Homogeneous sintering device, lithium iron manganese phosphate positive electrode material and suspension sintering method thereof

Abstract

A homogeneous sintering apparatus, relating to the field of battery material preparation technology, utilizes a turbine blade that rotates at high speed to generate an upward airflow. The blade tips of the turbine blade create extremely strong shear and impact fields, which can completely break up all passing material agglomerates, ensuring that the material re-enters the sintering chamber as single particles or micro-agglomerates. Simultaneously, tangential blowing from a nozzle array creates a spiral upward airflow, keeping the material in suspension and thus improving sintering consistency. Based on this homogeneous sintering apparatus, this invention also provides a lithium manganese iron phosphate cathode material and its suspension sintering method. This method can complete the crystallization and carbon coating of the material while ensuring complete material suspension, resulting in a more uniformly sintered lithium manganese iron phosphate cathode material. It solves problems such as material stratification, uneven carbon distribution, and differences in compaction density in existing sintering processes, and has significant practical value.

Description

Technical Field

[0001] This invention relates to the field of battery material preparation technology, and more specifically, to a homogeneous sintering apparatus, lithium manganese iron phosphate cathode material, and a suspension sintering method thereof. Background Technology

[0002] Lithium manganese iron phosphate (LiMn) x Fe 1-x PO4 (LMFP) is an olivine-type lithium-ion battery cathode material that combines the safety of LiFePO4 (LFP) with the high voltage advantage of LiMnPO4 (LMP). It is considered to be one of the core materials for the next generation of high-energy-density, low-cost power batteries.

[0003] Solid-state sintering is one of the main methods for preparing lithium manganese iron phosphate materials. It involves mixing and sintering lithium, manganese, iron, and phosphorus sources, followed by carbon coating using a carbon source. During sintering, a sagger is required to load the material, which can easily lead to problems such as material stratification, uneven carbon distribution, and differences in compaction density. Summary of the Invention

[0004] The purpose of this invention is to provide a homogeneous sintering apparatus that adopts a saggerless design, which can maintain the material in a suspended state during the sintering process and improve the uniformity of sintering.

[0005] Another objective of this invention is to provide a lithium manganese iron phosphate cathode material and its suspension sintering method, which uses the above-mentioned homogeneous sintering apparatus. This method is simple and convenient to operate, and can quickly and efficiently obtain lithium manganese iron phosphate cathode material with better sintering consistency.

[0006] The embodiments of the present invention are implemented as follows:

[0007] A homogeneous sintering apparatus includes a shell, an interior of which is formed a sintering cavity. A flow field generating device is disposed at the bottom of the sintering cavity. The flow field generating device includes a disc-shaped fixed disk, a material passage is disposed in the middle of the fixed disk, and a turbine fan blade is disposed in the material passage. Multiple nozzles are distributed on the upper surface of the fixed disk, and the multiple nozzles are arranged in a ring around the material passage to form a nozzle array. The nozzles are inclined upwards, and the projection of the nozzles on the upper surface of the fixed disk is aligned with the tangent direction of the ring in which they are located, and the multiple nozzles face the same direction.

[0008] Furthermore, in other preferred embodiments of the present invention, there are multiple nozzle arrays, which are spaced apart along the diameter direction of the fixed disk.

[0009] Furthermore, in other preferred embodiments of the present invention, the included angle between the nozzle and the upper surface of the fixed disc is 15~25°.

[0010] Furthermore, in other preferred embodiments of the present invention, one end of the nozzle is provided with a ball joint, and the upper surface of the fixing plate is provided with a ball socket fixing seat corresponding to the nozzle.

[0011] Furthermore, in other preferred embodiments of the present invention, the flow field generating device further includes an adjusting disk disposed on the upper surface of the fixed disk, the adjusting disk being coaxially disposed with the fixed disk and being rotatable relative to the fixed disk; the adjusting disk is provided with a plurality of guide oblique holes spaced apart along its circumference, the ball socket fixing seat being located inside the guide oblique holes, and the nozzle extending out from the guide oblique holes.

[0012] Furthermore, in other preferred embodiments of the present invention, the homogenizing sintering apparatus further includes a heating unit, which includes a heating resistor disposed on the side wall of the sintering cavity and an infrared radiation array disposed on the top of the sintering cavity.

[0013] Furthermore, in other preferred embodiments of the present invention, the homogeneous sintering apparatus further includes an acoustic wave-assisted dispersion unit, which includes a piezoelectric ceramic transducer disposed on the side wall of the sintering cavity.

[0014] Furthermore, in other preferred embodiments of the present invention, the homogenizing sintering apparatus further includes a graded collection unit disposed at the discharge port, the graded collection unit including a negatively charged copper plate for adsorbing positively charged particles and a positively charged titanium plate for collecting negatively charged particles.

[0015] A suspension sintering method for lithium manganese iron phosphate cathode material, employing the aforementioned homogeneous sintering apparatus, includes:

[0016] Iron, lithium, manganese, phosphorus and carbon sources are mixed and added to the sintering chamber, and the turbine fan blades are turned on to form an upward airflow;

[0017] Open the nozzle and inject nitrogen gas to form a spiral upward flow field, which raises the temperature inside the sintering chamber and completes one stage of sintering.

[0018] The gas injected into the nozzle was changed to a mixture of nitrogen, carbon monoxide and hydrogen to complete the two-stage sintering.

[0019] After sintering is complete, heating is stopped, and the gas injected into the nozzle is changed to nitrogen for cooling.

[0020] After cooling is complete, the rotation direction of the turbine blades is changed to create a downward airflow, which guides the lithium manganese iron phosphate material out.

[0021] A lithium manganese iron phosphate cathode material is prepared by the suspension sintering method of the above-mentioned lithium manganese iron phosphate cathode material.

[0022] The beneficial effects of the embodiments of the present invention are:

[0023] This invention provides a homogeneous sintering apparatus. This apparatus uses high-speed rotating turbine blades to create an upward airflow. The blade tips generate extremely strong shear and impact fields, which thoroughly break up all passing material agglomerates, ensuring that the material re-enters the sintering chamber as single particles or micro-agglomerates. Simultaneously, tangential blowing from a nozzle array creates a spiral upward airflow, keeping the material in suspension and improving sintering consistency. Based on this homogeneous sintering apparatus, this invention also provides a lithium manganese iron phosphate cathode material and its suspension sintering method. This method can complete the crystallization and carbon coating of the material while ensuring complete material suspension, resulting in a more uniformly sintered lithium manganese iron phosphate cathode material. This solves problems such as material stratification, uneven carbon distribution, and differences in compaction density in existing sintering processes, and has significant practical value. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a cross-sectional view of a homogeneous sintering apparatus provided in the first embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a flow field generation device for a homogeneous sintering apparatus provided in the first embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the fixed disk of a homogeneous sintering apparatus provided in the first embodiment of the present invention;

[0028] Figure 4 This is a partial cross-sectional view of the flow field generation device of a homogeneous sintering apparatus provided in the first embodiment of the present invention.

[0029] Icons: 100-Homogeneous sintering device; 110-Shell; 111-Sintering chamber; 112-Feed inlet; 113-Discharge outlet; 120-Flow field generating device; 121-Fixed plate; 1211-Material passage; 1212-Turbine fan blade; 1213-Nozzle; 1214-Ball socket fixing seat; 122-Adjusting plate; 1221-Guide oblique hole. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] Example 1

[0036] This embodiment provides a homogeneous sintering apparatus 100, referring to... Figure 1 As shown, it includes a housing 110, a sintering cavity 111 is formed inside the housing 110, a feed inlet 112 is provided at the top of the sintering cavity 111, a discharge outlet 113 is provided at the bottom, and a flow field generating device 120 is provided at the bottom of the sintering cavity 111.

[0037] Among them, such as Figure 2 and Figure 3 As shown, the flow field generating device 120 includes a disc-shaped fixed disk 121. A material passage 1211 is provided in the center of the fixed disk 121, connecting to a discharge port 113. A turbine fan blade 1212 is installed within the material passage 1211. Multiple nozzles 1213 are distributed on the upper surface of the fixed disk 121, forming a nozzle array around the material passage 1211 in a ring shape. The nozzles 1213 are inclined upwards, and their projections on the upper surface of the fixed disk 121 are aligned with the tangential direction of their respective rings. Furthermore, the multiple nozzles 1213 face the same direction. It should be noted that "facing the same direction" here means simultaneously facing clockwise or counterclockwise, thus forming a tangential rotating airflow. In use, the turbine fan blade 1212 is activated to create an upward airflow, while the nozzles 1213 are activated to sweep along the tangential direction, forming a spiral upward airflow. When the material enters the sintering chamber 111, the small material will be suspended in the sintering chamber 111 under the action of the rising airflow, while the large material will fall into the material passage 1211 and be broken by the shearing and impact of the turbine fan blades 1212. The material will then be blown back into the sintering chamber 111 in the form of single particles or small agglomerates by the rising airflow.

[0038] The fixed plate 121 has a hollow internal structure. Gas is introduced into the fixed plate 121 through a single air intake pipe, and then the airflow is distributed to all nozzles 1213 simultaneously. This facilitates unified control of the air intake flow rate.

[0039] Furthermore, such as Figure 3As shown, there are multiple nozzle arrays 1213, which are spaced apart along the diameter of the fixed disk 121. In this embodiment, three nozzle arrays 1213 are provided, arranged concentrically on the outside of the material passage 1211. The three nozzle arrays 1213 increase the purging area, and the resulting airflow can better achieve the suspension effect.

[0040] The included angle between the nozzle 1213 and the upper surface of the fixed plate 121 is 15~25°. Optionally, one end of the nozzle 1213 is provided with a ball joint, and the upper surface of the fixed plate 121 is provided with a ball socket fixing seat 1214 corresponding to the nozzle 1213. The angle of the nozzle 1213 can be adjusted by means of ball joint connection.

[0041] Optionally, such as Figure 2 and Figure 4 As shown, the flow field generating device 120 also includes an adjusting disk 122 disposed on the upper surface of the fixed disk 121. The adjusting disk 122 is coaxially disposed with the fixed disk 121 and can rotate relative to the fixed disk 121. The adjusting disk 122 is provided with a plurality of guide inclined holes 1221 spaced apart along its circumference. The ball socket fixing seat 1214 is located in the guide inclined holes 1221, and the nozzle 1213 extends out from the guide inclined holes 1221. Taking the view in the figure as an example, one side wall of the guide inclined hole 1221 (left side in the figure) extends upward to above the nozzle 1213. When the adjusting disk 122 rotates to the right in the figure, the left side wall contacts the nozzle 1213 and presses it down to reduce the included angle. Conversely, when the adjusting disk 122 rotates to the left in the figure, the right side wall of the guide inclined hole 1221 pushes up the nozzle 1213 to increase the included angle. The rotation of the adjustment disc 122 can be driven by a motor. The specific connection method can refer to the existing technology. For example, gear teeth can be set on the edge of the adjustment disc 122, and then the rack can drive it to rotate in a small range. The included angle of all nozzles 1213 can be adjusted synchronously by adding electronic control.

[0042] Furthermore, the homogenizing sintering apparatus 100 also includes a heating unit, which comprises a heating resistor disposed on the side wall of the sintering cavity 111 and an infrared radiation array disposed on the top of the sintering cavity 111. Traditional sintering processes typically employ resistance heating, a method of contact-based heat conduction. However, in this embodiment of the invention, because the material is in a suspended state, heat conduction attenuates, resulting in insufficient temperature at the center of the sintering cavity 111. Therefore, this invention employs an infrared radiation array to compensate for the temperature in the central region through radiative heat, thereby achieving better temperature control. The heating resistor serves as the main heating system, utilizing multi-point insertion thermocouples to achieve temperature control of ±3℃, and in conjunction with the top infrared radiation array, compensates for the central temperature gradient, achieving an overall thermal gradient of ±1℃ for the entire equipment cavity.

[0043] Optionally, the homogeneous sintering apparatus 100 further includes an acoustic wave-assisted dispersion unit, which includes a piezoelectric ceramic transducer disposed on the side wall of the sintering chamber 111. The piezoelectric ceramic transducer can generate a standing wave field, which, in conjunction with the airflow, achieves a dual effect of "fluidization-breakup".

[0044] Furthermore, the homogenizing sintering apparatus 100 also includes a graded collection unit located at the discharge port 113. The graded collection unit includes a negatively charged copper plate for adsorbing positively charged particles and a positively charged titanium plate for collecting negatively charged particles. During the discharge process, positively charged particles (materials not fully carbon-coated) are adsorbed by the copper plate, negatively charged particles (materials fully carbon-coated) are adsorbed by the titanium plate, while neutral particles are not adsorbed and can be separated by a cyclone separator and returned to the sintering chamber 111 for processing.

[0045] Example 2

[0046] This embodiment provides a lithium manganese iron phosphate cathode material, which is prepared by suspension sintering using the aforementioned homogeneous sintering apparatus 100. The preparation method includes:

[0047] S1. Iron source, lithium source, manganese source, phosphorus source and carbon source are mixed and added to sintering chamber 111, and turbine fan blades 1212 are turned on to form an upward airflow.

[0048] S2. Open nozzle 1213 to inject nitrogen gas, forming a spiral upward flow field, raising the temperature inside sintering chamber 111, and completing a sintering stage.

[0049] Optionally, the airflow velocity of nozzle 1213 is controlled at 3~5 m / s to achieve a better suspension effect. Nitrogen, in addition to serving as a carrier gas, can also prevent the carbon source from being oxidized. The jetting from nozzle 1213 can be in pulse form, switching at a frequency of 3~5 times per second.

[0050] During the sintering process, an acoustic-assisted dispersion unit is used for assisted crushing, utilizing a piezoelectric ceramic transducer (40kHz, power density 0.5W / cm³). 3 This generates a standing wave field, with ultrasonic power controlled between 1 and 5 kW and a sound pressure gradient > 10. 4 Pa / m, better shearing of aggregates. Employing a pulsed operating mode: 2s operation followed by a 1s interval, to avoid resonant agglomeration of particles.

[0051] S3. Change the gas injected into nozzle 1213 to a mixture of nitrogen, carbon monoxide and hydrogen to complete the second-stage sintering.

[0052] The airflow velocity is controlled at 3~5 m / s. Nitrogen is used as the carrier gas, carbon monoxide as the reducing agent, and hydrogen as the carbon chain regulator. Adding carbon monoxide and hydrogen during crystallization can promote the graphitization of carbon source and inhibit the reduction of manganese.

[0053] S4. After sintering is complete, stop heating and change the gas injected into nozzle 1213 to nitrogen for cooling.

[0054] S5. After cooling is complete, open the discharge port 113, change the rotation direction of the turbine fan blades 1212 to form a downward airflow, and guide the lithium manganese iron phosphate material to be discharged.

[0055] At this time, the angle of the nozzle 1213 can be adjusted to lower the airflow, changing the upward blowing to blowing towards the side wall of the sintering chamber 111. The rising spiral airflow then becomes vertical convection and is guided out by the turbine blades 1212.

[0056] The discharge port 113 collects materials through a graded collection unit. Positively charged particles (materials not fully carbon-coated) are adsorbed by copper plates, negatively charged particles (materials fully carbon-coated) are adsorbed by titanium plates, while neutral particles are not adsorbed and can be separated by a cyclone separator and returned to the sintering chamber 111 for processing.

[0057] In summary, this invention provides a homogeneous sintering apparatus 100. This apparatus 100 generates an upward airflow through the high-speed rotation of turbine blades 1212. The tips of the turbine blades 1212 create extremely strong shear and impact fields, which can completely break up all passing material agglomerates, ensuring that the material re-enters the sintering chamber 111 as single particles or micro-agglomerates. Simultaneously, the tangential blowing of the nozzle array 1213 creates a spiral upward airflow, keeping the material in suspension and thus improving sintering consistency. Based on this homogeneous sintering apparatus 100, this invention also provides a lithium manganese iron phosphate cathode material and its suspension sintering method. This method can complete the crystallization and carbon coating of the material while ensuring complete material suspension, resulting in a more uniformly sintered lithium manganese iron phosphate cathode material. This solves problems such as material stratification, uneven carbon distribution, and differences in compaction density in existing sintering processes, and has significant practical value.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A homogeneous sintering apparatus, characterized in that, The device includes a shell, the interior of which is formed a sintering cavity. A flow field generating device is disposed at the bottom of the sintering cavity. The flow field generating device includes a disc-shaped fixed disk. A material passage is disposed in the middle of the fixed disk, and a turbine fan blade is disposed in the material passage. Multiple nozzles are distributed on the upper surface of the fixed disk. The multiple nozzles are arranged in a ring around the material passage to form a nozzle array. The nozzles are inclined upwards, and the projection of the nozzles on the upper surface of the fixed disk is tangential to the ring in which they are located, and the multiple nozzles face the same direction. One end of the nozzle is provided with a ball joint, and the upper surface of the fixing plate is provided with a ball socket fixing seat corresponding to each nozzle. The flow field generating device further includes an adjusting disk disposed on the upper surface of the fixed disk. The adjusting disk is coaxially disposed with the fixed disk and can rotate relative to the fixed disk. The adjusting disk is provided with a plurality of guide oblique holes at intervals along its circumference. The ball socket fixing seat is located in the guide oblique holes, and the nozzle extends out from the guide oblique holes.

2. The homogeneous sintering apparatus according to claim 1, characterized in that, The number of nozzle arrays is multiple, and the multiple nozzle arrays are spaced apart along the diameter direction of the fixed disk.

3. The homogeneous sintering apparatus according to claim 2, characterized in that, The angle between the nozzle and the upper surface of the fixed plate is 15~25°.

4. The homogeneous sintering apparatus according to claim 3, characterized in that, The homogeneous sintering apparatus further includes a heating unit, which includes a heating resistor disposed on the side wall of the sintering cavity and an infrared radiation array disposed on the top of the sintering cavity.

5. The homogeneous sintering apparatus according to claim 4, characterized in that, The homogeneous sintering apparatus further includes an acoustic wave-assisted dispersion unit, which includes a piezoelectric ceramic transducer disposed on the side wall of the sintering cavity.

6. The homogeneous sintering apparatus according to claim 5, characterized in that, The homogenized sintering apparatus further includes a graded collection unit located at the discharge port. The graded collection unit includes a negatively charged copper plate for adsorbing positively charged particles and a positively charged titanium plate for collecting negatively charged particles.

7. A suspension sintering method for lithium manganese iron phosphate cathode material, characterized in that, The homogeneous sintering apparatus according to any one of claims 1 to 6 includes: mixing an iron source, a lithium source, a manganese source, a phosphorus source, and a carbon source and adding them to the sintering chamber; turning on the turbine fan blades to form an upward airflow; opening the nozzles and injecting nitrogen gas to form a spiral upward flow field, raising the temperature inside the sintering chamber to complete the first stage of sintering; changing the gas injected into the nozzles to a mixture of nitrogen, carbon monoxide, and hydrogen gas to complete the second stage of sintering; after sintering, stopping heating and changing the gas injected into the nozzles to nitrogen gas for cooling; after cooling, changing the rotation direction of the turbine fan blades to form a downward airflow to guide the lithium manganese iron phosphate material out.

8. A lithium manganese iron phosphate cathode material, characterized in that, It is prepared by the suspension sintering method of lithium manganese iron phosphate cathode material as described in claim 7.

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