Air inlet structure and roller kiln

Abstract

The invention belongs to the technical field of lithium battery manufacturing, and relates to a gas inlet structure of a roller kiln for fuel gas sintering of a lithium battery positive electrode material and the roller kiln. An air inlet structure comprises a hollow structure defined by a heat preservation material. A plurality of groups of fins are arranged in the hollow structure and are arranged along the width direction of the furnace wall; the multiple sets of fins comprise first fins and second fins, and the first fins and the second fins are arranged in a staggered mode to form a serpentine channel. The hollow structure is divided into a first cavity structure, a fin area and a second cavity structure by a plurality of groups of fins; the thermal insulation material above the hollow structure is provided with a first diversion port communicated with the hollow structure, and the thermal insulation material below the hollow structure is provided with a second diversion port; and oxygen sequentially passes through the second flow dividing opening, the fin area and the first flow dividing opening to enter the furnace. According to the roller kiln, the fins of specific structures and the shunting device are arranged at the bottom, so that the uniformity of a temperature field in the roller kiln is remarkably improved, and the consistency of the material sintering degree is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery manufacturing, and relates to an air inlet structure and a roller hearth kiln for a roller hearth kiln for gas sintering lithium battery cathode materials. Background Art

[0002] As an indispensable heat treatment device in the production process of lithium battery cathode materials, the roller hearth kiln includes: a furnace body, a heating device, a conveying device, and an atmosphere regulating device; wherein, the furnace body is sequentially provided with a plurality of temperature zones along the conveying direction; the conveying device passes through the interior of the furnace cavity of the furnace body and is used for conveying the material to be sintered through the temperature zones; the atmosphere regulating device is used for regulating the sintering atmosphere inside the furnace cavity of the furnace body; the conveying device includes a plurality of crucibles for carrying the material to be sintered. One or more air inlet structures are respectively arranged on the lower wall and the side wall of the furnace body. The design rationality and performance of the air inlet structure directly affect the uniformity of the temperature field in the furnace and the quality of the final product. In various industrial fields involving heat exchange and precise temperature control, the performance requirements for related equipment are becoming increasingly stringent, especially in the lithium battery cathode material production industry. Currently, most of the air inlet structures of the roller hearth kiln for lithium battery cathode material production still adopt the traditional method of directly introducing gas into the kiln through the side and bottom air inlet diameters. This conventional air inlet method gradually exposes a series of serious problems in actual production operations. For example, since the inlet air is not sufficiently preheated or effectively guided, the temperature difference between it and the high-temperature environment in the kiln is extremely large, which will generate a strong cooling impact on the area near the air inlet. This results in a serious uneven distribution of the temperature field in the furnace. For example, in many actual production scenarios, the temperature in the area near the air inlet may be more than 20°C lower than the ideal working temperature in the kiln. This significant temperature difference causes the cathode material to be heated unevenly during sintering, and the sintering effects of the materials at different positions are uneven, which seriously affects the consistency of the product quality. In the subsequent manufacturing and use links of lithium batteries, the inconsistency of product quality may lead to the discretization of battery performance, such as large fluctuations in indicators such as battery capacity, charge and discharge efficiency, and cycle life, greatly reducing the safety and stability of lithium batteries.

[0003] Furthermore, from the perspective of energy efficiency, the uneven temperature field caused by the traditional air intake structure forces some areas in the kiln to increase the power of the heating element or extend the heating time in order to maintain a suitable sintering temperature, which undoubtedly causes excessive waste of energy. In addition, the traditional roller kiln air intake structure also has many inconveniences in maintenance and cleaning. The simple air inlet design can easily cause impurities, dust, etc. to flow into the kiln along with the air intake, and gradually accumulate in the air intake channel. Over time, these deposits will interfere with the normal circulation of gas, causing unstable air intake and further destroying the stability of the temperature field in the furnace. Cleaning these deposits often requires professionals to spend a lot of time and energy, and even requires partial disassembly of the equipment, which not only increases maintenance costs, but also prolongs equipment downtime and reduces the overall utilization of the equipment.

[0004] At present, the existing technology has carried out some exploration and research on the optimization of the air intake structure of the roller kiln, and has achieved some results. For example, the existing technology CN202320465430.5 discloses a roller kiln and its air intake device. By adding a shielding cap to the air intake branch pipe, the position of the air outlet of the air intake branch pipe is changed, which alleviates the problem of fine impurities blocking the air outlet to a certain extent. However, this solution mainly focuses on preventing impurities from clogging, and does not effectively solve the core problem of low heat exchange efficiency between the air intake and the high temperature environment in the kiln, which leads to uneven temperature field.

[0005] For another example, the prior art CN202310232769.5 discloses a roller kiln with side preheating air intake, which supplies oxygen to the front section of the kiln body with the help of a gas pipeline mechanism, thus meeting the oxygen demand of the material in the front section of the kiln body. However, this solution still has room for improvement in terms of improving heat exchange efficiency and optimizing the uniformity of the overall temperature field in the furnace, and cannot fully meet the stringent requirements of high-quality production of lithium battery positive electrode materials for temperature field uniformity. Summary of the invention

[0006] The object of the present invention is to provide an air intake structure and a roller kiln which can solve the problem of uneven temperature field in a furnace and improve the air intake heat exchange efficiency.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] An air intake structure comprises a hollow structure surrounded by a heat-insulating material; a plurality of groups of fins are arranged in the hollow structure, and the plurality of groups of fins are arranged along the width direction of a furnace wall; the plurality of groups of fins comprise a first fin and a second fin, and the first fin and the second fin are arranged alternately to form a serpentine channel; the hollow structure is divided into a first cavity structure, a fin area, and a second cavity structure by the plurality of groups of fins;

[0009] The heat insulation material above the hollow structure is provided with a first diversion port communicating with the hollow structure, and the heat insulation material below the hollow structure is provided with a second diversion port; oxygen enters the furnace successively through the second diversion port, the fin area, and the first diversion port.

[0010] The first cavity structure is used to guide the gas coming out of the second diversion port to accurately flow to the fin area, and the second cavity structure is used to guide the gas coming out of the fin area to flow to the first diversion port, so as to enter the furnace.

[0011] The first fins and the second fins are arranged staggeredly to form a serpentine channel, so that the gas passes through the serpentine channel in the fin area, keeping the temperature of the gas in the intake structure with a small temperature difference and improving the temperature uniformity.

[0012] In one preferred embodiment, there are multiple first diversion ports, arranged in rows along the gas flow direction.

[0013] In one preferred embodiment, the first diversion ports are arranged in 1 - 4 rows, and each row has 3 - 12 first diversion holes.

[0014] In one preferred embodiment, the arrangement of the first diversion ports is three rows, and each row has 4 first diversion holes.

[0015] In one preferred embodiment, the heat insulation material above the hollow structure is a first heat insulation brick, and the heat insulation material below the hollow structure is a second heat insulation brick. The first heat insulation brick is provided with a concave structure. The fins are located in the concave structure.

[0016] In one preferred embodiment, the first fins are fixed to the side wall of the first heat insulation brick close to the furnace interior; the second fins are fixed to the side wall of the first heat insulation brick close to the furnace exterior.

[0017] In one preferred embodiment, the heat insulation material above the hollow structure is a first heat insulation brick, and the heat insulation material below the hollow structure is a second heat insulation brick. The joint surfaces of the first heat insulation brick and the second heat insulation brick are both provided with recessed areas, and the two recessed areas are opposite in position and the same in size; the fins are located in the concave structure.

[0018] In one preferred embodiment, the first fins are fixed to the side wall of the heat insulation material close to the furnace interior; the second fins are fixed to the side wall of the heat insulation material close to the furnace exterior.

[0019] In one preferred embodiment, the heat insulation material above the hollow structure is a first heat insulation brick, and the heat insulation material below the hollow structure is a second heat insulation brick. The second heat insulation brick is provided with a concave structure. The fins are located in the concave structure.

[0020] In one preferred embodiment, the thermal insulation material above the hollow structure is the first thermal insulation brick, and the thermal insulation material below the hollow structure is the second thermal insulation brick. A concave structure is provided in the second thermal insulation brick, and the fin is located in the concave structure. The first thermal insulation brick is in an inverted U-shaped structure, and the second thermal insulation brick is arranged in the U-shaped structure.

[0021] In one preferred embodiment, the first fin is fixed to the side wall of the second thermal insulation brick close to the inside of the furnace; the second fin is fixed to the side wall of the second thermal insulation brick close to the outside of the furnace.

[0022] In one preferred embodiment, the upper parts of multiple groups of fins are fixedly connected to the bottom of the first thermal insulation brick.

[0023] In one preferred embodiment, the thicknesses of the first thermal insulation brick and the second thermal insulation brick are 100 - 150 mm.

[0024] In one preferred embodiment, the fin height is 10 - 20 mm.

[0025] When the fin height is designed within this range, it can effectively conduct heat exchange with the intake air while avoiding interfering with the material transportation.

[0026] In one preferred embodiment, the fin forms an angle of 15 - 90 degrees with the top surface of the second thermal insulation brick.

[0027] In one preferred embodiment, the fin forms an angle of 30 - 50 degrees with the top surface of the second thermal insulation brick, for example, 40 degrees.

[0028] In one preferred embodiment, the spacing between adjacent fins is 3 - 15 mm, preferably 3 - 7 mm; more preferably 4 - 6 mm, for example, 5 mm.

[0029] If the spacing between adjacent fins is too large or too small, the preheating effect will be reduced.

[0030] In one preferred embodiment, the material of the fin is the same as that of the thermal insulation material, and its thermal conductivity is 0.10 - 0.30 W / (m·K), having good thermal stability in a high-temperature environment.

[0031] In one preferred embodiment, the material of the fin is a high-temperature resistant ceramic fiber material.

[0032] In one preferred embodiment, the thickness of the fin is 0.5 - 1.5 cm.

[0033] In one preferred embodiment, an intake channel is provided in the second thermal insulation brick. The intake channel is located below the hollow structure; the intake channel communicates with the intake port and the second shunt port; oxygen enters the hollow structure through the intake port, the intake channel, and the second shunt port in sequence.

[0034] In one preferred embodiment, the intake passage located in the hollow structure section is provided with a plurality of gas outlets corresponding to a plurality of second shunt openings.

[0035] In one preferred embodiment, the number of the second shunt openings is 2 - 5.

[0036] Too many or too few numbers of the second shunt openings will affect the preheating effect.

[0037] The size and distribution of the shunt holes are designed according to the intake flow rate and the size of the intake port to ensure uniform distribution of the intake flow rate.

[0038] After the intake air is preheated by the fins and evenly distributed by the shunt device (intake passage, first shunt opening and second shunt opening), when it enters the kiln, the temperature is closer to the main body temperature in the kiln, reducing the cooling effect of the intake air on the local area, making the temperature distribution in the kiln more uniform, and effectively improving the consistency of the material sintering degree.

[0039] Based on the same inventive concept, the present invention also claims to protect a roller hearth kiln including the intake structure.

[0040] In one preferred embodiment, the roller hearth kiln is used for gas sintering of the cathode material of lithium batteries.

[0041] In one preferred embodiment, the intake structure is arranged at the bottom of the furnace of the constant temperature section of the roller hearth kiln.

[0042] In one preferred embodiment, the intake port is arranged on the furnace wall of the constant temperature section.

[0043] In one preferred embodiment, there are a plurality of the intake structures and they are located in the same plane.

[0044] In one preferred embodiment, the intake structure is arranged at a position 10 - 50 mm above the bottom surface of the roller hearth kiln.

[0045] In one preferred embodiment, the diameter of the intake passage of the intake structure is 20 - 25 mm.

[0046] The beneficial effects of the present invention are as follows:

[0047] 1. By setting fins with a specific structure and a flow splitting device at the bottom, the present invention significantly improves the uniformity of the temperature field in the roller hearth kiln. The experimental results show that after the intake air is preheated by the fins and evenly distributed by the flow splitting device, the temperature when entering the kiln is closer to the main body temperature in the kiln, reducing the cooling effect of the intake air on local areas and making the temperature distribution in the kiln more uniform. For example, during the process, the temperature difference between the area near the intake port and the central area in the kiln before improvement could reach 20 °C, and after improvement, it is reduced to 12.8 °C, providing a stable and uniform sintering temperature environment for the lithium battery cathode material and effectively improving the consistency of the material sintering degree.

[0048] 2. The improvement of the temperature field uniformity will significantly improve the quality of the lithium battery cathode material produced. The experimental results show that the sintering degree of each position of the material is similar, effectively avoiding overburning or underburning, and the performance indicators are more stable. Taking the 18650-type lithium battery cathode material as an example, the deviation of the product capacity consistency before improvement was about 8.7%, and after improvement, it can be reduced to 4.8%, thus improving the overall quality and stability of the lithium battery products and enhancing the market competitiveness.

[0049] 3. The optimized intake air structure makes the temperature distribution in the furnace more reasonable. The experimental results show that it can reduce the additional energy consumption of some areas in the kiln caused by the uneven temperature field. Under the same output, the energy consumption of the improved roller hearth kiln can be reduced by 8.67% compared with that before improvement, effectively reducing the production cost and meeting the development trend of energy conservation and emission reduction.

[0050] 4. The fins are made of the same material as the thermal insulation material of the roller hearth kiln and have a simple shape, the same material as the insulating brick, avoiding problems such as inconvenient installation and different thermal expansion caused by material differences. The simplified shape reduces the maintenance difficulty. The maintenance process shows that the staff can disassemble and replace the damaged fins more quickly, reducing the equipment downtime for maintenance and improving the equipment operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is an overall view of the roller hearth kiln for sintering lithium battery cathode material with gas;

[0052] Figure 2 It is a front view of a single-section furnace kiln in the constant temperature section;

[0053] Figure 3 It is a side view of a single-section furnace kiln in the constant temperature section;

[0054] Figure 4 It is a sectional view of a single-section furnace kiln in the constant temperature section;

[0055] Figure 5 It is an axonometric view of the intake air structure;

[0056] Figure 6 It is a top view of the intake air structure;

[0057] Figure 7 Axonometric view of the second heat-insulating brick of the intake structure;

[0058] Figure 8 Top view of the second heat-insulating brick of the intake structure;

[0059] Figure 9 Cross-sectional view of the intake structure;

[0060] Figure 10 Contour map of the fluid region temperature distribution of the intake structure of the present invention;

[0061] Figure 11 Contour map of the fluid region temperature distribution of the intake structure without fins;

[0062] In the figure, 1 is the ceramic protective sleeve outside the upper heating rod, 2 is the sagger, 3 is the roller path, 4 is the lower heating rod, 5 is the first diversion port; 6 is the intake hole; 7 is the fin; 8 is the hollow structure; 9 is the first heat-insulating brick; 10 is the second heat-insulating brick, 11 is the second diversion port; 12 is the intake structure, 13 is the first cavity structure, 14 is the second cavity structure, 15 is the intake passage. Specific embodiments

[0063] The present invention is not limited to the following specific embodiments. Those of ordinary skill in the art can implement the present invention in other various specific embodiments according to the content disclosed in the present invention, or those that adopt the design structure and idea of the present invention and make simple changes or modifications all fall within the protection scope of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0064] Embodiment 1

[0065] As Figures 1 to 3 shown, the roller hearth kiln for the gas-sintered lithium battery cathode material of the present invention includes a heating section, a constant temperature section, and a cooling section arranged in sequence. The intake structure of the present invention is arranged in the constant temperature section.

[0066] In the kiln furnace of the constant temperature section, the sagger 2 moves on top of the roller rod 3, and products are placed in the sagger 2. A protective sleeve 1 is arranged above the sagger 2, and a heating rod 4 is arranged below the roller rod 3. In this embodiment, one layer of sagger 2 is placed in the roller hearth kiln, and intake structures 12 are provided on both side walls of the kiln furnace in the constant temperature section. Oxygen is introduced into the intake structure 12. Among them, two intake structures are provided at the bottom of the kiln furnace in the constant temperature section, and are arranged at a position 10 - 50 mm above the bottom surface of the roller hearth kiln; in this way, sufficient oxygen can be ensured in the sagger 2 for the reaction.

[0067] The two intake structures 12 are located in the same plane.

[0068] The structural diagram of the air intake structure is as shown in Figures 4 - 9 Figure 1. The air intake structure 12 of the present invention includes a hollow structure 8 surrounded by heat-insulating materials; a plurality of groups of fins are arranged in the hollow structure 8, and the plurality of groups of fins are arranged along the width direction of the furnace wall; the plurality of groups of fins include a first fin and a second fin, and the first fin and the second fin are arranged in an alternating manner to form a serpentine channel; the hollow structure 8 is divided into a first cavity structure 13, a fin area, and a second cavity structure 14 by the plurality of groups of fins;

[0069] The heat-insulating material above the hollow structure is provided with a first shunt port 5 communicating with the hollow structure, and the heat-insulating material below the hollow structure is provided with a second shunt port 11; oxygen enters the furnace through the second shunt port 11, the fin area, and the first shunt port 5 in sequence.

[0070] The arrangement direction of the first shunt port 5 is: in a row shape along the air flow direction. In this embodiment, it is one row of 12 columns.

[0071] The first cavity structure 13 is used to guide the gas coming out of the second shunt port 11 to accurately flow to the fin area, and the second cavity structure 14 is used to guide the gas coming out of the fin area to flow to the first shunt port 5, so as to enter the furnace.

[0072] An air intake channel 15 is provided in the second heat-insulating brick 10, and the air intake channel 15 is located below the hollow structure 8; the air intake channel communicates with the air intake port 6 and the second shunt port 11; oxygen enters the hollow structure 8 through the air intake port 6, the air intake channel 15, and the second shunt port 11 in sequence.

[0073] The diameter of the air intake channel 15 of the air intake structure 12 is 20 - 25 mm.

[0074] The heat-insulating material above the hollow structure is a first heat-insulating brick 9, and the heat-insulating material below the hollow structure is a second heat-insulating brick 10. The second heat-insulating brick 10 is provided with a concave structure. The fin 7 is located in the concave structure. The first heat-insulating brick 9 is in an inverted U-shaped structure, and the second heat-insulating brick 10 is arranged in the U-shaped structure.

[0075] The first fin is fixed to the side wall of the second heat-insulating brick 10 close to the furnace interior; the second fin is fixed to the side wall of the second heat-insulating brick 10 close to the furnace exterior.

[0076] The top of the fin 7 is fixedly connected to the bottom of the first heat-insulating brick 9. The height of the fin 7 is 10 - 20 mm. The thickness of both heat-insulating bricks is 132 mm.

[0077] The height of the fin 7 is designed within this range, which can avoid interfering with the material transportation while effectively exchanging heat with the intake air.

[0078] The fin 7 forms an angle of 15 - 90 degrees with the top surface of the second heat-insulating brick 10. Figure 4The situation shown is 90 degrees.

[0079] The spacing between adjacent fins is 5 mm. The material of fin 7 is the same as that of the insulating brick, and its thermal conductivity is 0.10 - 0.30 W / (m·K), having good thermal stability in high-temperature environments.

[0080] The intake channel is provided with 2 outlets, corresponding to 2 second shunt ports. The number of second shunt ports is 2.

[0081] The preparation of the intake structure of the roller hearth kiln includes the following steps:

[0082] (1) Installation of intake port fins: First, prepare the materials. Select a high-temperature resistant ceramic fiber material that is the same as the insulating material of the roller hearth kiln. This material has good stability in high-temperature environments and a low thermal conductivity of up to 0.1 W / (m·K), effectively meeting the heat insulation and heat exchange requirements of the intake structure. Then, use a high-precision cutting device to cut the ceramic fiber material into fins. When cutting, strictly control the dimensional accuracy so that the inclination angle of the fins is accurately set at 45 degrees, with an allowable error of ±0.5 degrees; the spacing between adjacent fins is 5 mm, with an error of ±0.2 mm. After cutting, carefully clean the inner wall of the intake port to remove impurities and dust. Subsequently, evenly apply a high-temperature resistant adhesive to the bonding surface between the fins and the inner wall of the insulating brick, and paste the fins according to the designed angle and spacing. To ensure firm bonding, use an auxiliary fixing fixture to temporarily fix it, and remove the fixture after the adhesive is fully cured. At the same time, install high-temperature resistant buckles at the connection part as a removable auxiliary fixing structure for later maintenance and replacement.

[0083] The fins are processed into a flat shape with a width of 1 cm. They are installed on the surface of the intake port in an array form. First, mark the installation positions on the surface of the intake port to ensure that the horizontal spacing between adjacent fins is 5 mm, and the error range is controlled within ±0.2 mm. After marking, paste the fins with a high-temperature resistant adhesive and use an auxiliary fixing fixture to ensure the installation accuracy.

[0084] Set the kiln body to the property of a high-temperature resistant ceramic material, the fins and the insulating material to the property of the same ceramic fiber material, and the intake gas to the property of the actual production gas. After installing the intake structure of the roller hearth kiln into the furnace wall of the constant temperature section, set the gas temperature and speed at the intake port to 30°C and 5 m / s respectively, and set the outlet gauge pressure to atmospheric pressure. Then carry out the preparation of the cathode material.

[0085] Statistically analyze the results such as the temperature field distribution, intake flow, and heat exchange efficiency.

[0086] The temperature distribution contour map of the fluid region of the intake structure of the present invention is as Figure 10As shown. Correspondingly, for the traditional air intake structure, referring to the prior art CN201920469652.8 (a manufacturing method of the bottom air intake structure of a roller hearth kiln), that is, the fluid region temperature distribution contour map of the air intake structure without fins is as Figure 11 shown.

[0087] Example 2

[0088] Optimization of the fin inclination angle

[0089] The angles between the fins 7 and the top surface of the second insulating brick 10 are respectively set to 15°, 30°, 40°, 45°, 50°, 60°, and 70°. Keeping other parameters unchanged, it is the same as Example 1.

[0090] The lithium - battery cathode material precursor is placed in the sagger, and the sagger moves forward along the roller hearth. During the movement, sintering reactions occur, mainly including two types: dehydration and decomposition of the precursor, and solid - phase reaction.

[0091] Through the air intake and heating links in the production process of the lithium - battery cathode material, the temperature field in the kiln is analyzed, with a focus on the temperature difference between the area near the air intake and the central area in the kiln.

[0092] The results show that when the inclination angle is 45°, the temperature difference between the air intake area and the central area in the kiln is the smallest, which is 11.4 °C, and the temperature field uniformity is the best; when the inclination angles are 15°, 30°, 40°, 50°, 60°, and 70° respectively, the temperature differences are 12.8 °C, 12.4 °C, 12.1 °C, 12.5 °C, 13.1 °C, and 14 °C respectively. This indicates that this inclination angle can fully pre - heat the air intake between the fins and evenly disperse it into the kiln, effectively reducing the cooling effect of the air intake on the side area, and thus improving the uniformity of the temperature field. Considering the uniformity, the preferred inclination angle is 30 - 50°, and more preferably 45°.

[0093] Example 3

[0094] Optimization of the fin spacing

[0095] Keeping other parameters unchanged, the spacings between adjacent fins are respectively set to 3 mm, 4 mm, 5 mm, and 7 mm. Through the air intake and heating links in the production process of the lithium - battery cathode material, the flow situation of the air intake in the bottom fin area is observed, and the temperature distribution at the bottom of the kiln is analyzed. The experimental data shows that when the horizontal fin spacing is 5 mm, the air intake flows most uniformly in the bottom fin area, the temperature difference is 12.1 °C, and it can fully exchange heat with the fins, making the temperature distribution at the bottom of the kiln more uniform; at other spacings, the above - mentioned temperature difference increases. For example, when the horizontal fin spacings are 3 mm and 7 mm respectively, the temperature differences are 12.7 °C and 12.8 °C respectively. Unreasonable fin spacings will have an adverse impact on the temperature field uniformity.

[0096] Example 4

[0097] Optimization of the size and distribution of the shunt holes

[0098] Change the size and distribution of the first shunt holes on the shunt plate. Through the air intake and heating links in the production process of the lithium battery cathode material, observe the uniformity of the air intake flow distribution at each shunt port and the change in the uniformity of the overall temperature field in the kiln. The experimental results show that when the size and distribution of the first shunt holes on the shunt plate are precisely designed according to the air intake flow and the air intake port size, and the diversion grooves can effectively guide the gas flow to the fin area, the air intake flow distribution is uniform, and the uniformity of the temperature field in the kiln is significantly improved.

[0099] The area design formula for the shunt holes is as follows:

[0100]

[0101] Where A i is the area of a single shunt hole, and A inlet is the desired flow rate of a single shunt hole.

[0102] Specifically, for different sizes and distributions of the first shunt holes, the temperature uniformity index is shown in Table 1.

[0103] Table 1 Influence of different sizes and distributions of the first shunt holes on the temperature uniformity relationship

[0104]

[0105] As can be seen from Table 1, the diameter and distribution form of the first shunt holes have a certain influence on the temperature uniformity index. The larger the diameter of the first shunt hole and the more concentrated the distribution, the better the temperature uniformity index.

[0106] Example 5

[0107] With the optimized parameters, that is, the diameter of the first shunt hole is 12 mm, the distribution form is 3×4, that is, three rows and four columns, the lateral spacing of the fins is 5 mm, and the angle between the fin 7 and the top surface of the second insulating brick 10 is 45 degrees, and the other parameters refer to Example 1, the cathode material is prepared.

[0108] Assemble the cathode material into a battery, and the assembly steps are as follows:

[0109] 1. Preparation of the electrode sheet: Mix the sintered cathode material with an appropriate amount of binder and conductive agent, add a solvent and stir into a uniform slurry. Then coat the slurry on the aluminum foil current collector and make the positive electrode sheet through processes such as drying and rolling. The binder and conductive agent are commonly used, for example, the binder is polyvinylidene fluoride and the conductive agent is graphite.

[0110] 2. Negative electrode preparation: The commonly used negative electrode material for 18650 lithium batteries is graphite. Similarly, graphite is mixed with a binder, a conductive agent, etc. to form a slurry, which is then coated on a copper foil current collector to form a negative electrode sheet.

[0111] 3. Diaphragm installation: The diaphragm is usually a polymer film with a microporous structure, such as polypropylene (PP) or polyethylene (PE) diaphragm. The diaphragm is placed between the positive and negative electrodes to isolate the positive and negative electrodes and prevent short circuits, while allowing lithium ions to pass through.

[0112] 4. Winding or lamination: The positive electrode sheet, separator, and negative electrode sheet are stacked in order, and then formed into a battery core by winding or lamination. The winding method is to roll the three layers of materials into a cylindrical shape, and the lamination method is to stack them layer by layer.

[0113] 4. Install into the shell: Place the battery core into the stainless steel or aluminum shell of the 18650 battery.

[0114] The negative electrode of the battery is made of graphite material. Through voltage testing, charge and discharge testing, internal resistance testing, and safety performance testing, the results show that the performance of the optimized positive electrode material has improved by an average of 5.75%.

[0115] The experimental results show that the sintering degree of each position of the material is similar, and various performance indicators are more stable. Before the improvement of the 18650 lithium battery positive electrode material (i.e. the existing technology CN201920469652.8), the product capacity consistency deviation was about 8.7%, which can be reduced to 4.8% after the improvement, thereby improving the overall quality and stability of lithium battery products and enhancing market competitiveness.

[0116] By monitoring the outer wall temperature of the roller kiln through infrared thermal imaging, it was found that the outer wall temperature was lower after the improvement. The energy consumption for seven days was calculated and statistically analyzed based on the principle of heat transfer. The results showed that under the same output, the energy consumption of the improved roller kiln can be reduced by 8.67% compared with that before the improvement, effectively reducing production costs.

[0117] It should be noted that the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the embodiments here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. An intake structure, characterized in that, It includes a hollow structure surrounded by heat-insulating materials; multiple groups of fins are arranged inside the hollow structure, and the multiple groups of fins are arranged along the width direction of the furnace wall; the multiple groups of fins include first fins and second fins, and the first fins and the second fins are arranged in an alternating manner to form a serpentine channel; the hollow structure is divided into a first cavity structure, a fin area, and a second cavity structure by the multiple groups of fins; The heat-insulating material above the hollow structure is provided with a first diversion port communicating with the hollow structure, and the heat-insulating material below the hollow structure is provided with a second diversion port; oxygen enters the furnace in sequence through the second diversion port, the fin area, and the first diversion port.

2. The intake structure according to claim 1, wherein, The heat-insulating material above the hollow structure is a first heat-insulating brick, and the heat-insulating material below the hollow structure is a second heat-insulating brick. The first heat-insulating brick is internally provided with a concave structure; the fins are located inside the concave structure; the first fins are fixed to the side wall of the first heat-insulating brick close to the furnace interior; the second fins are fixed to the side wall of the first heat-insulating brick close to the furnace exterior.

3. The intake structure according to claim 1, characterized in that, The heat-insulating material above the hollow structure is a first heat-insulating brick, and the heat-insulating material below the hollow structure is a second heat-insulating brick. The joint surfaces of the first heat-insulating brick and the second heat-insulating brick are both provided with concave areas, and the two concave areas are opposite in position and the same in size.

4. The intake structure according to claim 1, characterized in that, The heat-insulating material above the hollow structure is a first heat-insulating brick, and the heat-insulating material below the hollow structure is a second heat-insulating brick. The second heat-insulating brick is internally provided with a concave structure, and the first heat-insulating brick is in an inverted U-shaped structure. The second heat-insulating brick is arranged inside the U-shaped structure; the first fins are fixed to the side wall of the second heat-insulating brick close to the furnace interior; the second fins are fixed to the side wall of the second heat-insulating brick close to the furnace exterior.

5. The intake structure according to claim 1, wherein, The upper parts of the multiple groups of fins are fixedly connected to the bottom of the first heat-insulating brick; the distance between adjacent fins is 3-15 mm.

6. The intake structure according to claim 1, wherein The fins form an angle of 15-90 degrees with the top surface of the second heat-insulating brick; preferably 30-50 degrees.

7. The intake structure according to any one of claims 1-6, characterized in that, The second heat-insulating brick is internally provided with an air inlet channel, and the air inlet channel is located below the hollow structure; the air inlet channel communicates with the air inlet and the second diversion port; Oxygen enters the hollow structure in sequence through the air inlet, the air inlet channel, and the second diversion port.

8. A roller hearth kiln, characterized in that, It includes the air inlet structure according to any one of claims 1-7. Preferably, the roller hearth kiln is used for gas sintering of lithium battery cathode materials.

9. The roller hearth kiln according to claim 8, characterized in that, The air inlet structure is arranged at the bottom of the kiln furnace in the constant temperature section of the roller hearth kiln; the air inlet is arranged on the furnace wall in the constant temperature section.

10. The roller hearth kiln according to claim 8, characterized in that, There are multiple air inlet structures, and they are located in the same plane; the air inlet structures are arranged at a position 10-50 mm above the bottom surface of the roller hearth kiln.

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