WO2022085371A1 - Electrolytic copper foil, negative electrode for lithium ion secondary cell, and lithium ion secondary cell - Google Patents

Electrolytic copper foil, negative electrode for lithium ion secondary cell, and lithium ion secondary cell Download PDF

Info

Publication number
WO2022085371A1
WO2022085371A1 PCT/JP2021/035367 JP2021035367W WO2022085371A1 WO 2022085371 A1 WO2022085371 A1 WO 2022085371A1 JP 2021035367 W JP2021035367 W JP 2021035367W WO 2022085371 A1 WO2022085371 A1 WO 2022085371A1
Authority
WO
WIPO (PCT)
Prior art keywords
copper foil
electrolytic copper
electrolytic
lithium ion
ion secondary
Prior art date
Application number
PCT/JP2021/035367
Other languages
French (fr)
Japanese (ja)
Inventor
伸 菊池
亮二 高澤
正靖 笠原
竜介 中崎
Original Assignee
古河電気工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 古河電気工業株式会社 filed Critical 古河電気工業株式会社
Priority to JP2022515789A priority Critical patent/JPWO2022085371A1/ja
Publication of WO2022085371A1 publication Critical patent/WO2022085371A1/en

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D1/00—Electroforming
    • C25D1/04—Wires; Strips; Foils
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • 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

Definitions

  • the present invention relates to an electrolytic copper foil, a negative electrode for a lithium ion secondary battery using the electrolytic copper foil, and a lithium ion secondary battery including the negative electrode for the lithium ion secondary battery.
  • a copper foil may be used as a negative electrode current collector of a lithium ion secondary battery, but the copper foil may break due to expansion and contraction of the negative electrode material during charging and discharging of the lithium ion secondary battery.
  • the copper foil and the negative electrode material that are in close contact with each other are locally peeled off during charging and discharging, and stress during expansion and contraction is concentrated on the peeled portion, so that the copper foil may break.
  • Patent Documents 1 and 2 disclose electrolytic copper foils that can be used as a negative electrode current collector for a lithium ion secondary battery and have improved adhesion to a negative electrode material by controlling surface roughness.
  • Patent Document 3 discloses an electrolytic copper foil for a secondary battery, which can withstand expansion and contraction of a negative electrode material during charging and discharging and has excellent bending resistance.
  • Patent Document 4 discloses a technique for manufacturing a secondary battery having excellent performance by using a copper foil in which sagging, wrinkling, and tearing are suppressed by controlling surface roughness and the like. In recent years, research on lithium-ion secondary batteries has progressed, and further improvement in performance is required. Therefore, copper foils that are less likely to break during charging and discharging are required. Since the electrolytic copper foils disclosed in Patent Documents 1 to 4 may have insufficient mechanical properties and adhesion to the negative electrode material, they may be broken during charging / discharging of the lithium ion secondary battery.
  • An object of the present invention is to provide an electrolytic copper foil that is less likely to break. Another object of the present invention is to provide a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery in which the negative electrode current collector is less likely to break during charging and discharging.
  • the foil thickness is t (unit: ⁇ m), and the concave average volume, which is the average value of the volumes of the concave portions formed on the electrolytic precipitation end surface, is VAV (unit: ⁇ m 3 ). ), The elongation rate measured by pulling along the length direction is E (unit is%), and when the concave average volume VAV is measured using a white interference microscope, the foil thickness t is 10 or more and 20 or less.
  • VAV ⁇ t which is the product of the concave average volume VAV and the foil thickness t, is more than 0 and 1000 or less, and E / t obtained by dividing the elongation rate E by the foil thickness t is 0.9 or more and 1.8 or less. Is the gist.
  • the negative electrode for a lithium ion secondary battery according to another aspect of the present invention includes the electrolytic copper foil according to the above aspect. Further, it is a gist that the lithium ion secondary battery according to another aspect of the present invention includes a negative electrode for a lithium ion secondary battery according to the other aspect.
  • the electrolytic copper foil of the present invention is less likely to break. Further, the negative electrode for a lithium ion secondary battery and the lithium ion secondary battery of the present invention are less likely to break in the negative electrode current collector during charging and discharging.
  • the electrolytic copper foil according to the embodiment of the present invention has a foil thickness of t (unit: ⁇ m) and a concave average volume (Valleys Average Volume) which is an average value of the volumes of the concave portions formed on the electrolytic precipitation end surface.
  • VAV unit: ⁇ m 3
  • E unit:%
  • the foil thickness is t.
  • VAV ⁇ t which is the product of the average volume VAV of the recess and the foil thickness t, is more than 0 and 1000 or less
  • E / t obtained by dividing the elongation rate E by the foil thickness t is 0.9 or more and 1 It is 0.8 or less. Due to such a configuration, the electrolytic copper foil of the present embodiment is unlikely to break.
  • the electrolytic copper foil of the present embodiment can be used as a negative electrode current collector of a lithium ion secondary battery (mainly a cylindrical lithium ion secondary battery). That is, the negative electrode for the lithium ion secondary battery of the present embodiment includes the electrolytic copper foil of the present embodiment. Further, the lithium ion secondary battery of the present embodiment includes the negative electrode for the lithium ion secondary battery of the present embodiment. Since the electrolytic copper foil of the present embodiment is hard to break, the negative electrode for the lithium ion secondary battery and the lithium ion secondary battery of the present embodiment are hard to break in the negative electrode current collector during charging and discharging.
  • the electrolytic copper foil of the present embodiment will be described in more detail.
  • the present inventor has found that the electrolytic copper foil having both high stretchability and smoothness (low profile) of the electrolytic precipitation end surface has a negative electrode material during charging and discharging of a lithium ion secondary battery. It was found that breakage is unlikely to occur even if it expands and contracts.
  • the electrolytic copper foil has high stretchability, the electrolytic copper foil can follow the expansion and contraction of the negative electrode material, so that breakage is unlikely to occur. Further, if the concave average volume VAV, which is the average value of the volumes of the fine recesses formed on the electrolytic precipitation end surface, is small and the electrolytic precipitation end surface is smooth, the electrolytic copper foil and the negative electrode material that are in close contact with each other are used. Since the adhesion force of the metal is uniform over the entire contact surface, it is possible to prevent local peeling between the electrolytic copper foil and the negative electrode material that are in close contact with each other during charging and discharging.
  • VAV concave average volume
  • VAV which is the average value of the volumes of the fine recesses formed on the electrolytic precipitation end surface
  • the relationship between the foil thickness of the electrolytic copper foil and the elongation rate due to tension is often unclear, and even with the electrolytic copper foil of the same foil thickness, the characteristics such as the elongation rate have varied.
  • the foil thickness is increased, the tensile breakage of the electrolytic copper foil is accelerated during charging and discharging of the lithium ion secondary battery due to the change in the copper precipitation mechanism during electrolytic plating (copper plating for producing electrolytic copper foil). There was also the problem of.
  • the present inventor has found that the value obtained by normalizing the elongation rate by the foil thickness (that is, the parameter E / t) falls within a certain region by controlling the electrolytic conditions of the electrolytic plating. Then, it was found that the lithium ion secondary battery manufactured by using the electrolytic copper foil thus obtained as the negative electrode current collector is less likely to break in the negative electrode current collector during charging and discharging.
  • a smooth electrolytic copper foil having a small surface roughness such as Ra and Rz is less likely to break.
  • the surface roughness of Ra, Rz, etc. is calculated from the profile in any one line on the surface of the electrolytic copper foil, and is the size of the fine recesses existing in the region having a certain area. Etc. are numerical values that are not sufficiently expressed.
  • the present inventor has found that, during electrolytic plating, copper crystal grows in the thickness direction of the electrolytic copper foil, so that a large number of cubic micrometer-scale fine recesses are formed on the surface of the electrolytic copper foil. I found. Then, it has been found that when the volume of the concave portion is large, when the negative electrode material expands and contracts during charging and discharging of the lithium ion secondary battery, the concave portion serves as a starting point and the electrolytic copper foil is likely to break. The recess formed by this copper crystal growth may become larger in proportion to the foil thickness.
  • the present inventor reduces the average recess volume VAV, which is the average value of the volumes of the recesses formed on the end surface of electrolytic precipitation, and reduces the average volume VAV of the recesses due to the foil thickness. It has been found that an electrolytic copper foil having a high elongation rate and less likely to break can be obtained by controlling the influence on the sheet.
  • FIG. 2 is a white interference contrast microscope image showing the unevenness formed on the electrolytic precipitation end surface of the electrolytic copper foil, and the height is represented by the shade of color.
  • FIG. 3 is a diagram showing a profile of the electrolytic precipitation end surface of the electrolytic copper foil, and is a profile in one line in the white interference contrast microscope image of FIG. The portion lower than the horizontal line having a height of 0 ⁇ m set in accordance with the ISO 25178 rule is the recess formed on the electrolytic precipitation end surface.
  • the recessed average volume VAV is affected by two factors: suppressing copper crystal growth in the thickness direction of the electrolytic copper foil and increasing the foil thickness. Therefore, when estimating the degree of suppression of crystal growth from the recessed average volume VAV for electrolytic copper foils having different foil thicknesses, it is necessary to compare VAV ⁇ t, which is the product of the recessed average volume VAV and the foil thickness t. be. From the above, it was found that by defining both the parameter VAV ⁇ t and the parameter E / t, the target electrolytic copper foil that is less likely to break can be obtained.
  • the foil thickness t needs to be 10 ⁇ m or more and 20 ⁇ m or less, but is preferably 12 ⁇ m or more and 20 ⁇ m or less.
  • the organic additive in the electrolytic solution functions in order to fill the large unevenness caused by the crystal growth in the thickness direction of the electrolytic copper foil, and the organic additive in the electrolytic solution functions in the thickness direction of the electrolytic copper foil. The effect of suppressing the crystal growth of copper can be obtained.
  • the concave average volume VAV tends to be large, and tensile fracture is accelerated.
  • the probability is high.
  • the electrolysis time required for foil production becomes long, so that it is easily affected by the decomposition and consumption of organic additives, and there are places where the average volume VAV of the recesses becomes extremely large. As a result, there is an increased probability that a local decrease in elongation will occur.
  • the parameter VAV ⁇ t needs to be 0 excess 1000 or less, but is preferably 0 excess 400 or less.
  • the surface of the electrolytic copper foil is smooth, so that the adhesion between the electrolytic copper foil and the negative electrode material tends to be uniform over the entire contact surface. Therefore, local peeling between the electrolytic copper foil and the negative electrode material, which are in close contact with each other, is suppressed during charging / discharging, so that breakage is less likely to occur during charging / discharging.
  • the parameter VAV ⁇ t is within the above range, the adhesive force between the electrolytic copper foil and the negative electrode material is sufficiently exhibited, so that breakage is unlikely to occur during charging and discharging.
  • the parameter E / t needs to be 0.9 or more and 1.8 or less, but is preferably 1.2 or more and 1.7 or less, and more preferably 1.3 or more and 1.6 or less.
  • the electrolytic copper foil has a high elongation rate, so that fracture is unlikely to occur during charging and discharging.
  • the root mean square height Sq of the electrolytic precipitation end surface of the electrolytic copper foil of the present embodiment measured using a white interference microscope is preferably 0.1 ⁇ m or more and 0.4 ⁇ m or less, preferably 0.1 ⁇ m or more and 0. It is more preferably .25 ⁇ m or less.
  • the adhesion between the electrolytic copper foil and the negative electrode material tends to be higher due to the anchor effect. Further, when the root mean square height Sq of the electrolytic precipitation end surface is within the above range, the electrolytic precipitation end surface is sufficiently smooth, so that the adhesion between the electrolytic copper foil and the negative electrode material that are in close contact with each other is strong. It becomes uniform over the entire contact surface. Therefore, local peeling between the electrolytic copper foil and the negative electrode material, which are in close contact with each other, is suppressed during charging / discharging, so that fracture is less likely to occur during charging / discharging.
  • the electrolytic copper foil of the present embodiment preferably has a tensile strength of 300 MPa or more and 380 MPa or less measured by pulling along the length direction. When the tensile strength is within the above range, the electrolytic copper foil is less likely to break, and the negative electrode material has more excellent followability to expansion and contraction.
  • the tensile strength of the electrolytic copper foil is measured by pulling it along the length direction, and the "length direction" of the electrolytic copper foil in the present invention means MD (Machine Direction), for example, electrolysis.
  • MD Machine Direction
  • the copper foil is formed by plating on the surface of the rotating electrode using the rotating electrode at the time of manufacturing the copper foil, it means the rotation direction of the rotating electrode.
  • the electrolytic copper foil of the present embodiment can be used not only for the negative electrode current collector of the lithium ion secondary battery but also for other purposes.
  • the electrolytic copper foil of the present embodiment can be suitably used as a copper foil for a printed wiring board. Since the electrolytic copper foil of the present embodiment has both high stretchability and smoothness of the electrolytic precipitation end surface, it is attached to the copper foil at the time of manufacturing a printed wiring board (for example, at the time of heat pressing). Even when the resin such as the epoxy resin to be combined expands and contracts, it follows the expansion and contraction, so that it is unlikely to break.
  • the electrolytic copper foil can be produced, for example, by using an electrolytic precipitation device as shown in FIG.
  • the electrolytic precipitation device of FIG. 1 includes an insoluble electrode 12 made of titanium coated with a platinum group element or an oxide thereof, and a titanium rotating electrode 11 provided facing the insoluble electrode 12. Copper plating is performed using the electrolytic precipitation device shown in FIG. 1, copper is deposited on the surface (columnar surface) of the columnar rotary electrode 11 to form a copper foil, and the copper foil is peeled off from the surface of the rotary electrode 11. Thereby, the electrolytic copper foil of the present embodiment can be manufactured.
  • electrolytic copper is controlled by controlling conditions such as current density, electrolytic solution temperature, and electrolytic solution composition (for example, concentration of copper ions, sulfuric acid, chlorine ions, and additives in the electrolytic solution). It is possible to suppress the growth of copper crystals in the thickness direction of the foil. As a result, the electrolytic copper foil having a small concave average volume VAV, a small change in the surface texture (for example, concave average volume VAV, root mean square height Sq) due to the foil thickness of the electrolytic copper foil, and having a high elongation rate can be obtained. Obtainable.
  • an example of a method of producing an electrolytic copper foil by performing copper plating will be described in more detail with reference to FIG.
  • a current is applied using the rotating electrode 11 as a cathode and the insoluble electrode 12 as an anode.
  • the insoluble electrode 12 for example, a DSE (Dimensionally Stable Electrode) electrode (registered trademark) can be used.
  • the electrolytic solution 13 for example, an aqueous solution containing sulfuric acid and copper sulfate can be used as the electrolytic solution 13, for example.
  • the copper concentration of the electrolytic solution 13 can be, for example, 50 to 150 g / L, and the sulfuric acid concentration can be, for example, 20 to 200 g / L.
  • Additives such as organic additives and inorganic additives may be added to the electrolytic solution 13 used for copper plating from the viewpoint of smoothing the electrolytic copper foil and controlling mechanical properties. By adding the additive, the strength, elongation, and surface roughness of the electrolytic copper foil under normal conditions can be improved, and the crystal growth of copper in copper plating can be suppressed.
  • One type of additive may be used alone, or two or more types may be used in combination.
  • organic additive examples include ethylenethiourea, polyethylene glycol, and Janus Green.
  • metal chloride such as sodium chloride (NaCl) or hydrogen chloride (HCl) can be used as a source of chloride ions.
  • chloride ion chloride ion
  • ethylenethiourea polyethylene glycol and Janus Green
  • copper crystals may grow in the thickness direction of the electrolytic copper foil, but at least one of ethylenethiourea, polyethylene glycol and yanus green is added to the electrolytic solution 13 at a concentration in the above range. Then, the effect of suppressing the crystal growth of copper in the thickness direction of the electrolytic copper foil becomes large.
  • the electrolytic conditions in copper plating can be, for example, as follows. That is, the liquid temperature of the electrolytic solution 13 is 45 to 65 ° C., and the current density is 25 to 50 A / dm 2 . At the time of copper plating, the temperature of the electrolytic solution 13 may rise due to the resistance heat generation of the anode and the cathode, and the organic additive may be decomposed. Therefore, it is preferable to suppress the current density to the above-mentioned low value.
  • the surface of the electrolytic copper foil produced as described above may be surface-treated.
  • the surface treatment will be described below.
  • the surface of the electrolytic copper foil may be subjected to a rust preventive treatment.
  • the rust preventive treatment include an inorganic rust preventive treatment and an organic rust preventive treatment.
  • the inorganic rust preventive treatment include chromate treatment and plating treatment, and chromate treatment may be applied to the plating layer by the plating treatment.
  • the plating treatment include nickel plating, nickel alloy plating, cobalt plating, cobalt alloy plating, zinc plating, zinc alloy plating, tin plating, and tin alloy plating.
  • the organic rust preventive treatment include surface treatment using benzotriazole.
  • the surface that has been subjected to the rust preventive treatment may be further subjected to surface treatment (silane treatment) using a silane coupling agent.
  • silane treatment silane treatment
  • a functional group having a strong affinity with an adhesive is imparted to the surface of the electrolytic copper foil (the surface on the bonding side with the negative electrode material or the resin), so that the electrolytic copper foil and the negative electrode material are provided. Adhesion with the resin and the resin is further improved, and the rust resistance and moisture absorption heat resistance of the electrolytic copper foil are further improved. Therefore, such an electrolytic copper foil is suitable as an electrolytic copper foil for a negative electrode current collector of a lithium ion secondary battery or a printed wiring board.
  • the rust preventive treatment and the silane coupling agent treatment increase the adhesion strength between the active material of the lithium ion secondary battery and the electrolytic copper foil, and play a role of preventing deterioration of the charge / discharge cycle characteristics of the lithium ion secondary battery.
  • the surface of the electrolytic copper foil may be roughened before the above-mentioned rust preventive treatment is applied.
  • a plating method, an etching method, or the like can be preferably adopted.
  • the plating method is a method of roughening the surface by forming a thin film layer having irregularities on the surface of the untreated electrolytic copper foil. Examples of the plating method include an electrolytic plating method and an electroless plating method.
  • the roughening treatment by the plating method for example, a method of forming a plating film containing copper as a main component such as copper or a copper alloy on the surface of an untreated electrolytic copper foil is preferable.
  • a method by physical etching or chemical etching is preferable. Examples of the physical etching include a method of etching by sandblasting and the like, and examples of the chemical etching include etching performed by using a treatment liquid containing an inorganic acid or an organic acid, an oxidizing agent and an additive.
  • Example ⁇ Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
  • the electrolytic copper foils of Examples 1 to 19 and Comparative Examples 1 and 2 are manufactured, negative electrode current collectors are manufactured using these electrolytic copper foils, and a lithium ion secondary battery is manufactured using these negative electrode current collectors.
  • a lithium ion secondary battery was manufactured using these negative electrode current collectors.
  • various characteristics of the electrolytic copper foil and the lithium ion secondary battery were evaluated.
  • a method for manufacturing an electrolytic copper foil and a lithium ion secondary battery and a method for evaluating various characteristics will be described.
  • An aqueous solution containing sulfuric acid, copper sulfate pentahydrate, and additives was used as the electrolytic solution.
  • additives ethylene thiourea, polyethylene glycol, and Janus Green were used.
  • Table 1 shows the concentrations of sulfuric acid, copper sulfate pentahydrate, and each additive.
  • the concentration of copper sulfate pentahydrate is the concentration as copper.
  • Table 1 shows the chlorine concentration in the electrolytic solution.
  • the positive electrode material paste was prepared by kneading. This positive electrode material paste was uniformly applied onto the aluminum foil with a thickness of 15 ⁇ m.
  • the aluminum foil coated with the positive electrode material paste was dried in a nitrogen atmosphere to volatilize the solvent, and then roll-rolled to prepare a sheet having an overall thickness of 150 ⁇ m. After cutting this sheet into a strip having a width of 43 mm and a length of 285 mm, a lead terminal of aluminum foil was attached to one end thereof by ultrasonic welding to obtain a positive electrode.
  • the negative electrode material paste was applied to both sides of the negative electrode current collector in a double stripe shape.
  • the width of the coating film of the linear negative electrode material paste was 300 mm, and the direction in which the coating film of the linear negative electrode material paste was stretched was made parallel to the longitudinal direction of the strip-shaped negative electrode current collector.
  • the negative electrode current collector coated with the negative electrode material paste was dried in a nitrogen atmosphere to volatilize the solvent, and then roll-rolled to prepare a sheet having an overall thickness of 150 ⁇ m. After cutting this sheet into a rectangular shape having a width of 43 mm and a length of 280 mm, a nickel foil lead terminal was attached to one end thereof by ultrasonic welding to form a negative electrode.
  • (D) Preparation of Lithium Ion Secondary Battery A polypropylene separator having a thickness of 25 ⁇ m was sandwiched between the positive electrode and the negative electrode manufactured as described above, and the whole of these was wound to obtain a wound body.
  • the wound body was housed in a cylindrical battery can, and the lead terminal of the negative electrode was spot welded to the bottom of the battery can.
  • the battery can is made of mild steel whose surface is nickel-plated.
  • the top lid made of insulating material was placed on the battery can, and after inserting the gasket, the lead terminal of the positive electrode and the safety valve made of aluminum were ultrasonically welded and connected. Then, after injecting a non-aqueous electrolyte solution consisting of propylene carbonate, diethyl carbonate, and ethylene carbonate into the battery can, a lid is attached to the safety valve, and a cylindrical sealed structure lithium ion battery with an outer diameter of 14 mm and a height of 50 mm is attached. I assembled the next battery.
  • each electrolytic copper foil manufactured in the above item (A) and each lithium ion secondary battery manufactured in the above item (D) were evaluated.
  • the evaluation method will be described below.
  • the foil thickness of each electrolytic copper foil produced in the above item (A) is as shown in Table 2.
  • the surface shape was measured at any 5 points on the end surface of the electrolytic precipitation, and shape analysis was performed at each of the 5 points to obtain the concave average volume VAV and the root mean square height Sq at each of the 5 points. Then, the average value of the results of the obtained five points was taken as the concave average volume VAV and the root mean square root height Sq of the electrolytic precipitation end surface of the electrolytic copper foil.
  • the shape analysis was performed by the VSI measurement method (vertical scanning interferometry) using a high resolution CCD camera (resolution 1280 x 960 pixels).
  • the conditions are that the light source is white light, the measurement magnification is 10 times, the measurement range is 477 ⁇ m ⁇ 357.8 ⁇ m, the threshold is 3%, and the filters are Terms Removal (Cylinder and Tilt) and Data Restore (Metado: legacy, iterations 5). After that, the Foiler Filter process was performed.
  • the concave average volume VAV was determined by Multiple Region Analysis. More specifically, "Region Finding Route” is By, Thrashold (s) is 0.5 ⁇ m, Minimum Resolution size is 100 pixels, Region Level is Valleys, Zero Level is Automatic, and Term Revolve is No. The value displayed in "Avg:” was adopted as the concave average volume VAV. Since Region Level is Valley and is calculated as a negative value, the calculated concave average volume VAV is corrected by an absolute value. The root mean square height Sq was calculated using S-parameters-height analysis with Remove Til as True. Table 2 shows the measurement results of the concave average volume VAV and the root mean square height Sq.
  • the electrolytic copper foil was cut into a rectangular shape having a width of 13.0 mm and a length of 152 mm, and this was used as a measurement sample. Then, a tensile test of the measurement sample was performed using a tensile tester 1122 manufactured by Instron, and the elongation rate and the tensile strength under normal conditions were measured. In this tensile test, the distance between chucks was 70 mm, the tensile speed was 50 mm / min, and other conditions were set based on the method specified in IPC-TM-650. The results are shown in Table 2.
  • the "normal state” means a state in which the electrolytic copper foil is placed at room temperature and humidity (for example, temperature 23 ⁇ 2 ° C., humidity 50 ⁇ 5% RH).
  • an electrolytic copper foil that breaks in less than 300 cycles is not suitable for use as a negative electrode current collector. It can be said that the electrolytic copper foil that breaks in 300 cycles or more and less than 500 cycles is suitable for the use of a negative electrode current collector. The electrolytic copper foil that does not break even after 500 cycles is particularly suitable for the use of the negative electrode current collector, and can improve the charge / discharge cycle characteristics of the lithium ion secondary battery.
  • the electrolytic copper foil has a foil thickness t of 10 or more and 20 or less, and VAV ⁇ t. Since it is more than 0 and 1000 or less and the E / t is 0.9 or more and 1.8 or less, the electrolytic copper foil is less likely to break even after repeated charging and discharging, and the charge and discharge cycle characteristics of the lithium ion secondary battery are excellent. Was there.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Cell Electrode Carriers And Collectors (AREA)
  • Secondary Cells (AREA)

Abstract

The present invention provides an electrolytic copper foil which is not susceptible to breaking. In this electrolytic copper foil, where t is the foil thickness (in units of µm), VAV is the recess average volume (in units of µm3), which is the average value of the volume of recesses formed in an electrolytic-deposition-completed surface, E is the elongation (in units of %) measured by pulling along a length direction, and the recess average volume VAV is measured using a white interference microscope, the foil thickness t is 10 to 20, the product VAV × t of the recess average volume VAV and the foil thickness t is more than 0 and no more than 1000, and the quotient E/t of the elongation E divided by the foil thickness t is 0.9 to 1.8.

Description

電解銅箔、リチウムイオン二次電池用負極、及びリチウムイオン二次電池Electrolytic copper foil, negative electrode for lithium ion secondary battery, and lithium ion secondary battery
　本発明は、電解銅箔、該電解銅箔を用いたリチウムイオン二次電池用負極、及び該リチウムイオン二次電池用負極を備えるリチウムイオン二次電池に関する。 The present invention relates to an electrolytic copper foil, a negative electrode for a lithium ion secondary battery using the electrolytic copper foil, and a lithium ion secondary battery including the negative electrode for the lithium ion secondary battery.
　リチウムイオン二次電池の負極集電体として銅箔が使用される場合があるが、リチウムイオン二次電池の充放電時の負極材の膨張収縮により、銅箔が破断する場合があった。また、密着している銅箔と負極材が充放電時に局所的に剥離し、剥離した部分に膨張収縮時の応力が集中するため、銅箔が破断する場合があった。
　特許文献１、２には、表面粗さを制御することによって負極材との密着性を向上させた、リチウムイオン二次電池の負極集電体として使用可能な電解銅箔が開示されている。特許文献３には、充放電時の負極材の膨張収縮に耐えることができる、耐屈曲性に優れた二次電池用電解銅箔が開示されている。特許文献４には、表面粗さ等を制御することによってたるみ、しわ、及び引き裂きを抑制した銅箔を用いて、優れた性能の二次電池を製造する技術が開示されている。
　近年リチウムイオン二次電池の研究が進んでおり、性能のさらなる向上が求められているため、充放電時に破断がより一層生じにくい銅箔が求められるようになっている。特許文献１～４に開示の電解銅箔は、機械的特性や負極材との密着性が不十分である場合があるため、リチウムイオン二次電池の充放電時に破断するおそれがあった。 A copper foil may be used as a negative electrode current collector of a lithium ion secondary battery, but the copper foil may break due to expansion and contraction of the negative electrode material during charging and discharging of the lithium ion secondary battery. In addition, the copper foil and the negative electrode material that are in close contact with each other are locally peeled off during charging and discharging, and stress during expansion and contraction is concentrated on the peeled portion, so that the copper foil may break.
Patent Documents 1 and 2 disclose electrolytic copper foils that can be used as a negative electrode current collector for a lithium ion secondary battery and have improved adhesion to a negative electrode material by controlling surface roughness. Patent Document 3 discloses an electrolytic copper foil for a secondary battery, which can withstand expansion and contraction of a negative electrode material during charging and discharging and has excellent bending resistance. Patent Document 4 discloses a technique for manufacturing a secondary battery having excellent performance by using a copper foil in which sagging, wrinkling, and tearing are suppressed by controlling surface roughness and the like.
In recent years, research on lithium-ion secondary batteries has progressed, and further improvement in performance is required. Therefore, copper foils that are less likely to break during charging and discharging are required. Since the electrolytic copper foils disclosed in Patent Documents 1 to 4 may have insufficient mechanical properties and adhesion to the negative electrode material, they may be broken during charging / discharging of the lithium ion secondary battery.
日本国特許公報　第６５８７７０１号Japanese Patent Gazette No. 6587701 国際公開第２０１８／２０７７８６号International Publication No. 2018/20786 日本国特許公開公報　２０２０年第５０２７２８号Japanese Patent Publication No. 2020 No. 502728 日本国特許公開公報　２０２０年第２６５６３号Japanese Patent Publication No. 2020 No. 26563
　本発明は、破断が生じにくい電解銅箔を提供することを課題とする。また、本発明は、充放電時に負極集電体に破断が生じにくいリチウムイオン二次電池用負極及びリチウムイオン二次電池を提供することを併せて課題とする。 An object of the present invention is to provide an electrolytic copper foil that is less likely to break. Another object of the present invention is to provide a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery in which the negative electrode current collector is less likely to break during charging and discharging.
　本発明の一態様に係る電解銅箔は、箔厚をｔ（単位はμｍ）、電解析出終了面に形成されている凹部の体積の平均値である凹部平均体積をＶＡＶ（単位はμｍ3）、長さ方向に沿って引っ張って測定した伸び率をＥ（単位は％）とし、凹部平均体積ＶＡＶが白色干渉顕微鏡を用いて測定したものであるとき、箔厚ｔが１０以上２０以下であり、凹部平均体積ＶＡＶと箔厚ｔの積であるＶＡＶ×ｔが０超過１０００以下であり、伸び率Ｅを箔厚ｔで除したＥ／ｔが０．９以上１．８以下であることを要旨とする。 In the electrolytic copper foil according to one aspect of the present invention, the foil thickness is t (unit: μm), and the concave average volume, which is the average value of the volumes of the concave portions formed on the electrolytic precipitation end surface, is VAV (unit: μm 3 ). ), The elongation rate measured by pulling along the length direction is E (unit is%), and when the concave average volume VAV is measured using a white interference microscope, the foil thickness t is 10 or more and 20 or less. Yes, VAV × t, which is the product of the concave average volume VAV and the foil thickness t, is more than 0 and 1000 or less, and E / t obtained by dividing the elongation rate E by the foil thickness t is 0.9 or more and 1.8 or less. Is the gist.
　また、本発明の他の態様に係るリチウムイオン二次電池用負極は、上記一態様に係る電解銅箔を備えることを要旨とする。
　さらに、本発明の他の態様に係るリチウムイオン二次電池は、上記他の態様に係るリチウムイオン二次電池用負極を備えることを要旨とする。 Further, it is a gist that the negative electrode for a lithium ion secondary battery according to another aspect of the present invention includes the electrolytic copper foil according to the above aspect.
Further, it is a gist that the lithium ion secondary battery according to another aspect of the present invention includes a negative electrode for a lithium ion secondary battery according to the other aspect.
　本発明の電解銅箔は、破断が生じにくい。また、本発明のリチウムイオン二次電池用負極及びリチウムイオン二次電池は、充放電時に負極集電体に破断が生じにくい。 The electrolytic copper foil of the present invention is less likely to break. Further, the negative electrode for a lithium ion secondary battery and the lithium ion secondary battery of the present invention are less likely to break in the negative electrode current collector during charging and discharging.
電解析出装置を用いて電解銅箔を製造する方法を説明する図である。It is a figure explaining the method of manufacturing the electrolytic copper foil using the electrolytic precipitation apparatus. 本実施形態に係る電解銅箔を説明する図であり、電解析出終了面に形成されている凹凸を示す白色干渉顕微鏡像である。It is a figure explaining the electrolytic copper foil which concerns on this embodiment, and is the white interference microscope image which shows the unevenness formed on the electrolytic precipitation end surface. 本実施形態に係る電解銅箔を説明する図であり、図２の白色干渉顕微鏡像内の１つのラインにおける電解析出終了面のプロファイルを示す図である。It is a figure explaining the electrolytic copper foil which concerns on this embodiment, and is the figure which shows the profile of the electrolytic precipitation end surface in one line in the white interference contrast microscope image of FIG.
　本発明の一実施形態について説明する。なお、以下に説明する実施形態は、本発明の一例を示したものである。また、本実施形態には種々の変更又は改良を加えることが可能であり、その様な変更又は改良を加えた形態も本発明に含まれ得る。
　本発明の一実施形態に係る電解銅箔は、箔厚をｔ（単位はμｍ）、電解析出終了面に形成されている凹部の体積の平均値である凹部平均体積（Ｖａｌｌｅｙｓ　Ａｖｅｒａｇｅ　Ｖｏｌｕｍｅ）をＶＡＶ（単位はμｍ3）、長さ方向に沿って引っ張って測定した伸び率をＥ（単位は％）とし、凹部平均体積ＶＡＶが白色干渉顕微鏡を用いて測定したものであるとき、箔厚ｔが１０以上２０以下であり、凹部平均体積ＶＡＶと箔厚ｔの積であるＶＡＶ×ｔが０超過１０００以下であり、伸び率Ｅを箔厚ｔで除したＥ／ｔが０．９以上１．８以下である。
　このような構成から、本実施形態の電解銅箔は、破断が生じにくい。 An embodiment of the present invention will be described. The embodiments described below show an example of the present invention. In addition, various changes or improvements can be added to the present embodiment, and the embodiment to which such changes or improvements are added can also be included in the present invention.
The electrolytic copper foil according to the embodiment of the present invention has a foil thickness of t (unit: μm) and a concave average volume (Valleys Average Volume) which is an average value of the volumes of the concave portions formed on the electrolytic precipitation end surface. VAV (unit: μm 3 ), elongation measured by pulling along the length direction is E (unit:%), and when the concave average volume VAV is measured using a white interference microscope, the foil thickness is t. Is 10 or more and 20 or less, VAV × t, which is the product of the average volume VAV of the recess and the foil thickness t, is more than 0 and 1000 or less, and E / t obtained by dividing the elongation rate E by the foil thickness t is 0.9 or more and 1 It is 0.8 or less.
Due to such a configuration, the electrolytic copper foil of the present embodiment is unlikely to break.
　本実施形態の電解銅箔は、リチウムイオン二次電池（主に円筒形のリチウムイオン二次電池）の負極集電体として使用することができる。すなわち、本実施形態のリチウムイオン二次電池用負極は、本実施形態の電解銅箔を備える。また、本実施形態のリチウムイオン二次電池は、本実施形態のリチウムイオン二次電池用負極を備える。
　本実施形態の電解銅箔が破断しにくいので、本実施形態のリチウムイオン二次電池用負極及びリチウムイオン二次電池は、充放電時に負極集電体に破断が生じにくい。 The electrolytic copper foil of the present embodiment can be used as a negative electrode current collector of a lithium ion secondary battery (mainly a cylindrical lithium ion secondary battery). That is, the negative electrode for the lithium ion secondary battery of the present embodiment includes the electrolytic copper foil of the present embodiment. Further, the lithium ion secondary battery of the present embodiment includes the negative electrode for the lithium ion secondary battery of the present embodiment.
Since the electrolytic copper foil of the present embodiment is hard to break, the negative electrode for the lithium ion secondary battery and the lithium ion secondary battery of the present embodiment are hard to break in the negative electrode current collector during charging and discharging.
　以下に、本実施形態の電解銅箔について、さらに詳細に説明する。
　本発明者は、鋭意検討の結果、高延伸性と電解析出終了面の平滑性（低プロファイル）との両方の特性を備える電解銅箔は、リチウムイオン二次電池の充放電時に負極材が膨張収縮しても破断が生じにくいことを見出した。 Hereinafter, the electrolytic copper foil of the present embodiment will be described in more detail.
As a result of diligent studies, the present inventor has found that the electrolytic copper foil having both high stretchability and smoothness (low profile) of the electrolytic precipitation end surface has a negative electrode material during charging and discharging of a lithium ion secondary battery. It was found that breakage is unlikely to occur even if it expands and contracts.
　電解銅箔が高延伸性であれば、負極材の膨張収縮に電解銅箔が追従可能であるため、破断が生じにくい。また、電解析出終了面に形成されている微細な凹部の体積の平均値である凹部平均体積ＶＡＶが小さく電解析出終了面が平滑であれば、密着している電解銅箔と負極材との密着力が密着面全体にわたって均一となるため、密着している電解銅箔と負極材との間に充放電時に局所的な剥離が生じることが抑制される。電解銅箔と負極材との間に局所的な剥離が生じると、剥離した部分に膨張収縮時の応力が集中するため、電解銅箔が破断しやすいが、本実施形態の電解銅箔は、局所的な剥離が生じにくいので、リチウムイオン二次電池の充放電時に破断が生じにくい。この点について、以下にさらに詳細に説明する。 If the electrolytic copper foil has high stretchability, the electrolytic copper foil can follow the expansion and contraction of the negative electrode material, so that breakage is unlikely to occur. Further, if the concave average volume VAV, which is the average value of the volumes of the fine recesses formed on the electrolytic precipitation end surface, is small and the electrolytic precipitation end surface is smooth, the electrolytic copper foil and the negative electrode material that are in close contact with each other are used. Since the adhesion force of the metal is uniform over the entire contact surface, it is possible to prevent local peeling between the electrolytic copper foil and the negative electrode material that are in close contact with each other during charging and discharging. When local peeling occurs between the electrolytic copper foil and the negative electrode material, the stress at the time of expansion and contraction is concentrated on the peeled portion, so that the electrolytic copper foil is easily broken. Since local peeling is unlikely to occur, breakage is unlikely to occur during charging and discharging of the lithium ion secondary battery. This point will be described in more detail below.
　従来は、電解銅箔の箔厚と引張による伸び率の関係が不明確であることが多く、同じ箔厚の電解銅箔でも伸び率等の特性にバラツキがあった。また、箔厚を大きくすると、電解めっき（電解銅箔を製造するための銅めっき）中の銅の析出メカニズムの変化によって、リチウムイオン二次電池の充放電時に電解銅箔の引張破断が早まるなどの問題もあった。 Conventionally, the relationship between the foil thickness of the electrolytic copper foil and the elongation rate due to tension is often unclear, and even with the electrolytic copper foil of the same foil thickness, the characteristics such as the elongation rate have varied. In addition, when the foil thickness is increased, the tensile breakage of the electrolytic copper foil is accelerated during charging and discharging of the lithium ion secondary battery due to the change in the copper precipitation mechanism during electrolytic plating (copper plating for producing electrolytic copper foil). There was also the problem of.
　本発明者は、鋭意検討の結果、電解めっきの電解条件を制御することによって、伸び率を箔厚で規格化した値（すなわちパラメータＥ／ｔ）が一定の領域に入ることを見出した。そして、こうして得られた電解銅箔を負極集電体として用いて製造したリチウムイオン二次電池は、充放電時に負極集電体に破断が生じにくいことを見出した。 As a result of diligent studies, the present inventor has found that the value obtained by normalizing the elongation rate by the foil thickness (that is, the parameter E / t) falls within a certain region by controlling the electrolytic conditions of the electrolytic plating. Then, it was found that the lithium ion secondary battery manufactured by using the electrolytic copper foil thus obtained as the negative electrode current collector is less likely to break in the negative electrode current collector during charging and discharging.
　また、従来は、Ｒａ、Ｒｚ等の表面粗さが小さい平滑な電解銅箔ほど、破断が起きにくいと考えられてきた。しかしながら、Ｒａ、Ｒｚ等の表面粗さは、電解銅箔の表面のうち任意の１つのラインにおけるプロファイルから算出されたものであり、一定の面積を有する領域内に存在する微細な凹部の大きさ等は、十分には表現されない数値である。 Further, conventionally, it has been considered that a smooth electrolytic copper foil having a small surface roughness such as Ra and Rz is less likely to break. However, the surface roughness of Ra, Rz, etc. is calculated from the profile in any one line on the surface of the electrolytic copper foil, and is the size of the fine recesses existing in the region having a certain area. Etc. are numerical values that are not sufficiently expressed.
　本発明者は、鋭意検討の結果、電解めっき時に、電解銅箔の厚さ方向に銅が結晶成長することにより、電解銅箔の表面に立方マイクロメートルスケールの微細な凹部が多数形成されることを見出した。そして、この凹部の体積が大きい場合には、リチウムイオン二次電池の充放電時に負極材が膨張収縮すると、この凹部が起点となって電解銅箔に破断が生じやすいことを見出した。この銅の結晶成長により形成される凹部は、箔厚に比例して、より大きくなる場合もあった。 As a result of diligent studies, the present inventor has found that, during electrolytic plating, copper crystal grows in the thickness direction of the electrolytic copper foil, so that a large number of cubic micrometer-scale fine recesses are formed on the surface of the electrolytic copper foil. I found. Then, it has been found that when the volume of the concave portion is large, when the negative electrode material expands and contracts during charging and discharging of the lithium ion secondary battery, the concave portion serves as a starting point and the electrolytic copper foil is likely to break. The recess formed by this copper crystal growth may become larger in proportion to the foil thickness.
　本発明者は、電解めっきの条件を制御することにより、電解析出終了面に形成されている凹部の体積の平均値である凹部平均体積ＶＡＶを小さくし、且つ、箔厚による凹部平均体積ＶＡＶへの影響を制御すれば、高い伸び率を有し破断が生じにくい電解銅箔が得られることを見出した。 By controlling the conditions of electroplating, the present inventor reduces the average recess volume VAV, which is the average value of the volumes of the recesses formed on the end surface of electrolytic precipitation, and reduces the average volume VAV of the recesses due to the foil thickness. It has been found that an electrolytic copper foil having a high elongation rate and less likely to break can be obtained by controlling the influence on the sheet.
　図２は、電解銅箔の電解析出終了面に形成されている凹凸を示す白色干渉顕微鏡像であり、色の濃淡で高さが表されている。図３は、電解銅箔の電解析出終了面のプロファイルを示す図であり、図２の白色干渉顕微鏡像内の１つのラインにおけるプロファイルである。ＩＳＯ２５１７８の規定に準拠して設定される高さ０μｍの横線よりも低い部分が、電解析出終了面に形成されている凹部である。 FIG. 2 is a white interference contrast microscope image showing the unevenness formed on the electrolytic precipitation end surface of the electrolytic copper foil, and the height is represented by the shade of color. FIG. 3 is a diagram showing a profile of the electrolytic precipitation end surface of the electrolytic copper foil, and is a profile in one line in the white interference contrast microscope image of FIG. The portion lower than the horizontal line having a height of 0 μm set in accordance with the ISO 25178 rule is the recess formed on the electrolytic precipitation end surface.
　凹部平均体積ＶＡＶは、電解銅箔の厚さ方向への銅の結晶成長を抑制することと、箔厚の増加との二つの因子の影響を受ける。よって、異なる箔厚の電解銅箔に関して、上記の結晶成長の抑制度合いを凹部平均体積ＶＡＶから類推する場合には、凹部平均体積ＶＡＶと箔厚ｔの積であるＶＡＶ×ｔを比較する必要がある。
　以上のことから、パラメータＶＡＶ×ｔとパラメータＥ／ｔの両方を規定することにより、破断が生じにくい目的の電解銅箔が得られることが分かった。 The recessed average volume VAV is affected by two factors: suppressing copper crystal growth in the thickness direction of the electrolytic copper foil and increasing the foil thickness. Therefore, when estimating the degree of suppression of crystal growth from the recessed average volume VAV for electrolytic copper foils having different foil thicknesses, it is necessary to compare VAV × t, which is the product of the recessed average volume VAV and the foil thickness t. be.
From the above, it was found that by defining both the parameter VAV × t and the parameter E / t, the target electrolytic copper foil that is less likely to break can be obtained.
〔箔厚ｔ〕
　箔厚ｔは、１０μｍ以上２０μｍ以下である必要があるが、１２μｍ以上２０μｍ以下であることが好ましい。箔厚ｔが上記範囲内であれば、電解銅箔の厚さ方向への結晶成長によって生じた大きな凹凸を埋めるべく、電解液中の有機添加剤が機能し、電解銅箔の厚さ方向への結晶成長を抑制する効果が得られる。その結果、電解析出終了面に形成されている凹部の体積の平均値である凹部平均体積ＶＡＶを小さくし、高い伸び率を有し破断が生じにくい電解銅箔が得られるという効果が奏される。 [Foil thickness t]
The foil thickness t needs to be 10 μm or more and 20 μm or less, but is preferably 12 μm or more and 20 μm or less. When the foil thickness t is within the above range, the organic additive in the electrolytic solution functions in order to fill the large unevenness caused by the crystal growth in the thickness direction of the electrolytic copper foil, and the organic additive in the electrolytic solution functions in the thickness direction of the electrolytic copper foil. The effect of suppressing the crystal growth of copper can be obtained. As a result, the effect of reducing the concave average volume VAV, which is the average value of the volumes of the concave portions formed on the end surface of the electrolytic precipitation, and obtaining an electrolytic copper foil having a high elongation rate and less likely to break is achieved. To.
　カソードへの通電開始時、すなわち箔厚ｔが０μｍから１０μｍ未満の領域では、電解銅箔の厚さ方向への結晶成長が優先され、凹部平均体積ＶＡＶが大きくなる傾向にあり、引張破断が早まる確率が高くなる。箔厚ｔが２０μｍを超える領域では、製箔に要する電解時間が長くなるので、有機添加剤の分解や消耗による影響を受けやすく、凹部平均体積ＶＡＶが飛びぬけて大きくなってしまう箇所が発生し、その結果、局所的な伸び率の低下が発生する確率が高まる。 At the start of energization of the cathode, that is, in the region where the foil thickness t is from 0 μm to less than 10 μm, crystal growth in the thickness direction of the electrolytic copper foil is prioritized, the concave average volume VAV tends to be large, and tensile fracture is accelerated. The probability is high. In the region where the foil thickness t exceeds 20 μm, the electrolysis time required for foil production becomes long, so that it is easily affected by the decomposition and consumption of organic additives, and there are places where the average volume VAV of the recesses becomes extremely large. As a result, there is an increased probability that a local decrease in elongation will occur.
〔ＶＡＶ×ｔ〕
　パラメータＶＡＶ×ｔは、０超過１０００以下である必要があるが、０超過４００以下であることが好ましい。パラメータＶＡＶ×ｔが上記範囲内であれば、電解銅箔の表面が平滑であるため、電解銅箔と負極材との密着力が密着面全体にわたって均一となりやすい。そのため、密着している電解銅箔と負極材との間に充放電時に局所的な剥離が生じることが抑制されるので、充放電時に破断が生じにくい。一方、パラメータＶＡＶ×ｔが上記範囲内であれば、電解銅箔と負極材との密着力は十分発現するので、充放電時に破断が生じにくい。 [VAV × t]
The parameter VAV × t needs to be 0 excess 1000 or less, but is preferably 0 excess 400 or less. When the parameter VAV × t is within the above range, the surface of the electrolytic copper foil is smooth, so that the adhesion between the electrolytic copper foil and the negative electrode material tends to be uniform over the entire contact surface. Therefore, local peeling between the electrolytic copper foil and the negative electrode material, which are in close contact with each other, is suppressed during charging / discharging, so that breakage is less likely to occur during charging / discharging. On the other hand, when the parameter VAV × t is within the above range, the adhesive force between the electrolytic copper foil and the negative electrode material is sufficiently exhibited, so that breakage is unlikely to occur during charging and discharging.
〔Ｅ／ｔ〕
　パラメータＥ／ｔは、０．９以上１．８以下である必要があるが、１．２以上１．７以下であることが好ましく、１．３以上１．６以下であることがより好ましい。パラメータＥ／ｔが上記範囲内であれば、電解銅箔が高い伸び率を有するため、充放電時に破断が生じにくい。 [E / t]
The parameter E / t needs to be 0.9 or more and 1.8 or less, but is preferably 1.2 or more and 1.7 or less, and more preferably 1.3 or more and 1.6 or less. When the parameter E / t is within the above range, the electrolytic copper foil has a high elongation rate, so that fracture is unlikely to occur during charging and discharging.
〔二乗平均平方根高さＳｑ〕
　本実施形態の電解銅箔の電解析出終了面の、白色干渉顕微鏡を用いて測定した二乗平均平方根高さＳｑは、０．１μｍ以上０．４μｍ以下であることが好ましく、０．１μｍ以上０．２５μｍ以下であることがより好ましい。 [Root mean square root height Sq]
The root mean square height Sq of the electrolytic precipitation end surface of the electrolytic copper foil of the present embodiment measured using a white interference microscope is preferably 0.1 μm or more and 0.4 μm or less, preferably 0.1 μm or more and 0. It is more preferably .25 μm or less.
　電解析出終了面の二乗平均平方根高さＳｑが上記範囲内であれば、アンカー効果により電解銅箔と負極材との密着力がより高くなりやすい。また、電解析出終了面の二乗平均平方根高さＳｑが上記範囲内であれば、電解析出終了面は十分に平滑であるため、密着している電解銅箔と負極材との密着力が密着面全体にわたって均一となる。よって、密着している電解銅箔と負極材との間に充放電時に局所的な剥離が生じることが抑制されるので、充放電時に破断がより生じにくい。 If the root mean square height Sq of the electrolytic precipitation end surface is within the above range, the adhesion between the electrolytic copper foil and the negative electrode material tends to be higher due to the anchor effect. Further, when the root mean square height Sq of the electrolytic precipitation end surface is within the above range, the electrolytic precipitation end surface is sufficiently smooth, so that the adhesion between the electrolytic copper foil and the negative electrode material that are in close contact with each other is strong. It becomes uniform over the entire contact surface. Therefore, local peeling between the electrolytic copper foil and the negative electrode material, which are in close contact with each other, is suppressed during charging / discharging, so that fracture is less likely to occur during charging / discharging.
〔引張強度〕
　本実施形態の電解銅箔は、長さ方向に沿って引っ張って測定した引張強度が３００ＭＰａ以上３８０ＭＰａ以下であることが好ましい。引張強度が上記範囲内であれば、電解銅箔がより破断しにくいことに加えて、負極材の膨張収縮に対する追従性がより優れている。 [Tensile strength]
The electrolytic copper foil of the present embodiment preferably has a tensile strength of 300 MPa or more and 380 MPa or less measured by pulling along the length direction. When the tensile strength is within the above range, the electrolytic copper foil is less likely to break, and the negative electrode material has more excellent followability to expansion and contraction.
　電解銅箔の引張強度は、長さ方向に沿って引っ張って測定したものであるが、本発明における電解銅箔の「長さ方向」とは、ＭＤ（Ｍａｃｈｉｎｅ　Ｄｉｒｅｃｔｉｏｎ）を意味し、例えば、電解銅箔の製造時に回転電極を使用して回転電極の表面にめっきにより銅箔を形成する場合であれば、回転電極の回転方向を意味する。 The tensile strength of the electrolytic copper foil is measured by pulling it along the length direction, and the "length direction" of the electrolytic copper foil in the present invention means MD (Machine Direction), for example, electrolysis. When the copper foil is formed by plating on the surface of the rotating electrode using the rotating electrode at the time of manufacturing the copper foil, it means the rotation direction of the rotating electrode.
　なお、本実施形態の電解銅箔は、リチウムイオン二次電池の負極集電体のみならず、他の用途にも使用することができる。例えば、本実施形態の電解銅箔は、プリント配線板用の銅箔としても好適に使用することができる。本実施形態の電解銅箔は、高延伸性と電解析出終了面の平滑性との両方の特性を備えているので、プリント配線板の製造時（例えば加熱プレス時）に、銅箔に貼り合わされるエポキシ樹脂等の樹脂が膨張収縮した場合でも、それに追従するため破断が生じにくい。 The electrolytic copper foil of the present embodiment can be used not only for the negative electrode current collector of the lithium ion secondary battery but also for other purposes. For example, the electrolytic copper foil of the present embodiment can be suitably used as a copper foil for a printed wiring board. Since the electrolytic copper foil of the present embodiment has both high stretchability and smoothness of the electrolytic precipitation end surface, it is attached to the copper foil at the time of manufacturing a printed wiring board (for example, at the time of heat pressing). Even when the resin such as the epoxy resin to be combined expands and contracts, it follows the expansion and contraction, so that it is unlikely to break.
〔電解銅箔の製造方法〕
　本実施形態の電解銅箔の製造方法の一例について以下に説明する。
　電解銅箔は、例えば、図１に示すような電解析出装置を用いて製造することができる。図１の電解析出装置は、白金族元素又はその酸化物を被覆したチタンからなる不溶性電極１２と、不溶性電極１２に対向して設けられたチタン製の回転電極１１と、を備えている。図１の電解析出装置を用いて銅めっきを行い、円柱状の回転電極１１の表面（円柱面）に銅を析出させて銅箔を形成し、回転電極１１の表面から銅箔を剥離することにより、本実施形態の電解銅箔を製造することができる。 [Manufacturing method of electrolytic copper foil]
An example of the method for manufacturing the electrolytic copper foil of the present embodiment will be described below.
The electrolytic copper foil can be produced, for example, by using an electrolytic precipitation device as shown in FIG. The electrolytic precipitation device of FIG. 1 includes an insoluble electrode 12 made of titanium coated with a platinum group element or an oxide thereof, and a titanium rotating electrode 11 provided facing the insoluble electrode 12. Copper plating is performed using the electrolytic precipitation device shown in FIG. 1, copper is deposited on the surface (columnar surface) of the columnar rotary electrode 11 to form a copper foil, and the copper foil is peeled off from the surface of the rotary electrode 11. Thereby, the electrolytic copper foil of the present embodiment can be manufactured.
　そして、銅めっきの際に電流密度、電解液の温度、電解液の組成（例えば、電解液中の銅イオン、硫酸、塩素イオン、添加剤の濃度）等の条件を制御することによって、電解銅箔の厚さ方向の銅の結晶成長を抑制することができる。その結果、凹部平均体積ＶＡＶが小さく、電解銅箔の箔厚による表面性状（例えば、凹部平均体積ＶＡＶ、二乗平均平方根高さＳｑ）の変化が小さく、且つ、高い伸び率を有する電解銅箔を得ることができる。 Then, during copper plating, electrolytic copper is controlled by controlling conditions such as current density, electrolytic solution temperature, and electrolytic solution composition (for example, concentration of copper ions, sulfuric acid, chlorine ions, and additives in the electrolytic solution). It is possible to suppress the growth of copper crystals in the thickness direction of the foil. As a result, the electrolytic copper foil having a small concave average volume VAV, a small change in the surface texture (for example, concave average volume VAV, root mean square height Sq) due to the foil thickness of the electrolytic copper foil, and having a high elongation rate can be obtained. Obtainable.
　銅めっきを行って電解銅箔を製造する方法の一例を、図１を参照しながらさらに詳細に説明する。銅めっきを行う場合には、回転電極１１をカソード、不溶性電極１２をアノードとして電流を印加する。不溶性電極１２としては、例えばＤＳＥ（Dimensionally Stable Electrode）電極（登録商標）を使用することができる。
　また、電解液１３としては、例えば、硫酸及び硫酸銅を含有する水溶液を使用することができる。電解液１３の銅濃度は、例えば５０～１５０ｇ／Ｌとすることができ、硫酸濃度は例えば２０～２００ｇ／Ｌとすることができる。 An example of a method of producing an electrolytic copper foil by performing copper plating will be described in more detail with reference to FIG. When copper plating is performed, a current is applied using the rotating electrode 11 as a cathode and the insoluble electrode 12 as an anode. As the insoluble electrode 12, for example, a DSE (Dimensionally Stable Electrode) electrode (registered trademark) can be used.
Further, as the electrolytic solution 13, for example, an aqueous solution containing sulfuric acid and copper sulfate can be used. The copper concentration of the electrolytic solution 13 can be, for example, 50 to 150 g / L, and the sulfuric acid concentration can be, for example, 20 to 200 g / L.
　図示しない電解液供給部から電解液１３を回転電極１１と不溶性電極１２の間に供給し（白抜き矢印を参照）、且つ、回転電極１１を点線矢印で示す方向に一定速度で回転させながら、回転電極１１と不溶性電極１２の間に直流電流を印加すると、回転電極１１の表面に銅が析出する。析出した銅を回転電極１１の表面から剥離し、図１において実線矢印で示すように引き上げて連続的に巻き取れば、電解銅箔１４が得られる。 While supplying the electrolytic solution 13 from the electrolytic solution supply unit (not shown) between the rotating electrode 11 and the insoluble electrode 12 (see the white arrow) and rotating the rotating electrode 11 in the direction indicated by the dotted arrow at a constant speed, When a DC current is applied between the rotating electrode 11 and the insoluble electrode 12, copper is deposited on the surface of the rotating electrode 11. The electrolytic copper foil 14 is obtained by peeling the precipitated copper from the surface of the rotating electrode 11, pulling it up as shown by the solid arrow in FIG. 1, and continuously winding it.
　銅めっきに用いる電解液１３には、電解銅箔の平滑化や機械的特性の制御の観点から、有機添加剤、無機添加剤等の添加剤を添加してもよい。添加剤を添加することにより、常態における電解銅箔の強度、伸び率、表面粗さを向上させたり、銅めっきにおける銅の結晶成長を抑制したりすることができる。添加剤は１種を単独で用いてもよいし、２種以上を併用してもよい。 Additives such as organic additives and inorganic additives may be added to the electrolytic solution 13 used for copper plating from the viewpoint of smoothing the electrolytic copper foil and controlling mechanical properties. By adding the additive, the strength, elongation, and surface roughness of the electrolytic copper foil under normal conditions can be improved, and the crystal growth of copper in copper plating can be suppressed. One type of additive may be used alone, or two or more types may be used in combination.
　有機添加剤としては、例えば、エチレンチオ尿素、ポリエチレングリコール、ヤヌスグリーンが挙げられる。
　無機添加剤としては、例えば、塩化物イオンの供給源として塩化ナトリウム（ＮａＣｌ）等の金属塩化物や塩化水素（ＨＣｌ）を用いることができる。 Examples of the organic additive include ethylenethiourea, polyethylene glycol, and Janus Green.
As the inorganic additive, for example, metal chloride such as sodium chloride (NaCl) or hydrogen chloride (HCl) can be used as a source of chloride ions.
　銅めっきに用いる電解液１３には、無機添加剤として塩化物イオン（塩素）を２０～５０ｍｇ／Ｌ添加することが好ましい。また、銅めっきに用いる電解液１３には、有機添加剤としてエチレンチオ尿素、ポリエチレングリコール及びヤヌスグリーンの少なくとも１種を、合計で３～３０ｍｇ／Ｌ添加することが好ましく、合計で３～１０ｍｇ／Ｌ添加することがより好ましい。 It is preferable to add 20 to 50 mg / L of chloride ion (chlorine) as an inorganic additive to the electrolytic solution 13 used for copper plating. Further, it is preferable to add at least one of ethylenethiourea, polyethylene glycol and Janus Green as an organic additive to the electrolytic solution 13 used for copper plating in a total of 3 to 30 mg / L, and a total of 3 to 10 mg / L. It is more preferable to add it.
　銅めっきの際には、銅の結晶が電解銅箔の厚さ方向に成長するおそれがあるが、エチレンチオ尿素、ポリエチレングリコール及びヤヌスグリーンの少なくとも１種を上記の範囲の濃度で電解液１３に添加すれば、電解銅箔の厚さ方向の銅の結晶成長を抑制する効果が大きくなる。 During copper plating, copper crystals may grow in the thickness direction of the electrolytic copper foil, but at least one of ethylenethiourea, polyethylene glycol and yanus green is added to the electrolytic solution 13 at a concentration in the above range. Then, the effect of suppressing the crystal growth of copper in the thickness direction of the electrolytic copper foil becomes large.
　銅めっきにおける電解条件は、例えば、下記の通りとすることができる。すなわち、電解液１３の液温は４５～６５℃、電流密度は２５～５０Ａ／ｄｍ2である。銅めっきの際には、アノード及びカソードの抵抗発熱によって電解液１３の温度が上昇し、有機添加剤が分解するおそれがあるため、電流密度を上記のような低い値に抑えることが好ましい。 The electrolytic conditions in copper plating can be, for example, as follows. That is, the liquid temperature of the electrolytic solution 13 is 45 to 65 ° C., and the current density is 25 to 50 A / dm 2 . At the time of copper plating, the temperature of the electrolytic solution 13 may rise due to the resistance heat generation of the anode and the cathode, and the organic additive may be decomposed. Therefore, it is preferable to suppress the current density to the above-mentioned low value.
　上記のようにして製造した電解銅箔の表面には、所望により表面処理を施してもよい。表面処理について以下に説明する。
　電解銅箔の表面には防錆処理を施してもよい。防錆処理としては、無機防錆処理と有機防錆処理が挙げられる。無機防錆処理としては、例えば、クロメート処理、めっき処理が挙げられ、該めっき処理によるめっき層上にクロメート処理を施してもよい。めっき処理としては、例えば、ニッケルめっき、ニッケル合金めっき、コバルトめっき、コバルト合金めっき、亜鉛めっき、亜鉛合金めっき、錫めっき、錫合金めっきが挙げられる。有機防錆処理としては、例えば、ベンゾトリアゾールを用いた表面処理が挙げられる。 If desired, the surface of the electrolytic copper foil produced as described above may be surface-treated. The surface treatment will be described below.
The surface of the electrolytic copper foil may be subjected to a rust preventive treatment. Examples of the rust preventive treatment include an inorganic rust preventive treatment and an organic rust preventive treatment. Examples of the inorganic rust preventive treatment include chromate treatment and plating treatment, and chromate treatment may be applied to the plating layer by the plating treatment. Examples of the plating treatment include nickel plating, nickel alloy plating, cobalt plating, cobalt alloy plating, zinc plating, zinc alloy plating, tin plating, and tin alloy plating. Examples of the organic rust preventive treatment include surface treatment using benzotriazole.
　防錆処理を施した表面に対し、さらにシランカップリング剤を用いた表面処理（シラン処理）を行ってもよい。シランカップリング剤を用いた表面処理により、電解銅箔の表面（負極材や樹脂との接合側の表面）に接着剤との親和力の強い官能基が付与されるので、電解銅箔と負極材や樹脂との密着性は一層向上し、電解銅箔の防錆性や吸湿耐熱性もさらに向上する。よって、このような電解銅箔は、リチウムイオン二次電池の負極集電体用又はプリント配線板用の電解銅箔として好適である。
　防錆処理やシランカップリング剤処理は、リチウムイオン二次電池の活物質と電解銅箔との密着強度を高め、リチウムイオン二次電池の充放電サイクル特性の低下を防ぐ役割を果たす。 The surface that has been subjected to the rust preventive treatment may be further subjected to surface treatment (silane treatment) using a silane coupling agent. By surface treatment using a silane coupling agent, a functional group having a strong affinity with an adhesive is imparted to the surface of the electrolytic copper foil (the surface on the bonding side with the negative electrode material or the resin), so that the electrolytic copper foil and the negative electrode material are provided. Adhesion with the resin and the resin is further improved, and the rust resistance and moisture absorption heat resistance of the electrolytic copper foil are further improved. Therefore, such an electrolytic copper foil is suitable as an electrolytic copper foil for a negative electrode current collector of a lithium ion secondary battery or a printed wiring board.
The rust preventive treatment and the silane coupling agent treatment increase the adhesion strength between the active material of the lithium ion secondary battery and the electrolytic copper foil, and play a role of preventing deterioration of the charge / discharge cycle characteristics of the lithium ion secondary battery.
　また、上記の防錆処理を施す前に、電解銅箔の表面に粗化処理を行ってもよい。粗化処理としては、例えば、めっき法、エッチング法等が好適に採用できる。めっき法は、未処理の電解銅箔の表面に凹凸を有する薄膜層を形成することにより表面を粗化する方法である。めっき法としては、電解めっき法、無電解めっき法が挙げられる。 Further, the surface of the electrolytic copper foil may be roughened before the above-mentioned rust preventive treatment is applied. As the roughening treatment, for example, a plating method, an etching method, or the like can be preferably adopted. The plating method is a method of roughening the surface by forming a thin film layer having irregularities on the surface of the untreated electrolytic copper foil. Examples of the plating method include an electrolytic plating method and an electroless plating method.
　めっき法による粗化処理としては、例えば、銅や銅合金などの銅を主成分とするめっき膜を、未処理の電解銅箔の表面に形成する方法が好ましい。エッチング法による粗化処理としては、例えば、物理的エッチングや化学的エッチングによる方法が好ましい。物理的エッチングとしては、サンドブラスト等でエッチングする方法が挙げられ、化学的エッチングとしては、無機酸又は有機酸と酸化剤と添加剤とを含有する処理液を用いて行なうエッチングが挙げられる。 As the roughening treatment by the plating method, for example, a method of forming a plating film containing copper as a main component such as copper or a copper alloy on the surface of an untreated electrolytic copper foil is preferable. As the roughening treatment by the etching method, for example, a method by physical etching or chemical etching is preferable. Examples of the physical etching include a method of etching by sandblasting and the like, and examples of the chemical etching include etching performed by using a treatment liquid containing an inorganic acid or an organic acid, an oxidizing agent and an additive.
〔実施例〕
　以下に実施例及び比較例を示して、本発明をさらに具体的に説明する。実施例１～１９及び比較例１、２の電解銅箔を製造し、これらの電解銅箔を用いて負極集電体をそれぞれ製造し、これらの負極集電体を用いてリチウムイオン二次電池をそれぞれ製造した。そして、電解銅箔及びリチウムイオン二次電池の種々の特性を評価した。電解銅箔及びリチウムイオン二次電池の製造方法と各種特性の評価方法について説明する。 〔Example〕
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The electrolytic copper foils of Examples 1 to 19 and Comparative Examples 1 and 2 are manufactured, negative electrode current collectors are manufactured using these electrolytic copper foils, and a lithium ion secondary battery is manufactured using these negative electrode current collectors. Was manufactured respectively. Then, various characteristics of the electrolytic copper foil and the lithium ion secondary battery were evaluated. A method for manufacturing an electrolytic copper foil and a lithium ion secondary battery and a method for evaluating various characteristics will be described.
（Ａ）銅めっき
　図１と同様の装置を用い前述と同様の操作で銅めっきを行い、回転電極の表面に銅を析出させた。そして、析出した銅を回転電極の表面から引き剥がし、連続的に巻き取ることにより、実施例及び比較例の電解銅箔を製造した（図１を参照）。銅めっき時の電解液の温度及び電流密度は、表１に示すとおりである。 (A) Copper plating Copper plating was performed by the same operation as described above using the same equipment as in FIG. 1, and copper was deposited on the surface of the rotating electrode. Then, the precipitated copper was peeled off from the surface of the rotating electrode and continuously wound to produce electrolytic copper foils of Examples and Comparative Examples (see FIG. 1). The temperature and current density of the electrolytic solution at the time of copper plating are as shown in Table 1.
　電解液には、硫酸、硫酸銅五水和物、及び添加剤を含有する水溶液を用いた。添加剤としては、エチレンチオ尿素、ポリエチレングリコール、及びヤヌスグリーンを用いた。硫酸、硫酸銅五水和物、及び各添加剤の濃度を表１に示す。硫酸銅五水和物の濃度は、銅としての濃度である。また、電解液中の塩素濃度を表１に示す。 An aqueous solution containing sulfuric acid, copper sulfate pentahydrate, and additives was used as the electrolytic solution. As additives, ethylene thiourea, polyethylene glycol, and Janus Green were used. Table 1 shows the concentrations of sulfuric acid, copper sulfate pentahydrate, and each additive. The concentration of copper sulfate pentahydrate is the concentration as copper. Table 1 shows the chlorine concentration in the electrolytic solution.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（Ｂ）正極の製造
　コバルト酸リチウム（ＬｉＣｏＯ2）粉末９０質量％、黒鉛粉末７質量％、ポリフッ化ビニリデン粉末３質量％を混合したものに、溶剤としてＮ－メチル－２－ピロリドンとエタノールを添加し混練して、正極材ペーストを調製した。この正極材ペーストをアルミニウム箔の上に厚さ１５μｍで均一に塗着した。正極材ペーストを塗着したアルミニウム箔を窒素雰囲気中で乾燥して溶剤を揮散させた後に、ロール圧延を行って、全体の厚さが１５０μｍであるシートを作製した。このシートを幅４３ｍｍ、長さ２８５ｍｍの帯状に切断した後に、その一端にアルミ箔のリード端子を超音波溶接で取り付け、正極とした。 (B) Production of positive electrode N-methyl-2-pyrrolidone and ethanol are added as solvents to a mixture of 90% by mass of lithium cobalt oxide (LiCoO 2 ) powder, 7% by mass of graphite powder, and 3% by mass of polyvinylidene fluoride powder. The positive electrode material paste was prepared by kneading. This positive electrode material paste was uniformly applied onto the aluminum foil with a thickness of 15 μm. The aluminum foil coated with the positive electrode material paste was dried in a nitrogen atmosphere to volatilize the solvent, and then roll-rolled to prepare a sheet having an overall thickness of 150 μm. After cutting this sheet into a strip having a width of 43 mm and a length of 285 mm, a lead terminal of aluminum foil was attached to one end thereof by ultrasonic welding to obtain a positive electrode.
（Ｃ）負極の製造
　平均粒径１０μｍの天然黒鉛粉末９０質量％とポリフッ化ビニリデン粉末１０質量％を混合したものに、溶剤としてＮ－メチル－２－ピロリドンとエタノールを添加し混練して、負極材ペーストを調製した。
　上記（Ａ）項で製造した各電解銅箔を幅７２０ｍｍの帯状に切断して、負極集電体とした。このとき、電解銅箔の幅方向が、切断して得られる帯状の負極集電体の幅方向と一致するようにした。 (C) Production of Negative Electrode N-methyl-2-pyrrolidone and ethanol are added and kneaded as a solvent to a mixture of 90% by mass of natural graphite powder having an average particle size of 10 μm and 10% by mass of polyvinylidene fluoride powder, and the negative electrode is used. A wood paste was prepared.
Each electrolytic copper foil produced in the above item (A) was cut into a strip having a width of 720 mm to obtain a negative electrode current collector. At this time, the width direction of the electrolytic copper foil was made to coincide with the width direction of the strip-shaped negative electrode current collector obtained by cutting.
　次に、負極集電体の両面に、負極材ペーストを二重ストライプ状に塗着した。線状の負極材ペーストの塗膜の幅は３００ｍｍで、線状の負極材ペーストの塗膜が伸びる方向が帯状の負極集電体の長手方向と平行になるようにした。
　負極材ペーストを塗着した負極集電体を窒素雰囲気中で乾燥して溶剤を揮散させた後に、ロール圧延を行って、全体の厚さが１５０μｍであるシートを作製した。このシートを幅４３ｍｍ、長さ２８０ｍｍの長方形状に切断した後に、その一端にニッケル箔のリード端子を超音波溶接で取り付け、負極とした。 Next, the negative electrode material paste was applied to both sides of the negative electrode current collector in a double stripe shape. The width of the coating film of the linear negative electrode material paste was 300 mm, and the direction in which the coating film of the linear negative electrode material paste was stretched was made parallel to the longitudinal direction of the strip-shaped negative electrode current collector.
The negative electrode current collector coated with the negative electrode material paste was dried in a nitrogen atmosphere to volatilize the solvent, and then roll-rolled to prepare a sheet having an overall thickness of 150 μm. After cutting this sheet into a rectangular shape having a width of 43 mm and a length of 280 mm, a nickel foil lead terminal was attached to one end thereof by ultrasonic welding to form a negative electrode.
（Ｄ）リチウムイオン二次電池の作製
　上記のように製造した正極と負極の間に、厚さ２５μｍのポリプロピレン製のセパレータを挟み、これら全体を巻いて捲回体を得た。この捲回体を円筒形の電池缶に収容して、負極のリード端子を電池缶の底部にスポット溶接した。なお、電池缶は、表面にニッケルめっきを施した軟鋼で形成されている。 (D) Preparation of Lithium Ion Secondary Battery A polypropylene separator having a thickness of 25 μm was sandwiched between the positive electrode and the negative electrode manufactured as described above, and the whole of these was wound to obtain a wound body. The wound body was housed in a cylindrical battery can, and the lead terminal of the negative electrode was spot welded to the bottom of the battery can. The battery can is made of mild steel whose surface is nickel-plated.
　次に、絶縁材製の上蓋を電池缶の上に置き、ガスケットを挿入した後に正極のリード端子とアルミニウム製の安全弁とを超音波溶接して接続した。そして、炭酸プロピレンと炭酸ジエチルと炭酸エチレンからなる非水電解液を電池缶の中に注入した後に、安全弁に上蓋を取り付けて、外径１４ｍｍ、高さ５０ｍｍの円筒形の密閉構造型リチウムイオン二次電池を組み立てた。 Next, the top lid made of insulating material was placed on the battery can, and after inserting the gasket, the lead terminal of the positive electrode and the safety valve made of aluminum were ultrasonically welded and connected. Then, after injecting a non-aqueous electrolyte solution consisting of propylene carbonate, diethyl carbonate, and ethylene carbonate into the battery can, a lid is attached to the safety valve, and a cylindrical sealed structure lithium ion battery with an outer diameter of 14 mm and a height of 50 mm is attached. I assembled the next battery.
　次に、上記（Ａ）項で製造した各電解銅箔と、上記（Ｄ）項で製造した各リチウムイオン二次電池の各種特性を評価した。評価方法を以下に説明する。なお、上記（Ａ）項で製造した各電解銅箔の箔厚は、表２に記載の通りである。 Next, various characteristics of each electrolytic copper foil manufactured in the above item (A) and each lithium ion secondary battery manufactured in the above item (D) were evaluated. The evaluation method will be described below. The foil thickness of each electrolytic copper foil produced in the above item (A) is as shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
〔電解銅箔の電解析出終了面の凹部平均体積ＶＡＶ及び二乗平均平方根高さＳｑ〕
　以下に述べる凹部平均体積ＶＡＶ及び二乗平均平方根高さＳｑの測定方法は、ＩＳＯ２５１７８に記載された内容を参考にして決定した方法である。ＢＲＵＫＥＲ社製の白色光干渉型光学顕微鏡Ｗｙｋｏ　ＣｏｎｔｏｕｒＧＴ－Ｋを用いて、電解銅箔の電解析出終了面の表面形状を測定し、形状解析を行って、凹部平均体積ＶＡＶ及び二乗平均平方根高さＳｑを求めた。表面形状の測定は、電解析出終了面の任意の５箇所で行い、５箇所それぞれ形状解析を行って、５箇所それぞれ凹部平均体積ＶＡＶ及び二乗平均平方根高さＳｑを求めた。そして、得られた５箇所の結果の平均値を電解銅箔の電解析出終了面の凹部平均体積ＶＡＶ及び二乗平均平方根高さＳｑとした。 [Average volume VAV of recesses on the end surface of electrolytic precipitation of electrolytic copper foil and root mean square height Sq]
The method for measuring the concave average volume VAV and the root mean square height Sq described below is a method determined with reference to the contents described in ISO25178. Using a white light interference type optical microscope WykoContourGT-K manufactured by BRUKER, the surface shape of the electrolytic precipitation end surface of the electrolytic copper foil was measured, and shape analysis was performed to perform concave average volume VAV and root mean square root height. Sq was calculated. The surface shape was measured at any 5 points on the end surface of the electrolytic precipitation, and shape analysis was performed at each of the 5 points to obtain the concave average volume VAV and the root mean square height Sq at each of the 5 points. Then, the average value of the results of the obtained five points was taken as the concave average volume VAV and the root mean square root height Sq of the electrolytic precipitation end surface of the electrolytic copper foil.
　形状解析は、ハイレゾリューションＣＣＤカメラ（解像度１２８０×９６０ピクセル）を使用してＶＳＩ測定方式（垂直走査型干渉法）で行った。条件は、光源が白色光、測定倍率が１０倍、測定範囲が４７７μｍ×３５７．８μｍ、Ｔｈｒｅｓｈｏｌｄが３％とし、Ｔｅｒｍｓ　Ｒｅｍｏｖａｌ（Ｃｙｌｉｎｄｅｒ　ａｎｄ　Ｔｉｌｔ）、Ｄａｔａ　Ｒｅｓｔｏｒｅ（Ｍｅｔｈｏｄ：ｌｅｇａｃｙ、ｉｔｅｒａｔｉｏｎｓ　５）のフィルタ処理をした後に、Ｆｏｕｒｉｅｒ　Ｆｉｌｔｅｒ処理を行なった。 The shape analysis was performed by the VSI measurement method (vertical scanning interferometry) using a high resolution CCD camera (resolution 1280 x 960 pixels). The conditions are that the light source is white light, the measurement magnification is 10 times, the measurement range is 477 μm × 357.8 μm, the threshold is 3%, and the filters are Terms Removal (Cylinder and Tilt) and Data Restore (Metado: legacy, iterations 5). After that, the Foiler Filter process was performed.
　Ｆｏｕｒｉｅｒ　Ｆｉｌｔｅｒ処理は、ｆｏｕｒｉｅｒ　ｆｉｌｔｅｒｉｎｇとしてＨｉｇｈ　Ｆｒｅｑ　Ｐａｓｓを用い、Ｆｏｕｒｉｅｒ　Ｆｉｌｔｅｒ　ＷｉｎｄｏｗにＧａｕｓｓｉａｎを用い、Ｆｒｅｑｕｅｎｃｙ　ＣｕｔｏｆｆでＨｉｇｈ　Ｃｕｔｏｆｆを１２．５ｍｍ-1とした。
　さらに、Ｓｔａｔｉｓｔｉｃ　Ｆｉｌｔｅｒ（Ｆｉｌｔｅｒ　Ｓｉｚｅ：３、Ｆｉｌｔｅｒ　Ｔｙｐｅ：Ｍｅｄｉａｎ）処理を行った。 For the Fourier Filter treatment, High Freq Pass was used as the Fourier filtering, Gaussian was used as the Fourier Filter Window, and the High Frequency was set to 12.5 mm -1 in the Frequency Cutoff.
Further, a Statistic Filter (Statistic Size: 3, Filter Type: Median) treatment was performed.
　凹部平均体積ＶＡＶは、Ｍｕｌｔｉｐｌｅ　Ｒｅｇｉｏｎ　Ａｎａｌｙｓｉｓにより求めた。詳述すると、「Ｒｅｇｉｏｎ　Ｆｉｎｄｉｎｇ　Ｒｏｕｔｉｎｅ」をＢｙ、Ｔｈｒｅｓｈｏｌｄ（ｓ）を０．５μｍ、Ｍｉｎｉｍｕｍ　Ｒｅｓｉｏｎ　ｓｉｚｅを１００ピクセル、Ｒｅｇｉｏｎ　ＬｅｖｅｌをＶａｌｌｅｙｓ、Ｚｅｒｏ　ＬｅｖｅｌをＡｕｔｏｍａｔｉｃ、Ｔｅｒｍ　ＲｅｍｏｖａｌをＮｏｎｅとし、算出されるＶｏｌｕｍｅ値の「Ａｖｇ：」に表示される値を凹部平均体積ＶＡＶとして採用した。なお、Ｒｅｇｉｏｎ　ＬｅｖｅｌがＶａｌｌｅｙであり、負の値として算出されるので、算出された凹部平均体積ＶＡＶについては、絶対値補正を実施した。
　二乗平均平方根高さＳｑは、Ｓ　ｐａｒａｍｅｔｅｒｓ－ｈｅｉｇｈｔ解析でＲｅｍｏｖｅ　ＴｉｌｔをＴｒｕｅとして算出した。
　凹部平均体積ＶＡＶ及び二乗平均平方根高さＳｑの測定結果を、表２に示す。 The concave average volume VAV was determined by Multiple Region Analysis. More specifically, "Region Finding Route" is By, Thrashold (s) is 0.5 μm, Minimum Resolution size is 100 pixels, Region Level is Valleys, Zero Level is Automatic, and Term Revolve is No. The value displayed in "Avg:" was adopted as the concave average volume VAV. Since Region Level is Valley and is calculated as a negative value, the calculated concave average volume VAV is corrected by an absolute value.
The root mean square height Sq was calculated using S-parameters-height analysis with Remove Til as True.
Table 2 shows the measurement results of the concave average volume VAV and the root mean square height Sq.
〔電解銅箔の伸び率Ｅ及び引張強度〕
　電解銅箔を幅１３．０ｍｍ、長さ１５２ｍｍの長方形状に切断して、これを測定用サンプルとした。そして、インストロン社製の引張試験機１１２２型を使用して、測定用サンプルの引張試験を行い、常態における伸び率と引張強度を測定した。この引張試験においては、チャック間距離を７０ｍｍ、引張速度を５０ｍｍ／ｍｉｎとし、その他の条件をＩＰＣ－ＴＭ－６５０に規定された方法に基づいて設定した。結果を表２に示す。なお、本発明において「常態」とは、電解銅箔が常温常湿（例えば温度２３±２℃、湿度５０±５％ＲＨ）におかれた状態のことを意味する。 [Elongation rate E and tensile strength of electrolytic copper foil]
The electrolytic copper foil was cut into a rectangular shape having a width of 13.0 mm and a length of 152 mm, and this was used as a measurement sample. Then, a tensile test of the measurement sample was performed using a tensile tester 1122 manufactured by Instron, and the elongation rate and the tensile strength under normal conditions were measured. In this tensile test, the distance between chucks was 70 mm, the tensile speed was 50 mm / min, and other conditions were set based on the method specified in IPC-TM-650. The results are shown in Table 2. In the present invention, the "normal state" means a state in which the electrolytic copper foil is placed at room temperature and humidity (for example, temperature 23 ± 2 ° C., humidity 50 ± 5% RH).
〔リチウムイオン二次電池の充放電サイクル特性の評価〕
　リチウムイオン二次電池に対して、充電電流１００ｍＡで４．２Ｖになるまで充電した後に、放電電流１００ｍＡで２．４Ｖになるまで放電するサイクルを１サイクルとする充放電サイクル試験を行った。このサイクルを繰り返した後に、リチウムイオン二次電池を分解し電解銅箔の破断の有無を調べた。結果を表２に示す。
　表２においては、５００サイクル以上でも破断が見られなかった場合は「Ａ」、３００サイクル以上５００サイクル未満で破断した場合は「Ｂ」、３００サイクル未満で破断した場合は「Ｃ」で示してある。 [Evaluation of charge / discharge cycle characteristics of lithium-ion secondary batteries]
A charge / discharge cycle test was conducted in which a lithium ion secondary battery was charged to 4.2 V at a charge current of 100 mA and then discharged to 2.4 V at a discharge current of 100 mA as one cycle. After repeating this cycle, the lithium ion secondary battery was disassembled and the presence or absence of breakage of the electrolytic copper foil was examined. The results are shown in Table 2.
In Table 2, when no break is observed even after 500 cycles, it is indicated by "A", when it is broken in 300 cycles or more and less than 500 cycles, it is indicated by "B", and when it is broken in less than 300 cycles, it is indicated by "C". be.
　３００サイクル未満で破断する電解銅箔は、負極集電体の用途には適さないと言える。３００サイクル以上５００サイクル未満で破断する電解銅箔は、負極集電体の用途に適していると言える。５００サイクル以上でも破断しない電解銅箔は、負極集電体の用途に特に適しており、リチウムイオン二次電池の充放電サイクル特性を良好とすることができる。 It can be said that an electrolytic copper foil that breaks in less than 300 cycles is not suitable for use as a negative electrode current collector. It can be said that the electrolytic copper foil that breaks in 300 cycles or more and less than 500 cycles is suitable for the use of a negative electrode current collector. The electrolytic copper foil that does not break even after 500 cycles is particularly suitable for the use of the negative electrode current collector, and can improve the charge / discharge cycle characteristics of the lithium ion secondary battery.
　表２から分かるように、実施例１～１９の電解銅箔を負極集電体として用いたリチウムイオン二次電池は、電解銅箔の箔厚ｔが１０以上２０以下であり、ＶＡＶ×ｔが０超過１０００以下であり、Ｅ／ｔが０．９以上１．８以下であるため、充放電を繰り返しても電解銅箔に破断が生じにくく、リチウムイオン二次電池の充放電サイクル特性が優れていた。 As can be seen from Table 2, in the lithium ion secondary batteries using the electrolytic copper foils of Examples 1 to 19 as the negative electrode current collector, the electrolytic copper foil has a foil thickness t of 10 or more and 20 or less, and VAV × t. Since it is more than 0 and 1000 or less and the E / t is 0.9 or more and 1.8 or less, the electrolytic copper foil is less likely to break even after repeated charging and discharging, and the charge and discharge cycle characteristics of the lithium ion secondary battery are excellent. Was there.
　　１１・・・回転電極
　　１２・・・不溶性電極
　　１３・・・電解液
　　１４・・・電解銅箔 11 ... Rotating electrode 12 ... Insoluble electrode 13 ... Electrolytic solution 14 ... Electrolytic copper foil

Claims (10)

  1. 　箔厚をｔ（単位はμｍ）、電解析出終了面に形成されている凹部の体積の平均値である凹部平均体積をＶＡＶ（単位はμｍ3）、長さ方向に沿って引っ張って測定した伸び率をＥ（単位は％）とし、凹部平均体積ＶＡＶが白色干渉顕微鏡を用いて測定したものであるとき、箔厚ｔが１０以上２０以下であり、凹部平均体積ＶＡＶと箔厚ｔの積であるＶＡＶ×ｔが０超過１０００以下であり、伸び率Ｅを箔厚ｔで除したＥ／ｔが０．９以上１．８以下である電解銅箔。 The foil thickness was t (unit: μm), and the average volume of the recesses formed on the electrolytic precipitation end surface was measured by pulling along the length direction with VAV (unit: μm 3 ). When the elongation rate is E (unit is%) and the concave average volume VAV is measured using a white interference microscope, the foil thickness t is 10 or more and 20 or less, and the product of the concave average volume VAV and the foil thickness t. A electrolytic copper foil having a VAV × t of more than 0 and 1000 or less, and an E / t obtained by dividing the elongation rate E by the foil thickness t of 0.9 or more and 1.8 or less.
  2. 　凹部平均体積ＶＡＶと箔厚ｔの積であるＶＡＶ×ｔが０超過４００以下であり、伸び率Ｅを箔厚ｔで除したＥ／ｔが１．２以上１．７以下である請求項１に記載の電解銅箔。 Claim 1 that VAV × t, which is the product of the average volume VAV of the recess and the foil thickness t, is more than 0 and 400 or less, and E / t obtained by dividing the elongation ratio E by the foil thickness t is 1.2 or more and 1.7 or less. The electrolytic copper foil described in.
  3. 　伸び率Ｅを箔厚ｔで除したＥ／ｔが１．３以上１．６以下である請求項１又は請求項２に記載の電解銅箔。 The electrolytic copper foil according to claim 1 or 2, wherein E / t obtained by dividing the elongation rate E by the foil thickness t is 1.3 or more and 1.6 or less.
  4. 　白色干渉顕微鏡を用いて測定した前記電解析出終了面の二乗平均平方根高さＳｑが０．１μｍ以上０．４μｍ以下である請求項１～３のいずれか一項に記載の電解銅箔。 The electrolytic copper foil according to any one of claims 1 to 3, wherein the root mean square height Sq of the electrolytic precipitation end surface measured using a white interference microscope is 0.1 μm or more and 0.4 μm or less.
  5. 　白色干渉顕微鏡を用いて測定した前記電解析出終了面の二乗平均平方根高さＳｑが０．１μｍ以上０．２５μｍ以下である請求項１～３のいずれか一項に記載の電解銅箔。 The electrolytic copper foil according to any one of claims 1 to 3, wherein the root mean square height Sq of the electrolytic precipitation end surface measured using a white interference microscope is 0.1 μm or more and 0.25 μm or less.
  6. 　長さ方向に沿って引っ張って測定した引張強度が３００ＭＰａ以上３８０ＭＰａ以下である請求項１～５のいずれか一項に記載の電解銅箔。 The electrolytic copper foil according to any one of claims 1 to 5, wherein the tensile strength measured by pulling along the length direction is 300 MPa or more and 380 MPa or less.
  7. 　リチウムイオン二次電池の負極集電体用である請求項１～６のいずれか一項に記載の電解銅箔。 The electrolytic copper foil according to any one of claims 1 to 6, which is for a negative electrode current collector of a lithium ion secondary battery.
  8. 　プリント配線板用である請求項１～６のいずれか一項に記載の電解銅箔。 The electrolytic copper foil according to any one of claims 1 to 6 for a printed wiring board.
  9. 　請求項１～７のいずれか一項に記載の電解銅箔を備えるリチウムイオン二次電池用負極。 A negative electrode for a lithium ion secondary battery provided with the electrolytic copper foil according to any one of claims 1 to 7.
  10. 　請求項９に記載のリチウムイオン二次電池用負極を備えるリチウムイオン二次電池。 A lithium ion secondary battery comprising the negative electrode for the lithium ion secondary battery according to claim 9.
PCT/JP2021/035367 2020-10-22 2021-09-27 Electrolytic copper foil, negative electrode for lithium ion secondary cell, and lithium ion secondary cell WO2022085371A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2022515789A JPWO2022085371A1 (en) 2020-10-22 2021-09-27

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2020177603 2020-10-22
JP2020-177603 2020-10-22

Publications (1)

Publication Number Publication Date
WO2022085371A1 true WO2022085371A1 (en) 2022-04-28

Family

ID=81291236

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2021/035367 WO2022085371A1 (en) 2020-10-22 2021-09-27 Electrolytic copper foil, negative electrode for lithium ion secondary cell, and lithium ion secondary cell

Country Status (3)

Country Link
JP (1) JPWO2022085371A1 (en)
TW (1) TW202223163A (en)
WO (1) WO2022085371A1 (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004162144A (en) * 2002-11-15 2004-06-10 Nippon Denkai Kk Method for manufacturing electrolytic copper foil
JP2004263289A (en) * 2002-10-25 2004-09-24 Fukuda Metal Foil & Powder Co Ltd Low rough surface electrolytic copper foil, and production method therefor
JP2018014332A (en) * 2015-10-15 2018-01-25 長春石油化學股▲分▼有限公司 Copper foil showing slack resistance
WO2019163962A1 (en) * 2018-02-23 2019-08-29 古河電気工業株式会社 Electrolytic copper foil, lithium-ion secondary cell negative electrode using electrolytic copper foil, lithium-ion secondary cell, copper-clad laminate and printed wiring board
JP2020125540A (en) * 2019-02-01 2020-08-20 長春石油化學股▲分▼有限公司 Copper foil for negative electrode current collector of lithium ion secondary battery
JP2020147844A (en) * 2019-03-14 2020-09-17 長春石油化學股▲分▼有限公司 Electrolytic copper foil having anti-copper burr characteristics

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004263289A (en) * 2002-10-25 2004-09-24 Fukuda Metal Foil & Powder Co Ltd Low rough surface electrolytic copper foil, and production method therefor
JP2004162144A (en) * 2002-11-15 2004-06-10 Nippon Denkai Kk Method for manufacturing electrolytic copper foil
JP2018014332A (en) * 2015-10-15 2018-01-25 長春石油化學股▲分▼有限公司 Copper foil showing slack resistance
WO2019163962A1 (en) * 2018-02-23 2019-08-29 古河電気工業株式会社 Electrolytic copper foil, lithium-ion secondary cell negative electrode using electrolytic copper foil, lithium-ion secondary cell, copper-clad laminate and printed wiring board
JP2020125540A (en) * 2019-02-01 2020-08-20 長春石油化學股▲分▼有限公司 Copper foil for negative electrode current collector of lithium ion secondary battery
JP2020147844A (en) * 2019-03-14 2020-09-17 長春石油化學股▲分▼有限公司 Electrolytic copper foil having anti-copper burr characteristics

Also Published As

Publication number Publication date
TW202223163A (en) 2022-06-16
JPWO2022085371A1 (en) 2022-04-28

Similar Documents

Publication Publication Date Title
TWI466367B (en) A lithium ion secondary battery, an electrode for the secondary battery, an electrode for an electrolytic copper foil
JP6837409B2 (en) Copper foil with uniform thickness and its manufacturing method
JP6190980B2 (en) Electrolytic copper foil and various products using the electrolytic copper foil
JP3850155B2 (en) Electrolytic copper foil, copper foil for current collector of secondary battery and secondary battery
TWI526578B (en) An electrolytic copper foil and a lithium ion secondary battery using the electrolytic copper foil as a current collector
TWI539033B (en) Electrolytic copper foil and its preparation method
EP3376574B1 (en) Method for manufacturing an electrolytic copper foil, electrolytic copper foil obtainable by the method, electrode comprising the same, and secondary battery comprising the same
WO2010110205A1 (en) Lithium ion secondary battery, electrode for the battery, and electrodeposited copper foil for the electrode for the battery
JP7008128B2 (en) Electrolyzed copper foil, its manufacturing method and cathode for high-capacity Li secondary batteries including it
JP2020147844A (en) Electrolytic copper foil having anti-copper burr characteristics
KR102646185B1 (en) Copper foil having improved adhesion, electrode comprisng the same, secondary battery comprising the same and method for manufacturing the same
WO2022054597A1 (en) Electrolytic copper foil, negative electrode for lithium ion secondary batteries, and lithium ion secondary battery
JP5981165B2 (en) Copper foil, negative electrode of secondary battery, secondary battery, and printed circuit board
JP2020057581A (en) Copper foil for current collector of lithium secondary battery and negative electrode including the same
WO2022085371A1 (en) Electrolytic copper foil, negative electrode for lithium ion secondary cell, and lithium ion secondary cell
KR101851515B1 (en) Electrolytic copper foil, lithium ion secondary battery using the electrolytic copper foil
KR102302184B1 (en) Copper Film With Dimensional Stability And Texture Stability At High Temperature, And Manufacturing Methods Thereof
JP3850321B2 (en) Secondary battery
JP4460058B2 (en) Copper foil for lithium secondary battery electrode and method for producing the same, electrode for lithium secondary battery and lithium secondary battery using the copper foil
EP3608447B1 (en) Copper foil with minimized bagginess, wrinkle and tear, electrode including the same, secondary battery including the same and method for manufacturing the same
JP4460055B2 (en) Copper foil for lithium secondary battery electrode and method for producing the same, electrode for lithium secondary battery and lithium secondary battery using the copper foil
CN115198319B (en) Electrolytic copper foil, electrode comprising same and lithium ion battery
EP3608448B1 (en) Copper foil with minimized bagginess and tear, electrode comprising the same, secondary battery comprising the same and method for manufacturing the same
CN110880601B (en) Copper foil with minimized swelling and tearing, electrode including the same, secondary battery including the same, and method of manufacturing the same
KR102518398B1 (en) Copper foil with high stability, electrode comprisng the same, secondary battery comprising the same and method for manufacturing the same

Legal Events

Date Code Title Description
ENP Entry into the national phase

Ref document number: 2022515789

Country of ref document: JP

Kind code of ref document: A

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21882512

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21882512

Country of ref document: EP

Kind code of ref document: A1