Spray pyrolysis device and method for preparing ternary positive electrode precursor by using same

Abstract

The invention discloses a spray pyrolysis device and a method for preparing a ternary positive electrode precursor by adopting the spray pyrolysis device. The spray pyrolysis device comprises a feeding unit, a spray 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, and the first unit, the second unit and the third unit are heated through a first ultrasonic generating assembly, a second ultrasonic generating assembly and a third ultrasonic generating assembly respectively. The atomization device is communicated with the pyrolysis unit, so that atomized liquid generated by the atomization device enters the pyrolysis unit, and an ignition device is arranged at an inlet of the pyrolysis unit; p1lt; p2lt; P2lt; and P3. The spray pyrolysis device disclosed by the invention can avoid the problems of particle crushing and hollowing of the positive electrode material precursor, so that the positive electrode material precursor is high in tap density, low in specific surface area and low in chlorine content, further the energy density, the cycle performance and the safety performance of the positive electrode material are improved, and the preparation cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries and relates to a spray pyrolysis device and a method for preparing a ternary positive electrode precursor by using the same. Background Art

[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 high working potential, high specific energy, long cycle performance and pollution-free. However, with the continuous expansion of the scale of lithium-ion battery use, the price of related raw materials is also getting higher and higher, especially the price of related scarce resources. The rise in raw material prices will inevitably lead to an increase in the cost of lithium-ion batteries, which will further have an adverse impact on the application of lithium-ion batteries.

[0003] Since the cathode material accounts for a relatively high proportion of the entire battery cost, reducing the processing cost of the cathode material and the cathode material precursor is a key means to reduce the overall battery cost. At present, the ternary cathode precursor is usually synthesized by the coprecipitation method, which is complex and time-consuming, and generates a large amount of ammonia nitrogen wastewater during the production process, which needs to be treated, resulting in considerable environmental costs. In contrast, the process of preparing the ternary cathode precursor by spray pyrolysis is simpler and takes less time. The hydrogen chloride gas generated by this method can be recycled and reused after absorption treatment, thereby effectively reducing the processing cost of the material.

[0004] The inventors found that when acetate and nitrate are used as solutions to prepare lithium-ion positive electrode materials by spray pyrolysis, due to the low solubility of acetate in water and the low melting point of nitrate, the outer edges of the atomized droplets of these two solutions are prone to crusting during the spray pyrolysis process, causing the secondary precursor particles to break or become hollow. As a result, the ternary material prepared by high-temperature calcination of this precursor has a low tap density and a high specific surface area, which has an adverse effect on the energy density, cycle performance and safety performance of the battery, and also produces toxic and harmful gases.

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

[0006] In view of the above problems existing in the prior art, the object of the present invention is to provide a spray pyrolysis device and a method for preparing a ternary positive electrode precursor using the same.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

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

[0009] The cavity of the spray unit is provided with a first unit, a second unit and a third unit in sequence, 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 the first ultrasonic generating component, the second ultrasonic generating component and the third ultrasonic generating component respectively, the atomizing device is connected with the pyrolysis unit so that the atomized liquid generated by the atomizing device enters the pyrolysis unit, and 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 component is P1, the output power of the ultrasonic generator in the second ultrasonic generating component is P2, the output power of the ultrasonic generator in the first ultrasonic generating component is P3, and P1 <P2<P3。

[0011] In the spray pyrolysis device of the present invention, by arranging the first unit, the second unit and the third unit in the cavity of the spray unit, using ultrasound for heating, and regulating the output power of the ultrasonic generator in the first unit, the second unit and the third unit, ultrasonic gradient heating can be achieved, which can ensure high heating efficiency and heating speed, accelerate the decomposition rate of salts in the salt solution, reduce the production cost of spray pyrolysis, and have certain economic advantages. Moreover, the use of nickel chloride, cobalt chloride and manganese chloride to prepare the positive electrode material precursor can avoid the particle crushing and hollowing problems of the positive electrode material precursor, so that the positive electrode material precursor has a high tap density, a low specific surface area, and a low chloride content, thereby improving the energy density, cycle performance and safety performance of the positive electrode material, and reducing the preparation cost.

[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. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[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 spacings between ultrasonic generators are the same.

[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 spacings between the ultrasonic generators are the same.

[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 generating assembly, the spacings between ultrasonic generators are the same.

[0019] Preferably, the atomization device is an ultrasonic oscillation atomizer.

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

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

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

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

[0024] (1) supplying a chloride salt solution of a ternary positive electrode precursor to a spray unit through a feeding unit, heating the solution through ultrasonic action of the spray unit, and increasing the temperatures of a first unit, a second unit, and a third unit in a cavity of the spray unit in sequence to obtain a heated chloride salt solution;

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

[0026] (3) Turn on the ignition device, ignite the atomized liquid, and perform thermal decomposition to obtain a ternary cathode precursor.

[0027] The method of the present invention uses a chloride salt system and cooperates with a spray drying method to prepare a ternary cathode material precursor. - It can be used as a nucleating agent, so when using ultrasonic gradient heating, it is easier to form solid particles, avoid particle breakage and hollowing problems, increase the tap density of the cathode material precursor, and reduce its specific surface area. Moreover, chloride salts have an advantage in raw material prices compared to the other two types of salts (sulfates and nitrates), and the generated HCl gas can be recycled and reused, so it has certain secondary economic benefits.

[0028] Preferably, the chloride salt solution of the ternary positive electrode precursor includes lithium salt, nickel chloride, cobalt chloride and manganese chloride, wherein the ratio of the molar amount of lithium element to the total molar amount of the nickel element, cobalt element and manganese element 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 of lithium nitrate, lithium hydroxide, lithium nitrate and lithium chloride, preferably lithium chloride.

[0030] Preferably, the liquid inlet pressure of the atomizing device in the spray unit is 1 bar-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 speed of the atomizing device in the spray unit is 0.1 m / s. 3 / h-3.0m 3 / h, for example, it can 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 0.3 MPa-0.8 MPa, for example, it can be 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa or 0.8 MPa.

[0033] Preferably, the atomized liquid is brought into the pyrolysis unit by a carrier gas, and the carrier gas 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, 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°C-200°C, for example, it can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C; the temperature in the second unit is 200°C-550°C, for example, it can be 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 315°C, ℃, 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, etc.; 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, etc.; 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, etc.

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

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

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

[0040] Preferably, the method further comprises removing chlorine from the pyrolysis product using a dechlorinator.

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

[0042] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

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

[0045] (2) The battery assembled with the positive electrode 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a scan image of the ternary 622 precursor of Example 1 of the present invention. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0048] The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] In one embodiment, the present invention provides a spray pyrolysis device, which includes a feeding unit, a spray unit and a pyrolysis unit;

[0050] The cavity of the spray unit is provided with a first unit, a second unit and a third unit in sequence, 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 the first ultrasonic generating component, the second ultrasonic generating component and the third ultrasonic generating component respectively, the atomizing device is connected with the pyrolysis unit so that the atomized liquid generated by the atomizing device enters the pyrolysis unit, and 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 component is P1, the output power of the ultrasonic generator in the second ultrasonic generating component is P2, the output power of the ultrasonic generator in the first ultrasonic generating component is P3, and P1 <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, in the first ultrasonic wave generating assembly, the intervals between the ultrasonic wave generators are the same.

[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, in the second ultrasonic wave generating assembly, the intervals between the ultrasonic wave generators are the same.

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

[0057] In one embodiment, in the third ultrasonic wave generating assembly, the spacings between the ultrasonic wave generators are the same.

[0058] Preferably, the atomization device is an ultrasonic oscillation atomizer.

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

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

[0061] In one embodiment, the spray pyrolysis device further comprises a dechlorinator, and an inlet of the dechlorinator is connected to an outlet of the pyrolysis unit.

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

[0063] (1) supplying a chloride salt solution of a ternary positive electrode precursor to a spray unit through a feeding unit, heating the solution through ultrasonic action of the spray unit, and increasing the temperatures of a first unit, a second unit, and a third unit in a cavity of the spray unit in sequence to obtain a heated chloride salt solution;

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

[0065] (3) Turn on the ignition device, ignite the atomized liquid, and perform thermal decomposition to obtain a ternary cathode precursor.

[0066] In one embodiment, the chloride salt solution of the ternary positive electrode precursor includes lithium chloride, nickel chloride, cobalt chloride and manganese chloride, wherein the ratio of the molar amount of lithium element to the total molar amount of the nickel element, cobalt element and manganese element is (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 liquid inlet pressure of the atomizing device in the spray unit is 1 bar-3 bar.

[0069] In one embodiment, the liquid inlet speed 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 0.3 MPa-0.8 MPa.

[0071] In one embodiment, the atomized liquid is brought into the pyrolysis unit by a carrier gas, and the carrier gas includes at least one of dry compressed air, oxygen or argon.

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

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

[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-10°C / min.

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

[0077] In one embodiment, the method further comprises removing chlorine from the pyrolysis product using a dechlorinator.

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

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

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

[0081] In the embodiment of the present invention, the preparation method is exemplified by taking the ternary positive electrode precursor as the ternary 622 precursor, but the method of the present invention is not limited to the ternary 622 precursor, and 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 device provided in the above embodiment, and comprises the following steps:

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

[0085] A certain mass of LiCl, NiCl2·6H2O, CoC12·6H2O and MnC12·4H2O were accurately weighed at a molar ratio of Li:(Ni+Co+Mn)=1.04:1, Ni:Co:Mn=0.6:0.2:0.2, and deionized water was added to dissolve them into a mixed solution with a total metal ion concentration of 2.5 mol / L.

[0086] (2) Preparation of ternary 622 precursor

[0087] The mixed solution is atomized by an atomizing device, which is an ultrasonic oscillation atomizer, and then an ignition device is used to ignite the atomized liquid to burn, so that the mixed solution undergoes thermal decomposition, and the chlorine in the thermal decomposition product is removed by a dechlorinator. The obtained powder is ground through a 300-mesh sieve to obtain a ternary 622 precursor, which is recorded as 1-a;

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

[0089] Figure 1This is a scan of the ternary 622 precursor (i.e., sample 1-a) of this embodiment. As can be seen from the figure, the morphology of the particles is regular spherical, with a maximum particle size of about 10 μm and a minimum particle size of about 3 μm. No broken or hollow secondary particles are seen. This shows that under the process conditions of the present invention, microwave gradient heating combined with the use of nickel, cobalt, manganese, and chloride salts does help to form a solid secondary particle precursor.

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

[0091] In a pure oxygen atmosphere, the ternary 622 precursor prepared in step (2) was sintered in a tubular furnace, firstly raised from room temperature to 500°C at a rate of 3°C / min, maintained at this temperature for 3 hours, then raised to 880°C at the same rate and maintained for 10 hours, cooled naturally to room temperature, and the material was taken out and ground through a 300-mesh sieve to obtain the ternary 622 positive electrode material, 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 device provided in the above embodiment, and the method comprises the following steps:

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

[0095] Accurately weigh a certain mass of LiCl, NiCl2·6H2O, CoC12·6H2O and MnC12·4H2O in a molar ratio of Li:(Ni+Co+Mn)=1.1:1, Ni:Co:Mn=0.6:0.2:0.2, add deionized water to dissolve and 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 oscillation atomizer, and then an ignition device is used to ignite the atomized liquid to burn, so that the mixed solution undergoes thermal decomposition, and the chlorine in the thermal decomposition product is removed by a dechlorinator. The obtained powder is ground through a 300-mesh sieve to obtain a ternary 622 precursor, which is recorded as 2-a;

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

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

[0100] Under a pure oxygen atmosphere, the ternary 622 precursor prepared in step (2) was sintered in a tubular furnace, first raised from room temperature to 600°C at a rate of 5°C / min, maintained at this temperature for 2 h, then raised to 950°C at the same rate and maintained for 8 h, naturally cooled to room temperature, and the material was taken out and ground through a 300-mesh sieve to obtain the ternary 622 positive electrode material, 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 device provided in the above embodiment, and the method comprises the following steps:

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

[0104] Accurately weigh a certain mass of LiCl, NiCl2·6H2O, CoC12·6H2O and MnC12·4H2O in a molar ratio of Li:(Ni+Co+Mn)=1.01:1, Ni:Co:Mn=0.6:0.2:0.2, add deionized water to dissolve and prepare a mixed solution with a total metal ion concentration of 2.7 mol / L.

[0105] (2) Preparation of ternary 622 precursor

[0106] The mixed solution is atomized by an atomizing device, which is an ultrasonic oscillation atomizer, and then an ignition device is used to ignite the atomized liquid to burn, so that the mixed solution undergoes thermal decomposition, and the chlorine in the thermal decomposition product is removed by a dechlorinator. The obtained powder is ground through a 300-mesh sieve to obtain a ternary 622 precursor, which is recorded as 3-a;

[0107] The control operation parameters are as follows: the liquid inlet pressure of the atomizer is 3.0 bar, the liquid inlet speed is 2.5 m 3 / h, the carrier gas is dry argon, the jet pressure is 0.75MPa, and the flow rate of the carrier gas is 200m3 / h; the temperature in the first unit is set at 100°C, the output power P1 of the first unit is 2.2kW, the temperature in the second unit is set at 500°C, the output power P2 of the second unit is 2.9kW, the temperature in the third unit is set at 650°C, the output power P3 of the third unit is 3.0kW; the pyrolysis unit adopts electric heating, the temperature in the pyrolysis unit is set to 1100°C, the heating rate of pyrolysis is 10°C / min, and the pyrolysis time is 5h; the dechlorinator adopts electric heating, and the temperature in the dechlorinator is set to 750°C.

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

[0109] Under pure oxygen atmosphere, the ternary 622 precursor prepared in step (2) was sintered in a tubular furnace, firstly raised from room temperature to 500°C at a rate of 4°C / min, maintained at this temperature for 4 hours, then raised to 920°C at the same rate and maintained for 7 hours, and naturally cooled to room temperature. The material was taken out and ground through a 300-mesh sieve to obtain the ternary 622 positive electrode material, which was recorded as 3-b.

[0110] Comparative Example 1

[0111] The difference between this comparative example and Example 1 is that the heating method of the first unit, the second unit and the third unit is replaced by electric heating instead of ultrasonic heating. The obtained precursor sample is recorded as 1-A, and the positive electrode 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, CoC12·6H2O and MnC12·4H2O are all replaced by nitrates. The obtained precursor sample is recorded as 2-A, and the positive electrode 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 Physical and chemical parameters of the precursor samples prepared in the examples of the present invention and the comparative examples

[0116]

[0117] Assembling a battery and testing the electrochemical performance, the method of assembling the battery is: dispersing 75wt% of the positive electrode material (Examples 1-3 and Comparative Examples 1-2), 10wt% of Super-P and 15wt% of polyvinylidene fluoride (PVDF) in an N-methylpyrrolidone (NMP) solution to prepare a positive electrode slurry, coating it on an aluminum foil, and drying to obtain a positive electrode;

[0118] The lithium sheet is the negative electrode;

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

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

[0121] The positive electrode, separator, negative electrode and electrolyte are assembled to obtain a button battery.

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

[0123] Table 2 Electrochemical properties of the positive electrode materials prepared in the examples of the present invention and the comparative examples

[0124]

[0125]

[0126] It can be seen from Table 1 and Table 2 that the spray pyrolysis device and method of the present invention can avoid the particle breakage and hollowing problems of the positive electrode material precursor, so that the positive electrode material precursor has a high tap density, a low specific surface area, and a low chloride content, thereby improving the energy density, cycle performance and safety performance of the positive electrode material and reducing the preparation cost.

[0127] In Comparative Example 1, since electric heating is used instead of microwave heating, the residual chlorine content in the precursor is high, which needs to be solved through post-treatment.

[0128] In Comparative Example 2, nitrate is used to replace chloride. Nitrate has a high pyrolysis temperature and poor thermal stability at high temperature. Oxygen is also produced during the pyrolysis process, resulting in poor physical and chemical indicators of the precursor produced using nitrate as a raw material, and the electrochemical performance of the obtained positive electrode material is not optimistic.

[0129] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various 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 spray pyrolysis device, characterized in that: The spray pyrolysis device comprises a feeding unit, a spray unit and a pyrolysis unit; The cavity of the spray unit is provided with a first unit, a second unit and a third unit in sequence, 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 the first ultrasonic generating component, the second ultrasonic generating component and the third ultrasonic generating component respectively, the atomizing device is connected with the pyrolysis unit so that the atomized liquid generated by the atomizing device enters the pyrolysis unit, and an ignition device is provided at the inlet of the pyrolysis unit; The output power of the ultrasonic generator in the first ultrasonic generating component is P1, the output power of the ultrasonic generator in the second ultrasonic generating component is P2, the output power of the ultrasonic generator in the first ultrasonic generating component is P3, and P1 <P2<P3。 2. The spray pyrolysis device according to claim 1, characterized in that: The first ultrasonic generating assembly comprises at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity; Preferably, in the first ultrasonic generating assembly, the spacings between the ultrasonic generators are the same; Preferably, the second ultrasonic generating assembly comprises at least two ultrasonic generators symmetrically arranged along the circumferential direction of the cavity; Preferably, in the second ultrasonic generating assembly, the spacings between the ultrasonic generators are the same; Preferably, the third ultrasonic wave generating assembly comprises at least two ultrasonic wave generators symmetrically arranged along the circumferential direction of the cavity; Preferably, in the third ultrasonic wave generating assembly, the spacings between the ultrasonic wave generators are the same; Preferably, the atomization device is an ultrasonic oscillation atomizer.

3. The spray pyrolysis device according to claim 1 or 2, characterized in that: The supply unit is used to store and supply the salt solution to the spray unit.

4. The spray pyrolysis device according to any one of claims 1 to 3, characterized in that: The ignition device is an ignition burner.

5. The spray pyrolysis device according to any one of claims 1 to 4, characterized in that: The spray pyrolysis device further comprises a dechlorinator, the inlet of which is connected to the outlet of the pyrolysis unit.

6. A method for preparing a ternary cathode precursor using the spray pyrolysis device according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: (1) supplying a chloride salt solution of a ternary positive electrode precursor to a spray unit through a feeding unit, heating the solution through ultrasonic action of the spray unit, and increasing the temperatures of a first unit, a second unit, and a third unit in a cavity of the spray unit in sequence to obtain a heated chloride salt solution; (2) atomizing the heated chloride salt solution using an atomizing device to obtain an atomized liquid; (3) Turn on the ignition device, ignite the atomized liquid, and perform thermal decomposition to obtain a ternary cathode precursor.

7. The method according to claim 6, characterized in that The chloride salt solution of the ternary positive electrode precursor includes lithium salt, nickel chloride, cobalt chloride and manganese chloride, wherein the ratio of the molar amount of lithium element to the total molar amount of the nickel element, cobalt element and manganese element is (1-1.1):1; Preferably, the lithium salt is at least one of lithium nitrate, lithium hydroxide, lithium nitrate and lithium chloride, preferably lithium chloride.

8. The method according to claim 6 or 7, characterized in that: The liquid inlet pressure of the atomizing device in the spray unit is 1 bar to 3 bar; Preferably, the liquid inlet speed of the atomizing device in the spray unit is 0.1 m / s. 3 / h-3.0m 3 / h; Preferably, the jet pressure of the atomizing device in the spray unit is 0.3MPa-0.8MPa; Preferably, the atomized liquid is brought into the pyrolysis unit by a carrier gas, and the carrier gas includes at least one of dry compressed air, oxygen or argon; Preferably, the flow rate of the carrier gas is 40 m / s. 3 / h-200m 3 / h.

9. The method according to any one of claims 6 to 8, characterized in that: In the spray unit, the temperature in the first unit is 50°C-200°C, the temperature in the second unit is 200°C-550°C, and the temperature in the third unit is 500°C-800°C; Preferably, the output power P1 of the first unit is 2.0kW-2.5kW, the output power P2 of the second unit is 2.7kW-2.9kW, and the output power of the third unit is 3.0kW-4.0kW; Preferably, the pyrolysis temperature is 750°C-1200°C; Preferably, the heating rate of the pyrolysis is 1°C / min-10°C / min; Preferably, the pyrolysis time is 5h-30h.

10. The method according to any one of claims 6 to 9, characterized in that: The method further comprises removing chlorine from the pyrolyzed product using a dechlorinator; Preferably, the temperature in the dechlorinator is 400°C-900°C.

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