CN1701459A - Secondary cell - Google Patents
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- CN1701459A CN1701459A CNA038127598A CN03812759A CN1701459A CN 1701459 A CN1701459 A CN 1701459A CN A038127598 A CNA038127598 A CN A038127598A CN 03812759 A CN03812759 A CN 03812759A CN 1701459 A CN1701459 A CN 1701459A
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0569—Liquid materials characterised by the solvents
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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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
- 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
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
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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
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
- H01M2300/0028—Organic electrolyte characterised by the solvent
- H01M2300/0037—Mixture of solvents
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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
- H01M4/48—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
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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
- H01M4/48—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
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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
- H01M4/58—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
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- 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
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- 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
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Abstract
A positive electrode active material having an average discharge potential of 4.5V or more to Li is used. A solvent of the electrolyte is a combination of a high-dielectric solvent such as ethylene carbonate and at least one of dimethyl carbonate or ethyl methyl carbonate. The decrease of the capacity due to cycle and the degradation of the reliability due to high temperature are prevented. The operating voltage is high.
Description
Technical Field
The present invention relates to a secondary battery, and more particularly to a secondary battery including a positive electrode active material having an average discharge potential of 4.5V or more with respect to Li metal.
Background
Lithium ion secondary batteries are widely used in portable electronic devices, personal computers, and the like. In addition, the present invention is expected to be applied to automobiles in the future. In these applications, although reduction in size and weight of the battery has been pursued, on the other hand, improvement in energy density of the battery is also an important technical problem.
There are several methods for increasing the energy density of a lithium ion secondary battery, but among them, increasing the operating potential of the battery is an effective means. The conventional method for preparing lithium cobaltate (LiCoO)2) Or lithium manganate (LiMn)2O4) In a lithium ion secondary battery used as a positive electrode active material, the operating potential of the lithium ion secondary battery reaches 4V class (average operating potential is 3.6 to 3.8V: relative to the lithium metal potential). This is because of the redox reaction of Co ions or Mn ions: ( Or ) To define the discovery potential. On the contrary, it is known that an operating potential of 5V class can be achieved by using, as an active material, a spinel compound in which Mn of lithium manganate is substituted with Ni or the like. Specifically, it is known to use LiNi0.5Mn1.5O4Iso-spinel compounds show a potential plateau in the region above 4.5V (j. electrochem. soc., vol.144, 204 (1997)). In this spinel compound, Mn exists in a state of 4 valence, substituted By oxidation-reduction of The oxidation-reduction of (2) defines an action potential.
However, in the reaction of LiNi0.5Mn1.5O4The positive electrode material of 5V class is used as active material in battery, and has LiCoO2、LiMn2O4In the case of a battery containing a 4V-class active material, the decomposition reaction of the electrolyte occurs due to a higher positive electrode potential, and when the battery is left in a charge-discharge cycle or in a charged state, a significant electrolyte occurs with a decrease in capacityThe problem of deterioration of. In addition, the phenomenon described above tends to be more pronounced during operation in a high-temperature environment such as 50 ℃.
In particular, in a battery using a 5V-grade spinel-type lithium manganese complex oxide for the positive electrode and amorphous carbon for the negative electrode, there is a problem of capacity reduction due to accumulation of decomposition products of the electrolyte solution on the surface of the negative electrode.
Disclosure of Invention
In view of the above circumstances, an object of the present invention is to provide a secondary battery that achieves a high operating voltage while suppressing a reduction in the capacity accompanying the cycle and a reduction in the reliability at high temperatures. The present invention achieves the object by improving the reduction in capacity generated in a battery using a 5V-grade spinel-type lithium manganese composite oxide in a positive electrode and amorphous carbon in a negative electrode.
The present invention provides a secondary battery comprising a positive electrode active material having an average discharge potential of 4.5V or more with respect to Li metal, and an electrolyte solution containing a high dielectric constant solvent (component a) and another solvent (component b) composed of at least one of dimethyl carbonate and ethyl methyl carbonate.
As described above, in the secondary battery having the positive electrode active material of 5V class, a high voltage is generated in the battery, and deterioration of the electrolytic solution becomes remarkable. As a result of intensive studies, the present inventors have found that when a solvent as described above is selected as a solvent constituting an electrolytic solution, an electrolytic solution having excellent durability and little deterioration even under high voltage conditions can be realized.
In the secondary battery of the present invention, since the decomposition reaction of the electrolytic solution is reduced, the absolute amount of the decomposition product of the electrolytic solution is small. Therefore, the accumulation of these decomposition products on the surface of the negative electrode, which is a cause of capacity reduction accompanying the cycle, can be suppressed.
Dimethyl carbonate or ethyl methyl carbonate produces a film on the surface of the negative electrode during initial charge and discharge, and has an effect of suppressing the precipitation of the decomposition product on the surface of the negative electrode. The term "high dielectric constant solvent" used in the present invention means a solvent having a dielectric constant of 40 or more, such as ethylene carbonate, propylene carbonate, butylene carbonate, and the like.
In Japanese unexamined patent application publication Nos. 2000-133263 and 2001-357848, batteries using a compound in which a part of Mn in spinel-type lithium manganate is substituted with another element such as Al as a positive electrode active material and a mixed solvent of ethylene carbonate and dimethyl carbonate as a solvent used in an electrolyte solution are disclosed. However, these are batteries using a 4V-class positive electrode active material, and are fundamentally different from the present invention using a 5V-class positive electrode active material. This point will be explained below.
The compounds described in the above-mentioned publications, in which a part of the 4V spinel lithium manganate and Mn is substituted with another element such as Al, are utilized So that Mn must be contained3+。
The Mn is3+Mn is produced by the reaction of the following formula2+。
Due to Mn thus produced2+Therefore, when the positive electrode active material is used, it is an important problem to suppress elution of Mn.
In addition, in the presence of Mn3+In the 4V-class positive electrode active material of (1), when the average valence of Mn ions varies between 3-valence and 4-valence, a problem occurs in that a young-teller distortion occurs in a crystal, stability of a crystal structure is lowered, and capacity deterioration occurs with a cycle.
In order to solve such problems, the above-mentioned publication adopts a measure of adjusting the composition of the positive electrode active material or adjusting the production conditions of the active material layer.
On the other hand, in the present invention using the 5V-class positive electrode active material, spinels at the 4V classThe elution of Mn generated in lithium manganate or the likeand the decrease in stability of the crystal structure do not become problems, but the decomposition of the electrolyte generated when a high electric field is applied becomes a problem. In a battery using a 5V-class positive electrode active material, an electrolyte solution containing a lithium salt of an alkali metal compound and an electrolyte More predominantly as a higher potential than the redox potential of 、 And the like. Therefore, most of Mn in these positive electrode active materials is Mn4+In the form of (B), Mn3+Usually in trace amounts. Therefore, in the present invention, elution of Mn generated in 4V-grade spinel-type lithium manganate or the like and reduction in stability of crystal structure do not become problems, and it becomes an important technical subject to prevent deterioration of the electrolytic solution due to a mechanism different from that.
The present invention is to solve such problems and to suppress deterioration of an electrolyte solution caused by a high voltage in a battery. In addition, when the interaction between the positive electrode active material and the electrolyte is developed by the selection of the positive electrode active material and the negative electrode active material, and the electrolyte is significantly deteriorated, the present invention can effectively suppress the deterioration of the electrolyte. That is, the present invention solves the problems specific to the case of using a 5V-class positive electrode active material, and provides a battery having a long life while achieving a high battery voltage.
The secondary battery may also have a configuration further including a negative electrode active material containing amorphous carbon.
When amorphous carbon is used as the negative electrode active material, the deposition of the decomposition product on the surface of the negative electrode is further reduced, and therefore, the cycle characteristics are further improved.
In a preferred embodiment of the secondary battery of the present invention, a volume ratio of the component a to the electrolyte is in a range of 10 to 70%.
Here, the component b is preferably a solvent having a low dielectric constant, contrary to the component a. Examples thereof include a polycarbonate containing dimethyl carbonate: 3.1, methyl ethyl carbonate: 2.9 of a mixture. Generally, a high dielectric constant solvent has a high viscosity, and a low dielectric constant solvent has a low viscosity. In the present invention, by setting the volume ratio of the component a as described above, the dielectric constant and viscosity of the entire electrolyte solution are appropriately maintained. In this way, the deposition of the decomposition product on the surface of the negative electrode can be further suppressed while the conductivity of the electrolyte solution is ensured.
In the secondary battery, the high dielectric constant solvent may be ethylene carbonate or propylene carbonate. By selecting the solvent as described above as the high dielectric constant solvent, a secondary battery having good cycle characteristics can be realized.
In the secondary battery, the positive electrode active material may be a spinel-type lithium manganese composite oxide. With this configuration, a high-capacity secondary battery with a stable operating voltage can be obtained.
In the secondary battery, the spinel-type lithium manganese composite oxide may be represented by the following general formula (I):
Lia(NixMn2-x-yMy)(O4-wZw) (I)
(wherein x is 0.4-0.6, y is 0-0, Z is 0-2, x + y is 0-1, a is 0-1.2. M is at least one member selected from the group consisting of Li, Al, Mg, Ti, Si and Ge, and Z is at least one member selected from the group consisting of F and Cl.)
The spinel-type lithium manganese complex oxide is shown. The spinel-type lithium manganese complex oxide has a charge/discharge region in the range of 4.5V to 4.8V with respect to Li metal, and a discharge capacity of 4.5V or more reaches a very high capacity of 110 mAh/g.
According to the studies of the present inventors, deterioration of the electrolyte of a battery using the spinel-type lithium manganese complex oxide represented by the above general formula (I) as a positive electrode active material is considerably deteriorated to a degree exceeding that of deterioration due to high voltage. This is because some undesirable interaction occurs between the positive electrode active material and the electrolyte.
The present inventors have further studied and found that when an electrolyte solution containing at least one of a spinel-type lithium manganese complex oxide represented by formula (I) and dimethyl carbonate or ethyl methyl carbonate is used, deterioration of the electrolyte solution can be effectively suppressed by utilizing the synergistic effect of the spinel-type lithium manganese complex oxide represented by formula (I) and the electrolyte solution.
Therefore, the secondary battery of the present invention can maintain the excellent performance of the spinel-type lithium manganese complex oxide represented by the general formula (I) for a long period of time even after a plurality of cycles.
In the secondary battery, y in the general formula (I) may satisfy a relationship of 0<y. In the secondary battery, w in the general formula (I) may satisfy a relationship of 0<w.ltoreq.1. By reacting LiNi withxMn2-xO4In the above compounds, a part of Mn or O is substituted with another element to stabilize the crystal structure of the compound. Therefore, the decomposition reaction of the electrolytic solution can be reduced, and therefore, the cycle characteristics can be improved for the same reason as described above.
From the viewpoint of ensuring sufficient capacity, it is preferable that y in the general formula (I) satisfies the relationship of 0<y<0.3.
Drawings
Fig. 1 is a sectional view of a secondary battery according to an embodiment of the present invention.
Detailed Description
The secondary battery of the present invention includes a positive electrode containing a lithium-containing metal composite oxide as a positive electrode active material, and a negative electrode having a negative electrode active material capable of occluding and releasing lithium. Between the positive electrode and the negative electrode, a separator that does not bring them into electrical contact is interposed. The positive electrode and the negative electrode are immersed in an electrolyte having lithium ion conductivity, and are sealed in a battery case.
In the secondary battery of the present invention, a lithium metal is usedA positive electrode active material having an average discharge potential of 4.5V or more. For example, a composite oxide containing lithium is preferably used. The lithium-containing composite oxide may be exemplified by LiMn1-xMxO4Spinel-type lithium manganese complex oxide represented by (M ═ Ni, Co, Cr, Cu, Fe), and LiMPO4Olivine-type lithium-containing composite oxide represented by (M ═ Co, Ni, and Fe), and LiNiVO4And an isoinverse spinel type lithium-containing composite oxide.
Among the positive electrode active materials, LiNi, which is a spinel-type lithium manganese complex oxide capable of obtaining a high capacity of 130mAh/g or more and having a stable crystal structure, is preferably usedxMn2-xO4. The composition ratio x of Ni in the active material is in the range of 0.4-0.6. By such an arrangement, a discharge region of 4.5V or more can be sufficiently secured, and the energy density can be improved.
In addition, as the positive electrode active material, LiNi was usedxMn2-xO4In the case of a material in which a part of Mn in the alloy is substituted with Li, Al, Mg, Ti, Si or Ge, the cycle characteristics are further improved. This is because the crystal structure of the active material is further stabilized by substituting a part of Mn with the element described above. Therefore, decomposition of the electrolytic solution is suppressed, and the amount of decomposition products of the electrolytic solution is reduced. Therefore, it is estimated that the deposition of the decomposition product of the electrolyte solution on the negative electrode is reduced.
In addition, in the active material in which a part of O in the active material is replaced with F, Cl, or the like, a crystal structure is further stabilized, and thus, more favorable cycle characteristics are realized. In addition, in a system in which a part of Mn is substituted with an element having a valence of 1 to 3 such as Li, Al, or Mg, the capacity decreases as the substitution amount increases with an increase in the number of Ni valences. Substitution of O with a halogen such as F, Cl also has the advantage of being able to maintain a high capacity at the same time by offsetting this increase in the Ni valence.
In the secondary battery of the present invention, amorphous carbon is used as the negative electrode active material because, when amorphous carbon is used, accumulation of decomposition products of the electrolyte solution on the surface of the negative electrode is reduced and cycle characteristics are improved as compared with the case of using another material such as Li metal or natural graphite, and here, amorphous carbon means a carbon material having a broad scattering band having an apex at 15 to 40 degrees in the 2 θ value by X-ray diffraction method using the CuK α line.
In the secondary battery of the present invention, a solvent in which a high dielectric constant solvent and a low dielectric constant solvent are combined is used, and dimethyl carbonate (DMC) or Ethyl Methyl Carbonate (EMC) is used as the low dielectric constant solvent. By selecting such a solvent, decomposition is hardly caused even under a high voltage condition, and an electrolytic solution having excellent durability can be obtained. Therefore, since the amount of decomposition products of the electrolytic solution can be reduced, the deposition of these decomposition products on the surface of the negative electrode can be significantly suppressed. This can further reduce the capacity reduction accompanying the cycle. It is presumed that when dimethyl carbonate or ethyl methyl carbonate is used, a film containing a phosphate or a fluoride is formed on the surface of the negative electrode during initial charge and discharge, and the deposition of decomposition products generated on the positive electrode side on the surface of the negative electrode is suppressed.
When the 5V-spinel-type lithium manganese complex oxide represented by the general formula (I) is selected as the positive electrode active material and amorphous carbon is selected as the negative electrode active material, a secondary battery having excellent cycle characteristics can be obtained from the following (I) and (ii).
(i) When the 5V-grade spinel-type lithium manganese complex oxide represented by the general formula (I) is used as the positive electrode active material and an electrolyte containing DMC or EMC is used, the absolute amount of the electrolyte decomposition reactant can be significantly reduced because a synergistic effect of these active materials and DMC or EMC is produced.
(ii) By utilizing the synergistic effect of amorphous carbon and DMC or EMC, deposition on the surface of the negative electrode using amorphous carbon can be effectively suppressed even for an electrolyte decomposition reactant having a small absolute amount.
In addition, in the case of a secondary battery using a 4V-class positive electrode active material, when an electrolyte solution containing DMC or EMC was used, the above-described effects were not produced, and no significant improvement in cycle characteristics was observed. In a secondary battery using a 4V-class positive electrode active material, the voltage is low, and therefore decomposition of the electrolyte solution to such an extent that the decomposition affects the cycle characteristics does not occur. Therefore, in the secondary battery using the positive electrode active material of 4V class, when the electrolyte containing DMC or EMC is used, and when the electrolyte containing another low dielectric constant solvent such as DEC is used, no significant difference in cycle characteristics is generated.
On the other hand, as the high dielectric constant solvent, Ethylene Carbonate (EC), Propylene Carbonate (PC), Butylene Carbonate (BC), γ -butyrolactone (GBL), or the like can beused.
In addition, from the viewpoint of ensuring conductivity, the volume ratio of the high dielectric constant solvent to the low dielectric constant solvent is preferably in the range of 10: 90 to 70: 30. This is because, by adopting such a range, the dielectric constant and viscosity of the entire electrolyte can be appropriately set, and sufficient conductivity can be ensured.
In addition, the volume ratio of the high dielectric constant solvent to the low dielectric constant solvent is preferably in the range of 20: 80 to 60: 40, more preferably in the range of 30: 70 to 50: 50, from the viewpoint of reducing the deposition of the decomposition product of the electrolyte solution on the surface of the negative electrode. This is because, by providing such an arrangement, the effect of preventing adsorption of the decomposition product of the electrolytic solution to the surface of the negative electrode can be enhanced, and the decomposition reaction of the electrolytic solution can be suppressed.
Next, the operation of the lithium ion secondary battery of the present invention will be described. By applying a voltage to the positive electrode and the negative electrode, lithium ions are released from the positive electrode active material, and the lithium ions are occluded and stored by the negative electrode active material to form a charged state. On the other hand, when the positive electrode and the negative electrode are brought into electrical contact with each other outside the battery, lithium ions are released from the negative electrode active material, and the lithium ions are absorbed and stored by the positive electrode active material, causing discharge, contrary to the case of charging.
Next, a method for producing the positive electrode active material will be described.
When spinel type lithium manganese complex oxygen isusedWhen the compound is used as a positive electrode active material, the compound is used as a positive electrode active materialThe material for producing the substance may be Li, which is a raw material for Li2CO3、LiOH、Li2O、Li2SO4Etc., but Li is preferable2CO3LiOH, etc. As the Mn raw material, Electrolytic Manganese Dioxide (EMD). Mn can be used2O3、Mn3O4Various Mn oxides such as chemically synthesized manganese dioxide (CMD), MnCO3、MnSO4And the like. NiO and Ni (OH) can be used as the Ni material2、NiSO4、Ni(NO3)2And the like. As the raw material of the substitution element, an oxide, a carbonate, a hydroxide, a sulfide, a nitrate, or the like of the substitution element can be used. The Ni material, Mn material, and substitution element material may be difficult to diffuse elements during firing, and after firing the materials, Ni oxide, Mn oxide, and substitution element oxide may remain as heterogeneous phases. Therefore, after the Ni material, the Mn material, and the substitution element material are dissolved and mixed in an aqueous solution, a mixture of Ni and Mn precipitated as a hydroxide, a sulfate, a carbonate, a nitrate, or the like, or a mixture of Ni and Mn containing a substitution element can be used as the material. Further, an oxide of Ni or Mn or a mixed oxide of Ni, Mn or a substitution element obtained by firing the above mixture may be used. When such a mixture is used as a raw material, Mn, Ni, and a substitution element are well diffused at an atomic level, and Ni or the substitution element is easily introduced into a 16d site of a spinel structure. As a halogen material of the positive electrode active material, a halide such as LiF or LiCl can be used.
These raw materials are weighed and mixed in such a manner that the compositionratio of the metals is the desired one. The mixing is performed by pulverizing and mixing with a ball mill or the like. The positive electrode active material is obtained by firing the mixed powder at a temperature of from 600 ℃ to 1000 ℃ in air or oxygen. Although the firing temperature is preferably higher for diffusing the respective elements, if the firing temperature is too high, oxygen defects are generated, which adversely affects the battery characteristics. In this case, it is preferable to be from about 500 ℃ to about 800 ℃ in the final firing process.
In the case where an olivine-type lithium-containing composite oxide or an inverse spinel-type lithium-containing composite oxide is used as the positive electrode active material, the positive electrode active material can be obtained by mixing and diffusing the necessary elements in the same manner as described above and then firing the mixture.
The specific surface area of the obtained lithium metal composite oxide is preferably 3m, for example2A ratio of 1m or less per gram, preferably2The ratio of the carbon atoms to the carbon atoms is less than g. This is because, the larger the specific surface area is, the more the binder is required, which is disadvantageous in terms of the capacity density of the positive electrode.
The obtained positive electrode active material is mixed with a conductivity-imparting agent and formed on a current collector with a binder. As examples of the conductivity-imparting agent, in addition to the carbon material, a metal substance such as Al, a powder of a conductive oxide, and the like can be used. Polyvinylidene fluoride (PVDF) or the like can be used as the binder. As the current collector, a thin metal film mainly made of Al or the like can be used.
The addition amount of the conductivity-imparting agent is preferablyabout 1 to 10% by weight, and the addition amount of the binder is also about 1 to 10% by weight. This is because the larger the proportion by weight of the active material, the larger the capacity per unit weight. When the ratio of the conductivity-imparting agent to the binder is too small, the conductivity cannot be maintained or the electrode may be peeled off.
As described above, the solvent used in the electrolyte solution of the present invention may be a cyclic carbonate such as Vinylene Carbonate (VC), a linear carbonate such as diethyl carbonate (DEC) or dipropyl carbonate (DPC), an aliphatic carboxylic acid ester such as methyl formate, methyl acetate or ethyl propionate, a γ -lactone such as γ -butyrolactone, a linear ether such as 1, 2-ethoxyethane (DEE) or ethoxymethoxyethane (EME), a cyclic ether such as tetrahydrofuran or 2-methyltetrahydrofuran, dimethyl sulfoxide, 1, 3-dioxolane, formamide, acetamide, dimethylformamide, dioxolane, acetonitrile, propionitrile, nitromethane, ethylmonoglyme (ethylmonoglyme), phosphotriester, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, dimethylsulfolane, or the like, One or a mixture of two or more kinds of aprotic organic solvents such as 1, 3-dimethyl-2-imidazolidinone, 3-methyl-2-oxazolinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, 1, 3-propane sultone, anisoyl, N-methylpyrrolidone, and fluorinated carboxylic acid ester.
Lithium salts are dissolved in these organic solvents. The lithium salt includes, for example, LiPF6、LiAsF6、LiAlCl4、LiClO4、LiBF4、LiSbF6、LiCF3SO3、LiC4F9CO3、LiC(CF3SO2)2、LiN(CF3SO2)2、LiN(C2F5SO2)2、LiB10Cl10Lower aliphatic carboxylic acid lithium, chloroboron lithium, tetraphenylboronic acid lithium, LiBr, LiI, LiSCN, LiCl, imides, etc.
Instead of the electrolytic solution, a polymer electrolyte may be used. The electrolyte concentration is set, for example, from 0.5mol/l to 1.5 mol/l. When the concentration is too high, the density and viscosity increase. When the concentration is too low, the conductivity decreases.
As the negative electrode active material, various carbon materials such as natural graphite and artificial graphite can be used as a main component, but among them, amorphous carbon is preferably used as a main component. With this configuration, the accumulation of decomposition products of the electrolyte solution on the surface of the negative electrode can be reduced, and the cycle characteristics can be improved.
In addition, the negative electrode active material may contain a material capable of occluding and releasing lithium as a sub-component. As the material capable of occluding and releasing lithium, a carbon material, Li metal, Si, Sn, Al, SiO, SnO, or the like may be mixed and used.
The negative electrode active material is formed on the current collector by the conductivity-imparting agent and the binder. As an example of the conductivity-imparting agent, a powder of a conductive oxide or the like may be used in addition to the carbon material. Polyvinylidene fluoride or the like can be used as the binder. As the current collector, a metal thin film mainly composed of Cu or the like can be used.
The lithium secondary battery of the present invention can be produced by laminating a negative electrode and a positive electrode with a separator interposed therebetween or winding the laminated material in dry air or an inert gas atmosphere, and then storing the resultant in a battery can or sealing the battery with a flexible film or the like formed of a laminate of a synthetic resin and a metal foil.
Fig. 1 shows a coin-type battery as an example of the battery. The shape of the battery of the present invention is not limited, and the positive electrode and the negative electrode facing each other with a separator interposed therebetween may be in a wound form, a laminated form, or the like, or a coin-type, a laminate pack, a rectangular battery, or a cylindrical battery may be used as the battery.
Examples
The present invention will be described in detail below by showing examples. In this example, a coin-type battery as shown in fig. 1 is shown.
The 22 batteries shown in tables 1 to 4 were produced in the following procedure.
(preparation of Positive electrode) As sources of Mn, Ni, Li, Ti, Si, Al and F, MnO was added to each of the above2、NiO、Li2CO3、TiO2、SiO2、Al2O3And LiF are weighed according to the metal composition ratio to achieve the purpose, and are crushed and mixed. Further, LiF also serves as a source of Li. Then, the mixed powder of the raw materials was fired at 750 ℃ for 8 hours. All the crystal structures thus obtained were confirmed to have a substantially single-phase spinel structure. As shown in table 1, all of the active materials prepared were materials having an average discharge potential of 4.5V or more with respect to Li metal.
The prepared positive electrode active material and carbon as a conductivity-imparting agent were mixed and dispersed in N-methylpyrrolidone in which polyvinylidene fluoride (PVDF) as a binder was dissolved to form a slurry. The weight ratio of the positive electrode active material, the conductivity-imparting agent and the binder was 88: 6. The slurry was applied to an Al current collector. Thereafter, the resultant was dried in vacuum for 12 hours to obtain an electrode material. The electrode material was cut into a circle of 12mm in diameter. Thereafter, at 3t/cm2Is subjected to pressure forming to obtainA positive electrode current collector 3 and a positive electrode active material layer 1.
In the case of a battery using Li metal as a negative electrode active material, a lithium metal disk was placed on a Cu current collector, and a circle having a diameter of 13mm was cut out to obtain a negative electrode current collector 4 and a negative electrode active material layer 2.
In the case of a battery using natural graphite as a negative electrode active material, natural graphite is usedThe ink and carbon as a conductivity-imparting agent were mixed and dispersed in a solution in which polyvinylidene fluoride (PVDF) was dissolved in N-methylpyrrolidone to form a slurry. The weight ratio of the natural graphite, the conductivity-imparting agent and the binder was 91: 1: 8. The slurry was applied to a Cu current collector. Thereafter, the resultant was dried in vacuum for 12 hours to obtain an electrode material. The electrode material was cut into a circle of 13mm in diameter. Thereafter, at 1t/cm2The negative electrode current collector 4 and the negative electrode active material layer 2 were obtained by pressure molding.
In the case of a battery using amorphous carbon as a negative electrode active material, the battery was produced in the same manner as the battery using natural graphite. Further, カ - ボトロン (registered trademark) P manufactured by wuhui chemical corporation was used as the amorphous carbon.
A film of polypropylene is used for the separator 5. The positive electrode and the negative electrode were placed so as to face each other with a separator interposed therebetween in a non-electrical contact state, covered with a positive electrode outer packaging can 6 and a negative electrode outer packaging can 7 as shown in fig. 1, filled with an electrolyte solution having the composition and ratio (volume ratio) shown in table 1, and sealed with an insulating gasket 8.
LiPF is used as an electrolyte supporting salt6The concentration was set at 1 mol/L.
The batteries 1 to 16 produced as described above were evaluated for their cycle characteristics. At the time of the evaluation, the charge was charged to 4.8V with a charge rate of 1C, and the discharge was discharged to 2.5V with a rate of 1C. Here, "charging at a charging rate of 1C" means charging in which a number obtained when the capacity of the battery is represented by ampere hour is adopted as the current value of the charging current, and thus 1/10 representing the number is represented by, for example, 0.1C. The experimental temperature was set to 45 ℃. The results are shown in Table 1.
TABLE 1
| Battery with a battery cell | Positive electrode active material | Of positive electrode active material Relative to Li metal Average discharge potential | Solvent composition and volume ratio | Negative electrode active material | Capacity retention rate | |
| At 45 ℃ for 100 timesAfter circulation | After 300 cycles at 45 DEG C | |||||
| 1 | LiNi0.5Mn1.5O4 | 4.66V | EC/DEC＝40/60 | Li metal | 10％ | |
| 2 | LiNi0.5Mn1.5O4 | 4.66V | EC/DEC＝40/60 | Natural graphite | 40％ | 30％ |
| 3 | LiNi0.5Mn1.5O4 | 4.66V | EC/DEC＝40/60 | Natural graphite | 55％ | 40％ |
| 4 | LiNi0.5Mn1.5O4 | 4.66V | EC/DEC＝40/60 | Amorphous carbon | 60％ | 36％ |
| 5 | LiNi0.5Mn1.5O4 | 4.66V | EC/DEC＝40/60 | Amorphous carbon | 55％ | 40％ |
| 6 | LiNi0.5Mn1.5O4 | 4.66V | PC/EMC＝40/60 | Amorphous carbon | 65％ | 45％ |
| 7 | LiNi0.5Mn1.5O4 | 4.66V | EC/EMC＝40/60 | Amorphous carbon | 75％ | 47％ |
| 8 | LiNi0.5Mn1.5O4 | 4.66V | PC/DMC＝40/60 | Is notCrystalline carbon | 70％ | 56％ |
| 9 | LiNi0.5Mn1.5O4 | 4.66V | EC/DMC＝40/60 | Amorphous carbon | 80％ | 62％ |
| 10 | LiNi0.5Mn1.4Al0.1O4 | 4.65V | EC/DMC＝40/60 | Amorphous carbon | 84％ | 64％ |
| 11 | LiNi0.5Mn1.4Al0.1O3.9F0.1 | 4.65V | EC/DMC＝40/60 | Amorphous carbon | 85％ | 65％ |
| 12 | LiNi0.5Mn1.45Li0.05O4 | 4.65V | EC/DMC＝40/60 | Amorphous carbon | 82％ | 64％ |
| 13 | LiNi0.5Mn1.45Li0.05O3.85F0.15 | 4.65V | EC/DMC＝40/60 | Amorphous carbon | 84％ | 64％ |
| 14 | LiNi0.5Mn1.45Si0.05O4 | 4.65V | EC/DMC＝40/60 | Amorphous carbon | 84％ | 65％ |
| 15 | LiNi0.5Mn1.35Ti0.15O4 | 4.68V | EC/DMC＝40/60 | Amorphous carbon | 88％ | 70％ |
| 16 | LiNi0.5Mn1.45Ge0.05O4 | 4.64V | EC/DMC＝40/60 | Amorphous carbon | 87％ | 68％ |
(study of negative electrode active Material)
As a result of comparing batteries 1, 2, and 4 in table 1, it was found that the cycle reliability was higher when amorphous carbon was used as the negative electrode than when Li metal or natural graphite was used. Further, as can be seen from comparison of the batteries 3 and 9, in the case of the battery using EC/DMC as the electrolyte solution, the battery using amorphous carbon has more excellent cycle characteristics than the battery using natural graphite. From the above, in a battery using a 5V-class positive electrode active material, amorphous carbon is preferably used as the negative electrode. This is because when amorphous carbon is used as the negative electrode, the deposition of decomposition products of the electrolyte solution on the surface of the negative electrode is smaller than when other materials are used.
(investigation of solvent)
Next, LiNi will be used by comparison0.5Mn1.5O4The effect of the solvent was examined for batteries 4 to 9 using amorphous carbon as the positive electrode active material and the negative electrode active material.
In general, as a solvent constituting the electrolyte solution, a combined solvent of a high-viscosity high-dielectric-constant electrolyte solution and a low-viscosity low-dielectric-constant solvent is used. In the present example, EC or PC was used as a high-viscosity high-dielectric-constant solvent, and DEC, EMC or DMC was used as a low-viscosity low-dielectric-constant solvent.
Here, a solvent having a low viscosity and a low dielectric constant was fixed and studied. That is, when comparing batteries 4 and 5 (fixed to DEC), batteries 6 and 7 (fixed to EMC), or batteries 8 and 9 (fixed to DMC), it was confirmed that the cycle characteristics tend to be better when EC is used than when PC is used as a solvent having high viscosity and high dielectric constant, but no significant difference occurs.
Then, the solvent having high viscosity and high dielectric constant was fixed to EC or PC for investigation. When batteries 4, 7, and 9 were compared (fixed as EC), batteries 7 and 9 using EMC or DMC showed excellent cycle characteristics with a capacity retention rate of 75% or more after 100 cycles, and showed more excellent cycle characteristics than battery 4 using DEC. The same tendency was observed in comparison of the batteries 5, 6 and 8 (fixed to PC), and the batteries 6 and 8 using EMC or DMC exhibited more excellent cycle characteristics than the battery 5 using DEC.
From the above, EMC or DMC is preferably used as a solvent having a low viscosity and a low dielectric constant.
Here, it was investigated whether the significant effect as described above is exhibited when EMC or DMC is used as a low-viscosity, low-dielectric-constant solvent in a battery having a 4V-class positive electrode active material.
Table 2 shows the use of LiMn as a 4V grade positive electrode active material2O4Or LiNi as a 5V-class positive electrode active material0.5Mn1.35Ti0.15O4The cycle characteristics of the batteries 17 to 19 and the batteries 15, 20, and 21 using solvents having low viscosity and low dielectric constant, respectively, are shown in the table.
TABLE 2
| Battery with a battery cell | Positive electrode active material | Relative to positive electrode active material Average discharge potential of Li metal | Solvent composition and volume ratio | Negative electrode active material | Capacity retention rate | |
| After 300 cycles at 45 DEG C | After 500 cycles at 45 DEG C | |||||
| 17 | LiMn2O4 | 4.03V | PC/DEC＝40/60 | Amorphous carbon | -- | 78％ |
| 18 | LiMn2O4 | 4.03V | PC/EMC＝40/60 | Amorphous carbon | -- | 80％ |
| 19 | LiMn2O4 | 4.03V | PC/DMC＝40/60 | Amorphous carbon | -- | 84％ |
| 20 | LiNi0.5Mn1.35Ti0.15O4 | 4.68V | EC/DEC＝40/60 | Amorphous carbon | 40％ | ＜10％ |
| 21 | LiNi0.5Mn1.35Ti0.15O4 | 4.68V | EC/EMC＝40/60 | Amorphous carbon | 47％ | 20％ |
| 15 | LiNi0.5Mn1.35Ti0.15O4 | 4.68V | EC/DMC＝40/60 | Amorphous carbon | 74％ | 53％ |
In table 2, when the capacity retention after 500 cycles of the batteries 17 to 19 having the 4V-class positive electrode active material was compared, it was found that the batteries 18 and 19 using EMC or DMC as a low viscosity and low dielectric constant solvent were 2 to 6% better than the battery 17 using DEC. On the other hand, when the capacity retention rate after 500 cycles of the batteries 15, 20, and 21 having the 5V-class positive electrode active material was compared, it was found that the batteries 15 and 21 using EMC or DMC were about 10 to 40% higher than the battery 20 using DEC, and a significant effect was confirmed. Further, the significant effect of using EMC or DMC was also confirmed when the capacity retention rates at the time after 300 cycles were compared for the batteries 15, 20, and 21.
From the above results, it was found that a significant effect of improving cycle characteristics was exhibited in a battery using a 5V class active material by using EMC or DMC as a low viscosity and low dielectric constant solvent.
Then, the following studies were made to clarify the reason why it is preferable to use EMC or DMC as a solvent having a low viscosity and a low dielectric constant.
In the battery with the decreased cycle capacity, the difference between the charge/discharge capacity value at 1C (high rate) and the charge/discharge capacity value at 0.1C (low rate) becomes large. This phenomenon is considered to be caused by an increase in impedance within the battery.
Here, when the resistance increasing portion is R and the current value is I, a high voltage corresponding to IR is required to charge to the design capacity. However, in the charging of the lithium ion secondary battery, the charging is stopped when a predetermined voltage is reached or the charging is performed for a certain period of time at a low voltage thereafter, and therefore, the charging is terminated in a state where the original design capacity is not fully charged. Therefore, the larger the impedance increase R or the larger the current value I, the smaller the charge/discharge capacity value. According to this phenomenon, as R increases, the difference between the capacity value at a high rate and the capacity value at a low rate becomes remarkable.
Table 3 shows the results obtained for the use of LiNi0.5Mn1.35Ti0.15O4The table shows values of (1C charge/discharge capacity)/(0.1C charge/discharge capacity) after 300 cycles for batteries 20, 21, and 15 using amorphous carbon as a negative electrode active material and EC/DEC, EC/EMC, and EC/DMC as solvents as a positive electrode active material.
TABLE 3
| Battery with a battery cell | Positive electrode active material | Solvent composition and volume ratio | Negative electrode active material | (1C Charge-discharge Capacity)/(0.1C Charge-discharge Capacity) |
| 20 | LiNi0.5Mn1.35Ti0.15O4 | EC/DEC＝40/60 | Amorphous carbon | 60％ |
| 21 | LiNi0.5Mn1.35Ti0.15O4 | EC/EMC＝40/60 | Amorphous carbon | 67％ |
| 15 | LiNi0.5Mn1.35Ti0.15O4 | EC/DMC＝40/60 | Amorphous carbon | 81％ |
As shown in table 3, the value of (1C charge/discharge capacity)/(0.1C charge/discharge capacity) after 300 cycles differs depending on the solvent used, and the value of (1C charge/discharge capacity)/(0.1C charge/discharge capacity) was lower in the battery 20 using DEC than in the batteries 21 and 15 using EMC or DMC. From this result, it can be said that battery 20 has a larger difference in capacity value between the high rate and the low rate than battery 21 or battery 15. Therefore, it is considered that the battery 20 proceeds more remarkably with an increase in the cycle impedance when compared with the battery 21 or 15. The increase in the resistance is considered to be caused by the deposition of decomposition products of the electrolyte solution on the surface of the negative electrode.
In summary, when EMC or DMC is used as the solvent having low viscosity and low dielectric constant, the deposition amount of the decomposition product of the electrolytic solution on the surface of the negative electrode is smaller than that in the case of DEC. This is considered to contribute to improvement in cycle characteristics.
Here, in order to investigate how the volume ratio of the high-viscosity high-dielectric-constant solvent and the low-viscosity low-dielectric-constant solvent affects the value of (1C charge/discharge capacity)/(0.1C charge/dischargecapacity) in the battery using DMC as the low-viscosity low-dielectric-constant solvent, the battery shown in table 4 was evaluated.
TABLE 4
| Battery with a battery cell | Positive electrode active material | Solvent composition and volume ratio | Negative electrode active material Quality of food | (1C charge-discharge capacity) </or > (0.1C Charge-discharge Capacity) | Capacity retention rate |
| After 200 cycles at 45 DEG C | |||||
| 9 | LiNi0.5Mn1.5O4 | EC/DMC＝40/60 | Amorphous carbon | 90％ | 64％ |
| 22 | LiNi0.5Mn1.5O4 | EC/DMC＝50/50 | Amorphous carbon | 86％ | 70％ |
Battery 9 has the same configuration as battery 9 shown in table 1, and battery 22 has the same configuration as battery 9 except that the volume ratio of EC, which is a solvent having high viscosity and high dielectric constant, is 50%.
As shown in table 4, the values of (1C charge/discharge capacity)/(0.1C charge/discharge capacity) after 200 cycles were about 90% for both of the batteries 9 and 22, and no significant difference was observed, indicating that the deposition of decomposition products of the electrolyte solution on the surface of the negative electrode was small after 200 cycles. In addition, no significant difference was observed in the capacity retention rates after 200 cycles between batteries 9 and 22. From the results, it is considered that the volume ratio of EC as a solvent having high viscosity and high dielectric constant is 40 to 50%, which is suitable from the viewpoint of obtaining good cycle characteristics.
(study of Positive electrode active Material in which part of Mn was replaced with other element)
Referring back to table 1 again, the study of the positive electrode active material is shown below.
The batteries 10, 12, 14, 15, and 16 use LiNi0.5Mn1.5O4A positive electrode active material in which a part of Mn in (B) is substituted with Al, Li, Si, Ti, or Ge. When these batteries were used and LiNi was used0.5Mn1.5O4When comparing the batteries 9 as the positive electrode active materials, it was found that the positive electrode active material was formed by mixing LiNi0.5Mn1.5O4In (b), a part of Mn in (c) is substituted with the element, and the capacity retention rates after 100 cycles and after 300 cycles are further improved. Wherein LiNi is reacted with a catalyst0.5Mn1.5O4The battery 15 in which a part of Mn in (b) is substituted with Ti has very excellent cycle characteristics, and uses an active material having a higher discharge potential with respect to Li metal than other active materials, and therefore can be said to be an excellent battery from the viewpoint of energy density.
As described above, it can be inferred that by mixing LiNi0.5Mn1.5O4Part of Mn in (b) is substituted with the element, and the crystal structure of the positive electrode active material is stabilized, and deterioration is reduced.
(investigation of active Material in which part of O was replaced with F)
Batteries 11 and 13 are each a battery using a positive electrode active material obtained by replacing a part of O in the positive electrode active material of batteries 10 and 12 with F. As is clear from comparison of the batteries 10 and 11 or the batteries 12 and 13, the cycle characteristics are further improved by replacing a part of O with F.
In the reaction of LiNi0.5Mn1.5O4In the system in which a part of Mn in the alloy is substituted with an element having a valence of 1 to 3, the valence of Ni increases. The increase in the valence of Ni causes the crystal structure to be unstable and the capacity to be reduced. Therefore, in the positive electrode active materials of the batteries 11 and 13, by replacing a part of O with F, the increase in the valence number of Ni is cancelled out, that is, the instability of the crystal structure is avoided. Therefore, canThe cycle characteristics are considered to be improved. Moreover, since the capacity reduction is also avoided at the same time, the capacities of the batteries 11 and 13 are improved as compared with the batteries 10 and 12, respectively.
In the above examples, the description has been given of the battery using the spinel-type lithium manganese composite oxide as the positive electrode active material, but the battery using another active material, for example, LiCoPO4Lithium-containing olivine-type lithium-containing composite oxide such as LiNiVO4The effects described in the examples can also be obtained in a cell of an iso-spinel type lithium-containing composite oxide.
As described above, according to the present invention, it is possible to provide a secondary battery having a high operating voltage while suppressing a decrease in capacity and a decrease in reliability at high temperatures due to cycling by using an electrolytic solution containing at least one of a high dielectric constant solvent and dimethyl carbonate or ethyl methyl carbonate.
Claims (8)
1. A secondary battery comprising a positive electrode active material having an average discharge potential of 4.5V or more with respect to Li metal, and an electrolyte, wherein the electrolyte comprises a high dielectric constant solvent having a dielectric constant of 40 or more, and another solvent comprising at least one of dimethyl carbonate and ethyl methyl carbonate.
2. The secondary battery according to claim 1, further comprising a negative electrode active material containing amorphous carbon.
3. The secondary battery according to claim 1 or 2, wherein a volume ratio of the high dielectric constant solvent to the electrolyte is in a range of 10 to 70%.
4. The secondary battery according to any one of claims 1 to 3, wherein the high dielectric constant solvent is ethylene carbonate or propylene carbonate.
5. The secondary battery according to any one of claims 1 to 4, wherein the positive electrode active material is a spinel-type lithium manganese composite oxide.
6. The secondary battery according to claim 5, wherein the spinel-type lithium manganese complex oxide is represented by the following general formula (I):
Lia(NixMn2-x-yMy)(O4-wZw) (I)
(wherein x is 0.4. ltoreq. x.ltoreq.0.6, y is 0. ltoreq. y, Z is 0. ltoreq. Z, x + y is 2, w is 0. ltoreq. w.ltoreq.1, a is 0. ltoreq. a.ltoreq.1.2, M is at least one member selected from the group consisting of Li, Al, Mg, Ti, Si and Ge, and Z is at least one member selected from the group consisting of F and Cl)
The spinel-type lithium manganese complex oxide is shown.
7. The secondary battery according to claim 6, wherein y in the general formula (I) satisfies a relationship of 0<y.
8. The secondary battery according to claim 6 or 7, wherein w of the general formula (I) satisfies a relationship of 0<w.ltoreq.1.
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| JP165651/2002 | 2002-06-06 | ||
| JP2002165651A JP4281297B2 (en) | 2002-06-06 | 2002-06-06 | Secondary battery |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103328388A (en) * | 2010-11-08 | 2013-09-25 | 浦项能源材料公司 | Lithium manganese composite oxide and method for preparing same |
| CN103415951A (en) * | 2011-09-20 | 2013-11-27 | 日立麦克赛尔株式会社 | Nonaqueous secondary battery |
| CN102077405B (en) * | 2008-06-25 | 2013-12-11 | 原子能与替代能源委员会 | Non-aqueous electrolyte for a high-voltage lithium battery |
| CN103460491A (en) * | 2011-03-28 | 2013-12-18 | 日本电气株式会社 | Secondary battery and electrolyte |
| CN104247136A (en) * | 2012-04-20 | 2014-12-24 | 株式会社Lg化学 | Electrolyte for lithium secondary battery and lithium secondary battery containing same |
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| JP2005078820A (en) * | 2003-08-28 | 2005-03-24 | Japan Storage Battery Co Ltd | Non-aqueous electrolyte secondary battery |
| JP4245532B2 (en) * | 2004-08-30 | 2009-03-25 | 株式会社東芝 | Nonaqueous electrolyte secondary battery |
| JP5068459B2 (en) * | 2006-01-25 | 2012-11-07 | Ｎｅｃエナジーデバイス株式会社 | Lithium secondary battery |
| US20070259265A1 (en) * | 2006-05-02 | 2007-11-08 | Saidi M Yazid | Secondary electrochemical cell having a novel electrode active material |
| KR100801637B1 (en) * | 2006-05-29 | 2008-02-11 | 주식회사 엘지화학 | Cathode Active Material and Lithium Secondary Battery Containing Them |
| TW200840121A (en) * | 2007-03-30 | 2008-10-01 | Nippon Chemical Ind | Lithium transition metal complex oxide for lithium ion secondary battery cathode active material and method for producing the same, lithium ion secondary battery cathode active material, and lithium ion secondary battery |
| JP2008288049A (en) * | 2007-05-18 | 2008-11-27 | Toyota Central R&D Labs Inc | Lithium ion secondary battery |
| WO2012141301A1 (en) | 2011-04-13 | 2012-10-18 | 日本電気株式会社 | Lithium secondary cell |
| WO2014103893A1 (en) * | 2012-12-26 | 2014-07-03 | 日本電気株式会社 | Lithium secondary battery and method for selecting same |
| JP5741970B2 (en) * | 2013-08-05 | 2015-07-01 | 戸田工業株式会社 | Lithium composite compound particle powder and method for producing the same, non-aqueous electrolyte secondary battery |
| JPWO2016171276A1 (en) * | 2015-04-24 | 2017-11-24 | 日立化成株式会社 | Lithium ion battery |
| JP6825701B2 (en) * | 2016-10-06 | 2021-02-03 | 日本電気株式会社 | Spacer-containing electrode structure and its application to high energy density and fast-chargeable lithium-ion batteries |
| WO2018138865A1 (en) * | 2017-01-27 | 2018-08-02 | Nec Corporation | Silicone ball containing electrode and lithium ion battery including the same |
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| US5192629A (en) * | 1992-04-21 | 1993-03-09 | Bell Communications Research, Inc. | High-voltage-stable electrolytes for Li1+x Mn2 O4 /carbon secondary batteries |
| JPH07254434A (en) * | 1994-03-14 | 1995-10-03 | Fuji Elelctrochem Co Ltd | Nonaqueous electrolyte for lithium battery |
| US6030726A (en) * | 1996-06-17 | 2000-02-29 | Hitachi, Ltd. | Lithium secondary battery having negative electrode of carbon material which bears metals |
| JP2001148249A (en) * | 1999-11-19 | 2001-05-29 | Chuo Denki Kogyo Co Ltd | Negative electrode active material for lithium secondary battery and lithium secondary battery |
| JP2001319653A (en) * | 2000-05-12 | 2001-11-16 | Hitachi Maxell Ltd | Non-aqueous secondary battery |
-
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| CN102077405B (en) * | 2008-06-25 | 2013-12-11 | 原子能与替代能源委员会 | Non-aqueous electrolyte for a high-voltage lithium battery |
| CN103328388A (en) * | 2010-11-08 | 2013-09-25 | 浦项能源材料公司 | Lithium manganese composite oxide and method for preparing same |
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| CN103415951A (en) * | 2011-09-20 | 2013-11-27 | 日立麦克赛尔株式会社 | Nonaqueous secondary battery |
| CN103415951B (en) * | 2011-09-20 | 2016-01-20 | 日立麦克赛尔株式会社 | Non-aqueous secondary batteries |
| CN104247136A (en) * | 2012-04-20 | 2014-12-24 | 株式会社Lg化学 | Electrolyte for lithium secondary battery and lithium secondary battery containing same |
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| WO2003105267A1 (en) | 2003-12-18 |
| JP2004014270A (en) | 2004-01-15 |
| JP4281297B2 (en) | 2009-06-17 |
| CN100347902C (en) | 2007-11-07 |
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