A zoned gas-supply roller kiln for calcining NCM811 materials and its control method

Abstract

This invention provides a zoned gas-supply roller kiln and its control method for calcining NCM811 materials, belonging to the field of lithium battery cathode material preparation technology. It includes rollers horizontally penetrating a low-temperature zone, a transition zone, and a high-temperature zone, with the top surface of the rollers supporting a sagger. Upper and lower partition walls correspondingly enclose the kiln chamber, with radiant tubes located within it. The low-temperature zone has an air inlet and an exhaust outlet, while the high-temperature zone has a mixing inlet. An atmosphere isolation structure separates the low-temperature and high-temperature zones. The air inlet communicates only with the low-temperature zone kiln chamber, while the mixing inlet communicates with the high-temperature zone kiln chamber, and the mixing inlet is equipped with a gas mixing device. This invention, employing the aforementioned zoned gas-supply roller kiln and its control method for calcining NCM811 materials, solves the problems of high cost of using pure oxygen throughout the existing NCM811 calcining roller kilns, the inability to provide zoned gas supply in the low-temperature zone despite the lack of high oxygen requirements, and the easy cross-contamination between the two zones diluting the oxygen concentration in the high-temperature zone.

Description

Technical Field

[0001] This invention relates to the field of lithium battery cathode material preparation technology, and in particular to a zoned gas supply roller kiln and control method for calcining NCM811 material. Background Technology

[0002] NCM811 material, with its high specific capacity and cost advantages, has become a core cathode material for high-energy-density lithium-ion batteries. Its industrial production generally adopts a high-temperature solid-state method, in which the mixing, calcination, crystallization, and cooling of the precursor and lithium source are completed in a continuous roller kiln. The existing conventional process involves uniformly introducing high-concentration oxygen or pure oxygen along the entire length of the roller kiln to maintain the oxygen concentration inside the kiln at over 90% for a long period of time, in order to meet the oxidation and crystal phase formation requirements of the material throughout the calcination process.

[0003] In the calcination process, the material sequentially undergoes low-temperature heating, high-temperature reaction, and cooling stages along the roller conveyor. Studies have shown that when the internal temperature of the material is below 400℃, the main processes are dehydration and decomposition of the lithium source and precursor, before entering the critical oxidation stage for NCM811 crystal phase formation. In this range, air is sufficient to meet the atmosphere and heat transfer requirements. Only when the material temperature exceeds 400℃ does it enter the critical stages of oxidation reaction and crystal lattice formation, requiring a stable and suitable oxygen concentration to ensure the electrochemical performance of the material.

[0004] However, existing roller kilns generally adopt a uniform high-oxygen gas supply mode for the entire kiln without optimizing the atmosphere in different zones according to the calcination reaction mechanism. This results in a large amount of high-concentration oxygen being consumed in the low-temperature section, leading to low oxygen utilization and high production costs. If the low-temperature section is directly changed to be vented with air and the high-temperature section uses an oxygen-air mixture, there will be a problem of air diffusion from the low-temperature zone to the high-temperature zone. This will cause the oxygen concentration in the high-temperature zone to be continuously diluted, making it impossible to stably maintain the oxygen concentration range required by the process. Consequently, it will affect the sufficiency of the oxidation reaction and reduce the key electrochemical indicators of NCM811 materials, such as cycle stability and rate performance.

[0005] Currently, there is a lack of mature solutions for independent gas supply to the low-temperature and high-temperature zones of NCM811 calcining roller kilns, as well as effective atmosphere isolation between the two zones, making it difficult to significantly reduce oxygen consumption while ensuring material performance. Therefore, developing a roller kiln structure and control method that can achieve independent gas supply to different zones and effectively prevent crosstalk between the low-temperature zone and the high-temperature zone has become an urgent technical problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a zoned gas supply roller kiln and control method for calcining NCM811 materials, which solves the problems of high cost of using pure oxygen throughout the existing NCM811 calcining roller kiln, inability to provide zoned gas supply in the low-temperature zone when high oxygen is not required, and easy cross-contamination between the two zones diluting the oxygen concentration in the high-temperature zone.

[0007] To achieve the above objectives, the present invention provides a zoned gas-supply roller kiln for calcining NCM811 materials, including a sagger, rollers, an air inlet, a mixing inlet, an exhaust outlet, an upper partition wall, a lower partition wall, a radiant tube, and an atmosphere isolation structure. The interior of the roller kiln is divided into a low-temperature zone and a high-temperature zone along the material conveying direction, and a transition zone is provided between the low-temperature zone and the high-temperature zone. The rollers run horizontally through the low-temperature zone, transition zone, and high-temperature zone, with the top surface of the rollers supporting the saggers. The upper and lower partition walls enclose the kiln chamber, with radiant tubes installed inside. The low-temperature zone has an air inlet and an exhaust outlet, while the high-temperature zone has a mixing inlet. An atmosphere isolation structure is installed between the low-temperature and high-temperature zones. The air inlet is connected only to the kiln chamber in the low-temperature zone, while the mixing inlet is connected to the kiln chamber in the high-temperature zone. The mixing inlet is equipped with a gas mixing device.

[0008] Preferably, the atmosphere isolation structure includes a differential pressure control system, the low temperature zone and the high temperature zone are an integral sealed structure, the exhaust port is located at the top of the upper partition wall of the low temperature zone, and the high temperature zone does not have an exhaust port; the roller kiln adjusts the air intake and exhaust volume to make the pressure in the high temperature zone ≥5Pa higher than the pressure in the low temperature zone.

[0009] Preferably, the atmosphere isolation structure further includes a one-way physical barrier device, and the atmosphere isolation structure is located in the transition zone; the one-way physical barrier device is a high-temperature resistant flexible curtain or a one-way baffle.

[0010] Preferably, the physical partition device is made of ceramic fiber, aluminum silicate fiber and high temperature and oxidation resistant materials; the curtain is suspended and fixed at the lower end of the upper partition wall of the transition zone, and the gap between the lower end of the curtain and the lower partition wall is ≤5mm; the baffle is installed on the upper partition wall of the transition zone, and the lower end of the baffle is flush with the lower partition wall; the rotation speed of the rollers in the transition zone is 2 to 3 times that of the rollers in the low temperature zone and the high temperature zone.

[0011] Preferably, the temperature range of the low-temperature zone is room temperature to 400℃, and the temperature range of the high-temperature zone is 400℃ to 800℃; the radiant tube has independent temperature control in the low-temperature zone and the high-temperature zone.

[0012] Preferably, the sagger is driven by rollers to pass through the low temperature zone, the transition zone, and the high temperature zone in sequence; the radiant tubes are distributed between the upper partition wall and the lower partition wall, and the radiant tubes do not directly contact the rollers or the sagger.

[0013] A control method for a zoned gas-supply roller kiln for calcining NCM811 materials includes the following steps: S1. When the material is in the low temperature zone, air is only introduced into the low temperature zone through the air inlet, and the temperature of the low temperature zone is controlled from room temperature to 400℃. S2. After the material enters the high-temperature zone, a mixture of oxygen and air is introduced into the high-temperature zone through the mixing inlet to control the oxygen volume concentration in the high-temperature zone at 60%~65% and the temperature in the high-temperature zone at 400℃~800℃. S3. The atmosphere isolation structure prevents air from diffusing from the low-temperature zone to the high-temperature zone; S4. Real-time monitoring of oxygen concentration in high-temperature areas. When the oxygen concentration is below 60%, the oxygen ratio is automatically increased; when the oxygen concentration is above 70%, the air ratio is automatically increased.

[0014] Preferably, the atmosphere isolation structure achieves one-way sealing through a transition zone curtain or baffle. When material passes through, the curtain is passively opened and automatically reset, or the baffle is opened and closed in conjunction with the position of the sagger.

[0015] Preferably, the control method is suitable for the calcination of NCM811 material, and can also be used in the calcination process of NCM622, NCM523 and other ternary cathode materials.

[0016] Therefore, the present invention employs the above-mentioned zoned gas supply roller kiln and control method for calcining NCM811 materials, and the technical effects are as follows: 1. Solve atmospheric crosstalk in high and low temperature zones and ensure stable oxygen concentration in high temperature zone: By controlling the pressure difference or unidirectional physical isolation, prevent air from diffusing from the low temperature zone to the high temperature zone, avoid dilution of oxygen concentration in the high temperature zone, ensure that the oxidation reaction proceeds fully, and stably guarantee the electrochemical performance of NCM811 material.

[0017] 2. Reduce oxygen consumption and significantly reduce production costs: The low-temperature zone is only vented with air, and the high-temperature zone only requires a mixed gas with an oxygen concentration of 60%~65%, replacing more than 90% of the pure oxygen supply in the traditional kiln. Oxygen consumption is reduced by 44%~57%, directly and significantly reducing oxygen usage costs.

[0018] 3. Zoned gas supply matches the actual calcination reaction mechanism, improving process rationality: Precise gas supply according to the material temperature range, the low temperature section meets the decomposition requirements, and the high temperature section ensures the material oxidation, making the process more scientific and the atmosphere utilization more efficient. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the zoned gas supply roller kiln in the differential pressure control scheme of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the partitioned air supply roller kiln structure of the flexible high-temperature resistant baffle curtain, which is a one-way physical isolation scheme according to Embodiment 2 of the present invention. Figure 3 This is a schematic diagram of the partitioned gas supply roller kiln structure in the unidirectional physical isolation scheme of Embodiment 3 of the present invention, where the left baffle is open, the sagger is about to enter the transition zone, and the right baffle is closed. Figure 4This is a schematic diagram of the partitioned gas supply roller kiln structure in the unidirectional physical isolation scheme of Embodiment 3 of the present invention, in which the left baffle is closed, the sagger is about to leave the transition zone, and the right baffle is open. Figure 5 This is a schematic diagram of the partitioned gas supply roller kiln structure in Embodiment 3 of the present invention, which features a unidirectional physical isolation scheme with the left side baffle closed, the sagger completely removed from the transition zone, and the right side baffle closed.

[0020] Figure Labels 1. Sagger; 2. Roller; 3. Air inlet; 4. Mixing inlet; 5. Exhaust outlet; 6. Upper partition wall; 7. Lower partition wall; 8. Radiator tube; 9. Curtain; 10. Baffle. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0023] Example 1 This invention provides a zoned gas supply roller kiln for calcining NCM811 materials. The roller kiln is divided into a low-temperature zone, a transition zone, and a high-temperature zone along the material conveying direction. Through the zoned independent gas supply and atmosphere isolation structure, low-cost and high-performance production of NCM811 materials can be achieved.

[0024] The roller kiln includes a sagger (1), rollers (2), an air inlet (3), a mixing inlet (4), an exhaust outlet (5), an upper partition wall (6), a lower partition wall (7), radiant tubes (8), and an atmosphere isolation structure. Rollers (2) horizontally pass through the low-temperature zone, transition zone, and high-temperature zone, providing power for material conveying, and their top surface directly supports the sagger (1). In the transition zone, the rollers (2) rotate at 2-3 times the speed of those in the low-temperature and high-temperature zones, achieving rapid material flow in conjunction with physical partitions. The sagger (1) is placed on top of the rollers (2) and is used to load the NCM811 calcination raw material, which, as the rollers (2) rotate, sequentially passes through the low-temperature zone, transition zone, and high-temperature zone to complete the calcination process.

[0025] The upper partition wall 6 and the lower partition wall 7 form a sealed kiln chamber, separating the low-temperature zone, the transition zone, and the high-temperature zone, providing a closed atmosphere for calcination; physical partition devices are fixed on the partition walls. Radiant tubes 8 are arranged between the upper partition wall 6 and the lower partition wall 7, without direct contact with the rollers 2 and the sagger 1, enabling independent temperature control in the low-temperature zone and the high-temperature zone. The temperature control range of the low-temperature zone is room temperature to 400℃, and the temperature control range of the high-temperature zone is 400℃ to 800℃.

[0026] The zoned gas supply system includes gas supply to three zones: a low-temperature zone, a high-temperature zone, and a cooling zone. The air supply in the low-temperature zone is provided by only an air inlet 3 and an exhaust outlet 5. The air inlet 3 is connected to the kiln chamber of the low-temperature zone and only allows room temperature air to enter, without pure oxygen supply. The exhaust outlet 5 is located at the top of the upper partition wall 6 of the low-temperature zone.

[0027] The high-temperature zone is equipped with a mixed air inlet 4, which is connected to the kiln chamber of the high-temperature zone and introduces a mixed gas of oxygen and air to stabilize the oxygen volume concentration in the kiln at 60%~65%; the high-temperature zone does not have an independent exhaust port 5.

[0028] The cooling zone should be vented with a mixture of oxygen and air in the same way as the high-temperature zone, without the need for pure oxygen.

[0029] An atmosphere isolation structure is set in the transition zone between the low-temperature zone and the high-temperature zone to prevent air from the low-temperature zone from diffusing into the high-temperature zone. It includes a differential pressure control system and a one-way physical isolation device.

[0030] When using a differential pressure control system, since the roller kiln body is an integrally sealed structure, there is no physical barrier between the low-temperature zone and the high-temperature zone. By independently controlling the intake and exhaust volumes of the low-temperature zone and the high-temperature zone, the gas pressure in the high-temperature zone is made higher than that in the low-temperature zone, forming a slightly positive pressure airflow from the high-temperature zone to the low-temperature zone, thereby preventing the reverse diffusion of air from the low-temperature zone to the high-temperature zone.

[0031] No exhaust port is installed in the high-temperature zone; an electric regulating valve is installed at exhaust port 5 in the low-temperature zone to control the exhaust volume to be greater than or equal to the intake volume. This ensures that the pressure in the high-temperature zone is higher than that in the low-temperature zone (+5~+10 Pa). Pressure sensors are installed at both ends of the kiln body to monitor the pressure in both zones in real time and feed it back to the control system. This method is simple and can be implemented in existing roller kilns with almost no additional cost.

[0032] When using a unidirectional physical isolation device, a transition zone of one or two sagger lengths 1 is set between the low-temperature zone and the high-temperature zone. A unidirectional isolation structure is installed between the transition zone and both the low-temperature and high-temperature zones. This structure allows the sagger 1 and raw materials to pass through normally while preventing gas from flowing backward from the low-temperature zone to the high-temperature zone. The unidirectional physical isolation device is a high-temperature resistant flexible curtain 9 or a unidirectional baffle 10.

[0033] The flexible, high-temperature resistant baffle 9 is made of ceramic fiber or aluminosilicate fiber with a temperature resistance of ≥500℃. It is suspended from the top of the kiln chamber, with its lower end close to the partition wall (which extends upwards to be flush with the roller 2), and the gap is ≤5mm. The baffle 9 can be passively pushed open when the material passes through, and automatically reset by gravity after the material passes through, forming a one-way seal.

[0034] The vertically movable baffle 10 is made of ceramic fiber or aluminosilicate fiber with a temperature resistance of ≥500℃. This high-temperature resistant baffle 10 is installed on the partition wall at the bottom of the kiln chamber. When the sagger 1 is detected approaching the left baffle 10, the baffle 10 opens, and the sagger 1 moves rapidly to the transition zone, while the left baffle 10 falls. Simultaneously, the right baffle 10 opens, and the sagger 1 moves rapidly to the high-temperature zone, repeating this process. This design requires the rotational speed of the transition zone roller 2 to be 2-3 times higher than that of the other rollers.

[0035] like Figure 1 As shown, the present invention employs a zoned gas-supply roller kiln for calcining NCM811 materials. The roller kiln is arranged with a low-temperature zone and a high-temperature zone in sequence along the material conveying direction. There is no physical barrier between the two zones, and the kiln body is completely sealed. Gas flow is driven by pressure difference.

[0036] The kiln body is divided into two independent temperature zones: a low-temperature zone and a high-temperature zone. The temperature range of the low-temperature zone is from room temperature to 400℃. It is equipped with only an air inlet, which introduces ambient air by a fan and does not supplement pure oxygen. An exhaust port 5 is set at the top. The temperature range of the high-temperature zone is from 400℃ to 800℃. It is equipped with an oxygen inlet, an air inlet, and a gas mixing device, which can adjust the oxygen-air mixture. At the same time, the high-temperature zone does not have an exhaust or strictly controls the exhaust volume to be less than the air intake volume. Pressure sensors are also installed in both zones and connected to an automatic differential pressure control system.

[0037] The material is first introduced into a low-temperature zone with only air to meet the atmosphere and heat transfer requirements for the dehydration and decomposition reaction. After being transferred to a high-temperature zone, the gas mixing device is activated, and oxygen and air are introduced at an oxygen volume ratio of approximately 1.26:1 to stabilize the oxygen volume concentration in the high-temperature zone at 60%–65% (under a material layer thickness of 60 mm). At the same time, by adjusting the intake and exhaust volumes, a slight positive pressure difference of no less than 5 Pa is formed between the high-temperature zone and the low-temperature zone, preferably controlled at 5–10 Pa. This creates a directional airflow from the high-temperature zone to the low-temperature zone, preventing air from the low-temperature zone from spreading to the high-temperature zone. The system also monitors the oxygen concentration in real time, automatically increasing the oxygen ratio when it is below 60% and automatically increasing the air ratio when it is above 70%, achieving closed-loop stable control of the oxygen concentration.

[0038] This design effectively solves the problem of oxygen concentration dilution caused by cross-ventilation in high and low temperature zones, stably maintains oxygen content in the high-temperature zone, and ensures the stability of the electrochemical performance of NCM811 materials. In the low-temperature zone, ordinary air is used throughout the process without the need to consume pure oxygen, which can reduce oxygen consumption by more than 44%. Under the condition of a 60mm material layer, the oxygen cost per ton of product is reduced from 465 yuan to 261 yuan, saving 204 yuan per ton. Moreover, no structural modification of the kiln body is required, and process optimization can be achieved solely by relying on zoned gas supply and differential pressure control.

[0039] Example 2 like Figure 2As shown, the present invention is a flexible baffle curtain 9 scheme for a unidirectional physical isolation type zoned gas supply roller kiln. A transition zone is added between the low temperature zone and the high temperature zone, and a unidirectional physical isolation device is installed. The baffle curtain 9 is made of ceramic fiber or aluminosilicate fiber with a temperature resistance of not less than 500℃ and a thickness of 5-10mm. The width of the baffle curtain 9 is consistent with the 1.2m kiln chamber. It is suspended as a whole on the upper partition wall 6. The gap between the lower end and the lower partition wall 7 is controlled within 3mm, preferably not exceeding 5mm, so that it can be smoothly pushed open by the sagger 1 and can be automatically reset. At the same time, the low temperature zone, the high temperature zone and the transition zone adopt independent gas supply modes. Both the low temperature zone and the high temperature zone are provided with air inlets and exhaust outlets.

[0040] The system adopts a zoned independent gas supply control method. Conventional air is introduced into the low-temperature zone, while oxygen-air mixture with an oxygen concentration of 60% to 65% is supplied to the high-temperature zone. When the sagger 1 moves along the kiln channel, it can automatically push open the flexible baffle 9 to enter the high-temperature zone. After the sagger 1 passes through, the baffle 9 automatically droops and resets to form a sealing barrier, effectively preventing air from the low-temperature zone from flowing back into the high-temperature zone. In addition, the automatic control system performs closed-loop regulation of the oxygen concentration in the high-temperature zone to ensure the continuous and stable operation of the overall calcination process.

[0041] The air intake method in the transition zone can be a mixture of oxygen and air, that is, the oxygen concentration is controlled between the low temperature zone and the high temperature zone (21%~65%).

[0042] The flexible curtain 9 uses physical isolation to completely block atmospheric crosstalk between high and low temperature zones, providing a better sealing and isolation effect than simple differential pressure control solutions. After application, oxygen consumption can be reduced by 57%, and the oxygen cost per ton of product drops to 202 yuan, saving 263 yuan compared to the original cost. At the same time, the curtain 9 has a simple structure, is not prone to material jamming, and is resistant to high temperatures and oxidation, achieving reliable atmosphere sealing while ensuring smooth material flow.

[0043] Example 3 This invention relates to a one-way baffle 10 adapter structure for a one-way physical isolation type zoned gas supply roller kiln. Both the low-temperature zone and the high-temperature zone are equipped with air inlets and exhaust outlets. A transition zone is added between the low-temperature zone and the high-temperature zone, and a one-way physical isolation device is installed. The isolation device is a one-way baffle 10 with a thickness of 5~10mm and a width consistent with the width of the kiln chamber. The baffle 10 is installed on the partition wall of the roller kiln, and its lower end is flush with the partition wall.

[0044] When it is detected that the crucible 1 is about to enter the transition zone, the left baffle 10 opens, and the crucible 1 moves quickly to the transition zone, as shown. Figure 3 As shown; after the sagger 1 has fully entered the transition zone, the left baffle 10 closes and the right baffle 10 opens, as... Figure 4 As shown; when sagger 1 completely leaves the transition zone, the right baffle 10 closes, and the left baffle 10 closes again when sagger 1 will enter the transition zone, and this cycle repeats. Figure 5 As shown.

[0045] The air intake method in the transition zone can be a mixture of oxygen and air, that is, the oxygen concentration is controlled between the low temperature zone and the high temperature zone (21%~65%).

[0046] Taking a fabric thickness of 60mm as an example, compared with the traditional method of introducing pure oxygen into the entire kiln, the total oxygen consumption in this embodiment is reduced by 57%. If free air is taken into account, the cost per ton of NCM811 oxygen is reduced from 465 yuan to about 202 yuan, saving 263 yuan.

[0047] Therefore, this invention adopts the above-mentioned partitioned gas supply roller kiln and control method for calcining NCM811 materials. For the calcination process of NCM811 ternary cathode materials, the roller kiln is divided along the material direction into a low-temperature zone of room temperature to 400℃, a high-temperature zone of 400~800℃, and an intermediate transition zone. Only air is supplied to the low-temperature zone, while an oxygen-air mixture with an oxygen concentration of 60%~65% is supplied to the high-temperature zone. Atmosphere isolation between the two zones is achieved through pressure differential control (pressure in the high-temperature zone is ≥5Pa higher than that in the low-temperature zone) or through ceramic / alumina silicate fiber flexible baffles and one-way baffles, preventing low-temperature air from entering the high-temperature zone. With independent temperature control for each zone and automatic adjustment of oxygen concentration, oxygen consumption is reduced by more than 44% and production costs are significantly reduced while ensuring the electrochemical performance of the material. It is also compatible with the calcination of ternary materials such as NCM622 and NCM523, and is suitable for both new construction and renovation of existing kilns.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A zoned gas-supply roller kiln for calcining NCM811 materials, characterized in that, It includes a sagger, rollers, air inlet, mixing inlet, exhaust outlet, upper partition wall, lower partition wall, radiant tube, and atmosphere isolation structure. The interior of the roller kiln is divided into a low-temperature zone and a high-temperature zone along the material conveying direction, with a transition zone between the low-temperature zone and the high-temperature zone. The rollers run horizontally through the low-temperature zone, transition zone, and high-temperature zone, with the top surface of the rollers supporting the saggers. The upper and lower partition walls enclose the kiln chamber, with radiant tubes installed inside. The low-temperature zone has an air inlet and an exhaust outlet, while the high-temperature zone has a mixing inlet. An atmosphere isolation structure is installed between the low-temperature and high-temperature zones. The air inlet is connected only to the kiln chamber in the low-temperature zone, while the mixing inlet is connected to the kiln chamber in the high-temperature zone. The mixing inlet is equipped with a gas mixing device.

2. The zoned gas-supply roller kiln for calcining NCM811 material according to claim 1, characterized in that, The atmosphere isolation structure includes a differential pressure control system. The low-temperature zone and the high-temperature zone are an integral sealed structure. The exhaust port is located at the top of the upper partition wall of the low-temperature zone, and there is no exhaust port in the high-temperature zone. The roller kiln adjusts the inlet and outlet air volume to make the pressure in the high-temperature zone ≥5Pa higher than the pressure in the low-temperature zone.

3. A zoned gas-supply roller kiln for calcining NCM811 material according to claim 1, characterized in that, The atmosphere isolation structure also includes a one-way physical barrier device, which is located in the transition zone; the one-way physical barrier device is a high-temperature resistant flexible curtain or a one-way baffle.

4. A zoned gas-supply roller kiln for calcining NCM811 material according to claim 3, characterized in that, The physical partition device uses ceramic fiber, aluminum silicate fiber and high temperature and oxidation resistant materials; the curtain is suspended and fixed at the lower end of the upper partition wall in the transition zone, and the gap between the lower end of the curtain and the lower partition wall is ≤5mm; the baffle is installed on the upper partition wall in the transition zone, and the lower end of the baffle is flush with the lower partition wall; the rotation speed of the rollers in the transition zone is 2 to 3 times that of the rollers in the low temperature zone and the high temperature zone.

5. A zoned gas-supply roller kiln for calcining NCM811 material according to claim 1, characterized in that, The temperature range of the low-temperature zone is room temperature to 400℃, and the temperature range of the high-temperature zone is 400℃ to 800℃; the radiant tubes have independent temperature control in the low-temperature zone and the high-temperature zone.

6. A zoned gas-supply roller kiln for calcining NCM811 material according to claim 1, characterized in that, The sagger is driven by rollers to pass through the low temperature zone, transition zone and high temperature zone in sequence; the radiant tubes are distributed between the upper partition wall and the lower partition wall, and the radiant tubes do not directly contact the rollers or the sagger.

7. A control method for a zoned gas-supply roller kiln for calcining NCM811 material, based on the zoned gas-supply roller kiln for calcining NCM811 material according to any one of claims 1-6, characterized in that, Includes the following steps: S1. When the material is in the low temperature zone, air is only introduced into the low temperature zone through the air inlet, and the temperature of the low temperature zone is controlled from room temperature to 400℃. S2. After the material enters the high-temperature zone, a mixture of oxygen and air is introduced into the high-temperature zone through the mixing inlet to control the oxygen volume concentration in the high-temperature zone at 60%~65% and the temperature in the high-temperature zone at 400℃~800℃. S3. The atmosphere isolation structure prevents air from diffusing from the low-temperature zone to the high-temperature zone; S4. Real-time monitoring of oxygen concentration in high-temperature areas. When the oxygen concentration is below 60%, the oxygen ratio is automatically increased; when the oxygen concentration is above 70%, the air ratio is automatically increased.

8. The control method for a zoned gas-supply roller kiln for calcining NCM811 material according to claim 7, characterized in that, The atmosphere isolation structure achieves one-way sealing through a transition zone curtain or baffle. When materials pass through, the curtain is passively opened and automatically reset, or the baffle opens and closes in conjunction with the position of the sagger.

9. A control method for a zoned gas-supply roller kiln for calcining NCM811 material according to claim 7, characterized in that, The control method is applicable to the calcination of NCM811 materials, and can also be used in the calcination process of NCM622, NCM523 and other ternary cathode materials.

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