roller hearth kiln

Abstract

This application relates to the technical field of lithium iron phosphate production equipment, and discloses a roller kiln, including: a kiln body and a conveying mechanism. The kiln body includes a sintering chamber, and multiple baffles are spaced apart along the material conveying direction inside the sintering chamber. Multiple through holes are spaced apart on the baffles. The conveying mechanism is located at the bottom of the kiln body and is used to drive the material to move along the material conveying direction. The roller kiln provided by this application has multiple baffles in the sintering chamber and through holes on the baffles. The material moves with the conveying mechanism and enters the sintering chamber. Multiple static baffles are used to stir and disturb the material, and the through holes are used to guide the airflow disturbance, so that the airflow directly impacts the material. This can enhance the heat transfer in the sintering chamber and form a coupling mechanism of "thermal field-flow field-reaction field", thereby significantly enhancing the sintering process in the roller kiln, improving the consistency yield of the prepared lithium iron phosphate cathode material, and improving the compaction density and capacity of the lithium iron phosphate cathode material.

Description

Technical Field

[0001] This application relates to the field of lithium iron phosphate production equipment, specifically to roller kilns. Background Technology

[0002] Lithium iron phosphate (LiFePO4, LFP), as a core cathode material for power batteries, has captured over 60% of the lithium battery market due to its high safety, long cycle life, and low cost. The formation of the olivine crystal structure in lithium iron phosphate depends on the precise control of the sintering process, which requires meeting high standards.

[0003] The traditional sintering process of roller kilns mainly involves packaging spray-dried lithium iron phosphate powder into saggers, and then sending the saggers into the roller kiln for sintering. In order to ensure uniform heating of the powder, a stirring structure is usually set in the sintering chamber to stir the powder in the sagger. However, the lithium iron phosphate powder is in a piled-up state in the sagger, which easily leads to defects such as uneven lateral thermal field, sluggish atmosphere transfer, unbalanced heating of the powder, and uncontrolled micro-powder formation in the sintering chamber, resulting in a low uniformity pass rate of lithium iron phosphate cathode materials. Utility Model Content

[0004] This application provides a roller kiln to solve the problem that existing roller kilns, which package lithium iron phosphate powder into saggers for transportation and use a stirring structure for stirring, have a low yield rate of consistent lithium iron phosphate cathode materials.

[0005] This application provides a roller kiln, comprising: The kiln body includes a sintering cavity, wherein multiple baffles are spaced apart along the material conveying direction inside the sintering cavity, and multiple through holes are spaced apart on the baffles; The conveying mechanism is located at the bottom of the kiln body and is used to drive the material to move along the conveying direction.

[0006] In one optional embodiment, the kiln body further includes a preheating chamber located at the front end of the sintering chamber and a cooling chamber located at the rear end of the sintering chamber along the material conveying direction. The sintering cavity is inclined upward relative to the cooling cavity; And / or, the sintering cavity is inclined downward relative to the preheating cavity.

[0007] In one optional embodiment, the tilt angle of the sintering cavity is θ, satisfying 2°≤θ<90°.

[0008] In one alternative implementation, 15° ≤ θ ≤ 80°.

[0009] In one alternative implementation, 5°≤θ≤30°.

[0010] In one optional embodiment, the kiln body further includes a feeding chamber located at the front end of the preheating chamber and a discharging chamber located at the rear end of the cooling chamber along the material conveying direction.

[0011] In one alternative embodiment, the preheating chamber and the cooling chamber are horizontally distributed.

[0012] In one alternative embodiment, a gap is left between the bottom of the baffle and the transmission mechanism.

[0013] In one optional embodiment, the gap length between the bottom of the baffle and the transmission mechanism along the X direction is L1, and the height dimension of the sintering cavity along the X direction is L2, satisfying 0.1≤L1 / L2≤0.8.

[0014] In one alternative implementation, 0.1 ≤ L1 / L2 ≤ 0.45.

[0015] In one alternative embodiment, the top of the baffle is fixed to the top wall of the sintering chamber; And / or, the through hole includes a regular hole or an irregular hole, and the regular hole includes a round hole or a corrugated strip hole.

[0016] In one optional implementation, the transmission mechanism includes: Drive components; Multiple rollers are connected to the drive unit, and the multiple rollers are spaced apart at the bottom of the kiln body along the material conveying direction; A conveyor belt, fitted over the outside of the plurality of rollers, is used to place materials and move the materials along the conveying direction.

[0017] The technical solution of this application has the following advantages: 1. Multiple baffles are set in the sintering chamber, and through holes are opened on the baffles. The material moves with the conveying mechanism and enters the sintering chamber. The material passes through the through holes of multiple static baffles to achieve the stirring and disturbance function. At the same time, the through holes enhance the airflow disturbance, allowing the airflow to directly impact the material, strengthening the heat transfer in the sintering chamber, and forming a coupling mechanism of "thermal field-flow field-reaction field". High-quality lithium iron phosphate cathode material can be prepared in one sintering. It can significantly enhance the sintering process in the roller kiln, improve the consistency and pass rate of prepared lithium iron phosphate cathode material, and improve the compaction density and capacity of lithium iron phosphate cathode material.

[0018] 2. By setting the sintering chamber at a relative angle, when the material enters the sintering chamber, the material's own gravity, along with the baffles and the conveying mechanism, enables the material to move relative to each other within the sintering chamber, thereby significantly enhancing the momentum, heat, and mass transfer processes and reaction processes within the sintering chamber.

[0019] 3. By controlling L1 / L2 within a suitable range, a suitable material passage gap can be left between the baffle and the conveying mechanism, avoiding material accumulation at the bottom of the baffle and hindering internal heat transfer, which would lead to material heating imbalance and thus improve sintering quality.

[0020] 4. The conveying mechanism uses a dense, non-porous conveyor belt to transport materials, eliminating the need for traditional saggers and preventing material accumulation inside the saggers. This ensures uniform material flow and improves sintering quality. Furthermore, it simplifies the conveying structure and reduces operating costs, making it easier to promote. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the sintering chamber of the roller kiln in a horizontal position according to an embodiment of this application; Figure 2 This is a schematic diagram of the sintering chamber of the roller kiln in an inclined position according to an embodiment of this application; Figure 3 This is a front view of the roller kiln according to an embodiment of this application; Figure 4 This is a schematic diagram of the structure of the baffle of the roller kiln according to an embodiment of this application; Figure 5 This is a schematic diagram of another type of baffle in a roller kiln according to an embodiment of this application; Figure 6 This is a schematic diagram of the conveying mechanism of the roller kiln according to an embodiment of this application; Figure 7 This is a schematic diagram of the sintering chamber of the roller kiln according to an embodiment of this application.

[0023] Explanation of reference numerals in the attached figures: 1. Kiln body; 101. Sintering chamber; 1011. Baffle; 1012. Through hole; 102. Preheating chamber; 103. Cooling chamber; 104. Feeding chamber; 105. Discharge chamber; 2. Conveying mechanism; 201. Roller; 202. Conveyor belt. Detailed Implementation

[0024] The technical solutions of the embodiments of this application 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 this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion. In the description of the embodiments in this application, "a plurality of" means two (including two) or more, unless otherwise expressly specified. The reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0027] In the description of the embodiments of this application, the technical terms "length", "width", "thickness", "upper", "lower", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this application 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 the embodiments of this application.

[0028] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms "installation," "connection," "joining," "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 mechanical connection or an electrical connection; 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. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0029] The inventors discovered that in the process of preparing lithium iron phosphate cathode materials, traditional roller kilns inevitably experience edge heat dissipation effects and radiation dead zones due to the influence of the sagger and stirring structure. This leads to defects such as uneven lateral thermal fields, causing significant temperature differences in the material during sintering and reducing compaction density. Furthermore, the static transport of materials within the sagger and their accumulation hinder internal heat transfer, resulting in thermal imbalance. Traditional roller kilns employ a laminar flow-dominated gas flow mode, which suffers from delayed atmosphere transfer. Insufficient airflow disturbance also easily leads to particle agglomeration, resulting in uncontrolled micro-powder formation. Ultimately, this results in a consistency pass rate of less than 85.7% for lithium iron phosphate cathode materials, far below the 99.5% requirement for power batteries.

[0030] In order to solve the problems existing in the above-mentioned related technologies, such as Figures 1 to 3 As shown, a roller kiln is provided, mainly comprising: a kiln body 1 and a conveying mechanism 2. The kiln body 1 includes a sintering chamber 101, and multiple baffles 1011 are spaced apart along the material conveying direction inside the sintering chamber 101. Multiple through holes 1012 are spaced apart on the baffles 1011. The conveying mechanism 2 is located at the bottom of the kiln body 1 and is used to drive the material to move along the material conveying direction.

[0031] The roller kiln provided in this embodiment features multiple baffles 1011 within the sintering chamber 101, with through holes 1012 formed on the baffles 1011. Material moves with the conveying mechanism 2 and enters the sintering chamber 101. The material passes through the through holes 1012 of the multiple static baffles 1011, achieving a stirring and agitation function. Simultaneously, the through holes 1012 enhance airflow agitation, allowing the airflow to directly impact the material, strengthening heat transfer within the sintering chamber 101, and forming a coupling mechanism of "thermal field-flow field-reaction field." This allows for the preparation of high-quality lithium iron phosphate cathode materials in a single sintering process, significantly enhancing the sintering process within the roller kiln, improving the consistency and yield rate of prepared lithium iron phosphate cathode materials, and increasing the compaction density and capacity of the lithium iron phosphate cathode materials.

[0032] Compared to the traditional roller kiln which uses a stirring structure to agitate materials, the embodiments of this application use multiple baffles 1011 instead of a stirring structure. This eliminates the need for an additional power source, and the structure is simple, easy to manufacture and install, and has low operating costs, making it easy to promote. Furthermore, the through holes 1012 on the baffles 1011 can enhance airflow disturbance, reduce radiation dead zones, and lower the risk of uneven lateral thermal field.

[0033] Specifically, such as Figure 1 As shown, the sintering chamber 101 of the roller kiln can be in a horizontal position for installation and use.

[0034] It should be noted that the shape of the through hole 1012 is not limited in the embodiments of this application. The through hole 1012 can be a regular hole or an irregular hole.

[0035] Furthermore, there is no limit to the number of through holes 1012; two, three, or more can be selected as needed. For example, such as Figure 4 As shown, the through hole 1012 can be a round hole, and multiple round holes are arranged in an array on the baffle 1011.

[0036] Or, such as Figure 5 As shown, the through hole 1012 can be a corrugated strip hole, and multiple corrugated strip holes are distributed at intervals along the height direction of the baffle 1011.

[0037] In one alternative implementation, such as Figure 2 and Figure 3 As shown, the kiln body 1 also includes a preheating chamber 102 located at the front end of the sintering chamber 101 and a cooling chamber 103 located at the rear end of the sintering chamber 101 along the material conveying direction.

[0038] The sintering chamber 101 is inclined upward relative to the cooling chamber 103.

[0039] And / or, the sintering chamber 101 is inclined downward relative to the preheating chamber 102.

[0040] In this embodiment, the sintering chamber 101 is inclined, meaning it is in an inclined position. When the material enters the sintering chamber 101, its own gravity, combined with the baffle 1011 and the conveying mechanism 2, allows the material to move relative to each other within the sintering chamber 101. This significantly enhances the momentum, heat, and mass transfer processes and the reaction process within the sintering chamber 101. Specifically, it strengthens the mixing process of the material within the kiln body 1, enhances the gas-solid and solid-solid mass transfer interfaces, and eliminates heat buildup. This significantly improves the uniformity of the temperature field, atmosphere field, and reaction field distribution within the sintering chamber 101, thereby achieving stable preparation of lithium iron phosphate cathode materials. The compaction requirements of lithium iron phosphate can be met in a single sintering.

[0041] Specifically, the material is transported unidirectionally within the roller kiln. In the embodiments of this application, "front" and "rear" directions refer to the front and rear ends of the material transport direction.

[0042] In one alternative implementation, such as Figure 3 As shown, the tilt angle of the sintering cavity 101 is θ, which satisfies 2°≤θ<90°.

[0043] Specifically, such as Figure 3 As shown, the tilt angle θ of the sintering cavity 101 refers to the acute angle formed by the length direction of the sintering cavity 101 and the length direction of the cooling cavity 103, or the acute angle formed by the length direction of the sintering cavity 101 and the length direction of the preheating cavity 102.

[0044] For example, in the embodiments of this application, the value of the tilt angle θ can be 2°, 15°, 30°, 45°, 80°, 89°, etc.

[0045] In one alternative implementation, 15° ≤ θ ≤ 80°.

[0046] In one alternative implementation, 5°≤θ≤30°.

[0047] In one alternative implementation, such as Figure 1 and Figure 2 As shown, the kiln body 1 also includes a feeding chamber 104 located at the front end of the preheating chamber 102 and a discharging chamber 105 located at the rear end of the cooling chamber 103 along the material conveying direction.

[0048] The feeding chamber 104 has a feeding port for receiving materials from the previous process or for directly adding materials. The materials enter the preheating chamber 102 from the feeding chamber 104 for preliminary preheating.

[0049] The preheating chamber 102 is used to preheat the material in preparation for high-temperature sintering. For example, it evaporates residual moisture in the material and decomposes and carbonizes organic binders.

[0050] The sintering chamber 101 is used to complete the production of grains and the formation of crystal forms. The sintering chamber 101 needs to maintain a temperature within a certain range and keep the temperature uniform so that the material undergoes a solid-state chemical reaction to generate crystals with a regular olivine structure. The sintering chamber 101 needs to be carried out in an inert or reducing atmosphere and needs to be isolated from oxygen. It should be noted that the structure for filling the sintering chamber 101 with gas can adopt existing structures, and this application embodiment does not impose too many restrictions on this.

[0051] For example, the sintering chamber 101 can employ four isothermal zones, sequentially designated as a first, second, third, and fourth isothermal zone along the material conveying direction. The first isothermal zone has a temperature range of 200°C to 380°C, where the material resides for approximately 1 hour. The second isothermal zone has a temperature range of 400°C to 580°C, where the material resides for approximately 2 hours. The third isothermal zone has a temperature range of 500°C to 680°C, where the material resides for approximately 2 hours. The fourth isothermal zone has a temperature range of 700°C to 900°C, where the material resides for approximately 10 hours.

[0052] The cooling chamber 103 is used to cool the reacted material from a high temperature to room temperature, thus achieving a shaping effect.

[0053] The discharge chamber 105 is used to smoothly deliver the cooled material out of the kiln body 1.

[0054] It should be noted that the structures of the feeding chamber 104, preheating chamber 102, cooling chamber 103 and discharging chamber 105 can all be any existing structure, and the specific settings can be selected according to actual needs.

[0055] In addition, the transmission mechanism 2 covers the feeding chamber 104, the preheating chamber 102, the cooling chamber 103, and the discharging chamber 105.

[0056] Furthermore, in an optional embodiment, the feeding chamber 104 and the preheating chamber 102 can be integrated into one unit, further simplifying the structure.

[0057] For example, the temperature range of the feeding chamber 104 and the preheating chamber 102 is from room temperature to 200°C. Room temperature is typically about 25°C. The temperature range of the sintering zone is from 100°C to 900°C. The cooling chamber 103 has a cooling rate of 1°C / min to 20°C / min, used to reduce the temperature of the material to room temperature.

[0058] In one alternative embodiment, the preheating chamber 102 and the cooling chamber 103 are horizontally distributed, which facilitates installation and material transportation.

[0059] In one alternative implementation, such as Figure 7As shown, there is a gap between the bottom of the baffle 1011 and the conveying mechanism 2. This gap is used for material to pass through and to prevent material from accumulating at the bottom of the baffle 1011.

[0060] Furthermore, in an alternative implementation, such as Figure 7 As shown, along the X direction, the gap length between the bottom of the baffle 1011 and the transmission mechanism 2 is L1, and the height dimension of the sintering cavity 101 along the X direction is L2, satisfying 0.1≤L1 / L2≤0.8.

[0061] By controlling L1 / L2 within a suitable range, a suitable material passage gap can be left between the baffle 1011 and the conveying mechanism 2, avoiding material accumulation at the bottom of the baffle 1011 and hindering internal heat transfer, which would lead to material heating imbalance and thus improve sintering quality.

[0062] Specifically, the X direction is as follows: Figure 3 As indicated by arrow X, which is the height direction of sintering cavity 101, the X direction is perpendicular to the bottom surface of sintering cavity 101.

[0063] For example, in the embodiments of this application, the value of L1 / L2 can be 0.1, 0.3, 0.45, 0.6, 0.7, 0.8, etc.

[0064] In one alternative implementation, 0.1 ≤ L1 / L2 ≤ 0.45.

[0065] It should be noted that the gap between the bottom of each baffle 1011 and the transmission mechanism 2 can be set to be the same as needed, or different gap sizes can be set as needed.

[0066] Furthermore, gaps may be left between the two sides of the baffle 1011 and the inner walls of the two sides of the sintering cavity 101.

[0067] In one alternative embodiment, the top of the baffle 1011 is fixed to the top wall of the sintering chamber 101. The material flows downwards due to its own gravity; placing the baffle 1011 on the top wall of the sintering chamber 101 facilitates material flow.

[0068] It should be noted that the fixing structure between the baffle 1011 and the sintering cavity 101 can be a snap-fit ​​fixing structure or a fastener fixing structure, and this application does not impose any restrictions on this. Compared with the snap-fit ​​fixing structure, the fastener fixing structure is more robust. In one possible implementation of this application, the baffle 1011 is fixed to the top wall of the sintering cavity 101 by bolts.

[0069] It should be noted that the embodiments of this application do not limit the structure of the transmission mechanism 2, as long as the transmission mechanism 2 can drive the material to pass through the feeding chamber 104, the preheating chamber 102, the sintering chamber 101, the cooling chamber 103 and the discharge chamber 105 in sequence.

[0070] In one alternative implementation, such as Figure 6 and Figure 7 As shown, the conveying mechanism 2 mainly includes a drive unit, multiple rollers 201, and a conveyor belt 202. The multiple rollers 201 are connected to the drive unit and are spaced apart at the bottom of the kiln body 1 along the material conveying direction. The conveyor belt 202 is fitted over the outside of the multiple rollers 201 and is used to place materials and move them along the material conveying direction. The conveying mechanism 2 uses a dense, non-porous conveyor belt 202 to transport materials, eliminating the need for traditional saggers and preventing material accumulation inside the saggers, ensuring uniform material flow and thus improving sintering quality. Furthermore, it simplifies the conveying structure and reduces operating costs, making it easier to promote.

[0071] Specifically, the driving component can be a drive motor, which drives multiple rollers 201 to rotate, and the multiple rollers 201 in turn drive the conveyor belt 202 to rotate, thereby realizing the transportation of materials. The materials are dynamically transported on the conveyor belt 202 in conjunction with the baffles 1011, and the through holes 1012 enhance airflow disturbance, which can reduce the risk of material thermal imbalance and uncontrolled micro-powder generation.

[0072] The following describes the roller kiln of the present application in further detail with reference to specific examples. These examples should not be construed as limiting the scope of protection claimed in this application.

[0073] Example 1: The material used is lithium iron phosphate spray material. The conveying mechanism 2 sequentially drives the material into the feeding chamber 104, preheating chamber 102, sintering chamber 101, cooling chamber 103, and discharging chamber 105. The preheating chamber 102 has a heating temperature of 90℃. The sintering chamber 101 has a first constant temperature zone with a heating temperature of 380℃, where the material stays for 1 hour; a second constant temperature zone with a heating temperature of 580℃, where the material stays for 2 hours; a third constant temperature zone with a heating temperature of 680℃, where the material stays for 2 hours; and a fourth constant temperature zone with a heating temperature range of 780℃, where the material stays for 10 hours. The cooling rate of the cooling chamber 103 is 20℃ / min.

[0074] The sintering cavity 101 has an inclination angle θ of 15°, an L1 / L2 ratio of 0.3, and a through hole 1012 is a round hole.

[0075] After the material is discharged from the discharge chamber 105, the compaction density and volume of five consecutive batches of material are tested, with the compaction density being 2.597 g / cm³. 32.611 g / cm 3 2.62 g / cm 3 2.631 g / cm 3 2.615 g / cm 3 The capacities are 146.2 mAh / g, 145.8 mAh / g, 145.4 mAh / g, 144.8 mAh / g, and 145.7 mAh / g, respectively.

[0076] Example 2: The material used is lithium iron phosphate spray material. The conveying mechanism 2 sequentially drives the material into the feeding chamber 104, preheating chamber 102, sintering chamber 101, cooling chamber 103, and discharging chamber 105. The preheating chamber 102 has a heating temperature of 90℃. The sintering chamber 101 has a first constant temperature zone with a heating temperature of 380℃, where the material stays for 1 hour; a second constant temperature zone with a heating temperature of 580℃, where the material stays for 2 hours; a third constant temperature zone with a heating temperature of 680℃, where the material stays for 2 hours; and a fourth constant temperature zone with a heating temperature range of 780℃, where the material stays for 10 hours. The cooling chamber 103 has a cooling rate of 20℃ / min.

[0077] The sintering cavity 101 has an inclination angle θ of 45°, an L1 / L2 ratio of 0.3, and a through hole 1012 is a round hole.

[0078] After the material is discharged from the discharge chamber 105, the compaction density and volume of five consecutive batches of material are tested, with the compaction density being 2.632 g / cm³. 3 2.625 g / cm 3 2.621 g / cm 3 2.633 g / cm 3 2.628 g / cm 3 The capacities are 144.6 mAh / g, 144 mAh / g, 145.6 mAh / g, 144.6 mAh / g, and 144.8 mAh / g, respectively.

[0079] Example 3: The material used is lithium iron phosphate spray material. The conveying mechanism 2 sequentially drives the material into the feeding chamber 104, preheating chamber 102, sintering chamber 101, cooling chamber 103, and discharging chamber 105. The preheating chamber 102 has a heating temperature of 90℃. The sintering chamber 101 has a first constant temperature zone with a heating temperature of 380℃, where the material stays for 1 hour; a second constant temperature zone with a heating temperature of 580℃, where the material stays for 2 hours; a third constant temperature zone with a heating temperature of 680℃, where the material stays for 2 hours; and a fourth constant temperature zone with a heating temperature range of 780℃, where the material stays for 10 hours. The cooling chamber 103 has a cooling rate of 20℃ / min.

[0080] The sintering cavity 101 has an inclination angle θ of 45°, an L1 / L2 ratio of 0.8, and a corrugated strip hole 1012.

[0081] After the material is discharged from the discharge chamber 105, the compaction density and volume of five consecutive batches of material are tested, with the compaction density being 2.643 g / cm³. 3 2.627 g / cm 3 2.626 g / cm 3 2.631 g / cm 3 2.63 g / cm 3 The capacities are 144.2 mAh / g, 145.3 mAh / g, 145.4 mAh / g, 144.8 mAh / g, and 144.7 mAh / g, respectively.

[0082] Comparative Example 1: The kiln employs a traditional roller kiln structure with eight feed saggers. The material used is lithium iron phosphate spray feed, and the sintering chamber 101 is kept horizontal without any tilt angle. The eight feed saggers sequentially pass through the feed chamber 104, preheating chamber 102, sintering chamber 101, cooling chamber 103, and discharge chamber 105. The preheating chamber 102 has a heating temperature of 90℃. The first isothermal zone of the sintering chamber 101 has a heating temperature of 380℃, where the material remains for 1 hour; the second isothermal zone has a heating temperature of 580℃, where the material remains for 2 hours; the third isothermal zone has a heating temperature of 680℃, where the material remains for 2 hours; and the fourth isothermal zone has a heating temperature of 780℃, where the material remains for 10 hours. The cooling rate of the cooling chamber 103 is 20℃ / min.

[0083] After the material is discharged from the discharge chamber 105, the compaction density and volume of the material in the 8 feed saggers are tested twice.

[0084] The compaction density measured in the first test was 2.553 g / cm³. 3 2.593 g / cm 32.532 g / cm 3 2.561 g / cm 3 2.514 g / cm 3 2.523 g / cm 3 2.582 g / cm 3 2.563 g / cm 3 The capacities are 144.3 mAh / g, 142.7 mAh / g, 145.6 mAh / g, 143.2 mAh / g, 144.3 mAh / g, 142.5 mAh / g, 143.8 mAh / g, and 144.1 mAh / g, respectively.

[0085] The compaction density measured in the second test was 2.561 g / cm³. 3 2.601 g / cm 3 2.543 g / cm 3 2.559 g / cm 3 2.521 g / cm 3 2.519 g / cm 3 2.577 g / cm 3 2.563 g / cm 3 The capacities are 143.6 mAh / g, 140.2 mAh / g, 144.1 mAh / g, 143.3 mAh / g, 143.8 mAh / g, 144.6 mAh / g, 142.9 mAh / g, and 144.1 mAh / g, respectively.

[0086] It should be noted that all embodiments and comparative examples in this application use the same lithium iron phosphate spray material.

[0087] Based on the compaction density and capacity test results of Examples 1, 2, and 3 and Comparative Example 1, it can be seen that the compaction density and compaction capacity of the lithium iron phosphate cathode material prepared in this application are improved. Furthermore, the compaction density and capacity of each batch in this application are consistent, with minimal fluctuations, and the consistency pass rate is significantly improved.

[0088] In this embodiment, the compaction density was tested using a Sansi Test UTM7305. After the coin cells were prepared, the capacity was tested using a Newway tester with a constant discharge power method. The test conditions were: voltage range of 2.0 V to 3.75 V, charge of 0.1 C, and temperature of 25 °C.

[0089] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A roller kiln, characterized in that, include: The kiln body (1) includes a sintering chamber (101), and multiple baffles (1011) are spaced apart in the sintering chamber (101) along the material conveying direction. Multiple through holes (1012) are spaced apart on the baffles (1011). The conveying mechanism (2) is located at the bottom of the kiln body (1) and is used to drive the material to move along the conveying direction.

2. The roller kiln according to claim 1, characterized in that, The kiln body (1) also includes a preheating chamber (102) located at the front end of the sintering chamber (101) and a cooling chamber (103) located at the rear end of the sintering chamber (101) along the material conveying direction. The sintering chamber (101) is inclined upward relative to the cooling chamber (103); And / or, the sintering chamber (101) is inclined downward relative to the preheating chamber (102).

3. The roller kiln according to claim 2, characterized in that, The tilt angle of the sintering cavity (101) is θ, which satisfies 2°≤θ<90°.

4. The roller kiln according to claim 3, characterized in that, 15°≤θ≤80°; Alternatively, 5°≤θ≤30°.

5. The roller kiln according to claim 2, characterized in that, The kiln body (1) also includes a feeding chamber (104) located at the front end of the preheating chamber (102) and a discharging chamber (105) located at the rear end of the cooling chamber (103) along the material conveying direction. And / or, the preheating chamber (102) and the cooling chamber (103) are horizontally distributed.

6. The roller kiln according to any one of claims 1 to 5, characterized in that, There is a gap between the bottom of the baffle (1011) and the transmission mechanism (2).

7. The roller kiln according to claim 6, characterized in that, Along the X direction, the gap length between the bottom of the baffle (1011) and the transmission mechanism (2) is L1, and the height dimension of the sintering cavity (101) along the X direction is L2, satisfying 0.1≤L1 / L2≤0.

8.

8. The roller kiln according to claim 7, characterized in that, 0.1≤L1 / L2≤0.

45.

9. The roller kiln according to claim 8, characterized in that, The top of the baffle (1011) is fixed to the top wall of the sintering cavity (101); And / or, the through hole (1012) includes a regular hole or an irregular hole, the regular hole including a round hole or a corrugated strip hole.

10. The roller kiln according to any one of claims 1 to 5, characterized in that, The transmission mechanism (2) includes: Drive components; Multiple rollers (201) are connected to the drive unit, and the multiple rollers (201) are spaced apart at the bottom of the kiln body (1) along the material conveying direction; A conveyor belt (202) is fitted over the outside of the plurality of rollers (201) for placing materials and moving the materials along the conveying direction.

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