Ternary precursor concentration reaction all-in-one machine with rotary filter element and anti-accumulation method of ternary precursor concentration reaction all-in-one machine

Abstract

The invention discloses a ternary precursor concentration and reaction all-in-one machine with a rotary filter element and an anti-accumulation method of the ternary precursor concentration and reaction all-in-one machine. The ternary precursor concentration and reaction all-in-one machine is suitable for a slurry solid extraction process in a wet coprecipitation preparation process of a lithium ion battery positive electrode material precursor. The all-in-one machine comprises a reaction kettle and a concentration module, the concentration module is provided with a filter element group capable of rotating around a long shaft, the filter element group is connected with a magnetic coupler through a hollow driving shaft, and a spiral flow guide groove is formed in the surface of a filter element. In the operation process, the filter element set rotates at the rotating speed of 50-120 rpm, particles on the surfaces of the filter elements are continuously stripped under the action of centrifugal force, meanwhile, filtrate is guided out through the hollow shaft, and accumulation on the surfaces of the filter elements is effectively prevented. Experiments show that the structure can prolong the reverse blowing period from 2 hours to 24 hours, the crystal breakage rate is reduced from 5.3% to 0.28%, and the filtration flux stability and the product quality are remarkably improved. The device is compact in structure, high in operation continuity and suitable for efficient concentration and solid extraction scenes of high-solid-content and fine-particle slurry.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery material preparation technology, specifically to a ternary precursor concentration reaction integrated machine with a rotating filter element and its anti-stacking method. Background Technology

[0002] Lithium-ion batteries, as a highly efficient energy storage technology, have been widely used in various fields such as electric vehicles, consumer electronics, and energy storage power stations. Especially in the field of new energy vehicles, in order to meet the demand for long driving range, lithium-ion batteries not only need to have high energy density, but also good stability and safety.

[0003] As a key component of lithium-ion batteries, the morphology, purity, and structural consistency of cathode precursors directly determine the performance of the final cathode material. Preparing high-quality precursors can not only effectively improve the specific capacity of lithium-ion batteries but also extend their cycle life and thermal stability.

[0004] Currently, the industry commonly uses wet co-precipitation processes to prepare ternary cathode material precursors (such as nickel-cobalt-manganese hydroxide, nickel-manganese, and nickel-manganese-aluminum). This process can be divided into batch production and continuous production based on the operation mode. Among them, the batch process is widely used in the preparation of mid-to-high-end ternary cathode material precursors due to its advantages in controlling crystal growth rate, improving the sphericity of secondary particles, and reducing particle size distribution.

[0005] In batch production, solid-liquid separation and slurry consolidation are required after the reaction to achieve the target solids concentration. Thickeners are typically used for this consolidation process. However, traditional thickeners face the following technical bottlenecks when processing cathode material precursor slurries:

[0006] 1. Slurry characteristics are not conducive to filtration: The precursor slurry has a high solid content (15% to 70%) and fine particles (50 to 300 nm), which makes it easy to form a dense filter cake on the surface of the filter element during the filtration process; the flux declines severely: the accumulation of filter cake causes the filtration resistance to rise rapidly, and the filtration flux drops significantly within a few hours, which seriously affects the process efficiency.

[0017] 2. Frequent backflushing and process interruption: In order to maintain the throughput, the equipment needs to be backflushed and cleaned frequently, which is complicated and disrupts the continuity of the reaction; product quality is damaged: the long-term accumulation of slurry on the filter element surface can easily lead to crystal breakage and increased particle size distribution, which in turn affects the synthesis quality of the cathode material precursor.

[0018] While existing technologies have attempted to introduce external stirring, airflow disturbance, or improve the feeding method to alleviate the filter element clogging problem, most solutions have failed to fundamentally resolve the core technical contradiction of "slurry accumulation on the filter element surface".

[0019] Therefore, there is an urgent need for a concentration equipment structure and process that can effectively suppress filter surface buildup, extend backflushing cycles, stabilize throughput, and ensure product structural integrity, in order to meet the needs of high-performance lithium battery precursor production. Summary of the Invention

[0020] The technical problem to be solved by the present invention is to overcome the existing defects and provide a ternary precursor concentration reaction integrated machine with rotating filter element and its anti-accumulation method. Its main function is to eliminate particle accumulation on the surface of filter element, realize continuous and efficient filtration, protect the integrity of precursor crystals, and improve the quality of precursor synthesis, which can effectively solve the problems in the background technology.

[0021] To achieve the above objectives, the present invention provides the following technical solution: a ternary precursor concentration and reaction integrated machine with rotating filter element and its anti-accumulation method, comprising a reaction vessel and a concentration module. The concentration module includes a hollow drive shaft and a filter element assembly. The filter element assembly is arranged in the circumferential direction of the hollow drive shaft and can rotate around the length direction of the hollow drive shaft. The inner cavity of the filter element assembly is connected to the hollow channel of the hollow drive shaft. The filtered filtrate flows into the hollow drive shaft through the inner cavity of the filter element and is discharged through the outlet of the hollow drive shaft. The filter element assembly can rotate around its long axis, i.e., the axial direction defined by the hollow drive shaft, to achieve continuous centrifugal cleaning of the filter element surface and inhibit material accumulation. The filter element assembly is connected to a rotating power device through the hollow drive shaft, and the linear velocity of the filter element surface is ≥0.5m / s. The filter element assembly is radially distributed. The center distance between adjacent filter elements in the filter element assembly is 1.2-1.5 times the diameter of the filter element. The filter element surface is provided with a spiral guide groove with an inclination angle of 15°-30° and a groove depth of 0.5-1.2mm.

[0022] Furthermore, the rotational power device is a magnetic coupler, which includes an inner rotor fixed to the hollow drive shaft. The magnetic coupler drives the hollow drive shaft to rotate through the inner rotor.

[0023] Furthermore, the filter element material of the filter cartridge is zirconium oxide or alumina, and the filter element is a porous ceramic filter tube with a pore size of 0.1-0.5 μm.

[0024] Furthermore, a gap is formed between the filter element of the filter assembly and the baffle installed on its outer side, and the width of the gap is 10 to 20 mm.

[0025] The baffle is located outside the filter cartridge assembly and is arranged around the filter cartridge to restrict the radial flow of the reaction slurry. The distance between the outer surface of the filter cartridge and the baffle is set to 10-20 mm to ensure that the slurry forms a flow field with a sufficient velocity gradient when passing through the surface of the filter cartridge, thereby improving filtration efficiency and slowing down filter cake accumulation.

[0026] During the co-precipitation reaction, the reaction slurry flows tangentially into the filter element area within the concentration module. The filter element assembly rotates around the long axis of the hollow drive shaft at a speed of 50–120 rpm. The centrifugal force generated by the rotation acts on the slurry on the outside of the filter element, causing solid particles to move away from the filter element surface and effectively inhibiting the formation of filter cake on the outer wall of the filter element. At the same time, the filter element is equipped with a drainage channel connected to the negative pressure system. Under the negative pressure drive, the liquid phase in the slurry passes through the filter element wall into the inner cavity of the filter element and is discharged along the internal channel of the hollow drive shaft. After being collected at the filtrate outlet, the high-concentration slurry after filtration is returned to the reactor, realizing continuous concentration and circulation of the slurry.

[0027] Furthermore, the method for preventing accumulation in the integrated ternary precursor concentration reactor with rotating filter element includes the following steps:

[0028] Step 1: Start the rotary power unit to make the filter element assembly rotate around the long axis of the hollow drive shaft at a speed of 50-120 rpm;

[0029] Step 2: Input the ternary cathode material precursor slurry into the filter element area at a tangential flow rate of 0.5-2 m / s;

[0030] Step 3: The particles in the slurry are detached from the outer surface of the filter element under the action of centrifugal force to prevent them from accumulating and forming a filter cake;

[0031] Step 4: After the filtrate passes through the filter element and enters its inner cavity, it is discharged through the internal channel of the hollow drive shaft, and the concentrated slurry is returned to the reactor to continue participating in the reaction.

[0032] In step one, the surface linear velocity of the filter element is maintained at 0.8–1.5 m / s.

[0033] The centrifugal force mentioned in step three is generated by the rotation of the filter element, and its direction is radial away from the axis of rotation. Its magnitude satisfies the following: Where: m is the mass of the slurry particles; ω is the angular velocity vector of the filter element; Let be the position vector of the particle relative to the rotation axis.

[0034] In the integrated concentration and reaction apparatus of this invention, the filter element assembly rotates around its long axis at a speed of 50–120 rpm. In the rotating reference frame, the slurry particles located on the outer side of the filter element will be subjected to centrifugal inertial force, which can be expressed by the formula... express;

[0035] The force is always directed radially away from the axis of rotation, causing solid particles in the slurry to be continuously stripped from the filter element surface during rotation, preventing filter cake buildup on the outer wall of the filter element. The presence of this centrifugal force enhances the particle separation capability during filtration, and works in synergy with the spiral guide grooves on the filter element surface. This not only extends the backflushing cycle and reduces flux attenuation, but also significantly reduces the breakage rate of product crystals, thereby ensuring the stability of the concentration and solidification process and product quality.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] 1. This invention successfully solves the problem of slurry accumulation on the surface of filter elements in traditional thickening equipment through the design of the filter element structure and movement mode. The filter element structure, which can rotate around its long axis, generates a stable centrifugal force field during operation, causing particles in the slurry to move away from the filter element surface during flow. Furthermore, a spiral guide groove is provided on the outer surface of the filter element to induce local turbulence in the fluid, further enhancing particle disturbance and desorption. In the embodiment, the filter cake thickness on the filter element surface is significantly reduced from 0.52 mm in the comparative example to 0.08 mm, fully verifying the technical advantages of this invention in dynamic peeling and surface self-cleaning capabilities, ensuring the stability of filtration flux during long-term operation.

[0038] 2. This invention effectively prevents filter cake accumulation and keeps the filter surface clean by using a rotating filter element and centrifugal peeling mechanism. Compared with traditional static filter elements that need to be backflushed every 1 to 2 hours, the backflushing cycle of this invention can be extended to more than 24 hours, and the backflushing frequency is reduced by 90%, which significantly improves the continuous operation capability and automation level of the equipment and is suitable for continuous production scenarios with high stability requirements.

[0039] 3. This invention effectively reduces the risk of crystal breakage by reducing accumulation and backflush interference; in the embodiment, the crystal breakage rate is reduced to 0.28%, which is far lower than the 5.3% of traditional equipment; the equipment structural parameters can be flexibly adjusted to adapt to a variety of ternary precursor slurries, ensuring the uniformity of product particle size and the integrity of crystal form, and improving the electrochemical performance of the final material. Attached Figure Description

[0040] Figure 1 This is a front view structural diagram of the present invention;

[0041] Figure 2 This is a top view of the structure of the present invention.

[0042] In the diagram: 1 hollow drive shaft, 2 filter element group, 3 magnetic coupler, 4 inner rotor, 5 spiral guide groove. Detailed Implementation

[0043] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0044] Example 1

[0045] Please see Figure 1-2 This invention provides a technical solution: a ternary precursor concentration reactor with a rotating filter element and its anti-accumulation method. In this embodiment, the ternary precursor concentration reactor with a rotating filter element of this invention is used, and a comparative experiment is conducted with the traditional static filter element concentration equipment in the comparative example. Except for the filter element structure, the other equipment parameters are completely identical; the specific configuration is as follows:

[0046] Filter material: Zirconia ceramic;

[0047] Filter element size: Φ80mm×1200mm;

[0048] Average pore size: 0.2 μm;

[0049] Filter cartridge quantity and arrangement: radially evenly distributed;

[0050] Drive unit: 1.5kW servo motor, with matching magnetic coupler 3;

[0051] Filter cartridge rotation speed: 80 rpm (corresponding to a surface linear velocity of 1.2 m / s);

[0052] The angle of the guide channel is 20° in the example and 0° in the comparative example (without guide channel).

[0053] The ternary cathode material precursor slurry was introduced into the equipment for continuous filtration. The initial solid content was approximately 40%, and solid-liquid separation was achieved through negative pressure. The experiment ran continuously for 4 hours, and the following key performance indicators were tested:

[0054] Table 1 Comparison of results between the examples and comparative examples.

[0055] project Comparative example (static filter element) Example (Rotating Filter Cartridge) <![CDATA[Initial flux (L / m 2 h)]]> 520 510 Flux after 4 hours 220(↓58％) 465(↓9％) Backflush interval (h) 2 24 Filter cake thickness (mm) 0.52 0.08 Product breakage rate (%) 5.3 0.28

[0056] As shown in Table 1, with similar initial flux, the flux of the comparative example decreased by 58% within 4 hours, while the flux of the embodiment of the present invention decreased by only 9%, significantly improving the stability of the filtration process; the filter cake thickness on the filter element surface decreased from 0.52 mm to 0.08 mm, effectively avoiding particle accumulation; the backflushing cycle was extended from 2 hours to 24 hours, significantly improving the continuous operation capability of the equipment; and the crystal breakage rate was significantly reduced, demonstrating the protective effect of the present invention on the precursor crystal structure.

[0057] To optimize the structure of the spiral guide channel 5 in the filter element, the effects of different guide channel inclination angles on the filtration effect and crystal breakage rate were tested under the same operating conditions. The results are as follows:

[0058] Table 2. Experimental Results of Optimization of Guide Channel Inclination Angle

[0059] Inclination angle (°) Flux maintenance rate (8h) Crystal breakage rate (%) 0° 84％ 0.35％ 15° 91％ 0.25％ 20° 95％ 0.22％ 30° 88％ 0.40％

[0060] The results show that when the inclination angle of the spiral guide channel 5 is set to 20°, the throughput maintenance rate is the highest, the crystal breakage rate is the lowest, and the overall performance is the best. The spiral guide channel 5 can guide the slurry to move along the spiral path, and under the action of filter element rotation and centrifugal force, it can further enhance the particle stripping effect and effectively suppress filter cake formation.

[0061] In summary, the embodiments verify that the rotary filter element structure and its matching guide groove design proposed in this invention have significant advantages in improving filtration efficiency, reducing breakage rate, and extending backflushing cycle.

[0062] In addition to the preferred embodiments described above, the present invention can also be modified in various ways to suit different process requirements, including but not limited to the following:

[0063] Filter material variations: In addition to zirconium oxide, alumina or other porous ceramic materials with acid and alkali resistance and wear resistance can also be selected to meet the corrosion resistance requirements of different reaction systems.

[0064] Adjustment of guide channel parameters: The inclination angle of the guide channel can be adjusted to between 15° and 25° according to the viscosity of the slurry and the characteristics of the particles. The depth of the channel can be optimized within the range of 0.5 to 1.2 mm to obtain the best turbulence effect and particle stripping efficiency.

[0065] Rotation method replacement: In some operating conditions, a direct-drive servo motor can be used to replace the magnetic coupler to achieve the rotation of the filter cartridge, which is suitable for scenarios with high requirements for high-precision drive control.

[0066] Hollow shaft liquid discharge mode expansion: The hollow drive shaft can be equipped with a flow meter, filter pressure monitoring device and automatic liquid discharge valve to realize the monitoring and precise control of filtrate flow rate and improve the system intelligence level.

[0067] Modular structure design: The filter cartridge can be designed as a detachable module, which is convenient for maintenance and replacement, and can adapt to the production requirements of different batches, realizing flexible assembly of the integrated machine.

[0068] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A ternary precursor concentration reactor with a rotating filter element, comprising a reactor and a concentration module, characterized in that: The concentration module includes a hollow drive shaft (1) and a filter element group (2). The filter element group (2) is located in the circumferential direction of the hollow drive shaft (1) and can rotate around the length direction of the hollow drive shaft (1). The filter element group (2) is connected to a rotational power device through the hollow drive shaft (1), and the surface linear velocity of the filter element is ≥0.5m / s. The filter element group (103) is radially distributed. The center distance between adjacent filter elements in the filter element group (103) is 1.2-1.5 times the diameter of the filter element. The surface of the filter element is provided with a spiral guide groove (5). The inclination angle of the spiral guide groove (5) is 15°-30° and the groove depth is 0.5-1.2mm.

2. The ternary precursor concentration and reaction integrated machine with rotating filter element according to claim 1, characterized in that: The rotational power device is a magnetic coupler (3), which includes an inner rotor (4) fixed to a hollow drive shaft.

3. The ternary precursor concentration and reaction integrated machine with rotating filter element according to claim 1, characterized in that: The filter element material of the filter element assembly (2) is zirconium oxide or alumina, and the filter element is a porous ceramic filter tube with a pore size of 0.1-0.5μm.

4. The ternary precursor concentration reaction integrated machine with rotating filter element according to claim 1, characterized in that: A gap is formed between the filter element of the filter element assembly (2) and the baffle provided on its outer side, and the width of the gap is 10 to 20 mm.

5. A method for preventing accumulation in a ternary precursor concentration and reaction integrated machine with a rotating filter element, characterized in that, The ternary precursor concentration reactor with rotating filter element as described in any one of claims 1-4 includes the following steps: Step 1: Start the rotary power device to make the filter element group rotate around the long axis of the hollow drive shaft (1) at a speed of 50-120 rpm; Step 2: Input the ternary cathode material precursor slurry into the filter element area at a tangential flow rate of 0.5-2 m / s; Step 3: The particles in the slurry are detached from the outer surface of the filter element under the action of centrifugal force to prevent them from accumulating and forming a filter cake; Step 4: After the filtrate passes through the filter element and enters its inner cavity, it is discharged through the internal channel of the hollow drive shaft (1), and the concentrated slurry is returned to the reactor to continue to participate in the reaction.

6. A method for preventing accumulation in a ternary precursor concentration and reaction integrated machine with a rotating filter element, characterized in that, In step one, the surface linear velocity of the filter element is maintained at 0.8–1.5 m / s.

7. A method for preventing accumulation in a ternary precursor concentration and reaction integrated machine with a rotating filter element, characterized in that, The centrifugal force mentioned in step three is generated by the rotation of the filter element, and its direction is radial away from the axis of rotation. Its magnitude satisfies the following: Where: m is the mass of the slurry particles; ω is the angular velocity vector of the filter element; Let be the position vector of the particle relative to the rotation axis.

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