WO2011070710A1 - Batterie secondaire à électrolyte non aqueux - Google Patents

Batterie secondaire à électrolyte non aqueux Download PDF

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Publication number
WO2011070710A1
WO2011070710A1 PCT/JP2010/006405 JP2010006405W WO2011070710A1 WO 2011070710 A1 WO2011070710 A1 WO 2011070710A1 JP 2010006405 W JP2010006405 W JP 2010006405W WO 2011070710 A1 WO2011070710 A1 WO 2011070710A1
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negative electrode
thin film
electrolyte secondary
secondary battery
positive electrode
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PCT/JP2010/006405
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English (en)
Japanese (ja)
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佐藤俊忠
渡邉耕三
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パナソニック株式会社
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Priority to US13/147,520 priority Critical patent/US20110287297A1/en
Priority to CN2010800044777A priority patent/CN102282698A/zh
Priority to JP2011513564A priority patent/JPWO2011070710A1/ja
Publication of WO2011070710A1 publication Critical patent/WO2011070710A1/fr

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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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • 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
    • 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.
  • the nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a separator.
  • a material that reversibly electrochemically reacts with lithium ions positive electrode active material, lithium-containing composite oxide
  • positive electrode active material positive electrode active material, lithium-containing composite oxide
  • negative electrode active material such as graphite or tin alloy
  • the separator is interposed between the positive electrode and the negative electrode, prevents a short circuit from occurring between the positive electrode and the negative electrode, and holds the electrolytic solution.
  • a lithium salt for example, LiClO 4 or LiPF 6
  • an aprotic organic solvent for example, LiClO 4 or LiPF 6
  • Non-aqueous electrolyte secondary battery is manufactured according to the following method. First, each of the positive electrode and the negative electrode is formed into a thin film sheet or a foil shape, and the positive electrode and the negative electrode are laminated or wound in a spiral shape via a separator.
  • the electrode group thus produced is housed in a battery case (may be made of metal such as iron, aluminum or stainless steel, or nickel plating or the like may be applied to the case surface)
  • a non-aqueous electrolyte is injected into the battery case. Then, the opening part of a battery case is sealed with a cover plate.
  • An aluminum laminate film may be used instead of the metal battery case.
  • a foreign substance made of metal may be mixed.
  • a metal foreign object a metal mixed during synthesis of a positive electrode active material or a conductive agent, or a rotating part such as a bearing or a roller in a manufacturing apparatus wears during manufacturing of a nonaqueous electrolyte secondary battery.
  • produces by can be mentioned. Therefore, examples of the metal foreign material include iron, nickel, copper, stainless steel, and brass.
  • the present invention has been made in view of such a point, and an object thereof is to provide a nonaqueous electrolyte secondary battery in which safety is guaranteed.
  • the positive electrode, the negative electrode, the separator, and the non-aqueous electrolyte are accommodated in the battery case.
  • the separator has a main layer and a plurality of thin films.
  • Each of the plurality of thin films has a film thickness thinner than that of the main layer, and has an ion transmittance smaller than that of the main layer.
  • the plurality of thin films have different ion transmittances.
  • foreign metal ions can be prevented from passing through each thin film in the thickness direction. Therefore, it can prevent that a metal foreign material ion reaches
  • a thin film having the smallest ion permeability among a plurality of thin films is provided on the surface of the negative electrode, and a thin film having the smallest ion permeability among the plurality of thin films. Is more preferably adhered to the surface of the negative electrode. Thereby, it can suppress that a metal foreign material ion reaches
  • the plurality of thin films are arranged such that the ion transmittance decreases from the positive electrode toward the negative electrode.
  • transmitted in the thickness direction of an electrode group can be gradually reduced as it goes to a negative electrode from a positive electrode.
  • a thin film having the largest ion permeability among a plurality of thin films may be integrated with the main layer.
  • a plurality of thin films have different hexafluoropropylene concentrations, and a thin film having a high hexafluoropropylene concentration has a larger ion permeability than a thin film having a low hexafluoropropylene concentration.
  • each thin film may contain a copolymer of hexafluoropropylene and vinylidene fluoride, and the thin film having the smallest ion permeability among the plurality of thin films may be made of polyvinylidene fluoride.
  • the positive electrode only needs to have a composite oxide containing lithium, a first metal (metal other than lithium), and oxygen.
  • X / y is preferably larger than 1.05 when the total number of moles is x [mol] and the total number of moles of the first metal in the composite oxide is y [mol].
  • multiple thin films includes a case where the boundary between thin films cannot be confirmed. For example, when thin films having a very small thickness are stacked, it may be difficult to confirm the boundary between the thin films.
  • the “ion transmittance” can be measured, for example, according to the following method.
  • an electrolyte solution (A) containing a metal salt is placed on one side with a predetermined membrane (a membrane for measuring ion permeability), and a solution (B) containing no metal salt is placed on the other side.
  • the salt concentration in the solution (B) is measured.
  • the ionic conductivity of the solution (B) is measured, and a previously prepared calibration curve showing the relationship between the salt concentration and the ionic conductivity is used in the solution (B). Estimate the salt concentration.
  • ion of “ion transmittance” is a cation in the nonaqueous electrolyte, and includes not only foreign metal ions but also lithium ions.
  • the thin film is integral with the main layer
  • the boundary between the thin film and the main layer cannot be clearly confirmed.
  • a part of the material constituting the thin film penetrates into the main layer. That is.
  • the thin film may be integrated with the main layer.
  • the “surface of the positive electrode” is a surface of both surfaces of the positive electrode facing the positive electrode and the negative electrode that transfers lithium ions
  • the “surface of the negative electrode” is the negative electrode and lithium ions of both surfaces of the negative electrode. This is the surface facing the positive electrode that receives and delivers.
  • FIG. 1 (a) to 1 (c) are cross-sectional views illustrating a state in which metal foreign matter is deposited on the surface of the negative electrode.
  • FIG. 2 is a longitudinal sectional view of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention.
  • FIG. 3 is a cross-sectional view of an electrode group in one embodiment of the present invention.
  • FIG. 4 is a cross-sectional view illustrating how the foreign metal ions move in the separator in one embodiment of the present invention.
  • FIG. 5 is a table summarizing the results of Example 1.
  • FIG. 6 is a table summarizing the results of Example 2.
  • FIG. 7 is a table summarizing the results of Example 3.
  • FIGS. 1A to 1C are cross-sectional views illustrating a state in which metal foreign matter is deposited on the surface of the negative electrode.
  • the thickness of the separator 96 is shown larger than the thickness of each of the positive electrode 94 and the negative electrode 95, and FIGS.
  • the relationship between the film thicknesses of the positive electrode 94, the negative electrode 95, and the separator 96 shown is different from the relationship between the film thicknesses of the positive electrode, the negative electrode, and the separator in an actual nonaqueous electrolyte secondary battery.
  • the metal foreign matter (X) in the positive electrode 94 (especially the positive electrode active material), the metal foreign matter generated during the production of the nonaqueous electrolyte secondary battery, or the metal foreign matter generated due to wear is under the immersion potential of the positive electrode (the immersion potential is Or an ion (X n + ) that dissolves under the operating potential of the positive electrode and moves, for example, in the separator 96 toward the surface of the negative electrode 95 during charging.
  • the negative electrode 95 is equal to or lower than the deposition potential of the metal foreign matter, the metal foreign matter ions are deposited on the surface of the negative electrode 95 located at the shortest distance as shown in FIG.
  • FIG. 2 is a longitudinal sectional view of the nonaqueous electrolyte secondary battery according to the present embodiment.
  • FIG. 3 is a cross-sectional view of the electrode group in the present embodiment.
  • the nonaqueous electrolyte secondary battery according to the present embodiment includes, for example, a stainless steel battery case 1 and an electrode group 8 accommodated in the battery case 1 as shown in FIG. In addition, a nonaqueous electrolyte is injected into the battery case 1.
  • An opening 1 a is formed on the upper surface of the battery case 1.
  • a sealing plate 2 is caulked to the opening 1a via a gasket 3, whereby the opening 1a is sealed.
  • the electrode group 8 includes a positive electrode 4, a negative electrode 5, and a separator 6, and the positive electrode 4 and the negative electrode 5 are wound in a spiral shape via the separator 6 as shown in FIG. 3.
  • An upper insulating plate 7 a is disposed above the electrode group 8, and a lower insulating plate 7 b is disposed below the electrode group 8.
  • One end of a positive electrode lead 4L made of aluminum is attached to the positive electrode 4, and the other end of the positive electrode lead 4L is connected to a sealing plate 2 (also serving as a positive electrode terminal).
  • One end of a negative electrode lead 5L made of nickel is attached to the negative electrode 5, and the other end of the negative electrode lead 5L is connected to the battery case 1 (also serving as a negative electrode terminal).
  • the positive electrode 4 has a positive electrode current collector 4A and a positive electrode mixture layer 4B.
  • the positive electrode current collector 4A is a conductive plate-like member, and is made of, for example, aluminum.
  • the positive electrode mixture layer 4B is provided on both surfaces of the positive electrode current collector 4A, and is bonded to a positive electrode active material (a composite oxide containing lithium and a metal other than lithium (first metal) and oxygen, for example, LiCoO 2 ). It contains an adhesive and a conductive agent.
  • the negative electrode 5 has a negative electrode current collector 5A and a negative electrode active material layer 5B.
  • the negative electrode current collector 5A is a conductive plate-like member, and is made of, for example, copper.
  • the negative electrode active material layer 5B is provided on both surfaces of the negative electrode current collector 5A, and may contain a graphite material and a binder. Silicon, tin, a compound containing silicon, or a compound containing tin (hereinafter referred to as “tin”) Then, it is described as “metal or a compound containing a metal”).
  • the separator 6 holds a non-aqueous electrolyte, and is provided between the positive electrode 4 and the negative electrode 5 as shown in FIG.
  • the separator 6 has a main layer 6A, a first thin film 6B, and a second thin film 6C.
  • the main layer 6 ⁇ / b> A is provided on the surface of the positive electrode 4.
  • the main layer 6A has a high ion permeability and a predetermined mechanical strength and insulation, and is, for example, a microporous film, a woven fabric or a non-woven fabric made of polyolefin such as polypropylene or polyethylene.
  • the second thin film 6 ⁇ / b> C is provided on the surface of the negative electrode 5 and is preferably bonded to the surface of the negative electrode 5.
  • the first thin film 6B is sandwiched between the main layer 6A and the second thin film 6C, is preferably integral with the main layer 6A, and is preferably bonded to the second thin film 6C.
  • the electrode group 8 having such a separator 6 is produced according to any of the following methods.
  • the first method the second thin film 6C and the first thin film 6B are sequentially formed on the surface of the negative electrode 5, and then the main layer 6A and the first thin film 6B formed on the surface of the positive electrode 4 are formed. Wind them after bringing them into contact with each other.
  • the second method the main layer 6A, the first thin film 6B, and the second thin film 6C are sequentially formed on the surface of the positive electrode 4, and then the second thin film 6C is brought into contact with the surface of the negative electrode 5. Turn around.
  • the first thin film 6B and the second thin film 6C are sequentially formed on the surface of the carrier (the surface of the carrier is subjected to a release treatment) and then the main body on the surface of the positive electrode 4
  • the first thin film 6B is peeled off from the carrier, and the first thin film 6B and the second thin film 6C are sandwiched between the main layer 6A and the negative electrode 5, and then the film is placed between the layer 6A and the negative electrode 5.
  • the separator 6 in this embodiment is further shown.
  • the main layer 6A has a larger film thickness than each of the first thin film 6B and the second thin film 6C.
  • the thickness of the main layer 6A is, for example, 10 ⁇ m or more and 300 ⁇ m or less, preferably 10 ⁇ m or more and 40 ⁇ m or less, more preferably 15 ⁇ m or more and 30 ⁇ m or less, and most preferably 15 ⁇ m or more and 25 ⁇ m or less.
  • the total thickness of the first thin film 6B and the second thin film 6C is, for example, 0.01 ⁇ m or more and 20 ⁇ m or less, preferably 0.1 ⁇ m or more and 15 ⁇ m or less, and preferably 0.5 ⁇ m or more and 10 ⁇ m or less. More preferably.
  • the thickness of the main layer 6A is less than 10 ⁇ m, a sufficient amount of nonaqueous electrolyte may not be retained. In addition, contact between the positive electrode 4 and the negative electrode 5 may not be avoided, and thus an internal short circuit may occur. On the other hand, if the thickness of the main layer 6 ⁇ / b> A exceeds 300 ⁇ m, the occupation ratio of the separator 6 in the electrode group 8 becomes high, so that a sufficient amount of active material may not be filled in the battery case 1.
  • the sum of the film thickness of the first thin film 6B and the film thickness of the second thin film 6C is less than 0.01 ⁇ m, it may not be possible to prevent the occurrence of an internal short circuit due to the mixing of metal foreign matter.
  • the total thickness of the first thin film 6B and the second thin film 6C exceeds 20 ⁇ m, the occupation ratio of the first thin film 6B and the second thin film 6C in the separator 6 increases. In some cases, the function of the separator 6 may be reduced. In addition, the diffusion of lithium ions in the separator 6 may be suppressed, which may cause a decrease in battery performance.
  • the sum of the thickness of the first thin film 6B and the thickness of the second thin film 6C may be 0.1% or more of the thickness of the main layer 6A, and is 0.1% or more and 20%. Or less, more preferably 0.1% or more and 10% or less. If the sum of the film thickness of the first thin film 6B and the film thickness of the second thin film 6C is less than 0.1% of the thickness of the main layer 6A, it is impossible to prevent the occurrence of an internal short circuit due to the mixing of metal foreign matter. There is a case. On the other hand, if the total thickness of the first thin film 6B and the second thin film 6C exceeds 20% of the thickness of the main layer 6A, the function of the separator 6 may be deteriorated. In addition, the diffusion of lithium ions in the separator 6 may be suppressed, which may cause a decrease in battery performance.
  • the main layer 6A, the first thin film 6B, and the second thin film 6C have different ion transmittances.
  • the main layer 6A has the maximum ion transmittance, and the ion transmittance decreases in the order of the first thin film 6B and the second thin film 6C. Thereby, it is possible to prevent the occurrence of an internal short circuit due to the mixing of metal foreign matter.
  • FIG. FIG. 4 is a cross-sectional view illustrating how the foreign metal ions move in the separator 6 in the present embodiment. In FIG.
  • the thickness of the separator 6 is shown larger than the thickness of each of the positive electrode 4 and the negative electrode 5, and the relationship between the thickness of the positive electrode 4, the negative electrode 5 and the separator 6 shown in FIG. Is different from the relationship of the film thicknesses of the positive electrode 4, the negative electrode 5, and the separator 6 in an actual nonaqueous electrolyte secondary battery.
  • the metal foreign matter mixed in the positive electrode mixture layer 4B When attention is paid to the metal foreign matter mixed in the positive electrode mixture layer 4B, the metal foreign matter is dissolved as a metal ion in the nonaqueous electrolyte under the immersion potential of the positive electrode 4 or the operating potential of the positive electrode 4, for example, charging It moves toward the negative electrode 5 inside.
  • the separator 6 the main layer 6 ⁇ / b> A, the first thin film 6 ⁇ / b> B, and the second thin film 6 ⁇ / b> C are arranged in order from the positive electrode 4 to the negative electrode 5. For this reason, the foreign metal ions pass through the main layer 6A and arrive at the first thin film 6B.
  • the first thin film 6B Since the first thin film 6B has an ion transmittance lower than that of the main layer 6A, some of the foreign metal ions arriving at the first thin film 6B cannot pass through the first thin film 6B, and the first thin film 6B does not pass through the first thin film 6B. It diffuses into the thin film 6B (the foreign metal ions on the left side of FIG. 4).
  • the foreign metal ions transmitted through the first thin film 6B arrive at the second thin film 6C. Since the second thin film 6C has an ion transmission rate lower than that of the first thin film 6B, it is difficult for the foreign metal ions reaching the second thin film 6C to pass through the second thin film 6C. In the thin film 6C (metal foreign ion on the right side in FIG. 4). Thereby, it is possible to delay the arrival of the metal foreign matter ions to the surface of the negative electrode 5.
  • Metal foreign matter generated during the manufacture of the nonaqueous electrolyte secondary battery or metal foreign matter caused by wear is not necessarily mixed in the positive electrode 4, and may be mixed in the main layer 6A, for example. Regardless of the position where the metal foreign matter is mixed, the metal foreign matter ions diffuse into the first thin film 6B or the second thin film 6C. Therefore, in the present embodiment, it is possible to prevent the occurrence of an internal short circuit regardless of the cause of occurrence of the metallic foreign matter.
  • the amount of the foreign metal ions that have passed through the second thin film 6C can be kept low. Therefore, the amount of metallic foreign matter deposited on the surface of the negative electrode 5 can be reduced.
  • the foreign metal ions transmitted through the second thin film 6C reach the surface of the negative electrode 5 after being slightly diffused in the first thin film 6B and the second thin film 6C. Therefore, it is possible to prevent the metal foreign matter from being deposited in a direction perpendicular to the surface of the negative electrode 5. From these things, in this embodiment, even if it is a case where a metal foreign material precipitates on the surface of the negative electrode 5, generation
  • the nonaqueous electrolyte secondary battery according to this embodiment has no problem in the operation of the battery.
  • Each structure of the 1st thin film 6B and the 2nd thin film 6C is further demonstrated.
  • the first thin film 6B and the second thin film 6C have different ion transmittances.
  • the first thin film 6B is preferably bonded to the surfaces of the main layer 6A and the second thin film 6C, and the second thin film 6C is preferably bonded to the surface of the negative electrode 5. From these things, the 1st thin film 6B should just contain the material which can adjust ion transmittance, and the material which has adhesiveness.
  • the second thin film 6C may include a material capable of adjusting the ion permeability and a material having an adhesive ability, or may be made of a material having an adhesive ability.
  • HFP hexafluoropropylene
  • PVDF poly (vinylidene fluoride)
  • HFP is more flexible than poly (vinylidene fluoride) (hereinafter referred to as “PVDF”) and so on, so that it takes in an electrolyte and swells. Therefore, HFP is excellent in affinity with the non-aqueous electrolyte. Therefore, if the concentration of HFP in the membrane is increased, the ion permeability of the membrane can be increased. Therefore, it is sufficient that the HFP concentration in the first thin film 6B is higher than the HFP concentration in the second thin film 6C.
  • the HFP concentration in the first thin film 6B is 2% by mass or more and 30% by mass or less
  • the HFP concentration in the second thin film 6C is 0% by mass or more and 20% by mass or less. If the HFP concentration in the first thin film 6B is less than 2% by mass, and if the HFP concentration in the second thin film 6C exceeds 20% by mass, the first thin film 6B and the second thin film 6C Difficult to make difference in ion permeability. On the other hand, if the HFP concentration in the first thin film 6B exceeds 30% by mass, the first thin film 6B is likely to swell the nonaqueous electrolyte. Therefore, the main layer 6A, the second thin film 6C, and the first thin film It causes a decrease in adhesive strength with 6B.
  • PVDF polytetrafluoroethylene
  • aramid resin polyamide
  • polyimide polyimide
  • PVDF is excellent in adhesive strength. Therefore, it is possible to prevent the first thin film 6B from being peeled off from the surface of the main layer 6A or the surface of the second thin film 6C during the production of the electrode group 8, and the second thin film 6C is the surface of the first thin film 6B. Alternatively, peeling from the surface of the negative electrode 5 can be prevented.
  • PVDF is excellent in flexibility. Therefore, each of the first thin film 6B and the second thin film 6C is deformed following the expansion or contraction of the negative electrode active material. Therefore, the nonaqueous electrolyte secondary battery can be charged / discharged without lowering the performance and safety, and the cycle characteristics can be prevented from lowering. This effect is increased when a metal or a compound containing a metal is used for the negative electrode active material. This is because, when the negative electrode active material is a metal or a compound containing a metal, the amount of expansion and contraction of the negative electrode active material due to charge / discharge is larger than when the negative electrode active material is a carbon material. This is because the amount of deformation of the first thin film 6B and the second thin film 6C due to the expansion and contraction of the active material increases.
  • PVDF is electrically stable in the voltage range where the non-aqueous electrolyte secondary battery operates, and does not react with the non-aqueous electrolyte.
  • the first thin film 6B preferably contains 2% by mass or more and 30% by mass or less of HFP and PVDF, for example, 2% by mass or more and 30% by mass or less of HFP and VDF. It only has to be united. If the 1st thin film 6B consists of this copolymer, the softness
  • the second thin film 6C preferably contains 0 mass% or more and 20 mass% or less of HFP and PVDF, for example, a copolymer of HFP and VDF of 20 mass% or less (excluding 0 mass%). It may consist of PVDF or PVDF. If the 2nd thin film 6C consists of this copolymer, the softness
  • the second thin film 6C will be further described. Since the second thin film 6C has less HFP than the first thin film 6B, the second thin film 6C has more adhesive material than the first thin film 6B. Therefore, since the second thin film 6C has better adhesiveness than the first thin film 6B, the first thin film 6B can be bonded to the surface of the negative electrode 5 via the second thin film 6C. As described above, the second thin film 6C has a function of adhering the first thin film 6B to the negative electrode 5 in addition to the function of making it difficult to diffuse foreign metal ions as compared with the first thin film 6B.
  • the separator 6 includes the first thin film 6B and the second thin film 6C. Accordingly, the foreign metal ions are diffused into the first thin film 6B or the second thin film 6C, so that the foreign metal ions can be prevented from reaching the surface of the negative electrode 5. Even if the metal foreign matter ions reach the surface of the negative electrode 5, the metal foreign matter is deposited in a direction substantially parallel to the surface of the negative electrode 5. Therefore, it is possible to prevent the metal foreign matter from being concentrated and deposited on one place of the negative electrode 5, thereby preventing the occurrence of an internal short circuit due to the contamination of the metal foreign matter, and thus the non-aqueous electrolyte 2 having excellent safety. Next battery can be provided.
  • the main layer 6A, the first thin film 6B, and the second thin film 6C are arranged in this order from the positive electrode 4 toward the negative electrode 5. Therefore, the foreign metal ions that have passed through the film having the highest ion permeability (main layer 6A) can be diffused into the film having the medium ion permeability (first thin film 6B). In addition, foreign metal ions that have passed through a film having a moderate ion permeability (first thin film 6B) can be diffused into the film having the lowest ion permeability (second thin film 6C). Therefore, foreign metal ions can be efficiently diffused into the first thin film 6B or the second thin film 6C.
  • the first thin film 6B is bonded to the surface of the negative electrode 5 via the second thin film 6C, and is integral with the main layer 6A. Therefore, the effect that the ion transmittance decreases stepwise from the positive electrode 4 toward the negative electrode 5 can be sufficiently exhibited. Further, it is possible to prevent a decrease in manufacturing yield of the electrode group 8.
  • each of the first thin film 6B and the second thin film 6C is deformed following the expansion or contraction of the negative electrode active material. Therefore, it can prevent that performance and safety fall during charge / discharge, and can prevent the fall of cycling characteristics.
  • the total thickness of the first thin film 6B and the second thin film 6C is much smaller than the thickness of the main layer 6A. Therefore, in this embodiment, since lithium ion diffusion is ensured, battery performance can be ensured.
  • Non-aqueous electrolyte secondary batteries generally have a problem that the capacity at the first discharge is lower (the irreversible capacity is large) than the capacity at the first charge. This is because an irreversible reaction such as film formation occurs in the carbon material, which is the negative electrode active material, or a metal or a compound containing a metal during the initial charge.
  • a technique of adding lithium to the negative electrode before forming the electrode group has been proposed (for example, Japanese Patent Application Laid-Open No. 2005-085633).
  • the separator 6 in this embodiment when the separator 6 in this embodiment is used, the metal foreign matter in the positive electrode 4 is dissolved in the nonaqueous electrolyte and then diffuses into the first thin film 6B or the second thin film 6C. Can be prevented from being deposited on the surface of the negative electrode 5. Therefore, in this embodiment, even when the dissolution of the metallic foreign matter starts immediately after the nonaqueous electrolyte is injected into the battery case, it is possible to prevent the occurrence of an internal short circuit due to the contamination of the metallic foreign matter.
  • the nonaqueous electrolyte secondary battery only needs to satisfy x / y> 1.05.
  • x is the total number of moles of lithium contained in the positive electrode and the negative electrode
  • y is the first metal in the positive electrode active material (for example, when the positive electrode active material is LiCoO 2 , the first metal is Co.
  • X and y can be obtained, for example, by ICP (inductively coupled plasma) analysis.
  • the molar ratio of lithium to the first metal is usually 1: 1 to 1.02. Therefore, if x / y> 1.05 is satisfied, lithium is added to the negative electrode before the electrode group is formed.
  • lithium may be deposited on the surface of the negative electrode active material layer 5B, or lithium may be part of the negative electrode current collector 5A or the negative electrode active material layer 5B. (For example, a lithium film is adhered to the surface of the negative electrode active material layer 5B, or the lithium film is welded to a portion of the negative electrode current collector where the negative electrode active material layer is not formed).
  • the arrangement of the main layer 6A, the first thin film 6B, and the second thin film 6C in the separator 6 is not limited to the arrangement shown in FIG. 3, and may be the arrangement shown below.
  • the first thin film 6B is provided on the surface of the positive electrode 4
  • the second thin film 6C is provided on the surface of the negative electrode 5
  • the main layer 6A is formed with the first thin film 6B. It is sandwiched between the second thin film 6C.
  • the ion permeability cannot be reduced step by step from the positive electrode 4 toward the negative electrode 5. Therefore, there may be a case where the metal foreign matter ions cannot be efficiently diffused into the first thin film 6B or the second thin film 6C.
  • the first thin film 6B and the second thin film 6C are arranged opposite to each other in the arrangement shown in FIG. 3, and in the third arrangement, the first thin film 6B and the first thin film 6B are arranged in the first arrangement.
  • the second thin film 6C is disposed opposite to each other.
  • the first thin film 6B is provided directly on the surface of the negative electrode 5 without passing through the second thin film 6C. Therefore, the adhesive strength between the first thin film 6B and the negative electrode 5 may not be ensured.
  • the main layer 6A is provided on the surface of the negative electrode 5
  • the first thin film 6B is provided on the surface of the positive electrode 4
  • the second thin film 6C is connected to the main layer 6A and the first layer. Between the two thin films 6B.
  • the first thin film 6B and the second thin film 6C are arranged opposite to each other in the fourth arrangement.
  • the main layer 6A is provided on the surface of the negative electrode 5 instead of the first thin film 6B and the second thin film 6C. For this reason, metal foreign matter ions may be deposited on the surface of the negative electrode 5, and the metal foreign matter deposited on the surface of the negative electrode 5 may reach the positive electrode 4 as shown in FIG.
  • the arrangement shown in FIG. 3 is preferable to the first to fifth arrangements.
  • the first to fifth arrangements it is possible to prevent the occurrence of an internal short circuit due to the mixing of metal foreign matter, compared to the case where the separator does not have the first thin film and the second thin film. Therefore, the effects in the present embodiment can be obtained to some extent even in the first to fifth arrangements.
  • the separator 6 preferably has a first thin film 6B and a second thin film 6C. If the separator does not have the second thin film 6C, the metal foreign matter ions may reach the surface of the negative electrode 5, and therefore it may not be possible to prevent the occurrence of an internal short circuit due to the contamination of the metal foreign matter. Moreover, since it is difficult to adhere the first thin film 6B to the negative electrode 5 or the like, the production yield of the electrode group 8 may be reduced, and the first thin film 6B is caused by expansion and contraction of the negative electrode active material. It may peel from the negative electrode 5 or the like. Further, if the separator 6 does not have the first thin film 6B, the metal foreign matter ions may not be sufficiently diffused. For this reason, the metal foreign matter is deposited intensively at one place and short-circuited. It may cause a malfunction that leads to
  • the separator 6 may have three or more thin films. In this case, it is preferable that the three or more thin films are arranged so that the ion transmittance decreases from the positive electrode 4 toward the negative electrode 5 for the reason described above. However, if the number of thin films increases too much, the occupancy rate of the thin films in the separator 6 increases, causing a decrease in the function of the separator 6. Further, if the number of thin films is increased without changing the total thickness of the thin films, the thickness of each thin film becomes very thin, so that it is difficult to form each thin film. What is necessary is just to determine the number of thin films in consideration of these. If the number of thin films is increased without changing the total thickness of the thin films, the boundary between the thin films may not be confirmed.
  • the film thickness of the first thin film 6B may be substantially the same as the film thickness of the second thin film 6C (for example, the film thickness of the first thin film 6B). May be 40% or more and 60% or less of the total thickness of the first thin film 6B and the second thin film 6C), or may be much thinner than the thickness of the second thin film 6C. It may be much thicker than the film thickness of the second thin film 6C. In any case, the effect of the present embodiment can be obtained. However, if the film thickness of the first thin film 6B is substantially the same as the film thickness of the second thin film 6C, both the effect produced by the first thin film 6B and the effect produced by the second thin film 6C can be obtained in a balanced manner. be able to. Therefore, the film thickness of the first thin film 6B is preferably substantially the same as the film thickness of the second thin film 6C.
  • the electrode group 8 may be formed by laminating the positive electrode 4 and the negative electrode 5 with the separator 6 interposed therebetween.
  • the nonaqueous electrolyte secondary battery may include a positive electrode current collector plate instead of the positive electrode lead 4L, and may include a negative electrode current collector plate instead of the negative electrode lead 5L. If current collection is performed using the current collector plate, the resistance during current collection can be reduced as compared with the case where current collection is performed using leads, so that the output of the nonaqueous electrolyte secondary battery can be increased.
  • the nonaqueous electrolyte secondary battery may include a laminate film instead of the battery case 1. If the electrode group 8 is wrapped with a laminate film, the amount of metal foreign matter derived from the metal case can be reduced as compared with the case where the electrode group 8 is accommodated in the battery case 1 made of metal. This can contribute to the effect of preventing the occurrence of an internal short circuit due to the mixing of foreign matter.
  • the positive electrode current collector 4A may be made of aluminum or a conductive material mainly composed of aluminum.
  • the positive electrode current collector 4A may be a long conductive substrate or a long foil, and may have a plurality of holes.
  • the thickness of the positive electrode current collector 4A is preferably 1 ⁇ m or more and 500 ⁇ m or less, and more preferably 10 ⁇ m or more and 20 ⁇ m or less. Thereby, the positive electrode 4 can be reduced in weight while maintaining the strength of the positive electrode 4.
  • the positive electrode active material is a composite oxide containing lithium, a first metal, and oxygen.
  • M is at least one of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B.
  • Me is at least one selected from Fe, Mn, Co and Ni.
  • z is greater than 0 and less than or equal to 1.
  • the composite oxide includes a phosphate compound.
  • the positive electrode active material may be one in which a part of the elements of the composite oxide is replaced with another element.
  • the positive electrode active material may be a metal oxide, lithium oxide, or a composite oxide surface-treated with a conductive agent, and the surface treatment is, for example, a hydrophobic treatment.
  • the average particle diameter of the positive electrode active material is preferably 5 ⁇ m or more and 20 ⁇ m or less.
  • the average particle diameter of the positive electrode active material is less than 5 ⁇ m, the surface area of the active material particles becomes extremely large, and therefore the amount of the binder necessary for fixing the active material in the electrode plate increases. For this reason, the amount of the positive electrode active material per electrode plate is reduced, which may cause a decrease in capacity.
  • the average particle diameter of the positive electrode active material exceeds 20 ⁇ m, streaks may occur on the surface of the slurry layer when the positive electrode mixture slurry is applied to the positive electrode current collector 4A. Therefore, the average particle size of the positive electrode active material is preferably 5 ⁇ m or more and 20 ⁇ m or less.
  • binder examples include PVDF, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polyacrylic acid methyl ester, polyacrylic acid ethyl ester, and polyacrylic acid.
  • Hexyl ester polymethacrylic acid, polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polymethacrylic acid hexyl ester, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene butadiene rubber or carboxymethylcellulose Etc.
  • the binder may be tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid and hexadiene. It is a copolymer or a mixture comprising two or more selected materials.
  • PVDF and its derivatives are chemically stable in the non-aqueous electrolyte secondary battery, and can sufficiently bind the positive electrode current collector 4A and the positive electrode active material or conductive agent, Furthermore, the positive electrode active material and the conductive agent can be sufficiently bound. Therefore, when PVDF or a derivative thereof is used as the binder, a nonaqueous electrolyte secondary battery excellent in cycle characteristics and discharge performance can be provided. In addition, since PVDF and its derivatives are inexpensive, the production cost of the nonaqueous electrolyte secondary battery can be suppressed by using PVDF or its derivatives as the binder. From the above, it is preferable to use PVDF or a derivative thereof as a binder. When PVDF is used as the binder, a positive electrode mixture slurry may be prepared using a solution in which PVDF is dissolved in N-methylpyrrolidone, and powdered PVDF is dissolved in the positive electrode mixture slurry. May be.
  • the conductive agent may be, for example, graphite such as natural graphite or artificial graphite, carbon black such as acetylene black (AB) or ketjen black, carbon fiber or metal Conductive fibers such as fibers may be used, carbon fluoride may be used, metal powders such as aluminum may be used, and conductive whiskers such as zinc oxide or potassium titanate may be used. It may be a conductive metal oxide such as titanium oxide or an organic conductive material such as a phenylene derivative.
  • a positive electrode mixture slurry is prepared by mixing a positive electrode active material, a binder, and a conductive agent with liquid components. At this time, the positive electrode mixture slurry only needs to contain a binder of 3.0 vol% or more and 6.0 vol% or less with respect to the positive electrode active material.
  • the obtained positive electrode mixture slurry is applied on both surfaces of the positive electrode current collector 4A and dried, and the obtained positive electrode plate is rolled. Thereby, a positive electrode having a predetermined thickness is produced.
  • the negative electrode current collector 5A is preferably made of stainless steel, nickel, copper, or the like.
  • the negative electrode current collector 5A may be a long conductive substrate or a long foil, and may have a plurality of holes.
  • the thickness of the negative electrode current collector 5A is preferably 1 ⁇ m or more and 500 ⁇ m or less, and more preferably 10 ⁇ m or more and 20 ⁇ m or less. Thereby, the negative electrode 5 can be reduced in weight while maintaining the strength of the negative electrode 5.
  • Examples of the negative electrode active material include carbon materials, metals, metal fibers, oxides, nitrides, silicon compounds, tin compounds, and various alloy materials.
  • the carbon material is, for example, various natural graphites, cokes, graphitized carbon, carbon fibers, spherical carbon, various artificial graphites, or amorphous carbon.
  • the silicon compound may be SiO x (where 0.05 ⁇ x ⁇ 1.95), and a part of Si may be B, Mg, Ni, Ti, Mo, Co, Ca, Cr, Cu, Fe, It may be a silicon alloy substituted with at least one element selected from the group consisting of Mn, Nb, Ta, V, W, Zn, C, N and Sn, or may be a silicon solid solution. .
  • the tin compound may be, for example, Ni 2 Sn 4 , Mg 2 Sn, SnO x (where 0 ⁇ x ⁇ 2), SnO 2 or SnSiO 3 .
  • the negative electrode active material two of the above listed materials may be used alone, or two or more of them may be used in combination.
  • a method for producing such a negative electrode 5 will be described.
  • a carbon material is used as the negative electrode active material
  • a negative electrode active material (carbon material) and a binder are mixed with a liquid component to prepare a negative electrode mixture slurry.
  • the obtained negative electrode mixture slurry is applied on both surfaces of the negative electrode current collector 5A and dried, and the obtained negative electrode plate is rolled. Thereby, the negative electrode 5 having a predetermined thickness is produced.
  • the negative electrode active material may be vapor-deposited on both surfaces of the negative electrode current collector 5A.
  • the negative electrode 5 may be preliminarily provided with lithium to compensate for the irreversible capacity.
  • the configuration of the separator 6 is as shown in the first embodiment.
  • the main layer 6A may have the following configuration.
  • the main layer 6A may be one (insulating porous particles) in which insulating particles (for example, metal oxide or metal sulfide) are bound to each other, or a microporous thin film, a woven fabric or a nonwoven fabric made of polyolefin. You may have both with a porous insulating film.
  • the insulating particles preferably have excellent insulating properties and are resistant to deformation even at high temperatures, and the porous insulating film is made of an insulating fine powder made of an oxide such as aluminum oxide, magnesium oxide or titanium oxide. It is preferable that it is applied on top.
  • the main layer 6A has a shutdown function, so that the temperature increase of the nonaqueous electrolyte secondary battery can be suppressed.
  • a porous insulating film is used as the main layer 6A, the shrinkage of the main layer 6A can be prevented even when the temperature of the nonaqueous electrolyte secondary battery becomes very high (eg, 200 ° C. or higher). The occurrence of a short circuit can be prevented. What is necessary is just to select the structure of 6 A of main body layers according to the use etc. of a nonaqueous electrolyte secondary battery.
  • the main layer 6A may be a single layer film made of one kind of material or a composite film made of two or more kinds of materials, It may be a multilayer film in which two or more layers made of different materials are laminated.
  • the main layer 6A preferably has a porosity of 30% to 70%, and more preferably has a porosity of 35% to 60%.
  • the porosity is the ratio of the volume of the holes to the total volume of the main layer 6A.
  • the non-aqueous electrolyte may be a liquid non-aqueous electrolyte, a gel-like non-aqueous electrolyte, or a solid non-aqueous electrolyte.
  • an electrolyte for example, a lithium salt
  • the non-aqueous electrolyte is held by the polymer material.
  • the polymer material include PVDF, polyacrylonitrile, polyethylene oxide, polyvinyl chloride, polyacrylate, and polyvinylidene fluoride hexafluoropropylene.
  • the solid nonaqueous electrolyte includes a polymer solid electrolyte.
  • non-aqueous solvent a known non-aqueous solvent can be used, and for example, a cyclic carbonate ester, a chain carbonate ester or a cyclic carboxylic acid ester can be used.
  • the cyclic carbonate is, for example, propylene carbonate (PC) or ethylene carbonate (EC).
  • the chain carbonate is, for example, diethyl carbonate (DEC), ethyl methyl carbonate (EMC) or dimethyl carbonate (DMC).
  • the cyclic carboxylic acid ester is, for example, ⁇ -butyrolactone (GBL; gamma-butyrolactone) or ⁇ -valerolactone (GVL).
  • GBL ⁇ -butyrolactone
  • VTL ⁇ -valerolactone
  • the non-aqueous solvent one of the non-aqueous solvents listed above may be used alone, or two or more thereof may be used in combination.
  • Examples of the electrolyte include LiClO 4 , LiBF 4 , LiPF 6 , LiAlCl 4 , LiSbF 6 , LiSCN, LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiB 10 Cl 10 , lower aliphatic lithium carboxylate, LiCl, LiBr , LiI, chloroborane lithium, borates, or imide salts.
  • borates include bis (1,2-benzenediolate (2-)-O, O ′) lithium borate, bis (2,3-naphthalenedioleate (2-)-O, O ′) boron.
  • Lithium acid bis (2,2′-biphenyldiolate (2-)-O, O ′) lithium borate, or bis (5-fluoro-2-olate-1-benzenesulfonic acid-O, O ′) boron Lithium acid.
  • the imide salts include lithium bistrifluoromethanesulfonate imide ((CF 3 SO 2 ) 2 NLi), lithium trifluoromethanesulfonate nonafluorobutanesulfonate (LiN (CF 3 SO 2 ) (C 4 F 9 ). SO 2)), or a bispentafluoroethanesulfonyl imide lithium ((C 2 F 5 SO 2 ) 2 NLi).
  • the electrolyte one of the electrolytes listed above may be used alone, or two or more may be used in combination.
  • the concentration of the electrolyte is preferably 0.5 mol / m 3 or more and 2 mol / m 3 or less.
  • the nonaqueous electrolytic solution may contain the following additives in addition to the nonaqueous solvent and the electrolyte.
  • This additive is decomposed on the surface of the negative electrode active material layer, whereby a film having high lithium ion conductivity is formed on the surface of the negative electrode active material layer. Therefore, the charge / discharge efficiency of the nonaqueous electrolyte secondary battery can be increased.
  • Examples of the additive having such a function include vinylene carbonate (VC), 4-methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, 4-ethyl vinylene carbonate, 4,5-diethyl vinylene carbonate, 4 -Propyl vinylene carbonate, 4,5-dipropyl vinylene carbonate, 4-phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl ethylene carbonate (VEC) or divinyl ethylene carbonate.
  • VEC vinyl ethylene carbonate
  • one of the materials listed above may be used alone, or two or more of the materials listed above may be used in combination.
  • the additive it is preferable to use at least one selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, and divinyl ethylene carbonate.
  • the additive may be one in which some of the hydrogen atoms in the materials listed above are substituted with fluorine atoms.
  • the non-aqueous electrolyte may contain a benzene derivative in addition to the non-aqueous solvent and the electrolyte.
  • the benzene derivative preferably has a phenyl group, and preferably has a phenyl group and a cyclic compound group bonded to positions adjacent to each other.
  • the benzene derivative is, for example, cyclohexylbenzene, biphenyl, or diphenyl ether.
  • the cyclic compound group is, for example, a phenyl group, a cyclic ether group, a cyclic ester group, a cycloalkyl group, or a phenoxy group.
  • the nonaqueous solvent should just contain 10 vol% or less of benzene derivatives. If the non-aqueous electrolyte contains such a benzene derivative, during overcharge, the benzene derivative is decomposed and a film is formed on the surface of the electrode, thereby inactivating the non-aqueous electrolyte secondary battery. Can do.
  • the positive electrode lead 4L is connected to a portion of the positive electrode current collector 4A where the positive electrode mixture layer 4B is not provided, and the negative electrode lead 5L is connected to a portion of the negative electrode current collector 5A where the negative electrode active material layer 5B is not provided. Connect.
  • the positive electrode 4 and the negative electrode 5 are wound through the separator 6 to produce the electrode group 8. At this time, it is confirmed that the positive electrode lead 4L and the negative electrode lead 5L extend in opposite directions.
  • the upper insulating plate 7 a is disposed at the upper end of the electrode group 8
  • the lower insulating plate 7 b is disposed at the lower end of the electrode group 8.
  • the negative electrode lead 5 ⁇ / b> L is connected to the battery case 1
  • the positive electrode lead 4 ⁇ / b> L is connected to the sealing plate 2
  • the electrode group 8 is accommodated in the battery case 1.
  • a non-aqueous electrolyte is injected into the battery case 1 by a decompression method.
  • the opening 1 a of the battery case 1 is sealed with the sealing plate 2 via the gasket 3.
  • Example 1 Manufacturing method of non-aqueous electrolyte secondary battery (Battery 1) -Fabrication of positive electrode- First, LiNi 0.82 Co 0.15 Al 0.03 O 2 (positive electrode active material) having an average particle diameter of 10 ⁇ m was prepared.
  • NMP N-methylpyrrolidone
  • the positive electrode mixture slurry was applied on both sides of an aluminum foil (positive electrode current collector) having a thickness of 15 ⁇ m and dried, and the obtained electrode plate was rolled. As a result, a positive electrode plate having a thickness of 0.157 mm was obtained. This positive electrode plate was cut into a width of 57 mm and a length of 564 mm to obtain a positive electrode.
  • lithium was deposited on each surface of the silicon-containing film by vacuum deposition. Thereby, a lithium film having a density of 3.2 g / m 2 is formed on each surface of the silicon-containing film (a lithium film having a film thickness of 6 ⁇ m when the density of lithium is converted into a film thickness of the lithium film). It was done. Thereafter, the negative electrode plate was handled in a dry air environment having a dew point of ⁇ 30 ° C. or lower.
  • a polymer layer (second thin film, hereinafter referred to as “negative electrode polymer layer”) having a thickness of 1 ⁇ m was formed.
  • a polymer layer (first thin film, hereinafter referred to as “main layer side polymer layer”) having a thickness of 1 ⁇ m was formed. Thereafter, the negative electrode plate on which the two polymer layers were formed was cut into a width of 58.5 mm and a length of 750 mm to obtain a negative electrode.
  • a positive electrode lead made of aluminum was connected to the positive electrode current collector, and a negative electrode lead made of nickel was connected to the negative electrode current collector. Thereafter, the positive electrode and the negative electrode are arranged so that the positive electrode lead and the negative electrode lead extend in opposite directions, and a polyethylene film (main layer, thickness 20 ⁇ m) is sandwiched between the positive electrode and the main layer side polymer layer, The positive electrode, the negative electrode, and the polyethylene film were wound. Thereby, the electrode group was produced.
  • the total number of moles of lithium contained in the positive electrode and the negative electrode of this electrode group was determined by ICP analysis, when the total number of moles of Ni, Co and Al contained in the positive electrode was 1, the total number of moles of lithium was 1. 13.
  • an upper insulating film was disposed at the upper end of the electrode group, and a lower insulating plate was disposed at the lower end thereof.
  • the negative electrode lead was welded to the battery case and the positive electrode lead was welded to the sealing plate, and the electrode group was housed in the battery case.
  • a non-aqueous electrolyte was injected into the battery case by a decompression method.
  • the sealing plate was caulked to the open end of the battery case via a gasket. In this way, the battery 1 was produced.
  • a battery 3 was produced in the same manner as the battery 1 except that the thickness of the negative electrode side polymer layer was 3 ⁇ m and the thickness of the main layer side polymer layer was 5 ⁇ m.
  • a battery 4 was produced in the same manner as the battery 1 except that the negative electrode polymer layer was a PVDF film. Specifically, an N-methyl-2-pyrrolidone solution containing only PVDF (concentration: 12% by mass) was applied on one side of the negative electrode plate and dried.
  • Battery 5 A battery 5 was produced in the same manner as the battery 1 except that the polymer layer was not formed on the surface of the negative electrode plate.
  • a battery 6 was produced in the same manner as the battery 1 except that only one polymer layer was formed on one side of the negative electrode plate. Specifically, an N-methyl-2-pyrrolidone solution containing only PVDF (concentration: 12% by mass) was applied on one side of the negative electrode plate and dried. Thereafter, this negative electrode plate was cut to obtain a negative electrode.
  • the battery voltage of a battery in which an internal short circuit has occurred is lower than the battery voltage of a battery in which no internal short circuit has occurred.
  • the voltage of the battery of Example 1 is about 2.8V. Therefore, in Example 1, the case where the measured battery voltage was lower than 2.6 V was judged as defective, and the number of defective batteries (the number of parameters was 50) was counted.
  • the battery voltage was measured 48 hours after each of the batteries 1 to 7 was fabricated, and the number of batteries in which an internal short circuit occurred was counted. The result is shown in the defect rate 48 hours after assembly in FIG.
  • Example 2 In Example 2, the negative electrode side polymer layer and the main layer side polymer layer were fixed on one side of a polyethylene film to produce a separator.
  • a battery 8 was prepared according to the same method as the battery 1 except for the configuration of the negative electrode side polymer layer and the main layer side polymer layer, the negative electrode preparation method, and the negative electrode side polymer layer and main layer side polymer layer preparation method. .
  • N-methyl-2-pyrrolidone solution containing only PVDF (concentration: 12% by mass) was applied onto the main polymer layer and then dried.
  • the thickness after drying was 22 ⁇ m.
  • Battery 9 A battery 9 was produced according to the same method as the battery 8 except for the respective configurations of the negative electrode side polymer layer and the main layer side polymer layer.
  • the thickness after drying was 20 ⁇ m.
  • the cross section of the polyethylene film was observed after drying, it was found that the polymer soaked into one side of the polyethylene film.
  • a battery 10 was produced according to the same method as the battery 8 except that only the main layer side polymer layer was formed on one side of the polyethylene film.
  • Example 3 graphite was used as the negative electrode active material.
  • a battery 11 was produced in the same manner as the battery 2 except that graphite was used as the negative electrode active material.
  • this negative electrode mixture slurry was applied on both sides of a copper foil (negative electrode current collector) having a thickness of 8 ⁇ m and dried, and the obtained electrode plate was rolled. As a result, a negative electrode plate having a thickness of 0.156 mm was obtained.
  • This negative electrode plate was heat-treated with hot air at 190 ° C. for 8 hours in a nitrogen atmosphere. The negative electrode plate after the heat treatment was cut to obtain a negative electrode having a thickness of 0.156 mm, a width of 58.5 mm, and a length of 750 mm.
  • the negative electrode active material which exists in the part (edge part in the longitudinal direction of a negative electrode) which does not oppose a positive electrode active material when forming an electrode group was removed.
  • a lithium film having a thickness of 100 ⁇ m, a width of 50 mm, and a length of 50 mm was pasted on the end in the longitudinal direction of the negative electrode (the portion where the copper foil was exposed).
  • Battery 12 A battery 12 was produced according to the same method as the battery 11 except that the negative electrode was produced without attaching the lithium film to the copper foil.
  • Battery 13 A battery 13 was produced in the same manner as the battery 11 except that the polymer layer was not formed on the surface of the negative electrode plate.
  • the capacity of the battery was measured.
  • the battery has a capacity of 25 ° C. with a constant current of 1.4 A until the voltage reaches 4.2 V, and after charging with a constant voltage of 4.2 V until the current reaches 50 mA, the battery capacity is 0
  • the battery in which an internal short circuit occurred was analyzed in the same manner.
  • a metal element such as Fe or Ni was deposited in a needle shape, and the deposit penetrated the separator and reached the positive electrode. .
  • the total number of moles of the metal present in the polyethylene film, the negative electrode side polymer layer, the main layer side polymer layer, and the electrolyte solution was quantified by ICP analysis.
  • the number of moles was almost the same in batteries 1 to 7. That is, the amount of the dissolved metal foreign matter was the same in the batteries 1 to 4 and the batteries 5 to 7.
  • the deposit shape of the metal foreign matter was different between the batteries 1 to 4 and the batteries 5 to 7, no short circuit occurred in the batteries 1 to 4, whereas an internal short circuit occurred in the batteries 5 to 7.
  • Example 2- The same result as in Example 1 was obtained.
  • the present invention is useful, for example, as a power source for consumer equipment, a power source mounted in an automobile, or a power source for large tools.

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  • Chemical Kinetics & Catalysis (AREA)
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Abstract

L'invention concerne un séparateur (6) disposé entre une électrode positive (4) et une électrode négative (5) et comportant la couche principale (6A) et de multiples films minces (6B, 6C). Chacun des multiples films minces (6B, 6C) a une épaisseur inférieure à celle de la couche principale (6A) et une valeur de la perméabilité ionique inférieure à celle de la couche principale (6A). Les multiples films minces (6B, 6C) ont des valeurs de perméabilité ionique différentes les unes des autres.
PCT/JP2010/006405 2009-12-11 2010-10-29 Batterie secondaire à électrolyte non aqueux WO2011070710A1 (fr)

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WO2014156891A1 (fr) * 2013-03-29 2014-10-02 新神戸電機株式会社 Batterie secondaire au lithium-ion

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