the crystallization temperature of the binder and depends on the binder type and the solvent type. For example, in the case of PVDF, 150 ° C. is preferable.

<Positive electrode>
The positive electrode is formed by applying a positive electrode mixture composed of a positive electrode active material, conductive fibers, an electronic conductive material, and a binder on a separator. Further, a conductive agent may be added to the positive electrode mixture in order to reduce the electronic resistance. Further, a binder resin may be added in order to make the material constituting the positive electrode and the separator adhere more closely.

The positive electrode active material is a composition formula LiαMnxM1yM2zO ₂ (wherein M1 is at least one selected from Co and Ni, and M2 is at least one selected from Co, Ni, Al, B, Fe, Mg and Cr) X + y + z = 1, 0 <α <1.2, 0.2 ≦ x ≦ 0.6, 0.2 ≦ y ≦ 0.4, 0.05 ≦ z ≦ 0.4) Things are preferred. Among these, it is more preferable that M1 is Ni or Co and M2 is Co or Ni. LiMn _1/3 Ni _1/3 Co _1/3 O ₂ is more preferable.

  In the composition, if Ni is increased, the capacity can be increased, if Co is increased, the output at a low temperature can be improved, and if Mn is increased, the material cost can be suppressed. In addition, the additive element is effective in stabilizing the cycle characteristics.

In addition, the general formula LiMxPO ₄ (M: Fe or Mn, 0.01 ≦ X ≦ 0.4) and LiMn _1-x M _x PO ₄ (M: divalent cation other than Mn, 0.01 ≦ X ≦ An orthorhombic phosphate compound having symmetry of the space group Pmnb which is 0.4) may be used. In particular, LiMn _1/3 Ni _1/3 Co _1/3 O ₂ has high low-temperature characteristics and high cycle stability, and is suitable as a lithium battery material for hybrid vehicles (HEV).

  The binder may be any material as long as the material constituting the positive electrode and the separator are more closely adhered to each other. For example, a homopolymer or copolymer of vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, styrene-butadiene rubber, or the like. And so on.

  The conductive agent is, for example, a carbon material such as carbon black, graphite, carbon fiber, and metal carbide, and each may be used alone or in combination. The conductive fiber 3 is made of various metals such as aluminum, copper, and stainless steel, and carbon fiber as in the negative electrode.

  A binder resin may be added in order to make the material constituting the positive electrode and the separator more closely contact with each other. Examples thereof include homopolymers or copolymers such as vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, and styrene-butadiene rubber.

  The conductive agent is, for example, a carbon material such as carbon black, graphite, carbon fiber, and metal carbide, and each may be used alone or in combination. The metal wire 5 may be made of various metals such as aluminum, copper, and stainless steel like the negative electrode, and is preferably slightly longer than the separator.

<Electrolyte>
The electrolytic solution is composed of at least one compound selected from (Formula 1), (Formula 2), (Formula 3), and (Formula 4), and a lithium salt.

（式中、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄は、水素、フッ素、塩素、炭素数１〜３のアルキル基、フッ素化されたアルキル基のいずれかを表わす。）である。 The compound represented by (Formula 1) is

(Wherein R ₁ , R ₂ , R ₃ and R ₄ represent any one of hydrogen, fluorine, chlorine, an alkyl group having 1 to 3 carbon atoms, and a fluorinated alkyl group).

（式中、Ｒ₅、Ｒ₆は、水素、フッ素、塩素、炭素数１〜３のアルキル基、フッ素化されたアルキル基のいずれかを表わす。）である。 The compound represented by (Formula 2) is

(Wherein R ₅ and R ₆ represent any one of hydrogen, fluorine, chlorine, an alkyl group having 1 to 3 carbon atoms, and a fluorinated alkyl group).

（式中、Ｒ₇、Ｒ₈は、水素、フッ素、塩素、炭素数１〜３のアルキル基、フッ素化されたアルキル基のいずれかを表わす。）である。 The compound represented by (Formula 3) is

(Wherein R ₇ and R ₈ represent hydrogen, fluorine, chlorine, an alkyl group having 1 to 3 carbon atoms, or a fluorinated alkyl group).

（式中、Ｚ_１、Ｚ_２は、ビニル基、アクリル基、メタクリル基のいずれかを表わす。）である。 The compound represented by (Formula 4) is

(Wherein Z ₁ and Z ₂ represent any one of a vinyl group, an acrylic group and a methacryl group).

  The composition ratio of the compound represented by (Formula 1) with respect to the total volume of the solvent for the electrolyte solution composed of (Formula 1), (Formula 2), (Formula 3), and (Formula 4) 18.0 to 30.0 vol%, the composition ratio of the compound represented by (Formula 2) is 74.0 to 81.8 vol%, and the composition of the compound represented by (Formula 3) or (Formula 4) The ratio is 0.1 to 1.0 vol%. When the composition ratio of the compound represented by (Formula 3) or (Formula 4) is larger than 1.0 vol%, the internal resistance of the battery is increased, and the output of the battery is decreased.

  Examples of the compound represented by (Formula 1) include ethylene carbonate (EC), trifluoropropylene carbonate (TFPC), chloroethylene carbonate (ClEC), fluoroethylene carbonate (FEC), trifluoroethylene carbonate (TFEC), Fluoroethylene carbonate (DFEC), vinylethylene carbonate (VEC), etc. can be used.

  In particular, it is preferable to use EC from the viewpoint of film formation on the negative electrode. In addition, addition of a small amount (2 vol% or less) of ClEC, FEC, TFEC, or VEC is also involved in electrode film formation and provides good cycle characteristics. Furthermore, TFPC and DFEC may be used by adding a small amount (2 vol% or less) from the viewpoint of film formation on the positive electrode.

  Examples of the compound represented by (Formula 2) include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), and trifluoromethyl ethyl. Carbonate (TFMEC), 1,1,1-trifluoroethyl methyl carbonate (TFEMC), or the like can be used.

  DMC is a highly compatible solvent and is suitable for use in a mixture with EC or the like. DEC has a lower melting point than DMC and is suitable for low temperature (−30 ° C.) characteristics. EMC is suitable for low temperature characteristics because of its asymmetric molecular structure and low melting point. Since EPC and TFMEC have propylene side chains and an asymmetric molecular structure, they are suitable as adjusting solvents for low temperature characteristics. TFEMC fluorinates part of the molecule and has a large dipole moment, which is suitable for maintaining the dissociation property of the lithium salt at a low temperature, and is suitable for low temperature characteristics.

  As the compound represented by (Formula 3), vinylene carbonate (VC), methyl vinylene carbonate (MVC), dimethyl vinylene carbonate (DMVC), ethyl vinylene carbonate (EVC), diethyl vinylene carbonate (DEVC), or the like is used. Can do.

  VC has a low molecular weight and is considered to form a dense electrode film. MVC, DMVC, EVC, DEVC, and the like in which an alkyl group is substituted for VC are considered to form an electrode film having a low density in accordance with the size of the alkyl chain, and are considered to act effectively to improve low-temperature characteristics.

  Examples of the compound represented by (Formula 4) include dimethallyl carbonate (DMAC).

The lithium salt used in the electrolytic solution is not particularly limited. For inorganic lithium salts, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiI, LiCl, LiBr, etc., and for organic lithium salts, LiB [OCOCF ₃ ] ₄ LiB [OCOCF ₂ CF ₃ ] ₄ , LiPF ₄ (CF ₃ ) ₂ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ CF ₂ CF ₃ ) ₂ or the like can be used. In particular, LiPF ₆ frequently used in consumer batteries is a suitable material because of the stability of quality. LiB [OCOCF ₃ ] ₄ is an effective material because it has good dissociation and solubility and high conductivity at a low concentration.

<Separator>
As the separator related to the non-aqueous electrolyte secondary battery, a separator used in a known lithium ion secondary battery can be used, for example, a microporous film made of polyolefin such as polyethylene or polypropylene, or a nonwoven fabric. Can be mentioned. From the viewpoint of increasing the capacity of the battery, the thickness of the separator is preferably 20 μm or less, and more preferably 18 μm or less. By using a separator having such a thickness, the capacity per volume of the battery can be increased. However, if the separator is made too thin, the handleability is impaired, or the separation between the positive and negative electrodes is insufficient and short-circuiting is likely to occur, so the lower limit of the thickness is preferably 10 μm.

  In the lithium ion secondary battery having the above configuration, since the electrode mixture coating layer 1 is formed by directly applying the electrode mixture to the first separator 4a, the electrode mixture coating layer 1 and the first separator 4a are formed. Adhesion degree between is high. Further, the electrode mixture coating layer 1 is sandwiched between the first separator 4a and the second separator 4b, and at least a part of the first separator 4a and the second separator 4b facing each other. Is bonded to each other, so that the adhesion between the electrode mixture coating layer 1 and the first separator 4a can be improved, and the electrode mixture coating layer 1 can be prevented from being peeled off from the first separator 4a. Can do.

  Moreover, since the metal wire 5 is interposed between the electrode mixture coating layer 1 and the separator and is electrically connected to the electrode mixture coating layer 1, the metal wire 5 and the electrode mixture coating layer 1 Therefore, it is possible to reliably connect the electrode terminal such as a battery can or a battery lid and the metal wire 5 via the lead wire.

  Therefore, it is possible to provide a lithium ion secondary battery that can reliably exhibit the expected performance as a battery, can have a long life as a battery, and can achieve both a long life and high output.

In this way, a lithium-ion secondary battery that has both high contact and long life and high output can be provided, so it is widely used as a power source for hybrid vehicles, electric control systems for vehicles, and backup power sources that require high output. It can be used as a power source for industrial equipment such as railways, electric tools, and forklifts.
Examples of the present invention will be specifically described below.

Example 1
[Production of wound type battery]
The wound type battery of this example was manufactured by the method described below.
3 is a diagram showing a specific example of the electrode of the lithium ion secondary battery according to Example 1, FIG. 4 is a diagram schematically showing a cross-sectional structure along the line AA ′ of FIG. 3, and FIG. These are figures which show the winding type lithium ion secondary battery which concerns on Example 1 in one-side cross section.

  As shown in FIG. 5, the lithium ion secondary battery 101 includes an electrode winding group 21 that is formed by winding the electrode 10 and the separator 4 in a spiral shape in a state where the electrodes 10 and the separator 4 are overlapped with each other. The electrode winding group 21 is housed inside a bottomed cylindrical battery case 22. Then, an electrolytic solution made of a non-aqueous solvent is injected into the battery container 22, and the battery cover 23 is attached to the opening of the battery container 22 via an insulating gasket 26, so that the caulking is fixed.

  As shown in FIG. 3 and FIG. 4, the electrode winding group 21 includes a first separator 4a, a second separator 4b, a third separator 4c, and a third separator 4c and a second separator 4b. The positive electrode 12 is sandwiched, and the negative electrode 14 is sandwiched between the second separator 4b and the first separator 4a.

  The positive electrode 12 includes a positive electrode mixture application layer 11 formed by applying a positive electrode mixture obtained by dispersing and kneading a positive electrode active material and conductive fibers to the third separator 4c, and the positive electrode mixture application layer 11 and the third And a second metal wire (positive electrode conductor) 5b that is interposed between the separator 4c and electrically connected to the positive electrode mixture coating layer 11.

  The negative electrode 14 includes a negative electrode mixture coating layer 13 formed by applying a negative electrode mixture obtained by dispersing and kneading a negative electrode active material and conductive fibers to the first separator 4a, and a negative electrode mixture coating layer 13; A first metal wire (negative electrode conductor) 5a interposed between the first separator 4a and electrically connected to the negative electrode mixture coating layer 13;

The positive electrode 12 uses LiMn _1/3 Ni _1/3 Co _1/3 O ₂ as the positive electrode active material, carbon black (CB1) and graphite (GF2) as the electronic conductive material, and polyvinylidene fluoride (PVDF) as the binder. ), And the solid content weight at the time of drying is set to a ratio of LiMn _1/3 Ni _1/3 Co _1/3 O ₂ : CB1: GF2: PVDF: metal fiber = 80: 5: 5: 10 A positive electrode material paste was prepared using NMP (N-methylpyrrolidone) as a solvent.

  And the 2nd metal wire 5b was arrange | positioned to the mating surface of the 3rd separator 4c, and the positive electrode agent paste was apply | coated. An aluminum wire was used for the second metal wire 5b. As shown in FIG. 2, the positive electrode material paste is preferably applied by dividing the coating area into certain areas. Then, it dried at 80 degreeC, pressed with the pressure roller, and dried at 120 degreeC, and formed the positive mix application layer 11 in the 3rd separator 4c.

  The negative electrode 14 uses pseudo-anisotropic carbon, which is amorphous carbon, as the negative electrode active material, carbon black (CB2) as the conductive material, PVDF as the binder, carbon fiber as the conductive fiber, A negative electrode material slurry was prepared using NMP as a solvent so that the solid content weight ratio was pseudo-anisotropic carbon: CB2: PVDF: carbon fiber = 80: 5: 5: 10.

  And the 1st metal wire 5a was arrange | positioned on the mating surface of the 1st separator 4a, and the negative electrode material slurry was apply | coated. A copper wire was used for the first metal wire 5a. The negative electrode material slurry is preferably applied by dividing the application area into a certain area as shown in FIG. Thereafter, primary drying at 80 ° C., secondary drying at 150 ° C., pressing with a pressure roller, and drying at 150 ° C. formed the negative electrode mixture layer 13 on the first separator 4a.

As an electrolytic solution, a solvent is used as a volume composition ratio EC: VC: DMAC: DMC: EMC = 20: 0.
8: 0.2: 39.5: 39.5 was used, and 1M LiPF ₆ was dissolved as a lithium salt to prepare an electrolytic solution.

  Then, the third separator 4c and the second separator 4b are overlapped and bonded by heat welding or the like so that the positive electrode 12 is interposed therebetween, and then the second separator is interposed so that the negative electrode 14 is interposed therebetween. The separator 4b and the first separator 4a were overlapped and bonded by heat welding or the like. The positive electrode mixture coating layer 11 and the negative electrode mixture coating layer 13 are disposed at positions overlapping in the stacking direction, and the first metal line 5a and the second metal line 5b are disposed at positions aligned in the stacking direction. Each separator 4a, 4b, 4c was heat-welded with each other at the electrode mixture uncoated portion so as to surround the periphery of the positive electrode mixture coated layer 11 and the negative electrode mixture coated layer 13 as indicated by broken lines in FIG.

  Thereafter, an electrode winding group 21 was formed and inserted into the battery container 22. Then, one end of a nickel negative electrode lead 24 was welded to the first metal wire 5 a and the other end was welded to the battery container 22 in order to collect the negative electrode 14. Further, in order to collect the positive electrode 12, one end of the positive electrode lead 25 made of aluminum was welded to the second metal wire 5b, and the other end was welded to the battery lid 23 to be electrically connected.

[Battery characteristics evaluation]
<Method for evaluating battery capacity during storage at 50 ° C.>
The battery was charged at a constant current of 0.7 A to 4.1 V, charged at a constant voltage of 4.1 V until the current value reached 20 mA, and after 30 minutes of operation stop, discharged at 0.7 A to 2.7 V. This operation was repeated three times. Next, the battery was charged to 4.1 V at a constant current of 0.7 A, left for 30 minutes, placed in a 50 ° C. constant temperature bath, and the voltage after standing for 30 days was measured. The measurement results are shown in Table 1.

(Example 2)
6 is a diagram illustrating an example of an electrode of a lithium ion secondary battery according to Example 2, and FIG. 7 is a diagram schematically illustrating a cross-sectional structure along the line AA ′ of FIG. 6.

  The lithium ion secondary battery of Example 2 is different from Example 1 in the arrangement of the first metal wire 5a and the second metal wire 5b. A battery was produced in the same manner as in Example 1 except for the above. The first metal line 5a and the second metal line 5b are arranged at positions shifted from each other with respect to the stacking direction.

  For example, the first metal line 5a is arranged shifted from the width direction center of the separator 4 to one side in the width direction, and the second metal line 5b is arranged in the width direction opposite to the first metal line 5a from the width direction center. Shift to the other side. In the second embodiment, as shown in FIGS. 6 and 7, the first metal wire 5a is disposed on the A side, and the second metal wire 5b is disposed on the A ′ side. As long as the first metal line 5a does not overlap the second metal line 5b in the stacking direction as shown in FIG. 3, the arrangement is not limited. With such a configuration, the thickness of the electrode is reduced, more electrodes can be placed in the wound battery, and the capacity can be increased.

(Example 3)
FIG. 8 is a diagram illustrating an example of an electrode of a lithium ion secondary battery according to Example 3, and FIG. 9 is a diagram schematically illustrating a cross-sectional structure along the line AA ′ in FIG. 8. The arrangement of the first metal wire 5a and the second metal wire 5b and the electrode forming method are different from those in the first embodiment.

LiMn _1/3 Ni _1/3 Co _1/3 O ₂ is used as the positive electrode active material, carbon black (CB1) and graphite (GF2) are used as the electronic conductive material, and polyvinylidene fluoride (PVDF) is used as the binder. NMP as a solvent so that the solid content weight at the time of drying is a ratio of LiMn _1/3 Ni _1/3 Co _1/3 O ₂ : CB1: GF2: PVDF: metal fiber = 80: 5: 5: 10 A positive electrode material paste was prepared using (N-methylpyrrolidone). This positive electrode material paste was applied to the third separator 4c, dried at 80 ° C., pressed with a pressure roller, and dried at 120 ° C. to form the positive electrode mixture coating layer 11 on the third separator 4c. In addition, as shown in FIG. 8, it is desirable to divide and apply | coat an application area for every fixed area.

  Next, pseudo-anisotropic carbon, which is amorphous carbon, is used as the negative electrode active material, carbon black (CB2) is used as the conductive material, PVDF is used as the binder, carbon fibers are used as the conductive fibers, and the solids are dried. A negative electrode material slurry was prepared using NMP as a solvent so that the partial weight was a ratio of pseudo anisotropic carbon: CB2: PVDF: carbon fiber = 80: 5: 5: 10.

  This negative electrode material slurry was applied to the first separator 4a. In addition, as shown in FIG. 8, it is desirable to divide and apply | coat an application area for every fixed area. Thereafter, primary drying at 80 ° C., secondary drying at 150 ° C., pressing with a pressure roller, and drying at 150 ° C. formed the negative electrode mixture layer 13 on the first separator 4a.

As an electrolytic solution, a solvent is used as a volume composition ratio EC: VC: DMAC: DMC: EMC = 20: 0.
A mixture of 8: 0.2: 39.5: 39.5 was used, and 1M LiPF ₆ was used as a lithium salt.
It melt | dissolved and produced electrolyte solution.

  And the negative electrode mixture layer 13 side of the 1st separator 4a and the 2nd separator 4b were piled up, and the part to which the negative electrode mixture of the 1st separator 4a did not adhere was connected by heat welding etc. At that time, the first metal wire 5a is sandwiched between the negative electrode mixture layer 13 and the second separator 4b. A copper wire was used as the first metal wire.

  Next, the first separator 4 a and the second separator 4 b connected to the third separator 4 c coated with the positive electrode mixture coating layer 11 are combined. At that time, the second metal wire 5b is sandwiched between the positive electrode mixture coating layer 11 and the third separator 4c. An aluminum wire was used as the second metal wire 5b. The surface of the second separator 4b on which the negative electrode mixture layer 13 is not applied and the surface of the third separator 4c on which the positive electrode mixture coating layer 11 is applied are aligned and connected by thermal welding or the like. Group 21 was formed and inserted into battery container 22. Then, one end of a nickel negative electrode lead 24 was welded to the first metal wire 5 a and the other end was welded to the battery container 22 in order to collect the negative electrode 14. Further, in order to collect the positive electrode 12, one end of the positive electrode lead 25 made of aluminum was welded to the second metal wire 5b, and the other end was welded to the battery lid 23 to be electrically connected.

  As in the second embodiment, the first metal line 5a is arranged so as to be shifted from the center in the width direction of the separator 4 to one side in the width direction, and the second metal line 5b is arranged from the center in the width direction of the separator 4 to the first metal. It is shifted to the opposite side to the line 5a. For example, as shown in FIGS. 8 and 9, the first metal line 5a is disposed on the A side, and the second metal line 5b is disposed on the A 'side. As long as the first metal line 5a does not overlap the second metal line 5b as shown in FIG. 3, the arrangement is not limited.

  A battery was produced in the same manner as in Example 1 except for the above. By adopting such a configuration, the unevenness of the winding group due to the metal wire arrangement is reduced, the thickness of the electrode is reduced, more electrodes can be put in the winding type battery, and the capacity can be increased. Become.

Example 4
10 and 11 are diagrams showing a specific example of an electrode of a lithium ion secondary battery according to Example 4 of the present invention, and schematically show a cross-sectional structure along the line AA ′ of FIG. Is. The first metal wire 5a and the second metal wire 5b are different in cross section from the first embodiment. A battery was produced in the same manner as in Example 1 except for the above.

  As shown in FIG. 10, a metal wire having a flat cross section is used. For example, a metal foil such as copper or aluminum may be used, or a metal wire used in Example 1 may be pressed with a press machine or the like.

  By using a metal wire with a flat cross section, the irregularities of the wound group due to the metal wire arrangement are reduced, and the thickness of the electrode is further reduced. Therefore, more electrodes can be put in the wound battery, and the capacity can be further increased.

  Further, as shown in FIG. 11, the first metal wire 5a may be arranged on the A side and the second metal wire 5b may be arranged on the A ′ side as in the second embodiment. The unevenness is further reduced, and the thickness of the electrode is further reduced. Therefore, more electrodes can be put in the wound battery, and the capacity can be further increased.

  As long as the first metal wire 5a does not overlap the second metal wire 5b in the thickness direction as shown in FIG. 3, the arrangement is not limited.

(Example 5)
FIG. 12 is a diagram showing a wound-type lithium ion secondary battery according to Example 5 of the present invention in a cross section on one side.

  What is characteristic in Example 5 is that, of the positive electrode 12 and the negative electrode 14, only the negative electrode 14 is formed by applying the negative electrode mixture to the characteristic configuration of the present invention, that is, the first separator 4a. A negative electrode mixture coating layer 13, and a metal wire 5 interposed between the negative electrode mixture coating layer 13 and the first separator 4 a and electrically connected to the negative electrode mixture coating layer 13. 12 has a configuration in which the positive electrode mixture coating layer 11 is formed on the positive electrode current collector 15 by using the positive electrode current collector 15 as in the prior art.

LiMn _1/3 Ni _1/3 Co _1/3 O ₂ is used as the positive electrode active material, carbon black (CB1) and graphite (GF2) are used as the electronic conductive material, and polyvinylidene fluoride (PVDF) is used as the binder. The solid weight at the time of drying was set to NMP (N-- as a solvent so that the ratio of LiMn _1/3 Ni _1/3 Co _1/3 O ₂ : CB1: GF2: PVDF = 86: 9: 2: 3 A positive electrode material paste was prepared using methylpyrrolidone). This positive electrode material paste is applied to an aluminum foil to be the positive electrode current collector 15, dried at 80 ° C., pressed with a pressure roller, and dried at 120 ° C. to form the positive electrode mixture applied layer 11 on the positive electrode current collector 15. did.

  Further, in order to collect the current of the positive electrode 12, one end of the positive electrode lead 25 made of aluminum was welded to the positive electrode current collector 15, and the other end was welded to the battery lid 23 to be electrically connected. Further, a wound battery 101 was manufactured by injecting and caulking an electrolytic solution. A battery was produced in the same manner as in Example 1 except for the above.

(Example 6)
FIG. 13: is a figure which shows the winding type lithium ion secondary battery which concerns on Example 6 of this invention in a single-sided cross section.

  What is characteristic in Example 6 is that, of the positive electrode 12 and the negative electrode 14, only the positive electrode 12 is formed by applying the positive electrode mixture to the characteristic configuration of the present invention, that is, the third separator 4c. A positive electrode mixture coating layer 11, and a metal wire 5 interposed between the positive electrode mixture coating layer 11 and the third separator 4 c and electrically connected to the positive electrode mixture coating layer 11. No. 14 has a configuration in which the negative electrode current collector 16 is used and the negative electrode current collector coating layer 13 is formed on the negative electrode current collector 16 as in the prior art.

  Using pseudo-anisotropic carbon, which is amorphous carbon, as the negative electrode active material, using carbon black (CB2) as the conductive material, using PVDF as the binder, the solid content weight at the time of drying is determined as pseudo-anisotropic carbon: A negative electrode material slurry was prepared using NMP as a solvent so that the ratio of CB2: PVDF = 88: 4: 8. This negative electrode material slurry is applied to a copper foil to be the negative electrode current collector 16, primary dried at 80 ° C., then secondary dried at 150 ° C., pressed with a pressure roller, and dried at 150 ° C. to form a negative electrode mixture The layer 13 was formed on the negative electrode current collector 16.

  Then, one end of a nickel negative electrode lead 24 was welded to the negative electrode current collector 16 and the other end was welded to the battery container 22 in order to collect the current of the negative electrode 14. A battery was produced in the same manner as in Example 1 except for the above.

(Comparative Example 1)
The lithium ion secondary battery of Comparative Example 1 has a negative electrode current collector and a positive electrode current collector. The positive electrode slurry adjustment, application, and current collection were formed by the method of Example 2, and the negative electrode slurry adjustment, application, and current collection were formed by the method of Example 3. A battery was produced in the same manner as in Example 1 except for the above. The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Electrode mixture application layer 2 Active material 3 Conductive fiber 4 Separator 4a 1st separator 4b 2nd separator 4c 3rd separator 5 Metal wire (conductor)
5a First metal wire (conductor)
5b Second metal wire (conductor)
DESCRIPTION OF SYMBOLS 10 Electrode 11 Positive electrode mixture coating layer 12 Positive electrode 13 Negative electrode mixture coating layer 14 Negative electrode 15 Positive electrode collector 16 Negative electrode collector 21 Electrode winding group 22 Battery container 23 Battery lid 24 Negative electrode lead 25 Positive electrode lead

Claims (4)

A lithium ion secondary battery having a structure in which an electrode capable of inserting and extracting lithium ions and a separator are laminated,
The electrode is
An electrode mixture coating layer formed by applying an electrode mixture obtained by dispersing and kneading an active material and conductive fibers to the separator;
A conductive wire interposed between the electrode mixture coating layer and the separator and electrically connected to the electrode mixture coating layer;
The separator is formed of a belt-like sheet member that can be wound in a spiral shape, and includes a first separator and a second separator that sandwich the electrode, and each of the separators is coupled to at least a part of a portion facing each other. Has been
In the electrode, the electrode mixture is applied to the first separator to form the electrode mixture application layer, and the conductive wire is interposed between the first separator and the electrode mixture application layer. And
The electrode mixture coating layer is formed in each of a plurality of regions partitioned at a predetermined interval in the longitudinal direction of the separator on one side of the separator,
The said conducting wire is arrange | positioned so that it may extend over the said several area | region, The lithium ion secondary battery characterized by the above-mentioned. A lithium ion secondary battery having a structure in which an electrode capable of inserting and extracting lithium ions and a separator are laminated,
The electrode is
An electrode mixture coating layer formed by applying an electrode mixture obtained by dispersing and kneading an active material and conductive fibers to the separator;
A conductive wire interposed between the electrode mixture coating layer and the separator and electrically connected to the electrode mixture coating layer;
Have
The separator comprises a first separator, the second separator stacked on the first separator, a third separator stacked on the second separator,
The electrode includes a positive electrode sandwiched between the third separator and the second separator, and a negative electrode sandwiched between the first separator and the second separator,
The positive electrode comprises a positive electrode mixture coating layer formed by applying a positive electrode mixture obtained by dispersing and kneading an active material made of a lithium-containing composite and conductive fibers to the third separator; and the positive electrode mixture coating layer And a positive electrode lead wire interposed between the third separator and electrically connected to the positive electrode mixture coating layer,
The negative electrode comprises a negative electrode mixture coating layer formed by applying a negative electrode mixture obtained by dispersing and kneading an active material made of a material capable of holding lithium and conductive fibers to the first separator, and the negative electrode mixture. A lithium ion secondary battery comprising: a negative electrode conductive wire interposed between the agent coating layer and the first separator and electrically connected to the negative electrode mixture coating layer. A lithium ion secondary battery having a structure in which an electrode capable of inserting and extracting lithium ions and a separator are laminated,
The electrode is
An electrode mixture coating layer formed by applying an electrode mixture obtained by dispersing and kneading an active material and conductive fibers to the separator;
A conductive wire interposed between the electrode mixture coating layer and the separator and electrically connected to the electrode mixture coating layer;
Have
The separator comprises a first separator, the second separator stacked on the first separator, a third separator stacked on the second separator,
The electrode includes a positive electrode sandwiched between the third separator and the second separator, and a negative electrode sandwiched between the second separator and the first separator,
The positive electrode comprises a positive electrode mixture coating layer formed by applying a positive electrode mixture obtained by dispersing and kneading an active material made of a lithium-containing composite and conductive fibers to the third separator; and the positive electrode mixture coating layer And a positive electrode lead wire interposed between the second separator and electrically connected to the positive electrode mixture coating layer,
The negative electrode comprises a negative electrode mixture coating layer formed by applying a negative electrode mixture obtained by dispersing and kneading an active material made of a material capable of holding lithium and conductive fibers to the first separator, and the negative electrode mixture. A lithium ion secondary battery comprising: a negative electrode conductive wire interposed between the agent coating layer and the second separator and electrically connected to the negative electrode mixture coating layer.   4. The lithium ion secondary battery according to claim 2, wherein the positive electrode conducting wire and the negative electrode conducting wire are arranged at positions shifted from each other in the stacking direction. 5.

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