A spray pyrolysis device and a method for preparing ternary positive electrode precursors by using the same

Abstract

The application discloses a spray pyrolysis device and a method for preparing ternary positive electrode precursors by using the same. The spray pyrolysis device comprises a feeding unit, a spraying unit and a pyrolysis unit; a first unit, a second unit and a third unit are sequentially arranged in a cavity of the spraying unit; an atomizing device is arranged at an outlet of the third unit; the first unit, the second unit and the third unit are heated by a first ultrasonic wave generating assembly, a second ultrasonic wave generating assembly and a third ultrasonic wave generating assembly respectively; the atomizing device is communicated with the pyrolysis unit, so that atomized liquid generated by the atomizing device enters the pyrolysis unit; a ignition device is arranged at an inlet of the pyrolysis unit; P1 < P2 < P3. The spray pyrolysis device can avoid the problems of particle breakage and hollowing of the positive electrode material precursor, so that the tap density of the positive electrode material precursor is high, the specific surface area is low, and the chlorine content is low, thereby improving the energy density, cycle performance and safety performance of the positive electrode material, and reducing the preparation cost.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a spray pyrolysis device and a method for preparing a ternary cathode precursor using the same. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic devices, power tools, energy storage devices, electric vehicles, and hybrid electric vehicles due to their advantages such as high operating potential, high specific energy, long cycle performance, and zero pollution. However, with the continuous expansion of lithium-ion battery usage, the prices of related raw materials are also rising, especially the prices of related scarce resources. The increase in raw material prices will inevitably lead to an increase in the cost of lithium-ion batteries, further negatively impacting their application.

[0003] Since cathode materials account for a significant portion of the overall battery cost, reducing the processing costs of cathode materials and their precursors is crucial for lowering the overall battery cost. Currently, ternary cathode precursors are typically synthesized using a co-precipitation method. This method is complex, time-consuming, and generates large amounts of ammonia nitrogen wastewater during production, requiring treatment and resulting in substantial environmental costs. In contrast, the spray pyrolysis method for preparing ternary cathode precursors is simpler and faster. The hydrogen chloride gas generated by this method can be absorbed, treated, and recycled, effectively reducing material processing costs.

[0004] The inventors discovered that when using acetate and nitrate as solutions to prepare lithium-ion cathode materials via spray pyrolysis, the low solubility of acetate in water and the low melting point of nitrate cause the outer edges of the atomized droplets to easily form a crust during the spray pyrolysis process. This results in the breakage or hollowing of secondary precursor particles. The ternary materials prepared from these precursors by high-temperature calcination exhibit low tap density and high specific surface area, which adversely affects the energy density, cycle performance, and safety performance of the battery. In addition, toxic and harmful gases are also generated.

[0005] Therefore, providing a strategy for preparing cathode material precursors by spray pyrolysis to avoid particle breakage and hollowing of cathode material precursors, resulting in high tap density, low specific surface area, and low chloride content of cathode material precursors, thereby improving the energy density, electrochemical performance, and safety performance of cathode materials and reducing preparation costs, is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, the present invention aims to provide a spray pyrolysis apparatus and a method for preparing ternary cathode precursors using the same.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a spray pyrolysis device, characterized in that the spray pyrolysis device includes a feeding unit, a spraying unit, and a pyrolysis unit;

[0009] The spray unit has a first unit, a second unit, and a third unit arranged sequentially inside its cavity. An atomizing device is provided at the outlet of the third unit. The first unit, the second unit, and the third unit are heated by a first ultrasonic generator component, a second ultrasonic generator component, and a third ultrasonic generator component, respectively. The atomizing device is connected to the pyrolysis unit so that the atomized liquid generated by the atomizing device enters the pyrolysis unit. An ignition device is provided at the inlet of the pyrolysis unit.

[0010] The output power of the ultrasonic generator in the first ultrasonic generating assembly is P1, the output power of the ultrasonic generator in the second ultrasonic generating assembly is P2, and the output power of the ultrasonic generator in the first ultrasonic generating assembly is P3. <P2<P3。

[0011] In the spray pyrolysis apparatus of this invention, by arranging a first unit, a second unit, and a third unit within the cavity of the spray unit, and utilizing ultrasound for heating, and by adjusting the output power of the ultrasonic generators in the first, second, and third units, ultrasonic gradient heating can be achieved. This ensures high heating efficiency and heating speed, accelerates the decomposition rate of salts in the salt solution, reduces the production cost of spray pyrolysis, and possesses certain economic advantages. Furthermore, using nickel chloride, cobalt chloride, and manganese chloride for the preparation of the cathode material precursor can avoid the problems of particle breakage and hollowing of the cathode material precursor, resulting in a high tap density, low specific surface area, and low chloride content in the cathode material precursor. This, in turn, improves the energy density, cycle performance, and safety performance of the cathode material, while reducing preparation costs.

[0012] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0013] Preferably, the first ultrasonic generating assembly includes at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity.

[0014] Preferably, in the first ultrasonic generating assembly, the ultrasonic generators are spaced at the same distance.

[0015] Preferably, the second ultrasonic generating assembly includes at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity.

[0016] Preferably, in the second ultrasonic generating assembly, the ultrasonic generators are spaced at the same distance.

[0017] Preferably, the third ultrasonic generating assembly includes at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity.

[0018] Preferably, in the third ultrasonic wave generating assembly, the ultrasonic wave generators are spaced at the same distance.

[0019] Preferably, the atomizing device is an ultrasonic oscillating atomizer.

[0020] Preferably, the feeding unit is used to store and supply salt solution to the spraying unit.

[0021] Preferably, the ignition device is an ignition burner.

[0022] Preferably, the spray pyrolysis device further includes a dechlorinator, the inlet of which is connected to the outlet of the pyrolysis unit.

[0023] Secondly, the present invention provides a method for preparing a ternary cathode precursor using the spray pyrolysis apparatus described in the first aspect, the method comprising the following steps:

[0024] (1) The chloride salt solution of the ternary cathode precursor is supplied to the spray unit through the feeding unit. The spray unit is heated by the ultrasonic action of the spray unit. The temperature of the first unit, the second unit and the third unit in the cavity of the spray unit increases sequentially to obtain the heated chloride salt solution.

[0025] (2) The heated chloride salt solution is atomized using an atomizing device to obtain an atomized liquid;

[0026] (3) Turn on the ignition device, ignite the atomizing liquid, and perform pyrolysis to obtain the ternary cathode precursor.

[0027] The method of this invention uses a chloride salt system and combines it with spray drying to prepare the ternary cathode material precursor. Because Cl... - It can be used as a nucleating agent, thus making it easier to form solid particles when using ultrasonic gradient heating, avoiding particle breakage and hollowing problems, improving the tap density of the cathode material precursor, and reducing its low specific surface area. Moreover, chloride salts have an advantage in raw material price compared to the other two types of salts (sulfates and nitrates), and the generated HCl gas can be recovered and reused, thus having certain secondary economic benefits.

[0028] Preferably, the chloride salt solution of the ternary cathode precursor includes lithium salt, nickel chloride, cobalt chloride and manganese chloride, wherein the molar ratio of lithium to the total molar ratio of nickel, cobalt and manganese is (1-1.1):1, for example, it can be 1:1, 1.02:1, 1.05:1, 1.07:1 or 1.1:1, etc.

[0029] Preferably, the lithium salt is at least one selected from lithium nitrate, lithium hydroxide, lithium nitrate and lithium chloride, and more preferably lithium chloride.

[0030] Preferably, the liquid inlet pressure of the atomizing device in the spray unit is 1 bar to 3 bar, for example, it can be 1 bar, 1.2 bar, 1.3 bar, 1.5 bar, 1.6 bar, 1.8 bar, 2 bar, 2.2 bar, 2.4 bar, 2.6 bar, 2.8 bar or 3 bar, etc.

[0031] Preferably, the liquid inlet velocity of the atomizing device in the spray unit is 0.1 m / s. 3 / h-3.0m 3 / h, for example, could be 0.1m 3 / h, 0.3m 3 / h, 0.5m 3 / h, 0.7m 3 / h, 1.0m 3 / h, 1.5m 3 / h, 1.8m 3 / h, 2.0m 3 / h, 2.2m 3 / h, 2.4m 3 / h, 2.6m 3 / h, 2.8m 3 / h or 3.0m 3 / h etc.

[0032] Preferably, the jet pressure of the atomizing device in the spray unit is 0.3MPa-0.8MPa, for example, it can be 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa or 0.8MPa, etc.

[0033] Preferably, the atomized liquid is introduced into the pyrolysis unit by a carrier gas, which includes at least one of dry compressed air, oxygen, or argon.

[0034] Preferably, the flow rate of the carrier gas is 40 m / s. 3 / h-200m 3 / h, for example, could be 40m 3 / h, 45m 3 / h, 50m 3 / h、55m 3 / h、60m 3 / h、65m 3 / h、70m 3 / h、75m 3 / h、80m 3 / h、85m3 / h、90m 3 / h、95m 3 / h、100m 3 / h、110m 3 / h、115m 3 / h, 120m 3 / h, 125m 3 / h, 130m 3 / h, 140m 3 / h, 145m 3 / h, 150m 3 / h, 160m 3 / h、165m 3 / h, 170m 3 / h、175m 3 / h, 180m 3 / h、190m 3 / h or 200m 3 / h etc.

[0035] Preferably, in the spray unit, the temperature in the first unit is 50℃-200℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃; the temperature in the second unit is 200℃-550℃, for example, it can be 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, 315℃, etc. 330℃, 350℃, 260℃, 380℃, 400℃, 420℃, 430℃, 450℃, 470℃, 480℃, 490℃, 500℃, 510℃, 530℃, or 550℃, etc.; the temperature in the third unit is 500℃-800℃, for example, it can be 500℃, 530℃, 560℃, 580℃, 600℃, 625℃, 650℃, 675℃, 700℃, 720℃, 740℃, 760℃, 780℃, or 800℃, etc.

[0036] Preferably, the output power P1 of the first unit is 2.0kW-2.5kW, for example, it can be 2.0kW, 2.1kW, 2.2kW, 2.3kW, 2.4kW or 2.5kW; the output power P2 of the second unit is 2.7kW-2.9kW, for example, it can be 2.7kW, 2.8kW or 2.9kW; and the output power of the third unit is 3.0kW-4.0kW, for example, it can be 3.2kW, 3.3kW, 3.4kW, 3.5kW, 3.6kW, 3.7kW, 3.8kW, 3.9kW or 4.0kW.

[0037] Preferably, the pyrolysis temperature is 750℃-1200℃, for example, it can be 750℃, 780℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃ or 1200℃, etc.

[0038] Preferably, the heating rate of the pyrolysis is 1℃ / min-10℃ / min, for example, it can be 1℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min or 10℃ / min, etc.

[0039] Preferably, the pyrolysis time is 5h-30h, for example, it can be 5h, 6h, 8h, 10h, 12h, 13h, 14h, 16h, 17h, 18h, 20h, 21h, 22h, 25h, 26h, 28h, 29h or 30h.

[0040] Preferably, the method further includes using a dechlorinator to remove chlorine from the pyrolysis products.

[0041] Preferably, the temperature inside the dechlorinator is 400℃-900℃, for example, it can be 400℃, 425℃, 450℃, 475℃, 500℃, 530℃, 560℃, 580℃, 600℃, 625℃, 650℃, 675℃, 700℃, 720℃, 740℃, 760℃, 780℃, 800℃, 850℃ or 900℃, etc.

[0042] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0043] Compared with existing technologies, the present invention has the following beneficial effects:

[0044] (1) The spray pyrolysis device and method of the present invention can avoid the problems of particle breakage and hollowing of the cathode material precursor, so that the cathode material precursor has high tap density, low specific surface area and low chloride content, thereby improving the energy density and cycle performance of the cathode material and reducing the preparation cost.

[0045] (2) The battery assembled with the cathode material of the present invention has good electrochemical performance, with an initial discharge capacity of more than 205.5 mAh / g and a capacity retention rate of more than 90.9% after 100 cycles. Attached Figure Description

[0046] Figure 1 This is a scanned image of the ternary 622 precursor of Embodiment 1 of the present invention. Detailed Implementation

[0047] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0048] The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0049] In one embodiment, the present invention provides a spray pyrolysis apparatus, the spray pyrolysis apparatus comprising a feeding unit, a spraying unit, and a pyrolysis unit;

[0050] The spray unit has a first unit, a second unit, and a third unit arranged sequentially inside its cavity. An atomizing device is provided at the outlet of the third unit. The first unit, the second unit, and the third unit are heated by a first ultrasonic generator component, a second ultrasonic generator component, and a third ultrasonic generator component, respectively. The atomizing device is connected to the pyrolysis unit so that the atomized liquid generated by the atomizing device enters the pyrolysis unit. An ignition device is provided at the inlet of the pyrolysis unit.

[0051] The output power of the ultrasonic generator in the first ultrasonic generating assembly is P1, the output power of the ultrasonic generator in the second ultrasonic generating assembly is P2, and the output power of the ultrasonic generator in the first ultrasonic generating assembly is P3. <P2<P3。

[0052] In one embodiment, the first ultrasonic generating assembly includes at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity.

[0053] In one embodiment, the ultrasonic generators in the first ultrasonic generating assembly are spaced at the same distance.

[0054] In one embodiment, the second ultrasonic generating assembly includes at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity.

[0055] In one embodiment, the ultrasonic generators in the second ultrasonic generating assembly are spaced at the same distance.

[0056] In one embodiment, the third ultrasonic generating assembly includes at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity.

[0057] In one embodiment, the ultrasonic generators in the third ultrasonic generating assembly are spaced at the same distance.

[0058] Preferably, the atomizing device is an ultrasonic oscillating atomizer.

[0059] In one embodiment, the feeding unit is used to store and supply salt solution to the spraying unit.

[0060] In one embodiment, the ignition device is an ignition burner.

[0061] In one embodiment, the spray pyrolysis apparatus further includes a dechlorinator, the inlet of which is connected to the outlet of the pyrolysis unit.

[0062] In one embodiment, the present invention provides a method for preparing a ternary cathode precursor using the above-described spray pyrolysis apparatus, the method comprising the following steps:

[0063] (1) The chloride salt solution of the ternary cathode precursor is supplied to the spray unit through the feeding unit. The spray unit is heated by the ultrasonic action of the spray unit. The temperature of the first unit, the second unit and the third unit in the cavity of the spray unit increases sequentially to obtain the heated chloride salt solution.

[0064] (2) The heated chloride salt solution is atomized using an atomizing device to obtain an atomized liquid;

[0065] (3) Turn on the ignition device, ignite the atomizing liquid, and perform pyrolysis to obtain the ternary cathode precursor.

[0066] In one embodiment, the chloride salt solution of the ternary cathode precursor includes lithium chloride, nickel chloride, cobalt chloride and manganese chloride, wherein the molar amount of lithium is in the ratio of the total molar amount of nickel, cobalt and manganese to (1-1.1):1.

[0067] In one embodiment, the lithium chloride is at least one of an organic acid salt of lithium or an inorganic acid salt of lithium, preferably lithium chloride.

[0068] In one embodiment, the inlet pressure of the atomizing device in the spray unit is 1 bar to 3 bar.

[0069] In one embodiment, the liquid inlet velocity of the atomizing device in the spray unit is 0.1 m / s. 3 / h-3.0m 3 / h.

[0070] In one embodiment, the jet pressure of the atomizing device in the spray unit is 0.3MPa-0.8MPa.

[0071] In one embodiment, the atomized liquid is introduced into the pyrolysis unit via a carrier gas, the carrier gas including at least one of dry compressed air, oxygen, or argon.

[0072] In one embodiment, the carrier gas flow rate is 40 m / s. 3 / h-200m 3 / h.

[0073] In one embodiment, the temperature in the first unit of the spray unit is 50℃-200℃, the temperature in the second unit is 200℃-550℃, and the temperature in the third unit is 500℃-800℃.

[0074] In one embodiment, the pyrolysis temperature is 750°C-1200°C.

[0075] In one embodiment, the heating rate of the pyrolysis is 1°C / min to 10°C / min.

[0076] In one embodiment, the pyrolysis time is 5h-30h.

[0077] In one embodiment, the method further includes using a dechlorinator to remove chlorine from the pyrolysis products.

[0078] In one embodiment, the temperature inside the dechlorinator is 400°C-900°C.

[0079] In one embodiment, the present invention also provides a method for preparing ternary cathode materials using the above-described ternary cathode precursor, comprising the following steps:

[0080] In a pure oxygen atmosphere, the ternary cathode precursor is sintered in a tube furnace. The temperature is first increased from room temperature to 400℃-600℃ (e.g., 400℃, 425℃, 450℃, 470℃, 500℃, 525℃, 550℃, 560℃, 580℃, or 600℃) at a rate of 1℃ / min-10℃ / min (e.g., 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min, etc.), and held at this temperature for 2h-5h (e.g., 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h, etc.), and then increased at a rate of 1℃ / min... The temperature is increased to 750℃-1000℃ (e.g., 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min) at a heating rate of n-10℃ / min (e.g., 750℃, 775℃, 800℃, 830℃, 860℃, 880℃, 900℃, 950℃, or 1000℃) and held for 6h-12h (e.g., 6h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h, or 12h). The temperature is then allowed to cool naturally to room temperature. The material is then removed, ground, and sieved to obtain the ternary cathode material.

[0081] In this embodiment of the invention, a ternary cathode precursor, specifically ternary 622, is used as an example to illustrate the preparation method. However, the method of the present invention is not limited to ternary 622 precursors; the preparation of other ternary precursors is also applicable to the present invention. The chemical formula of the ternary 622 precursor is Ni. 0.6 Co 0.2 Mn 0.2 (OH)2.

[0082] Example 1

[0083] This embodiment provides a method for preparing a ternary 622 precursor, which is carried out in the spray pyrolysis apparatus provided in the above embodiment, and includes the following steps:

[0084] (1) Preparation of ternary 622 precursor mixed solution

[0085] With a molar ratio of Li:(Ni+Co+Mn)=1.04:1 and Ni:Co:Mn=0.6:0.2:0.2, accurately weigh a certain mass of LiCl, NiCl2·6H2O, CoCl2·6H2O and MnCl2·4H2O, dissolve them in deionized water to prepare a mixed solution with a total metal ion concentration of 2.5mol / L.

[0086] (2) Preparation of ternary 622 precursor

[0087] The mixed solution is atomized by an atomizing device, which is an ultrasonic oscillating atomizer. Then, an ignition device is used to ignite the atomized liquid to burn, thereby causing the mixed solution to undergo thermal decomposition. The chlorine in the pyrolysis products is removed by a dechlorinator. The resulting powder is ground through a 300-mesh sieve to obtain the ternary 622 precursor, which is recorded as 1-a.

[0088] The control operating parameters are as follows: liquid inlet pressure of the atomizing device is 1.2 bar, and liquid inlet velocity is 0.7 m / s. 3 The carrier gas is dry compressed air, with a jet pressure of 0.35 MPa and a flow rate of 80 m / h. 3 / h; The temperature in the first unit is set at 200℃, and the output power P1 of the first unit is 2.4kW; the temperature in the second unit is set at 400℃, and the output power P2 of the second unit is 2.8kW; the temperature in the third unit is set at 800℃, and the output power of the third unit is 3.2kW; the pyrolysis unit uses electric heating, the temperature in the pyrolysis unit is set at 850℃, the pyrolysis heating rate is 5℃ / min, and the pyrolysis time is 15h; the dechlorinator uses electric heating, and the temperature in the dechlorinator is set at 800℃.

[0089] Figure 1This is a scan image of the ternary 622 precursor (i.e., sample 1-a) in this embodiment. As can be seen from the image, the particles have a regular, near-spherical morphology, with a maximum particle size of approximately 10 μm and a minimum of approximately 3 μm. No broken or hollow secondary particles were observed. This indicates that under the process conditions of this invention, microwave gradient heating combined with the use of nickel-cobalt-manganese chloride salts does indeed contribute to the formation of solid secondary particle precursors.

[0090] This embodiment also provides a method for preparing ternary 622 cathode material using the above-mentioned ternary 622 precursor, including the following steps:

[0091] Under a pure oxygen atmosphere, the ternary 622 precursor prepared in step (2) is sintered in a tube furnace. The temperature is first raised from room temperature to 500°C at 3°C / min, and held at this temperature for 3 hours. Then, the temperature is raised to 880°C at the same rate and held for 10 hours. The temperature is then naturally cooled to room temperature. The material is taken out and ground through a 300-mesh sieve to obtain the ternary 622 cathode material, which is recorded as 1-b.

[0092] Example 2

[0093] This embodiment provides a method for preparing a ternary 622 precursor, which is carried out in the spray pyrolysis apparatus provided in the above embodiment, and includes the following steps:

[0094] (1) Preparation of ternary 622 precursor mixed solution

[0095] With a molar ratio of Li:(Ni+Co+Mn)=1.1:1 and Ni:Co:Mn=0.6:0.2:0.2, accurately weigh a certain mass of LiCl, NiCl2·6H2O, CoCl2·6H2O and MnCl2·4H2O, dissolve them in deionized water to prepare a mixed solution with a total metal ion concentration of 2.0 mol / L.

[0096] (2) Preparation of ternary 622 precursor

[0097] The mixed solution is atomized by an atomizing device, which is an ultrasonic oscillating atomizer. Then, an ignition device is used to ignite the atomized liquid to burn, thereby causing the mixed solution to undergo thermal decomposition. The chlorine in the pyrolysis products is removed by a dechlorinator. The resulting powder is ground through a 300-mesh sieve to obtain the ternary 622 precursor, which is recorded as 2-a.

[0098] The control operating parameters are as follows: liquid inlet pressure of the atomizing device is 2.0 bar, and liquid inlet velocity is 2.0 m / s. 3 The carrier gas is dry compressed air, with a jet pressure of 0.5 MPa and a flow rate of 120 m / h. 3 / h; The temperature in the first unit is set at 150℃, and the output power P1 of the first unit is 2.0kW; the temperature in the second unit is set at 300℃, and the output power P2 of the second unit is 2.7kW; the temperature in the third unit is set at 700℃, and the output power P3 of the third unit is 3.1kW; the pyrolysis unit uses electric heating, the temperature in the pyrolysis unit is set at 1000℃, the pyrolysis heating rate is 10℃ / min, and the pyrolysis time is 8h; the dechlorinator uses electric heating, and the temperature in the dechlorinator is set at 600℃.

[0099] This embodiment also provides a method for preparing ternary 622 cathode material using the above-mentioned ternary 622 precursor, including the following steps:

[0100] Under a pure oxygen atmosphere, the ternary 622 precursor prepared in step (2) is sintered in a tube furnace. The temperature is first raised from room temperature to 600℃ at 5℃ / min, and held at this temperature for 2 hours. Then, the temperature is raised to 950℃ at the same rate and held for 8 hours. The temperature is then naturally cooled to room temperature. The material is taken out and ground through a 300-mesh sieve to obtain the ternary 622 cathode material, which is recorded as 2-b.

[0101] Example 3

[0102] This embodiment provides a method for preparing a ternary 622 precursor, which is carried out in the spray pyrolysis apparatus provided in the above embodiment, and includes the following steps:

[0103] (1) Preparation of ternary 622 precursor mixed solution

[0104] With a molar ratio of Li:(Ni+Co+Mn)=1.01:1 and Ni:Co:Mn=0.6:0.2:0.2, accurately weigh a certain mass of LiCl, NiCl2·6H2O, CoCl2·6H2O and MnCl2·4H2O, dissolve them in deionized water to prepare a mixed solution with a total metal ion concentration of 2.7mol / L.

[0105] (2) Preparation of ternary 622 precursor

[0106] The mixed solution is atomized by an atomizing device, which is an ultrasonic oscillating atomizer. Then, an ignition device is used to ignite the atomized liquid to burn, thereby causing thermal decomposition of the mixed solution. The chlorine in the pyrolysis products is removed by a dechlorinator. The resulting powder is ground through a 300-mesh sieve to obtain the ternary 622 precursor, which is recorded as 3-a.

[0107] The control operating parameters are as follows: liquid inlet pressure of the atomizing device is 3.0 bar, and liquid inlet velocity is 2.5 m / s. 3 The carrier gas is dry argon, with a jet pressure of 0.75 MPa and a flow rate of 200 m / h.3 / h; The temperature in the first unit is set at 100℃, and the output power P1 of the first unit is 2.2kW; the temperature in the second unit is set at 500℃, and the output power P2 of the second unit is 2.9kW; the temperature in the third unit is set at 650℃, and the output power P3 of the third unit is 3.0kW; the pyrolysis unit uses electric heating, the temperature in the pyrolysis unit is set at 1100℃, the pyrolysis heating rate is 10℃ / min, and the pyrolysis time is 5h; the dechlorinator uses electric heating, and the temperature in the dechlorinator is set at 750℃.

[0108] This embodiment also provides a method for preparing ternary 622 cathode material using the above-mentioned ternary 622 precursor, including the following steps:

[0109] Under a pure oxygen atmosphere, the ternary 622 precursor prepared in step (2) is sintered in a tube furnace. The temperature is first raised from room temperature to 500°C at 4°C / min, and held at this temperature for 4 hours. Then, the temperature is raised to 920°C at the same rate and held for 7 hours. The temperature is then allowed to cool naturally to room temperature. The material is then removed and ground through a 300-mesh sieve to obtain the ternary 622 cathode material, which is recorded as 3-b.

[0110] Comparative Example 1

[0111] The difference between this comparative example and Example 1 is that the heating method for the first, second, and third units was changed from ultrasonic heating to electric heating. The resulting precursor sample is recorded as 1-A, and the cathode material is recorded as 1-B.

[0112] Comparative Example 2

[0113] The difference between this comparative example and Example 1 is that LiCl, NiCl2·6H2O, CoCl2·6H2O, and MnCl2·4H2O were all replaced with nitrates. The resulting precursor sample is recorded as 2-A, and the cathode material is recorded as 2-B.

[0114] The average particle size, tap density, specific surface area, and chloride content of the precursors of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0115] Table 1. Physicochemical parameters of the precursor samples prepared in the embodiments and comparative examples of the present invention.

[0116]

[0117] The battery was assembled and its electrochemical performance was tested. The battery assembly method was as follows: 75 wt% of positive electrode material (Examples 1-3 and Comparative Examples 1-2), 10 wt% of Super-P and 15 wt% of polyvinylidene fluoride (PVDF) were dispersed in N-methylpyrrolidone (NMP) solution to prepare positive electrode slurry, which was then coated on aluminum foil and dried to obtain the positive electrode.

[0118] Lithium foil serves as the negative electrode;

[0119] The diaphragm is a PP microporous membrane (Celgard2400);

[0120] The electrolyte composition is: 1M LiPF6 (the solvent is a mixture of EC, DMC and EMC, wherein the volume ratio of EC:DMC:EMC is 1:1:1);

[0121] The above-mentioned positive electrode, separator, negative electrode and electrolyte are assembled to obtain a coin cell.

[0122] Performance testing: The electrochemical performance of the cathode material was tested at room temperature and a rate of 0.1C. The results are shown in Table 2.

[0123] Table 2 Electrochemical performance of the cathode materials prepared in the embodiments and comparative examples of the present invention.

[0124]

[0125]

[0126] As shown in Tables 1 and 2, the spray pyrolysis device and method of the present invention can avoid the problems of particle breakage and hollowing of the cathode material precursor, resulting in high tap density, low specific surface area and low chloride content of the cathode material precursor, thereby improving the energy density, cycle performance and safety performance of the cathode material and reducing the preparation cost.

[0127] Comparative Example 1 had a high residual chlorine content in the precursor due to the replacement of microwave heating with electric heating, which needs to be addressed through post-processing.

[0128] In Comparative Example 2, nitrates were used instead of chlorides. Nitrates have high pyrolysis temperatures and poor thermal stability at high temperatures. Oxygen is also produced during pyrolysis, resulting in poor physicochemical properties of the precursors produced using nitrates as raw materials. Consequently, the electrochemical performance of the resulting cathode material is also not optimistic.

[0129] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a ternary cathode precursor using a spray pyrolysis device, characterized in that, The method includes the following steps: (1) The chloride salt solution of the ternary cathode precursor is supplied to the spray unit through the feeding unit. The spray unit is heated by the ultrasonic action of the spray unit. The temperature of the first unit, the second unit and the third unit in the cavity of the spray unit increases sequentially to obtain the heated chloride salt solution. (2) The heated chloride salt solution is atomized using an atomizing device to obtain an atomized liquid; (3) Turn on the ignition device, ignite the atomizing liquid, and perform pyrolysis to obtain a ternary cathode precursor; The battery assembled from the ternary cathode precursor material prepared by the method has an initial discharge capacity ≥205.5mAh / g; The spray pyrolysis device includes a feeding unit, a spraying unit, and a pyrolysis unit; The spray unit has a first unit, a second unit, and a third unit arranged sequentially inside its cavity. An atomizing device is installed at the outlet of the third unit. The first, second, and third units are heated by a first ultrasonic generator assembly, a second ultrasonic generator assembly, and a third ultrasonic generator assembly, respectively. The atomizing device is connected to the pyrolysis unit, allowing the atomized liquid generated by the atomizing device to enter the pyrolysis unit. An ignition device, specifically an ignition burner, is installed at the inlet of the pyrolysis unit. The atomizing device is an ultrasonic oscillating atomizer; The output power of the ultrasonic generator in the first ultrasonic generator assembly is P1, the output power of the ultrasonic generator in the second ultrasonic generator assembly is P2, and the output power of the ultrasonic generator in the first ultrasonic generator assembly is P3, where P1 < P2 < P3.

2. The method according to claim 1, characterized in that, The first ultrasonic generating assembly includes at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity.

3. The method according to claim 1, characterized in that, In the first ultrasonic generating assembly, the ultrasonic generators are spaced at the same distance.

4. The method according to claim 1, characterized in that, The second ultrasonic generating assembly includes at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity.

5. The method according to claim 1, characterized in that, In the second ultrasonic generating assembly, the ultrasonic generators are spaced at the same distance.

6. The method according to claim 1, characterized in that, The third ultrasonic generating component includes at least two ultrasonic generators symmetrically arranged along the circumference of the cavity.

7. The method according to claim 1, characterized in that, In the third ultrasonic wave generating assembly, the ultrasonic wave generators are spaced at the same distance.

8. The method according to claim 1, characterized in that, The feeding unit is used to store and supply salt solution to the spraying unit.

9. The method according to claim 1, characterized in that, The spray pyrolysis device also includes a dechlorinator, the inlet of which is connected to the outlet of the pyrolysis unit.

10. The method according to claim 1, characterized in that, The chloride salt solution of the ternary cathode precursor includes lithium salt, nickel chloride, cobalt chloride and manganese chloride, wherein the molar ratio of lithium to the total molar ratio of nickel, cobalt and manganese is (1-1.1):

1.

11. The method according to claim 10, characterized in that, The lithium salt is at least one of lithium nitrate, lithium hydroxide, lithium nitrate, and lithium chloride.

12. The method according to claim 11, characterized in that, The lithium salt is lithium chloride.

13. The method according to claim 1, characterized in that, The liquid inlet pressure of the atomizing device in the spray unit is 1 bar to 3 bar.

14. The method according to claim 1, characterized in that, The liquid inlet velocity of the atomizing device in the spray unit is 0.1 m³ / h-3.0 m³ / h.

15. The method according to claim 1, characterized in that, The jet pressure of the atomizing device in the spray unit is 0.3MPa-0.8MPa.

16. The method according to claim 1, characterized in that, The atomized liquid is introduced into the pyrolysis unit by a carrier gas, which includes at least one of dry compressed air, oxygen, or argon.

17. The method according to claim 16, characterized in that, The flow rate of the carrier gas is 40 m³ / h-200 m³ / h.

18. The method according to claim 1, characterized in that, In the spray unit, the temperature in the first unit is 50℃-200℃, the temperature in the second unit is 200℃-550℃, and the temperature in the third unit is 500℃-800℃.

19. The method according to claim 1, characterized in that, The first unit has an output power P1 of 2.0kW-2.5kW, the second unit has an output power P2 of 2.7kW-2.9kW, and the third unit has an output power of 3.0kW-4.0kW.

20. The method according to claim 1, characterized in that, The pyrolysis temperature is 750℃-1200℃.

21. The method according to claim 1, characterized in that, The heating rate of the pyrolysis is 1℃ / min-10℃ / min.

22. The method according to claim 1, characterized in that, The pyrolysis time is 5h-30h.

23. The method according to claim 1, characterized in that, The method also includes using a dechlorinator to remove chlorine from the pyrolysis products.

24. The method according to claim 23, characterized in that, The temperature inside the dechlorinator is 400℃-900℃.

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