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WO2009084330A1 - Matériau actif d'électrode positive pour batterie rechargeable à électrolyte non aqueux et batterie rechargeable à électrolyte non aqueux comprenant le matériau actif d'électrode positive - Google Patents

Matériau actif d'électrode positive pour batterie rechargeable à électrolyte non aqueux et batterie rechargeable à électrolyte non aqueux comprenant le matériau actif d'électrode positive Download PDF

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WO2009084330A1
WO2009084330A1 PCT/JP2008/070434 JP2008070434W WO2009084330A1 WO 2009084330 A1 WO2009084330 A1 WO 2009084330A1 JP 2008070434 W JP2008070434 W JP 2008070434W WO 2009084330 A1 WO2009084330 A1 WO 2009084330A1
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active material
negative electrode
electrode active
positive electrode
lithium
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Japanese (ja)
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Tomoya Takeuchi
Koichi Numata
Hiroei Sasaki
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Mitsui Kinzoku Co Ltd
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Mitsui Mining and Smelting Co Ltd
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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Complex oxides containing nickel and at least one other metal element
    • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
    • C01G53/44—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese
    • C01G53/50—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C01P2002/52—Solid solutions containing elements as dopants
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • 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 positive electrode active material for a non-aqueous electrolyte secondary battery such as a lithium secondary battery.
  • the present invention also relates to a non-aqueous electrolyte secondary battery having the positive electrode active material.
  • Graphite is generally used as the negative electrode active material for lithium ion secondary batteries.
  • their power consumption has increased remarkably, and the need for large-capacity secondary batteries is increasing. It is difficult to meet. Therefore, negative electrode active materials made of Sn-based materials and Si-based materials, which are materials having a higher capacity than graphite, have been actively developed.
  • a negative electrode active material made of Sn-based material or Si-based material generally has a large irreversible capacity at the first charge. Therefore, in order to utilize the high capacity characteristics of these negative electrode active materials, it is necessary to use these negative electrode active materials in combination with a positive electrode active material having a high capacity and an appropriate irreversible capacity.
  • Non-Patent Document 1 As a high-capacity positive electrode active material, a solid solution system material of Li 2 MnO 3 —LiMO 2 (M is Ni, Co, etc.) has recently attracted attention (see Non-Patent Document 1).
  • M is Ni, Co, etc.
  • Non-Patent Document 1 a solid solution system material of Li 2 MnO 3 —LiMO 2 (M is Ni, Co, etc.) has recently attracted attention.
  • M is Ni, Co, etc.
  • the negative electrode material used in combination with this positive electrode material is metallic lithium, the above-described problem of irreversible capacity during the initial charge does not occur. Therefore, it is not clear from the description of the literature what effect is achieved when the positive electrode material described in the literature is used in combination with a negative electrode material made of an Sn-based material or an Si-based material.
  • An object of the present invention is to provide a non-aqueous electrolyte secondary battery that can fully utilize the high-capacity characteristics of a negative electrode active material made of Sn-based material or Si-based material.
  • the present invention comprises a lithium transition metal composite oxide represented by the following formula (1), and is used in combination with a negative electrode active material containing Si or Sn. An active material is provided.
  • the present invention also includes a positive electrode having the positive electrode active material and a negative electrode having a negative electrode active material containing Si or Sn, and the active material layer of the negative electrode contains particles of an active material containing Si or Sn. And a non-aqueous electrolyte solution in which at least a part of the surface of the particle is coated with a metal material having a low lithium compound forming ability and a void is formed between the particles coated with the metal material.
  • a secondary battery is provided.
  • FIG. 3 It is a schematic diagram which shows the cross-sectional structure of one Embodiment of the negative electrode used for the nonaqueous electrolyte secondary battery of this invention. It is process drawing which shows the manufacturing method of the negative electrode shown in FIG. 3 is an X-ray diffraction result of the lithium transition metal composite oxide powder obtained in Example 1.
  • FIG. 3 It is a schematic diagram which shows the cross-sectional structure of one Embodiment of the negative electrode used for the nonaqueous electrolyte secondary battery of this invention. It is process drawing which shows the manufacturing method of the negative electrode shown in FIG. 3 is an X-ray diffraction result of the lithium transition metal composite oxide powder obtained in Example 1.
  • FIG. 3 It is a schematic diagram which shows the cross-sectional structure of one Embodiment of the negative electrode used for the nonaqueous electrolyte secondary battery of this invention. It is process drawing which shows the manufacturing method of the negative electrode shown in FIG. 3 is an X-ray diffraction result of the lithium transition metal composite oxide
  • the nonaqueous electrolyte secondary battery of the present invention (hereinafter also simply referred to as a secondary battery or a battery) has a positive electrode, a negative electrode, and a separator disposed between them as its basic constituent members.
  • the space between the positive electrode and the negative electrode is filled with a non-aqueous electrolyte via a separator.
  • the battery of the present invention may be in the form of a cylindrical shape, a square shape, a coin shape or the like provided with these basic components. However, it is not limited to these forms.
  • the positive electrode used in the battery of the present invention has, for example, a positive electrode active material layer formed on at least one surface of a current collector.
  • the positive electrode active material layer contains an active material.
  • the active material used in the present invention is a specific lithium transition metal composite oxide.
  • This compound is represented by the following formula (1).
  • the compound represented by the formula (1) is composed of a single solid solution or composite of two types of lithium transition metal composite oxides.
  • the composition of each element of the lithium transition metal composite oxide represented by the formula (1) can be measured by ICP analysis.
  • the lithium transition metal composite oxide represented by the above formula (1) is a single solid solution of two types of lithium transition metal composite oxide
  • the solid solution is represented by the following formula (2) It is preferable that Li 1 + x (Mn ⁇ Co ⁇ Ni ⁇ ) 1-x O 2 .aLi 4/3 Mn 2/3 O 2 (2) (Wherein a, ⁇ , ⁇ , ⁇ and x are as defined above.) Whether or not the compound represented by the formula (2) is composed of a single solid solution can be determined from the X-ray diffraction measurement of this compound.
  • the lithium transition metal composite oxide represented by the formula (1) is combined with Si or Sn, which is a negative electrode active material having a capacity higher than that of graphite, to constitute a battery.
  • the inventors have found that the charge / discharge capacity is increased and the irreversible capacity at the first charge is increased by increasing the cut-off voltage of the charge compared to the conventional lithium secondary battery. As a result, the battery can have a high capacity and a long life. Details are as follows.
  • a part of the crystal structure of the lithium transition metal composite oxide represented by the formula (1), which is the positive electrode active material, is changed and included by increasing the cut-off voltage of the precharge.
  • a part of lithium is supplied to the negative electrode active material.
  • a part of the supplied lithium is accumulated in the negative electrode as an irreversible capacity. Therefore, charging / discharging after the preliminary charging is started from a state in which lithium is occluded in the negative electrode active material, so that charging / discharging after the preliminary charging is performed approximately 100% reversibly.
  • the reason for this is that the site stably alloying with lithium in the negative electrode active material is preferentially used for occlusion of lithium in preliminary charging, so that lithium can be easily occluded and released during the second and subsequent charging.
  • Preliminary charging is charging performed for the first time after the battery is assembled, and is generally performed by a battery manufacturer before shipping the product to the market for the purpose of safety and operation check.
  • lithium secondary batteries sold in the market are usually precharged already. Therefore, the first charge / discharge after the preliminary charge and the subsequent discharge after the preliminary charge corresponds to the first charge / discharge.
  • charge / discharge after discharge after preliminary charge is referred to as “charge / discharge after first time”.
  • the degree of irreversible capacity is the theoretical capacity of the negative electrode active material, which is the amount of lithium supplied from the lithium transition metal composite oxide represented by the formula (1) that has accumulated in the negative electrode active material without returning to the positive electrode by discharge.
  • the amount is preferably 9 to 50%, more preferably 9 to 40%, and particularly preferably 10 to 30%.
  • the upper limit of the amount of lithium accumulated in the negative electrode active material is 30% of the theoretical capacity of the negative electrode active material, it is released from the positive electrode active material during precharging in addition to the above-mentioned advantages related to energy density
  • the balance between the amount of lithium to be transferred and the amount of lithium that reversibly moves between the positive and negative electrodes during charge and discharge after preliminary charging is improved. By taking this balance, the amount of lithium reversibly moved between the positive and negative electrodes during the first charge and discharge is sufficient. If a large amount of lithium is excessively applied to the negative electrode active material during preliminary charging, the amount of lithium that reversibly moves between the positive and negative electrodes during the first and subsequent charging / discharging tends to decrease.
  • the irreversible capacity in the present invention refers to a capacity obtained by subtracting the capacity corresponding to the amount of lithium returning from the negative electrode to the positive electrode at the time of discharging following the preliminary charging from the capacity corresponding to the amount of lithium moving from the positive electrode to the negative electrode during the preliminary charging. .
  • the amount of lithium supplied from the positive electrode to the negative electrode by precharging may be 50 to 90% of the theoretical capacity of the negative electrode active material, taking into account the amount that returns to the positive electrode by discharging. preferable.
  • the reason for this is that the sites for alloying with lithium in the negative electrode active material are likely to be formed throughout the active material by precharging, and the entire negative electrode active material, and thus the negative electrode active material layer, in the first and subsequent charging. This is because the entire region can be easily occluded with lithium.
  • the theoretical capacity of the negative electrode in the present invention is a discharge capacity obtained when a bipolar battery having lithium as a counter electrode is produced, and the bipolar battery is charged to 0.01V and then discharged to 1.5V. .
  • the above-described charging adopts the constant current mode and the rate of 0.05 C, and when the cell voltage reaches 0.01 V. It is preferable to switch to the constant voltage mode and perform charging until the current value decreases to 1/5 of that in the constant current mode. From the same viewpoint, it is preferable to adopt a constant current mode and a rate of 0.05 C as the discharge conditions.
  • the substantial discharge capacity of the positive electrode is a value measured by the following method. That is, a coin battery is manufactured by the method described in the Example, using the positive electrode manufactured by the method described in Example 1 described later and the negative electrode using Si alone as an active material.
  • the charge / discharge conditions are as follows, and the obtained discharge capacity is defined as the substantial discharge capacity of the positive electrode.
  • the form of Si in the negative electrode of Si alone does not affect the measurement results.
  • the present inventors have confirmed that.
  • Preliminary charge After charging to 4.5 V with a constant current of 0.01 C (100 hour rate), the voltage is set to a constant potential from 4.5 V, and the process ends when the current value reaches 1/10 of the previous constant current value.
  • Discharge after precharge When 2.7V is reached at a constant current of 0.1 C (10 hour rate), the process ends.
  • Initial charge After charging to 4.2 V with a constant current of 0.1 C (10 hour rate), the voltage is changed from 4.2 V to a constant potential, and the process ends when the current value reaches 1/10 of the previous constant current value.
  • Initial discharge When 2.7 V is reached at a constant current of 0.1 C (10 hour rate), the discharge is completed. The reason for defining the initial discharge capacity as the substantial discharge capacity is to reflect the irreversible capacity lost in the preliminary charge and the subsequent discharge. Note that the preliminary charging is charging performed only after the battery is assembled.
  • Storing a part of lithium as an irreversible capacity in the negative electrode active material has the following advantages. That is, at each discharge after the precharge, lithium is always occluded in the negative electrode active material, so that its ionic conductivity and electronic conductivity are always good, and the negative electrode has a small polarization. Become. This makes it difficult for the voltage of the negative electrode to rapidly decrease at the end of discharge. This is particularly advantageous when a Si-based material, particularly a simple substance of Si, is used as the negative electrode active material.
  • the lithium transition metal composite oxide represented by the formula (1) is used only after assembling a secondary battery using Si alone as the negative electrode active material.
  • the ratio of the irreversible capacity accumulated in the negative electrode when the precharge, which is the charge to be performed, under the following conditions and the discharge capacity when the initial charge / discharge performed after the precharge is performed under the following conditions (the former / the latter) Is preferably from 0.15 to 0.55, particularly from 0.25 to 0.45, particularly from 0.35 to 0.45, from the viewpoint of increasing the capacity of the battery and improving the cycle characteristics.
  • Preliminary charging After charging to 4.5 V with a constant current of 0.01 C (100 hour rate), the voltage is set to a constant potential from 4.5 V, and the process ends when the current value reaches 1/10 of the previous constant current value.
  • Discharge after pre-charging It ends when it reaches 2.7V at a constant current of 0.1C (10 hour rate).
  • First charge After charging to 4.2 V with a constant current of 0.1 C (10 hour rate), the voltage is set to a constant potential from 4.2 V, and the process ends when the current value reaches 1/10 of the previous constant current value.
  • First discharge It ends when it reaches 2.7V at a constant current of 0.1C (10 hour rate).
  • the lithium transition metal composite oxide represented by the formula (1) uses Si alone as a negative electrode active material, assembles a secondary battery, and performs initial charge when precharge and initial charge / discharge are performed under the above conditions.
  • the capacity is preferably 150 mAh or more, particularly 160 mAh or more per weight (g) of the positive electrode active material, from the viewpoint of increasing the capacity of the battery.
  • the lithium transition represented by the formula (1) as described later It is only necessary to adjust the crystallite size appropriately by performing the synthesis conditions of the metal composite oxide, for example, by increasing the reactivity by reducing the particle size of the raw material, or by increasing the firing temperature and causing grain growth. . Furthermore, what is necessary is just to control appropriately the particle size and shape of lithium transition metal complex oxide represented by Formula (1).
  • the particle size (D 50 ) of the positive electrode active material is preferably 50 ⁇ m or less, and particularly preferably 30 ⁇ m or less. By reducing the particle size, the specific surface area increases and the rate characteristics tend to improve. However, on the other hand, the high-temperature storage characteristics and density tend to decrease, and it is necessary to control the particle size to an optimum value according to the use of the battery.
  • the lithium transition metal composite oxide represented by the formula (1) which is a positive electrode active material, breaks down in the crystal structure even when the cut-off voltage of charge is increased as compared with a conventional positive electrode active material such as LiCoO 2. It is a material that is difficult to be used (this is also called “high withstand voltage”).
  • LiCoO 2 which is a general positive electrode active material
  • the crystal structure collapses due to release of oxygen or the like from the crystal when lithium of a certain amount or more is released.
  • the detailed mechanism of the cause of the high withstand voltage of the lithium transition metal composite oxide represented by the formula (1) is currently being elucidated. However, the structural stabilization due to rearrangement of cations in the crystal has occurred.
  • the secondary battery of the present invention can increase the cut-off voltage of charging compared to the conventional battery, and the charge and discharge after the first time are performed reversibly almost 100%.
  • the ability to increase the charge cut-off voltage is extremely advantageous in that the battery can have a high capacity.
  • it is not prevented that an inevitable impurity is contained in the lithium transition metal complex oxide represented by Formula (1).
  • the precharge cutoff / off potential is preferably set to 4.4 V or higher with respect to Li / Li + , particularly 4.4 to 5.0 V, particularly 4.5 to 5.0 V. It is preferable to do.
  • the pre-charge cut-off potential is set to less than 4.4 V, the effect of accumulating lithium as an irreversible capacity in the negative electrode active material becomes insufficient.
  • the cut-off voltage is preferably set higher than the cut-off voltage for charging after the preliminary charging. In other words, it is preferable that the cut-off voltage in the first and subsequent charging is set lower than the cut-off voltage in the preliminary charging.
  • the cut-off voltage is too low, charging and discharging are performed under the same conditions as those of a lithium secondary battery using a conventional positive electrode active material, and the lithium transition metal composite oxidation represented by the formula (1) is performed. You will not be able to make full use of the benefits of using things.
  • the cut-off voltage is too high, the non-aqueous electrolyte tends to decompose.
  • the cut-off potential in the first and subsequent charging is preferably 4.3 to 5.0 V, particularly 4.35 to 4.55 V, based on Li / Li + .
  • the working voltage range of the lithium secondary battery used conventionally is 3-4.3V. Since application of a voltage higher than this destroys the crystal structure of the positive electrode active material, lithium secondary battery manufacturers strictly control the voltage by providing a protection circuit for the battery. Therefore, a person skilled in the art usually does not employ a high voltage for improving the cycle characteristics.
  • the theoretical capacity of the negative electrode is 1.1 to 3.0 times, particularly 2.0 to 3.0 times the capacity of the positive electrode at the first and subsequent charge cut-off voltages (hereinafter, this value is referred to as the positive / negative capacity ratio).
  • the amount of each positive and negative active material to be used is set so that the precharge is higher than the cut-off voltage of the first and subsequent charges, so that When precharging is performed such that 50 to 90% of the lithium is supplied from the positive electrode to the negative electrode, there is an advantage that the entire negative electrode is activated. This advantage is unique when a negative electrode containing Si or Sn is used as the negative electrode active material.
  • lithium supplied from the lithium transition metal composite oxide represented by the formula (1) as described above is accumulated in the negative electrode as an irreversible capacity, and thus the advantages as described above are generated. .
  • the positive / negative electrode capacity ratio to be 1.1 times or more, the generation of lithium dendrites is prevented, and the safety of the battery is ensured.
  • the positive / negative electrode capacity ratio to be 2.0 times or more, it is possible to ensure a sufficient capacity maintenance rate.
  • capacitance of a negative electrode can fully be utilized by making positive / negative electrode capacity ratio 3.0 times or less, and the energy density of a battery can be improved.
  • the charge / discharge after the initial charge is determined based on the theoretical capacity of the negative electrode at the charge cut-off voltage. It is preferably carried out within the range of 0 to 90%, preferably 10 to 80%. That is, charging / discharging is preferably performed within the range (for example, in the range of 20 to 60%) with 0% and 90% of the theoretical capacity of the negative electrode as upper and lower limits. In addition, by performing charging up to 90% of the capacity of the negative electrode, excessive expansion of the active material can be suppressed, and cycle characteristics can be improved. In the present invention, since the definition of the theoretical capacity of the negative electrode is as described above, the point of 0% in the charge / discharge range is the discharge end point in the measurement of the theoretical capacity of the negative electrode.
  • a constant current control method or a constant current constant voltage control method as in the case of a conventional lithium secondary battery.
  • a constant current / constant voltage control method may be adopted for the preliminary charging, and a constant current control method may be adopted for the first and subsequent charging.
  • the discharging condition of the secondary battery of the present invention does not critically affect the battery performance, and the same condition as that of the conventional lithium secondary battery can be adopted.
  • the cut-off voltage of discharge in the secondary battery is preferably 2.0 to 3.5 V, particularly 2.5 to 3.0 V.
  • a is 0.1 ⁇ a ⁇ 0.4.
  • x is preferably 0 ⁇ x ⁇ 0.15, particularly preferably 0.01 ⁇ x ⁇ 0.10.
  • ⁇ is preferably 0.01 ⁇ ⁇ 0.50, particularly preferably 0.15 ⁇ ⁇ 0.40.
  • ⁇ is preferably 0 ⁇ ⁇ 0.50, particularly preferably 0.01 ⁇ ⁇ 0.30.
  • ⁇ is preferably 0.30 ⁇ ⁇ ⁇ 0.80, particularly preferably 0.40 ⁇ ⁇ ⁇ 0.65. If a is too large, the actual discharge capacity decreases, and if it is too small, the precharge amount is insufficient.
  • x is negative, Li will escape from the structure during preliminary charging than when x is positive, which may lead to deterioration in cycle characteristics. Further, if x is excessive, not only the substantial discharge capacity is reduced, but also gelation of the paste due to the increase in pH occurs during coating.
  • a, x, ⁇ , ⁇ , and ⁇ each represent a molar ratio.
  • the atomic ratio of the oxygen amount is described as “2” for convenience, but may have some non-stoichiometry.
  • the lithium transition metal composite oxide represented by the formula (1) is suitably produced by, for example, the following method.
  • a lithium salt compound, a manganese salt compound, a nickel salt compound, and a cobalt salt compound are used as raw materials. These are mixed at a predetermined ratio, dispersed in water, and pulverized with a wet pulverizer or the like until the average particle size (D 50 ) is 2 ⁇ m or less. Thereafter, it is granulated and dried using a thermal spray dryer or the like, and is preferably fired at 700 to 1100 ° C., more preferably at 800 to 950 ° C. in the air or oxygen atmosphere, and classified as necessary. it can.
  • the method for producing the lithium transition metal composite oxide represented by the formula (1) is not limited to such a method.
  • a transition metal composite hydroxide can be produced by a coprecipitation method, mixed with a lithium salt compound, fired, and classified as necessary.
  • lithium salt compound examples include lithium hydroxide, lithium carbonate, lithium nitrate, and lithium oxide. Of these, lithium hydroxide, carbonate and nitrate are preferred.
  • the manganese salt compound is not particularly limited, and examples thereof include manganese carbonate, manganese nitrate, manganese dioxide, and manganese chloride.
  • the nickel salt compound is not particularly limited, and examples thereof include nickel carbonate, nickel nitrate, nickel chloride, nickel oxyhydroxide, nickel hydroxide, and nickel oxide.
  • the cobalt salt compound is not particularly limited, and examples thereof include basic cobalt carbonate, cobalt nitrate, cobalt chloride, cobalt oxyhydroxide, cobalt hydroxide, and cobalt oxide.
  • the lithium transition metal composite oxide represented by the formula (1) may be used as the active material, or the lithium transition metal represented by the formula (1).
  • other positive electrode active materials may be used in combination.
  • examples of other positive electrode active materials include lithium transition metal composite oxides other than the lithium transition metal composite oxide represented by the formula (1) (LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiCo 1/3 Ni 1 / 3 Mn 1/3 O 2 etc.).
  • the amount of the other positive electrode active material used in combination can be about 50% by weight or less based on the weight of the lithium transition metal composite oxide represented by the formula (1).
  • the lithium transition metal composite oxide represented by the formula (1) is suspended in a suitable solvent together with a conductive agent such as acetylene black and a binder such as polyvinylidene fluoride. It is obtained by preparing a positive electrode mixture, applying it to at least one surface of a current collector made of aluminum foil or the like, drying it, and then rolling and pressing.
  • a conductive agent such as acetylene black
  • a binder such as polyvinylidene fluoride
  • the negative electrode used in the secondary battery of the present invention has a negative electrode active material layer formed on at least one surface of a current collector.
  • the negative electrode active material layer contains an active material.
  • the active material used in the present invention is a material containing Si or Sn.
  • the negative electrode active material containing Si is capable of occluding and releasing lithium ions.
  • silicon alone, an alloy of silicon and metal, silicon oxide, silicon nitride, silicon boride and the like can be used. These materials can be used alone or in combination.
  • the metal used in the alloy include one or more elements selected from the group consisting of Cu, Ni, Co, Cr, Fe, Ti, Pt, W, Mo, and Au.
  • Cu, Ni, and Co are preferable, and Cu and Ni are preferably used from the viewpoint of excellent electronic conductivity and a low ability to form a lithium compound.
  • lithium may be occluded in the negative electrode active material containing Si before or after the negative electrode is incorporated in the battery.
  • a particularly preferable negative electrode active material containing Si is silicon alone or silicon oxide from the viewpoint of high lithium storage capacity.
  • the negative electrode active material containing Sn, tin alone an alloy of tin and metal, or the like can be used. These materials can be used alone or in combination.
  • the metal that forms an alloy with tin 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 preferable.
  • An example of the alloy is a Sn—Co—C alloy.
  • the negative electrode active material layer can be, for example, a continuous thin film layer made of the negative electrode active material.
  • the negative electrode active material layer made of a thin film is formed on at least one surface of the current collector by various thin film forming means such as chemical vapor deposition, physical vapor deposition, and sputtering.
  • the thin film may be etched to form a large number of voids extending in the thickness direction.
  • a dry etching method using a dry gas or plasma can be employed for the etching.
  • the negative electrode active material layer may be a coating layer containing particles of the negative electrode active material, a sintered body layer containing particles of the negative electrode active material, or the like. Moreover, it may be a layer having a structure shown in FIG.
  • the negative electrode active material layer includes particles of an active material containing Si or Sn, and particles of a conductive carbon material or a metal material, and these particles may be in a mixed state in the active material layer.
  • silicon single particles or silicon oxide particles can be mixed with conductive carbon material particles or metal material particles.
  • a synthetic resin nonwoven fabric a polyolefin such as polyethylene or polypropylene, a porous film of polytetrafluoroethylene, or the like is preferably used.
  • a separator in which a thin film of a ferrocene derivative is formed on one side or both sides of a polyolefin microporous membrane.
  • the separator preferably has a puncture strength of 0.2 N / ⁇ m thickness or more and 0.49 N / ⁇ m thickness or less, and a tensile strength in the winding axis direction of 40 MPa or more and 150 MPa or less. This is because even if a Si-based or Sn-based material, which is a negative electrode active material that expands and contracts greatly with charge and discharge, can be used to suppress damage to the separator and suppress the occurrence of internal short circuits.
  • the nonaqueous electrolytic solution is a solution in which a lithium salt as a supporting electrolyte is dissolved in an organic solvent.
  • the lithium salt CF 3 SO 3 Li, ( CF 3 SO 2) NLi, (C 2 F 5 SO 2) 2 NLi, LiClO 4, LiA1Cl 4, LiPF 6, LiAsF 6, LiSbF 6, LiCl, LiBr, LiI And LiC 4 F 9 SO 3 .
  • These can be used alone or in combination of two or more.
  • CF 3 SO 3 Li, (CF 3 SO 2 ) NLi, and (C 2 F 5 SO 2 ) 2 NLi are preferably used because of their excellent water decomposition resistance.
  • organic solvent examples include ethylene carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, butylene carbonate, and the like.
  • vinylene carbonate and 0.1 to 1% by weight of divinyl sulfone and 0.1 to 1.5% by weight of 1,4-butanediol dimethanesulfonate with respect to the whole non-aqueous electrolyte. It is preferable from the viewpoint of further improving the charge / discharge cycle characteristics.
  • 1,4-butanediol dimethanesulfonate and divinylsulfone are decomposed stepwise to form a film on the positive electrode, so that the film containing sulfur becomes denser. It is thought that it is to become.
  • non-aqueous electrolytes 4-fluoro-1,3-dioxolan-2-one, 4-chloro-1,3-dioxolan-2-one or 4-trifluoromethyl-1,3-dioxolan-2-one
  • a high dielectric constant solvent having a relative dielectric constant of 30 or more such as a cyclic carbonate derivative having a halogen atom. This is because it has high resistance to reduction and is not easily decomposed.
  • an electrolytic solution in which the high dielectric constant solvent is mixed with a low viscosity solvent having a viscosity of 1 mPa ⁇ s or less such as dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate is also preferable. This is because higher ionic conductivity can be obtained. Furthermore, it is also preferable that the content of fluorine ions in the electrolytic solution is in the range of 14 mass ppm to 1290 mass ppm.
  • a coating film such as lithium fluoride derived from fluorine ions is formed on the negative electrode, and it is considered that the decomposition reaction of the electrolytic solution in the negative electrode can be suppressed.
  • at least one additive selected from the group consisting of acid anhydrides and derivatives thereof is contained in an amount of 0.001 to 10% by weight. This is because a film is formed on the surface of the negative electrode, and the decomposition reaction of the electrolytic solution can be suppressed.
  • This additive is preferably a cyclic compound containing a —C ( ⁇ O) —O—C ( ⁇ O) — group in the ring.
  • succinic anhydride glutaric anhydride, maleic anhydride, phthalic anhydride, 2-sulfobenzoic anhydride, citraconic anhydride, itaconic anhydride, diglycolic anhydride, hexafluoroglutaric anhydride, 3-fluorophthalic anhydride, Phthalic anhydride derivatives such as 4-fluorophthalic anhydride, or 3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, 1,8-naphthalic anhydride, 2,3-naphthalenecarboxylic acid anhydride, 1,2-cycloalkanedicarboxylic anhydride such as 1,2-cyclopentanedicarboxylic anhydride, 1,2-cyclohexanedicarboxylic acid, or cis-1,2,3,6-tetrahydrophthalic anhydride or 3,4, Tetrahydrophthalic anhydride such as 5,6-tetrahydrophthalic anhydride
  • FIG. 1 shows a schematic diagram of a cross-sectional structure of a preferred embodiment of a negative electrode used in the present invention.
  • the capacity of the battery is increased.
  • the cycle characteristics are extremely good.
  • the favorable rate characteristic at low temperature means that, for example, the battery of the present invention is particularly effective when used as a vehicle-mounted battery such as an electric vehicle or a hybrid vehicle.
  • the negative electrode 10 of this embodiment includes a current collector 11 and an active material layer 12 formed on at least one surface thereof. 1 shows a state in which the active material layer 12 is formed only on one side of the current collector 11 for convenience, the active material layer may be formed on both sides of the current collector. .
  • the active material layer 12 at least a part of the surface of the active material particles 12a containing Si is covered with a metal material having a low lithium compound forming ability.
  • the metal material 13 is a material different from the constituent material of the particles 12a. Gaps 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 ensured so that the non-aqueous electrolyte containing lithium ions can reach the particle 12a.
  • the metal material 13 is conveniently represented as a thick line surrounding the periphery of the particle 12a. Each particle is in direct contact with other particles or through the metal material 13.
  • “Low lithium compound forming ability” means that lithium does not form an intermetallic compound or solid solution, or even if formed, lithium is in a very small amount 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 coating on the surface 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 12 a 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.
  • the electrically isolated active material particles 12 a are generated, and in particular, the electrically isolated active material is deep in the active material layer 12. Generation of the particles 12a of the substance is effectively prevented.
  • the presence of the metal material 13 on the surface of the active material particles 12a over the entire thickness direction of the active material layer 12 can be confirmed by electron microscope mapping using the material 13 as a measurement target.
  • the metal material 13 covers the surface of the particle 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 non-aqueous electrolyte to flow.
  • the metal material 13 discontinuously coats the surface of the particle 12a, the non-aqueous electrolyte is supplied to the particle 12a through a portion of the surface of the particle 12a that is not covered with the metal material 13.
  • the metal material 13 may be deposited on the surfaces of the particles 12a by, for example, electrolytic plating in accordance with conditions described later.
  • the average thickness of the metal material 13 covering the surface of the active material particles 12a is preferably 0.05 to 2 ⁇ m, more preferably 0.1 to 0.25 ⁇ m. That is, the metal material 13 covers the surface of the active material particles 12a with a minimum thickness. As a result, while the energy density is increased, the particles 12a are prevented from falling off due to expansion / contraction and pulverization due to charge / discharge.
  • 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 particle 12a that is 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 has a function as a flow path of the non-aqueous electrolyte containing lithium ions. Since the non-aqueous electrolyte smoothly flows in the thickness direction of the active material layer 12 due to the presence of the voids, cycle characteristics can be improved. Further, the voids formed between the particles 12a also have a function 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, pulverization of the particles 12a is difficult to occur, and significant deformation of the negative electrode 10 is effectively prevented.
  • the active material layer 12 is preferably electrolyzed 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. It forms by plating and depositing the metal material 13 between the particle
  • the plating conditions include the composition of the plating bath, the pH of the plating bath, and the current density of electrolysis.
  • the pH of the plating bath it is preferably adjusted to 7.1 to 11.
  • the metal material 13 for plating it is preferable to use a copper pyrophosphate bath.
  • nickel for example, an alkaline nickel bath is preferably used.
  • a copper pyrophosphate bath even if the active material layer 12 is thick, because the voids can be easily formed over the entire thickness direction of the layer. Further, since the metal material 13 is deposited on the surface of the active material particles 12a and the metal material 13 is less likely to be deposited between the particles 12a, the voids between the particles 12a are also successfully formed.
  • the bath composition, electrolysis conditions and pH are preferably as follows.
  • Copper pyrophosphate trihydrate 85 to 120 g / l -Potassium pyrophosphate: 300-600 g / l Potassium nitrate: 15 to 65 g / l ⁇ Bath temperature: 45-60 °C ⁇ Current density: 1-7A / dm 2 -PH: Ammonia water and polyphosphoric acid are added to adjust the pH to 7.1 to 9.5.
  • a copper pyrophosphate bath it is preferable to use one having a P ratio defined by a ratio of P 2 O 7 weight to Cu weight (P 2 O 7 / Cu) of 5 to 12. .
  • the P ratio is less than 5, 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.
  • a P ratio exceeding 12 current efficiency is deteriorated, and gas generation is likely to occur, so that production stability may be lowered.
  • a copper pyrophosphate bath having a P ratio of 6.5 to 10.5 the size and number of voids formed between the active material particles 12a may be reduced in the active material layer 12. This is very advantageous for the flow of the water electrolyte.
  • the bath composition, electrolysis conditions and pH are preferably as follows.
  • Nickel sulfate 100-250 g / l ⁇
  • Ammonium chloride 15-30 g / l ⁇
  • Boric acid 15-45 g / l ⁇
  • Bath temperature 45-60 °C ⁇
  • Current density: 1-7A / dm 2 PH 25% by weight
  • aqueous ammonia Adjust so that the pH is 8 to 11 within the range of 100 to 300 g / l.
  • the ratio of the voids in the entire active material layer formed by the various methods described above is preferably about 15 to 45% by volume, particularly about 20 to 40% by volume.
  • 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 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 the mercury intrusion method is to apply a pressure to mercury to inject it into the pores of the object to be measured, and to measure the relationship between the pressure applied at that time and the volume of mercury that has been pushed in (intruded).
  • mercury enters sequentially from the large voids present in the active material layer 12.
  • 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 and multiplying it by 100. .
  • the porosity calculated from the void amount of the active material layer 12 measured by the mercury intrusion method was within the above range, and was measured by the mercury intrusion method at 10 MPa.
  • the porosity calculated from the void amount of the active material layer 12 is preferably 10 to 40%.
  • the porosity calculated from the void amount of the active material layer 12 measured by the mercury intrusion method at 1 MPa is preferably 0.5 to 15%.
  • the porosity calculated from the void amount of the active material layer 12 measured by the mercury intrusion method at 5 MPa is 1 to 35%. As described above, in the mercury intrusion measurement, mercury intrusion conditions are gradually increased.
  • the porosity measured at a pressure of 1 MPa is mainly derived from large voids.
  • the porosity measured at a pressure of 10 MPa reflects the presence of small voids.
  • the large voids described above are mainly derived from the spaces between the active material particles 12a.
  • the above-mentioned small voids are considered to originate mainly from the space between the crystal grains of the metal material 13 deposited on the surfaces of the active material particles 12a.
  • the large void mainly functions as a space for relieving stress caused by expansion and contraction of the active material particles 12a.
  • the small gap mainly serves as a path for supplying the non-aqueous electrolyte to the active material particles 12a.
  • the porosity can also be controlled by appropriately selecting the particle size of the active material particles 12a.
  • the particle 12a has a maximum particle size of preferably 30 ⁇ m or less, more preferably 10 ⁇ m or less.
  • the particle diameter of the particles is expressed by a D 50 value, it is preferably 0.1 to 8 ⁇ m, particularly preferably 0.3 to 4 ⁇ m.
  • the particle size of the particles is measured by laser diffraction / scattering particle size distribution measurement and electron microscope observation (SEM observation).
  • the thickness of the active material layer is preferably 10 to 40 ⁇ m, 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 0.25 ⁇ m or less, preferably 0.1 ⁇ m or less. There is no restriction
  • a secondary battery is assembled using the negative electrode 10 to reduce the overvoltage when the battery is initially charged. Can do. 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 a short circuit 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 in the surface and communicate with the active material layer 12. It is preferable.
  • the fine voids are preferably present in the surface layer so as to extend in the thickness direction of the surface layer. The fine voids allow the non-aqueous electrolyte to flow. The role of the fine voids is to supply a non-aqueous electrolyte into the active material layer 12.
  • the fine voids are such that the ratio of the area covered with the metal material 13, that is, the coverage is 95% or less, particularly 80% or less, especially 60% or less. It is preferable that the size is large. When the coverage exceeds 95%, it is difficult for the non-aqueous electrolyte having high viscosity to enter, and the range of selection of the non-aqueous electrolyte may be narrowed.
  • the surface layer is made of a metal material 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 made of two or more different metal materials. Considering 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 negative electrode 10 of the present embodiment has a high resistance to bending since 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. High folding resistance is extremely advantageous since the negative electrode 10 is less likely to be folded when the negative electrode 10 is folded or wound and accommodated in a battery container.
  • a film folding endurance fatigue tester product number 549) manufactured by Toyo Seiki Seisakusho is used, and measurement can be performed with a bending radius of 0.8 mm, a load of 0.5 kgf and a sample size of 15 ⁇ 150 mm. it can.
  • the current collector 11 in 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. It is preferable that the current collector 11 is made of the metal material having a low lithium compound forming ability described above. Examples of such metal materials are as already described. 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 a 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 (JIS C 2318) of 4% or more is also preferable to use. This is because when the tensile strength is low, wrinkles are generated due to stress when the active material expands, and when the elongation is low, the current collector may crack.
  • JIS C 2318 normal elongation
  • the thickness of the current collector 11 is preferably 9 to 35 ⁇ m considering the balance between maintaining the strength of the negative electrode 10 and improving the energy density.
  • a coating film is formed on the current collector 11 using a slurry containing particles of an active material and a binder, and then electrolytic plating is performed on the coating film.
  • 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 ⁇ m at the maximum height of the contour curve. If the maximum height exceeds 4 ⁇ m, the formation accuracy of the coating film 15 is lowered and current concentration of the permeation plating tends to occur on the convex portions. When the maximum height is less than 0.5 ⁇ m, the adhesion of the active material layer 12 tends to be lowered.
  • 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 in addition to the active material particles.
  • the slurry may contain a small amount of conductive carbon material particles such as acetylene black and graphite.
  • the conductive carbon material is preferably 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 uniform voids.
  • the content of the conductive carbon material exceeds 3% by weight, plating nuclei concentrate on the surface of the conductive carbon material, and it becomes difficult to form a good coating.
  • styrene butadiene rubber SBR
  • polyvinylidene fluoride PVDF
  • PE polyethylene
  • EPDM ethylene propylene diene 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 dilution 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 lithium compound forming ability. By immersion in the plating bath, the plating solution enters 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 plating metal species on the surfaces of the particles 12a (hereinafter, this plating is also referred to as permeation plating).
  • the osmotic plating is performed by using the current collector 11 as a cathode, immersing a counter electrode as an anode in a plating bath, and connecting both electrodes to a power source.
  • deposition of the metal material by permeation plating proceeds from one side of the coating film 15 to the other side. Specifically, as shown in FIGS. 2B to 2D, electrolytic plating is performed so that 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. I do.
  • electrolytic plating is performed so that 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. I do.
  • the conditions of the osmotic plating 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 already described.
  • the permeation plating 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.
  • the target negative electrode is obtained as shown in FIG.
  • the permeation plating is temporarily stopped when the metal material 13 is deposited in the entire thickness direction of the coating film 15, and then the type of the plating bath is changed. What is necessary is just to plate again and to form a surface layer on the coating film 15.
  • the negative electrode 10 it is also preferable to subject the negative electrode 10 to rust prevention after the osmotic plating.
  • rust prevention treatment for example, organic rust prevention using triazole compounds such as benzotriazole, carboxybenzotriazole, tolyltriazole, and imidazole, and inorganic rust prevention using cobalt, nickel, chromate and the like can be employed.
  • the measured values described so far are measured values at 20 ° C. unless otherwise specified.
  • Example 1 An average particle diameter (D 50) 8 [mu] m of lithium carbonate, the average particle diameter (D 50) 22 .mu.m of electrolytic manganese dioxide, an average particle diameter (D 50) 25 [mu] m of nickel hydroxide, the average particle diameter (D 50) 14 [mu] m of Cobalt oxyhydroxide was weighed so as to form a solid solution of (Li 1.00 Mn 0.20 Co 0.20 Ni 0.60 O 2 + 0.3Li 4/3 Mn 2/3 O 2 ) in a molar ratio. Water was added, and these were mixed and stirred to prepare a slurry having a solid content concentration of 50%.
  • a rotating disk was used for spraying, and granulation drying was performed by adjusting the temperature so that the rotation speed was 30000 rpm, the slurry supply amount was 2 kg / hr, and the outlet temperature of the drying tower was 120 ° C.
  • 500 g of the obtained granulated powder was filled in an alumina sagger and fired at 900 ° C. for 20 hours in the atmosphere using a stationary electric furnace (KBF-828N, manufactured by Koyo Thermo System Co., Ltd.).
  • the fired powder obtained by firing was classified with a sieve having an opening of 75 ⁇ m to obtain a lithium transition metal composite oxide powder (compound represented by the formula (1)).
  • the obtained powder was analyzed by ICP to confirm the desired composition. Further, it was confirmed by X-ray diffraction (MXP18II manufactured by Bruker AXS Co., Ltd.) that this powder was a single solid solution. The X-ray diffraction results are shown in FIG.
  • This lithium transition metal oxide powder was used as a positive electrode active material.
  • This positive electrode active material was kneaded with acetylene black (AB), polyvinylidene fluoride (PVdF), and N-methylpyrrolidone as a solvent using a stirring deaerator (manufactured by Kurashiki Boseki Co., Ltd., Mazerustar KK-50). Thus, a positive electrode mixture was obtained.
  • This positive electrode mixture was applied to one side of a current collector made of aluminum foil (thickness 20 ⁇ m) using an applicator and dried at 120 ° C., followed by roll pressing with a load of 0.5 ton / cm to obtain a positive electrode. .
  • the gap of the applicator was adjusted so that the thickness of the positive electrode was 50% with respect to the theoretical capacity of the negative electrode. As a result, the thickness was 48%.
  • the positive electrode was punched into a diameter of 13 mm, and battery characteristics were evaluated.
  • a current collector made of an electrolytic copper foil having a thickness of 18 ⁇ m was acid washed at room temperature for 30 seconds. After the treatment, it was washed with pure water for 15 seconds. On one side of the current collector, a slurry containing silicon particles was applied to a film thickness of 15 ⁇ m to form a coating film.
  • the average particle diameter D 50 of the particles was 2 ⁇ m.
  • the average particle diameter D 50 was measured using a Microtrac particle size distribution measuring apparatus (No. 9320-X100) 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 copper was permeated to the coating film by electrolysis to form an active material layer.
  • the electrolysis conditions were as follows. DSE was used for the anode. A DC power source was used as the power source. Copper pyrophosphate trihydrate: 105 g / l -Potassium pyrophosphate: 450 g / l ⁇ Potassium nitrate: 30 g / l -P ratio: 7.7 ⁇ Bath temperature: 50 ° C ⁇ Current density: 3 A / dm 2 -PH: Ammonia water and polyphosphoric acid were added to adjust to pH 8.2.
  • the permeation plating was terminated when copper was deposited over the entire thickness direction of the coating film. In this way, a target negative electrode was obtained.
  • SEM observation of the longitudinal section of the active material layer confirmed that the active material particles were covered with a copper film having an average thickness of 240 nm in the active material layer.
  • the porosity of the active material layer was 30%.
  • the obtained negative electrode was punched into a diameter of 14 mm. It was 10.9 mAh when the theoretical capacity
  • the particle diameter D 50 of the raw material and the positive electrode active material was measured by the following method. Using a sample circulator for laser diffraction particle size distribution analyzer (“Microtarac SDC” manufactured by Nikkiso Co., Ltd.), the sample (powder) was put into water and irradiated with ultrasonic waves of 40 W at a flow rate of 80% for 360 seconds. Subsequently, the particle size distribution was measured using a laser diffraction particle size distribution measuring instrument “MT3000” manufactured by Nikkiso Co., Ltd. The particle size D 50 was determined from the obtained volume-based particle size distribution chart.
  • a sample circulator for laser diffraction particle size distribution analyzer (“Microtarac SDC” manufactured by Nikkiso Co., Ltd.
  • the particle size distribution was measured using a laser diffraction particle size distribution measuring instrument “MT3000” manufactured by Nikkiso Co., Ltd.
  • the particle size D 50 was determined from the obtained volume-based particle size distribution chart.
  • the negative electrode active material was measured in the same manner as the raw material and the positive electrode active material except that the apparatus was used and the particle permeability condition was used as reflection.
  • Example 2 An average particle diameter (D 50) 8 [mu] m of lithium carbonate, the average particle diameter (D 50) 22 .mu.m of electrolytic manganese dioxide, an average particle diameter (D 50) 25 [mu] m of nickel hydroxide, the average particle diameter (D 50) 14 [mu] m of Cobalt oxyhydroxide was weighed so as to form a solid solution (Li 1.00 Mn 0.20 Co 0.20 Ni 0.60 O 2 + 0.2Li 4/3 Mn 2/3 O 2 ) in a molar ratio. Water was added and mixed and stirred to prepare a slurry having a solid content concentration of 50%.
  • lithium transition metal composite oxide powder (compound represented by the formula (1)) was obtained.
  • the obtained powder was analyzed by ICP to confirm the desired composition. Further, it was confirmed by X-ray diffraction (MXP18II manufactured by Bruker AXS Co., Ltd.) that this powder was a single solid solution.
  • a 2032 type coin battery was manufactured from the positive electrode thus obtained using the same negative electrode and separator as in Example 1 and in the same procedure as in Example 1.
  • Example 1 The composition of the positive electrode active material and LiCoO 2, the raw material powder at the time of slurry preparation 1.5 kg, water 3.5 kg, a dispersing agent and 190 g, except that the firing temperature 1000 ° C. in the same manner as in Example 1 A positive electrode active material and a positive electrode were obtained. A 2032 type coin battery was manufactured from the positive electrode thus obtained using the same negative electrode and separator as in Example 1 and in the same procedure as in Example 1.
  • Example 2 A positive electrode active material and a positive electrode were obtained in the same manner as in Example 1 except that the composition of the positive electrode active material was Li 1.06 Mn 0.31 Co 0.31 Ni 0.32 O 2 and the firing temperature was 975 ° C. A 2032 type coin battery was manufactured from the positive electrode thus obtained using the same negative electrode and separator as in Example 1 and in the same procedure as in Example 1.
  • ⁇ Discharge after pre-charging Constant current mode, rate 0.01C, end voltage 2.7V ⁇
  • First to fourth charge After charging to 4.2 V with a constant current of 0.1 C, the voltage is set to a constant potential from 4.2 V, and the process ends when the current value reaches 1/10 of the constant current value.
  • ⁇ First to fourth discharge Constant current mode, rate 0.1C, end voltage 2.7V ⁇ 5th and later charging: After charging to 4.2 V with a constant current of 0.5 C, the voltage is set to a constant potential from 4.2 V, and the process ends when the current value reaches 1/10 of the constant current value.
  • ⁇ 5th and subsequent discharges Constant current mode, rate 0.5C, end voltage 2.7V
  • the secondary battery of the example using the lithium transition metal composite oxide represented by the formula (1) as the positive electrode active material is a comparative example using a conventional positive electrode active material. It can be seen that the cycle characteristics are good and the capacity is higher than that of the secondary battery.
  • the positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention the high capacity characteristics of the negative electrode active material containing Si or Sn can be fully utilized. Further, a secondary battery using these active materials can have a long life.

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Abstract

La présente invention a trait à un matériau actif d'électrode positive pour une batterie rechargeable à électrolyte non aqueux, caractérisé en ce que le matériau comprend un oxyde composite de métal de transition de lithium représenté par la formule (1) suivante, le matériau actif d'électrode positive étant utilisé en association avec un matériau actif d'électrode négative comprenant Si ou Sn. Le composé représenté par la formule (1) comprend une solution solide représentée par la formule (2) suivante. Li1+x(MnαCoβNiγ)1-xO2 aLi4/3Mn2/3O2 (2). La présente invention a également trait à une batterie rechargeable à électrolyte non aqueux, comprenant une électrode positive comprenant le matériau actif d'électrode positive et une électrode négative comprenant un matériau actif d'électrode négative comprenant Si ou Sn. Une couche de matériau actif d'électrode négative contient des particules du matériau actif comprenant Si ou Sn. Au moins une partie de la surface de la particule est recouverte d'un matériau métallique présentant une faible capacité de formation d'un composé de lithium et un espace est formé entre les particules recouvertes par le matériau métallique.
PCT/JP2008/070434 2007-12-27 2008-11-10 Matériau actif d'électrode positive pour batterie rechargeable à électrolyte non aqueux et batterie rechargeable à électrolyte non aqueux comprenant le matériau actif d'électrode positive Ceased WO2009084330A1 (fr)

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JP2007338268A JP2009158415A (ja) 2007-12-27 2007-12-27 非水電解液二次電池用正極活物質及びそれを有する非水電解液二次電池
JP2007-338268 2007-12-27

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JP5733550B2 (ja) * 2010-02-26 2015-06-10 トヨタ自動車株式会社 リチウムイオン二次電池
JP5099168B2 (ja) * 2010-04-16 2012-12-12 株式会社豊田自動織機 リチウムイオン二次電池
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CN102792493B (zh) * 2010-09-14 2015-03-11 日立麦克赛尔株式会社 非水二次电池
JP2012142154A (ja) 2010-12-28 2012-07-26 Sony Corp リチウムイオン二次電池、電動工具、電動車両および電力貯蔵システム
JP2012142157A (ja) * 2010-12-28 2012-07-26 Sony Corp リチウムイオン二次電池、正極活物質、正極、電動工具、電動車両および電力貯蔵システム
JP2012142155A (ja) 2010-12-28 2012-07-26 Sony Corp リチウム二次電池、正極活物質、正極、電動工具、電動車両および電力貯蔵システム
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JP2014086218A (ja) * 2012-10-22 2014-05-12 Toyota Motor Corp 全固体電池システム
WO2014181455A1 (fr) * 2013-05-10 2014-11-13 株式会社 日立製作所 Matériau actif d'électrode positive pour une pile rechargeable non aqueuse, électrode positive pour une pile rechargeable non aqueuse qui utilise ce matériau, pile rechargeable non aqueuse et procédé permettant de fabriquer cette dernière
WO2015019483A1 (fr) * 2013-08-09 2015-02-12 株式会社日立製作所 Matériau actif d'électrode positive pour batteries secondaires à électrolyte non aqueux, électrode positive pour batteries secondaires à électrolyte non aqueux l'utilisant, et batterie secondaire à électrolyte non aqueux
US10340514B2 (en) 2013-08-23 2019-07-02 Nec Corporation Negative electrode for lithium ion secondary battery, and lithium ion secondary battery
WO2015111187A1 (fr) * 2014-01-24 2015-07-30 日産自動車株式会社 Dispositif électrique
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JP2017174523A (ja) * 2016-03-22 2017-09-28 株式会社日立製作所 リチウムイオン二次電池
US10122042B2 (en) * 2017-01-12 2018-11-06 StoreDot Ltd. Increasing cycling lifetime of fast-charging lithium ion batteries
JP6904393B2 (ja) * 2019-09-19 2021-07-14 Tdk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及びリチウムイオン二次電池の製造方法
WO2022137346A1 (fr) * 2020-12-22 2022-06-30 ＴｅｒａＷａｔｔ Ｔｅｃｈｎｏｌｏｇｙ株式会社 Système de batterie, dispositif de charge et procédé de charge
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CN113437261A (zh) * 2021-06-22 2021-09-24 中国电力科学研究院有限公司 一种普鲁士蓝类正极片、钠离子电池及制备方法

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