WO2001078168A1 - Positive electrode material for lithium secondary cell and lithium secondary cell using the same - Google Patents

Positive electrode material for lithium secondary cell and lithium secondary cell using the same Download PDF

Info

Publication number
WO2001078168A1
WO2001078168A1 PCT/JP2001/001254 JP0101254W WO0178168A1 WO 2001078168 A1 WO2001078168 A1 WO 2001078168A1 JP 0101254 W JP0101254 W JP 0101254W WO 0178168 A1 WO0178168 A1 WO 0178168A1
Authority
WO
WIPO (PCT)
Prior art keywords
lithium
lithium secondary
positive electrode
manganese
less
Prior art date
Application number
PCT/JP2001/001254
Other languages
French (fr)
Japanese (ja)
Inventor
Tuyoshi Kinoshita
Keigi Suzuki
Ryuichi Nagase
Original Assignee
Japan Energy Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Japan Energy Corporation filed Critical Japan Energy Corporation
Publication of WO2001078168A1 publication Critical patent/WO2001078168A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/485—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
    • 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 material for a lithium secondary battery having excellent high-temperature characteristics (high-temperature holding characteristics and high-temperature cycle characteristics) and excellent coating properties. It also relates to a lithium secondary battery having excellent battery characteristics.
  • the “lithium secondary battery” has a higher energy density compared to “Nikkol-dominium batteries” and “nickel-metal hydride batteries” and can further reduce the weight and extend the life of equipment. Is spreading rapidly.
  • this lithium secondary battery is formed by three basic elements: a “positive electrode”, a “negative electrode”, and an “electrolyte-retaining separator" interposed between the two electrodes.
  • the positive electrode and the negative electrode use a “slurry obtained by mixing and dispersing an active material, a conductive material, a binder, and, if necessary, a dispersant in a dispersion medium” to collect current such as a metal foil or a metal mesh. What is applied to the body is used.
  • lithium and cobalt complex oxide (UCoO,) have been mainly used.
  • the negative electrode active material a material capable of inserting and extracting lithium ions (for example, a carbon material such as coke-based carbon and graphite-based carbon) is used.
  • a carbon material such as coke-based carbon and graphite-based carbon
  • the conductive material a substance having electronic conductivity (eg, natural graphite, carbohydrate) Black, acetylene black, etc.), and fluorocarbon resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and hexafluoropropylene (HFP) as binders. These copolymers are used.
  • an organic solvent capable of dissolving the binder such as acetate, methylethylketone (MEK), tetrahydrofuran (THF), dimethylformamide, and dimethylacetamide , Tetramethylurea, trimethyl phosphate, N-methyl-2-pyrrolidone (NMP) and the like are used.
  • an organic solvent that can be replaced with an electrolyte after the slurry is applied to the current collector and formed into a film is appropriate.
  • an “organic solvent” that can be replaced with an electrolyte after the slurry is applied to the current collector and formed into a film is appropriate.
  • An “organic solvent” that can be replaced with an electrolyte after the slurry is applied to the current collector and formed into a film is appropriate.
  • An “organic solvent” that can be replaced with an electrolyte after the slurry is applied to the current collector and formed into a film is appropriate.
  • kind is preferred.
  • stainless steel, nickel, aluminum, titanium, copper perforated metal, and expanded metal are preferred, and these have been subjected to surface treatment. Materials can also be used.
  • the slurry required for coating is adjusted by kneading the above-mentioned active material, conductive material, binder, dispersion medium and plasticizer in a predetermined ratio.
  • Various coating methods such as gravure coating, blade coating, comma coating, and dip coating can be applied to the coating on the current collector.
  • liquid, polymer or solid electrolytes are known as electrolytes to be retained in the separator, but they are composed of a solvent and a lithium salt dissolved in the solvent.
  • Liquid type is often used.
  • the solvent in this case, polyethylene carbonate, ethylene carbonate, dimethyl sulfoxide, butyl lactone, sulfolane, 1,2-dimethoxy ethane, tetrahydrofuran, and getyl carbonate Bok, Mechiruechiruka Bone DOO, organic solvents such as dimethyl carbonate Natick bets are suitable, in the Matari lithium salt Li CF, S 0 ,, LiAsF LiCI 0 Li BF *, Li PF s And the like are preferred.
  • lithium-nickel composite oxides LiNiO,
  • Lithium 'manganese composite oxide ⁇ Li, + x M - ⁇ 4 (0 ⁇ x ⁇ 0.20) ⁇ has a high discharge voltage and a large interest from thermal stability in a charged state that relatively high I'm getting bathed.
  • Lithium 'manganese composite oxide ⁇ Li i + xMn, - x0 4 (0 ⁇ X ⁇ 0.20) ⁇ is electrolytic manganese dioxide (EMD) or chemical dioxide manganese (CMD) Moshiku is by heat-treating them It is synthesized by mixing the obtained “manganese oxide” such as Mn! 0 ,, ⁇ , ⁇ , etc. and “lithium compound” such as lithium carbonate at a predetermined ratio, and subjecting it to heat treatment.
  • EMD electrolytic manganese dioxide
  • CMD chemical dioxide manganese
  • the present inventors have provided a cathode material exhibiting excellent characteristics (various battery characteristics such as high-temperature cycle characteristics) for a lithium secondary battery, and also used the cathode material with excellent battery characteristics. Research to realize a lithium secondary battery.
  • lithium-manganese composite oxide ⁇ ,, + ⁇ , ,, (0 ⁇ X ⁇ 0.20) ⁇ lithium-manganese composite oxide
  • Lithium for the positive electrode active material is a “lithium manganese composite oxide.”
  • lithium secondary batteries can be used. Characteristics can be improved.
  • lithium-manganese composite oxides which are fine particles with an average particle diameter of 10 ⁇ m or less and whose particle shape is spherical, have been tested in the following series of trials. It was achieved at the end.
  • Electrolytic manganese dioxide EMD
  • CMD chemical manganese dioxide
  • ⁇ ⁇ , ⁇ , ⁇ , ⁇ are considered to have good fluidity and high packing density, but have a large particle size (maximum particle size of 100 m or more, average particle size of 25 or more).
  • maximum particle size 100 m or more, average particle size of 25 or more.
  • the resulting composite oxides also become irregularly shaped particles having a large particle size, and the density is not sufficient, so that satisfactory battery characteristics cannot be exhibited.
  • the final reaction is accelerated, and the final density is high (the density of 1.8 g / cm : can be sufficiently achieved).
  • lithium fine particles having an average particle diameter of 10 m or less and having a spherical particle shape can be realized by a new method.
  • Lithium-manganese composite oxides composed of spherical particles of ⁇ m or less have poor coating properties when applied to a current collector as a positive electrode material for lithium secondary batteries, and electrodes with conventional compositions It is clear that coating irregularities occur frequently when attempting to coat the current collector with a film-forming slurry. I got it.
  • an object of the present invention is to provide a positive electrode material for lithium secondary batteries which is excellent not only in high-temperature characteristics (high-temperature holding characteristics and high-temperature cycle characteristics) but also in coating properties.
  • the aim was to realize a lithium secondary battery that could maintain excellent battery characteristics without being particularly affected by environmental temperature. Disclosure of the invention
  • the present inventors have conducted further research to achieve the above object, and as a result, have obtained the following new knowledge.
  • Lithium as a positive electrode material for lithium secondary batteries ⁇
  • manganese composite oxides require finer particles to improve battery characteristics, coating properties greatly affect their specific surface area, and lithium ⁇ manganese composites. Even if the oxide is very fine particles, if its specific surface area is large, agglomerates will be formed during coating, which tends to cause unevenness, but lithium-manganese composite oxides with a small specific surface area are excellent. Coatability is ensured.
  • the specific surface area of the lithium 'manganese composite oxide is also greatly affected by the characteristics maintenance performance (retention of the positive electrode active material, cycle characteristics) of the lithium secondary battery using the lithium' manganese composite oxide as the cathode material. If the specific surface area is large, the "dissolution of Mn" becomes remarkable when left at high temperature in the charged state, and the retention characteristics and cycle characteristics tend to deteriorate.
  • the present invention has been made based on the above findings and the like, and provides the following positive electrode material for lithium secondary batteries and lithium secondary batteries.
  • the chemical composition consists of an average particle diameter of 1 0 or smaller particles represented by U 4 (0 ⁇ x ⁇ 0.20), and a specific surface area of the feature to be less than 1 m z / g, a lithium secondary Positive electrode material for secondary batteries.
  • a lithium secondary battery characterized in that a material having a specific surface area of not less than 1 ⁇ m and a specific surface area of not more than 1 m 2 / g is applied to a positive electrode material.
  • the present invention provides a method for producing an “average particle size of 10 m or less and a specific surface area of
  • this lithium-manganese composite can be used by using it as a positive electrode material for lithium secondary batteries.
  • a major feature is that the high-temperature characteristics (high-temperature holding characteristics and high-temperature cycle characteristics) of oxide-based lithium secondary batteries can be improved.
  • FIG. 2 is a graph comparing the cycle test results of the lithium batteries produced in the example and the comparative example.
  • FIG. 3 is an electron micrograph (SEM) of the fine-grained lithium-manganese composite oxide obtained in the comparative example.
  • Lithium ⁇ manganese composite oxide according to the present invention Li, + ⁇ ⁇ 1 ⁇ Bok x the value of X in OJ
  • the reason for limiting the "0 ⁇ X ⁇ 0.20" the scan when the value of X is a negative value Pinel structure
  • the discharge capacity when used as the positive electrode active material of a lithium secondary battery becomes 100 mAh / g or less.
  • the average particle size of the lithium-manganese composite oxide ⁇ Li, + ⁇ ⁇ 2 ⁇ (, (0 ⁇ X ⁇ 0.20) ⁇ is less than 10 m.
  • the specific surface area is 1 m 2 / g or less
  • the specific surface area exceeds 1 m 2 / g, this is The coating properties of the positive electrode material when applied to the current collector are worse than those with a small specific surface area. This is because the frequency of the generation of coating unevenness increases and the product quality tends to become unstable.
  • the lithium-manganese composite oxide also has a positive effect on lithium secondary battery characteristics maintenance performance (retention and cycling characteristics of the positive electrode active material).
  • the ratio If the surface area is greater than 1 m '/ g, "leaching of Mn" becomes remarkable when left at high temperature in a charged state, and the retention characteristics and cycle characteristics tend to deteriorate.
  • the process of producing lithium ⁇ manganese composite oxide by the reaction between manganese oxide and lithium compound extremely fine primary particles of lithium 'manganese composite oxide are generated, and then these primary particles are mutually bonded. It is considered that the secondary abscission is formed and the reaction is completed by the parallel progress of the bonding and the nucleation and grain growth. Therefore, when observing the obtained lithium-manganese composite oxide particles, it is recognized that the primary particles of the fine particles adhere to the surface of the large-grown secondary particles to form an integrated structure.
  • the composition, particle size, and specific surface area of the lithium-manganese composite oxide greatly affect the characteristics as a positive electrode material for a lithium secondary battery.
  • the particle size of the above primary particles (observed as fine particles attached to the surface of the grown secondary particles) in the composite oxide also increases through the specific surface area of the lithium-manganese composite as a positive electrode material for lithium secondary batteries. It has also been found that lithium ⁇ manganese composite oxides, in which the primary particles have a particle size of 1 am or more, are preferable in terms of coatability and battery characteristics.
  • Lithium-manganese composite oxide with an average particle size of 10 m or less and a specific surface area of 1 m '/ g or less ⁇ Li, + x Mn 2 — x O 4 (0 ⁇ x ⁇ 0.20) ⁇ "
  • Particle size is 1 or more lithium ⁇ manganese composite oxide has an average particle diameter of 10 ⁇ m or less manganese oxide (Nln0 2, Mn 2 0! Or Mn 3 0 4) and Lithium compound (carbonate Lithium etc. ) Can be manufactured by mixing and firing at a predetermined ratio, but it is important to carefully select the firing reaction raw materials through preliminary tests.
  • the firing temperature in this case is suitably in the range of 450 to 900 ° C.
  • the desired fine particle lithium ⁇ manganese composite oxide ⁇ Li, + ⁇ ⁇ ⁇ ⁇ ⁇ , (0 ⁇ x ⁇ 0.20) ⁇ in order to obtain the tap density as the oxidizing manganese is preferably calcined material 1.8 It is preferable to use those having a g / cm 5 or more, more preferably those having a spherical particle shape.
  • Manganese oxide as sintering raw material (Mn0 2, Mn z 0 5 , n, 0 4) is a fine ⁇ manganese can be made viable by heat treatment at in air 3 0 0 ° C or higher,
  • a more preferable manganese oxide raw material is to heat-treat manganese carbonate having a spherical particle shape in an atmosphere having an oxygen concentration of less than 15% (preferably in a nitrogen atmosphere) at a high temperature of 600 to 900 ° C.
  • second heat treatment at a lower temperature of 530 to 800 ° C in an atmosphere with an oxygen concentration of 15% or more.
  • This treatment method obtains fine particles Mn, 0, which are suitable for the production of lithium manganese composite oxides having a small specific surface area and a small specific surface area, and porous MnO 2 is generated by the first stage heat treatment.
  • manganese oxides of low oxidation state is generated without, this atmosphere of oxygen concentration when is generated MnO z multi porous and is 1 5% or more, preferably lithium ⁇ manganese composite oxide synthesis Hara There is no charge. If the heat treatment temperature at this time is lower than 600 ° C., a manganese oxide in a low oxidation state cannot be obtained effectively. When the temperature exceeds ° C, the formed manganese oxide is remarkably agglomerated and irregular particles increase, so that fine manganese oxide suitable as a raw material for lithium and manganese composite oxides for lithium secondary batteries cannot be obtained.
  • manganese oxide with a high density is generated, but it takes a long time to form ⁇ , ,, and a single phase at low oxygen concentration.
  • the second-stage heat treatment is performed to shorten the time Mns C converts Mn z O, the. If the treatment temperature in the second stage heat treatment is lower than 530 ° C or the oxygen concentration in the heat treatment atmosphere is lower than 15%, ⁇ ⁇ , ⁇ , contained ⁇ ⁇ , ⁇ , It may not be converted quickly to a long time, and it may take a long time to process or deteriorate the performance of the product.
  • the treatment temperature in the second stage heat treatment is greater than 8 0 0 ° C
  • manganese oxide high evening-up density can not be obtained by also obtained oxide agglutination significantly Do connexion fine manganese (here
  • the switching of the heat treatment temperature for converting ⁇ ⁇ , ⁇ , to ⁇ ⁇ ⁇ , ⁇ , may be performed at the same time as the generation of manganese oxide in a low oxidation state, and the oxygen concentration in the heat treatment atmosphere is not less than 15%. need not be a time of enhanced.
  • carbonated manganese raw material spherical applied to the method for producing manganese oxide are "manganese sulfate solution and bicarbonate Anmoniumu also is properly bicarbonate Na dissolved bets method of mixing Li um "and" Anmoniu ⁇ solution manganese metal containing ions, a method for venting a C 0 2 gas after a predetermined manganese concentration (No. 3 0 3 2 9 7 5 No.)) Can be built.
  • the chemical composition is Li, + x Mn 2 -x O, (0 ⁇ X ⁇ 0.20), the average particle size is 10; the particles are less than m, and the specific surface area is 1 m '/ g or less. Or lithium whose primary particles have a particle size of 1 m or more.
  • lithium-manganese composite oxide it is possible to realize a relatively inexpensive lithium secondary battery having excellent battery characteristics including the characteristic maintenance performance.
  • spherical manganese carbonate having an average particle size of 6.9 m was produced by dissolving metallic manganese in ammonium sulfate and introducing carbon dioxide gas into the solution to precipitate manganese carbonate.
  • the obtained manganese carbonate was used as a starting material, and this was subjected to a heat treatment at 800 ° C. for 1 hour in nitrogen, and oxygen was subsequently introduced into the atmosphere to reduce the oxygen concentration in the atmosphere to 20%. %, And heat treatment was further performed at 65 ° C. for 1 hour in this atmosphere to obtain ⁇ , ⁇ with an average particle size of 7 ⁇ m. After mixing 12 g of the fine particles ⁇ : 0, with 3.17 g of lithium carbonate, the mixture was fired in air at 750 ° C. for 10 hours.
  • the obtained powder of the compound was measured powder X-ray diffraction, Li, + x Mn 2 - was confirmed to be x O ⁇ single phase (0 ⁇ x ⁇ 0.20).
  • the lithium-manganese composite oxide (Li i + xMn! X O, (0 ⁇ X ⁇
  • the applicability was evaluated using the obtained lithium ⁇ manganese composite oxide as the positive electrode active material at 85 wt%, polyvinylidene fluoride as the binder 7 wt%, and acetylene black as the conductive material 8 wt%. It was weighed and added with acetone as a dispersion medium to form a slurry, which was then applied to an aluminum foil with a hand and iron to observe the applied state. As a result, a coating film having a uniform thickness was formed without generation of coating streaks, and it was confirmed that the positive electrode material of the present invention had excellent coatability.
  • the amount of Mn eluted was investigated by a method of measuring the amount of Mn eluted by inductively coupled plasma (ICP) after immersing the lithium-manganese composite oxide in an electrolyte solution at 55 ° C for 1 week.
  • ICP inductively coupled plasma
  • the measured amount of Mn eluted was 0.3 mg per 1 g of lithium ⁇ manganese composite oxide, which is remarkably improved compared to about 1 mg per 1 g of lithium ⁇ manganese composite oxide of the conventional material. It was confirmed that in the cathode material of the present invention, deterioration of high-temperature characteristics (elution of Mn into the electrolyte at a high temperature), which is the most concerned about Mn-based cathode materials, was remarkably suppressed.
  • lithium secondary batteries using the obtained lithium-manganese composite oxide as the positive electrode active material were also investigated.
  • the obtained lithium ⁇ manganese composite oxide 85% by weight of ⁇ Li ,, (0 ⁇ x ⁇ 0.20) ⁇ as active material, 8% by weight of acetylene black as conductive material, and 7 v »t% of polyvinylidene fluoride as binder Each was weighed, and acetonitrile was added as a dispersion medium to form a slurry. The slurry was applied on an aluminum foil, and then the solvent was evaporated to prepare a positive electrode of a lithium battery.
  • the lithium battery that satisfies the specified conditions of the present invention using lithium-manganese composite oxide as the positive electrode active material has high cycle characteristics at high temperature (55 ° C). It is clear that it is excellent, and it can also be confirmed that it has excellent retention characteristics in combination with the result of the above-mentioned Mn elution amount investigation.
  • the spherical fine-grained manganese carbonate having an average particle size of 6.9 m produced in the above example was used as a starting material, and this was subjected to a heat treatment at 650 X) in nitrogen for 1 hour, and subsequently into an atmosphere. Oxygen was introduced to change the oxygen concentration in the atmosphere to 20%, and heat treatment was further performed in the atmosphere at the same temperature of 65 ° C. for 1 hour to obtain Mn 20 , having an average particle size of 7 ⁇ m. Obtained.
  • the powder of the obtained compound was subjected to powder X-ray diffraction measurement. As a result, it was confirmed that L + ⁇ ⁇ ⁇ 2 - ⁇ , was a single phase (0 ⁇ x ⁇ 0.20).
  • the particle size of the primary particles was found to be less than 1 ⁇ m.
  • FIG. 3 is a SEM photograph of the lithium-manganese composite oxide obtained by this comparative example.
  • the coating properties were not sufficient, such as streaks in the coating film due to agglomerated particles during coating, and it was evaluated that there were difficulties in stably producing a coating film having a uniform thickness.
  • This low evaluation of the coating property is considered to be due to the formation of aggregated particles due to the large specific surface area of the lithium-manganese composite oxide.
  • the amount of Mn eluted at a high temperature in the obtained lithium-manganese composite oxide was measured by the same method as in the above-mentioned Example.
  • the measured elution amount of Mn was 0.7 mg per 1 g of lithium ⁇ manganese composite oxide, deteriorating the high-temperature characteristics of Mn-based cathode materials (Mn elution into electrolyte at high temperatures) was found to occur.
  • a lithium cell a lithium battery
  • a coin cell CR2032
  • the lithium secondary battery using the lithium ⁇ manganese composite oxide obtained in this comparative example as a positive electrode active material also has a specific surface area in terms of high-temperature retention characteristics. It is evident that it will be inferior to those using a lithium manganese composite oxide of 1 m 2 / g or less as the positive electrode active material.
  • the present invention it is possible to provide a cathode material for a lithium secondary battery having excellent coatability and excellent high-temperature characteristics, and realize a relatively inexpensive lithium secondary battery having excellent battery characteristics. It has an extremely useful effect on industry, such as enabling

Abstract

A positive electrode material for a lithium secondary cell, characterized in that it comprises particles having a chemical composition represented by Li1+xMn2-xO4 (0 ≤ x ≤ 0.20) and having an average particle diameter of 10 νm or less and a specific surface area of 1 m2/g or less; or in that it comprises particles which have, in addition to the above, a diameter of primary particles constituting the above particles of 1 νm or more; and a lithium secondary cell using the positive electrode material. The positive electrode material is excellent not only in high temperature characteristics, but also in applicability, and thus can be used for producing a lithium secondary cell which is able to keep excellent cell characteristics without being significantly affected by ambient temperature.

Description

明 細 書 リチウムニ次電池用正極材料及びそれを用いたリチウムニ次電池  Description Positive electrode material for lithium secondary battery and lithium secondary battery using the same
技術分野 Technical field
この発明は、 優れた高温特性 （高温保持特性， 高温サイクル特性） を 有すると共に塗工性にも優れたリチウム二次電池用正極材料に関し、 更 には該材料を正極活物質としたところの高温での電池特性に優れるリチ ゥ厶二次電池にも関わるものである。  The present invention relates to a positive electrode material for a lithium secondary battery having excellent high-temperature characteristics (high-temperature holding characteristics and high-temperature cycle characteristics) and excellent coating properties. It also relates to a lithium secondary battery having excellent battery characteristics.
背景技術 Background art
近年、 "二ッケルー力 ドミゥ厶電池" や "ニッケル—水素電池" 等に 比べると高いエネルギー密度を有していて機器の更なる軽量化や高寿命 化が図れることから、 "リチウム二次電池" の普及が急速な伸びを見せ ている。  In recent years, the “lithium secondary battery” has a higher energy density compared to “Nikkol-dominium batteries” and “nickel-metal hydride batteries” and can further reduce the weight and extend the life of equipment. Is spreading rapidly.
周知のように、 このリチウム二次電池は "正極"， "負極" 及び両電極 間に介在せしめられる "電解質を保持したセパレー夕 " の 3つの基本要 素によって搆成されている。  As is well known, this lithium secondary battery is formed by three basic elements: a "positive electrode", a "negative electrode", and an "electrolyte-retaining separator" interposed between the two electrodes.
このうち、 正極及び負極には、 "活物質， 導電材， 結着材及び必要に 応じて可塑剤をも分散媒に混合分散させて成るスラリー " を金属箔， 金 属メ ッシュ等の集電体に塗工したものが使用される。  Among these, the positive electrode and the negative electrode use a “slurry obtained by mixing and dispersing an active material, a conductive material, a binder, and, if necessary, a dispersant in a dispersion medium” to collect current such as a metal foil or a metal mesh. What is applied to the body is used.
ここで、 正極活物質としては、 従前からリチウム ， コバル卜複合酸化 物 （U Co O , ) が主に用いられている。  Here, as the positive electrode active material, lithium and cobalt complex oxide (UCoO,) have been mainly used.
また、 負極活物質としては、 リチウムイオンを吸蔵■放出できる物質 (例えばコークス系炭素や黒鉛系炭素等の炭素材料） が適用される。 導電材としては、 電子伝導性を有する物質 （例えば天然黒鉛， カーボ ンブラッ ク， アセチレンブラック等） が用いられ、 結着材と してはポリ テ トラフル才ロエチレン （ P T F E ) ， ポリ フッ化ビニリ デン （ P V D F ) , へキサフロロプロ ピレン （ H F P ) 等のフ ッ素系樹脂やこれらの 共重合体等用いられている。 As the negative electrode active material, a material capable of inserting and extracting lithium ions (for example, a carbon material such as coke-based carbon and graphite-based carbon) is used. As the conductive material, a substance having electronic conductivity (eg, natural graphite, carbohydrate) Black, acetylene black, etc.), and fluorocarbon resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and hexafluoropropylene (HFP) as binders. These copolymers are used.
分散媒と しては、 結着材を溶解することが可能な有機溶媒、 例えばァ セ ト ン， メチルェチルケ ト ン（M E K ) ， テ トラ ヒ ドロフラン（T H F ), ジメチルホルムアミ ド， ジメチルァセ夕ミ ド， テ 卜ラメチル尿素， リ ン 酸 卜 リメチル， N—メチル一 2 —ピロ リ ドン（ N M P )等が用いられる。 必要に応じて加えられる可塑剤と しては、 スラ リ 一が集電体に塗工さ れ成膜された後に電解液との置換が可能な "有機溶媒" が適切で、 フタ ル酸ジエステル類が好ま しい。  As the dispersion medium, an organic solvent capable of dissolving the binder, such as acetate, methylethylketone (MEK), tetrahydrofuran (THF), dimethylformamide, and dimethylacetamide , Tetramethylurea, trimethyl phosphate, N-methyl-2-pyrrolidone (NMP) and the like are used. As an optional plasticizer, an “organic solvent” that can be replaced with an electrolyte after the slurry is applied to the current collector and formed into a film is appropriate. Kind is preferred.
スラ リ ーが塗工される集電体と しては、 ステンレス鋼， ニッケル， ァ ルミ二ゥム， チタ ン， 銅のパンチングメタル， エキスパン ドメタルが好 ま しく、 これらに表面処理を施した材料も使用できる。  As the current collector on which the slurry is applied, stainless steel, nickel, aluminum, titanium, copper perforated metal, and expanded metal are preferred, and these have been subjected to surface treatment. Materials can also be used.
そして、 塗工に必要なスラ リ ーは、 上記活物質， 導電材， 結着材， 分 散媒及び可塑剤を所定の比率で混練して調整される。 また、 集電体への 塗工には、 グラ ビアコー ト， ブレー ドコ一 ト， コ ンマコー ト， ディ ップ コ ー 卜等の各種塗工方法を適用することができる。  The slurry required for coating is adjusted by kneading the above-mentioned active material, conductive material, binder, dispersion medium and plasticizer in a predetermined ratio. Various coating methods such as gravure coating, blade coating, comma coating, and dip coating can be applied to the coating on the current collector.
—方、 セパレー夕に保持させる電解質と しては液体系， ポリ マー系あ るいは固体系のものが知られているが、 溶媒とその溶媒に溶解する リ チ ゥム塩とから構成される液体系のものが良く 用いられている。 この場合 の溶媒と しては、 ポリエチレンカーボネ一 卜， エチレンカーボネ一 卜， ジメチルスルホキシ ド， プチルラク ト ン， スルホラン， 1,2-ジメ トキシ ェタン， テ 卜ラ ヒ ドロフラン， ジェチルカーボネー 卜， メチルェチルカ ーボネー ト， ジメチルカーボネー ト等の有機溶媒が適当であり、 またリ チウム塩と しては Li C F ,S 0 ,， LiAsF LiCI 0 Li B F *， Li P F s 等が好ましいとされている。 On the other hand, liquid, polymer or solid electrolytes are known as electrolytes to be retained in the separator, but they are composed of a solvent and a lithium salt dissolved in the solvent. Liquid type is often used. As the solvent in this case, polyethylene carbonate, ethylene carbonate, dimethyl sulfoxide, butyl lactone, sulfolane, 1,2-dimethoxy ethane, tetrahydrofuran, and getyl carbonate Bok, Mechiruechiruka Bone DOO, organic solvents such as dimethyl carbonate Natick bets are suitable, in the Matari lithium salt Li CF, S 0 ,, LiAsF LiCI 0 Li BF *, Li PF s And the like are preferred.
ところが、 最近になって正極活物質の原料である "コバルト （Co) " が資源に限りのあることや高価であることが問題視されるようになり、 リ チウム ■ コバル卜複合酸化物 (LiCoO ) に代わるリ チウム電池用正 極活物質としてリ チウム ' マンガン複合酸化物 {U 4 (0≤ XHowever, recently, it has become a problem that “Cobalt (Co)”, which is the raw material of the positive electrode active material, has limited resources and is expensive, and lithium ■ cobalt composite oxide (LiCoO) ) As a positive electrode active material for lithium batteries as lithium-manganese composite oxide (U 4 (0≤ X
≤0.20) } やリチウム ■ ニッケル複合酸化物 （LiNiO , ) が検討される ようになつてきた。 ≤0.20)} and lithium-nickel composite oxides (LiNiO,) have begun to be considered.
これらの中でも、 リ チウム ' マンガン複合酸化物 {Li , + xM — χθ 4 (0≤ x≤0.20) } は放電電圧が高く、 また充電状態の熱的安定性が比較 的高いことから大きな注目を浴びるようになつている。 Among these, Lithium 'manganese composite oxide {Li, + x M - χθ 4 (0≤ x≤0.20)} has a high discharge voltage and a large interest from thermal stability in a charged state that relatively high I'm getting bathed.
一般に、 リ チウム ' マンガン複合酸化物 {Li i + xMn,— x04 (0≤ X ≤ 0.20) } は、 電解二酸化マンガン （ E M D ) あるいは化学二酸化マンガ ン （C M D) もしく はこれらを熱処理して得られた Mn! 0 ,， Μη,Ο 等 の "酸化マンガン" と炭酸リチウム等の "リチウム化合物" とを所定の 割合で混合し、 それを熱処理することによって合成されている。 Generally, Lithium 'manganese composite oxide {Li i + xMn, - x0 4 (0≤ X ≤ 0.20)} is electrolytic manganese dioxide (EMD) or chemical dioxide manganese (CMD) Moshiku is by heat-treating them It is synthesized by mixing the obtained "manganese oxide" such as Mn! 0 ,, Μη, と, etc. and "lithium compound" such as lithium carbonate at a predetermined ratio, and subjecting it to heat treatment.
しかしながら、 このようにして合成された従前のリチウム ■ マンガン 複合酸化物では、 これをリチウムニ次電池の正極活物質として用いた場 合には電池のサイクル特性 （特に高温でのサイクル特性） が十分とはな らず、 これが実用上の大きな問題となっている。  However, with the conventional lithium-manganese composite oxide synthesized in this way, when this is used as a positive electrode active material of a lithium secondary battery, the cycle characteristics of the battery (particularly at high temperatures) are not sufficient. However, this is a major practical problem.
そこで、 本発明者等は、 リチウム二次電池用と して優れた特性 （高温 でのサイクル特性を始めとした諸電池特性） を示す正極材料を提供する と共に、 これを用いて電池特性の優れたリチウムニ次電池を実現すべく 研究を開始した。  Therefore, the present inventors have provided a cathode material exhibiting excellent characteristics (various battery characteristics such as high-temperature cycle characteristics) for a lithium secondary battery, and also used the cathode material with excellent battery characteristics. Research to realize a lithium secondary battery.
そして、 ます、 「リチウム ' マンガン複合酸化物 {ϋ , + χΜη, χΟ , (0≤ X ≤0.20) } をリチウム二次電池用正極材料として適用した場合の サイクル特性は、 リ チウム ' マンガン複合酸化物の粒径と形状に大きく 依存しており、 正極活物質用リチウム " マンガン複合酸化物として "平 均粒径が 1 0 m以下の微細粒であってかつその粒子形状が球形のもの を適用することによってリチウ厶二次電池の特性改善が可能となる」 と の知見を得た。 Furthermore, the cycle characteristics of the lithium-manganese composite oxide {,, + χΜη, ,, (0≤X≤0.20)} as lithium-manganese composite oxide Larger particle size and shape Lithium for the positive electrode active material is a “lithium manganese composite oxide.” By using fine particles with an average particle diameter of 10 m or less and having a spherical particle shape, lithium secondary batteries can be used. Characteristics can be improved. "
なお、 このような "平均粒径が 1 0 〃 m以下の微細粒であってかつそ の粒子形状が球形のリチウム ■ マンガン複合酸化物'' は、 次のような一 連の試行 '検討の末に実現することができたものである。  Such lithium-manganese composite oxides, which are fine particles with an average particle diameter of 10 μm or less and whose particle shape is spherical, have been tested in the following series of trials. It was achieved at the end.
a) 従前からリチウム ' マンガン複合酸化物の製造用原料として用い られてきた前記電解二酸化マンガン（ E M D ) や化学二酸化マンガン（ C M D ) あるいはこれらを熱処理して得られる Μη,Ο ,， Μη,Ο ,等は、 流動 性が良好で充塡密度が高いとされてはいるものの、 粒子径が大きく （最 大粒径 1 0 0 m以上， 平均粒径 2 5 以上） 、 このように大きな粒 怪を持つ材料を原料としてリチウム ■ マンガン複合酸化物を合成すると, 得られる複合酸化物も粒径が大きい不定形粒子となり、 夕ップ密度も十 分でなくて満足できる電池特性が発揮されない。  a) Electrolytic manganese dioxide (EMD) or chemical manganese dioxide (CMD), which has been used as a raw material for the production of lithium manganese composite oxides, or 熱処理 η, Ο ,, Μη, Ο, Are considered to have good fluidity and high packing density, but have a large particle size (maximum particle size of 100 m or more, average particle size of 25 or more). When lithium ■ manganese composite oxides are synthesized using the raw materials as the raw materials, the resulting composite oxides also become irregularly shaped particles having a large particle size, and the density is not sufficient, so that satisfactory battery characteristics cannot be exhibited.
b) なお、 これらの酸化マンガンを粉砕して粒径を小さくすることに より リチゥ厶二次電池用としての特性を改善させることも考えられるが, これら酸化マンガンは元々構造が多孔質であるので粉砕して粒径が小さ くなるとタツプ密度が著しく小さくなり （1.5g/cm'を大きく下回ってし まう） 、 電池特性が悪くなる。  b) It is also conceivable to improve the characteristics for lithium secondary batteries by grinding these manganese oxides to reduce the particle size.However, since these manganese oxides are originally porous, their structure is porous. When the particle size is reduced by pulverization, the tap density becomes extremely low (it is much lower than 1.5 g / cm '), and the battery characteristics deteriorate.
c) ところが、 最近、 微細粒炭酸マンガンの製造に関する検討が多く 行われるようになり、 本発明者等も 「メ ジアン径が 5 mを下回る微細 粒炭酸マンガンの工業的製造方法」 を確立したが （特許第 3 0 3 2 9 7 5号） 、 このような微細粒炭酸マンガン （MnC O , ) を空気中で加熱処 理すると、 平均粒径が 1 0 m以下の微細な酸化マンガンを得ることが できる （なお、 特許第 3 0 3 2 9 7 5号に係る微細粒炭酸マンガンの製 造方法は、 二価のマンガンィ才ンと炭酸ィ才ンあるいは炭酸水素ィ才ン とをアンモニア水の共存下で反応させることを特徴とするものである）。 c) However, recently, many studies on the production of fine-grained manganese carbonate have been conducted, and the present inventors have established an `` industrial production method of fine-grained manganese carbonate having a median diameter of less than 5 m. '' (Patent No. 3032975) When such fine manganese carbonate (MnCO,) is heated in air, a fine manganese oxide having an average particle size of 10 m or less can be obtained. (Note that the production of fine-grained manganese carbonate according to Patent No. 03329775) is possible. The production method is characterized by reacting divalent manganese and carbonic acid or bicarbonate in the presence of aqueous ammonia.)
d) また、 微細炭酸マンガン （MnC O , ) を出発原料とし、 まず低酸 化雰囲気 （酸素濃度 1 5 %未満の雰囲気） で熱処理すると、  d) Starting from fine manganese carbonate (MnCO,), heat treatment in a low-oxidizing atmosphere (atmosphere with an oxygen concentration of less than 15%)
MnC 05 + X 02 MnC 0 5 + X 0 2
= ( η,Ο 、 又は Μη,Ο , と Μη, Ο , の混合物） + C 0 : なる反応が生じて密度の高い低酸化状態のマンガン酸化物が生成し、 こ れに引き続いて雰囲気を酸化性 （酸素濃度 1 5 %以上の雰囲気） にして 5 3 0 °C以上の温度で熱処理すると、  = (η, Ο, or a mixture of Οη, Ο, and Μη, Ο) + C 0: A reaction takes place to produce dense, low-oxidation manganese oxide, which is subsequently oxidized. Heat (atmosphere with an oxygen concentration of 15% or more) and a heat treatment at a temperature of 530 ° C or more
(Mn,04、 又は Μη,Ο と Mn!O ,の混合物） + y O , = Mn,〇 s (Mn, 0 4, or Μη, Ο and Mn! O, mixture of) + y O, = Mn, 〇 s
なる反応が促進されて、 最終的に夕ップ密度の高い（夕ップ密度 1.8g/cm: 以上も十分に達成できる） 球状で平均粒径が 1 0 m以下の微細粒高密 度酸化マンガン（Μηζ Ο ,)が得られる。 The final reaction is accelerated, and the final density is high (the density of 1.8 g / cm : can be sufficiently achieved). Spherical, high-density manganese oxide with an average particle size of 10 m or less. (Μη ζ Ο,) is obtained.
e) そして、 このようにして得られた微細粒酸化マンガンを原料とし、 これとリチウム化合物とを反応させることにより、 平均粒径が 1 O ^ m 以下の球状リチウム ■ マンガン複合酸化物を得ることができる。  e) Using the fine-grained manganese oxide thus obtained as a raw material and reacting it with a lithium compound, a spherical lithium having an average particle diameter of 1 O ^ m or less can be obtained. Can be.
本発明者等は、 新たな手法により実現することができた上記 「平均粒 径が 1 0 m以下の微細粒であってかつその粒子形状が球形のリチウム The present inventors have found that the above-described “lithium fine particles having an average particle diameter of 10 m or less and having a spherical particle shape can be realized by a new method.
■ マンガン複合酸化物 {Li , + )Jn2 x O 4 (0≤ x ≤0.20) } 」 に関し、 そ の後も、 これをリチウム二次電池の正極材料 （正極活物質） として適用 した場合の特性について多方面からの検討を続けた。 ■ Manganese composite oxide {Li, +) Jn 2 x O 4 (0≤ x ≤0.20)} ”, and when it is applied as a cathode material (cathode active material) for lithium secondary batteries We continued to study the characteristics from various angles.
その結果、 前記の如き新規手法によって得られる 「平均粒径が 1 0 As a result, the “average particle size obtained by the new method
〃 m以下の球形粒子から成るリチウム ' マンガン複合酸化物」 であって も、 これをリチウムニ次電池の正極材料として集電体に塗工する際の塗 ェ性が必ずしも良くなく、 従来組成の電極膜形成スラ リ ーにして集電体 に塗工しょうとすると塗工ムラを発生する頻度の高いことが明らかとな つた。 Lithium-manganese composite oxides composed of spherical particles of 〃 m or less have poor coating properties when applied to a current collector as a positive electrode material for lithium secondary batteries, and electrodes with conventional compositions It is clear that coating irregularities occur frequently when attempting to coat the current collector with a film-forming slurry. I got it.
また、 これを正極材料としたリチウム二次電池は "充電状態で高温に 放置した場合の電池特性（正極活物質材料の保持特性）" が必ずしも良く なく、 この点でも改善する余地のあることが分かつた。  In addition, a lithium secondary battery using this as a positive electrode material does not always have good “battery characteristics when left at high temperature in the charged state (retention characteristics of the positive electrode active material material)”, and there is still room for improvement in this regard. I was separated.
このようなことから、 本発明の目的は、 高温特性 （高温保持特性， 高 温サイクル特性） に優れることは勿論のこと、 塗工性にも優れたリチウ ムニ次電池用正極材料を提供し、 環境温度に格別な影響を受けることな く優れた電池特性を維持し得るリチウムニ次電池を実現することに置か れた。 発明の開示  Accordingly, an object of the present invention is to provide a positive electrode material for lithium secondary batteries which is excellent not only in high-temperature characteristics (high-temperature holding characteristics and high-temperature cycle characteristics) but also in coating properties. The aim was to realize a lithium secondary battery that could maintain excellent battery characteristics without being particularly affected by environmental temperature. Disclosure of the invention
本発明者等は上記目的を達成すベく更に研究を続けた結果、 次のよう な新たな知見を得ることができた。  The present inventors have conducted further research to achieve the above object, and as a result, have obtained the following new knowledge.
A ) リチウ厶二次電池正極材料としてのリ チウム ■ マンガン複合酸化 物の電池特性の向上にはその微粒子化は欠かせないものの、 塗工性 はその比表面積に大きく影響し、 リチウム ■ マンガン複合酸化物が 非常に微細な粒子であったとしてもその比表面積が大きいと塗工の 際に凝集粒が生成してムラを生じがちとなるが、 比表面積の小さい リチウム " マンガン複合酸化物では優れた塗工性が確保される。  A) Lithium as a positive electrode material for lithium secondary batteries ■ Although manganese composite oxides require finer particles to improve battery characteristics, coating properties greatly affect their specific surface area, and lithium ■ manganese composites. Even if the oxide is very fine particles, if its specific surface area is large, agglomerates will be formed during coating, which tends to cause unevenness, but lithium-manganese composite oxides with a small specific surface area are excellent. Coatability is ensured.
B ) リチウム ' マンガン複合酸化物を正極材料としたリチウ厶二次電 池の特性維持性能 （正極活物質材料の保持性， サイクル特性） にも リチウム ' マンガン複合酸化物の比表面積が大きく関わっており、 その比表面積が大きいと充電状態で高温に放置した場合の " Mnの溶 出" が顕著となり、 保持特性やサイクル特性が劣化しがちである。 本発明は、 上記知見事項等を基にしてなされたもので、 次に示すリチ ゥ厶二次電池用正極材料並びにリチウ厶二次電池を提供するものである c 1) 化学組成が U 4(0≤ x ≤0.20)で表される平均粒径 1 0 以下の粒子から成り、 かつ比表面積が 1 m z/g 以下であることを特 徴とする、 リチウム二次電池用正極材料。 B) The specific surface area of the lithium 'manganese composite oxide is also greatly affected by the characteristics maintenance performance (retention of the positive electrode active material, cycle characteristics) of the lithium secondary battery using the lithium' manganese composite oxide as the cathode material. If the specific surface area is large, the "dissolution of Mn" becomes remarkable when left at high temperature in the charged state, and the retention characteristics and cycle characteristics tend to deteriorate. The present invention has been made based on the above findings and the like, and provides the following positive electrode material for lithium secondary batteries and lithium secondary batteries. 1) the chemical composition consists of an average particle diameter of 1 0 or smaller particles represented by U 4 (0≤ x ≤0.20), and a specific surface area of the feature to be less than 1 m z / g, a lithium secondary Positive electrode material for secondary batteries.
2) 化学組成が U ,+xMn2-xO 4(0≤ X ≤0.20)で表される平均粒径 1 0 ； m以下の粒子から成り、 かっこの粒子を構成する 1 次粒子の粒径が 1 m以上であって、 比表面積が 1 m 2/g 以下であることを特徴とする、 リチウムニ次電池用正極材料。 2) The average particle diameter of the chemical composition represented by U, + x Mn 2 - x O 4 (0≤ X ≤0.20) 10; A positive electrode material for a lithium secondary battery, having a diameter of 1 m or more and a specific surface area of 1 m 2 / g or less.
3) 化学組成が Li , + xNIn2— xO 4(0≤ X ≤0.20)で表される平均粒径 1 0 Λ ΓΠ以下の粒子から成り、 かつ比表面積が 1 m g 以下である材料を正 極材料に適用して成ることを特徴とする、 リチウム二次電池。 3) Materials consisting of particles with a chemical composition of Li, + x NIn 2 — x O 4 (0 ≤ X ≤ 0.20) with an average particle size of 10 Λ ΓΠ or less and a specific surface area of 1 mg or less A lithium secondary battery characterized by being applied to a positive electrode material.
4) 化学組成が U , +xMn2-xO <(0≤ X ≤0.20)で表される平均粒径 1 0 m以下の粒子から成り、 かっこの粒子を搆成する 1 次粒子の粒径が 1 〃m以上であって、 比表面積が 1 m2/g 以下である材料を正極材料に適 用して成ることを特徴とする、 リチウム二次電池。 4) Particles composed of particles with an average particle size of 10 m or less represented by U, + xMn 2 - x O <(0≤ X ≤0.20) A lithium secondary battery characterized in that a material having a specific surface area of not less than 1 μm and a specific surface area of not more than 1 m 2 / g is applied to a positive electrode material.
このように、 本発明は、 "平均粒径が 1 0 m以下でかつ比表面積が  As described above, the present invention provides a method for producing an “average particle size of 10 m or less and a specific surface area of
1 m 7g 以下であるリチウム ' マンガン複合酸化物" の 「リチウムニ次 電池用正極材料としての有意性」 を見出して確認すると共に、 これをリ チウムニ次電池用正極材に用いることによってリチウム ■ マンガン複合 酸化物系リチウム二次電池の高温特性 （高温保持特性， 高温サイクル特 性） を改善できるようにした点に大きな特徴を有するものである。 図面の簡単な説明 In addition to finding and confirming the significance of lithium "manganese composite oxide" of 1 m7g or less as a positive electrode material for lithium secondary batteries, this lithium-manganese composite can be used by using it as a positive electrode material for lithium secondary batteries. A major feature is that the high-temperature characteristics (high-temperature holding characteristics and high-temperature cycle characteristics) of oxide-based lithium secondary batteries can be improved. BRIEF DESCRIPTION OF THE FIGURES
第 1 図は、 実施例にて得られた微細粒リチウム ， マンガン複合酸化物の電- 顕微鏡 ( S E M) 写真図である。  FIG. 1 is an electron microscope (SEM) photograph of the fine-grained lithium and manganese composite oxide obtained in the example.
第 2図は、 実施例及び比較例で作製したリチウム電池のサイクル試験 結果を比較したグラフである。 第 3図は、 比較例にて得られた微細粒リ チウム ' マンガン複合酸化物 の電子顕微鏡 （ S E M) 写真図である。 発明を実施するための最良の形態 FIG. 2 is a graph comparing the cycle test results of the lithium batteries produced in the example and the comparative example. FIG. 3 is an electron micrograph (SEM) of the fine-grained lithium-manganese composite oxide obtained in the comparative example. BEST MODE FOR CARRYING OUT THE INVENTION
以下、 本発明の実施の形態をその作用と共に詳述する。  Hereinafter, an embodiment of the present invention will be described in detail along with its operation.
本発明に係るリチウム ■ マンガン複合酸化物 （Li , + χΝ1η卜 xO Jの Xの 値を 「 0 ≤ X ≤ 0.20」 と限定したのは、 前記 Xの値が負の値になるとス ピネル構造が不安定になり、 また Xの値が 0.20を超えるとリチウ厶二次 電池の正極活物質とした際の放電容量が 1 0 0 mAh/g 以下となって、 何れもリチウ厶二次電池用材料としての実用上好ましくないからである, また、 リ チウム .マンガン複合酸化物 {Li， +χΜη2 χΟ ,(0≤ X ≤0.20)} に関し、 その平均粒径を 1 0 m以下としたのは、 これが "リチウム - マンガン複合酸化物が高温においても良好な電池特性 （特に高温サイク ル特性） を示すようになる必要条件" であることを解明したためである ( なお、 この高温でのサイクル特性はリチウム ' マンガン複合酸化物の夕 ップ密度が 1.8g/cms以上になると、 更には複合酸化物の最大粒径が 2 0 ； m以下に抑えられると一層顕著に改善される。 Lithium ■ manganese composite oxide according to the present invention (Li, + χ Ν1η Bok x the value of X in OJ The reason for limiting the "0 ≤ X ≤ 0.20", the scan when the value of X is a negative value Pinel structure When the value of X exceeds 0.20, the discharge capacity when used as the positive electrode active material of a lithium secondary battery becomes 100 mAh / g or less. The average particle size of the lithium-manganese composite oxide {Li, + χ χη2 χ (, (0≤X ≤0.20)} is less than 10 m. was is given by, which - because the elucidated to be a "lithium requirements manganese composite oxide becomes to be exhibit good battery characteristics (particularly high-temperature cycle characteristics) in a high temperature" (Note that in this high temperature cycle characteristics evening-up density of the lithium 'manganese composite oxide is more than 1.8 g / cm s , Even the maximum particle size of the composite oxide is 2 0; are more significantly improved when suppressed below m.
更に、 上記リ チウム ■ マンガン複合酸化物に関し "比表面積が 1 m 2/ g 以下" としたのは、 比表面積が 1 m2/g を上回っていると、 これをリ チゥ厶二次電池の正極材料として集電体に塗工する際の塗工性が比表面 積の小さいものに比べて悪くなり、 従来組成の電極膜形成スラ リ ーとし て集電体に塗工しょうとすると凝集粒が生成して塗工ムラを発生する頻 度が高くなって製品品質が不安定になりがちだからである。 Furthermore, regarding the above-mentioned lithium-manganese composite oxide, “the specific surface area is 1 m 2 / g or less” means that if the specific surface area exceeds 1 m 2 / g, this is The coating properties of the positive electrode material when applied to the current collector are worse than those with a small specific surface area. This is because the frequency of the generation of coating unevenness increases and the product quality tends to become unstable.
その上、 リチウム ' マンガン複合酸化物を正極材料としたリチウム二 次電池の特性維持性能（正極活物質材料の保持性， サイクル特性）にもリ チウ厶 ■ マンガン複合酸化物の比表面積が大きく関わっており、 その比 表面積が 1 m '/g よりも大きいと充電状態で高温に放置した場合の "Mn の溶出" が顕著となり、 保持特性やサイクル特性が劣化しがちである。 ところで、 酸化マンガンとリチウ厶化合物との反応によつてリチウム ■ マンガン複合酸化物が生成する過程では、 ます極めて微細なリチウム ' マンガン複合酸化物の一次粒子が生じ、 続いてこれら一次粒子同士が 互いに結合することと、 これが核となって粒成長することとが平行して 進行することにより二次拉子が形成され、 反応が終了するものと考えら れる。 そのため、 得られたリチウム ■ マンガン複合酸化物の粒子を観察 すると、 大きく成長した二次粒子の表面に微細粒の一次粒子が付着して 一体化した構造となっていることが認められる。 In addition, the lithium-manganese composite oxide also has a positive effect on lithium secondary battery characteristics maintenance performance (retention and cycling characteristics of the positive electrode active material). The ratio If the surface area is greater than 1 m '/ g, "leaching of Mn" becomes remarkable when left at high temperature in a charged state, and the retention characteristics and cycle characteristics tend to deteriorate. By the way, in the process of producing lithium ■ manganese composite oxide by the reaction between manganese oxide and lithium compound, extremely fine primary particles of lithium 'manganese composite oxide are generated, and then these primary particles are mutually bonded. It is considered that the secondary abscission is formed and the reaction is completed by the parallel progress of the bonding and the nucleation and grain growth. Therefore, when observing the obtained lithium-manganese composite oxide particles, it is recognized that the primary particles of the fine particles adhere to the surface of the large-grown secondary particles to form an integrated structure.
そして、 本発明者等の検討により、 リチウム ■ マンガン複合酸化物の 組成， 粒径並びに比表面積がリチウムニ次電池用正極材料としての特性 に大きく影響することは前述した通りであるが、 リチウム ' マンガン複 合酸化物における上記一次粒子 （成長した二次粒子の表面に付着した微 細粒の粒子として観察される） の粒径も比表面積を通じて "リチウム二 次電池用正極材料としてのリチウム ■ マンガン複合酸化物" の特性に影 響するものであり、 この一次粒子の粒径が 1 a m以上であるリチウム ■ マンガン複合酸化物が塗工性や電池特性の点で好ましいことも分かった 上述のような "平均粒径が 1 0 m以下であってかつ比表面積が 1 m ' /g以下であるリチウム · マンガン複合酸化物 {Li , + xMn2— xO 4 (0≤ x ≤ 0.20)} "、 更には一次粒子の粒径が 1 以上であるリチウム ■ マンガ ン複合酸化物は、 平均粒径が 10^ m以下の酸化マンガン （Nln02， Mn20 ! あるいは Mn304) とリ チウム化合物 （炭酸リ チウム等） を所定割合で混 合し焼成することにより製造することができるが、 予備試験によって焼 成反応原料を厳選することが重要である。 According to the studies by the present inventors, as described above, the composition, particle size, and specific surface area of the lithium-manganese composite oxide greatly affect the characteristics as a positive electrode material for a lithium secondary battery. The particle size of the above primary particles (observed as fine particles attached to the surface of the grown secondary particles) in the composite oxide also increases through the specific surface area of the lithium-manganese composite as a positive electrode material for lithium secondary batteries. It has also been found that lithium ■ manganese composite oxides, in which the primary particles have a particle size of 1 am or more, are preferable in terms of coatability and battery characteristics. "Lithium-manganese composite oxide with an average particle size of 10 m or less and a specific surface area of 1 m '/ g or less {Li, + x Mn 2 — x O 4 (0≤ x ≤ 0.20)}" And of the primary particles Particle size is 1 or more lithium ■ manganese composite oxide has an average particle diameter of 10 ^ m or less manganese oxide (Nln0 2, Mn 2 0! Or Mn 3 0 4) and Lithium compound (carbonate Lithium etc. ) Can be manufactured by mixing and firing at a predetermined ratio, but it is important to carefully select the firing reaction raw materials through preliminary tests.
この場合の焼成温度としては 4 5 0〜 9 0 0 °Cの範囲が適当であるが、 使用する原料に応じて所望の "平均粒径"， "比表面積"， "一次粒子の粒 径" が得られる焼成条件 （焼成温度等） を予備試験によって把握してお き、 最適条件で焼成するのが良い。 なお、 焼成温度が 4 5 0 °C未満では, Li , + xMn2 -x O の結晶性が上がらないために電池材とした場合の放電容 量が低下しがちとなり、 また 9 0 0 °Cを超えると焼成時に Li , + iJn2-xO , からの酸素の放出が顕著になつて異相が生成するなどし、 やはり電池材 とした場合の放電容量が低下する傾向を見せるので好ましくない。 The firing temperature in this case is suitably in the range of 450 to 900 ° C. Preliminary examination of firing conditions (firing temperature, etc.) to obtain the desired "average particle size", "specific surface area", and "primary particle size" according to the raw materials used, and firing under the optimal conditions Good to do. In the firing temperature is 4 5 0 ° less than C, Li, + x Mn 2 -x discharge capacity in the case of a battery material for the crystallinity does not increase the O becomes apt to decrease, also 9 0 0 ° Exceeding C is preferable because the release of oxygen from Li, + i Jn 2 - x O, during sintering becomes noticeable and a heterogeneous phase is formed, which also tends to reduce the discharge capacity when used as a battery material. Absent.
なお、 所望する微細粒リチウム ■ マンガン複合酸化物 {Li , + χΜηζ χ θ , (0≤ x ≤0.20) } を得るためには、 好ましく は焼成原料である酸化マン ガンとしてタップ密度が 1.8g/cm5以上のもの、 より好ましくは粒子形状 が球状であるものを使用するのが良い。 Incidentally, the desired fine particle lithium ■ manganese composite oxide {Li, + χ Μη ζ χ θ, (0≤ x ≤0.20)} in order to obtain the tap density as the oxidizing manganese is preferably calcined material 1.8 It is preferable to use those having a g / cm 5 or more, more preferably those having a spherical particle shape.
焼成原料としての酸化マンガン （Mn02， Mnz 05, n, 04 ) は、 微細 拉炭酸マンガンを空気中にて 3 0 0 °C以上で熱処理することによって生 成させることができるが、 より好適な酸化マンガン原料は、 粒子形状が 球状の炭酸マンガンを酸素濃度 1 5 %未満の雰囲気中 （好ましく は窒素 雰囲気中） において 6 0 0〜 9 0 0 °Cという高めの温度で熱処理 （第 1 段目の熱処理） し、 引き続いて更に酸素濃度 1 5 %以上の雰囲気中にて 5 3 0〜 8 0 0 °Cという低めの温度で熱処理 （第 2段目の熱処理） する ことによつて製造することができる。 Manganese oxide as sintering raw material (Mn0 2, Mn z 0 5 , n, 0 4) is a fine拉炭manganese can be made viable by heat treatment at in air 3 0 0 ° C or higher, A more preferable manganese oxide raw material is to heat-treat manganese carbonate having a spherical particle shape in an atmosphere having an oxygen concentration of less than 15% (preferably in a nitrogen atmosphere) at a high temperature of 600 to 900 ° C. The first heat treatment) followed by a further heat treatment (second heat treatment) at a lower temperature of 530 to 800 ° C in an atmosphere with an oxygen concentration of 15% or more. Can be manufactured.
この処理方法は、 微細粒で比表面積の小さいリチウム ' マンガン複合 酸化物の製造に好適な微細粒 Mn, 0 , を得るものであり、 第 1 段目の熱 処理によって多孔質の MnO 2 が生じることなく低酸化状態のマンガン酸 化物が生成するが、 この際の雰囲気中酸素濃度が 1 5 %以上であると多 孔性の MnO z が生成し、 好適なリチウム ■ マンガン複合酸化物合成用原 料とはならない。 また、 この際の熱処理温度が 6 0 0 °C未満であると低 酸化状態のマンガン酸化物を効果的に得ることができず、 一方、 9 0 0 °Cを超えると生成する酸化マンガンの凝集が著しくなつて不定形粒が増 加し、 リチウムニ次電池用リチウム ， マンガン複合酸化物の原料として 好適な微細酸化マンガンが得られなくなる。 This treatment method obtains fine particles Mn, 0, which are suitable for the production of lithium manganese composite oxides having a small specific surface area and a small specific surface area, and porous MnO 2 is generated by the first stage heat treatment. manganese oxides of low oxidation state is generated without, this atmosphere of oxygen concentration when is generated MnO z multi porous and is 1 5% or more, preferably lithium ■ manganese composite oxide synthesis Hara There is no charge. If the heat treatment temperature at this time is lower than 600 ° C., a manganese oxide in a low oxidation state cannot be obtained effectively. When the temperature exceeds ° C, the formed manganese oxide is remarkably agglomerated and irregular particles increase, so that fine manganese oxide suitable as a raw material for lithium and manganese composite oxides for lithium secondary batteries cannot be obtained.
さて、 上記の第 1 段目熱処理を施すことによって高夕ップ密度の酸化 マンガンが生成されるが、 低酸素濃度のままでは Μη, Ο , 単相になるま でに長い時間がかかる。  By performing the first-stage heat treatment, manganese oxide with a high density is generated, but it takes a long time to form Μη, ,, and a single phase at low oxygen concentration.
そのため、 タップ密度が増加したところで酸素濃度を 1 5 %以上にま で高め、 Mns C が Mnz O , に変換する時間の短縮を図るべく第 2段目の 熱処理が施される。 この第 2段目熱処理での処理温度が 5 3 0 °C未満で あったり、 熱処理雰囲気中酸素濃度が 1 5 %未満であったりすると、 混 入している Μη, Ο , が Μη, Ο , に速やかに変換されず、 処理に長時間を要 したり製品性能の悪化を招くおそれが出てく る。 また、 第 2段目熱処理 での処理温度が 8 0 0 °Cを超えると、 やはり得られる酸化マンガンの凝 集が著しくなつて微細で高夕ップ密度の酸化マンガンが得られなくなる ( ここで、 Μη, Ο , を Μη, Ο , へ変換するための熱処理温度の切り替えは、 低酸化状態の酸化マンガンの生成時と同時であっても良く、 必ずしも熱 処理雰囲気中酸素濃度を 1 5 %以上に高めた時点である必要はない。 なお、 この酸化マンガン （Mnz O s) の製造方法に適用される球状の炭 酸マンガン原料は、 「硫酸マンガン溶液と重炭酸アンモニゥムもしく は 重炭酸ナ ト リ ウムを混合する方法」 や 「アンモニゥ厶イオンを含む溶液 に金属マンガンを溶解させ、 所定のマンガン濃度に達した後に C 02 ガ スを通気する方法 （特許第 3 0 3 2 9 7 5号に係る方法） 」 等によって 製造することができる。 Therefore, increase in Nima oxygen concentration of 1 5% or more where the tap density is increased, the second-stage heat treatment is performed to shorten the time Mns C converts Mn z O, the. If the treatment temperature in the second stage heat treatment is lower than 530 ° C or the oxygen concentration in the heat treatment atmosphere is lower than 15%, し η, Ο, contained 混 η, Ο, It may not be converted quickly to a long time, and it may take a long time to process or deteriorate the performance of the product. Further, the treatment temperature in the second stage heat treatment is greater than 8 0 0 ° C, manganese oxide high evening-up density can not be obtained by also obtained oxide agglutination significantly Do connexion fine manganese (here The switching of the heat treatment temperature for converting へ η, Ο, to 変 換 η, Ο, may be performed at the same time as the generation of manganese oxide in a low oxidation state, and the oxygen concentration in the heat treatment atmosphere is not less than 15%. need not be a time of enhanced. Note that carbonated manganese raw material spherical applied to the method for producing manganese oxide (Mn z O s) are "manganese sulfate solution and bicarbonate Anmoniumu also is properly bicarbonate Na dissolved bets method of mixing Li um "and" Anmoniu厶solution manganese metal containing ions, a method for venting a C 0 2 gas after a predetermined manganese concentration (No. 3 0 3 2 9 7 5 No.)) Can be built.
上述した 「化学組成が Li , + xMn2-x O ,(0≤ X ≤0.20)で、 平均粒径 1 0 ； m以下の粒子から成り、 かつ比表面積が 1 m '/g 以下であるか、 更に は 1 次粒子の粒径が 1 m以上であるリチウム ■ マンガン複合酸化物」 は、 これをリチウムニ次電池の正極活物質として適用することにより、 その電池特性、 とりわけ高温での保持特性， サイクル特性を著しく向上 させることが可能である。 As mentioned above, “The chemical composition is Li, + x Mn 2 -x O, (0≤X ≤0.20), the average particle size is 10; the particles are less than m, and the specific surface area is 1 m '/ g or less. Or lithium whose primary particles have a particle size of 1 m or more. By applying this as a positive electrode active material for lithium secondary batteries, it is possible to significantly improve the battery characteristics, especially the high-temperature retention characteristics and cycle characteristics.
従って、 上記リチウム ■ マンガン複合酸化物を使用することによって、 特性維持性能をも含めた電池特性の優れた比較的安価なリチウ厶二次電 池を実現することができる。  Therefore, by using the above-mentioned lithium-manganese composite oxide, it is possible to realize a relatively inexpensive lithium secondary battery having excellent battery characteristics including the characteristic maintenance performance.
次いで、 実施例及び比較例によつて本発明を更に具体的に説明する。 〔実施例〕  Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. 〔Example〕
ます、 硫酸アンモニゥ厶に金属マンガンを溶解し、 この溶解液に炭酸 ガスを導入して炭酸マンガンを析出させる方法によって平均粒径が 6.9 mの球状微細粒炭酸マンガンを製造した。  First, spherical manganese carbonate having an average particle size of 6.9 m was produced by dissolving metallic manganese in ammonium sulfate and introducing carbon dioxide gas into the solution to precipitate manganese carbonate.
次に、 得られた炭酸マンガンを出発原料とし、 これに窒素中で 8 0 0 °Cにて 1 時間の熱処理を施し、 引き続いて雰囲気中に酸素を導入して雰 囲気中酸素濃度を 2 0 %に変え、 この雰囲気中にて 6 5 0 °Cで更に 1 時 間の熱処理を施すことによって、 平均粒径が 7 ^ mの Μη,Ο , を得た。 この微細粒 Μη:0 , の 1 2 g と炭酸リチウム 3.17 g とを混合した後、 空気中にて 7 5 0 °Cで 1 0時間焼成した。  Next, the obtained manganese carbonate was used as a starting material, and this was subjected to a heat treatment at 800 ° C. for 1 hour in nitrogen, and oxygen was subsequently introduced into the atmosphere to reduce the oxygen concentration in the atmosphere to 20%. %, And heat treatment was further performed at 65 ° C. for 1 hour in this atmosphere to obtain Μη, Ο with an average particle size of 7 ^ m. After mixing 12 g of the fine particles Μη: 0, with 3.17 g of lithium carbonate, the mixture was fired in air at 750 ° C. for 10 hours.
得られた化合物の粉末を粉末 X線回折測定したところ、 Li ,+xMn2-xO < 単相 （0≤ x ≤0.20) であることを確認した。 The obtained powder of the compound was measured powder X-ray diffraction, Li, + x Mn 2 - was confirmed to be x O <single phase (0≤ x ≤0.20).
なお、 このリ チウム ■ マンガン複合酸化物 {Li i+ xMn! x O , (0≤ X ≤ The lithium-manganese composite oxide (Li i + xMn! X O, (0≤ X ≤
0.20) } 粒子は平均粒径が 7 mで比表面積が 0.7m z/g であり、 酸化 マンガンの数値を引き継ぐものであった。 0.20)} particles specific surface area average particle diameter of 7 m is 0.7 m z / g, were those taking over the value of the manganese oxide.
更に、 得られた上述のリチウム.マンガン複合酸化物 {Li , + χΜη2— χΟ < (0≤ X ≤ 0.20) } 粒の形状を S E M (Scanning Electron Microscope： 走査型電子顕微鏡） を用いて観察することにより、 1 次粒子の粒径が 1 U m以上であることを確認した。 なお、 図 1 は得られたリチウ厶 ■ マンガン複合酸化物の S E M写真図 である。 Furthermore, lithium obtained above manganese oxide {Li, + χ Μη 2 - χ Ο <(0≤ X ≤ 0.20)} grain shape SEM. (Scanning Electron Microscope: scanning electron microscope) using a Observation confirmed that the particle size of the primary particles was 1 Um or more. Figure 1 is a SEM photograph of the obtained lithium-manganese composite oxide.
次に、 得られた上記リチウ厶 ' マンガン複合酸化物の塗工性を評価し た。  Next, the coatability of the obtained lithium manganese composite oxide was evaluated.
塗工性の評価は、 得られたリチウム ■ マンガン複合酸化物を正極活物 質として 8 5 wt % , 結着材としてポリ弗化ビニリデンを 7 wt %、 導電材 としてアセチレンブラックを 8 wt %それぞれ計量し、 これに分散媒とし てァセ トンを加えてスラリ一とした後、 これをアルミニウム箔上にハン ドコ一夕一により塗布して塗布状態を観察するという手法によった。 この結果、 塗装スジが発生することなく均一厚の塗膜が形成され、 本 発明正極材料は優れた塗工性を有していることが確認された。  The applicability was evaluated using the obtained lithium ■ manganese composite oxide as the positive electrode active material at 85 wt%, polyvinylidene fluoride as the binder 7 wt%, and acetylene black as the conductive material 8 wt%. It was weighed and added with acetone as a dispersion medium to form a slurry, which was then applied to an aluminum foil with a hand and iron to observe the applied state. As a result, a coating film having a uniform thickness was formed without generation of coating streaks, and it was confirmed that the positive electrode material of the present invention had excellent coatability.
更に、 得られた上記リチウム ■ マンガン複合酸化物の高温での Mn溶出 量を調査した。  Further, the amount of Mn eluted at a high temperature in the obtained lithium リ チ ウ ム manganese composite oxide was investigated.
Mn溶出量の調査は、 リ チウム ■ マンガン複合酸化物を 5 5 °Cの電解液 に 1 週間浸潰した後の Mn溶出量を I C P (誘導結合プラズマ法） で測定 する手法によって実施した。 なお、 電解質としては 1 モルの L i P F s を 含むエチレンカーボネー 卜とジメチルカーボネー 卜の混合物 （混合比 = 2 : 1 ) を用いた。 The amount of Mn eluted was investigated by a method of measuring the amount of Mn eluted by inductively coupled plasma (ICP) after immersing the lithium-manganese composite oxide in an electrolyte solution at 55 ° C for 1 week. Incidentally, ethylene carbonate Natick Bok and dimethyl carbonate Natick mixture Bok The electrolyte containing 1 mole of L i PF s (mixing ratio = 2: 1) was used.
この結果、 測定された Mn溶出量はリチウム ■ マンガン複合酸化物 1 g 当り 0. 3mgであって、 従来材のリ チウム ■ マンガン複合酸化物 1 g当り 1 mg程度に比べて著しく改善されていることが確認され、 本発明正極材 料では Mn系正極材料で最も懸念されている高温特性の劣化 （高温での Mn の電解液への溶出） が顕著に抑制されることが分かつた。  As a result, the measured amount of Mn eluted was 0.3 mg per 1 g of lithium ■ manganese composite oxide, which is remarkably improved compared to about 1 mg per 1 g of lithium ■ manganese composite oxide of the conventional material. It was confirmed that in the cathode material of the present invention, deterioration of high-temperature characteristics (elution of Mn into the electrolyte at a high temperature), which is the most concerned about Mn-based cathode materials, was remarkably suppressed.
また、 得られたリチウム ■ マンガン複合酸化物を正極活物質と したリ チウムニ次電池の特性調査も行った。  In addition, the characteristics of lithium secondary batteries using the obtained lithium-manganese composite oxide as the positive electrode active material were also investigated.
この調査に当っては、 まず、 得られたリチウム ■ マンガン複合酸化物 {Li Ο , (0≤ x ≤0.20)} を活物質として 8 5 wt%、 導電材とし てのアセチレンブラックを 8 wt%、 そして結着材としてのポリ弗化ビニ リデンを 7 v»t%それぞれ計量し、 これに分散媒としてァセ 卜ンを加えて スラリーとした後、 これをアルミ箔上に塗布してから溶媒を蒸発させて リチウム電池の正電極を作製した。 そして、 対極にはリチウムメタル、 そして電解質 （電解液） と して 1 モルの Li P F f を含むエチレンカーボ ネー 卜とジメチルカーボネー 卜との混合物 （混合比 = 1 ： 1 ) を用いて リチウム電池であるコインセル （ C R 2 0 3 2 ) を作製した。 In this survey, first, the obtained lithium ■ manganese composite oxide 85% by weight of {Li ,, (0≤ x ≤0.20)} as active material, 8% by weight of acetylene black as conductive material, and 7 v »t% of polyvinylidene fluoride as binder Each was weighed, and acetonitrile was added as a dispersion medium to form a slurry. The slurry was applied on an aluminum foil, and then the solvent was evaporated to prepare a positive electrode of a lithium battery. Then, lithium metal as a counter electrode, and an electrolyte (electrolyte solution) and to ethylene carbonate Natick Bok and dimethyl carbonate Natick Bok and mixtures containing one mole of Li PF f (mixing ratio = 1: 1) lithium batteries using A coin cell (CR2032) was prepared.
このコイ ンセルについて、 5 5 °C， 1 C一 1 C充放電条件でのサイク ル試験を行ったが、 この試験の結果を図 2に示す。  This coin cell was subjected to a cycle test under the conditions of 55 ° C and 1C-11C charge / discharge. Figure 2 shows the results of this test.
図 2に示される結果からも明らかなように、 本発明の規定条件を満た すリチウム ■ マンガン複合酸化物を正極活物質としたリチウ厶電池は高 温 （ 5 5 °C) でのサイクル特性に優れていることが明らかであり、 前記 の Mn溶出量調査の結果とも併せて優れた保持特性を有していることも確 認できる。  As is clear from the results shown in Fig. 2, the lithium battery that satisfies the specified conditions of the present invention using lithium-manganese composite oxide as the positive electrode active material has high cycle characteristics at high temperature (55 ° C). It is clear that it is excellent, and it can also be confirmed that it has excellent retention characteristics in combination with the result of the above-mentioned Mn elution amount investigation.
〔比較例〕  (Comparative example)
前記実施例において製造された平均粒径が 6.9 mの球状微細粒炭酸 マンガンを出発原料とし、 これに窒素中にて 6 5 0 X)で 1 時間の熱処理 を施した後、 引き続いて雰囲気中に酸素を導入して雰囲気中酸素濃度を 2 0 %に変え、 この雰囲気中にて更に同じ 6 5 0 °Cで 1 時間の熱処理を 施すことによって、 平均粒径が 7 〃 の Mn20 , を得た。 The spherical fine-grained manganese carbonate having an average particle size of 6.9 m produced in the above example was used as a starting material, and this was subjected to a heat treatment at 650 X) in nitrogen for 1 hour, and subsequently into an atmosphere. Oxygen was introduced to change the oxygen concentration in the atmosphere to 20%, and heat treatment was further performed in the atmosphere at the same temperature of 65 ° C. for 1 hour to obtain Mn 20 , having an average particle size of 7 μm. Obtained.
この微細拉 Mn:0， の 1 2 gと炭酸リチウ厶 3.17 gとを混合した後、 空気中にて 7 5 0 °Cで 1 0時間焼成した。  After mixing 12 g of the fine particles Mn: 0, and 3.17 g of lithium carbonate, the mixture was baked in air at 750 ° C. for 10 hours.
得られた化合物の粉末を粉末 X線回折測定したところ、 L +χΝΙη2-χΟ , 単相 （0≤ x ≤0.20) であることを確認した。 The powder of the obtained compound was subjected to powder X-ray diffraction measurement. As a result, it was confirmed that L + ΝΙ ΝΙ η 2 - χ , was a single phase (0≤x≤0.20).
なお、 このリチウム ■ マンガン複合酸化物 {ϋ ,+xMn2— xO 4 (0≤ X ≤ 0.20) } 粒子は、 平均粒径は 7 mであったものの、 比表面積が 1.3m ' /gであつた。 Note that this lithium ■ manganese composite oxide {ϋ, + x Mn 2 — x O 4 (0≤ X ≤ 0.20)} Although the particles had an average particle size of 7 m, the specific surface area was 1.3 m '/ g.
更に、 得られたリチウム ■ マンガン複合酸化物 {υ, +χΜη,— χ Ο , (0≤ X ≤0.20) } 粒の形状を S Ε Μを用いて観察することにより、 1 次粒子 の粒径が 1 〃 mを下回っていることが確認された。  Furthermore, by observing the shape of the obtained lithium ■ manganese composite oxide {υ, + χΜη, — χ ,, (0≤ X ≤0.20)} particles using S Ε 、, the particle size of the primary particles Was found to be less than 1 〃 m.
なお、 図 3は、 この比較例によって得られたリチウム ■ マンガン複合 酸化物の S E M写真図である。  FIG. 3 is a SEM photograph of the lithium-manganese composite oxide obtained by this comparative example.
次に、 得られたリチウム ■ マンガン複合酸化物の塗工性を前記実施例 の場合と同様の手法によつて評価した。  Next, the coatability of the obtained lithium-manganese composite oxide was evaluated by the same method as in the above-mentioned Example.
この結果、 塗布の途中で凝集粒が原因で塗膜にスジが入ることがある など塗工性が十分ではなく、 均一厚の塗膜を安定製造するためには難点 があると評価された。 なお、 この塗工性の低評価は、 リチウム ' マンガ ン複合酸化物の比表面積が大きいために凝集粒が生成したことに起因す るものであると考えられる。  As a result, the coating properties were not sufficient, such as streaks in the coating film due to agglomerated particles during coating, and it was evaluated that there were difficulties in stably producing a coating film having a uniform thickness. This low evaluation of the coating property is considered to be due to the formation of aggregated particles due to the large specific surface area of the lithium-manganese composite oxide.
更に、 得られた上記リチウム ' マンガン複合酸化物の高温での Mn溶出 量についても、 前記実施例の場合と同様の手法によって測定した。  Further, the amount of Mn eluted at a high temperature in the obtained lithium-manganese composite oxide was measured by the same method as in the above-mentioned Example.
この結果、 測定された Mn溶出量はリチウム ■ マンガン複合酸化物 1 g 当り 0.7mgであり、 Mn系正極材料で懸念されている高温特性の劣化 （高 温での Mnの電解液への溶出） が生じることが分かった。  As a result, the measured elution amount of Mn was 0.7 mg per 1 g of lithium ■ manganese composite oxide, deteriorating the high-temperature characteristics of Mn-based cathode materials (Mn elution into electrolyte at high temperatures) Was found to occur.
また、 本比較例で得られたリチウム ■ マンガン複合酸化物を正極活物 質とし、 そのほかは前記実施例と同様にリチウ厶電池であるコインセル ( C R 2 0 3 2 ) を作製して、 そのサイクル特性を調べた。  In addition, a lithium cell, a lithium battery, was used as a positive electrode active material, and a coin cell (CR2032) as a lithium battery was prepared in the same manner as in the previous example. The characteristics were investigated.
5 5 °C, 1 C - 1 C充放電条件でのサイクル試験の結果を、 前記図 2 に併せて示す。  The results of the cycle test under the conditions of 55 ° C and 1 C-1 C charge / discharge are also shown in FIG.
図 2に示される結果からも明らかなように、 平均粒径が 1 0 m以下 のリチウ厶 ■ マンガン複合酸化物であってもその比表面積が 1 m g を 超えるものでは、 これを正極活物質としてリチウ厶二次電池を作製する と、 比表面積が 1 m ' /g 以下のリチウム ' マンガン複合酸化物を正極活 物質としたものに比べてその高温サイクル特性に劣ることが確認できる。 また、 前記の Mn溶出量調査の結果とも併せれば、 本比較例で得られたリ チウ厶 ■ マンガン複合酸化物を正極活物質とするリチウムニ次電池は、 高温保持特性の点でも比表面積が 1 m 2 /g 以下のリチウム ' マンガン複 合酸化物を正極活物質としたものに比べて劣るであろうことが明らかで ある。 産業上の利用可能性 As is evident from the results shown in Fig. 2, lithium with an average particle size of 10 m or less ■ Even if the manganese composite oxide has a specific surface area of 1 mg If the lithium secondary battery is used as a positive electrode active material to produce a lithium secondary battery, its high-temperature cycle characteristics will be higher than those using a lithium manganese composite oxide with a specific surface area of 1 m '/ g or less as the positive electrode active material. Can be confirmed to be inferior. In addition, when combined with the results of the above-described Mn elution amount investigation, the lithium secondary battery using the lithium ■ manganese composite oxide obtained in this comparative example as a positive electrode active material also has a specific surface area in terms of high-temperature retention characteristics. It is evident that it will be inferior to those using a lithium manganese composite oxide of 1 m 2 / g or less as the positive electrode active material. Industrial applicability
この発明によれば、 塗工性に優れると共に優れた高温特性を備えたリ チウムニ次電池用正極材料を提供することができ、 また電池特性の優れた 比較的安価なリチゥ厶二次電池を実現することを可能にするなど、 産業 上極めて有用な効果がもたらされる。  According to the present invention, it is possible to provide a cathode material for a lithium secondary battery having excellent coatability and excellent high-temperature characteristics, and realize a relatively inexpensive lithium secondary battery having excellent battery characteristics. It has an extremely useful effect on industry, such as enabling

Claims

請 求 の 範 囲 The scope of the claims
1 . 化学組成が U ,+xMn2— χθ « (0≤ x ≤0.20) で表される平均粒径 1 0 m以下の粒子から成り、 かつ比表面積が 1 m z/g 以下であることを持 徵とする、 リチウム二次電池用正極材料。 . 1 Chemical composition U, + x Mn 2 - χθ « it (0≤ x ≤0.20) consists average particle size 1 0 m or smaller particles represented by, and a specific surface area of less than 1 m z / g A positive electrode material for lithium secondary batteries.
2. 化学組成が L +xMn,— xO 4 (0≤ X ≤0.20) で表される平均粒径 1 0 m以下の粒子から成り、 かっこの粒子を構成する 1 次粒子の粒径が 1 m以上であって、 比表面積が 1 m 2/g 以下であることを特徴とする、 リチウムニ次電池用正極材料。 2. It consists of particles with an average particle size of 10 m or less, whose chemical composition is represented by L + x Mn, — x O 4 (0≤ X ≤0.20). A positive electrode material for a lithium secondary battery, having a specific surface area of at least 1 m and a specific surface area of at most 1 m 2 / g.
3. 化学組成が Li , + χΜη,-χ Ο (0≤ χ ≤ 0.20) で表される平均粒径 1 0 m以下の粒子から成り、 かつ比表面積が 1 m '/g 以下である材料を正 極材料に適用して成ることを特徴とする、 リチウムニ次電池。  3. Materials composed of particles with an average particle diameter of 10 m or less represented by Li, + χΜη, -χ Ο (0≤ χ ≤ 0.20) and a specific surface area of 1 m '/ g or less A lithium secondary battery characterized by being applied to a positive electrode material.
4. 化学組成が U ,+xMnz-xO , (0≤ X ≤0.20) で表される平均粒径 1 0 U m以下の粒子から成り、 かっこの粒子を構成する 1 次粒子の粒径が 1 m以上であって、 比表面積が 1 m:/g 以下である材料を正極材料に適 用して成ることを特徴とする、 リ チウム二次電池。 4. Particles with a mean particle size of 10 Um or less expressed as U, + x Mn z - x O, (0≤ X ≤0.20) A lithium secondary battery characterized in that a material having a diameter of 1 m or more and a specific surface area of 1 m : / g or less is applied to a positive electrode material.
PCT/JP2001/001254 2000-04-11 2001-02-21 Positive electrode material for lithium secondary cell and lithium secondary cell using the same WO2001078168A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2000115777A JP2001297767A (en) 2000-04-11 2000-04-11 Lithium secondary cell and positive electrode material for the same
JP2000/115777 2000-04-11

Publications (1)

Publication Number Publication Date
WO2001078168A1 true WO2001078168A1 (en) 2001-10-18

Family

ID=18627343

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2001/001254 WO2001078168A1 (en) 2000-04-11 2001-02-21 Positive electrode material for lithium secondary cell and lithium secondary cell using the same

Country Status (2)

Country Link
JP (1) JP2001297767A (en)
WO (1) WO2001078168A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4940530B2 (en) * 2003-02-05 2012-05-30 日亜化学工業株式会社 Cathode active material for non-aqueous electrolyte secondary battery
JP2005221842A (en) * 2004-02-06 2005-08-18 Lintec Corp Member for mask film, method for manufacturing mask film using the same, and method for manufacturing photosensitive resin printing plate

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10218662A (en) * 1997-02-03 1998-08-18 Toray Ind Inc Production of zirconia sintered compact
JPH10321227A (en) * 1997-05-23 1998-12-04 Asahi Chem Ind Co Ltd Nonaqueous electrolyte secondary battery
JPH11121006A (en) * 1997-10-17 1999-04-30 Toyota Central Res & Dev Lab Inc Positive electrode active material for lithium secondary battery
JP2000012031A (en) * 1997-06-13 2000-01-14 Hitachi Maxell Ltd Positive active material for nonaqueous electrolyte secondary battery, its manufacture, and the nonaqueous electrolyte secondary battery using the positive active material
JP2000090982A (en) * 1998-07-14 2000-03-31 Denso Corp Nonaqueous electrolyte secondary battery

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10218662A (en) * 1997-02-03 1998-08-18 Toray Ind Inc Production of zirconia sintered compact
JPH10321227A (en) * 1997-05-23 1998-12-04 Asahi Chem Ind Co Ltd Nonaqueous electrolyte secondary battery
JP2000012031A (en) * 1997-06-13 2000-01-14 Hitachi Maxell Ltd Positive active material for nonaqueous electrolyte secondary battery, its manufacture, and the nonaqueous electrolyte secondary battery using the positive active material
JPH11121006A (en) * 1997-10-17 1999-04-30 Toyota Central Res & Dev Lab Inc Positive electrode active material for lithium secondary battery
JP2000090982A (en) * 1998-07-14 2000-03-31 Denso Corp Nonaqueous electrolyte secondary battery

Also Published As

Publication number Publication date
JP2001297767A (en) 2001-10-26

Similar Documents

Publication Publication Date Title
JP4894969B1 (en) Nickel-manganese composite hydroxide particles and production method thereof, positive electrode active material for non-aqueous electrolyte secondary battery and production method thereof, and non-aqueous electrolyte secondary battery
JP4915488B1 (en) Nickel-manganese composite hydroxide particles and production method thereof, positive electrode active material for non-aqueous electrolyte secondary battery, production method thereof, and non-aqueous electrolyte secondary battery
JP5971109B2 (en) Nickel composite hydroxide and production method thereof, positive electrode active material for non-aqueous electrolyte secondary battery, production method thereof, and non-aqueous electrolyte secondary battery
KR101948321B1 (en) Positive electrode active material precursor particulate powder and positive electrode active material particulate powder, and non-aqueous electrolyte secondary battery
JP5708277B2 (en) Nickel-manganese composite hydroxide particles and production method thereof, positive electrode active material for non-aqueous electrolyte secondary battery and production method thereof, and non-aqueous electrolyte secondary battery
JP5590337B2 (en) Manganese composite hydroxide particles, positive electrode active material for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and production methods thereof
EP3683870A1 (en) Manganese spinel doped with magnesium, cathode material comprising same, method for preparing same and lithium ion battery comprising same
JP4299065B2 (en) Positive electrode material for lithium secondary battery and method for producing the same
KR20110094023A (en) Powder of lithium complex compound particles, method for producing the same, and nonaqueous electrolyte secondary cell
WO2004010519A1 (en) Method for producing positive plate material for lithium secondary cell
JP6848249B2 (en) Positive electrode active material for non-aqueous electrolyte secondary battery and its manufacturing method, and non-aqueous electrolyte secondary battery
KR20140138780A (en) Positive electrode active material particle powder and method for producing same, and non-aqueous electrolyte secondary battery
WO2021054468A1 (en) Positive electrode active material for lithium ion secondary battery, and lithium ion secondary battery
JP6544579B2 (en) Method for producing lithium tungstate, and method for producing positive electrode active material for non-aqueous electrolyte secondary battery using lithium tungstate
TWI622212B (en) Cathode compositions for lithium-ion batteries
JP2021048070A (en) Positive electrode active material for lithium ion secondary battery and lithium ion secondary battery
JP2005123180A (en) Lithium compound oxide particle for positive electrode material of lithium secondary battery and its manufacturing method, and lithium secondary battery positive electrode using them and the lithium secondary battery
US7575831B2 (en) Co-precipitation method for the preparation of Li1+xNi1-yCoyO2-based cathode materials
KR102015425B1 (en) Positive active material for lithium secondary battery with copper-manganese coating thereon, lithium secondary battery having the same, and method for manufacturing thereof
JP2021048071A (en) Positive electrode active material for lithium ion secondary battery and lithium ion secondary battery
JP2022177291A (en) Positive electrode active material for high-strength lithium ion secondary battery, and lithium ion secondary battery employing the positive electrode active material
WO2021054467A1 (en) Positive electrode active material for lithium ion secondary battery, and lithium ion secondary battery
WO2001078168A1 (en) Positive electrode material for lithium secondary cell and lithium secondary cell using the same
JP2006232608A (en) Oxide with rock salt type crystal structure, lithium-nickel multiple oxide using the same, method for producing the same and method for producing lithium secondary battery using the same
JP3495639B2 (en) Lithium-manganese composite oxide, method for producing the same, and lithium secondary battery using the composite oxide

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CN KR US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase