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WO2008001537A1 - Électrode négative pour accumulateur à électrolyte polymère - Google Patents

Électrode négative pour accumulateur à électrolyte polymère Download PDF

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Publication number
WO2008001537A1
WO2008001537A1 PCT/JP2007/058245 JP2007058245W WO2008001537A1 WO 2008001537 A1 WO2008001537 A1 WO 2008001537A1 JP 2007058245 W JP2007058245 W JP 2007058245W WO 2008001537 A1 WO2008001537 A1 WO 2008001537A1
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WO
WIPO (PCT)
Prior art keywords
active material
particles
negative electrode
secondary battery
material layer
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/JP2007/058245
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English (en)
Japanese (ja)
Inventor
Tomoyoshi Matsushima
Shinji Ishii
Yoshiki Sakaguchi
Kiyotaka Yasuda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsui Kinzoku Co Ltd
Original Assignee
Mitsui Mining and Smelting Co Ltd
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Filing date
Publication date
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Publication of WO2008001537A1 publication Critical patent/WO2008001537A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/137—Electrodes based on electro-active polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1399—Processes of manufacture of electrodes based on electro-active polymers
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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
    • 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 a negative electrode for a polymer electrolyte secondary battery such as a lithium polymer secondary battery.
  • the present applicant has previously described an active material comprising a pair of current collecting surface layers whose surfaces are in contact with an electrolytic solution, and particles of an active material having a high ability to form a lithium compound, interposed between the surface layers.
  • a negative electrode for a non-aqueous electrolyte secondary battery provided with a layer has been proposed (see Patent Document 1).
  • the active material layer of the negative electrode is infiltrated with a metal material having a low lithium compound forming ability, and active material particles are present in the infiltrated metal material. Since the active material layer has such a structure, the negative electrode is less likely to fall off even if it becomes fine due to expansion and contraction of the particles due to charge / discharge. As a result, the use of this negative electrode has the advantage of increasing the battery's lifetime.
  • Patent Document 1 US2006— 0115735A1
  • an object of the present invention is to provide a negative electrode for a polymer electrolyte secondary battery having further improved performance as compared with the above-described conventional negative electrode.
  • the present invention includes an active material layer containing particles of an active material, and at least a part of the surface of the particles has a low ability to form a potassium compound, is coated with a metal material !, and Voids are formed between the particles coated with a metal material, and mercury intrusion method CFIS R 1655)
  • the negative electrode for a polymer electrolyte secondary battery is characterized in that the porosity of the active material layer measured in accordance with the above is 15 to 45%.
  • FIG. 1 is a schematic view showing a cross-sectional structure of an embodiment of a negative electrode for a polymer electrolyte secondary battery of the present invention.
  • FIG. 2 is a schematic view showing an enlarged main part of a cross section of the active material layer in the negative electrode shown in FIG.
  • FIG. 3 (a) to FIG. 3 (d) are process diagrams showing a method for manufacturing the negative electrode shown in FIG. Detailed Description of the Invention
  • FIG. 1 shows a schematic diagram of a cross-sectional structure of an embodiment of a negative electrode for a polymer electrolyte secondary battery of the present invention.
  • the negative electrode 10 of the present embodiment includes a current collector 11 and an active material layer 12 formed on at least one surface thereof.
  • the active material layer 12 is formed only on one side of the current collector 11 to show the state! /, But the active material layer is formed on both sides of the current collector. Have you been?
  • the active material layer 12 includes particles 12a of the active material.
  • the active material a material capable of occluding and releasing lithium ions is used. Examples of such materials include silicon-based materials, tin-based materials, aluminum-based materials, and germanium-based materials.
  • the tin-based material for example, an alloy containing tin, cobalt, carbon, and at least one of nickel and chromium is preferably used.
  • a silicon-based material is particularly preferable.
  • the silicon-based material a material capable of occluding lithium and containing silicon, for example, silicon alone, an alloy of silicon and metal, silicon oxide, or the like can be used. These materials can be used alone or in combination.
  • the metal include one or more elements selected from the group consisting of Cu, Ni, Co, Cr, Fe, Ti, Pt, W, Mo, and Au. Of these metals, Cu, Ni, and Co are preferred, and Cu and Ni are preferably used because of their excellent electronic conductivity and low ability to form lithium compounds.
  • a particularly preferable silicon-based material is silicon or silicon oxide having a high lithium storage capacity.
  • the active material layer 12 at least a part of the surface of the particle 12a is covered with a metal material having a low ability to form a lithium compound.
  • the metal material 13 is a material different from the constituent material of the particles 12a. Voids are formed between the particles 12a coated with the metal material. That is, the metal material covers the surface of the particle 12a in a state in which a gap is provided so that the polymer gel electrolyte can reach the particle 12a.
  • the metal material 13 is conveniently represented as a thick line surrounding the periphery of the particle 12a.
  • “Low ability to form lithium compound” means that lithium does not form an intermetallic compound or solid solution, or even if lithium is formed, the amount of lithium is very small or very unstable.
  • the metal material 13 has conductivity, and examples thereof include copper, nickel, iron, cobalt, and alloys of these metals.
  • the metal material 13 is preferably a highly ductile material in which even if the active material particles 12a expand and contract, the surface coating of the particles 12a is not easily broken. It is preferable to use copper as such a material.
  • the metal material 13 is preferably present on the surface of the active material particles 12a over the entire thickness direction of the active material layer 12.
  • the active material particles 12 a are preferably present in the matrix of the metal material 13. As a result, even if the particles 12a expand and contract due to charge and discharge, even if they become fine powder, they are less likely to fall off.
  • the electrically isolated active material particles 12 a are generated, particularly in the deep part of the active material layer 12. The formation of the active material particles 12a is effectively prevented. This is particularly advantageous when a semiconductor is used as the active material and electron conductivity is poor, and a material such as a silicon-based material is used.
  • Metal material 13 is active material particles 12a throughout the thickness direction of active material layer 12 It can be confirmed by electron microscope mapping with the material 13 as a measurement target.
  • the metal material 13 covers the surfaces of the particles 12a continuously or discontinuously.
  • the metal material 13 continuously covers the surfaces of the particles 12a, it is preferable to form fine voids in the coating of the metal material 13 that allow the polymer gel electrolyte to flow.
  • the polymer gel electrolyte is supplied to the particle 12a through the portion of the surface of the particle 12a that is covered with the metal material 13. .
  • the metal material 13 may be deposited on the surface of the particle 12a by, for example, electrolytic plating according to the conditions described later.
  • the average thickness of the metal material 13 covering the surfaces of the active material particles 12a is preferably 0.05 to 2 / ⁇ ⁇ , more preferably 0.1 to 0.25 / zm. / !, thin! /. That is, the metal material 13 covers the surface of the active material particles 12a with a minimum thickness. This prevents the dropout due to the particles 12a from expanding and contracting due to charge and discharge to be pulverized while increasing the energy density.
  • the “average thickness” is a value calculated based on a portion of the surface of the active material particle 12 a that is actually covered with the metal material 13. Accordingly, the portion of the surface of the active material particles 12a not covered with the metal material 13 is not used as the basis for calculating the average value.
  • the void formed between the particles 12a coated with the metal material 13 serves as a flow path of the polymer gel electrolyte.
  • the polymer gel electrolyte smoothly circulates in the thickness direction of the active material layer 12 due to the presence of the voids, so that the cycle characteristics can be improved.
  • the voids formed between the particles 12a also serve as a space for relieving stress caused by the volume change of the active material particles 12a due to charge and discharge.
  • the increase in the volume of the active material particles 12a whose volume has been increased by charging is absorbed by the voids. As a result, it is difficult for the fine particles of the particles 12a to be generated, and significant deformation of the negative electrode 10 is effectively prevented.
  • the presence of the polymer gel electrolyte in the voids also has the advantage of acting as a cushion material that relieves the stress generated by the expansion and contraction of the polymer gel electrolyte force particles 12a.
  • the active material When the present inventors examined the voids formed in the active material layer 12, the active material When the porosity of the layer 12 is set to 15 to 45%, preferably 20 to 40%, more preferably 25 to 35%, the distribution of the polymer gel electrolyte in the active material layer 12 becomes extremely good, and the active material It was found to be extremely effective for stress relaxation accompanying the expansion and contraction of particles 12a. Furthermore, it has been found that the liquid retention of the polymer gel electrolyte in the voids is good. In particular, setting the upper limit to 35% is extremely effective in improving the conductivity and maintaining the strength in the active material layer, and setting the lower limit to 25% can broaden the choice of electrolyte.
  • the porosity in this range is higher than the porosity in the conventional negative electrode active material layer, for example, the porosity in the negative electrode described in Patent Document 1 described above.
  • the negative electrode 10 having such a high porosity active material layer it is possible to use a polymer gel electrolyte which is a material having low fluidity.
  • the void amount of the active material layer 12 is measured by a mercury intrusion method (JIS R 1655).
  • the mercury intrusion method is a technique for obtaining information on the physical shape of a solid by measuring the size and volume of pores in the solid.
  • the principle of the mercury intrusion method is to apply pressure to mercury to inject it into the pores of the measurement object and measure the relationship between the pressure applied at that time and the volume of mercury that has been pushed in (intruded). In this case, mercury enters the active material layer 12 in the order of the large void force.
  • the void amount measured at a pressure of 90 MPa is regarded as the entire void amount.
  • the porosity (%) of the active material layer 12 is obtained by dividing the void amount per unit area measured by the above method by the apparent volume of the active material layer 12 per unit area. Calculated by multiplying by 100.
  • the active material layer 12 is preferably an electrolytic plating using a predetermined plating bath on a coating film obtained by applying a slurry containing particles 12a and a binder onto a current collector and drying the slurry. And the metal material 13 is deposited between the particles 1 and 2a. The degree of precipitation of the metal material 13 affects the porosity value of the active material layer 12. In order to achieve a desired porosity, it is necessary that a space in which the plating solution can permeate is formed in the coating film. As a result of the examination by the present inventors, it was found that the particle size distribution of the active material particles 12a is a major factor in forming a space in which the plating solution can penetrate into the coating film as necessary and sufficient. did.
  • the particle size distribution represented by D / ⁇ as active material particles 12a is preferably 0. 05-0.5, more preferably 0.1 to 0.3, a desired degree of space is formed in the coating film, and sufficient penetration of the plating solution may occur. found. It has also been found that the coating film can be effectively prevented from peeling off when it is electrolyzed. D ZD force Si
  • the particles 12a having a sharp particle size distribution By using the particles 12a having a sharp particle size distribution, the voids between the particles can be increased when the particles 12a are packed at a high density. Conversely, when particles having a broad particle size distribution are used, small particles are likely to enter between large particles, and it is not easy to increase the voids between the particles.
  • the use of the particles 12a having a sharp particle size distribution has an advantage that the reaction varies.
  • the particle size of the active material particles 12a is also important, taking into account that the particle size distribution of the active material particles 12a is within the above-mentioned range.
  • the particle size of the active material particles 12a is excessively large, the particles 12a are easily expanded and contracted, so that fine particles are easily formed. As a result, the generation of electrically isolated particles 12g frequently occurs. If the particle size of the active material particles 12a is too small, the gaps between the particles 12a may be too small, and the gaps may be filled by penetration penetration described later. This has a negative effect on the improvement of the cycle characteristics. Therefore, in the present embodiment, the active material particles 12a have an average particle diameter of 0.1 to 5 111, particularly 0.2 to 3 / ⁇ ⁇ .
  • the particle size distribution D / ⁇ and the average particle size D of the active material particles 12a are determined by laser diffraction scattering.
  • the porosity of the active material layer 12 it is preferable to sufficiently infiltrate the plating solution into the coating film.
  • the conditions for depositing the metal material 13 appropriate by electrolytic plating using the plating solution.
  • the plating conditions include the composition of the mating bath, the pH of the plating bath, and the current density of electrolysis.
  • the pH of the plating bath it is preferable to adjust it to more than 7 and 11 or less, particularly 7.1 or more and 11 or less.
  • the metal material 13 covering the active material particles 12a tends to be thick, and it may be difficult to form desired voids between the particles 12a.
  • the current efficiency is deteriorated and gas generation is likely to occur, which may reduce the production stability.
  • a copper pyrophosphate bath having a P ratio of 6.5 to 10.5 is used, the size of the voids formed between the active material particles 12a and the number of polymer gels in the active material layer 12 This is very advantageous for electrolyte distribution.
  • the bath composition, electrolysis conditions, and pH are preferably as follows.
  • the calculated void ratio of the active material layer 12 measured by the mercury intrusion method is within the above range, in lOMPa It is preferable that the calculated void ratio of the active material layer 12 measured by the mercury injection method is 10 to 40%. Further, it is preferable that the porosity calculated from the void amount of the active material layer 12 measured by the mercury intrusion method in IMPa is 0.5 to 15%. Furthermore, it is preferable that the porosity calculated from the porosity force of the active material layer 12 measured by the mercury intrusion method at 5 MPa is 1 to 35%. As described above, the mercury intrusion conditions are gradually increased in the mercury intrusion measurement.
  • the porosity measured at pressure IMPa is mainly derived from large voids.
  • the porosity measured at pressure lOMPa V reflects the presence of small voids.
  • the active material layer 12 is preferably prepared by subjecting a coating film obtained by applying and drying a slurry containing particles 12a and a binder to electrolysis using a predetermined plating bath. It is formed by depositing and depositing the metal material 13 between the particles 12a. Therefore, as shown in FIG. 2, the above-mentioned large void S1 is mainly derived from the space between the particles 12a, while the small void S2 described above is mainly a metal material that precipitates on the surface of the particle 12a. It is thought that it originates in the space between the crystal grains 14 of. Large void S1 is the main As a space to relieve stress caused by the expansion and contraction of the particles 12a. On the other hand, the small void S2 mainly serves as a route for supplying the polymer gel electrolyte to the particles 12a. By balancing the abundance of these large voids S1 and small voids S2, the cycle characteristics are further improved.
  • the thickness of the active material layer 12 is preferably 10 to 40 / ⁇ ⁇ , more preferably 15 to 30 ⁇ m, and still more preferably 18 to 25 ⁇ m.
  • a thin surface layer (not shown) may be formed on the surface of the active material layer 12. Further, the negative electrode 10 may not have such a surface layer.
  • the thickness of the surface layer is as thin as 0.25 ⁇ m or less, preferably 0.1 ⁇ m or less. There is no limit to the lower limit of the thickness of the surface layer.
  • the negative electrode 10 When the negative electrode 10 is thin or has a surface layer or has the surface layer, a secondary battery is assembled using the negative electrode 10, and the battery is initially charged. The overvoltage can be reduced. This means that lithium can be prevented from being reduced on the surface of the negative electrode 10 when the secondary battery is charged. The reduction of lithium leads to the generation of dendrites that cause short circuits between the two electrodes.
  • the surface layer covers the surface of the active material layer 12 continuously or discontinuously.
  • the surface layer has a large number of fine voids (not shown) that are open to the surface and communicate with the active material layer 12. Have, prefer to have. It is preferable that the fine voids exist in the surface layer so as to extend in the thickness direction of the surface layer. The fine voids allow the polymer gel electrolyte to circulate. The role of the fine voids is to supply the polymer gel electrolyte into the active material layer 12.
  • the fine voids are the proportion of the area covered with the metal material 13, that is, the coverage is 95% or less, particularly 80% or less.
  • the size is preferably 60% or less.
  • the surface layer is composed of a metal compound having a low lithium compound forming ability.
  • This metal material may be the same as or different from the metal material 13 present in the active material layer 12.
  • the surface layer may have a structure of two or more layers having two or more different metal material forces. Considering the ease of production of the negative electrode 10, the metal material 13 present in the active material layer 12 and the metal material constituting the surface layer are preferably the same type.
  • the negative electrode 10 of the present embodiment has high resistance to bending because the porosity in the active material layer 12 is a high value.
  • the MIT folding resistance measured according to JIS C 6471 is preferably 30 times or more, more preferably 50 times or more.
  • the high folding resistance is extremely advantageous since the negative electrode 10 is folded when the negative electrode 10 is folded or wound and accommodated in the battery container.
  • the MIT folding device for example, Toyo Seiki Seisakusho's film folding fatigue tester (Part No. 54 9) is used, with a bending radius of 0.8 mm, a load of 0.5 kgf, and a sample size of 15 X 150 mm. can do.
  • the current collector 11 in the negative electrode 10 may be the same as that conventionally used as the current collector of the negative electrode for a polymer electrolyte secondary battery. It is preferable that the current collector 11 has a low ability to form a lithium compound as described above and has a metal material strength. Examples of such metal materials are as described above. In particular, it is preferably made of copper, nickel, stainless steel or the like. Also, it is possible to use a copper alloy foil represented by Corson alloy foil. Further, as the current collector, a metal foil having a normal tensile strength (JIS C 2318) of preferably 500 MPa or more, for example, a copper film layer formed on at least one surface of the aforementioned Corson alloy foil can be used.
  • JIS C 2318 normal tensile strength
  • a current collector having a normal elongation CFIS C 2318) of 4% or more is also preferable to use. This is because when the tensile strength is low, stress is generated due to the stress when the active material expands, and when the elongation is low, the current collector may crack.
  • the thickness of the current collector 11 is preferably 9 to 35 / ⁇ ⁇ in consideration of the balance between maintaining the strength of the negative electrode 10 and improving the energy density.
  • chromate treatment, triazole compound and imidazole compound are used. It is preferable to carry out an antifungal treatment using an organic compound such as
  • a coating film is formed on the current collector 11 using a slurry containing active material particles and a binder, and then the coating is electrolyzed.
  • a current collector 11 is prepared as shown in FIG. Then, a slurry containing active material particles 12 a is applied onto the current collector 11 to form a coating film 15.
  • the surface roughness of the coating film forming surface of the current collector 11 is preferably 0.5 to 4 / ⁇ ⁇ at the maximum height of the contour curve. When the maximum height exceeds 4 m, the accuracy of forming the coating film 15 is reduced, and current concentration tends to occur at the protrusions. When the maximum height is less than 0, the adhesion of the active material layer 12 tends to decrease.
  • the active material particles 12a those having the above-described particle size distribution and average particle size are preferably used.
  • the slurry contains a binder and a diluting solvent.
  • the slurry may also contain a small amount of conductive carbon material particles such as acetylene black and graphite.
  • the conductive carbon material is contained in an amount of 1 to 3% by weight with respect to the weight of the active material particles 12a.
  • the content of the conductive carbon material is less than 1% by weight, the viscosity of the slurry is lowered and the sedimentation of the active material particles 12a is promoted, so that it is difficult to form a good coating film 15 and a uniform void. Become.
  • the content of the conductive carbon material exceeds 3% by weight, plating nuclei concentrate on the surface of the conductive carbon material, and a good coating is formed.
  • binder styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polyethylene (PE), ethylene propylene monomer (EPDM), or the like is used.
  • SBR styrene butadiene rubber
  • PVDF polyvinylidene fluoride
  • PE polyethylene
  • EPDM ethylene propylene monomer
  • diluting solvent N-methylpyrrolidone, cyclohexane or the like is used.
  • the amount of the active material particles 12a in the slurry is preferably about 30 to 70% by weight.
  • the amount of the binder is preferably about 0.4 to 4% by weight.
  • a dilute solvent is added to these to form a slurry.
  • the formed coating film 15 has a large number of minute spaces between the particles 12a.
  • the current collector 11 on which the coating film 15 is formed is immersed in a plating bath containing a metal material having a low ability to form a lithium compound. By immersion in the plating bath, the plating solution penetrates into the minute space in the coating film 15. And reaches the interface between the coating film 15 and the current collector 11. Under this condition, electrolytic plating is performed to deposit metal species on the surface of the particles 12a (hereinafter, this plating is also referred to as penetration plating). The penetration is performed by using the current collector 11 as a force sword, immersing the counter electrode as the anode in the plating bath, and connecting both electrodes to the power source.
  • the deposition of the metal material by the penetration adhesion proceeds by applying one side force of the coating film 15 to the other side. Specifically, as shown in FIGS. 3B to 3D, the interfacial force between the coating film 15 and the current collector 11 is also electrolyzed so that the deposition of the metal material 13 proceeds toward the coating film surface. Make a mess.
  • the surface of the active material particles 12a can be successfully coated with the metal material 13, and a void is successfully formed between the particles 12a coated with the metal material 13. can do.
  • the porosity of the voids can be easily set within the preferred range described above.
  • the conditions for the penetration for depositing the metal material 13 include the composition of the plating bath, the pH of the plating bath, and the current density of electrolysis. Such conditions are as described above.
  • the deposition of the metal material 13 proceeds from the interface between the coating film 15 and the current collector 11 toward the surface of the coating film.
  • fine particles 13a that have a substantially constant thickness and also have a nucleating force of the metal material 13 are present in layers.
  • the adjacent fine particles 13a are combined to form larger particles, and when the deposition proceeds further, the particles are combined to continuously cover the surface of the active material particles 12a. It becomes like this.
  • the penetration staking is terminated when the metal material 13 is deposited in the entire thickness direction of the coating film 15.
  • a surface layer (not shown) can be formed on the upper surface of the active material layer 12. In this way, the target negative electrode is obtained as shown in FIG. 3 (d).
  • the negative electrode 10 is preferably subjected to an antifouling treatment.
  • an organic antifungal using a triazole compound such as benzotriazole, carboxybenzotriazole, tolyltriazole and imidazole, or an inorganic protective using cobalt, nickel, chromate or the like can be employed.
  • the negative electrode 10 thus obtained is suitably used as a negative electrode for a polymer electrolyte secondary battery such as a lithium ion polymer secondary battery.
  • the positive electrode of the battery is prepared by suspending a positive electrode active material and, if necessary, a conductive agent and a binder in a suitable solvent to prepare a positive electrode mixture, applying this to a current collector, drying, roll rolling, It can be obtained by pressing, cutting and punching.
  • the active material layer of the positive electrode is previously impregnated with a polymer gel electrolyte to be combined.
  • the positive electrode active material conventionally known positive electrode active materials such as lithium-containing metal composite oxides such as lithium nickel composite oxide, lithium mangan composite oxide, lithium cobalt composite oxide and the like are used.
  • LiCoO LiCoO
  • a lithium transition metal composite oxide containing at least both Zr and Mg and a lithium transition metal composite oxide having a layered structure and containing at least both Mn and Ni be able to.
  • the use of a positive electrode active material can be expected to increase the end-of-charge voltage without deteriorating charge / discharge cycle characteristics and thermal stability.
  • the average primary particle diameter of the positive electrode active material is 5 ⁇ m or more and 10 ⁇ m or less, and the weight average molecular weight of the binder used for the positive electrode is preferably 3 in view of the balance between packing density and reaction area.
  • the polyvinylideneidene is from 50,000 to 2,000,000. This is because it can be expected to improve the discharge characteristics in a low temperature environment.
  • the polymer gel electrolyte includes a matrix polymer, an organic solvent, and a lithium salt.
  • a matrix polymer polyethylene oxide, polypropylene oxide, polytetrafluoroethylene, polyvinylidene fluoride, polyfluoride bur, polyacrylic acid, polymethacrylic acid, polyacrylonitrile, polycarbonate, polyethylene glycol and the like can be used.
  • Lithium salts include LiCIO, LiAlCl, LiPF, LiAsF, LiSb
  • Examples thereof include F, LiBF, LiSCN, LiCl, LiBr, Lil, LiCFSO, and LiCFSO.
  • organic solvent examples include ethylene carbonate, jetyl carbonate, dimethyl carbonate, propylene carbonate, butylene carbonate, y-butyrolatone, and the like.
  • a current collector having an electrolytic copper foil strength of 18 / zm in thickness was acid-washed at room temperature for 30 seconds. After the treatment, it was washed with pure water for 15 seconds.
  • a slurry containing Si particles was applied on the current collector to a thickness of 15 m to form a coating film.
  • the average particle size D of Si particles is 2
  • D ZD is a microtrack particle size distribution measuring instrument (No. 9320-X10) manufactured by Nikkiso Co., Ltd.
  • the current collector on which the coating film was formed was immersed in a copper pyrophosphate bath having the following bath composition, and by electrolysis, copper penetrated into the coating film to form an active material layer. did.
  • the electrolysis conditions were as follows. DSE was used for the anode. A DC power source was used as the power source.
  • the penetration staking was terminated when copper was deposited over the entire thickness direction of the coating film, and washed with water and subjected to an anti-bacterial treatment with benzotriazole (BTA) to obtain a target negative electrode.
  • BTA benzotriazole
  • Si particles with the average particle size D and particle size distribution D / ⁇ shown in Table 1 are used.
  • a negative electrode was obtained in the same manner as in Example 1 except that.
  • Si particles with the average particle size D and particle size distribution D / ⁇ shown in Table 1 are used.
  • Example 2 In place of the copper pyrophosphate bath used in Example 1, a copper sulfate bath having the following composition was used. The current density was 5AZdm 2 and the bath temperature was 40 ° C. DSE electrode is used for anode It was. A DC power source was used as the power source. A negative electrode was obtained in the same manner as Example 1 except for these.
  • Si particles with the average particle size D and particle size distribution D / ⁇ shown in Table 1 are used.
  • a negative electrode was obtained in the same manner as in Example 1 except that.
  • the negative electrodes obtained in the examples and comparative examples were measured with a mercury porosimeter. The results are shown in Table 1. Separately, lithium ion polymer secondary batteries were manufactured using the negative electrodes obtained in Examples and Comparative Examples. LiCo Ni Mn O is used as the positive electrode
  • the positive electrode active material layer was impregnated with the following polymer gel electrolyte.
  • the capacity retention rate up to 100 cycles was measured for the secondary battery.
  • the capacity retention rate was calculated by measuring the discharge capacity at each cycle, dividing the value by the initial discharge capacity, and multiplying by 100.
  • the charging conditions were 0.5C and 4.2V, and constant current * constant voltage (CCCV).
  • the discharge conditions were 0.5C and 2.7V, and constant current (CC).
  • the first cycle was set to 0.05C
  • the 2nd to 4th cycles were set to 0.1C
  • the 5th to 7th cycles were set to 0.5C
  • the 8th to 10th cycles were set to 1C. The results are shown in Table 1.
  • a low-fluidity even a polymer gel electrolyte can be circulated through the active material layer with a necessary and sufficient path so that the polymer gel electrolyte can easily reach the active material layer. Therefore, the entire region in the thickness direction of the active material layer is used for the electrode reaction. As a result, cycle characteristics are improved. In addition, even if fine particles are generated due to the expansion and contraction of the particles due to charge and discharge, the particles do not easily fall off.

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Abstract

L'invention concerne une électrode négative (10) utilisée dans un accumulateur à électrolyte polymère qui comprend une couche de matériau actif (12) contenant une particule (12a) d'un matériau actif. Au moins une partie de la surface de la particule (12a) est recouverte d'un matériau métallique (13) dont la capacité à former un composé de lithium est faible. Un vide est constitué entre les particules (12a) qui sont recouvertes du matériau métallique (13). Le taux de porosité de la couche de matériau actif est compris entre 15 et 45%. Le matériau métallique (13) est de préférence présent sur la totalité de l'aire d'une partie de la surface de la particule qui s'étend dans la direction de l'épaisseur de la couche de matériau actif. La particule (12a) du matériau actif est, également de préférence, composée d'un matériau silicone, et la couche de matériau actif (12) contient un matériau carboné conducteur dans une proportion comprise entre 1 et 3% en poids par rapport à la quantité pondérale de la particule (12a) du matériau actif.
PCT/JP2007/058245 2006-06-30 2007-04-16 Électrode négative pour accumulateur à électrolyte polymère Ceased WO2008001537A1 (fr)

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CN102054969A (zh) * 2009-11-04 2011-05-11 三星Sdi株式会社 可再充电锂电池用的负极及其制造方法和可再充电锂电池

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JP4998358B2 (ja) 2008-04-08 2012-08-15 ソニー株式会社 リチウムイオン二次電池用負極およびリチウムイオン二次電池
WO2010151572A1 (fr) 2009-06-23 2010-12-29 A123 Systems, Inc. Électrodes pour piles et procédés de fabrication associés
JP5515785B2 (ja) * 2010-01-27 2014-06-11 ソニー株式会社 リチウムイオン二次電池およびリチウムイオン二次電池用負極
JP5510084B2 (ja) 2010-06-03 2014-06-04 ソニー株式会社 リチウムイオン二次電池用負極、リチウムイオン二次電池、電動工具、電気自動車および電力貯蔵システム
KR102240050B1 (ko) * 2016-08-30 2021-04-16 와커 헤미 아게 리튬 이온 전지의 애노드

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JPH11242954A (ja) * 1997-01-28 1999-09-07 Canon Inc 電極構造体、二次電池及びそれらの製造方法
JP2004241329A (ja) * 2003-02-07 2004-08-26 Mitsui Mining & Smelting Co Ltd 非水電解液二次電池用負極
JP2004296412A (ja) * 2003-02-07 2004-10-21 Mitsui Mining & Smelting Co Ltd 非水電解液二次電池用負極活物質の製造方法
JP2005285581A (ja) * 2004-03-30 2005-10-13 Sanyo Electric Co Ltd リチウム二次電池用負極及びリチウム二次電池

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11242954A (ja) * 1997-01-28 1999-09-07 Canon Inc 電極構造体、二次電池及びそれらの製造方法
JP2004241329A (ja) * 2003-02-07 2004-08-26 Mitsui Mining & Smelting Co Ltd 非水電解液二次電池用負極
JP2004296412A (ja) * 2003-02-07 2004-10-21 Mitsui Mining & Smelting Co Ltd 非水電解液二次電池用負極活物質の製造方法
JP2005285581A (ja) * 2004-03-30 2005-10-13 Sanyo Electric Co Ltd リチウム二次電池用負極及びリチウム二次電池

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102054969A (zh) * 2009-11-04 2011-05-11 三星Sdi株式会社 可再充电锂电池用的负极及其制造方法和可再充电锂电池

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