WO2014024924A1 - リチウム二次電池用正極活物質とその製造方法、及び、リチウム二次電池用正極とその正極を備えるリチウム二次電池 - Google Patents
リチウム二次電池用正極活物質とその製造方法、及び、リチウム二次電池用正極とその正極を備えるリチウム二次電池 Download PDFInfo
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- H01M4/00—Electrodes
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- C01G23/003—Titanates
- C01G23/005—Alkali titanates
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- C01G49/00—Compounds of iron
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- C01G49/0027—Mixed oxides or hydroxides containing one alkali metal
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- 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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- 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
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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- 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
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- 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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- 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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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
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- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
- C01P2006/82—Compositional purity water content
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- H—ELECTRICITY
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- 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
- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to a positive electrode active material for a lithium secondary battery, a method for producing the same, and a positive electrode for a lithium secondary battery and a lithium secondary battery.
- iron-containing lithium titanate has been used as one of positive electrode materials for lithium secondary batteries.
- a method for producing iron-containing lithium titanate for example, a co-precipitation mixture obtained by co-precipitation and aging of a Ti source and an Fe source as starting materials is mixed in a strong alkali containing a Li source, There has been proposed a method of synthesizing a desired product through a process of hydrothermal treatment, washing with water and drying.
- Patent Document 1 Japanese Patent No. 3914981 (Patent Document 1), as a cathode material for lithium secondary battery, the compositional formula Li 2-x Ti 1-z Fe z O 3-y (0 ⁇ x ⁇ 2,0 ⁇ y ⁇ 1, 0.05 ⁇ z ⁇ 0.95), and a lithium ferrite oxide having a cubic rock salt structure is described. Further, as a method for producing this lithium ferrite-based oxide, a mixed aqueous solution containing a water-soluble titanium salt and a water-soluble iron salt is coprecipitated with an alkali, and the resulting precipitate together with an oxidizing agent and a water-soluble lithium compound is added in 101- A method is described which comprises hydrothermally treating in the temperature range of 400 ° C.
- the positive electrode material for lithium ion secondary batteries which consists of the above-mentioned lithium ferrite type oxide, and a lithium ion secondary battery are described.
- Patent Document 2 discloses a method for synthesizing lithium iron oxide having a step of heating a starting material containing at least iron oxyhydroxide and a lithium compound in an atmosphere containing water vapor. Is described. In addition, an electrode including a lithium iron oxide represented by Li x FeO 2 (0 ⁇ x ⁇ 2) having a zigzag layer structure and an electrolyte layer having at least lithium ion conductivity, obtained by the synthesis method described above. A lithium battery is described.
- Patent Document 3 discloses a lithium iron oxide represented by Li x FeO 2 (where 0 ⁇ x ⁇ 2) having the same type of tunnel structure as that of akaganeate ⁇ -FeO (OH) Is described. Also described is a method for producing the above lithium iron oxide, characterized in that an alcohol suspension containing akaganeate ⁇ -FeO (OH) and a lithium compound is heated to a temperature of 50 ° C. or higher. Further, there is described a lithium battery including a lithium ion conductive electrolyte and a pair of electrodes, and at least one of the pair of electrodes includes the above-described lithium iron oxide.
- Patent Documents 1 to 3 have storage characteristics (characteristics for suppressing voltage drop during storage) when used as a positive electrode active material of a lithium secondary battery. In that respect, it was insufficient.
- the unreacted Li source remains on the surface of the iron-containing lithium titanate even after the subsequent water washing process. Will remain.
- an unreacted Li source remains on the surface of the iron-containing lithium titanate, and is likely to react with moisture in the air. Therefore, when such iron-containing lithium titanate is used as a positive electrode material for a lithium secondary battery, the storage characteristics deteriorate due to the influence of adhering moisture (elements such as Fe elute during high-temperature storage or gas during charge-discharge). The voltage drop due to the occurrence of (or the like) occurs.
- the iron-containing lithium titanate obtained by the hydrothermal reaction method described in Patent Document 1 retains an alkaline component such as a Li source, the active material itself has a high pH. become. For this reason, when used in a lithium secondary battery, the binder is deteriorated to cause gelation, and there is a problem in that the coating is adversely affected.
- the present inventors have conducted a mechanochemical treatment of iron-containing lithium titanate with a carbonaceous material to preserve lithium secondary batteries when used as a positive electrode active material for lithium secondary batteries.
- the knowledge that the positive electrode active material for lithium secondary batteries which can improve a characteristic and an initial stage battery characteristic can be obtained was acquired.
- the knowledge that the lithium secondary battery which was more excellent in a storage characteristic and an initial stage battery characteristic can be obtained by making a crystallite diameter, a moisture content, a specific surface area, etc. into a specific range was acquired.
- the amount of Li source to be used can be reduced, and iron-containing lithium titanate can be produced in a short time. Obtained knowledge. As a result, the unreacted Li source remaining on the surface of the iron-containing lithium titanate can be reduced.
- iron-containing lithium titanate is used as the positive electrode active material of a lithium secondary battery, elution of elements such as Fe during high temperature storage and generation of gas during charge / discharge due to moisture adsorption. From this point, it was found that a lithium secondary battery having excellent storage characteristics can be obtained.
- the present invention has been made in view of the above-described conventional problems, and can provide a lithium secondary battery that is superior in storage characteristics (characteristics for suppressing a voltage drop during storage) as compared with the prior art.
- the object is to provide a positive electrode active material for a lithium secondary battery.
- Another object of the present invention is to provide a production method capable of obtaining such a positive electrode active material in an extremely short time and at a low cost.
- the positive electrode active material for a lithium secondary battery according to the present invention has a cubic rock salt type structure and has a composition formula Li 1 + x (Ti 1-y Fe y ) 1-x O 2 (0 ⁇ x ⁇ 0.3, 0
- the iron-containing lithium titanate represented by ⁇ y ⁇ 0.8) and a carbonaceous material are included, and the iron-containing lithium titanate and the carbonaceous material are combined by mechanochemical treatment.
- the positive electrode active material for a lithium secondary battery according to the present invention preferably contains 0.5 to 10 wt% of a carbonaceous material.
- the positive electrode active material for a lithium secondary battery according to the present invention preferably has a crystallite diameter of iron-containing lithium titanate of 5 to 100 nm.
- the positive electrode active material for a lithium secondary battery according to the present invention preferably has a water content of 2000 ppm or less.
- the positive electrode active material for a lithium secondary battery according to the present invention preferably has a specific surface area by the BET method of 20 to 150 m 2 / g.
- the positive electrode active material for a lithium secondary battery according to the present invention preferably has a voltage drop rate calculated from the following formula of 5% or less.
- (Voltage drop rate) ((Voltage immediately after charging-Voltage measured after storage for 30 days) / (Voltage immediately after charging)) x 100 (%)
- a solution containing an Fe source and a Ti source is neutralized with an alkaline solution, washed with water, and dried to obtain a Fe—Ti coprecipitate.
- a compounding process in which a precipitation process, a mixing process in which a coprecipitate is mixed with a Li source to obtain a mixture, a firing process in which the mixture is fired to obtain a fired product, and a fired product and a carbonaceous material are combined by mechanochemical treatment. Process.
- the firing step is preferably performed in an inert gas atmosphere.
- the firing step is preferably performed at a temperature of 400 ° C. or higher and 700 ° C. or lower.
- a solution containing an Fe source and a Ti source is neutralized with an alkaline solution, washed with water, and dried to obtain a Fe—Ti coprecipitate.
- a precipitation step a mixing step in which a coprecipitate is mixed with a Li source to obtain a mixture, a synthesis step in which the mixture is irradiated with microwaves to synthesize iron-containing lithium titanate, an iron-containing lithium titanate and a carbonaceous material
- a compounding step of compounding with a mechanochemical treatment is performed in the method for producing a positive electrode active material for a lithium secondary battery according to the present invention.
- the synthesis step is preferably performed at a temperature of 100 ° C. or higher and 250 or lower.
- the Fe source is any one or more of Fe 2 (SO 4 ) 3 , FeSO 4 , FeCl 3 , and Fe (NO 3 ) 3. Preferably there is.
- the Ti source is preferably any one or more of Ti (SO 4 ) 2 , TiOSO 4 , and TiCl 4 .
- the positive electrode for a lithium secondary battery according to the present invention has a layer made of any of the above-described positive electrode active materials for a lithium secondary battery on the current collector surface.
- a lithium secondary battery according to the present invention includes the above-described positive electrode for a lithium secondary battery.
- a positive electrode active material for a lithium secondary battery that is low in cost during synthesis of a positive electrode active material for a lithium secondary battery and has good storage stability after the production of the lithium secondary battery,
- a manufacturing method, a positive electrode provided with the positive electrode active material for lithium secondary batteries, and a lithium secondary battery provided with the same can be provided.
- the lithium secondary battery is more excellent in storage characteristics and initial battery characteristics by making the crystallite diameter, moisture content, specific surface area and the like into a specific range. Can be obtained.
- iron-containing lithium titanate is synthesized by irradiating microwaves, nucleation is possible without extra side reactions. It becomes.
- it is possible to obtain a uniform crystal in a short time of synthesis it is possible to suppress consumption due to oxidation of the Li source, and to reduce the amount of Li source to be mixed.
- the unreacted Li source remaining on the surface of the iron-containing lithium titanate even after the synthesis can be reduced.
- iron-containing lithium titanate is mechanochemically treated with a carbonaceous material, a lithium secondary battery excellent in storage characteristics and initial battery characteristics can be obtained when used as a positive electrode active material of a lithium secondary battery. .
- the positive electrode active material for a lithium secondary battery according to the present invention has a cubic rock salt type structure and has a composition formula Li 1 + x (Ti 1-y Fe y ) 1-x O 2 (0 ⁇ x ⁇ 0.3, 0
- the iron-containing lithium titanate represented by ⁇ y ⁇ 0.8) and a carbonaceous material are included, and the iron-containing lithium titanate and the carbonaceous material are combined by mechanochemical treatment.
- Examples of the raw material (Fe source, Ti source, Li source, alkaline solution, carbonaceous material) of the positive electrode active material for a lithium secondary battery according to the present invention include the following.
- the Fe source is preferably one or more of Fe 2 (SO 4 ) 3 , FeSO 4 , FeCl 3 , and Fe (NO 3 ) 3 . Such Fe sources may be used alone or in combination. Of these, Fe 2 (SO 4 ) 3 is more preferably used as the Fe source in consideration of the cost and the handling surface during crystallization.
- Ti source is preferably at least one of Ti (SO 4 ) 2 , TiOSO 4 , and TiCl 4 . Such Ti sources may be used alone or in combination. Of these, TiOSO 4 is more preferably used as the Ti source in consideration of dissolution in water and the like.
- the Li source is preferably, for example, Li 2 CO 3 , LiOH ⁇ H 2 O, or CH 3 COOLi.
- this Li source may be used independently and can also be used together. Of these, considering the cost and reactivity, it is preferable to use LiOH.H 2 O.
- alkaline solution examples include aqueous solutions of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, and the like. Among these, it is preferable to use an aqueous ammonia solution from the viewpoint of suppressing residual elements such as sodium which are considered to affect the battery performance.
- the carbonaceous material examples include acetylene black, ketjen black, carbon black, artificial graphite, graphite, carbon nanotube, and graphene. Such carbonaceous materials may be used alone or in combination. Of these, ketjen black is preferably used from the viewpoint of conductivity, dispersibility, and cost.
- the positive electrode active material for a lithium secondary battery preferably contains 0.5 to 10 wt% of a carbonaceous material, and more preferably contains 0.5 to 5.0 wt%. By making the content of the carbonaceous material 0.5 wt% or more, the effect of improving the electron conductivity can be further enhanced.
- the carbonaceous material 10 wt% or less, moisture adsorption by the carbonaceous material can be further suppressed, and the storage stability can be further improved.
- the positive electrode which comprised the positive electrode active material for lithium secondary batteries as a positive electrode material by making the carbonaceous material in the positive electrode active material for lithium secondary batteries 10 wt% or less the filling amount of the active material itself in the electrode Can be prevented from decreasing.
- the positive electrode active material for a lithium secondary battery according to the present invention has a composition formula with a crystallite diameter of 5 to 100 nm and Li 1 + x (Ti 1-y Fe y ) 1-x O 2 (0 ⁇ x ⁇ 0. It is preferable to use iron-containing lithium titanate represented by 3, 0 ⁇ y ⁇ 0.8). Thus, by using iron-containing lithium titanate containing iron in the above-mentioned ratio and having a crystallite diameter in a specific range, it is possible to improve the storage characteristics when used in a lithium secondary battery. A positive electrode active material for a secondary battery can be obtained.
- the reason why the crystallite size is important in the present invention is that the diffusion distance in the crystal is the initial battery capacity when Li insertion / extraction occurs from the iron-containing lithium titanate crystal during charge / discharge. It is because it affects the size.
- the crystallite diameter may be in the range of 5 to 100 nm, but is preferably 10 to 80 nm, more preferably 10 to 40 nm from the viewpoint of initial battery capacity.
- the positive electrode active material for a lithium secondary battery according to the present invention preferably has a water content of 2000 ppm or less, and more preferably 1000 ppm or less.
- the amount of Li source to be used can be reduced, and the resulting surface of the iron-containing lithium titanate Since the unreacted Li source remaining on the surface can be reduced, the water content can be made lower.
- the positive electrode active material for a lithium secondary battery according to the present invention can obtain iron-containing lithium titanate having a small particle diameter by using a microwave.
- the positive electrode active material for a lithium secondary battery after mechanochemical treatment with the carbonaceous material also has a small particle size.
- the specific surface area by the BET method is preferably 20 to 150 m 2 / g, more preferably 70 to 120 m 2 / g, still more preferably 80 to 110 m 2 / g.
- a solution containing Fe source and Ti source is neutralized with an alkaline solution, washed with water, and dried to obtain a Fe—Ti coprecipitate, and the mixture is mixed with the Li source.
- the method includes a mixing step to obtain, a firing step for firing the mixture to obtain a fired product, and a compounding step for combining the fired product and the carbonaceous material by mechanochemical treatment.
- the firing step is preferably performed in an inert gas atmosphere.
- an inert gas atmosphere By doing in this way, reaction to Fe oxide of Fe source can be controlled.
- a gas such as argon, helium, or nitrogen can be used. In consideration of utility costs during mass production, nitrogen gas is more preferably used as the inert gas.
- the firing step is preferably performed at a temperature of 400 ° C. or higher and 700 ° C. or lower.
- the calcination temperature is set to 400 ° C. or higher, the synthesis reaction can be made to proceed completely, and unreacted products and intermediate products can be eliminated.
- the firing temperature is set to 700 ° C. or lower, particle growth can be prevented, and relatively large particles can be prevented from affecting Li diffusion during charge / discharge and deteriorating battery performance.
- a Fe-Ti coprecipitate is obtained by neutralizing a solution containing an Fe source and a Ti source with an alkaline solution, washing with water and drying.
- a coprecipitation step a mixing step in which the coprecipitate is mixed with a Li source to obtain a mixture, a synthesis step in which the mixture is irradiated with microwaves to synthesize iron-containing lithium titanate, and a composite and a carbonaceous material.
- the equipment can be labor-saving and the manufacturing cost can be reduced.
- the temperature at the time of synthesis (during microwave irradiation) and the heating time (holding time) are not particularly limited, and can be appropriately adjusted so that the Fe—Ti coprecipitate and the Li source react without excess or deficiency. .
- the temperature during the synthesis is preferably 100 to 250 ° C. (more preferably 150 to 240 ° C.), and the heating time (retention time) during the synthesis is preferably 5 minutes to 120 minutes (more preferably 30 to 60 minutes) is preferable.
- the output of the microwave is not particularly limited. If the above temperature can be realized, the output of 500 W as used in a general home microwave oven can be synthesized.
- Mechanochemical treatment refers to changing the properties of a target substance by applying mechanical energy through operations such as shearing, compression, stretching, and friction.
- iron-containing lithium titanate and a carbonaceous material are physically treated. There is an effect to combine strongly.
- the mechanochemical treatment includes, for example, a ball mill using media such as a planetary ball mill, Nobilta (registered trademark) manufactured by Hosokawa Micron Corporation, a hybridization system (registered trademark) manufactured by Nara Machinery Co., Ltd. Equipment such as a speed mixer can be used.
- the layer which consists of one of said positive electrode active materials for lithium secondary batteries can be formed in the surface of an electrical power collector, and the positive electrode for lithium secondary batteries can be comprised.
- the positive electrode active material for a lithium secondary battery according to the present invention has various technical characteristics such as the basic structure, physical properties, and manufacturing method as described above, and thus remains unreacted on the surface of the iron-containing lithium titanate.
- the voltage drop rate calculated from the following equation can be 5% or less.
- a lithium ion secondary battery can be manufactured by a well-known method using the positive electrode formed using the iron-containing lithium titanate of this invention, the well-known negative electrode, and electrolyte solution.
- the negative electrode for example, metallic lithium, a carbon-based material (activated carbon, graphite), or the like can be used.
- the electrolytic solution for example, a solution in which a lithium salt such as lithium perchlorate or LiPF 6 is dissolved in a solvent such as ethylene carbonate or dimethyl carbonate can be used.
- the lithium secondary battery of the present invention can further include other known elements as constituent elements of the battery.
- Example 1 Titanyl sulfate (TiOSO 4 , manufactured by Teika Co., Ltd.) and ferric sulfate (Fe 2 (SO 4 ) 3 ) are weighed so that the Fe / Ti ratio is 1, dissolved in water at 60 ° C., and iron- A titanium mixed solution was prepared. While stirring water, an iron-titanium mixed solution and a 28% aqueous ammonia solution as a neutralizing agent were added simultaneously while stirring to crystallize iron and titanium while maintaining the pH at 8. The crystallized coprecipitate was filtered, washed with water, dried and pulverized to obtain a Fe—Ti coprecipitate.
- TiOSO 4 manufactured by Teika Co., Ltd.
- Fe 2 (SO 4 ) 3 ferric sulfate
- Lithium hydroxide monohydrate LiOH.H 2 O was added to the Fe—Ti coprecipitate and mixed with a planetary ball mill (manufactured by Fritsch). The mixture was fired at 500 ° C. for 5 hours in a nitrogen atmosphere to obtain iron-containing lithium titanate.
- Add ketjen black (EC600JD manufactured by Lion Co., Ltd.) as a carbonaceous material to 5wt% of iron-containing lithium titanate, and use a planetary ball mill to perform mechanochemical treatment under the conditions of a rotation speed of 300rpm and a treatment time of 30 minutes.
- a positive electrode active material for a lithium secondary battery of Example 1 was produced.
- Example 2 A positive electrode active material for a lithium secondary battery of Example 2 was produced in the same manner as in the production method described in Example 1, except that the Fe source was changed to iron (III) chloride (FeCl 3 ).
- Example 3 A positive electrode active material for a lithium secondary battery of Example 3 was produced in the same manner as in the production method described in Example 1, except that the Fe source was changed to ferrous sulfate (FeSO 4 ).
- Example 4 A positive electrode active material for a lithium secondary battery of Example 4 was produced in the same manner as in the production method described in Example 1, except that the Ti source was changed to titanium sulfate (Ti (SO 4 ) 2 ).
- Example 5 A positive electrode active material for a lithium secondary battery of Example 5 was produced in the same manner as in the production method described in Example 1, except that the Ti source was changed to titanium tetrachloride (TiCl 4 ).
- Example 6 A positive electrode active material for a lithium secondary battery of Example 6 was prepared by performing the same operation as in the manufacturing method described in Example 1 except that the amount of ketjen black to be added was changed to 2.5 wt% in the composite process. did.
- Example 7 A positive electrode active material for a lithium secondary battery of Example 7 was prepared in the same manner as in the manufacturing method described in Example 1 except that the amount of ketjen black to be added was changed to 10 wt% in the composite step.
- Example 8 In the composite step, the same operation as in the production method described in Example 1 was performed except that the amount of ketjen black to be added was changed to 0.5 wt%, and a positive electrode active material for a lithium secondary battery of Example 8 was produced. did.
- Example 9 The lithium secondary battery of Example 9 was operated in the same manner as in the production method described in Example 1, except that the molar ratio of iron to titanium (Fe / Ti ratio) was changed to 2.3 in the coprecipitation step. A positive electrode active material was prepared.
- Example 10 The lithium secondary battery of Example 10 was operated in the same manner as in the production method described in Example 1, except that the molar ratio of iron and titanium (Fe / Ti ratio) was changed to 0.4 in the coprecipitation step. A positive electrode active material was prepared.
- Example 11 A positive electrode active material for a lithium secondary battery of Example 11 was produced in the same manner as in the production method described in Example 1, except that the firing temperature was changed to 450 ° C.
- Example 12 A positive electrode active material for a lithium secondary battery of Example 12 was produced in the same manner as in the production method described in Example 1, except that the firing temperature was changed to 650 ° C.
- Comparative Example 1 About the comparative example 1, the iron containing lithium titanate was produced by synthesize
- iron-containing lithium titanate was produced. Further, a lithium secondary battery using this iron-containing lithium titanate as a positive electrode material was produced. And this iron-containing lithium titanate was made into the positive electrode active material for lithium secondary batteries of the comparative example 2, without performing a mechanochemical process with a carbonaceous material.
- Lithium hydroxide monohydrate LiOH.H 2 O was added to the Fe—Ti coprecipitate and mixed with a planetary ball mill (manufactured by Fritsch). The mixture was fired at 500 ° C. for 5 hours in a nitrogen atmosphere to obtain iron-containing lithium titanate. Add 5 wt% Ketjen Black EC600JD (Lion Corporation) to the obtained iron-containing lithium titanate and mix for 30 minutes at a rotational speed of 2000 rpm using a Henschel mixer (registered trademark) made by Mitsui Mining Co., Ltd. Thus, a positive electrode active material for a lithium secondary battery of Comparative Example 3 was obtained.
- the contents of Li, Ti, and Fe were analyzed with an ICP-AES apparatus (manufactured by SII Nano Technology Co., Ltd.) by ICP emission spectroscopy.
- the amount of carbon was measured using a CN macro coder (manufactured by J Science Co., Ltd.).
- the amount of moisture was measured using a moisture analyzer by the Karl Fischer method (manufactured by Mitsubishi Materials Corporation).
- the powder conductivity was calculated by measuring the powder resistance after pressing at 20 kN using a powder resistance measurement system MCP-PD51 (Mitsubishi Chemical Analytic Co., Ltd.).
- the green compact density was calculated by using a tablet molding machine (manufactured by Ichihashi Seiki Kogyo Co., Ltd.) to pressurize at 10 kN to produce tablets and measure the tablet weight and height.
- each of Examples 1 to 12 shows a higher value in the green density than Comparative Examples 1 to 3.
- a carbonaceous material such as ketjen black was simply mixed as in Comparative Example 3, the conductivity was improved as compared with the iron-containing lithium titanate of other Comparative Examples, but the green density was not increased. From this, it is considered that in Examples 1 to 12, the density of the dust was improved by applying a mechanochemical treatment to physically and strongly bond carbon and iron-containing lithium titanate.
- lithium secondary batteries of Examples 13 to 24 were produced as follows using the produced positive electrode active materials for Examples 1 to 12 lithium secondary batteries.
- acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.
- polyvinylidene fluoride manufactured by Kureha Co., Ltd.
- a binder was each added to the positive electrode active material for the lithium secondary battery of Example 1 at 8: Weighed at a ratio of 1: 1, added an appropriate amount of N-methylpyrrolidone as a solvent and kneaded to prepare a slurry.
- the prepared slurry was applied to an aluminum foil and dried to prepare an electrode plate, and then punched into a circle with a punching machine.
- LiPF 6 EC / DEC 1/2 vol% (manufactured by Kishida Chemical Co., Ltd.) is added as an electrolyte, and a polyolefin separator (manufactured by Asahi Kasei Co., Ltd.) is stacked.
- a lithium secondary battery of Example 13 was fabricated by placing a Li metal as a counter electrode thereon and covering with a caulking machine. The lithium secondary battery was assembled in a glove box in an argon atmosphere.
- lithium secondary batteries of Examples 14 to 24 were produced in the same manner as Example 13.
- Lithium secondary batteries of Comparative Examples 4 to 6 were produced in the same manner as Example 13, except that the positive electrode active materials for lithium secondary batteries of Comparative Examples 1 to 3 were used as the positive electrode material.
- any of the lithium secondary batteries of Examples 13 to 24 has a charge / discharge capacity equal to or higher than that of the lithium secondary batteries of Comparative Examples 4 to 6. ing.
- the characteristics of Comparative Example 5 are greatly inferior to those of the other examples, but this is considered to be due to the influence of particle growth due to the mixed state of Ti and Fe and high-temperature firing.
- any of the lithium secondary batteries of Examples 13 to 24 is excellent in that the voltage drop is suppressed as compared with the lithium secondary batteries of Comparative Examples 4 to 6. This is because the lithium secondary batteries of Comparative Examples 4 to 6 have a large amount of water, so HF generated by the reaction between the water and the electrolyte solution elutes Fe and Ti on the surface of the iron-containing lithium titanate, which causes a voltage drop. It is thought to be caused by
- a positive electrode active material for a lithium secondary battery is prepared by a manufacturing method including a synthesis step of synthesizing iron-containing lithium titanate by irradiating microwaves, and the positive electrode active material for the lithium secondary battery is used to make lithium A secondary battery was produced.
- Example 25 titanyl sulfate (TiOSO 4 , manufactured by Teika Co., Ltd.) and ferric sulfate (Fe 2 (SO 4 ) 3 ) are weighed so that the molar ratio of Fe to Ti is 1, and dissolved in water at 60 ° C. Thus, an Fe—Ti mixed solution was prepared. Next, the Fe—Ti mixed solution and the 28% aqueous ammonia solution as a neutralizing agent were simultaneously added to a container containing water while stirring, and crystallization was performed while maintaining the pH at about 8. Next, the crystallized coprecipitate was filtered, washed with water, dried and pulverized to obtain a Fe—Ti coprecipitate.
- TiOSO 4 manufactured by Teika Co., Ltd.
- Fe 2 (SO 4 ) 3 ferric sulfate
- ketjen black (EC600JD manufactured by Lion Co., Ltd.) as a carbonaceous material is added to the iron-containing lithium titanate at 2 wt%, and a planetary ball mill is used under the conditions of a rotation speed of 300 rpm and a processing time of 30 minutes.
- a positive electrode active material for a lithium secondary battery of Example 25 was produced by performing a mechanochemical treatment.
- Example 26 A positive electrode active material for a lithium secondary battery of Example 26 was produced in the same manner as in Example 25 except that the Fe source was changed to iron (III) chloride (FeCl 3 ).
- Example 27 A positive electrode active material for a lithium secondary battery of Example 27 was produced in the same manner as in Example 25 except that the Fe source was changed to ferrous sulfate (FeSO 4 ).
- Example 28 A positive electrode active material for a lithium secondary battery of Example 28 was produced in the same manner as in Example 25 except that the Ti source was changed to titanium sulfate (Ti (SO 4 ) 2 ).
- Example 29 A positive electrode active material for a lithium secondary battery of Example 29 was produced in the same manner as in Example 25 except that the Ti source was changed to titanium tetrachloride (TiCl 4 ).
- Example 30 A positive electrode active material for a lithium secondary battery of Example 30 was produced in the same manner as in Example 25 except that the holding time at the time of microwave irradiation was changed to 10 minutes.
- Example 31 A positive electrode active material for a lithium secondary battery of Example 31 was produced in the same manner as in Example 25 except that the holding time during microwave irradiation was changed to 40 minutes.
- Example 32 A positive electrode active material for a lithium secondary battery of Example 32 was produced in the same manner as in Example 25 except that the holding time during microwave irradiation was changed to 60 minutes.
- Example 33 A positive electrode active material for a lithium secondary battery of Example 33 is produced in the same manner as in Example 25 except that the molar ratio of iron to titanium (Fe / Ti ratio) is changed to 2.3 in the coprecipitation step. did.
- Example 34 A positive electrode active material for a lithium secondary battery of Example 34 is produced in the same manner as in Example 25 except that the molar ratio of iron and titanium (Fe / Ti ratio) is changed to 0.3 in the coprecipitation step. did.
- Example 35 A positive electrode active material for a lithium secondary battery of Example 35 was produced in the same manner as in Example 25 except that the synthesis temperature during microwave irradiation was changed to 150 ° C.
- Example 36 A positive electrode active material for a lithium secondary battery of Example 36 was produced in the same manner as in Example 25 except that the synthesis temperature during microwave irradiation was changed to 240 ° C.
- the crystallite diameter, the contents of Li, Ti, and Fe The water content and carbon content were measured and the crystal structure was analyzed. Specifically, the crystallite size was measured using an X-ray diffraction analyzer (manufactured by Panalical). The contents of Li, Ti, and Fe were measured by ICP emission spectroscopic analysis using an ICP-AES apparatus (manufactured by SII Nano Technology). About the moisture content, it measured by the Karl Fischer method using the moisture analyzer (made by Mitsubishi Materials Corporation). The specific surface area was measured by the BET method. About the amount of carbon, it measured using CN macrocoder (made by J Science Co., Ltd.). The results are shown in Table 3.
- Example 25 All the positive electrode active material for a lithium secondary battery of ⁇ 36, LiTiO 2 and LiFeO 2 with cubic rock salt structure as described in the known X-ray powder diffraction data Can be indexed by unit cells.
- the positive electrode active materials for lithium secondary batteries of Comparative Examples 1 and 2 had a crystallite diameter exceeding 100 nm and a specific surface area lower than 20 m 2 / g.
- the positive electrode active material for the lithium secondary battery of Comparative Example 1 had a very high water content of 7200 ppm.
- lithium secondary batteries of Examples 37 to 48 were produced by the production method of Paragraph [0077], and Comparative Example 4, The storage characteristics were evaluated together with 5 lithium secondary batteries. The results are shown in Table 4.
- the positive electrode active material for a lithium secondary battery of the present invention when used in a lithium secondary battery as a positive electrode active material, it is possible to obtain a lithium secondary battery that is superior in storage characteristics as compared with conventional ones. I understood that I can do it.
- the method for producing a positive electrode active material of the present invention the unreacted Li source remaining on the surface of the iron-containing lithium titanate after synthesis can be reduced, and the positive electrode active material of the lithium secondary battery can be reduced. It was found that when used, a lithium secondary battery having excellent storage characteristics can be obtained. It was also found that such a positive electrode active material can be obtained in a very short time and at a low cost.
- the present invention can be used for a positive electrode active material of a lithium secondary battery.
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Abstract
Description
そしてその結果、鉄含有チタン酸リチウムの表面上に残存する未反応のLi源を削減することができる。そしてかかる鉄含有チタン酸リチウムをリチウム二次電池の正極活物質に使用した際には、水分が吸着することに起因する高温保存時におけるFeなどの元素の溶出や充放電時におけるガスの発生を抑制することができ、この点からも保存特性に優れるリチウム二次電池を得ることができるという知見を得た。
(電圧降下率)=((充電直後の電圧-30日保存後測定時電圧)/(充電直後の電圧))×100(%)
また、合成を短時間でかつ均一な結晶を得ることが可能であり、Li源の酸化による消費を抑制することができるとともに、混合するLi源の量を削減することができる。その結果、合成後においても鉄含有チタン酸リチウムの表面上に残存する未反応のLi源を削減することができる。
そしてかかる鉄含有チタン酸リチウムを炭素質材料でメカノケミカル処理することによって、リチウム二次電池の正極活物質に使用した際に、保存特性、初期電池特性に優れるリチウム二次電池を得ることができる。
この発明に従ったリチウム二次電池用正極活物質は、立方晶岩塩型構造であって組成式Li1+x(Ti1-yFey)1-xO2(0<x≦0.3、0<y≦0.8)で表される鉄含有チタン酸リチウムと、炭素質材料とを含み、鉄含有チタン酸リチウムと炭素質材料とは、メカノケミカル処理によって複合化されている。
Fe源は、Fe2(SO4)3、FeSO4、FeCl3、Fe(NO3)3のいずれか1つ以上であることが好ましい。なお、かかるFe源は単独で用いても良いし、併用することもできる。そしてこの中でもコストや晶析時のハンドリング面を考慮すると、Fe源としてはFe2(SO4)3を用いることがより好ましい。
Ti源は、Ti(SO4)2、TiOSO4、TiCl4のいずれか1つ以上であることが好ましい。なお、かかるTi源は単独で用いても良いし、併用することもできる。そしてこの中でも水への溶解等を考慮すると、Ti源としてはTiOSO4を用いることがより好ましい。
Li源は、例えば、Li2CO3、LiOH・H2O、CH3COOLiであることが好ましい。なお、かかるLi源は単独で用いても良いし、併用することもできる。そしてこの中でもコストや反応性を考慮すると、LiOH・H2Oを用いることが好ましい。
アルカリ性溶液としては、アンモニア、水酸化ナトリウム、水酸化カリウム、炭酸ナトリウムなどの水溶液が挙げられる。そしてこの中でも電池性能に影響に与えると考えられるナトリウム等の残存元素抑制の点からアンモニア水溶液を用いることが好ましい。
また、リチウム二次電池用正極活物質は、炭素質材料を0.5~10wt%含むことが好ましく、0.5~5.0wt%含むことがより好ましい。炭素質材料の含有量を0.5wt%以上にすることによって、電子伝導性の向上効果をより高めることができる。また、炭素質材料を10wt%以下とすることで、炭素質材料による水分吸着をより抑え、保存安定性をより向上させることができる。また、リチウム二次電池用正極活物質中の炭素質材料を10wt%以下にすることによって、リチウム二次電池用正極活物質を正極材料として構成した正極において、電極中の活物質自体の充填量を減少させないようにすることができる。
また、本発明に係るリチウム二次電池用正極活物質は、結晶子径を5~100nmにした組成式がLi1+x(Ti1-yFey)1-xO2(0<x≦0.3、0<y≦0.8)で表される鉄含有チタン酸リチウムを用いることが好ましい。
このように上記の比率で鉄を含有し、結晶子径を特定の範囲とした鉄含有チタン酸リチウムを用いることによって、リチウム二次電池に用いた場合に保存特性を向上させることができるリチウム二次電池用正極活物質を得ることができるのである。ここで、本発明において結晶子径の大きさが重要である理由は、充放電時に鉄含有チタン酸リチウム結晶内からLiの挿入・脱離が生じる際に、結晶内の拡散距離が初期電池容量の大小に影響するからである。
なお、結晶子径については5~100nmの範囲であればよいが、初期電池容量の観点から10~80nmであることが好ましく、より好ましくは10~40nmである。
また、本発明に係るリチウム二次電池用正極活物質は、水分量が2000ppm以下であることが好ましく、その中でも1000ppm以下であることがより好ましい。
特に、後記する、鉄含有チタン酸リチウムの合成時の加熱手段にマイクロ波を用いた場合には、使用するLi源の量を削減することができ、その結果得られる鉄含有チタン酸リチウムの表面上に残存する未反応のLi源を削減することができることから、水分量をより低いものとすることができる。
さらに、本発明に係るリチウム二次電池用正極活物質は、マイクロ波を用いることによって粒径の小さな鉄含有チタン酸リチウムを得ることができる。そして、その結果炭素質材料でメカノケミカル処理した後のリチウム二次電池用正極活物質も粒径の小さなものとなる。具体的には、BET法による比表面積が20~150m2/gであることが好ましく、より好ましくは70~120m2/gであり、さらに好ましくは80~110m2/gである。
本発明に係るリチウム二次電池用正極活物質の製造方法としては、まず以下の方法がある。すなわち、Fe源とTi源とを含む溶液をアルカリ性溶液で中和し、水洗し、乾燥させてFe-Ti共沈物を得る共沈工程と、共沈物をLi源と混合して混合物を得る混合工程と、混合物を焼成して焼成物を得る焼成工程と、焼成物と炭素質材料とをメカノケミカル処理によって複合化させる複合化工程とを含む方法である。
さらに、マイクロ波の出力についても特に限定されず、上記の温度を実現できれば一般的な家庭用電子レンジで採用されているような500Wの出力でも合成することができる。
また、上記のいずれかのリチウム二次電池用正極活物質からなる層を集電体の表面に形成してリチウム二次電池用正極を構成することができる。
さらに、本発明に係るリチウム二次電池用正極活物質は、上記の通り基本構造、物性、製造方法など様々な技術的特徴を有することによって、鉄含有チタン酸リチウムの表面上に残存する未反応のLi源を削減することができ、その結果リチウム二次電池の正極活物質に使用した際には、保存特性に優れるリチウム二次電池を得ることができる。
具体的には、下式から算出される電圧降下率を5%以下とすることができる。
(電圧降下率)=((充電直後の電圧-30日保存後測定時電圧)/(充電直後の電圧))×100(%)
また、保存特性に優れるだけでなく、初期電池特性においても優れた(充電容量および放電容量が大きい、クーロン効率が高い)リチウム二次電池を得ることができる。
硫酸チタニル(TiOSO4、テイカ株式会社製)と硫酸第二鉄(Fe2(SO4)3)をFe/Ti比が1になるように秤量し、60℃の水に溶解させて、鉄-チタン混合溶液を調製した。別容器に水を入れ、撹拌しながら、鉄-チタン混合溶液と中和剤である28%アンモニア水溶液とを同時に加え、pHを8に維持しながら鉄とチタンを晶析させた。晶析した共沈物をろ過、水洗、乾燥し、粉砕してFe-Ti共沈物を得た。Fe-Ti共沈物に水酸化リチウム一水和物(LiOH・H2O)を加え、遊星ボールミル(フリッチュ社製)で混合した。混合物を窒素雰囲気下500℃で5時間焼成し、鉄含有チタン酸リチウムを得た。炭素質材料としてケッチェンブラック(ライオン株式会社製 EC600JD)を鉄含有チタン酸リチウムに対し、5wt%となるように加え、遊星ボールミルを用い、回転数300rpm、処理時間30分の条件でメカノケミカル処理を行うことによって、実施例1のリチウム二次電池用正極活物質を作製した。
Fe源を塩化鉄(III)(FeCl3)に変更する以外は実施例1記載の製造法と同様な操作を行い、実施例2のリチウム二次電池用正極活物質を作製した。
Fe源を硫酸第一鉄(FeSO4)に変更した以外は実施例1記載の製造法と同様な操作を行い、実施例3のリチウム二次電池用正極活物質を作製した。
Ti源を硫酸チタン(Ti(SO4)2)に変更した以外は実施例1記載の製造法と同様な操作を行い、実施例4のリチウム二次電池用正極活物質を作製した。
Ti源を四塩化チタン(TiCl4)に変更した以外は実施例1記載の製造法と同様な操作を行い、実施例5のリチウム二次電池用正極活物質を作製した。
複合化工程において、添加するケッチェンブラックの量を2.5wt%に変更した以外は実施例1記載の製造法と同様な操作を行い、実施例6のリチウム二次電池用正極活物質を作製した。
複合化工程において、添加するケッチェンブラックの量を10wt%に変更した以外は実施例1記載の製造法と同様な操作を行い、実施例7のリチウム二次電池用正極活物質を作製した。
複合化工程において、添加するケッチェンブラックの量を0.5wt%に変更した以外は実施例1記載の製造法と同様な操作を行い、実施例8のリチウム二次電池用正極活物質を作製した。
共沈工程において鉄とチタンのモル比率(Fe/Ti比)が2.3となるように変更した以外は実施例1記載の製造法と同様な操作を行い、実施例9のリチウム二次電池用正極活物質を作製した。
共沈工程において鉄とチタンのモル比率(Fe/Ti比)が0.4となるように変更した以外は実施例1記載の製造法と同様な操作を行い、実施例10のリチウム二次電池用正極活物質を作製した。
焼成温度を450℃に変更した以外は実施例1記載の製造法と同様な操作を行い、実施例11のリチウム二次電池用正極活物質を作製した。
焼成温度を650℃に変更した以外は実施例1記載の製造法と同様な操作を行い、実施例12のリチウム二次電池用正極活物質を作製した。
比較例1については、鉄含有チタン酸リチウムの合成時に従来の手法である水熱反応法(オートクレーブ)を用いて合成を行うことによって鉄含有チタン酸リチウムを作製した。具体的には、特許第3914981号記載の実施例1に従って、鉄含有チタン酸リチウムを作製した。そして、炭素質材料とのメカノケミカル処理を行うことなく、かかる鉄含有チタン酸リチウムを比較例1のリチウム二次電池用正極活物質とした。
Fe源に酸化鉄(III)(Fe2O3、株式会社高純度化学研究所製)、Ti源に酸化チタン(TiO2、テイカ株式会社製)、Li源に水酸化リチウム一水和物(LiOH・H2O、FMC社製)を用い、モル比率がLi:Ti:Fe=1.2:0.4:0.4になるように秤量した後、純水中で攪拌混合し、サンドグラインダーミル(株式会社シンマルエンタープライゼス製)で均一分散させた。分散液を乾燥させた後650℃で5時間、焼成を行った。このようにして、鉄含有チタン酸リチウムを作製した。また、この鉄含有チタン酸リチウムを正極材料として用いたリチウム二次電池を作製した。そして、炭素質材料とのメカノケミカル処理を行うことなく、かかる鉄含有チタン酸リチウムを比較例2のリチウム二次電池用正極活物質とした。
硫酸チタニル(TiOSO4 テイカ株式会社製)と硫酸第二鉄(Fe2(SO4)3)をFe/Ti比で1になるように秤量し、60℃の水に溶解させて、鉄-チタン混合溶液を調整した。別容器に水を加え攪拌させながら鉄-チタン混合溶液と中和剤である28%アンモニア水溶液を同時に加え、pHを8に維持しながら鉄及びチタンを晶析させた。晶析で得られた共沈物をろ過、水洗、乾燥を行い、粉砕することでFe-Ti共沈物を得た。Fe-Ti共沈物に水酸化リチウム一水和物(LiOH・H2O)を加え、遊星ボールミル(フリッチュ社製)で混合した。混合物を窒素雰囲下500℃で5時間焼成を行い、鉄含有チタン酸リチウムを得た。得られた鉄含有チタン酸リチウムに対し5wt%のケッチェンブラックEC600JD(ライオン株式会社製)を加え、三井鉱山株式会社製のヘンシェルミキサ(登録商標)を用い、回転数2000rpmで30分混合することにより、比較例3のリチウム二次電池用正極活物質とした。
また、X線回折分析装置(パナリティカル製)を用いて結晶構造解析を行ったところ、既知の粉末X線回折データに記載されている立方晶岩塩型構造をもつLiTiO2やLiFeO2の単位胞により指数付けすることができた。
次に、作製した実施例1~12リチウム二次電池用正極活物質を用いて以下の通り実施例13~24のリチウム二次電池を作製した。
また、実施例2~12のリチウム二次電池用正極活物質についても、実施例13と同様にして、実施例14~24のリチウム二次電池を作製した。
比較例1~3のリチウム二次電池用正極活物質を正極材料として用いた以外は実施例13と同様にして、比較例4~6のリチウム二次電池を作製した。
充放電装置(北斗電工株式会社製)を用いて、0.1mA/cm2で4.4Vまで定電流充電を行い、1時間の休止後、1.0Vまで定電流放電させた。このときの充電容量および放電容量を測定した。なお、これらの値が大きいほど、電池特性が良好であることを意味する。結果を表2に示す。
定電流充電を行った後、充電直後の電圧を測定した。続いて、60℃の恒温槽に入れて30日間保存した後、電圧を測定した。充電直後の電圧と30日間保存した後の電圧とから、次の式に基づいて保存時の電圧降下率を算出し、保存特性の評価を行った。なお、電圧降下率の値が小さいほど、保存特性が良好であることを意味する。結果を表2に示す。
(電圧降下率)=((充電直後の電圧-30日保存後測定時電圧)/(充電直後の電圧))×100(%)
次に、マイクロ波を照射して鉄含有チタン酸リチウムを合成する合成工程を含む製造方法によってリチウム二次電池用正極活物質を作製するとともに、かかるリチウム二次電池用正極活物質を用いてリチウム二次電池を作製した。
まず、硫酸チタニル(TiOSO4、テイカ株式会社製)と硫酸第二鉄(Fe2(SO4)3)をFeとTiのモル比が1になるように秤量し、60℃の水に溶解させて、Fe-Ti混合溶液を調製した。
次に、水を入れた容器に、Fe-Ti混合溶液と中和剤である28%アンモニア水溶液を撹拌しながら同時に加え、pHを8程度に維持しながら晶析を行った。
次に、晶析させた共沈物をろ過、水洗、乾燥、粉砕してFe-Ti共沈物を得た。
次に、Fe-Ti共沈物5.2gに3.8M水酸化リチウム水溶液を40g加え、10分撹拌しスラリーを作製した。その後、スラリーをテフロン(登録商標)容器に入れ蓋をした後、マイクロ波合成装置(マイルストーンゼネラル株式会社)を用いて、出力500W、温度200℃、昇温時間20分、保持時間30分の条件で加熱を行い、鉄含有チタン酸リチウムを合成した。
最後に、炭素質材料としてケッチェンブラック(ライオン株式会社製 EC600JD)を鉄含有チタン酸リチウムに対し、2wt%となるように加え、遊星ボールミルを用い、回転数300rpm、処理時間30分の条件でメカノケミカル処理を行うことによって、実施例25のリチウム二次電池用正極活物質を作製した。
Fe源を塩化鉄(III)(FeCl3)に変更する以外は実施例25と同様にして、実施例26のリチウム二次電池用正極活物質を作製した。
Fe源を硫酸第一鉄(FeSO4)に変更した以外は実施例25と同様にして、実施例27のリチウム二次電池用正極活物質を作製した。
Ti源を硫酸チタン(Ti(SO4)2)に変更した以外は実施例25と同様にして、実施例28のリチウム二次電池用正極活物質を作製した。
Ti源を四塩化チタン(TiCl4)に変更した以外は実施例25と同様にして、実施例29のリチウム二次電池用正極活物質を作製した。
マイクロ波照射時の保持時間を10分に変更した以外は実施例25と同様にして、実施例30のリチウム二次電池用正極活物質を作製した。
マイクロ波照射時の保持時間を40分に変更した以外は実施例25と同様にして、実施例31のリチウム二次電池用正極活物質を作製した。
マイクロ波照射時の保持時間を60分に変更した以外は実施例25と同様にして、実施例32のリチウム二次電池用正極活物質を作製した。
共沈工程において鉄とチタンのモル比率(Fe/Ti比)が2.3となるように変更した以外は実施例25と同様にして、実施例33のリチウム二次電池用正極活物質を作製した。
共沈工程において鉄とチタンのモル比率(Fe/Ti比)が0.3となるように変更した以外は実施例25と同様にして、実施例34のリチウム二次電池用正極活物質を作製した。
マイクロ波照射時の合成温度を150℃に変更した以外は実施例25と同様にして、実施例35のリチウム二次電池用正極活物質を作製した。
マイクロ波照射時の合成温度を240℃に変更した以外は実施例25と同様にして、実施例36のリチウム二次電池用正極活物質を作製した。
具体的には、結晶子径については、X線回折分析装置(パナリティカル製)を用いて測定した。Li、Ti、Feの含有量については、ICP-AES装置(エスアイアイ・ナノテクノロジー株式会社製)を用いてICP発光分光分析法によって測定した。水分量については、水分分析装置(三菱マテリアル株式会社製)を用いてカールフィッシャー法によって測定した。比表面積については、BET法によって測定した。カーボン量については、CNマクロコーダー(株式会社ジェイ・サイエンス製)を用いて測定した。結果を表3に示す。
また、水分量については、実施例25~36のリチウム二次電池用正極活物質については全て2000ppm以下であった。
さらに、比表面積については、実施例25~36のリチウム二次電池用正極活物質については全て20~150m2/gの範囲内であった。
なお、結晶構造解析の結果、実施例25~36のリチウム二次電池用正極活物質については全て、既知の粉末X線回折データに記載されている立方晶岩塩型構造をもつ
LiTiO2やLiFeO2の単位胞により指数付けすることができた。
また、本発明の正極活物質の製造方法によれば、合成後の鉄含有チタン酸リチウムの表面上に残存する未反応のLi源を削減することができ、リチウム二次電池の正極活物質に使用した際には、保存特性に優れるリチウム二次電池を得ることができることがわかった。また、かかる正極活物質を極めて短時間で、かつ低コストで得ることができるとがわかった。
Claims (15)
- 立方晶岩塩型構造であって組成式Li1+x(Ti1-yFey)1-xO2(0<x≦0.3、0<y≦0.8)で表される鉄含有チタン酸リチウムと、
炭素質材料とを含み、
前記鉄含有チタン酸リチウムと前記炭素質材料とはメカノケミカル処理によって複合化されていることを特徴とするリチウム二次電池用正極活物質。
- 前記炭素質材料を0.5~10wt%含むことを特徴とする請求項1に記載のリチウム二次電池用正極活物質。
- 前記鉄含有チタン酸リチウムの結晶子径が5~100nmであることを特徴とする請求項1または請求項2に記載のリチウム二次電池用正極活物質。
- 水分量が2000ppm以下であることを特徴とする請求項1から請求項3のいずれか一項に記載のリチウム二次電池用正極活物質。
- BET法による比表面積が20~150m2/gであることを特徴とする請求項1から請求項4のいずれか一項に記載のリチウム二次電池用正極活物質。
- 下式から算出される電圧降下率が、
5%以下であることを特徴とする請求項1から請求項5のいずれか一項に記載のリチウム二次電池用正極活物質。
(電圧降下率)=((充電直後の電圧-30日保存後測定時電圧)/(充電直後の電圧))×100(%)
- Fe源とTi源とを含む溶液をアルカリ性溶液で中和し、水洗し、乾燥させてFe-Ti共沈物を得る共沈工程と、
前記共沈物をLi源と混合して混合物を得る混合工程と、
前記混合物を焼成して焼成物を得る焼成工程と、
前記焼成物と炭素質材料とをメカノケミカル処理によって複合化させる複合化工程とを含むことを特徴とする請求項1から請求項6のいずれか一項に記載のリチウム二次電池用正極活物質の製造方法。
- 前記焼成工程は不活性ガス雰囲気下において行われることを特徴とする請求項7に記載のリチウム二次電池用正極活物質の製造方法。
- 前記焼成工程は400℃以上700℃以下の温度において行われることを特徴とする請求項7または請求項8に記載のリチウム二次電池用正極活物質の製造方法。
- Fe源とTi源とを含む溶液をアルカリ性溶液で中和し、水洗し、乾燥させてFe-Ti共沈物を得る共沈工程と、
前記共沈物をLi源と混合して混合物を得る混合工程と、
前記混合物にマイクロ波を照射して鉄含有チタン酸リチウムを合成する合成工程と、
前記鉄含有チタン酸リチウムと炭素質材料とをメカノケミカル処理によって複合化させる複合化工程とを含むことを特徴とする請求項1から請求項6のいずれか一項に記載のリチウム二次電池用正極活物質の製造方法。
- 前記合成工程は100℃以上250℃以下の温度において行われることを特徴とする請求項10に記載のリチウム二次電池用正極活物質の製造方法。
- 前記Fe源は、Fe2(SO4)3、FeSO4、FeCl3、Fe(NO3)3のいずれか1つ以上であることを特徴とする請求項7から請求項11のいずれか一項に記載のリチウム二次電池用正極活物質の製造方法。
- 前記Ti源は、Ti(SO4)2、TiOSO4、TiCl4のいずれか1つ以上であることを特徴とする請求項7から請求項11のいずれか一項に記載のリチウム二次電池用正極活物質の製造方法。
- 集電体表面に請求項1から請求項6のいずれか一項に記載のリチウム二次電池用正極活物質からなる層を有することを特徴とするリチウム二次電池用正極。
- 請求項14に記載のリチウム二次電池用正極を備えることを特徴とするリチウム二次電池。
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US12024440B2 (en) | 2017-08-23 | 2024-07-02 | Topsoe Battery Materials A/S | Introduction of titanium homogeneously into a solid material |
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Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2002068748A (ja) * | 2000-08-31 | 2002-03-08 | National Institute Of Advanced Industrial & Technology | 単相リチウムフェライト系複合酸化物 |
JP2002510594A (ja) * | 1998-04-07 | 2002-04-09 | リーデル−デ・ヘン・ゲゼルシャフト・ミト・ベシュレンクテル・ハフツング | リチウム金属酸化物の製造方法 |
JP2005063673A (ja) * | 2003-08-08 | 2005-03-10 | Sanyo Electric Co Ltd | 非水電解質二次電池 |
JP2009158239A (ja) * | 2007-12-26 | 2009-07-16 | Hitachi Vehicle Energy Ltd | リチウム二次電池 |
JP2012030988A (ja) * | 2010-07-28 | 2012-02-16 | Tayca Corp | 鉄含有チタン酸リチウムの製造方法 |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101172646A (zh) * | 2007-11-05 | 2008-05-07 | 桂林工学院 | 一种尖晶石结构钛酸锂的制备方法 |
CN102414880B (zh) * | 2009-07-31 | 2015-05-13 | 株式会社东芝 | 非水电解质电池、用于该非水电解质电池的活性物质、其制造方法、钛酸碱金属化合物的制造方法以及电池包 |
JP5590521B2 (ja) | 2009-11-06 | 2014-09-17 | 独立行政法人産業技術総合研究所 | リチウム二次電池用正極活物質及びその製造方法 |
CN102055020A (zh) * | 2010-07-22 | 2011-05-11 | 中信国安盟固利动力科技有限公司 | 解决以钛酸锂为负极的动力锂离子电池胀气问题的方法 |
CN102185139B (zh) * | 2011-03-31 | 2014-06-04 | 中国科学院过程工程研究所 | 一种纳米金属氧化物/石墨烯掺杂磷酸铁锂电极材料的制备方法 |
CN103123968B (zh) * | 2013-01-29 | 2015-08-19 | 中国科学院过程工程研究所 | 一种高性能磷酸铁锂正极材料及其制备方法 |
-
2013
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Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2002510594A (ja) * | 1998-04-07 | 2002-04-09 | リーデル−デ・ヘン・ゲゼルシャフト・ミト・ベシュレンクテル・ハフツング | リチウム金属酸化物の製造方法 |
JP2002068748A (ja) * | 2000-08-31 | 2002-03-08 | National Institute Of Advanced Industrial & Technology | 単相リチウムフェライト系複合酸化物 |
JP2005063673A (ja) * | 2003-08-08 | 2005-03-10 | Sanyo Electric Co Ltd | 非水電解質二次電池 |
JP2009158239A (ja) * | 2007-12-26 | 2009-07-16 | Hitachi Vehicle Energy Ltd | リチウム二次電池 |
JP2012030988A (ja) * | 2010-07-28 | 2012-02-16 | Tayca Corp | 鉄含有チタン酸リチウムの製造方法 |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2015005444A (ja) * | 2013-06-21 | 2015-01-08 | 太平洋セメント株式会社 | チタン酸リチウム負極活物質 |
JP2020167187A (ja) * | 2019-03-28 | 2020-10-08 | テイカ株式会社 | 蓄電デバイス用プリドープ剤及びその製造方法 |
JP7317542B2 (ja) | 2019-03-28 | 2023-07-31 | テイカ株式会社 | 蓄電デバイス用プリドープ剤及びその製造方法 |
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