Classifications

• • 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 method for producing composite metal oxides, which are positive electrode active materials for lithium ion secondary batteries. More specifically, the present invention relates to a method for producing Li-Ni-Co-Mn composite metal oxides and Li-Ni-Co-Al composite metal oxides, which are positive electrode active materials for lithium ion secondary batteries.
• Lithium-ion secondary batteries are used in a variety of applications, including as power sources for mobile devices such as laptops and mobile phones, and for power tools, and their use is expected to continue to expand in the future in light of the need to build a low-carbon society and promote energy security.
• LiCoO2 which has been used as a positive electrode active material for lithium-ion secondary batteries and is mainly composed of cobalt (Co), a rare metal .
• Li-Ni-Co-Mn-based composite metal oxides and Li-Ni-Co-Al-based composite metal oxides have been proposed as positive electrode active materials to replace LiCoO 2.
• the use of these composite metal oxides as positive electrode active materials for lithium ion secondary batteries has been considered, and their practical application has already progressed.
• caustic soda and ammonia are used as auxiliary raw materials required for producing a composite metal oxide that serves as a positive electrode active material for a lithium ion secondary battery.
• the above-mentioned positive electrode active material that can be used as a positive electrode material for a lithium ion secondary battery to produce a non-electrolyte lithium ion secondary battery with a high capacity and excellent charge/discharge retention rate, and a method for producing the same have been proposed (for example, Patent Document 1).
• the method for producing a Li-Ni-Co-Al composite metal oxide described in Patent Document 1 is characterized in that an aqueous solution of a nickel compound and a cobalt compound is stirred under a nitrogen gas atmosphere while an alkali is added to produce a coprecipitated hydroxide of nickel and cobalt, the coprecipitated hydroxide is dehydrated and dried, and then the coprecipitated hydroxide is dry-mixed with a lithium compound and an aluminum compound, and the mixture is fired under an oxidizing atmosphere.
• the method for producing a positive electrode active material for a non-aqueous electrolyte lithium ion secondary battery described in Patent Document 1 consumes large amounts of auxiliary raw materials such as caustic soda and ammonia due to the increasing demand for Li-Ni-Co-Al and Li-Ni-Co-Mn positive electrode active materials, as described in the examples.
• caustic soda is produced by electrolysis of sodium chloride.
• the electrolysis of sodium chloride requires a huge amount of power. Therefore, a huge amount of power is required to produce caustic soda.
• caustic soda which is a secondary raw material for Li-Ni-Co-Mn and Li-Ni-Co-Al composite metal oxides.
• ammonia is also a substance that causes water pollution. The amount of ammonia discharged is strictly controlled.
• the present invention aims to solve the above problems by providing a method for producing a composite metal oxide, which is a positive electrode active material for lithium ion secondary batteries that exhibits excellent battery characteristics, without using caustic soda or ammonia as auxiliary raw materials for Li-Ni-Co-Mn and Li-Ni-Co-Al composite metal oxides, which are positive electrode active materials for lithium ion secondary batteries.
• the present invention aims to provide a method for producing a composite metal oxide that has excellent performance as a positive electrode active material for lithium ion secondary batteries.
• a method for producing a positive electrode active material for a lithium ion secondary battery comprising: a first step of mixing a raw material containing a complex sulfate compound with an auxiliary raw material containing at least one selected from an alkali metal salt and an alkaline earth metal salt to obtain a complex salt mixture; and a second step of heat-treating the complex salt mixture to obtain a complex metal oxide.
• sulfate compound is a composite sulfate or a sulfate represented by the following general formula (1), and the sulfate is one or more selected from NiSO4 , CoSO4 , MnSO4 , Al2 ( SO4 ) 3 , MgSO4 , and Zr( SO4 ) 2 .
• the present invention provides a method for producing a positive electrode active material for lithium ion secondary batteries that exhibits excellent battery characteristics without using caustic soda or ammonia as secondary raw materials for the Li-Ni-Co-Mn and Li-Ni-Co-Al composite metal oxides that are positive electrode active materials for lithium ion secondary batteries.
• 1 is a 1500-times magnified electron microscope photograph of a composite metal oxide suitable as a raw material for a positive electrode active material for a lithium secondary battery obtained in Example 1.
• 1 is a 5000-times magnified electron microscope photograph of a composite metal oxide suitable as a raw material for a positive electrode active material for a lithium secondary battery obtained in Example 1.
• 1 is a 20,000-times magnified electron microscope photograph of a composite metal oxide suitable as a raw material for a positive electrode active material for a lithium secondary battery obtained in Example 1.
• 1 is a 1500-times magnified electron microscope photograph of the positive electrode active material for a lithium secondary battery obtained in Example 1.
• 2 is an electron microscope photograph at a magnification of 5000 times of the positive electrode active material for a lithium secondary battery obtained in Example 1.
• Example 2 is an electron microscope photograph at a magnification of 20,000 times of the positive electrode active material for a lithium secondary battery obtained in Example 1.
• 1 is a graph showing the discharge capacity retention rate (cycle characteristics) versus cycle number obtained in Example 1 and Comparative Example 1, where (A) is the cycle characteristics obtained in Example 1, and (B) is the cycle characteristics obtained in Comparative Example 1. The rate characteristics obtained in Example 1 and Comparative Example 1 are shown, where (A-0.1C) is the discharge capacity at 0.1C rate obtained in Example 1, (A-4C) is the discharge capacity at 4C rate obtained in Example 1, (B-0.1C) is the discharge capacity at 0.1C rate obtained in Comparative Example 1, and (B-4C) is the discharge capacity at 4C rate obtained in Comparative Example 1.
• a method for producing a positive electrode active material for a lithium ion secondary battery according to the first embodiment will be described. That is, the method for producing a positive electrode active material for a lithium ion secondary battery according to the present embodiment is characterized by including a first step of mixing a raw material containing a composite sulfate compound with an auxiliary raw material containing at least one selected from an alkali metal salt and an alkaline earth metal salt to obtain a composite salt mixture, and a second step of heat-treating the composite salt mixture to obtain a composite metal oxide.
• a first step of mixing a raw material containing a composite sulfate compound with an auxiliary raw material containing at least one selected from an alkali metal salt and an alkaline earth metal salt to obtain a composite salt mixture
• auxiliary raw material containing at least one selected from an alkali metal salt and an alkaline earth metal salt
• the method for producing a positive electrode active material for a lithium ion secondary battery can provide the effect of reducing the amount of caustic soda used, and is characterized by including a step of mixing a raw material consisting of a complex sulfate compound with a sub-raw material consisting of an alkali metal salt or an alkaline earth metal salt to obtain a complex salt mixture, and a step of heat-treating the complex salt mixture to obtain an intermediate containing a complex metal oxide.
• the method for producing a positive electrode active material for a lithium ion secondary battery includes a first step of mixing a raw material containing a composite sulfate compound with an auxiliary raw material containing at least one selected from an alkali metal salt and an alkaline earth metal salt to obtain a composite salt mixture.
• the first step is a step of mixing a raw material for the composite salt mixture, which is a precursor of a composite metal oxide, with the auxiliary raw material to obtain a composite salt mixture.
• the composite sulfate compound refers to a compound including a mixture of sulfate compounds such as NiSO4 , CoSO4 , MnSO4 , and Al2 ( SO4 ) 3 at the molecular level, or a mixed powder of one or more selected from the sulfate compounds.
• the sulfate compound refers to a compound in which sulfate compounds such as NiSO4 , CoSO4 , MnSO4 , and Al2 (SO4) 3 are in individual states.
• the complex salt mixture obtained in the first step is composed of raw material powder and auxiliary raw material powder.
• the raw material powder is a complex sulfate compound or a mixture of sulfate compounds. That is, the raw material of the complex salt mixture contains sulfate ions.
• the complex sulfate compound or a compound containing sulfate is represented by the following general formula (1). [Chemical formula 1] Ni 1-xy -C x -M y -SO 4 ⁇ nH 2 O (1) (0.1 ⁇ x ⁇ 0.33, 0.1 ⁇ y ⁇ 0.33, 0.0 ⁇ n ⁇ 7.0, M is one metal element selected from Mn, Al, Mg, and Zr.) It will be.)
• the composite sulfate is a composite metal sulfate containing nickel, cobalt, and metal M, or a composite metal sulfate hydrate.
• the metal M constituting the composite metal sulfate is a metal that can form a compound with nickel and cobalt, and is one element selected from Mn, Al, Mg, and Zr. From the viewpoint of chemical stability of the composite metal sulfate, the metal M constituting the composite metal sulfate is preferably Mn or Al.
• x is preferably 0.1 to 0.33. If x is in the above range, it is possible to reduce the amount of Co used, which is a rare metal, and to achieve both battery performance during battery production, which is preferable.
• y is preferably 0.1 to 0.33. If y is in the above range, it is possible to achieve both discharge capacity and cycle characteristics during battery production, which is preferable.
• the composite sulfate may be either anhydrous or hydrated. That is, in the above general formula (1), n is preferably 0 to 7.0. If n is within the above range, it is preferable because it is possible to prevent the composite salt mixture from undergoing a chemical reaction due to moisture in the air before the second step described below.
• the composite sulfates are Ni0.86Co0.10Al0.04SO4 , Ni0.86Co0.10Al0.04SO4.2H2O , Ni0.86Co0.10Al0.04SO4.5H2O , Ni0.86Co0.10Al0.04SO4.6.5H2O , Ni0.87Co0.10Al0.03SO4 , Ni0.87Co0.10Al0.03SO4.2H2O , Ni0.87Co0.10Al0.03SO4.5H2O , Ni0.87Co 0.10 Al 0.03 SO 4 ⁇ 6.5H 2 O, Ni 0.80 Co 0.10 Mn 0.10 SO 4 , Ni 0.80 Co 0.10 Mn 0.10 SO 4 ⁇ 2H 2 O, Ni 0.80 Co 0.10 Mn 0.10 SO 4 ⁇ 5H 2 O, Ni 0.80 Co 0.10 Mn 0.10 SO 4 ⁇ 6.5H 2 O, Ni 0.50 Co 0.20 Mn 0.30 SO 4 , Ni 0.50 Co 0.20 Mn 0.30 SO 4 , Ni 0.50 Co 0.20 Mn 0.30 SO 4 , Ni
• Ni0.87Co0.10Al0.03SO4.5H2O and Ni0.80Co0.10Mn0.10SO4.5H2O are preferred from the viewpoint of achieving both discharge capacity and cycle characteristics when these composite sulfate compounds are used as starting materials to form positive electrode active materials by the process described below .
• the sulfate compound constituting the composite sulfate compound is one or more sulfate compounds selected from NiSO4, CoSO4 , MnSO4 , Al2 ( SO4 ) 3 , MgSO4 and Zr( SO4 ) 2 .
• the sulfate compound is composed of a metal element and sulfate ions.
• the composite sulfate compound may be a single sulfate compound selected from NiSO4 , CoSO4 , MnSO4 , Al2 ( SO4 ) 3 , MgSO4 and Zr( SO4 ) 2 , or a compound obtained by dry mixing two or more kinds of sulfate compounds selected from these sulfate compounds, or a compound obtained by wet mixing and recrystallizing two or more kinds of sulfate compounds selected from these sulfate compounds. Specifically, a composite sulfate compound obtained by wet mixing and recrystallizing three kinds of sulfate compounds consisting of NiSO4 , CoSO4 and MnSO4 or Al2 ( SO4 ) 3 is preferred.
• the means for obtaining the crystals of the composite sulfate compound is not particularly limited, but examples thereof include a method for obtaining a composite sulfate compound by dry mixing two or more sulfate compounds selected from Ni, Co, Mn, Al, Mg, and Zr to obtain a mixed sulfate compound, a method for obtaining a composite sulfate compound by adding sulfuric acid to two or more metals or alloys selected from Ni, Co, Mn, Al, Mg, and Zr, and a method for obtaining a composite sulfate compound by adding sulfuric acid to two or more metal oxides, hydroxides, or carbonates selected from Ni, Co, Mn, Al, Mg, and Zr.
• the means for obtaining crystals of the composite sulfate compound is not particularly specified, but preferably includes preparing an aqueous solution of one or more sulfate compounds selected from NiSO4 , CoSO4 , MnSO4 , Al2 ( SO4 ) 3 , MgSO4 , and Zr( SO4 ) 2 , mixing them in a wet state, and then recrystallizing them by supersaturation through removal of moisture, etc.
• the average particle size (D50) r1 of the sulfate compounds constituting the composite sulfate compounds and mixed sulfate compounds is preferably 10 to 1000 ⁇ m, although it depends on the conditions of the implementation of the crushing process and the like. If the average particle size r1 (D50) of the sulfate compounds constituting the composite sulfate compounds and mixed sulfate compounds is 10 ⁇ m or more, workability during the crushing process can be maintained, and if it is 1000 ⁇ m or less, the reactivity between the raw materials and auxiliary materials can be improved, thereby sufficiently improving the yield of the composite metal oxide, which is preferable.
• the composite salt mixture obtained in the first step contains at least one selected from an alkali metal salt and an alkaline earth metal salt as an auxiliary material.
• the alkali metal ion forming the alkali metal salt is any one selected from Li + , Na +, and K + .
• the alkaline earth metal ion forming the alkaline earth metal salt is any one selected from Be2 + , Mg2 +, and Ca2 + .
• the anion forming the alkali metal salt and the alkaline earth metal salt is any one selected from CO32- , OH- , and O2- .
• the auxiliary material includes at least one selected from an alkali metal salt and an alkaline earth metal salt
• the alkali metal salt and the alkaline earth metal salt can be a carbonate, hydroxide, or oxide of one or more elements selected from Li, Na, K, Be, Mg, and Ca.
• auxiliary materials are thus alkali metal salts and alkaline earth metal salts
• auxiliary materials are thus alkali metal salts and alkaline earth metal salts
• sulfate ions are released from the sulfate compound and form sulfate salts with the alkali metal ions constituting the alkali metal salt or the alkaline earth metal ions constituting the alkaline earth metal salt, which are the auxiliary materials, which is preferable.
• the alkali metal salt used as the auxiliary raw material is preferably Na2CO3 , which has high reactivity with the raw material composite sulfate compound or the sulfate compounds constituting it, and can reduce raw material costs.
• the alkaline earth metal salt used as the auxiliary raw material is preferably CaCO3 , which has high reactivity with the raw material composite sulfate compound or the sulfate compounds, and can reduce raw material costs.
• the average particle size (D50) r2 of the alkali metal salts and alkaline earth metal salts is not particularly specified, but is preferably 10 to 1000 ⁇ m depending on the conditions of the implementation of the crushing process. If the alkali metal salts and alkaline earth metal salts are 10 ⁇ m or more, the workability of these metal salts during the crushing process is maintained, and if they are 1000 ⁇ m or less, the reactivity between the raw materials and auxiliary materials is improved, and the yield of the composite metal oxide can be sufficiently improved.
• the first step is a step of obtaining a composite salt mixture by dry or wet mixing of a composite sulfate compound as a raw material and an alkali metal salt or an alkaline earth metal salt as a secondary raw material.
• the mixing of the composite sulfate and the mixed sulfate compound as raw materials in the first step is performed by setting the average particle size of the particles constituting the composite sulfate compound as a raw material and the average particle size of the particles constituting the alkali metal salt or the alkaline earth metal salt as a secondary raw material within a predetermined range.
• the average particle size (D50) r1 of the raw material composite sulfate compound and sulfate compound is set in the range of 10 to 1000 ⁇ m. Furthermore, the average particle size (D50) r2 of the particles constituting the auxiliary raw material alkali metal salt or alkaline earth metal salt is set in the range of 10 to 1000 ⁇ m.
• the shape of particles of a Li-Ni-Co-Al or Li-Ni-Co-Mn based positive electrode active material for a lithium ion secondary battery is controlled by controlling crystallization using caustic soda and ammonia in the production process of a composite metal hydroxide, which is its precursor.
• caustic soda is mainly produced by electrolysis of sodium chloride, and the production process requires a large amount of electricity.
• Ammonia is also strictly controlled as a substance of concern that may cause water pollution in rivers. From this technical perspective, we have conducted research and development into a manufacturing technology that reduces the amount of caustic soda and ammonia used, and a manufacturing technology for positive electrode active materials that enables the realization of both high capacity lithium-ion secondary batteries.
• Li-Ni-Co-Al and Li-Ni-Co-Mn based positive electrode active materials that have a high Ni content and are expected to have high capacity, while reducing the amount of caustic soda and not using ammonia at all in the manufacturing process.
• a composite salt mixture that serves as a precursor of the composite metal oxide that is the raw material of the positive electrode active material can be obtained without using any caustic soda or ammonia.
• the composite metal oxide obtained by heat-treating the composite salt mixture is mixed with a lithium compound, and the resulting lithium mixture is fired to form the positive electrode active material for lithium-ion secondary batteries into nano-sized single crystals, making it possible for all particles constituting the positive electrode active material to have a uniform composition and particle size.
• the average particle size of the composite sulfate compound as the raw material and the average particle size of the particles constituting the alkali metal salt or alkaline earth metal salt as the auxiliary material are set within a predetermined range, so that the raw material and the auxiliary material can be mixed. That is, the composite sulfate compound as the raw material and the particles constituting the alkali metal salt or alkaline earth metal salt as the auxiliary material are appropriately dispersed, and the contact area is increased, so that the reaction between the raw material and the auxiliary material proceeds smoothly.
• the desulfation ion reaction can be advanced and complex metal oxides can be obtained directly at a low temperature below the decomposition temperature of complex sulfate compounds.
• the auxiliary materials alkali metals and alkaline earth metals
• SOx sulfur oxides
• complex metal oxides can be obtained directly without generating SOx (sulfur oxides).
• complex sulfate compounds are heated, they undergo thermal decomposition, releasing SOx and becoming metal oxides.
• a composite salt mixture can be obtained from the raw materials and auxiliary materials without using harmful substances such as ammonia or caustic soda, which requires an excessive amount of electricity for its production, by controlling the average particle size of the particles constituting the raw materials, the composite sulfate and the mixed sulfate compound, and the average particle size of the particles constituting the auxiliary materials, the alkali metal salt or alkaline earth metal salt.
• the average particle size (D50) of the composite salt mixture obtained by mixing the raw materials and auxiliary materials is preferably 10 to 1000 ⁇ m after carrying out a crushing process, etc. If the average particle size (D50) of the composite salt mixture is 10 ⁇ m or more, it is preferable because the workability during the crushing process of the composite salt mixture can be maintained, and if it is 1000 ⁇ m or less, it is preferable because the reactivity between the raw materials and the auxiliary materials is improved and the yield of the composite metal oxide can be sufficiently improved. In other words, the smaller the average particle size of both the raw materials and the auxiliary materials, the higher the reactivity during heat treatment, and the greater the effect of improving the yield and reducing impurities, which is preferable.
• the contact area between the particles constituting the raw material and the particles constituting the auxiliary material can be made as large as possible, which increases the reactivity in the second step described below, thereby improving the yield and reducing impurities.
• the mixing ratio of the sulfate compound, which is the raw material contained in the complex salt mixture, and the alkali metal salt or alkaline earth metal salt, which is the auxiliary raw material is not particularly limited as long as it is within a range that can sufficiently improve the yield of the complex metal oxide, but it may be determined, for example, as follows, taking into account the relationship between the substance amount of sulfate ions that make up the sulfate compound and the substance amount of cations that make up the alkali metal salt or alkaline earth metal salt.
• the mixing ratio of the sulfate compound as the raw material and the alkali metal salt as the auxiliary raw material can be set as shown in the following relational formula (1), where the amount of substance of sulfate ions ( SO4 2- ) contained in the sulfate compound is ⁇ SO4 (mol) and the amount of substance of alkali metal ions constituting the alkali metal salt is ⁇ M+ (mol).
• ⁇ SO4 is the amount of substance of sulfate ions contained in the sulfate compound
• ⁇ M+ is the amount of substance of alkali metal ions constituting the alkali metal salt
• M + is one element selected from Li, Na, and K.
• the mixing ratio of the raw material sulfate compound and the auxiliary raw material alkaline earth metal salt can be set as shown in the following relational formula (2), where the amount of substance of sulfate ions ( SO4 2- ) contained in the sulfate compound is ⁇ SO4 (mol) and the amount of substance of alkali metal ions constituting the alkaline earth metal salt is ⁇ M2 + (mol).
• ⁇ SO4 is the amount of substance of sulfate ions contained in the sulfate compound
• ⁇ M2+ is the amount of substance of alkali metal ions constituting the alkali metal salt
• ⁇ M2+ is one element selected from Be, Mg, and Ca.
• the method for producing a positive electrode active material for a lithium ion secondary battery according to the present embodiment includes a second step of obtaining a composite metal oxide by heat-treating the composite salt mixture.
• the second step is a step of obtaining a composite metal oxide that is a raw material for the positive electrode active material for a lithium ion secondary battery.
• the conditions for heat treating the complex salt mixture in the second step are to heat the complex salt mixture at 200°C to 800°C, preferably at 640°C.
• the type of heating furnace used in the second step is not particularly specified, but examples include continuous firing furnaces such as rotary kilns and roller hearth kilns, and batch firing furnaces such as lifting and square cart types.
• the heating time is not particularly specified as long as it is in the range of 1 to 10 hours, but is preferably 3 hours.
• the heating atmosphere is not particularly specified, but is preferably air.
• the composite metal oxide obtained by heat-treating the composite salt mixture under predetermined heating conditions is preferably Ni1- xyCoxMyO (0.1 ⁇ x ⁇ 0.33, 0.1 ⁇ y ⁇ 0.33, M is one or more elements selected from Mn, Al, Mg, and Zr).
• the composite metal oxide obtained in the second step contains, as a by-product, a sulfate compound of an alkali metal or an alkaline earth metal (one or more compounds selected from Li2SO4 , Na2SO4 , K2SO4 , BeSO4 , MgSO4, and CaSO4 ) .
• a sulfate compound of an alkali metal or an alkaline earth metal one or more compounds selected from Li2SO4 , Na2SO4 , K2SO4 , BeSO4 , MgSO4, and CaSO4 .
• a drying step is preferably carried out by heating at 200°C or higher.
• the method for producing a positive electrode active material for a lithium ion secondary battery according to the present embodiment includes a third step of mixing a composite metal oxide and a lithium compound to obtain a lithium mixture.
• the third step is a step of obtaining a lithium mixture that is a precursor of the positive electrode active material for a lithium ion secondary battery.
• examples of the lithium compound to be mixed with the composite metal oxide include LiOH.H2O , LiOH, and Li2CO3 , but it is preferable to use LiOH.
• LiOH LiOH
• lithium ions in the lithium compound are added to the composite metal oxide during firing in the fourth step described below.
• the composite metal oxide and the lithium compound may be mixed by wet mixing or dry mixing. Dry mixing is preferably carried out for about 0.05 to 1.5 hours under normal temperature and pressure conditions in a closed state (e.g., with the raw material inlet of the powder mixer closed).
• the method for producing a positive electrode active material for a lithium ion secondary battery according to the present embodiment includes a fourth step of calcining a lithium mixture to obtain a positive electrode active material for a lithium ion secondary battery.
• the fourth step is a step of obtaining a positive electrode active material for a lithium ion secondary battery.
• the composite metal oxide obtained in the second step is suitable as a raw material for lithium ion secondary batteries. Furthermore, in the third step, the composite metal oxide obtained in the second step is mixed with a lithium compound to obtain a lithium mixture. Then, in the fourth step, the lithium mixture obtained in the third step is fired to obtain a positive electrode active material for lithium ion secondary batteries.
• the method for producing a positive electrode active material for a lithium ion secondary battery according to this embodiment is carried out by carrying out a fourth step of calcining the lithium mixture obtained in the third step.
• the raw material mixture prepared as described above is calcined in an oxidizing atmosphere at 700 to 800°C for 5 to 20 hours.
• the mixture is rapidly cooled outside the calcination furnace or slowly cooled in the furnace.
• the heating conditions when calcining the lithium mixture are not particularly limited, but the temperature is raised for, for example, 5 to 15 hours, preferably 8 to 12 hours, from the start of heating the furnace.
• the method for producing a positive electrode active material for a lithium ion secondary battery according to this embodiment includes the first to fourth steps, and thereby makes it possible to produce a positive electrode active material for a lithium ion secondary battery.
• Ammonia and caustic soda are used in conventional manufacturing methods for positive electrode active materials for lithium ion secondary batteries (currently the most mainstream wet manufacturing process).
• Caustic soda is used to generate metal hydroxide particles made of Ni and other elements in an aqueous solution, which are the raw material for the positive electrode active material, and ammonia is also used to control the average particle size and particle shape.
• the manufacturing method for positive electrode active materials for lithium ion secondary batteries according to this embodiment controls the average particle size of the raw materials and the average particle size of the auxiliary materials, and produces a composite salt mixture with a controlled average particle size, making it possible to produce positive electrode active materials for lithium ion secondary batteries without using ammonia or caustic soda.
• Example 1 Provide and analysis of complex sulfate compounds> A mixed aqueous solution of sulfate compounds was prepared by dissolving 483.08 g of commercially available NiSO 4 .7H 2 O, 56.22 g of commercially available CoSO 4 .7H 2 O, and 13.68 g of commercially available Al 2 (SO 4 ) 3 in 1100 mL of pure water.
• the aqueous solution of the sulfate compound was concentrated at 80 ° C using an evaporator to remove water, yielding Ni0.86Co0.1Al0.04SO4.6.5H2O crystals.
• the molar ratio of Ni:Co:Al ratio of gram atoms of each element was measured using an inductively coupled plasma (ICP) optical emission spectrometer (manufactured by Thermo Fisher Scientific, Inc., product name " ICAP6500 ").
• the amount of water of hydration was calculated using a simultaneous differential thermal-thermogravimetric analyzer (manufactured by Rigaku Corporation, product name TG-DTA8122).
• Ni0.86Co0.1Al0.04SO4.6.5H2O crystal was pulverized in a mortar to obtain Ni0.86Co0.1Al0.04SO4.6.5H2O crystal having a D50 of 72 ⁇ m , which was used as a raw material .
• Na2CO3 was pulverized in a mortar to prepare Na2CO3 crystals with a D50 of 70 ⁇ m .
• 500 g of the Ni0.86Co0.1Al0.04SO4.6.5H2O crystals and 234 g of Na2CO3 crystals were dry-mixed in a nylon plastic bag for 5 minutes while being kneaded, to obtain a composite salt mixture.
• An electrode foil was made using the positive electrode active material obtained as described above.
• the positive electrode active material, conductive additive, binder, and dispersion medium were mixed in a ratio of 45:2.5:2.5:50.
• Denka Black manufactured by Denka was used as the conductive additive, and Solef5130 manufactured by Solvay Japan was used as the binder and dispersion medium.
• Mixing was performed at 6000 rpm for 5 minutes using a homodisper manufactured by Primix to form a paste.
• This paste was applied to an aluminum foil in a thickness of 10 mils using the doctor blade method.
• the applied electrode foil was heated on a hot plate at 110°C for 4 hours, the NMP was removed, and a roll press was performed at 0.04 mm to obtain a positive electrode foil.
• a lithium ion secondary battery was fabricated using the obtained electrode foil.
• the fabricated battery was composed of a positive electrode, a separator (glass fiber filter paper), a metallic lithium negative electrode, and an electrolyte (1 mol/L LiPF 6 /PC), and was fabricated in an argon atmosphere.
• This battery was repeatedly charged and discharged 80 times at a measurement temperature of 20°C, a voltage range of 4.25 to 2.5 V, and a voltage rate of 1 C, and the cycle characteristics (discharge capacity for each cycle and discharge capacity retention rate) were evaluated.
• the rate characteristic test was performed at a voltage range of 4.25 to 2.5 V and a voltage rate of 0.1 C to 5 C.
• Figures 3 and 4 show the results of measuring the cycle characteristics (discharge capacity for each cycle or the rate of capacity loss for each cycle relative to the discharge capacity at the initial discharge) and rate characteristics during charge and discharge of the lithium-ion secondary battery obtained in Example 1.
• the ⁇ marks in Figure 3 represent data for Example 1.
• the solid line A represents data for Example 1.
• Example 2 ⁇ Production and analysis of complex sulfate compounds> A mixed aqueous solution of sulfate compounds was prepared by dissolving 483.08 g of commercially available NiSO 4 .7H 2 O, 51.66 g of commercially available CoSO 4 .7H 2 O, and 41.00 g of commercially available MnSO 4 .7H 2 O in 1300 mL of pure water.
• the aqueous solution of the sulfate compound was concentrated at 80 ° C using an evaporator to remove water, yielding Ni0.80Co0.1Mn0.1SO4.6.5H2O crystals.
• the molar ratio of Ni: Co :Mn ratio of gram atoms of each element was measured using an inductively coupled plasma (ICP) optical emission spectrometer (manufactured by Thermo Fisher Scientific, Inc., product name " ICAP6500 ").
• the amount of water of hydration was calculated using a simultaneous differential thermal and thermogravimetric analyzer (manufactured by Rigaku Corporation, product name TG-DTA8122).
• Ni0.80Co0.1Mn0.1SO4.6.5H2O crystals were pulverized in a mortar to obtain Ni0.80Co0.1Mn0.1SO4.6.5H2O crystals having a D50 of 72 ⁇ m as a raw material.
• Commercially available Na2CO3 was pulverized in a mortar to obtain Na2CO3 crystals having a D50 of 70 ⁇ m.
• An electrode foil which is a positive electrode of a lithium ion secondary battery, and a lithium ion secondary battery equipped with the same were produced in the same manner as in Example 1, except that the positive electrode active material obtained as described above was used.
• Example 1 (same as Example 1 of WO2016-143844A1) A Ni-Co aqueous solution was prepared at room temperature with a molar ratio of Ni:Co between NiSO4 and CoSO4 of 89:11. Meanwhile, pure water was placed in a SUS reaction tank (capacity 50 L) with a lid and an overflow port, and the agitator was operated at 60°C. While maintaining this state, N2 gas was introduced, and the Ni-Co aqueous solution, ( NH4 ) 2SO4 , and NaOH aqueous solution were dropped, and stirring was continued for 10 hours at a tip speed of 4.1 m/s.
• 950g (molar ratio 0.97) of the Ni-Co coprecipitated hydroxide, 160g (molar ratio 0.03) of alumina (average particle size: 10 ⁇ m), and 445g (molar ratio 1.03) of pulverized lithium hydroxide monohydrate (D50: 30 ⁇ m) were dry mixed in a blender for 1 hour. After mixing, the raw material powders of the Ni-Co coprecipitated hydroxide, alumina, and lithium hydroxide were sintered in an oxidizing atmosphere at 750°C for 20 hours, including the heating time, in an electric furnace.
• the raw material was taken out of the furnace when the temperature inside the furnace reached 200°C, and was allowed to cool to room temperature, and a positive electrode active material for lithium ion secondary batteries was obtained. It was found that the positive electrode active material for lithium ion secondary batteries was a positive electrode active material in the form of approximately spherical secondary particles.
• an electrode foil which is a positive electrode of a lithium ion secondary battery, was prepared in the same manner as in Example 1. Furthermore, a lithium ion secondary battery was prepared using this electrode foil.
• the initial capacity (discharge capacity), discharge capacity retention rate, i.e., cycle characteristics (the ratio of discharge capacity after 80 discharges to the discharge capacity at the initial discharge), and rate characteristics of this battery were measured under the same conditions as in Example 1, and the results are shown in Table 1 and Figures 3 and 4. In Figure 3, circles represent data for Comparative Example 1, and the dashed line in Figure 4 (B) represents data for Comparative Example 1.
• the lithium ion secondary battery obtained from the positive electrode active material of Example 1 has superior cycle characteristics compared to the lithium ion secondary battery obtained from the positive electrode active material of Comparative Example 1. From Figure 4, it can be seen that the lithium ion secondary battery obtained from the positive electrode active material of Example 1 has superior initial capacity and high rate characteristics of 4C or more compared to the lithium ion secondary battery obtained from the positive electrode active material of Comparative Example 1.
• the positive electrode active material for lithium ion secondary batteries manufactured by the manufacturing method for a positive electrode active material for lithium ion secondary batteries according to the present invention has excellent cycle characteristics because the particles constituting the positive electrode material are single-crystalline primary particles, and therefore crack generation due to volume change caused by repeated charging and discharging is suppressed. Furthermore, the positive electrode active material for lithium ion secondary batteries manufactured by the manufacturing method for a positive electrode active material for lithium ion secondary batteries according to the present invention has an extremely small particle size of 30 nm compared to conventional products in which the particle size of the particles constituting the positive electrode material is about 10 ⁇ m. Therefore, the positive electrode active material for lithium ion secondary batteries produced by the method for producing a positive electrode active material for lithium ion secondary batteries according to the present invention has a large surface area and can rapidly insert and remove Li ions.
• the technology of the present invention can significantly reduce or eliminate the use of caustic soda and ammonia in the manufacturing process of positive electrode active material for lithium ion secondary batteries, and is expected to reduce the environmental impact associated with the manufacture of positive electrode active material for lithium ion secondary batteries.
• the positive electrode active material for lithium secondary batteries manufactured by the manufacturing technology of the present invention can be used for a variety of well-known applications that require high capacity at all times, including power sources for EVs, personal computers, mobile phones, and backup power sources, and is therefore industrially useful.

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• 2023
  • 2023-07-13 JP JP2025532347A patent/JPWO2025013281A1/ja active Pending
  • 2023-07-13 WO PCT/JP2023/025883 patent/WO2025013281A1/ja active Pending

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