WO2008018214A1 - Électrode négative pour un accumulateur à électrolyte non aqueux - Google Patents

Électrode négative pour un accumulateur à électrolyte non aqueux Download PDF

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Publication number
WO2008018214A1
WO2008018214A1 PCT/JP2007/058417 JP2007058417W WO2008018214A1 WO 2008018214 A1 WO2008018214 A1 WO 2008018214A1 JP 2007058417 W JP2007058417 W JP 2007058417W WO 2008018214 A1 WO2008018214 A1 WO 2008018214A1
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Prior art keywords
particles
active material
negative electrode
metal material
metal
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PCT/JP2007/058417
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English (en)
Japanese (ja)
Inventor
Hideaki Matsushima
Masahiro Hyakutake
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Mitsui Mining & Smelting Co., Ltd.
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Publication of WO2008018214A1 publication Critical patent/WO2008018214A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
    • H01M4/36—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
    • H01M4/626—Metals
    • 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
    • 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
    • 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 non-aqueous electrolyte secondary battery such as a lithium secondary battery.
  • Patent Document 1 as a negative electrode for a lithium secondary battery, a paste obtained by adding and kneading graphite, polyvinyl alcohol, carboxymethyl cellulose and water to silicon powder as an active material is collected. What was apply
  • coated on the collector is proposed.
  • silicon has a large degree of volume change due to lithium absorption and release, when charge and discharge are repeated, it is likely to be pulverized due to the stress caused by expansion and contraction and to be detached from the current collector. As a result, the vital characteristics deteriorate.
  • an active material layer including a pair of front and back surfaces in contact with the electrolyte and having conductivity and including particles of the active material between the surfaces.
  • a negative electrode for a non-aqueous electrolyte secondary battery was proposed (see Patent Document 2).
  • a metal material having a low ability to form a lithium compound is infiltrated, and particles of the active material are present in the infiltrated metal material. Since the active material layer has such a structure, in this negative electrode, even if it is pulverized due to expansion and contraction of the particles due to charge and discharge, it is difficult for the particles to come off. As a result, using this negative electrode has the advantage of prolonging the cycle life of the battery.
  • the negative electrode previously proposed by the present applicant can prevent the particles of the active material from falling off due to repeated charging and discharging, but the metal material described above It has been found that depending on the degree of penetration of the electrolyte, sufficient gaps may not be formed between the particles of the active material, and the electrolyte may not flow smoothly.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 11 214010
  • Patent Document 2 US 2006-0121345 A1
  • an object of the present invention is to provide a negative electrode for a non-aqueous electrolyte secondary battery, the performance of which is further improved than that of the above-described prior art negative electrode. Disclosure of the invention
  • the present invention comprises an active material layer containing particles of the active material, and a metal material deposited by electroless plating is present between the particles, and the non-aqueous electrolyte solution 2 is characterized. It provides a negative electrode for a secondary battery.
  • FIG. 1 is a schematic view showing a cross-sectional structure of an embodiment of a negative electrode for a non-aqueous electrolyte secondary battery of the present invention.
  • FIGS. 2 (a) and 2 (b) are scanning electron micrograph images of longitudinal sections of the active material layer in the negative electrode obtained in Examples 1 and 2.
  • FIG. 3 is a scanning electron microscopic image of a longitudinal section of the active material layer of the negative electrode obtained in Example 3.
  • FIG. 1 is a schematic view of the cross-sectional structure of an embodiment of the negative electrode for a non-aqueous 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 on both sides of the current collector. It may be
  • the active material layer 12 contains particles 12 a of the active material.
  • a material capable of absorbing and releasing lithium ions is used. Examples of such materials include silicon-based materials, tin-based materials, aluminum-based materials and germanium-based materials. In order to improve the capacity density per weight of negative electrode, particularly silicon-based materials and tin-based materials are preferable, and particularly silicon-based materials are preferable.
  • Silicon-based material and tin-based material active material particles 12a include materials capable of storing lithium and containing silicon or tin, for example, particles of silicon alone or particles of tin alone, silicon, or silicon Examples thereof include compound particles of tin and metal, and c) particles obtained by coating a surface of a single silicon particle or a single tin particle with a metal. Another example is silicon oxide. Each of these materials may be used alone or in combination. it can.
  • the silicon-based particles or tin-based particles are compound particles of silicon or tin and metal in the above-mentioned mouth
  • the compound includes silicon or an alloy of tin and metal, and 1) silicon or silicon or Solid solution of tin and metal 2) Intermetallic compound of silicon or tin and metal 3) Silicon single phase or single phase tin, metal single phase, silicon or solid solution of tin and metal, silicon or tin It is any one of a complex composed of two or more phases of an intermetallic compound with a metal.
  • the metal Cu, Ag, Ni, Co, and Ce are preferable, and Cu, Ag, and Ni are preferably used from the viewpoint of excellent electron conductivity and low ability to form a lithium compound.
  • the composition of silicon or tin and metal in the compound particle of the mouth is preferably such that the amount of silicon or tin is 30 to 99.9% by weight and the amount of metal is 0.1 to 70% by weight.
  • a further preferred composition is selected in an appropriate range depending on the method of producing compound particles.
  • the compound particle force is a binary alloy of silicon or tin and metal, and when the alloy is produced using a rapid cooling method, the amount of silicon or tin is preferably 40 to 90% by weight. I'm sorry.
  • the amount of metal is preferably 10 to 60% by weight.
  • the compound particles are silicon or a ternary or higher alloy of tin and metal, in addition to the binary alloys described above, B, Al, Sn, Fe, Cr, Zn, In, V, Y
  • the group force consisting of Zr, Nb, Ta, W, La, Pr, Pd and Nd may also contain a small amount of selected elements. This has the additional effect of suppressing fines. In order to further enhance this effect, these elements are preferably contained in the compound particle in an amount of 0.01 to 50% by weight, in particular 0.5 to 50% by weight.
  • an alloy containing tin, cobalt, carbon, and at least one of nickel and chromium is preferably used as a tin-based alloy particle.
  • lithium may be absorbed into the active material particles made of the silicon-based material or the tin-based material.
  • the alloy particle may be produced, for example, by a quenching method, so that the crystallite size of the alloy becomes fine. At the same time, it is also preferable to suppress the pulverization and maintain the electron conductivity by being uniformly dispersed.
  • a quenching method first, a molten metal of a raw material containing silicon or tin and a metal is prepared. The raw material is made into molten metal by high frequency melting. Silicon in molten metal or The ratio of tin to metal is in the range described above.
  • the temperature of the molten metal be 1200 to 1500 ° C., particularly 130 to 1450 ° C. in relation to the quenching condition.
  • the vertical type method is used V, and an alloy is obtained from the molten metal. That is, the molten metal is poured into a copper or iron crucible to obtain a quenched silicon-based alloy or tin-based alloy ingot. The ingot is crushed and sieved, and for example, those having a particle diameter of 40 m or less are provided to the present invention.
  • the silicon-based particles or tin-based particles are particles obtained by coating the surface of silicon single particles or tin single particles of the above c) with metal (these particles are combined with metal-coated particles), the coating is As the metal, the same metal as that contained in the particles of the above-mentioned mouth), for example, copper etc. is used.
  • the amount of silicon or tin in the metal-coated particles 70 to 99. 9 wt 0/0, especially 80 to 99 wt%, it forces S preferably especially 85 to 95.
  • the amount of coated metal including copper is preferably 0.1 to 30% by weight, particularly 1 to 20% by weight, especially 5 to 15% by weight.
  • the metal-coated particles are produced, for example, using an electroless plating method.
  • a plating bath is prepared in which silicon particles or tin particles are suspended and which contains a coating metal such as copper.
  • silicon particles or tin particles are electrolessly plated to coat the surface of the silicon particles or tin particles with the coated metal.
  • concentration of silicon particles or tin particles in the plating bath is preferably about 400 to 600 gZl.
  • the concentration of copper sulfate is 6 to 9 gZl
  • the concentration of Rochelle salt is 70 to 90 g Zl, which is preferable from the viewpoint of control of the force plating rate.
  • the pH of the plating bath is preferably 12 to 13, and the bath temperature is preferably 20 to 30 ° C.
  • formaldehyde or the like is used as a reducing agent contained in the plating bath, and the concentration thereof can be about 15 to 30 cc Zl.
  • a commercial item can also be used as an electroless plating bath.
  • particles 12 a of the various active materials described above particularly preferable are point forces of high storage capacity of lithium and particles of silicon alone or silicon oxide.
  • the metal material 13 is present between the particles 12 a.
  • the metal material 13 is a material different from the material of the particles 12a, and is preferably a metal material having a low ability to form a lithium compound. This metal material 13 is deposited by electroless plating. is there.
  • the metal material 13 covers at least a part of the surface of the particle 12a.
  • An air gap is formed between the particles 12a coated with the metal material 13. That is, the metal material 13 is deposited between the particles 12 a in a state in which a non-aqueous electrolyte solution containing lithium ions can reach the particles 12 a.
  • the metal material 13 is conveniently represented as a thick line surrounding the periphery of the particle 12a.
  • lithium compound means that it does not form an intermetallic compound or a solid solution with lithium, or if it forms lithium, it is a force or very unstable that is a trace amount of lithium.
  • the metal material 13 has conductivity, and examples thereof include copper, nickel, iron, cobalt, an alloy of these metals, and the like, which are materials having a low ability to form a lithium compound. Silver can also be used as a metal other than these.
  • the metal material 13 is preferably a highly ductile material in which the coating on the surface of the particles 12a is not easily broken even if the particles 12a of the active material expand and contract. It is preferred to use copper as such material U ,.
  • the metal material 13 deposited by electroless plating is preferably present on the surface of the particles 12 a of the active material over the entire thickness of the active material layer 12.
  • particles 12a of the active material are present in the matrix of the metallic material 13.
  • the electron conductivity of the entire active material layer 12 is ensured through the metal material 13, the electrically isolated active material particles 12 a are formed, and in particular, the active isolation electrically isolated in the deep part of the active material layer 12. The generation of particles 12a of the substance is effectively prevented.
  • the metal material 13 coating the surface of the particles 12 a of the active material preferably has an average thickness of 0.5 to 2 / ⁇ , more preferably 0.1 to 0.25 / zm. And, it's too thin! That is, the metal material 13 covers the surface of the particles 12 a of the active material with a minimum thickness. As a result, while the energy density is increased, the particles 12 a are prevented from coming off due to expansion and contraction and pulverization due to charge and discharge.
  • the “average thickness” is a value calculated based on the portion of the surface of the particles 12 a of the active material that is actually covered by the metal material 13. Therefore, the part of the surface of the particles 12a of the active material which is not coated with the metal material 13 can not be used as a basis for calculating the average value.
  • the voids formed between the particles 12a coated with the metal material 13 deposited by electroless plating serve as a flow path of the non-aqueous electrolyte containing lithium ions. Since the non-aqueous electrolyte flows smoothly in the thickness direction of the active material layer 12 due to the presence of the voids, cycle characteristics can be improved. Furthermore, the space formed between the particles 12a also serves as a space for relieving stress caused by volume change of the particles 12a of the active material during charge and discharge. An increase in the volume of the particles of the active material 12a whose volume has been increased by charging is absorbed by the void. As a result, pulverization of the particles 12 a is less likely to occur, and significant deformation of the negative electrode 10 is effectively prevented.
  • active material layer 12 preferably applies a predetermined plating bath to a coating film obtained by applying and drying a slurry containing particles 12 a and a binder on a current collector. It is formed by performing the electroless plating used and depositing the metal material 13 between the particles 12a.
  • the ratio of voids formed in the active material layer is preferably about 15 to 45% by volume, and particularly preferably about 20 to 40% by volume.
  • the void volume of the active material layer 12 is measured by mercury intrusion method CFIS R 1655).
  • the mercury pressure method is a method for obtaining information on the physical shape of a solid by measuring the size and volume of pores in the solid. The principle of mercury porosimetry is that the pressure on mercury Pressure into the pores of the object to be measured, and the pressure applied at that time,
  • the void percentage (%) of the active material layer 12 is obtained by dividing the void volume per unit area measured by the above-mentioned method by the apparent volume of the active material layer 12 per unit area and multiplying it by 100. It asks by.
  • the porosity can be controlled by appropriately selecting the particle size of the particles 12 a of the active material.
  • the particles 12a preferably have a maximum particle size of 30 m or less, more preferably 10 m or less.
  • D value when the particle size of the particles is expressed by D value,
  • the particle size of the particles is measured by laser diffraction / scattering particle size distribution measurement, electron microscopic observation (SEM observation).
  • the thickness of the active material layer is 10 to 40 111, preferably 15 to 30 m, and more preferably 18 to 25 m.
  • a thin surface layer (not shown) may be formed on the surface of the active material layer 12.
  • 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 has a thickness as described above, has a surface layer, or has a surface layer, thereby assembling a secondary battery using the negative electrode 10 and performing initial charging of the battery
  • the over-voltage can be reduced. This means that reduction of lithium on the surface of the negative electrode 10 can be prevented during charging of the secondary battery.
  • the reduction of lithium leads to the generation of dendrite which causes a short circuit between the two poles.
  • the percentage of the area covered with the metal material 13, that is, the coverage is 95% or less, particularly 80% or less, and particularly 60% or less It is preferable that it is such a magnitude
  • the surface layer has a low ability to form a lithium compound, and is constituted of metal material force.
  • This metal material may be the same as or different from the metal material 13 deposited in the active material layer 12.
  • the surface layer may have a structure of two or more layers composed of two or more different metal materials. In consideration of the ease of manufacture 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 resistance of the negative electrode 10 to bending becomes high.
  • the MIT folding resistance measured according to JIS C 6471 preferably has a high folding resistance of 30 times or more, more preferably 50 times or more.
  • the high folding resistance is extremely advantageous because the negative electrode 10 is broken when the negative electrode 10 is folded or wound and housed in the battery case.
  • a film-with-film folding fatigue tester product number 549) manufactured by Toyo Seiki Seisaku-sho, Ltd. is used, and a bending radius is 0.8 mm, a load is 0.5 kgf, It can be measured with a size of 15 x 150 mm.
  • the current collector 11 of the negative electrode 10 the same one as conventionally used as a current collector of a negative electrode for a non-aqueous electrolyte secondary battery can be used.
  • the current collector 11 is preferably composed of a metal material having a low ability to form a lithium compound as described above. Examples of such metal materials are as described above. In particular, it is preferably made of copper, nickel, stainless steel or the like. In addition, copper alloy foils represented by Corson alloy foils can also be used. Furthermore, as the current collector, a metal foil having a normal tensile strength (JIS C 2318) of preferably 500 MPa or more, for example, one obtained by forming a copper coating layer on at least one surface of the aforementioned Corson alloy foil can be used.
  • JIS C 2318 normal tensile strength
  • a coating film is formed on the current collector 11 using a slurry containing particles of an active material and a binder, and then the coating film is subjected to electroless plating.
  • a slurry containing particles 12 a of the active material is applied onto the current collector 11 to form a coating film.
  • 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 formation accuracy of the coating film 15 is reduced. If the maximum height is less than 0.5 m, the adhesion of the active material layer 12 is likely to be reduced.
  • the slurry contains, in addition to the particles of the active material, a binder, a dilution solvent, etc.
  • the slurry may also contain a small amount of particles of conductive carbon material such as acetylene black or graphite.
  • conductive carbon material such as acetylene black or graphite.
  • the content of the conductive carbon material is less than 1% by weight, the viscosity of the slurry is As it is lowered to accelerate the sedimentation of the particles 12a of the active material, it becomes difficult to form a good coating film and uniform voids.
  • plating nuclei are concentrated on the surface of the conductive carbon material to form a good coating.
  • styrene butadiene rubber SBR
  • polybiphenyl difluoride PVDF
  • polyethylene PE
  • ethylene propylene diene monomer EPDM
  • a dilution solvent N-methyl pyrrolidone, cyclohexane or the like is used.
  • the amount of particles 12a of the active material 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. Add a dilution solvent to these to make a slurry.
  • the formed coating film has a large number of microspaces between particles 12a.
  • the current collector 11 on which the coating film is formed is immersed in an electroless plating bath. By immersion in the plating bath, the plating solution intrudes into the minute space in the coating film and reaches the interface between the coating film and the current collector 11. Under this condition, electroless plating is performed to deposit plated metal species on the surface of the particles 12a.
  • the deposition rate of the plated metal species is 0.50 to: L 5 mZ 20 minutes, in particular 0.2 to 0.5 ⁇ m.
  • the point force be such that crystal grains of an appropriate size are formed.
  • the electroless plating liquid various commercial products can be used according to the type of metal to be deposited, and the type is not critical in the present invention.
  • a plating solution it is preferable to use a plating solution having excellent uniformity of deposition, covering properties, and followability to irregularities from the viewpoint of depositing the metal uniformly and precisely on the surface of the particles 12a of the active material. Yes. From this point of view, it is preferable to use a plating solution that is used for electroless plating in through holes and via holes such as printed wiring boards (PWBs)!
  • PWBs printed wiring boards
  • the plating solution has a pH of more than 7 to 13, particularly preferably, in order to allow electroless plating to proceed properly by the substitution reaction accompanying the elution of Si. It is preferable to use those which are 1 to 12.5. This pH is the pH at the temperature at the time of plating.
  • the electroless plating is terminated when the metallic material 13 is deposited over the entire thickness of the coating film.
  • a surface layer (not shown) can be formed on the upper surface of the active material layer 12.
  • the target negative electrode shown in FIG. 1 is obtained.
  • the current collector having a coating film containing particles of the active material Prior to electroless plating, the current collector having a coating film containing particles of the active material is electrolytically plated It is possible to carry out electrolytic plating by immersing in a bath of the above to deposit a metallic material between the particles in the coating. In this way, plating nuclei are formed for electroless plating to be performed next, so that electroless plating can be performed more successfully. This is particularly effective when using particles 12a of an active material containing Si, which is a material with poor electron conductivity.
  • the degree of metal deposition in the electrolytic plating prior to electroless plating is sufficient if the amount is small enough to form plating nuclei.
  • the metal to be deposited by electrolytic plating and the metal to be deposited by electroless plating may be the same as or different from each other.
  • a copper pyrophosphate bath When copper is used as a metal to be deposited as a plating solution used for electrolytic plating prior to electroless plating, for example, a copper pyrophosphate bath can be used. When nickel is used as the metal to be deposited, for example, an alkaline nickel bath can be used. By using these plating solutions, it is possible to form uniform fine-grained nuclei on the surface of the particles 12a.
  • the bath composition, electrolytic conditions and pH are preferably as follows.
  • the bath composition, electrolytic conditions and pH are preferably as follows.
  • the particles 12 of the active material When using particles containing Si, which is a material with poor electron conductivity, as the particles 12 of the active material, the particles of the active material are substituted for the electrolytic plating prior to the electroless plating. Electroless plating may be performed using a metal-coated surface of By using such particles 12a, the same effect as in the case of performing electrolytic plating prior to electroless plating is exhibited.
  • the negative electrode 10 it is also preferable to protect the negative electrode 10 after electroless plating.
  • the protection treatment for example, organic protection using a triazole-based compound such as benzotriazole, carboxybenzotriazole, tolyltriazole or the like, imidazole, etc., inorganic protection using cobalt, nickel, chromium etc. It can be adopted.
  • the negative electrode 10 thus obtained is suitably used as a negative electrode for non-aqueous electrolyte secondary batteries such as, for example, lithium secondary batteries.
  • the positive electrode of the battery is prepared by suspending the positive electrode active material and, if necessary, the conductive agent and the binder in an appropriate solvent, preparing a positive electrode mixture, applying it to a current collector, drying it, and rolling it. It is obtained by pressing, further cutting and punching.
  • the positive electrode active material conventionally known positive electrode active materials including lithium transition metal composite oxides such as lithium nickel composite oxide, lithium manganese composite oxide, lithium cobalt composite oxide and the like are used. Also, as a positive electrode active material, LiCoO
  • a lithium transition metal complex oxide containing at least both Zr and Mg in 2 and a mixture of a lithium transition metal complex oxide having a layered structure and containing at least both Mn and Ni It can be used preferably.
  • a strong positive electrode active material it can be expected to increase the charge termination voltage which is accompanied by a decrease in charge / discharge cycle characteristics and thermal stability.
  • the average primary particle diameter of the positive electrode active material is 5 ⁇ m to 10 ⁇ m, and the weight-average molecular weight of the binder used for the positive electrode is 350, which is preferable in view of the balance between the packing density and the reaction area.
  • it is a poly (vinylidene fluoride) having a molecular weight of 1,000 or more and 2,000 or less. This is because it can be expected to improve the discharge characteristics in a low temperature environment.
  • a synthetic resin non-woven fabric, a polyolefin such as polyethylene or polypropylene, or a porous film of polytetrafluoroethylene is preferably used.
  • the polyolefin fine It is preferable to use a separator in which a thin film of a benzene derivative is formed on one side or both sides of the porous membrane.
  • the separator preferably has a piercing strength of not less than 0.2 NZ wm and not more than 0.49 N / ⁇ m and a tensile strength of not less than 40 MPa and not more than 150 MPa in the winding axis direction. This is because the damage to the separator can be suppressed and the occurrence of the internal short circuit can be suppressed even when using the negative electrode active material that largely expands and contracts with charge and discharge.
  • the non-aqueous electrolytic solution is a solution of a lithium salt as a supporting electrolyte dissolved in an organic solvent.
  • Examples thereof include CI, LiPF, LiAsF, LiSbF, LiCl, LiBr, Lil, LiC 3 F 2 SO 4 and the like.
  • CF SO Li, (CF 2 SO 4) NLi, and (C 4 F 2 SO 4) NLi are preferred because of their excellent resistance to water degradation.
  • organic solvent examples include ethylene carbonate, jetyl carbonate, dimethyl carbonate, propylene carbonate, butylene carbonate and the like.
  • vinylene carbonate and 0.1 to 1% by weight of divinylsulfone, 0.1 to 1.5% by weight of 1,4 butanediol dimethane with respect to the whole non-aqueous electrolyte It is preferable to incorporate a sulfonate from the viewpoint of further improving charge-discharge cycle characteristics.
  • non-aqueous electrolyte 4 fluoro-1, 3 dioxolane 1, 2- ion, 4 black mouth
  • a high dielectric constant solvent having a dielectric constant of 30 or more such as cyclic carbonate derivatives having a halogen atom such as 1,3 dioxolan-2-one or 4 trifluoromethyl mono, 1-3 dioxolane 2-one Is also preferred. It is because reduction resistance is high and decomposition is difficult.
  • the content of fluorine ions in the electrolytic solution is in the range of 14 mass ppm or more and 1290 mass ppm or less.
  • the electrolytic solution contains an appropriate amount of fluorine ions, a film such as lithium fluoride derived from the fluorine ions is formed on the negative electrode, and the electrolytic solution on the negative electrode is formed.
  • at least one additive in the acid anhydride and derivative thereof be contained in 0.010 mass% to 10 mass%. As a result, a film is formed on the surface of the negative electrode, which is also a force capable of suppressing the decomposition reaction of the electrolytic solution.
  • succinic anhydride, dartalic anhydride, maleic anhydride, phthalic anhydride, Phthalic anhydride derivatives such as 2-sulfobenzoic acid anhydride, citraconic acid anhydride, itaconic acid anhydride, diglycolic acid anhydride, hexafluoroglutaric acid anhydride, 3-fluorophthalic acid anhydride, 4-fluorophthalic acid anhydride, or Anhydrous 3, 6-Epoxide 1, 2, 3, 6-Tetrahydrophthalic Acid, Anhydrous 1, 8 Naphthalic Acid, Anhydrous 2, 3 Naphthalene Carboxylic Acid, Anhydrous 1, 2-Cyclopentanedicarboxylic Acid, 1, 2- Cyclo 1,2 cycloalkanedicarboxylic acid anhydrides such as hexanedicarboxylic acid, or t
  • the current collector which is also an electrolytic copper foil having a thickness of 18 m, was acid washed at room temperature for 30 seconds. After treatment, it was washed with pure water for 15 seconds. A slurry containing Si particles was applied onto the current collector to a film thickness of 15 m to form a coating film.
  • the average particle diameter D is the Microtrac particle size distribution measuring device manufactured by Nikkiso Co., Ltd.
  • Measurement was carried out using a measuring instrument (No. 9320-X100).
  • the current collector on which the coating film was formed was immersed in Melplate Cu-390, an electroless copper plating solution manufactured by Meltex Co., Ltd. Electroless plating at 25 ° C for 60 minutes to form an active material layer did. Electroless plating was terminated when copper was deposited over the entire thickness of the coating, washed with water, and treated with benzotriazole (BTA) to obtain a target negative electrode.
  • BTA benzotriazole
  • Example 1 the current collector on which a coating was formed was immersed in a copper pyrophosphate bath having the following bath composition, and electrolytic plating was performed.
  • the conditions of electrolysis were as follows.
  • As the anode D SE was used.
  • the power supply used DC power supply.
  • the electrolysis time was 1.5 minutes.
  • electroless plating of copper was performed in the same manner as in Example 1 to obtain a negative electrode.
  • the scanning electron micrograph of the longitudinal cross section of the active material layer in the obtained negative electrode is shown in FIG. 2 (b).
  • the silicon particles are electrolessly plated, and the surfaces of the silicon particles are coated with copper to form copper-coated silicon particles. Obtained.
  • the concentration of silicon particles in the plating bath was 500 gZl, the concentration of copper sulfate was 7.5 g Zl, and the concentration of Rochelle salt was 85 g Zl.
  • the plating bath had a pH of 12.5 and a bath temperature of 25 ° C. Formaldehyde was used as a reducing agent, and its concentration was 22 cc Zl.
  • the D value of the obtained copper-coated silicon particles was 2.5 / z m.
  • the composition of the particles is S
  • a negative electrode was obtained in the same manner as in Example 1 except that the copper-coated silicon particles were used.
  • the scanning electron micrograph of the longitudinal cross section of the active material layer in the obtained negative electrode is shown in FIG.
  • Silicon 80% Pour a 1400 ° C melt containing 20% nickel into a copper bowl, A quenched silicon-nickel alloy ingot was obtained. The ingot was crushed by a jet mill and sieved to obtain active material particles. The obtained active material particles were placed in 20% KOH and etched for 20 minutes. The D value of the active material particles thus obtained is 2.5.
  • a negative electrode was obtained in the same manner as Example 1, except that this active material particle was used.
  • a negative electrode was obtained in the same manner as in Example 1 except that electroless plating was not performed.
  • Example 1 the current collector on which the coating film was formed was immersed in a copper sulfate bath having the following bath composition with reference to Patent Document 2, and electrolytic plating was performed.
  • the conditions for electrolysis were as follows.
  • the electrolytic plating was terminated when copper was deposited over the entire thickness of the coating. Other than that was carried out similarly to Example 1, and obtained the negative electrode.
  • the negative electrode obtained in Examples and Comparative Examples was subjected to a tape peeling test according to JIS C 5012 to evaluate the adhesion between the current collector and the active material layer.
  • the ratio (%) of ⁇ was calculated, with X being exfoliated at the interface between the current collector and the active material layer and ⁇ with no exfoliation.
  • Adhesion is over 90% and porosity is over 15%.
  • Adhesion is more than 50% and less than 90%, and porosity is more than 15%.
  • Adhesion is 50% or less or porosity is 15% or less.
  • Example 1 Electroless plating 88 38 ⁇ Example 2 Electro plating ⁇ Electroless plating 92 35 ⁇ Example 3 Electroless plating particles 87 36 ⁇
  • Comparative example 1 No plating 8 50 X Comparative example 2 Electroplated (copper sulfate) 100 3 X
  • the metal material is deposited on the surface of the particles of the active material by electroless plating, sufficient electron conductivity is imparted to the particles.
  • the metal material is deposited between particles by electroless plating, the adhesion between the particles and the particles and the current collector is improved.
  • the metal material can be uniformly deposited in the thickness direction of the active material layer. The cycle characteristics are improved by these reasons.

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Abstract

Selon l'invention, l'électrode négative (10) utilisée dans un accumulateur à électrolyte non aqueux comprend une couche de matériau actif (12) contenant une particule (12a) d'un matériau actif. Un matériau métallique est déposé entre les particules (12a) par plaquage anélectrolytique. 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 matériau métallique (13) est présent sur la totalité de l'aire d'une partie de la surface de la particule telle qu'elle s'étend dans la direction de l'épaisseur de la couche de matériau actif. La surface de la particule (12a) est de préférence recouverte du matériau métallique par placage électrolytique, et un matériau métallique identique ou différent du matériau métallique (13) est déposé sur le matériau métallique (13) par placage anélectrolytique.
PCT/JP2007/058417 2006-08-10 2007-04-18 Électrode négative pour un accumulateur à électrolyte non aqueux WO2008018214A1 (fr)

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JP2006219050 2006-08-10
JP2006-219050 2006-08-10
JP2007042791A JP2008066272A (ja) 2006-08-10 2007-02-22 非水電解液二次電池用負極
JP2007-042791 2007-02-22

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JP2013522820A (ja) * 2010-03-11 2013-06-13 エルジー ケム． エルティーディ． 有機高分子−ケイ素複合体粒子及びその製造方法とそれを含む負極及びリチウム二次電池

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US20110200869A1 (en) * 2009-08-28 2011-08-18 Mami Matsumoto Lithium secondary battery and method for fabricating the same

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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

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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

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Publication number Priority date Publication date Assignee Title
JP2013522820A (ja) * 2010-03-11 2013-06-13 エルジー ケム． エルティーディ． 有機高分子−ケイ素複合体粒子及びその製造方法とそれを含む負極及びリチウム二次電池
US9142859B2 (en) 2010-03-11 2015-09-22 Lg Chem, Ltd. Polymer-silicon composite particles, method of making the same, and anode and lithium secondary battery including the same

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