TW201341319A - Mixed oxide comprising the elements lithium, nickel, cobalt and manganese, and process for preparation thereof - Google Patents

Abstract

Mixed oxide having the composition Lix Nia Cob Mnc O2 where 0.8 ≤ x ≤ 1.2, 0.3 ≤ a ≤ 0.6, 0.1 ≤ b ≤ 0.4, c =1 - a - b and a BET surface area of 5 to 30 m<SP>2</SP>/g. Mixed oxide having the composition Lix Nia Cob Mnc O2 where (a) 0.8 ≤ x ≤ 1.2; 0.3 ≤ a ≤ 0.6; 0.1 ≤ b ≤ 0.4; c= 1 - a - b, (b) a BET surface area of 2 m<SP>2</SP>/g to less than 5 m<SP>2</SP>/g, (c) a ratio of the intensities of the signals at 2 Θ = 18.6 ± 1 DEG relative to 2 Θ = 44.1 ± 1 DEG in the x-ray diffractogram of at least 1.65.

Description

a mixed oxide containing lithium, nickel, cobalt and manganese elements and a method for producing the same

The present invention relates to a mixed oxide containing lithium, nickel, cobalt and manganese elements, a process for producing the same, and a secondary battery comprising the mixed oxide.

EP-A-9441125 discloses a powder having the composition Li _a Co _b Mn _c Ni _1-bc O ₂ , wherein 0 a 1.2, 0.01 b 0.4,0.01 c 0.4 and 0.02 b+c 0.5 having an average particle size of from 3 to 30 μm, wherein 10% of the particles have an average particle diameter of less than 1 μm, and have a BET surface area of from 0.15 to 2 m ² /g. The powder was obtained by heat-treating a mixture of a hydroxide of lithium, cobalt and nickel and manganese dioxide at a temperature of 750 ° C for 20 hours and then grinding the resulting mixture.

EP-A-1295851 discloses a powder consisting of Li _1+x+α Ni _(1-x-y+δ)/2 Mn _(1-xy-δ)/2 Co _y O ₂ , wherein 0 x 0.05;-0.05 x+α 0.05;0 y 0.4; if 0 y 0.2, then -0.1 δ 0.1; or if 0.2<y 0.4, then -0.24 δ 0.24. These powders are shown in the x-ray diffraction pattern: lithium nitrate is known to have a layer structure from a line having an angle of 2 于 at an angle of about 18° (I ₍₀₀₃₎ ) and about 44° (I ₍₁₀₄₎ ). When 0 y At 0.2, the line intensity ratio I ₍₀₀₃₎ /I ₍₁₀₄₎ is 0.83 to 1.11 and when 0.2 < y At 0.4, the line intensity ratio I ₍₀₀₃₎ / I ₍₁₀₄₎ is 1 to 1.43.

EP-B-1390994 discloses a mixed oxide as a cathode composition for a lithium ion battery and represented by the formula Li(Ni _y Co _1-2y Mn _y )O ₂ , wherein 0.167 < y < 0.5, the composition It is in the form of a single phase with a 03 crystal structure that does not undergo any phase transition to the spinel crystal structure when introduced into a lithium ion battery, and undergoes 100 full charge/discharge cycles and 30 mA at 30 °C. The discharge current of /g has a final capacitance of 130 mAh/g.

EP-A-1391950 discloses a mixed oxide having a composition of Li _x Mn _0.5-a Ni _0.5-b O ₂ as a positive electrode material, wherein 0 < x < 1.3, 0.05 < a < 0.3, 0.05 b<0.3,0.1 Ab 0.02 and a+b<0.5, which have a BET surface area of 0.3 to 1.6 m ² /g and a line intensity ratio I ₍₀₀₃₎ /I _{(104) of} 0.95 to 1.54.

In Trans. Nonferrous Met. Soc. China 17 (2007) 897-901, Li et al. disclose a mixed oxide powder having a composition of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , which has a maximum of 1.62. Line intensity ratio I ₍₀₀₃₎ /I ₍₁₀₄₎ .

In Int. J. Electrochem. Sci. 2 (2007) 689-699, Periasamy et al. disclose a mixed oxide powder having a composition of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ having a maximum of 1.347. Line intensity ratio I ₍₀₀₃₎ /I ₍₁₀₄₎ .

In Asia-Pac. J. Chem. Eng. 3 (2008) 527-530, Huang et al. disclose a mixed oxide powder having a composition of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ having 1.48. The line intensity ratio I ₍₀₀₃₎ /I ₍₁₀₄₎ .

In Bull. Korean Chem. Soc. 30 (2009) 2603-2607, Jeong et al. disclose a mixed oxide powder having a composition of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ having a maximum spectrum of 1.38. Line strength ratio I ₍₀₀₃₎ /I ₍₁₀₄₎ .

In Int. J. Elektrochem. Sci. 4 (2009) 1770-1778, Rambabu et al. disclose a mixed oxide powder having a composition of Li _1.10 Ni _1/3 Co _1/3 Mn _1/3 O ₂ which has a smaller The spectral intensity ratio of 1.2 is I ₍₀₀₃₎ / I ₍₁₀₄₎ .

The powder is obtained by heat-treating a mixture of a hydroxide of lithium, cobalt and nickel and manganese dioxide, mixing at a temperature of 750 ° C for 20 hours, and then grinding the resulting mixture. The powder can in principle be used as a cathode material for secondary batteries.

The technical problem addressed by the present invention is that materials having at least comparable values compared to the prior art in terms of discharge capacity and discharge cycle.

The present invention provides a mixed oxide having a composition of Li _x Ni _a Co _b Mn _c O ₂ , wherein 0.8 x 1.2, 0.3 a 0.6, 0.1 b 0.4, c = 1 - ab and a BET surface area of 5 to 30 m ² /g, preferably 10 to 20 m ² /g.

This mixed oxide will be referred to as mixed oxide A in the case of the present invention. Mixed oxides are understood to mean an intimate mixture of all mixed oxide components. Therefore, it is very obvious that it is a mixture of atomic grades rather than a physical mixture of oxides. In the context of the present invention, the terms "mixed oxide", "mixed oxide powder" and "mixed oxide particles" are used in an equivalent manner. The mixed oxide particles are usually present in the form of aggregated first-order particles. The BET surface area is determined in accordance with DIN ISO 9277.

The mixed oxide A of the present invention has a value corresponding to 0.8 x 1.2, 0.3 a 0.6, 0.1 b 0.4, c = 1 - ab composition. Within this range are sub-ranges representing mixed oxide A having a particularly high discharge charge.

The first range has a composition including 0.30 < a < 0.40 and 0.30 < b < 0.40. More preferably, a = b = 1/3.

The second range consists of 0.35 a 0.45 and 0.15 b 0.30. More preferably, a = 0.40 and b = 0.20.

The third range consists of 0.35<a 0.55 and 0.15 b 0.30. More preferably, a = 0.50 and b = 0.20.

With respect to each of the mixed oxides A, it is preferably according to 0.98 x The composition of 1.07. More preferably, x=1.

In order to improve the conductivity of the mixed oxide A of the present invention, it has been found that when it comprises, in each case, at least 0.1% by weight of carbon, preferably from 0.1 to 2% by weight, based on the carbon-containing mixed oxide A, It is beneficial. The source of carbon can be the feedstock used to prepare the mixed oxide A and/or the conductive carbon black, graphite or other carbonaceous compound that is controlled to be added during the preparation of the mixed oxide. The carbon atom of the main portion of the mixed oxide A obtained by the production method using the addition of the conductive carbon black according to the present invention is between the first-order particles, and thus is not easily burned during the preparation of the mixed oxide A or its heat treatment. .

It has also been found to be advantageous when the mixed oxide A has a d _{50 of} less than or equal to 10 μm. d _{50 is} derived from the cumulative distribution curve of the volume-average size distribution. This is usually determined by a laser diffraction method. In the case of the present invention, a Cilas 1064 instrument from Cilas is used for this purpose. The d ₅₀ series is understood to mean that 50% of the particles of the mixed oxide A are within the specified size range. The d ₉₀ system is understood to mean that 90% of the particles of the mixed oxide A are within the specified size range. The d ₉₉ is understood to mean that 99% of the particles of the mixed oxide A are within the specified size range. The d ₉₀ of the particles of the mixed oxide A may preferably be from 1 to 10 μm, more preferably from 2 to 5 μm. The d ₉₉ of the particles of the mixed oxide A may preferably be from 3 to 15 μm, more preferably from 4 to 8 μm.

The invention further provides a process for preparing a mixed oxide A, wherein a) atomizing a solution stream with a carrier gas to produce an aerosol, and the solution in each case comprises at least one metal compound from which the metal compound is derived The desired stoichiometric ratio is selected from the group consisting of lithium, nickel, cobalt, and manganese, and b) the aerosol is transferred to a reaction space where the aerosol is passed through a fuel gas and an oxygen-containing gas. The reaction in the flame formed by the reaction, c) introducing an oxygen-containing gas into the flame at at least one additional location, and d) cooling the reaction stream and then separating the solid product from the reaction stream.

Preferably, the amount of oxygen is selected so that 1.05 λ 2. λ is the ratio of oxygen required to total oxygen/combustion fuel gas present. Suitable fuel gases can be hydrogen, methane, ethane, propane, butane, and mixtures thereof. Preferably, hydrogen is used. The oxygen-containing gas used is usually air.

The carrier gas is preferably air, nitrogen and/or water vapor. The ratio of the mass flow rate of the solution / the volume flow rate of the carrier gas [g of the solution / m ³ (STP) of the carrier gas] should be at least 500, preferably from 500 to 3,000, more preferably from 600 to 1,000. An aerosol is formed from a solution containing a metal compound using a carrier gas and a nozzle of two or more substances. The aerosol preferably has an average droplet size of not more than 150 μm, more preferably an average droplet size of 20 to 100 μm.

The concentration of the metal compound in the solution is preferably at least 10% by weight, more preferably from 10 to 20% by weight, based in each case on the metal oxide. It is important in the invention that the metal compound is present in solution. In order to achieve solubility and to achieve an appropriate viscosity for the atomized solution, the solution can be heated. In principle, it is possible to use all oxidizable soluble metal compounds. These may be inorganic metal compounds such as nitrates, chlorides, bromides or organometallic compounds such as alkoxides or carboxylates. The alkoxide used may preferably be ethoxylate, n-propoxide, isopropoxide, n-butoxide and/or tertiary butoxide. The carboxylate used may be acetic acid, propionic acid, butyric acid, caproic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, octanoic acid, 2-ethylhexanoic acid, valeric acid, A compound based on citric acid and/or lauric acid. It is particularly advantageous to use 2-ethylhexanoates or laurates. The solution may comprise one or more inorganic metal compounds, one or more organometallic compounds or a mixture of inorganic and organometallic compounds.

The solvent is preferably selected from the group consisting of water, C ₅ -C ₂₀ -alkanes, C ₁ -C ₁₅ -alkanocarboxylic acids and/or C ₁ -C ₁₅ -alcohols. More preferably, water or a mixture of water and an organic solvent may be used.

The organic solvent to be used, or the component of the organic solvent mixture used, may preferably be an alcohol such as methanol, ethanol, n-propanol, isopropanol, n-butanol or tertiary butanol, or a glycol such as B. Glycol, pentanediol, 2-methyl-2,4-pentanediol, C ₁ -C ₁₂ -carboxylic acids such as acetic acid, propionic acid, butyric acid, caproic acid, oxalic acid, malonic acid, succinic acid, pentane Diacid, adipic acid, octanoic acid, 2-ethylhexanoic acid, valeric acid, citric acid, lauric acid. It is also possible to use benzene, toluene, naphtha and/or petroleum spirit.

In addition, it has been found that, in terms of the amount of electricity to be achieved and the charge/discharge cycle, a particularly good mixed oxide A for a secondary battery can be obtained when: - a high average exit velocity of the aerosol entering the reaction space Preferably, it is at least 50 ms ^-1 , more preferably from 100 to 300 ms ^-1 , and/or - a low average velocity of the reaction mixture in the reaction space, preferably from 0.1 ms ^-1 to 10 ms ^-1 , more preferably It is 1 to 5 ms ^-1 .

In a particular embodiment, conductive carbon black, graphite or another carbon-containing compound is introduced into the reaction space and/or flame. In this case, it is possible to use carbon black or a dispersion containing carbon black. The amount of carbon black or graphite is preferably from 0.1 to 2% by weight based on C (based on the metal compound (calculated as mixed oxide)). Examples of suitable conductive carbon blacks include Printex L or acetylene blacks such as Ketjenblack and Denka Black.

The present invention further provides a mixed oxide having a composition of Li _x Ni _a Co _b Mn _c O ₂ wherein a) 0.8 x 1.2;0.3 a 0.6; 0.1 b 0.4; c = 1 - ab, b) BET surface area from 2 m ² /g to less than 5 m ² /g, preferably from 2.5 to 4 m ² /g, c) in the x-ray diffraction pattern at 2 Θ = The ratio of the intensity of the line of 18.6 ± 1 ° with respect to the line of 2 Θ = 44.1 ± 1 ° is at least 1.65, preferably from 1.65 to 2.30, more preferably from 1.70 to 2.00.

This mixed oxide will be referred to as mixed oxide B in the case of the present invention. Wherein the mixed oxide B is mixed with oxide A with higher crystallinity different.

As in the case of the mixed oxide A, in the case of the mixed oxide B, it also has a subrange representing the composition of the extremely high discharge electric quantity.

The first range has a composition including 0.30 < a < 0.40 and 0.30 < b < 0.40. More preferably, a = b = 1/3.

The second range consists of 0.35 a 0.45 and 0.15 b 0.30. More preferably, a = 0.40 and b = 0.20.

The third range consists of 0.35<a 0.55 and 0.15 b 0.30. More preferably, a = 0.50 and b = 0.20.

With respect to each of the mixed oxides B, it is preferably according to 0.98 x The composition of 1.07. More preferably, x=1.

The mixed oxide B is characterized by a ratio of the intensity of the line at 2Θ=18.6±1° to the line at 2Θ=44.1±1° of at least 1.65. The x-ray data is a PANanalytical X'Pert PRO diffractometer using Cu-K _alpha radiation at a scan rate of 10 100 (2θ) at a range of 0.017 °/step, with a measurement time of 80 sec/step, corresponding to 0.0265 ° / sec. Evaluation was performed using the Rietveld refinement method.

Mixed oxide B, measured by X'Pert Data Viewer software, at 2Θ=18.6±1°, preferably having a full-width half-peak amplitude of the line >0.20 to 0.40 (preferably 0.22 to 0.32), and at 2Θ= 44.1 ± 1 ° has 0.25 to 0.40 (preferably 0.27 to 0.35).

Further, the mixed oxide B preferably exhibits a hexagonal lattice structure having a space group of R3m. Regarding the mixed oxide B constituting a = b = c = 1/3, preferably, 1.650 c/3a 1.660. Regarding the mixed oxide B constituting a = 0.5, b = 0.2, and c = 0.3, preferably, 1.662 c/3a 1.750.

The d ₅₀ of the particles of the mixed oxide B may preferably be from 1 to 10 μm, more preferably from 3 to 10 μm.

The present invention further provides a method of preparing mixed oxide B, wherein the mixed oxide A is heated to a temperature of 900 to 1100 ° C in 3 to 10 hours, then maintained at this temperature for 4 to 10 hours, and then cooled. It was subjected to a period of about 12 hours to room temperature. Preferably, dry air flows through the material throughout the period.

Thus, the preparation of mixed oxide B involves the method steps of preparing the mixed oxide A. In general, the preparation of mixed oxide B comprises a process in which a) atomizing a solution stream with a carrier gas to produce an aerosol, and the solution in each case comprises at least one metal compound from which the metal compound is derived a mixed oxide component consisting of lithium, nickel, cobalt and manganese having the desired stoichiometric ratio, b) transferring the aerosol to a reaction space where the aerosol is passed through a fuel gas and an oxygen-containing gas The reaction in the flame formed by the reaction, c) introducing the oxygen-containing gas into the flame at at least one additional location, and d) cooling the reaction stream and then separating the solid product from the reaction stream, e) the solid product is between 3 and 10 Heat to a temperature of 900 to 1100 ° C during the hour, then maintain at this temperature for a period of 4 to 10 hours and then cool to room temperature for a period of about 12 hours.

The present invention further provides a secondary battery comprising the mixture of the present invention The oxide is used as a positive electrode material.

Mixed oxide A

Solution used: With respect to Examples 1 to 8, a solution containing the salts specified in Table 1 was prepared in each case with water or an organic solvent. In Example 7, the solution additionally contained 1% by weight of carbon black Printex L (available from Evonik). In Example 8, the solution contained 1% by weight of 1,2,4,5-benzenetetracarboxylic acid. The amount is based on a solution that does not include carbon black or 1,2,4,5-benzenetetracarboxylic acid. An aerosol is prepared from the solution and nebulizer air using a nozzle and atomized into the reaction space. The aerosol is reacted in a hydrogen/air flame that is combusted there. Additional air is introduced into the flame at three locations. After cooling, the mixed oxide powder A is separated from the gaseous substance in the filter.

Mixed oxide B

The mixed oxide A is then heat treated in a rotary tube furnace for a specific period of time. The mixed oxides A from Examples 1 to 8 used produced the corresponding mixed oxides B of Examples 1 to 8. Example 9 is a mixed oxide of commercially available composition LiNi _1/3 Mn _1/3 Co _1/3 O ₂ . The air flow is dried using a compressed air adsorption dryer.

Table 1 provides all relevant parameters for the preparation of mixed oxide A and their physicochemical properties. Table 2 provides all relevant parameters for the preparation of mixed oxide B and their physicochemical properties.

The discharge capacity and irreversible loss were determined according to the prior art. For this purpose, a 2 cm ² electrode of a composite material consisting of mixed oxide B, carbon black (Ketjenblack) and PTFE from Examples 1 to 6 and 9 was used in each case as a weight ratio of 88:4:8. Half cell relative to metallic lithium and 1M LiPF6 electrolyte.

Claims (14)

a mixed oxide having a composition of Li _x Ni _a Co _b Mn _c O ₂ characterized by 0.8 x 1.2, 0.3 a 0.6, 0.1 b 0.4, c = 1 - ab, and a BET surface area of 5 to 30 m ² /g. According to the mixed oxide of the first aspect of the patent application, wherein 0.30 < a < 0.40 and 0.30 < b < 0.40. According to the mixed oxide of item 1 of the patent application, 0.35 of which a 0.45 and 0.15 b 0.30. Mixed oxide according to item 1 of the patent application, wherein 0.35<a 0.55 and 0.15 b 0.30. a mixed oxide according to any one of claims 1 to 4, wherein 0.98 x 1.07. The mixed oxide according to any one of claims 1 to 4, which has a carbon ratio of 0.1 to 2% by weight based on the carbon-containing mixed oxide. The mixed oxide according to any one of claims 1 to 4, wherein the mixed oxide has a d _{50 of} less than or equal to 10 μm. A method of preparing a mixed oxide according to any one of claims 1 to 7, characterized in that a) atomizing a solution with a carrier gas to produce an aerosol, and the solution comprises at least one in each case a metal compound derived from a mixed oxide component selected from the group consisting of lithium, nickel, cobalt, and manganese having a desired stoichiometric ratio, b) transferring the aerosol to a reaction space where the gas The sol is reacted in a flame formed by the reaction of a fuel gas and an oxygen-containing gas, c) introducing an oxygen-containing gas into the flame at at least one additional location, and d) cooling the reaction stream and then separating the solid product from the reaction stream . According to the method of claim 8, wherein the ratio λ of oxygen required to define the oxygen/combustion fuel gas is 1.05 to 2. The method of claim 8 or 9, wherein carbon black or graphite is introduced into the reaction space. The method of claim 8 or 9, wherein the aerosol has an average exit velocity of at least 50 ms ^-1 into the reaction space and an average velocity of the reaction mixture in the reaction space of from 0.1 ms ^-1 to 10 ms ^-1 . a mixed oxide having the composition Li _x Ni _a Co _b Mn _c O ₂ characterized by a) 0.8 x 1.2;0.3 a 0.6; 0.1 b 0.4; c = 1 - ab, b) having a BET surface area of from 2 m ² /g to less than 5 m ² /g, c) relative to the line of 2Θ=18.6±1° in the x-ray diffraction pattern The intensity ratio of the line of 2Θ=44.1±1° is at least 1.65. A method of preparing a mixed oxide according to claim 12 of the patent application, characterized in that the mixed oxide according to any one of claims 1 to 7 is heated to 900 to 1100 ° C in 3 to 10 hours. The temperature is then maintained at this temperature for a period of 4 to 10 hours and then cooled to room temperature for a period of about 12 hours. A secondary battery comprising the mixed oxide according to item 12 of the patent application as a positive electrode material.