WO2004034491A1 - 非水電解質二次電池、及びこの非水電解二次電池に用いる正極の製造方法 - Google Patents
非水電解質二次電池、及びこの非水電解二次電池に用いる正極の製造方法 Download PDFInfo
- Publication number
- WO2004034491A1 WO2004034491A1 PCT/JP2003/012906 JP0312906W WO2004034491A1 WO 2004034491 A1 WO2004034491 A1 WO 2004034491A1 JP 0312906 W JP0312906 W JP 0312906W WO 2004034491 A1 WO2004034491 A1 WO 2004034491A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- graphite
- positive electrode
- cycle
- secondary battery
- electrolyte secondary
- Prior art date
Links
Classifications
-
- 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
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light 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
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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 non-aqueous electrolyte secondary battery, and a method for producing a positive electrode used in the non-aqueous electrolyte secondary battery.
- the present invention relates to a non-aqueous electrolyte secondary battery in which a graphite material is used as a positive electrode, lithium metal or an alloy thereof or a material capable of inserting and extracting lithium as a negative electrode, and a non-aqueous electrolyte containing a lithium salt as an electrolyte, and The present invention relates to a method for producing a positive electrode used for the nonaqueous electrolyte secondary battery.
- non-aqueous electrolyte secondary batteries have high energy densities that can be stored and have been used for various applications.However, when a predetermined charge / discharge cycle is reached, it is difficult to continue using them, or they are not used. It had the disadvantage of falling into a possible state.
- the present inventors have proposed a positive electrode made of a graphite material, a non-aqueous electrolyte containing a lithium salt, and lithium metal or lithium for the purpose of improving the charge and discharge cycle life of this type of secondary battery. Focused on a non-aqueous electrolyte secondary battery equipped with a negative electrode made of a material that can be extracted, we conducted intensive research.
- a nonaqueous electrolyte secondary battery including a positive electrode made of a graphite material, an electrolyte containing a lithium salt, and a negative electrode made of lithium metal has been known for a long time. Attempts have also been made to improve the cycle characteristics by applying a carbon material capable of inserting and extracting lithium as the negative electrode of the battery (for example, Japanese Patent Application Laid-Open Nos. 61-7567 (Patent Document 1), — See 82 4 66 (Patent Document 2). Lithium metal depends on charge and discharge cycle This is because the cycle life is short as a result of repeated dissolution / precipitation, generation of dendrites and passivation.
- the non-aqueous electrolyte secondary battery configured as described above is assembled in a normal discharge state, and cannot be discharged unless it is charged.
- the charge / discharge reaction will be described below, taking as an example the case where a graphite material capable of reversibly inserting and extracting lithium is used as the negative electrode.
- the anion in the electrolyte is stored in the positive electrode (graphite material) and the cation (lithium ion) is stored in the negative electrode (inter-force).
- the negative electrode a donor-type graphite intercalation compound is formed, respectively.
- the cations and anions occluded in both electrodes are released (intercalation), and the battery voltage drops.
- the charge / discharge reaction can be expressed as the following equation.
- the positive electrode in this type of secondary battery utilizes a reaction in which the sceptor-type graphite intercalation compound is reversibly formed by the electrolyte anion during charge and discharge.
- Examples of such a positive electrode material include graphitized carbon fibers (see, for example, JP-A-61-10882 (Patent Document 3)) and expanded graphite sheets (JP-A-63).
- Patent Document 4 Japanese Patent Laid-Open No.
- Patent Document 5 Patent No. 366554 (Patent Document 5)
- plastic-reinforced graphite, natural graphite powder, pyrolytic graphite, graphitized vapor-grown carbon fiber, and PAN-based carbon fiber have been studied. Disclosure of the invention
- this type of battery has a disadvantage that the discharge capacity is deteriorated every time the charge / discharge cycle is repeated. This is mainly due to the deterioration of the cathode material. In other words, as the charge / discharge cycle is repeated, anion having a relatively large molecular size is repeatedly absorbed and released into the graphite material, causing the graphite crystal to collapse and causing cracks in the particles. This is because it changes to an impossible form.
- the term “graphitization” refers to a phase transition due to thermal energy from amorphous carbon to graphite, and more specifically, 170 ° C. regardless of the degree of crystallinity after graphitization. This means that heat treatment is performed at the above temperature (power dictionary).
- carbon material refers to a solid substance containing carbon atoms as a main component, and does not specify the regularity of the arrangement.
- graphite powder refers to a solid substance containing a carbon atom as a main component and having a crystal structure in which the carbon atoms are arranged with three-dimensional regularity. It is irrelevant whether or not the material is used.
- the average particle size is defined as a general range of about 1 to 100 m.
- the present invention has been made in view of the above problems, and has as its object to use a non-aqueous electrolyte secondary battery having a large capacity and extremely excellent cycle characteristics, and a non-aqueous electrolyte secondary battery.
- An object of the present invention is to provide a method for manufacturing a positive electrode.
- a non-aqueous electrolyte secondary battery according to the first invention according to claim 1 of the present application includes a positive electrode made of graphite powder,
- a negative electrode made of a material capable of occluding and releasing metal or lithium is opposed via an electrolyte containing a lithium salt, the positive electrode was measured by powder X-ray diffraction method.
- the crystallite size L c (1 1 2) in the c-axis direction calculated from the (1 1 2) diffraction line of the graphite crystal is 4 nm to 30 nm, and the graphite of the positive electrode filled in the battery
- the charge capacity in the first cycle based on the total weight of the material is 50 (mAh / g) or less.
- Ordinary synthetic graphite powder is prepared by mixing organic materials such as petroleum pitch, coal tar pitch, condensed polycyclic hydrocarbon compounds, and organic polymer compounds in an atmosphere of inert gas such as nitrogen or argon gas or helium gas. After carbonization at 000 ° C, it is further heat-treated (graphitized) at 250 ° C or more, preferably 300 ° C or more, and pulverized. Graphite powder made from naturally occurring natural graphite material is refined by ore-crushing ores containing massive graphite, and is repeatedly purified by flotation, and is further manufactured by grinding and adjusting the particle size.
- the degree of the development of such graphite crystals is defined by the crystallite size L c (111) in the c-axis direction.
- the number of molecules of the intercalating layer constituting the intercalating layer tends to increase as the degree of graphitization increases, that is, as the crystallite size increases. If the crystallinity decreases, lattice defects increase, and it becomes difficult for ayuon to intercalate in that region. Therefore, it is possible to control the number of molecules of the inter-rate layer according to the crystallinity, that is, the size of the crystallite.
- the capacity deterioration due to the repetition of the charge / discharge cycle is the collapse of graphite crystals caused by the reversible intercalation of the anion, but the inventors have found that the number of molecules in the intermittent rate layer is slightly reduced.
- the crystal development is insufficient, the charge / discharge capacity, that is, the number of anions capable of intercalation in the graphite crystal decreases, and even if the charge / discharge is performed at a lower capacity, the crystal will not Crystal structure collapse occurs due to incomplete structure, and cycle deterioration cannot be suppressed.
- the crystallites are slightly smaller than the crystal structure of perfect graphite, and that some lattice defects are introduced.
- the crystal growth is insufficient and the crystallite is too small Is not preferred.
- the plane distance d (002) between adjacent hexagonal mesh planes of the graphite crystal is about 0.335 nm, while the ion radius of the anion is about 0.7 to 0.9 nm. Therefore, the relative position between adjacent hexagonal mesh planes changes greatly due to the interlocking of the graphite materials. Such a change in the relative position is accumulated as the charge / discharge cycle is repeated, resulting in an irreversible change. Such a phenomenon is also an irreversible change in the crystal structure. If the changed area increases, the area where the anion can perform reversible in-force reduction decreases, causing cycle deterioration.
- the crystallinity is evaluated as L c (1 1 2), and the range is 4 330 nm.
- L c (112) is larger than 30 nm, the capacity obtained within a predetermined potential range is large, but the cycle deterioration is undesirably large.
- the charge capacity in the first cycle based on the total weight of the positive electrode filled in the battery is 20 to 50 ( m A h / g).
- the charging / discharging reaction mechanism of the positive electrode of the nonaqueous electrolyte secondary battery specified in the present application is a reversible intercalation reaction of anion as described above, but the average operating potential is the charge capacity in the first cycle. Varies depending on That is, the larger the charge capacity in the first cycle, the higher the average operating potential is, and the smaller the charge capacity, the lower the average operating potential.
- the anion present in the electrolyte is occluded between the graphite layers, and then when discharging, the anion is released into the electrolyte, but in the first cycle, a large irreversible capacity is obtained. appear.
- the charge and discharge efficiency after the second cycle is 100 ° / °. A value close to is obtained.
- the charge and discharge efficiency in the first cycle varies depending on various physical properties of the graphite material, but is generally lower than the charge and discharge efficiency in the second and subsequent cycles.
- the charge / discharge efficiency in the first cycle changes depending on the charge capacity in the first cycle, and decreases as the capacity increases.
- the electric capacity corresponding to the irreversible capacity is stored in a state that cannot be released by electrochemical methods (discharge-disabled state) while the ayuon is intercalated between the graphite layers, and so-called “residual compounds”. Has formed.
- the larger the charge capacity in the first cycle the larger the irreversible capacity generated in the first cycle is that the larger the charge capacity in the first cycle, the larger the residual compound formed in the first cycle. Is large.
- the potential of the positive electrode is determined by the amount of anion absorbed between the graphite layers. The average operating potential will shift to noble.
- the obtained charging and discharging capacity becomes inevitably smaller as the charging capacity in the first cycle is increased. If the charge capacity in the first cycle is larger, the operating potential in the subsequent charge and discharge shifts to noble, and if the same capacity is to be obtained, the larger the charge capacity in the first cycle, the more the charge This is because the voltage must be set high. As described above, when the reversible interaction of the anion is used for the positive electrode, the charge capacity S in the first cycle and the subsequent charge-discharge characteristics are greatly affected. It is very important to define the capacity.
- the charge capacity in the first cycle is too large, the charge voltage required to obtain a predetermined charge / discharge capacity increases, and oxidative decomposition of the electrolyte tends to occur, resulting in large cycle deterioration. Is not preferred. Also, as described above, even when charging and discharging are performed within a predetermined potential range, If the charge capacity in the first cycle is too large, the discharge capacity obtained in the second and subsequent cycles becomes small, which is not preferable.
- the first invention of the present application is that the charge capacity in the first cycle based on the weight of the positive electrode present on the surface of the graphite material of the positive electrode facing the negative electrode is 20 to 50 mAhZg. It was stipulated.
- the capacity of the positive electrode per unit weight can be calculated as a value obtained by dividing the charge capacity of the entire battery by the total weight of the positive electrode filled in the battery.
- the non-aqueous electrolyte secondary battery according to claim 1, wherein) is 20 or less.
- Graphite crystallites are in a state where hexagonal mesh planes composed of carbon atoms are stacked with three-dimensional regularity, but the bonds between the carbon atoms that compose the hexagonal mesh planes are benzene ring-shaped.
- the bond between hexagonal mesh planes is only weak Van der Waals force, and the shape and properties of crystallites are rich in anisotropy.
- shear deformation occurs along the layer surface in the initial stage of pulverization, reflecting the very weak bond between the graphite layers, resulting in a rhombohedral structure. Appear.
- the bonding force (van der Waals force) between adjacent hexagonal mesh planes is weak between layers composed of such undulating hexagonal mesh planes, and the crystal lattice collapses when electrolyte anions intercalate.
- the capacity deteriorates as the charge / discharge cycle progresses, which is not preferable.
- Exists inside the particle This is because the ratio of the volume space occupied by the layers including the layer surface existing on the particle surface to the volume space occupied by the crystal layers is large, and the capacity of the cycle deterioration by the ratio cannot be ignored.
- the specific surface area (hereinafter referred to as the BET surface area) calculated by the nitrogen adsorption method can reflect the undulating shape of the particle surface as an increase in the surface area. It is difficult to specify whether the change is due to the diameter or the undulating shape of the surface. Therefore, the inventors have found that it is possible to evaluate the undulating shape of the particles by comparing the surface area calculated from the particle size distribution with the BET surface area, and have completed the second invention of the present application. Reached.
- the “surface area determined from the area average diameter” defined in the second invention of the present application is defined as the particle diameter measured by a laser diffraction type particle size distribution analyzer and the area average diameter calculated from the number thereof. It is the calculated surface area (m 2 / g).
- D is the area average diameter calculated by Equation 5 below.
- Equation 4 is the surface area (m 2 / g) based on the mass of the particles. Since the unit of the specific surface area obtained by the nitrogen adsorption (BET) method is also (m 2 Zg), the ratio specified in the second invention of the present application, that is, the specific surface area obtained by the nitrogen adsorption (BET) method The unit of the ratio between A and the surface area B calculated from the area average diameter is dimensionless.
- the graphite powder of the positive electrode is specifically defined by the distortion of the crystal lattice, so that the influence on the crystal lattice given by a pulverizing operation and the influence on the charge / discharge capacity is reduced. Clarified. Although it is different from the second invention in which the particle surface is damaged by pulverization, the effect of mechanical energy given by pulverization etc. on the charge and discharge capacity of the positive electrode is exactly the same, and the effect of the third invention Is the same as the effect of the second invention.
- the graphite powder of the positive electrode specified in the first invention and the second invention has an intensity of a diffraction line corresponding to the (006) plane obtained by the X-ray wide-angle diffraction method.
- the lattice distortion between adjacent hexagonal mesh planes corresponds to the (006) plane obtained by X-ray wide-angle diffraction. It can be evaluated by the intensity ratio I (004) ZI (006) of the intensity I (004) of the diffraction line corresponding to the (004) plane to the intensity I (006) of the diffraction line.
- the crystallite size L c (004) in the c-axis direction obtained from the (004) diffraction line is obtained from the (00 2) diffraction line
- a value smaller than the crystallite size L c (00 2) in the c-axis direction is obtained.
- it is smaller than the value using lower-order diffraction lines. Normal. This is thought to be due to the fact that the layer lattice of actual carbon is not in the ideal state, and that the crystal lattice is distorted.
- the (0 04) diffraction line and the (006) diffraction line specified in the present application are both diffraction lines derived from the secondary and tertiary reflection from the (002) plane, the lattice distortion between adjacent hexagonal mesh planes Is small, the relative intensity of the (006) diffraction line to the (004) diffraction line increases, and the intensity ratio I (0 04) ZI (00 6) decreases. If this value is 15 or more, the lattice strain is too large, and the reversible storage / release capacity decreases as the charge / discharge cycle progresses. This is because, when anion is repeatedly inserted and extracted into a graphite material having a large lattice strain, its crystal structure is likely to be irreversibly changed, and the crystal region in a chargeable / dischargeable state is reduced.
- the method for producing a positive electrode used in the nonaqueous electrolyte secondary battery of the fourth invention according to claim 4 of the present application comprises the positive electrode in the nonaqueous electrolyte secondary battery of claims 1 to 3 described above.
- the method for producing the graphite powder was specifically defined. That is, the invention according to claim 4 of the present application is the method for producing a positive electrode used in the non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the graphite powder of the positive electrode is easily graphitizable. It is necessary to grind at least one material selected from carbon materials or its starting materials or carbon precursors to an average particle size of 50 ⁇ m or less, and heat-treat them in an inert gas atmosphere to graphitize them.
- the essence of this production method is that when obtaining graphite powder, a pulverization treatment is performed at the stage of the starting raw material before the graphitization treatment, and after the graphitization, the pulverization is only enough to introduce strain into the crystal structure. That is not done.
- the graphite powder produced by such a method has less distortion present in the crystal structure and a relatively small molecular size compared to graphite powder that has been subjected to a graphitization treatment in a lump state and then crushed and adjusted in particle size.
- the crystal structure is not easily collapsed even if a large anion is engaged.
- pitches such as coal tar pitch or petroleum pitch are representative. These pitches can be obtained through purification or reforming processes such as distillation, extraction, pyrolysis, and dry distillation of raw materials such as coal tar or crude oil.
- organic polymer compounds such as condensed polycyclic polynuclear aromatic (C0PNA resin) and polychlorinated vinyl resin using aromatic compounds such as naphthalene, phenanthrene, anthracene, pyrene, perylene, and acenaphthylene can also be used. It is.
- an anisotropic region is formed to generate a carbon precursor.
- the precursor is in a state where it can easily give a graphite material by a subsequent heat treatment.
- the anisotropic region is called a carbonaceous mesophase, and the larger the anisotropic region (ie, the closer to the bulk mesomorphous state), the more graphite material having a high crystal structure integrity after graphitization is obtained. Therefore, it is particularly preferable as a raw material of the graphite powder specified in the present invention.
- the obtained carbon materials such as mesophase pitch-based carbon fiber, pyrolyzed carbon, mesocarbon microbeads, pitch coaters or petroleum coaters, and needle coaters are also graphitizable carbon materials. It is suitable as a starting material for the graphite powder specified in the present invention.
- One or more materials selected from the above graphitizable carbon materials or their starting materials or carbon precursors are pulverized to an average particle diameter of 100 m or less before graphitization.
- the reason for this is that the electrode mixture must be molded without pulverization after the graphitization treatment.
- the positive electrode mixture is kneaded with the graphite material after the graphitization treatment and a binder, and in some cases, a conductive agent to form an electrode mixture. It is molded into a predetermined size and assembled into a battery. In order to mold such an electrode mixture into a desired size, it is necessary to use graphite powder having an average particle diameter of at least 100 m or less.
- the average particle diameter means a volume average diameter (cumulative volume 50% diameter: d50), which is essentially different from the area average diameter used in claim 3.
- the average particle diameter of the raw material powder before the graphitization treatment is preferably as small as possible, preferably 30 ⁇ m or less, more preferably 10 ⁇ m, in consideration of the positive electrode characteristics of the graphite powder after the graphitization treatment. m, particularly preferably 5 ⁇ m or less. The finer the raw material powder before the graphitization treatment is, the higher the ratio of Ethium to the total surface area of the graphite powder after the graphitization treatment is, and the more smoothly the anion intercalation reaction proceeds. The anion intercalates into the crystal structure from the edge of graphite.
- any conventional pulverizer such as a pin mill, a pole mill, and a colloid mill can be used. is there.
- Graphitization after pulverization is carried out in an inert gas atmosphere at a temperature of 2400 ° C. or more, preferably Lc (1 12) of the graphite powder after the graphitization treatment is 4 to 30 nm.
- the heat treatment may be performed at a temperature of about 300 ° C.
- the fifth invention of the present application specifies a simple processing means for making graphite powder pulverized after graphitization usable as a positive electrode material. That is, the fifth invention of the present application is characterized in that a graphite powder having an average particle size of 50 / xm or less is heat-treated at 170 ° C. or more in an inert gas atmosphere, Is the way.
- the unit cell of the graphite crystal is hexagonal, but when such hexagonal graphite is crushed, shear deformation occurs along the layer surface and a rhombohedral structure appears.
- carbon-carbon bonding in the layer plane In this case, the mechanical energy provided by the grinding is accumulated by the introduction of the rhombohedral structure, with some flat hexagonal mesh planes shifted.
- the existence ratio of such rhombohedral and hexagonal structures can be verified by examining the intensity ratio of the diffraction peaks obtained by the X-ray wide-angle diffraction method.
- the diffraction angle (2 ⁇ / ⁇ ) may be run around 40 to 50 ° (hereinafter simply referred to as rounding).
- rounding When the angle is expressed as a bending angle, it is assumed that the measurement is performed with a Geiger-flex type powder X-ray wide-angle diffractometer using steel for the tube.
- the positive electrode thus obtained is kneaded and formed together with a conductive agent and a binder, and is incorporated into a battery as a positive electrode mixture.
- the positive electrode material according to the present invention originally has high conductivity and does not require a conductive agent or the like, it may be used as necessary in consideration of the application of the battery.
- the conductive agent various graphite materials and carbon black have been widely used.
- the graphite material functions as a positive electrode, and thus it is not preferable to apply the conductive material as a conductive agent. Therefore, it is preferable to use conductive carbon blacks.
- the carbon black used here may be any of channel black, oil furnace black, lamp black, therma / reblack, acetylene black, ketjen black, and the like.
- car pump racks other than acetylene black use a part of petroleum pitch or coal tar pitch as a raw material, and may contain a large amount of impurities such as sulfur compounds or nitrogen compounds. It is preferable to use after removing impurities.
- acetylene black uses only acetylene as a raw material and is produced by a continuous pyrolysis method, so it is difficult for impurities to be mixed in, and the chain structure of particles is remarkably developed, so that it has excellent liquid retention and electrical resistance. Is particularly preferred as this type of conductive agent.
- the mixing ratio of the conductive agent and the graphite material according to the present invention may be appropriately set according to the use of the battery. Especially when the requirements for the completed battery include improvement in rapid charge characteristics and heavy load discharge characteristics, the requirement for the effect of imparting conductivity together with the graphite material of the present invention is sufficiently obtained. It is more preferable to mix a conductive agent in the above to form a positive electrode mixture. However, if the conductive agent is contained more than necessary, it is not preferable because the amount of the cathode material to be filled decreases accordingly and the capacity (volume energy density) decreases. As the binder, it does not dissolve in the electrolytic solution and has excellent solvent resistance.
- PVdF polyvinylidene fluoride
- PTFE polytetrafluoroethylene
- PVF polyvinylinole
- Organic polymer compounds such as carboxymethyl cellulose, polyimide resin, polyamide resin, polyacrylic acid and sodium polyacrylate are suitable.
- the positive electrode mixture is constituted by using a binder, and if necessary, a conductive agent and the like, mixed and molded, and then incorporated into a battery.
- any material can be used for the negative electrode as long as it can occlude and release lithium ions electrochemically.
- lithium metal Richiumua Ruminiumu alloy, graphite material, the graphitizable carbon material, non-graphitizable carbon materials, niobium pentoxide (N b 2 O 5), lithium titanate (L i 4 T i 5 ⁇ 1 2 ), silicon monoxide (S i 0), monoxide tin (S n 0), a composite oxide of tin and lithium (L i 2 S N_ ⁇ 3), lithium 're down. composite oxide of boron (e.g., L i P Q. 4 B .. 6 0 2. 9), and the like.
- boron e.g., L i P Q. 4 B .. 6 0 2. 9
- carbon materials include various graphite materials such as natural graphite, synthetic graphite, and expanded graphite that have been appropriately pulverized, carbonized mesocarbon microphone mouth beads, mesophase pitch-based carbon fiber, and the like.
- Carbon materials such as vapor-grown carbon fiber, pyrolytic carbon, petroleum coke, pitch coke and needle coat, And a synthetic graphite material obtained by subjecting these carbon materials to graphitization, or a mixture thereof.
- the negative electrode is also formed by mixing and molding the above-listed materials, a binder, and if necessary, the above-mentioned conductive agent, etc., to form a negative electrode mixture, and then incorporating the negative electrode mixture into the battery.
- the binder and the conductive agent the materials exemplified above can be used as they are when producing the positive electrode mixture.
- non-aqueous electrolyte examples include a non-aqueous electrolyte in which a lithium salt is dissolved in an organic solvent, and a solid electrolyte in which a lithium salt is dissolved in a lithium ion conductive solid substance.
- the nonaqueous electrolyte is prepared by dissolving a lithium salt in an organic solvent, and any of these organic solvents and lithium salts can be used as long as they are used in this type of battery.
- a lithium salt for example, propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), ⁇ -petit mouth ratatotone (GBL), vinylene carbonate (VC),
- PC propylene carbonate
- EC ethylene carbonate
- BC butylene carbonate
- GBL ⁇ -petit mouth ratatotone
- VC vinylene carbonate
- Examples include acetoethryl (AN), dimethyl carbonate (DMC), getyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and derivatives thereof, or a mixed solvent thereof.
- the sixth invention of the present application is characterized in that the electrolyte of the nonaqueous electrolyte secondary battery specified in the first invention to the third invention is a nonaqueous electrolyte in which a lithium salt is dissolved in these nonaqueous solvents.
- Vinylene carbonate (hereinafter abbreviated as VC) is a cyclic carbonate such as propylene carbonate (PC) or ethylene carbonate (EC), or a linear carbonate such as dimethyl carbonate (DMC) or getyl.
- Carponate (DEC) ethyl methyl carbonate Oxidation decomposition voltage is lower than that of boronate (EMC), etc., and a clear oxidative decomposition reaction can be observed in a potential region more noble than 4.9 (VV s Li + / L i) even at 25 ° C You can check.
- VC is considered to be more easily oxidized and decomposed than the above-mentioned other cyclic or chain carbonates.
- the present inventors have found that in the case of an axceptor-type graphite intercalation compound, which is a charge product of the positive electrode, once, When the oxidative decomposition reaction of VC occurs, a passivation film is formed on the surface of the particles, and the film suppresses further oxidative decomposition, and as a result, the oxidative decomposition voltage is higher than that of the other cyclic or chain carbonates.
- the oxidative decomposition reaction caused by these factors can be suppressed at the same time, and the cycle characteristics of this type of nonaqueous electrolyte secondary battery can be improved.
- the thickness of the passive body film formed on the particle surface is proportional to the volume ratio of VC based on the total volume of the non-aqueous solvent.
- VC itself is further oxidatively decomposed and the oxidative decomposition reaction of other cyclic or chain carbonates cannot be suppressed at the positive electrode in the charging process.
- the volume is more than 10 volume ° / 0 , the formed immobile body film is too thick, which inhibits the charge / discharge reaction, that is, the reversible interaction reaction of the electrolyte anion, and significantly lowers the charge / discharge capacity. It is not preferable because the resistance polarization increases as the charge / discharge cycle progresses, which causes cycle deterioration.
- the volume ratio of VC to the total volume of the nonaqueous solvent is limited to 0.1 to 10% by volume.
- any lithium salt can be used as long as it is used for this type of battery.
- the amount of these salts dissolved in the organic solvent may be appropriately set in the range of 0.5 to 4.0 (mo1 / L) as in the case of the conventional nonaqueous electrolyte secondary battery, but is preferably used. Is from 0.8 to 3.5 (mo 1 ZL), more preferably from 1.0 to 30 (mol / L).
- the non-aqueous electrolyte secondary battery to which the present invention is applied by arranging the positive electrode part and the negative electrode part configured as described above in a closed container via a non-aqueous electrolyte in which a lithium salt is dissolved, Is completed.
- FIG. 1 is a cross-sectional view of a test cell.
- FIG. 2 is a view showing the structure of a single 18650 type wound lithium secondary battery.
- FIG. 3 is a diagram showing the relationship between L c (1 12) of the graphite material, the initial discharge capacity, and the capacity retention after 100 cycles.
- FIG. 4 is a view showing a discharge carp of graphite C.
- FIG. 5 is a diagram showing a discharge curve of graphite V.
- FIG. 6 shows a discharge curve of graphite Q.
- FIG. 7 is a diagram showing a discharge curve of graphite L.
- FIG. 8 is a diagram showing a discharge curve of graphite R.
- FIG. 9 is a diagram showing a discharge curve of graphite M.
- FIG. 10 is a diagram showing a discharge curve of graphite N.
- FIG. 11 is a diagram showing a discharge curve of graphite O.
- Figure 12 shows the relationship between the A / B value and the capacity retention rate after 100 cycles.
- FIG. 13 is a diagram showing a relationship between I (004) / 1 (06) and the capacity retention ratio after 100 cycles.
- FIG. 14 is a diagram showing the relationship between the charge capacity of the first cycle of graphite Q, the initial cycle discharge capacity, and the capacity retention rate after 100 cycles.
- FIG. 15 is a diagram showing a discharge carp of graphite Q when the charge capacity in the first cycle is 1 OmAhZg.
- FIG. 16 is a diagram showing a discharge curve of graphite Q when the charge capacity in the first cycle is 2 OmAhZg.
- FIG. 17 is a diagram showing a discharge curve of graphite Q when the charge capacity in the first cycle is 5 OmAhZg.
- FIG. 18 is a diagram showing a discharge curve of graphite Q when the charge capacity in the first cycle is 6 OmAhZg.
- FIG. 19 is a diagram showing a discharge curve of graphite Q when the charge capacity in the first cycle is 8 OmAhZg.
- FIG. 20 is a diagram showing the charge / discharge cycle characteristics of the 18650 type cell.
- FIG. 21 is a diagram showing a discharge capacity retention ratio of the 18650 type cell.
- FIG. 22 is a view showing a discharge curve of the 18650 type battery. BEST MODE FOR CARRYING OUT THE INVENTION
- X-ray standard silicon powder 99.99%, manufactured by Flu Chemical Co., Ltd.
- a wide-angle X-ray is obtained by a reflection type diffractometer using the Cu-ray monochromated by a graph-it monochromator as the source. The diffraction curve was measured.
- the applied voltage and current to the X-ray tube are 4 OkV and 40 mA, the divergence slit is set to 2 °, the scatter slit is set to 2 °, and the receiving slit is set to 0.3 mm.
- the average particle size of the raw material coatas (including the carbon precursor) and the graphite powder obtained in the examples was measured using a laser diffraction type particle size distribution analyzer (Microtrac MT 300, manufactured by Nikkiso Co., Ltd.). did.
- the specific surface area A measured by the nitrogen adsorption (BET) method was measured using a BELS OR P288 manufactured by Japan Bell Co., Ltd., and dried under reduced pressure at 120 ° C for 3 hours. Measurement ⁇ Calculated.
- the surface area B obtained from the area average diameter was calculated by using a laser diffraction type particle size distribution analyzer (Microtrac MT300, manufactured by Nikkiso Co., Ltd.) to calculate the area average diameter D according to Equation 2.
- the intensity ratio of the intensity of the diffraction line corresponding to the (0 0 4) plane I (04) to the intensity I (0 6) of the diffraction line corresponding to the (0 06) plane I (0 4) / I (06) was measured using a powder X-ray wide-angle diffractometer using copper as the bulb.
- the sample holder is filled with graphite powder, the applied voltage and current to the X-ray tube are 40 kV and 40 mA, the separation slit is 1 °, the divergent slitker Sl °, and the light receiving slit is 0.
- Anthracene was placed in an autoclave, filled with 50 kg / cm 2 of nitrogen gas, and heated to 800 ° C. to carbonize. At this time, the heating rate is 100 ° CZ time from room temperature to 250 ° C, 50 ° CZ time from 250 ° C to 55 ° C, 55 ° C to 8 The time up to 00 ° C was defined as 100 ° CZ time. This The massive coatas thus obtained was once roughly pulverized by a stamp mill and then finely pulverized by a jet mill to obtain a carbon precursor powder having an average particle diameter of 24.3 ⁇ m. This powder was put into a graphite crucible, heated to 230 ° C at a rate of 300 ° C / hour in an argon gas atmosphere, kept for 1 hour, and allowed to cool to room temperature as it was .
- Graphite powder C was prepared according to the same procedure as for graphite A except that the final heat treatment temperature for graphite A was 260 ° C.
- Graphite powder D was prepared in the same procedure as for graphite B, except that the final heat treatment temperature of graphite B was set at 250 ° C.
- Graphite powder E was prepared according to the same procedure as for graphite A except that the final heat treatment temperature of graphite A was set at 280 ° C.
- Anthracene (Tokyo Kasei) and Penzaldehyde (Kanto Chemical) are mixed in a molar ratio of 1:15, and 6.0% by weight based on the mixture.
- paratoluenesulfonic acid monohydrate Kanto Chemical Co., Ltd.
- the condensable polycyclic polynuclear aromatic thus obtained was charged into a graphite crucible and placed in an electric furnace. Under a nitrogen atmosphere, the temperature was raised to 350 ° C. at a rate of 70 ° C./hour and held for 15 hours.
- the temperature was increased to 700 ° C at a rate of 70 ° C / hour, maintained for 1 hour, and allowed to cool to room temperature while maintaining a nitrogen gas flow.
- the massive carbon block obtained in this manner is put into a graphite crucible, heated to 2400 ° C at a heating rate of 300 ° C / hour in an argon gas atmosphere, held for 1 hour, and then left at room temperature. Allowed to cool to room temperature.
- the obtained graphite block was once roughly pulverized by a pin mill and then finely pulverized by a jet mill.
- Graphite powder G was produced according to the same procedure as for graphite F except that the final heat treatment temperature of graphite F was set at 280 ° C.
- the massive pitch coat obtained in the process of producing graphite B was once coarsely ground with a stamp mill and then finely ground with a jet mill to obtain a pitch coater powder having an average particle diameter of 50.0 ⁇ m.
- This powder was put into a graphite crucible, heated in an argon gas atmosphere to 230 ° C. at a rate of 300 ° C.Z for 1 hour, held for 1 hour, and then allowed to cool to room temperature.
- the massive pitch coke obtained during the production process of graphite B was once roughly pulverized by a stamp mill and then finely pulverized by a jet mill to obtain a pitch coke powder having an average particle diameter of 3.4 / im.
- This powder was put into a graphite crucible, heated to 230 ° C. in an argon gas atmosphere at a temperature rising rate of 300 ° C.Z for 1 hour, held for 1 hour, and then allowed to cool to room temperature.
- Graphite powder N with an average particle size of 6.6 ⁇ is charged into a graphite crucible in powder form, and heated up to 170 ° C at a rate of 300 ° C / hour in an argon gas atmosphere. The temperature was raised, maintained for 1 hour, and allowed to cool to room temperature.
- Graphite powder Q was prepared according to the same procedure as for graphite F, except that the final heat treatment temperature of graphite P was 260 ° C.
- Graphite powder Q was prepared according to the same procedure as for graphite F except that the final heat treatment temperature of graphite P was set at 280 ° C.
- Anthrone and polyphosphoric acid were mixed in a weight ratio of 7: 100 and heated at 140 ° C. for 24 hours. After standing to cool, distilled water was added, and the mixture was further stirred to decompose the remaining polyphosphoric acid into phosphoric acid. Then, ammonium bicarbonate was added to the black resin to neutralize the phosphoric acid. The remaining black mass resin is refluxed with methanol, and then further soxhlet extracted with methanol. Unreacted substances were extracted by the apparatus. The obtained black massive resin was heated up to 1200 ° C. at a heating rate of 50 ° C.Z for 1 hour, and then left to cool to room temperature to produce a massive carbon block.
- This block was once coarsely ground with a stamp mill and then finely ground with a jet mill to obtain carbon powder.
- This carbon powder was placed in an electric furnace, heated to 300 ° C. in a nitrogen stream, kept for 5 hours, and then allowed to cool to room temperature.
- Graphite powder Q was prepared according to the same procedure as for graphite F except that the final heat treatment temperature of graphite P was set at 300 ° C.
- Perylene and benzaldehyde were mixed at a molar ratio of 1: 2, 5% by weight of paratoluenesulfonic acid was added to the total weight of the mixture, and the mixture was heated at 150 ° C for 15 hours.
- the resulting black-green block resin was heated to 1200 ° C. at a rate of 50 ° C./hour, kept for 1 hour, and allowed to cool to room temperature to prepare a block carbon block.
- This block was once roughly pulverized with a stamp mill and then finely pulverized with a jet mill to obtain carbon powder.
- the carbon powder was placed in an electric furnace, heated to 300 ° C. in a nitrogen stream, kept for 5 hours, and then allowed to cool to room temperature.
- the massive pitch coat obtained during the production process of graphite B is put into a graphite crucible, and the temperature is raised to 280 ° C at a rate of 300 ° CZ in an argon gas atmosphere and maintained for 1 hour. Then, it was allowed to cool to room temperature.
- the obtained graphite block was coarsely ground with a pin mill and then finely ground with a jet mill.
- the massive process obtained during the graphite P production process is placed in a graphite crucible.
- the mixture was charged, and the temperature was raised to 280 ° C. in an argon gas atmosphere at a temperature rising rate of 300 ° C.Z for 1 hour.
- the obtained graphite block was coarsely ground with a pin mill and then finely ground with a jet mill.
- a 2% by weight aqueous solution of graphite powder (A to X) and CMC (carboxymethylcellulose) (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen 4H) was mixed at a weight ratio of 97: 3, and distilled water was mixed.
- a slurry was obtained.
- the ratio of CMC in the weight ratio is the ratio of solid content.
- the obtained slurry was applied to one side of an aluminum foil (thickness: 20 ⁇ ) by a doctor blade method so that the amount of graphite material per unit area was about 8.0 mg / cm 2, and was applied at 60 ° C. After drying for 0 minutes, a sheet electrode was prepared.
- the sheet was sandwiched between die sets, and the entire sheet was compressed and formed by a press machine so that the apparent density of the positive electrode mixture became about 0.90 g / cm 3 .
- the obtained sheet electrode was punched out with a punching press to 9 mm in diameter and used as the working electrode of the test cell.
- FIG. 1 shows a cross-sectional view of the test cell.
- the test cell 2 is a three-electrode type in which a working electrode 4 and a counter electrode 6 are pressurized by a spring 8 between a pair of upper and lower stainless steel fixing plates 20a and 20b.
- a sheet electrode 4a punched into 9 mm was used, and a lithium metal 6a was used for the upper counter electrode 6 and the reference electrode 10.
- the sheet electrode 4a is 120 ° C
- the bulk film 12 is 45 ° C
- the other resin parts and metal parts are 60 ° C, and dried under reduced pressure for 10 hours or more.
- Test cell 2 was assembled in an air atmosphere.
- a stainless block 22 made of polypropylene is interposed between the stainless fixing plates 20 and 20 and fastened and fixed with port nuts 24 and 26.
- the parafilm 12 is interposed between the stainless steel fixing plates 20 and 20 on the upper and lower surfaces of the inter-block 22.
- two nonwoven fabrics 14a made of polypropylene with a thickness of 100 ⁇ m are used and the reference electrode
- the lithium metal 10a which is 10 is inserted so as not to overlap with the counter electrode 6 and the working electrode 4.
- This reference electrode 10 is fixed to the long block 22 with fixing bolts 28.
- the sheet electrode 4a and the separator 14 were each placed in a Teflon container filled with an electrolytic solution, subjected to reduced pressure impregnation, and then incorporated into the test cell 2.
- the electrolyte used was a mixture of PC (propylene carbonate) and EMC (ethyl methyl carbonate) in a volume ratio of 1: 2 in a 2 (mo1 / L) concentration of LiPF. 6 is dissolved, and 100 parts by weight of vinylene carbonate is mixed with 0.5 part by weight of vinylene carbonate.
- an aluminum plate 30, a parafilm 12, and a polypropylene plate 32 are interposed from the upper side.
- a stainless disk 34 is mounted on the upper surface of the upper counter electrode 6, and a spring 8 is compression-inserted between the stainless disk 34 and the upper fixed plate 20b.
- a charge / discharge cycle was performed in a constant temperature room at 25 ° C in the atmosphere.
- the charge / discharge conditions for the first cycle are as follows: Set the current value so that the working electrode 4 has a current value of 20 mA Zg in terms of graphite weight, charge until it reaches 40 (mAh / g) in terms of graphite weight, After the pause, the discharge was performed at the same current until the potential of the working electrode 4 reached 3.0 (VV s L i + / L i) with respect to the reference electrode 10.
- the battery is charged at a constant current until the current becomes 4.70 (VV s L i + ZL i) .
- the battery is charged at 3.0 (VV s L i + ZL i) with the same current.
- the charge / discharge cycle for discharging until the end was reached was repeated 9 times.
- the above 10 cycles are preparation steps for performing normal charge and discharge, and are not included in the actual charge and discharge cycle.
- the next first cycle was designated as the first cycle (hereinafter referred to as “cycle initial”), and a normal charge / discharge cycle was performed in the following manner.
- cycle initial After charging for 4.65 (V vs L i + / L i) at a constant current of 300 (mA / g) in terms of graphite weight, and after a 1 minute pause, The charge / discharge cycle of discharging to 3.0 (V vs L i + / L i) at a constant current of 1 mA / cm 2 based on the applied area was repeated 100 times.
- the discharge capacity at the first cycle and the 100th cycle and the capacity retention ratio (the 100th cycle at the 100th cycle with respect to the discharge capacity at the first cycle) Table 1 shows the discharge capacity ratio.
- the charge capacity in the first cycle was 10, 15, 20, 40, 50, 55, 6 by the same operation at a constant current of the same current density.
- 0, 70, and 80 (mA h / g) were set, and the subsequent charge and discharge operations were performed in the same manner.
- FIG. 2 shows the structure of an 18650 type wound lithium secondary battery to which the present invention is applied.
- reference numeral 1 denotes a positive electrode plate.
- graphite weight per unit area skilled enough for coating step is 8. 0 g Z cm 2, was controlled to a mixture density of the sheet electrode becomes 0. 9 gZ cm 3 in the rolling process.
- Nippon Steel Chemical's LP C-U is sequentially pulverized with a pin mill and a jet mill to form a fine powder having an average particle size of 3.2 ⁇ m 95 parts by weight, and polyvinylidene fluoride resin (Kureha Chemical Co., Ltd.) 5 parts by weight of KF # 110) were kneaded, and N-methyl-12-pyrrolidinone as a solvent was added to obtain a slurry.
- the slurry was applied on both sides of a copper foil 5 having a thickness of 14 ( ⁇ m), dried, rolled, and cut into a width of 54 mm to prepare a strip-shaped negative electrode sheet. A part of this sheet was stripped of the mixture perpendicular to the longitudinal direction of the sheet, and a nickel-plated negative electrode lead plate 7 was attached to the current collector by spot welding.
- the carbon weight per unit area was controlled to be 1.0 mg / cm 2
- the mixture density of the sheet electrode was controlled to be 1.0 g Z cm 3 .
- the electrolyte used was a mixture of propylene carbonate (PC) and getyl carbonate (DEC) in a volume ratio of 1: 2, and a mixture of vinylene carbonate (VC) in various volume ratios.
- L i PF 6 is 2. was prepared by dissolving such that 0 (mo 1 / L). The solvent volume ratio is as shown in Table 2 below. Table 2 Volume ratio of solvent contained in the electrolyte used
- the cover element includes a metal positive electrode terminal plate 8, an intermediate pressure sensing plate 14, a conductive member (10, 11) including an upwardly projecting protrusion 10 and a base 11;
- the positive electrode terminal plate 8 and the fixing plate 12 are provided with a gas vent hole, and the conductive component (10, 11) is formed on the fixing plate 12
- the upper surface of the protrusion 10 is exposed on the upper surface, the lower surface of the base 11 is exposed on the lower surface of the fixing plate 12, and the gasket is formed on the inner periphery of the opening of the battery case 17.
- the conductive member (10, 11) and the intermediate pressure-sensitive plate 14 are connected to each other at the protruding portion 10 of the conductive member (10, 11), and include a connection part 15 thereof. Both are conducting only at the contact point,
- the tip of the positive electrode lead plate 18 is connected to the base 11 of the conductive material (10, 11), and the gasket is formed by caulking the opening of the battery case 17 inward. 13 is compressed, and the battery case 17 is hermetically sealed with the sandbag element. The inside of the battery case 17 reaches a predetermined internal pressure.
- connection portion 15 of the protruding portion 10 of the conductive member (10, 11) is broken by the intermediate terminal plate 14 bulging outward, whereby the positive electrode lead plate 1
- the configuration is such that the conductive path between the positive electrode terminal plate 8 and the positive electrode terminal plate 8 is cut off.
- Reference numeral 6 denotes a polypropylene insulating bottom plate, which has a hole so as to have the same area as the space A generated during winding.
- Reference numeral 16 denotes an insulating plate inserted so that the wound electrode group and the positive electrode lead plate are not short-circuited.
- the size of the completed battery is cylindrical (180 mm X 65 Omm).
- Table 1 shows the discharge capacity at the beginning of the cycle, the discharge capacity after the 100,000 cycles, and the after 100,000 cycles for all the graphite materials A to X tested. Shows the discharge capacity retention ratio of the sample. Note that the discharge capacity retention ratio is a value expressed by a ratio of 100% (%) of the discharge capacity after 100 cycles to the discharge capacity at the beginning of the cycle.
- FIG. 3 shows the relationship with the capacity retention rate after 100,000 cycles. It was observed that the discharge capacity at the beginning of the cycle tended to increase as L c (112) increased. The larger the crystallite, the more graphite This is probably because the crystal structure developed and the area where the adjacent hexagonal mesh planes were regularly arranged became larger, and the number of crystal sites at which the anion could reversibly interlock was increased. As typical examples, the discharge curves of graphite C, V, Q, L and R are shown in Figs.
- Graphites M and N are included in the scope of the first invention of the present application, that is, Lc (112) is included in the range of 4 nm or more and 30 nm or less, but from the viewpoint of the manufacturing method, graphite They are common in that they are pulverized after chemical treatment. In such a graphite material, mechanical energy due to the pulverization is accumulated, the surface irregularities of the particles are large, and the strain is introduced into the crystal structure, so that the anion intercalation reaction does not proceed smoothly. Is in a bad state. Fig.
- FIG. 11 shows the discharge curve of graphite O obtained by heat-treating graphite N at 1700 ° C. Even if it is graphite powder (graphite M, N) into which crystal distortion and particle surface irregularities have been introduced by pulverization after graphitization, the AZB value and strength can be obtained by heat-treating the powder again (graphite I). The ratio I (004) ZI (006) was found to decrease.
- the capacity retention rate after 100 cycles decreased extremely when L c (112) was less than 4 nm and when L c (30) exceeded 30 nm.
- the capacity retention rate was 80% or more when L c (111) was 4 nm or more and 30 nm or less as in the first invention of the present application.
- the crystallite is appropriately small, and it can be determined that the size is 30 nm.
- the capacity retention rate after 80 cycles was 80% or more because L c (1 1 2) was up to 30 nm, and this numerical range was used as the positive electrode. It is indispensable to improve the cycle characteristics of graphite materials.
- the graphite materials E, G, H, I, J, K, L, M, N, ⁇ , P, Q, V, W, and X where L c (1 1 2) was up to 30 nm Of the diffraction line intensity I (004) corresponding to the (004) plane with respect to the diffraction line intensity I (06) corresponding to the (06) plane obtained by the X-ray wide-angle diffraction method.
- FIG. 13 shows the relationship between the intensity ratio I (004) ZI (06) and the discharge capacity retention rate after 100 cycles.
- FIG. 14 shows the relationship between the charge capacity in the first cycle and the discharge capacity at the beginning of the cycle, and the relationship between the discharge capacity retention rate after 100 cycles.
- Table 3 shows the charge capacity of the first cycle, the discharge capacity obtained at the beginning of the cycle, the discharge capacity after 100 cycles, and the discharge capacity retention rate.
- Discharge curves 15 to 19 when the charge capacity is 10, 20, 50, 60, 80 mA h / g are shown.
- Fig. 6 shows the discharge curve at 40 mAh / g. From Fig. 14, it was confirmed that the smaller the charge capacity of the first cycle, the larger the discharge capacity obtained at the beginning of the cycle.
- the discharge capacity retention rate after 1000 cycles is the first Even if the charge capacity at the cycle was small or large, it decreased, and there was a maximum value near 40 mAhZg. If the charge capacity in the first cycle is small, a large charge / discharge capacity is obtained from the second cycle onward, and a large amount of the inter force enters and exits the graphite crystal, and the graphite crystal collapses. And cycle deterioration is likely to occur.
- the charge and discharge are performed in a state where a large amount of the residual compound is present in the graphite crystal, and the physical properties of the graphite powder (particularly, the particle surface) change.
- the reactivity with the electrolyte is increased, the particle surface is covered with the reaction product with the electrolyte, the resistance polarization is increased, and the cycle is deteriorated.
- the charge capacity in the first cycle depends on the subsequent charge / discharge characteristics. It is an important factor that influences, and unless it is properly specified, it is not possible to bring out the good positive electrode characteristics of graphite materials. Therefore, the effect of the invention according to the present application cannot be obtained unless the charging capacity in the first cycle is specified first.
- the charge capacity in the first cycle in order to maintain the discharge capacity retention rate after 1 000 cycles at 80 ° / 0 or more, the charge capacity in the first cycle must be set to 20 to 50 mA h / g. I understand. The inventors have confirmed that the same tendency can be obtained not only with the graphite Q but also with other graphite powders whose Lc (111) is 4 to 30 nm.
- the graphite material of the positive electrode satisfying the above satisfies both the discharge capacity of 20 mAh / g or more and the discharge capacity retention rate after 100 cycles of 90 (%) or more.
- the AZB value is 20 or less
- the graphite powder of the positive electrode has a strength ratio I (004) ZI (006) of 15 or less, so that the cycle characteristics can be improved. Can be further improved.
- Lc (111) is 4 nm or less, or 30 nm or more. In some cases, good cycle characteristics cannot be obtained.
- Graphites J and W are common in that pitch coaters obtained by heating coal tar pitch manufactured by Kansai Thermal Chemical Co., Ltd. to 1200 ° C are used as graphite raw material.
- Graphite w differs from graphitization after being graphitized after being graphitized. Although there was no significant difference in the discharge capacity at the beginning of the cycle, the discharge capacity retention rate after 100 cycles was 97.3% for graphite J, whereas it was 97.3% for graphite W. 83.0%.
- the A / B value and the intensity ratio I (004) / I (06) were both smaller for graphite J. It has been found that it is possible to reduce the undulation of the crystal and to reduce the distortion of the crystal lattice. A similar trend was observed by comparing graphites Q and X. Therefore, it was determined that the production method of performing graphitization and then graphitizing was an effective method for improving the cycle characteristics of the positive electrode graphite material.
- Graphite N is graphite powder obtained by graphitizing carbonized mesophase pitch and then pulverizing it.
- Graphite O was heat-treated at 170 ° C in an inert gas atmosphere. .
- the discharge capacity at the beginning of the cycle was 21.2 mA h / g for graphite N, and 28.5 mA hZg for graphite O. Since Lc (1 12) did not show a large difference between the two, the lattice distortion of crystallites was relaxed and the lattice defects were reduced by the heat treatment at 1700 ° C. It is thought that the crystal area that can perform occlusion and release increased, and the capacity increased.
- the values of A / B and intensity ratio I (004) / 1 (06) are smaller for graphite N. This confirms that the heat treatment at 170 ° C. reduced the undulations on the particle surface and reduced the distortion of the crystal lattice.
- the capacity retention after 100 cycles was 82.1% for graphite N and 92.1% for graphite O.
- the reason for the improved cycle characteristics is the same as the reason for the increased discharge capacity. It was found that even the graphite powder which was pulverized after graphitization was improved in both discharge capacity and cycle characteristics by heat treatment at a temperature of 170 ° C. thereafter. Further, by comparing graphite G and H, it was confirmed that the same effect can be obtained even at a heat treatment of 280 ° C. From the above results, it was determined that heat treatment of graphite powder at 170 ° C. or more in an inert gas atmosphere could improve the vital properties of the positive electrode.
- Figure 20 shows the change in capacity with respect to the number of cycles of a 1865-type nonaqueous electrolyte secondary battery using graphite material F as the positive electrode and pitch coatas as the negative electrode.
- the changes are shown in Figure 21.
- Figure 22 shows the discharge curves at the beginning of the cycle and after 500 cycles, taking as an example the case where the volume ratio of VC to the total volume of the solvent was 0.5%, which had the highest capacity retention rate. .
- the capacity retention rate is a numerical value indicating the discharge capacity after 50,000 cycles with respect to the discharge capacity at the beginning of the cycle as a percentage.
- Table 4 shows the capacity retention rates after 50,000 cycles read from FIG. 21 for each electrolyte.
- Table 4 Capacity maintenance rate after 500,000 cycles
- the capacity retention rate after 50,000 cycles is 85% or more, whereas the values of 0.005 and In the case of 20 ° / 0, the capacity retention rate is 85 ° / 0 . Was less than. If the volume ratio of VC was too large or too small, the cycle characteristics could not be improved.
- the initial discharge capacity can be increased, the capacity retention rate is high, and the cycle characteristics are excellent. It can be a secondary battery.
- Graphite powder for a positive electrode of a secondary battery can be manufactured.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2003272947A AU2003272947A1 (en) | 2002-10-11 | 2003-10-08 | Nonaqueous electrolyte secondary battery and process for producing positive electrode for use in nonaqueous electrolyte secondary battery |
JP2004542847A JP4516845B2 (ja) | 2002-10-11 | 2003-10-08 | 非水電解質二次電池、及びこの非水電解二次電池に用いる正極の製造方法 |
US11/103,420 US7452633B2 (en) | 2002-10-11 | 2005-04-11 | Non-aqueous electrolyte secondary battery and process for producing positive electrode for use in non-aqueous electrolyte secondary battery |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2002299238 | 2002-10-11 | ||
JP2002-299238 | 2002-10-11 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/103,420 Continuation US7452633B2 (en) | 2002-10-11 | 2005-04-11 | Non-aqueous electrolyte secondary battery and process for producing positive electrode for use in non-aqueous electrolyte secondary battery |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2004034491A1 true WO2004034491A1 (ja) | 2004-04-22 |
Family
ID=32089337
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2003/012906 WO2004034491A1 (ja) | 2002-10-11 | 2003-10-08 | 非水電解質二次電池、及びこの非水電解二次電池に用いる正極の製造方法 |
Country Status (4)
Country | Link |
---|---|
US (1) | US7452633B2 (ja) |
JP (1) | JP4516845B2 (ja) |
AU (1) | AU2003272947A1 (ja) |
WO (1) | WO2004034491A1 (ja) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007299698A (ja) * | 2006-05-02 | 2007-11-15 | Fdk Corp | リチウムイオン蓄電素子の製造方法 |
JP2007305522A (ja) * | 2006-05-15 | 2007-11-22 | Fdk Corp | 蓄電素子 |
JP2007305521A (ja) * | 2006-05-15 | 2007-11-22 | Fdk Corp | リチウムイオン蓄電素子 |
WO2008038551A1 (fr) * | 2006-09-28 | 2008-04-03 | Fdk Corporation | Accumulateur au lithium |
WO2008047898A1 (en) * | 2006-10-20 | 2008-04-24 | Ishihara Sangyo Kaisha, Ltd. | Storage device |
WO2011034152A1 (ja) * | 2009-09-18 | 2011-03-24 | Jx日鉱日石エネルギー株式会社 | リチウム二次電池の負極用炭素材料及びその製造方法 |
JP5269231B1 (ja) * | 2012-06-29 | 2013-08-21 | エム・ティー・カーボン株式会社 | リチウムイオン二次電池負極用の黒鉛材料、それを用いたリチウムイオン二次電池及びリチウムイオン二次電池用の黒鉛材料の製造方法 |
JP2013196978A (ja) * | 2012-03-21 | 2013-09-30 | National Institute Of Advanced Industrial & Technology | ナトリウム二次電池用正極材料及びその製造方法、並びにナトリウム二次電池用正極、ナトリウム二次電池及びこれを用いた電気機器 |
WO2014050097A1 (ja) * | 2012-09-27 | 2014-04-03 | 昭和電工株式会社 | リチウムイオン二次電池負極用炭素材およびその製造方法並びに用途 |
JP2014160629A (ja) * | 2013-02-20 | 2014-09-04 | Idemitsu Kosan Co Ltd | 負極材料 |
US9831521B2 (en) | 2012-12-28 | 2017-11-28 | Ricoh Company, Ltd. | Nonaqueous electrolytic storage element |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3920310B1 (ja) * | 2006-03-10 | 2007-05-30 | 株式会社パワーシステム | 電気二重層キャパシタ用正電極及び電気二重層キャパシタ |
JP5457101B2 (ja) * | 2009-08-05 | 2014-04-02 | パナソニック株式会社 | 非水電解質二次電池 |
JP5931727B2 (ja) * | 2010-08-11 | 2016-06-08 | Jxエネルギー株式会社 | リチウム二次電池負極用黒鉛材料およびその製造方法、およびそれを用いたリチウム二次電池 |
JP5612428B2 (ja) | 2010-10-08 | 2014-10-22 | Jx日鉱日石エネルギー株式会社 | 格子歪を有するリチウムイオン二次電池負極用黒鉛材料及びリチウムイオン二次電池 |
JP2014112524A (ja) | 2012-11-12 | 2014-06-19 | Ricoh Co Ltd | 非水電解液蓄電素子 |
CN116247202A (zh) | 2020-03-27 | 2023-06-09 | 宁德时代新能源科技股份有限公司 | 二次电池和包含二次电池的装置 |
CN111969185B (zh) * | 2020-07-07 | 2022-04-01 | 湖南大学 | 包覆TiO2的石墨双离子电池复合正极材料及其制备方法 |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS617567A (ja) * | 1984-06-22 | 1986-01-14 | Hitachi Ltd | 二次電池およびその製造法 |
JPS61111907A (ja) * | 1984-11-02 | 1986-05-30 | Mitsubishi Petrochem Co Ltd | 電極材 |
JPS63964A (ja) * | 1986-06-20 | 1988-01-05 | Mitsubishi Petrochem Co Ltd | 非水溶媒二次電池 |
JP2000353511A (ja) * | 1999-06-09 | 2000-12-19 | Fuji Elelctrochem Co Ltd | 非水電解液2次電池 |
JP2001351627A (ja) * | 2000-06-06 | 2001-12-21 | Fdk Corp | リチウムイオン二次電池 |
JP2003203674A (ja) * | 2001-10-29 | 2003-07-18 | Sanyo Electric Co Ltd | 非水電解質二次電池 |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2948097B2 (ja) * | 1994-04-28 | 1999-09-13 | 呉羽化学工業株式会社 | 二次電池電極用黒鉛質材料およびその製造法 |
-
2003
- 2003-10-08 JP JP2004542847A patent/JP4516845B2/ja not_active Expired - Fee Related
- 2003-10-08 AU AU2003272947A patent/AU2003272947A1/en not_active Abandoned
- 2003-10-08 WO PCT/JP2003/012906 patent/WO2004034491A1/ja active Application Filing
-
2005
- 2005-04-11 US US11/103,420 patent/US7452633B2/en not_active Expired - Fee Related
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS617567A (ja) * | 1984-06-22 | 1986-01-14 | Hitachi Ltd | 二次電池およびその製造法 |
JPS61111907A (ja) * | 1984-11-02 | 1986-05-30 | Mitsubishi Petrochem Co Ltd | 電極材 |
JPS63964A (ja) * | 1986-06-20 | 1988-01-05 | Mitsubishi Petrochem Co Ltd | 非水溶媒二次電池 |
JP2000353511A (ja) * | 1999-06-09 | 2000-12-19 | Fuji Elelctrochem Co Ltd | 非水電解液2次電池 |
JP2001351627A (ja) * | 2000-06-06 | 2001-12-21 | Fdk Corp | リチウムイオン二次電池 |
JP2003203674A (ja) * | 2001-10-29 | 2003-07-18 | Sanyo Electric Co Ltd | 非水電解質二次電池 |
Non-Patent Citations (1)
Title |
---|
TAKASHI SUZUKI ET AL.: "Hosoka Kokuen Zairyo no Seikyoku Tokusei to Denchi Tokusei", DAI 43 KAI BATTERY SYMPOSIUM IN JAPAN, vol. 2A10, 12 October 2002 (2002-10-12), pages 170 - 171, XP002977450 * |
Cited By (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007299698A (ja) * | 2006-05-02 | 2007-11-15 | Fdk Corp | リチウムイオン蓄電素子の製造方法 |
JP2007305522A (ja) * | 2006-05-15 | 2007-11-22 | Fdk Corp | 蓄電素子 |
JP2007305521A (ja) * | 2006-05-15 | 2007-11-22 | Fdk Corp | リチウムイオン蓄電素子 |
WO2008038551A1 (fr) * | 2006-09-28 | 2008-04-03 | Fdk Corporation | Accumulateur au lithium |
JP2008084772A (ja) * | 2006-09-28 | 2008-04-10 | Fdk Corp | リチウム二次電池 |
WO2008047898A1 (en) * | 2006-10-20 | 2008-04-24 | Ishihara Sangyo Kaisha, Ltd. | Storage device |
US8724293B2 (en) | 2006-10-20 | 2014-05-13 | Ishihara Sangyo Kaisha, Ltd. | Storage device |
CN102511096A (zh) * | 2009-09-18 | 2012-06-20 | 吉坤日矿日石能源株式会社 | 锂二次电池的负极用碳材料及其制造方法 |
JP2011065961A (ja) * | 2009-09-18 | 2011-03-31 | Jx Nippon Oil & Energy Corp | リチウム二次電池の負極用炭素材料及びその製造方法 |
US8617508B2 (en) | 2009-09-18 | 2013-12-31 | Jx Nippon Oil & Energy Corporation | Carbon material for negative electrode of lithium secondary battery and method for producing the same |
WO2011034152A1 (ja) * | 2009-09-18 | 2011-03-24 | Jx日鉱日石エネルギー株式会社 | リチウム二次電池の負極用炭素材料及びその製造方法 |
JP2013196978A (ja) * | 2012-03-21 | 2013-09-30 | National Institute Of Advanced Industrial & Technology | ナトリウム二次電池用正極材料及びその製造方法、並びにナトリウム二次電池用正極、ナトリウム二次電池及びこれを用いた電気機器 |
JP5269231B1 (ja) * | 2012-06-29 | 2013-08-21 | エム・ティー・カーボン株式会社 | リチウムイオン二次電池負極用の黒鉛材料、それを用いたリチウムイオン二次電池及びリチウムイオン二次電池用の黒鉛材料の製造方法 |
WO2014002477A1 (ja) * | 2012-06-29 | 2014-01-03 | エム・ティー・カーボン株式会社 | リチウムイオン二次電池負極用の黒鉛材料、それを用いたリチウムイオン二次電池及びリチウムイオン二次電池用の黒鉛材料の製造方法 |
US9831490B2 (en) | 2012-06-29 | 2017-11-28 | Mt Carbon Co., Ltd. | Graphite material for negative electrode of lithium-ion secondary battery, lithium-ion secondary battery including the graphite material, and method of manufacturing graphite material for lithium-ion secondary battery |
WO2014050097A1 (ja) * | 2012-09-27 | 2014-04-03 | 昭和電工株式会社 | リチウムイオン二次電池負極用炭素材およびその製造方法並びに用途 |
US9831521B2 (en) | 2012-12-28 | 2017-11-28 | Ricoh Company, Ltd. | Nonaqueous electrolytic storage element |
JP2014160629A (ja) * | 2013-02-20 | 2014-09-04 | Idemitsu Kosan Co Ltd | 負極材料 |
Also Published As
Publication number | Publication date |
---|---|
AU2003272947A1 (en) | 2004-05-04 |
JP4516845B2 (ja) | 2010-08-04 |
JPWO2004034491A1 (ja) | 2006-02-09 |
US20060292447A1 (en) | 2006-12-28 |
US7452633B2 (en) | 2008-11-18 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP4392169B2 (ja) | 非水電解質二次電池及びその正極材料の製造方法 | |
EP2894703B1 (en) | Nonaqueous electrolyte secondary battery | |
KR100342808B1 (ko) | 비수전해액2차전지 | |
JP4760379B2 (ja) | リチウム二次電池用負極及びリチウム二次電池 | |
US7452633B2 (en) | Non-aqueous electrolyte secondary battery and process for producing positive electrode for use in non-aqueous electrolyte secondary battery | |
WO1998005083A1 (fr) | Cellule electrolytique secondaire non aqueuse | |
EP1967493A1 (en) | Composite graphite particles and lithium rechargeable battery using the same | |
US20180019472A1 (en) | Method for manufacturing graphite powder for negative-electrode material for lithium-ion secondary battery, negative electrode for lithium-ion secondary battery, and lithium-ion secondary battery | |
JP4933092B2 (ja) | リチウムイオン二次電池用負極材料、リチウムイオン二次電池用負極およびリチウムイオン二次電池 | |
JP2004134658A (ja) | 充放電可能な電気化学素子 | |
JP4354723B2 (ja) | 黒鉛質粒子の製造方法 | |
JP4314087B2 (ja) | 非水電解質二次電池 | |
JP2001089118A (ja) | 黒鉛粒子、その製造法、リチウム二次電池用負極及びリチウム二次電池 | |
JP2002141062A (ja) | リチウム二次電池負極用黒鉛−炭素複合材料、その製造方法及びリチウム二次電池 | |
JP4232404B2 (ja) | リチウム二次電池用負極及びリチウム二次電池 | |
JP2630939B2 (ja) | 非水系二次電池 | |
JP2001148241A (ja) | 非水電解質電池 | |
JP6060996B2 (ja) | リチウム二次電池用負極及びリチウム二次電池 | |
JP4985611B2 (ja) | リチウム二次電池用負極及びリチウム二次電池 | |
JP2001185149A (ja) | リチウム二次電池 | |
JP6481714B2 (ja) | リチウム二次電池用負極及びリチウム二次電池 | |
JP5001977B2 (ja) | 黒鉛質粒子、リチウムイオン二次電池およびその負極材料 | |
JP2017033945A (ja) | リチウム二次電池用負極及びリチウム二次電池 | |
JPH10270080A (ja) | 非水電解液二次電池 | |
JP5776823B2 (ja) | リチウム二次電池用負極及びリチウム二次電池 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 11103420 Country of ref document: US Ref document number: 2004542847 Country of ref document: JP |
|
122 | Ep: pct application non-entry in european phase | ||
WWP | Wipo information: published in national office |
Ref document number: 11103420 Country of ref document: US |