Furnace atmosphere control device and method
The furnace atmosphere control device automatically adjusts oxygen intake and exhaust to maintain high oxygen concentration and positive pressure, addressing inefficiencies in lithium-ion battery sintering furnaces, ensuring consistent product quality and reducing costs.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE
- Filing Date
- 2025-12-18
- Publication Date
- 2026-07-09
Smart Images
Figure 2026116205000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of battery materials. The present invention relates to a firing apparatus and method for a positive electrode material of a secondary battery. More specifically, the present invention relates to a furnace atmosphere control device and a method for a positive electrode material firing apparatus.
Background Art
[0002] Lithium-ion secondary batteries are high-efficiency rechargeable batteries. Depending on the positive electrode material, lithium-ion batteries can be classified into various types such as lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and ternary batteries. They are widely used in fields such as home appliances, new energy vehicles, and energy storage systems. The preparation of the positive electrode material for secondary batteries typically requires sintering in a high-purity oxygen atmosphere. A refractory crucible containing the positive electrode material is fired in a firing furnace at a temperature of 400°C to 1100°C according to the material characteristics.
[0003] For example, (Patent Document 1) describes a method for producing a positive electrode active material. The method includes a step of mixing lithium carbonate and a compound containing a metal element other than Li respectively, and a firing step of firing the mixture obtained in the mixing step in an oxidizing atmosphere to obtain a lithium composite compound. The firing step performs heat treatment in three stages, and the second and third heat treatment steps are performed in an oxidizing atmosphere with an oxygen concentration of 80% or more.
[0004] As another example, (Patent Document 2) describes a method for producing a lithium-containing composite oxide. The method includes a step of adjusting a raw material containing a lithium-containing hydroxide and a nickel-containing oxide or hydroxide in a reaction chamber under an oxidizing atmosphere to synthesize a lithium-containing composite oxide, a step of supplying oxygen to the reaction chamber, a step of discharging a mixed gas containing oxygen and water vapor generated in the step from the reaction chamber, a step of separating water vapor from the mixed gas, a step of recovering oxygen, and a step of supplying the oxygen recovered in the step to the reaction chamber.
[0005] The firing process for ternary cathode materials is controlled by cation diffusion. Therefore, during firing in an oxidizing atmosphere, a large amount of oxygen accumulates on the surface, increasing the number of cation vacancies, which accelerates cation diffusion and promotes firing. Thus, the firing process for ternary cathode materials must ensure a sufficient oxygen partial pressure. This differs considerably from other heat treatment processes, which typically aim to reduce the oxygen content in the atmosphere to avoid oxidation. Conversely, producing high-quality cathode materials requires firing the precursor material at high temperatures in a strongly oxidizing atmosphere.
[0006] During the firing process, the cathode material contained in the refractory saggar generates water vapor and carbon dioxide gas. It is difficult to expel the water vapor and carbon dioxide gas generated by the cathode material in the lower layer from the saggar, which has a serious impact on the oxygen partial pressure inside the firing furnace. When the concentration of carbon dioxide in the atmosphere increases, the reaction between lithium carbonate and nickel compounds tends to be greatly hindered, and the amount of carbonate component incorporated into the lithium composite compound crystal increases, which tends to lead to a decrease in charge / discharge capacity performance.
[0007] Manufacturers typically increase the oxygen partial pressure by reducing the firing rate, thereby reducing the amount of exhaust gas. However, increasing the firing rate also increases the unit energy consumption, which is undesirable for increasing production capacity. On the other hand, in firing furnaces with many layers of saggers, the amount of gas in contact with the material differs between the upper and lower layers. Combined with the thickness of the layers of the cathode raw material itself, insufficient oxygen partial pressure makes it difficult for oxygen to enter the raw material for efficient reaction. Saggers are usually semi-closed rectangular parallelepipeds, and the cathode material is placed inside the sagger for firing. The cathode material powder covers the sagger, and the atmosphere in the firing furnace cannot efficiently circulate with the atmosphere inside the sagger, leading to a decrease in the quality or uneven performance of the sintered product. The cathode material in the lower (bottom) and central parts of the sagger cannot adequately contact the sintering atmosphere, resulting in insufficient reaction and a decrease in sinter quality.
[0008] Therefore, the oxygen content in the atmosphere has a very significant impact on product quality and consistency. Currently, most manufacturers manually control the intake flow rate of oxygen-enriched gas entering the firing furnace using a gas circuit system consisting of main pipes, branch pipes, flow meters, control valves, etc. That is, the operator manually adjusts dozens of rotometers based on experience. This method places a high demand on the operator's skill level. It is often necessary to adjust the opening of the corresponding rotometer based on the technical indicators of the sintered powder and repeat this until a product that meets the requirements is sintered. This adjustment method is costly and difficult to process. In order to avoid these adjustments and any quality problems, operators often adjust the intake flow rate of oxygen-enriched gas, which leads to excessive oxygen consumption and increased production costs.
[0009] Furthermore, the pressure inside the furnace is extremely important during the sintering process of the cathode material. On the one hand, it is necessary to ensure that the pressure inside the furnace is higher than the pressure outside the furnace in order to prevent air from entering the furnace. On the other hand, it is also necessary to quickly remove the exhaust gases (water, carbon dioxide, etc.) generated during the sintering process. Conventional solutions involve continuously increasing the intake flow rate to maintain positive pressure. However, this requires a very expensive mass flow meter and also consumes a large amount of oxygen. Moreover, if the intake flow rate of the oxygen-enriched gas fluctuates, negative pressure is easily generated inside the furnace, allowing air to enter the furnace and affecting the quality of the cathode material.
[0010] Patent Document 3 discloses an L-shaped flue device for an atmosphere-protected kiln. A gate valve is installed in the flue pipe, and by controlling the opening and closing of the gate valve, the flue gas in the furnace chamber can be discharged to the outside. A flue outlet is provided at the top of the flue pipe, and the flue outlet communicates with the main flue pipe. The furnace chamber is provided between refractory bricks and alumina hollow ball bricks. Several furnace tube rollers are provided inside the furnace chamber. Bearing sheets are installed on the left and right outer walls of the refractory bricks. A sagger filled with material is placed on the furnace tube roller and is carried forward as the furnace tube roller rotates. However, the gate valve here can only be fully open or fully closed and has no adjustment function. This means that the degree to which the gate valve opens is fixed, and the degree to which the flue pipe outlet opens cannot be flexibly changed in order to adjust the partial pressure of oxygen inside the furnace.
[0011] There is also a conventional solution in which a rectangular damper is configured as the gate valve of the flue pipe. The damper is perpendicular to the flue pipe, and in many cases, adjusting its position requires an operator to climb onto the top of the furnace and manually pull out or retract the damper.
[0012] The desired outcome is to maintain positive pressure inside the firing furnace. It is necessary to find a control device and method that enables continuous, automated, on-demand control while minimizing waste of oxygen-enriched gas. [Prior art documents] [Patent Documents]
[0013] [Patent Document 1] Japanese Patent Publication No. 2016-110982A [Patent Document 2] Japanese Patent Publication No. 2010-269947 [Patent Document 3] China Patent Publication No. 209416082U Specification [Overview of the Initiative] [Problems that the invention aims to solve]
[0014] The general object of this disclosure is to provide furnace atmosphere control devices and methods, as well as firing furnace apparatus. The objective is to maintain a high oxygen concentration in the sintering atmosphere inside the firing furnace and to remove impurities from the atmosphere. This enables multi-stage heat treatment where each stage requires maintaining a high oxygen concentration in the atmosphere. Furthermore, it is desirable to set the sintering time long enough to ensure that the cathode material reacts sufficiently with oxygen.
[0015] Another objective is to address the challenge that existing manual systems require manual adjustments by operators, making it impossible to easily evaluate the effects of these adjustments in real time. [Means for solving the problem]
[0016] A first aspect of the present application discloses a furnace atmosphere control device, which is A control device comprising a flow control unit and / or an exhaust unit, wherein the flow control unit is connected to a gas sharing device that supplies oxygen-enriched gas into the furnace, and the exhaust unit is A cover plate that partially covers the outlet of an exhaust unit, A connecting rod, one end of which is connected to a crank and the other end of which is connected to a cover plate, the connecting rod is used to push and pull the cover plate to move it. A crank, with one end connected to an actuator and the other end pivotably connected to a connecting rod (via a crankpin), and An actuator that receives an input signal for performing angle and / or position control of a connecting rod. Includes an adjustment device, A sensor system comprising a sensor system selected from the group consisting of an oxygen concentration sensor, a moisture analyzer, a pressure sensor, a temperature sensor, and combinations thereof, A control unit that communicates with an adjustment device, a sensor system, and a gas supply device, and is programmed to adjust the intake flow rate of the oxygen-enriched gas and / or the area of the outlet of the exhaust unit, and the control unit; including.
[0017] Furthermore, when the intake flow rate of the oxygen-enriched gas remains constant, the control unit is programmed to adjust only the area of the outlet of the exhaust unit.
[0018] Furthermore, the rotational movement of the crank driven by the actuator is converted into the linear movement of the connecting rod.
[0019] Furthermore, the crank rotates from 0° to 90°, thereby linearly pushing and pulling the cover plate.
[0020] Furthermore, the control unit is programmed to receive signals indicating oxygen concentration, moisture content, pressure, and temperature from an oxygen concentration sensor, a moisture analyzer, a pressure sensor, and a temperature sensor, respectively.
[0021] Furthermore, the pressure sensor indicates a pressure value of 0 to 300 Pa, preferably 250 Pa to 300 Pa.
[0022] Furthermore, the pressure sensor indicates that the pressure value varies in a continuous cycle.
[0023] The second aspect of the present application discloses a positive electrode material firing apparatus including a firing furnace, at least one gas supply device, and a furnace atmosphere control device according to the first aspect.
[0024] The third aspect of the present application discloses a method for continuously and real-time controlling the furnace atmosphere. In this method, based on at least one measured factor data, the characteristic parameters are adjusted using the furnace atmosphere control device according to the first aspect, and the characteristic parameters include the moving distance of the cover plate along the axial direction of the connecting rod, the area of the outlet of the exhaust unit, and / or the flow rate value of the flow adjustment unit.
[0025] Furthermore, each factor data includes the intake flow rate, oxygen concentration, temperature, pressure, and water content of the oxygen-enriched gas.
[0026] Furthermore, based on each factor data, the control unit performs the following controls according to the generated characteristic parameters: (1) Reduction or increase in the intake flow rate of oxygen enriched gas supplied relative to the set value or (2) Reduction or increase of the area of the exhaust outlet of the exhaust unit or (3) Increase the intake flow rate of oxygen enriched gas supplied relative to the set value and increase the area of the outlet of the exhaust unit or (4) Reduction of the intake flow rate to which oxygen enriched gas is supplied relative to the set value and reduction of the outlet area of the exhaust unit. Execute
[0027] Furthermore, the furnace atmosphere control method is: (i) Transmitting the oxygen concentration, temperature, pressure, and moisture content measured by each sensor to the control unit and comparing them to stored or default preset values; (ii) A step of generating a control signal by a control unit, wherein the control signal is used to adjust each characteristic parameter, Includes.
[0028] Furthermore, standard or historical factor data related to the reactor process, as well as exhaust gas and their corresponding characteristic parameters, are utilized and stored in the control unit.
[0029] Compared to prior art, the technical solution provided by this application has the following advantages: 1. The furnace atmosphere control device of the present invention enables the sintering atmosphere inside the firing furnace to be maintained at a high oxygen concentration and continuous positive pressure, thereby ensuring the firing effect of the cathode raw materials. 2. The furnace atmosphere control device and method of the present invention achieve uniform exposure of the positive electrode raw material to the oxygen-enriched gas, enable sufficient contact between the oxygen-enriched gas and the raw material in the calcination furnace, and reduce the dead zone. 3. The furnace atmosphere control method of the present invention achieves automatic, real-time, and accurate adjustment, eliminating the need for frequent manual operation by the operator, and is safe and efficient.
[0030] The advantages and purpose of this invention can be further understood through the following detailed description of the invention and the drawings. [Brief explanation of the drawing]
[0031] [Figure 1] Figure 1 shows a top view of a furnace atmosphere control device in one embodiment of the present invention. [Figure 2] Figure 2 shows a schematic diagram of a furnace atmosphere control device in one embodiment of the present invention. [Figure 3] Figure 3 shows a chart illustrating the furnace pressure trend within 12 hours in one embodiment of the present invention. [Figure 4] Figure 4 shows a furnace pressure trend chart for randomly selected cycles in one embodiment of the present invention. [Figure 5] Figure 5 shows the capacity retention rate results of a secondary battery assembled using the positive electrode material prepared in one embodiment of the present invention. [Figure 6] Figure 6 shows the capacity retention rate results of secondary batteries assembled using the positive electrode material prepared in the comparative example of the present invention. [Modes for carrying out the invention]
[0032] In the diagram, 101 represents the actuator, 102 represents the crank, 103 represents the crankpin, 104 represents the connecting rod, 105 represents the exhaust unit outlet, 106 represents the limiting block, 107 represents the guide rail, and 108 represents the cover plate.
[0033] Specific embodiments of the present application will be described in detail below with reference to the drawings. However, the present application should not be understood as being limited to such embodiments described below, and the technical concepts of the present application may be implemented in combination with other known technologies or other technologies having the same function as those known technologies.
[0034] Explanation of terms In the following descriptions of specific embodiments, many directional terms are used to clearly indicate the structure and mode of operation. However, terms such as "front," "rear," "left," "right," "outside," "inside," "outside," "inside," "axial," and "radial" should be understood as terms of convenience and not as restrictive terms.
[0035] In the following descriptions of specific embodiments, orientations or positional relationships indicated by terms such as “length,” “width,” “top,” “bottom,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inside,” and “outside” are based on the orientations or positional relationships shown in the drawings and are merely for the convenience of simplified explanation. It should be understood that these do not indicate or imply that the referred device or element must be in a particular orientation or must be constructed and operated in a particular orientation, and therefore should not be construed as limitations on the present application. Furthermore, where a first structure is described as being located “above” or “below” a second structure, this should be understood to mean that the first structure is located away from or near the horizontal plane.
[0036] Furthermore, the terms “first” and “second” are used for descriptive purposes only and should not be interpreted as indicating or implying the relative importance of the technical features described or as implicitly indicating a quantity. Accordingly, a feature defined by “first” or “second” may explicitly or implicitly include one or more such features. In this description, “plural” means two or more unless otherwise clearly defined. Similarly, determiners such as “a” or “one” appearing herein do not refer to a limitation on quantity, but describe a technical feature that has not appeared previously. Likewise, unless a noun is modified by a specific determiner, it should be considered herein to include both singular and plural forms, and a technical solution may include its singular or plural technical feature. Similarly, modifiers such as “about” and “approximately” appearing before numbers herein generally include the number itself, and their specific meanings should be understood in conjunction with the context.
[0037] In this application, “at least one (item)” should be understood as referring to one or more items, and “plural” as referring to two or more items. “And / or” is used to describe the relationship between related things and indicates that three relationships may exist. For example, “A and / or B” may indicate that only A exists, only B exists, and both A and B exist, where A and B may be singular or plural. The letter “ / ” generally indicates that the preceding and following related things are in an “or” relationship. “At least one of the following” or similar expressions refer to any combination of these items, including any single item or any combination of multiple items. For example, at least one of a, b, or c may represent a, b, c, “a and b”, “a and c”, “b and c”, or “a and b and c”, where a, b, c may be singular or plural.
[0038] In this application, unless otherwise explicitly specified and limited, terms such as “install,” “connect,” “link,” and “fix” should be understood in a broad sense. For example, a connection may be fixed, detachable, integral, mechanical, or electrical, direct or indirect through an intermediate medium, or internal communication between two elements or an interaction relationship between two elements. Those skilled in the art will understand the specific meaning of the above terms in this application according to the specific context. “Fixed connection,” “fixed connection,” or “immovably connected” is understood to mean that the connection between two or more structural members is not configured to provide relative motion. One embodiment of a fixed connection is a single welded joint or a single bolted connection, and in some cases, multiple welds and multiple bolted connections. “Movably connected,” “movable,” or “movable connection” is understood to mean a connection between two or more structural members that allows for horizontal and / or vertical relative movement between members under extreme dynamic loads. Such connections typically do not allow movement under static loads or general dynamic loads (e.g., loads imposed by light / moderate winds).
[0039] As used herein, the terms “unit,” “piece,” “object,” and “module” refer to a unit for performing at least one function and operation, which may be implemented by hardware components, software components, or a combination thereof.
[0040] The term “axial” refers to a direction generally parallel to the axis of rotation, axis of symmetry, or centerline of one or more components. For example, in a cylinder having a centerline and opposing circular ends, the “axial” direction may refer to the direction extending parallel to the centerline between the opposing ends. Furthermore, as used herein, the term “radial” may refer to the direction or relationship of a component to a line extending outward perpendicularly from a shared centerline, axis, or similar reference point.
[0041] In addition, in this specification, "firing furnace" refers to a device for heating and firing raw materials. For example, terms such as "furnace," "kiln," "heating device," "sintering device," and "sintering furnace" may be used instead.
[0042] The terms "high pressure" and "medium pressure" mean that high pressure is higher than medium pressure, and the difference between the two may be relatively small.
[0043] The terms "high temperature" and "low temperature" mean that a high temperature is higher than a low temperature, and the difference between the two may be relatively small.
[0044] As used herein, the term “communication” means the ability to send and receive information, data, signals, controls, and commands over any known technology. For example, communication between components of a furnace atmosphere control device may be performed over one or more technologies, including but not limited to fixed wires or wireless networks, such as local area networks (LANs), wireless local area networks (WLANs), wide area networks (WANs), personal area networks (PANs), wireless personal area networks (WPANs), telephone lines (cellular networks or circuit-switched networks, etc.), internal networks, external networks, peer-to-peer networks, virtual private networks (VPNs), the Internet, or other communication networks / links.
[0045] The sintering furnace includes sequentially connected heating, insulating, and cooling spaces, in which the cathode material is gradually raised from an initial temperature until the temperature stabilizes. Furthermore, this temperature should be reasonably constant or maintained near the desired average temperature. Sintering may last from 50 to 300 minutes at a sintering temperature in the range of 400°C to 800°C. The sintering time may involve gradually heating the lithium material at a controlled rate by increasing the temperature.
[0046] Therefore, the term "standard" is synonymous with terms such as "target," "setting," or "pre-set," which are used by those skilled in the art, for example, in expressions such as "pre-set value" or "set value."
[0047] An oxygen-enriched atmosphere refers to bringing an oxygen-enriched gas into complete contact with the raw materials within the sintering device through a corresponding oxygen supply device. The oxygen-enriched gas can have maximum contact with the mixture. The oxygen concentration of the oxygen-enriched gas is preferably 90% or higher, more preferably 91%, 93%, 95%, 97%, or even 99% or higher.
[0048] The oxygen supply device may consist of, for example, a gas tank or gas cylinder for storing oxygen, a VSA (vacuum swing adsorption) type, PVSA (pressure vacuum swing adsorption), PTSA (pressure thermal swing adsorption) type, a gas separation membrane type, or other types of oxygen generation devices. The oxygen supply device provides oxygen-enriched gas to the calcination furnace through an oxygen transport device. The molar concentration of oxygen in the oxygen-enriched gas is here at least 90%, more preferably at least 93%, more preferably at least 95%, and most preferably at least 99%.
[0049] The term “control unit” encompasses units that control at least one firing furnace or units that can independently control all or some components of a firing furnace. A control unit may include at least one of the following: a microcontroller, a microprocessor, or a computer. The method of communication between the control unit and each component is not limited. Conveniently, a control unit may include a programmable controller, also known as a PLC (Programmable Logic Controller) system, i.e., a control system for industrial processes. A programmable controller may include a human-machine interface for monitoring and a digital communication network. A PLC system may include several modular controllers that control their respective subsystems. According to one feasibility, a control unit may include a human-machine interface, which may include an input interface (e.g., a touch screen) that allows a user to input commands to the control unit and / or factor data particularly relevant to the firing process and emissions.
[0050] An "actuator" or "operator" is a mechanism by which a control system, such as a mechanical or electrical system, acts upon the environment. Specifically, an actuator can be used to control the operation of a device.
[0051] Specific embodiments of this application will be described in detail below with reference to the drawings. Embodiments may extend to multiple figures in the drawings. The same reference numerals in embodiments generally indicate the same or corresponding elements. Thus, the descriptions of embodiments are incorporated into one another, and descriptions of subjects common to embodiments are generally not repeated herein. Unless otherwise specified, each aspect or embodiment defined herein may be combined with any other aspect or embodiment. In particular, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous.
[0052] As shown in Figures 1 and 2, the furnace atmosphere control device in this application is A control device comprising a flow control unit and / or an exhaust unit, wherein the flow control unit is connected to a gas sharing device that supplies oxygen-enriched gas into the furnace, and the exhaust unit is A cover plate 108 that partially covers the outlet 105 of the exhaust unit, A connecting rod 104, wherein one end of the connecting rod 104 is connected to the crank 102 and the other end is connected to the cover plate 108. One end of the crank 102 is connected to the actuator 101, and the other end is pivotably connected to the connecting rod 104 via a crank pin 103, and Actuator 101, which receives an input signal for performing angle and / or position control of the connecting rod 104. Includes an adjustment device, A sensor system comprising an oxygen concentration sensor, a moisture analyzer, a pressure sensor, and / or a temperature sensor, A control unit, the control unit communicating with an adjustment device, a sensor system, and a gas supply device, and the control unit being programmed to adjust the intake flow rate of oxygen-enriched gas and / or the area of the outlet of the exhaust unit, Includes.
[0053] Preferably, the control unit is programmed to adjust only the area of the exhaust unit outlet 105, i.e., only the position of the cover plate 108.
[0054] The cover plate 108 is a sliding cover that slides along the guide rail 107.
[0055] The connecting rod 104 is used to push and pull the cover plate 108 to move it, thereby changing the position of the cover plate 108 and, consequently, changing the area of the exhaust unit outlet 105. Different positions of the cover plate 108 correspond to different areas of the exhaust unit outlet.
[0056] The base of the crank 102 is attached to the end region of the crank by welding or other means. For example, the crank pin 103 is configured to pivotally connect the crank 102 and the connecting rod 104.
[0057] The control unit is programmed to receive signals indicating the oxygen concentration, moisture content, pressure, and temperature inside the furnace from an oxygen concentration sensor, a moisture analyzer, a pressure sensor, and a temperature sensor, respectively. The control unit may be an analog control system or a digital control system. Preferably, the control unit is mathematically and programmable. The control unit generally controls the batch process of the firing furnace, adjusting, for example, the intake flow rate of oxygen enrichment gas and the mechanical drive of the exhaust unit. Each component of the control unit may consist of an information processing device (e.g., a computer, a server) having memory, a processor, and software programs, dedicated circuits, firmware, etc. Various setting values are input to the control unit or stored in memory. Various setting values (which are also used as input data, as described later) include, for example, specifications related to the firing furnace (type, volume, capacity), data related to materials, process data, required energy values, temperature setting values, batch data, etc., and these are stored in memory.
[0058] The control unit associates the measured furnace temperature, pressure, moisture content, oxygen concentration, oxygen enrichment gas intake flow rate, cover plate position, or exhaust unit outlet area, and stores them in memory.
[0059] The oxygen-enriched gas enters the furnace via a flow rate control unit. The flow rate control unit performs proportional control over the oxygen-enriched gas flow rate based on signals from the control unit, allowing for increases or decreases in the oxygen-enriched gas intake flow rate. Gases, including steam and carbon dioxide, discharged from the furnace exit through an exhaust unit. The exhaust unit communicates with the outside of the furnace through its inlet.
[0060] The firing furnace has walls that define the atmosphere inside the furnace, including side walls, walls, and a bottom wall. The atmosphere inside the furnace region is influenced in a different way by at least one furnace parameter (factor data) including, but not limited to, the intake flow rate of oxygen-enriched gas, oxygen concentration, moisture content, temperature, and pressure.
[0061] A pressure sensor is used to measure the total pressure in the furnace atmosphere. An oxygen concentration sensor reflects the partial pressure of oxygen in the furnace atmosphere. Multiple pressure sensors and other sensors may be installed at different locations in each furnace. A pressure sensor may be located near the saggar and measure the atmosphere to which the cathode material is exposed. A sampling pipe may be used, with one end of the sampling pipe extending outward through the wall of the firing furnace and the other end exposed to an opening inside the furnace.
[0062] For example, a pressure sensor is electrically connected to a control unit. The control unit receives a signal from the pressure sensor and adjusts the position of the cover plate by communicating with the exhaust unit.
[0063] The oxygen concentration sensor, moisture analyzer, and pressure sensor can all take samples from the furnace atmosphere using sampling piping known to those skilled in the art. The inlet for the oxygen-enriched gas flowing from the gas supply device is located at the bottom of the firing furnace. The sampling piping for the oxygen concentration sensor extends away from the oxygen-enriched gas inlet to a position near the top of the firing furnace. The oxygen concentration sensor includes zirconia or any other oxygen sensor suitable for measuring oxygen in a highly oxidizing atmosphere. As used herein, the oxygen concentration sensor is capable of measuring the oxygen concentration in the furnace atmosphere. The temperature sensor is mounted on the furnace wall or directly exposed to the furnace atmosphere.
[0064] A temperature sensor is any sensor configured to perform temperature measurement by contact, such as a thermocoupler. In a non-limiting example, continuous measurement may be performed by one or more installed thermocouplers, each of which is either incorporated into or open to the furnace atmosphere, to continuously measure the temperature inside the furnace.
[0065] Moisture analyzers can effectively measure the absolute value of moisture content in high-temperature environments (temperatures above 150°C).
[0066] Examples of flow rate control units include mass flow controllers or control valves. A pressure control unit may be provided instead of, or together with, the flow rate control unit. Examples of pressure control units include pressure gauges, pressure regulating valves, back pressure valves, etc.
[0067] During the pushing and pulling process, the cover plate 108 tends to strike the inner wall of the exhaust unit, generating debris and causing malfunctions. Therefore, the limiting block 106 is installed on the side of the exhaust unit outlet according to the position where the opening of the exhaust unit outlet is largest and the positions of the connecting rod 104 and the cover plate 108, to ensure that the cover plate 108 is not pressed against the inner wall of the exhaust unit outlet. Here, the exhaust unit outlet may be an opening or a pipe structure. Here, the cover plate 108 may be in the form of a sliding cover.
[0068] In other words, the actuator 101 (or operator) is a drive execution device that receives an input signal and performs opening, closing, and angle / position control. The actuator 101 drives the rotation of the crank 102, which is converted into linear motion of the connecting rod 104, thereby allowing the cover plate 108 to move away from or toward the exhaust unit outlet 105, thereby changing the area of the outlet. When driven by an electrical signal, the crank 102 rotates 0 to 90°, thereby linearly pushing and pulling the cover plate 108.
[0069] If the intake flow rate of oxygen-enriched gas remains constant, the discharge rate can be altered by changing the physical position of the cover plate, thereby affecting the furnace pressure. For example, if the cover plate is moved to reduce the area of the exhaust unit outlet, the partial pressure of oxygen inside the furnace will increase.
[0070] The device and method of the present invention can achieve control of continuous fluctuations in furnace pressure by continuously measuring each factor data in real time. In this type of process, it is necessary to expose the cathode raw material to oxygen-enriched gas very uniformly. For example, all saggars in any firing furnace can be exposed to sufficient oxygen. In some methods of the prior art, it has been observed that contact between oxygen and raw material is low inside the saggars inside the firing furnace, especially in the deep parts. Conversely, it has been found that raw material on the surface has a better opportunity to come into contact with oxygen. Therefore, in the case of saggars or raw material located deep inside, the firing quality is not very good. These drawbacks can be overcome by the device and method of the present invention. The cathode raw material inside the saggar itself has a layer thickness, and if the oxygen partial pressure is insufficient, it becomes difficult for oxygen to pass through the material. To address this problem, one of the objectives of the present invention is to create appropriate fluctuations and stirring of the oxygen partial pressure inside the furnace through continuous control of furnace pressure, thereby quickly and rapidly reducing the dead zone of oxygen concentration. Therefore, oxygen does not rely purely on natural diffusion as in conventional technology, but rather comes into sufficient contact with the cathode raw materials for the reaction.
[0071] Exemplary, the furnace pressure (gauge pressure) inside the furnace is maintained between 0 and 300 Pa to maintain a positive pressure environment inside the furnace. In all continuous firing furnaces, the atmospheric pressure is controlled to be positive with respect to the gauge pressure. Figure 3 shows a furnace pressure trend chart over a period of 12 hours, calculated in 30-second cycles, i.e., the gauge pressure is read and recorded every 30 seconds. The gauge pressure is stably maintained at a positive pressure in the range of 250-300 Pa. As used above, the movement of the cover plate from its initial position to the maximum outlet area and back to the initial position or vice versa is called one cycle. The pressure sensor shows that the gauge pressure inside the furnace fluctuates in a continuous cycle, like a "pulse" fluctuation, i.e., the cover plate moves continuously within one cycle. Figure 4 shows a furnace pressure trend chart for 22 randomly selected cycles. It can be seen that the furnace pressure fluctuates continuously in the range of 0-300 Pa, creating furnace pressure turbulence and promoting the passage of oxygen through the positive electrode material.
[0072] The gas supply device is connected to the mass flow controller at the inlet of each firing furnace. The gas supply device communicates with the oxygen source and is used to optimize the intake flow rate of oxygen-enriched gas to each firing furnace to maintain a high oxygen concentration. Simultaneously, carbon dioxide, water vapor, and other impurities are expelled, and an ideal atmospheric flow direction is maintained.
[0073] The intake flow rate of oxygen-enriched gas at the inlet of each firing furnace may be fixed or variable. One or more standard operating modes and corresponding standard parameters may remain constant over time, for example, the intake flow rate of oxygen-enriched gas may not change as specified.
[0074] In multi-stage heat treatment, it is required to maintain a high oxygen concentration in the atmosphere at each stage. Sintering furnace pressure sensors and various other sensors are installed at selected locations to monitor the flow pattern of the furnace atmosphere. Parameters including, but not limited to, temperature, oxygen concentration, moisture, and carbon dioxide concentration are preferably used to determine the optimal operation of the sintering furnace atmosphere control device by confirming whether the sintering furnace atmosphere is operating under optimal conditions and by correlating the atmosphere conditions with the quality of the cathode raw materials.
[0075] The above-described furnace atmosphere control device controls the furnace atmosphere. A standard or historical data model related to the furnace process and exhaust is used, which is generated from furnace parameters and includes characteristic parameters corresponding to each factor data, such as oxygen concentration, temperature, pressure, and moisture content, which are related to the atmosphere inside the furnace. The characteristic parameters include the corresponding travel distance of the cover plate along the axial direction of the connecting rod, the area of the outlet of the exhaust unit, and / or the flow valve of the flow control unit.
[0076] Each sensor can be used to continuously or intermittently measure various factor data of the furnace and communicate with the control unit. Simultaneously, the corresponding characteristic parameters are stored in the control unit.
[0077] In the control step, based on each factor data, the control unit performs the following controls according to the characteristic parameters: (1) If the area of the exhaust unit outlet remains unchanged, increase or decrease the intake flow rate of the oxygen-enriched gas supplied to the furnace from the set value, (2) If the intake flow rate of the oxygen-enriched gas does not change, move the cover plate along the axial direction of the connecting rod, thereby increasing or decreasing the area of the outlet of the exhaust unit, (3) Increase the intake flow rate of oxygen-enriched gas supplied to the furnace from the set value, move the cover plate so that the area of the exhaust unit outlet is increased, or (4) Reduce the intake flow rate of the oxygen-enriched gas supplied to the furnace from the set value and move the cover plate so that the area of the exhaust unit outlet is reduced.
[0078] Oxygen-enriched gas flows into the firing furnace, and the firing of the cathode material begins. The sensor system functions to compare the actual measured value with a preset value. The preset value may be set by the operator or may be a standard value obtained based on past tests. If the pressure value inside the furnace is lower than the preset value, the control unit sends a signal to the actuator to move the position of the cover plate through the cooperation of the crank and connecting rod, reducing the outlet area of the exhaust unit. Alternatively, the control unit sends a signal to the flow control unit to increase the intake flow rate of oxygen-enriched gas. The control unit continues to read the pressure sensor reading until the gauge pressure is equal to or greater than the pressure set value.
[0079] If the furnace pressure is greater than the pressure setpoint, the control unit sends a signal to the actuator to move the cover plate and increase the outlet area of the exhaust unit. The above control steps can be performed in a continuous cycle.
[0080] The oxygen concentration, temperature, pressure, and moisture content data measured by each sensor are transmitted to the control unit and stored or compared to default preset values. The preset values correspond to the characteristic and operating parameters of each factor data that are generally expected at a given stage of the calcination furnace, including one or more flow rates of oxygen-enriched gas entering the furnace, controlled by a flow rate adjustment unit.
[0081] In this case, the control unit generates control signals used to adjust various characteristic parameters, such as the travel distance of the cover plate along the axial direction of the connecting rod, the area of the exhaust unit's outlet, and / or the flow rate of the flow rate adjustment unit.
[0082] When multiple firing furnaces are operating simultaneously, the preset values for each factor data in each firing furnace may differ and may be dynamically adjusted by the control unit based on sensor measurements.
[0083] Capacity retention is an important indicator of the cycle stability of cathode materials.
[0084] A positive electrode material prepared using the device and method of this invention was assembled into a secondary battery according to a conventional test method. 200 charge-discharge cycles were performed at constant current, a voltage range of approximately 3.0V to 4.2V, and room temperature (approximately 20 to 25°C). The capacity retention rate results from the cycle charge-discharge test are shown in Figure 5.
[0085] The capacity retention rate of the secondary battery after the nth cycle was calculated using the following formula: Capacity retention rate (%) = [Discharge capacity in the nth cycle / Discharge capacity in the first cycle] × 100%.
[0086] As a comparative example, a secondary battery was constructed by assembling a comparative positive electrode material obtained without constructing the device of the present invention for testing purposes. The capacity retention rate of the secondary battery after multiple cycles is shown in Figure 6.
[0087] Figure 5 shows a very well-balanced capacity retention rate. This indicates that both the surface layer and the bottom layer (deep layer) of the cathode material achieved sufficient firing and uniform sintering efficiency. The performance of the prepared cathode material is more stable.
[0088] On the other hand, in the comparative cathode material shown in Figure 6, the capacity retention gap gradually increased after 50 cycles. As the number of cycles increased, the stability of the capacity retention decreased.
[0089] This means that the degree of infiltration and diffusion of oxygen-enriched gas into the cathode material is a major factor affecting the electrochemical performance of the cathode material. The device and method of this application can efficiently improve capacity retention, cycle performance, and rate performance.
[0090] Only preferred specific embodiments of the present application are described herein. The above embodiments are not limitations of the present application and are used solely to illustrate the technical solutions of the present application. All technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present application are within the scope of the present application. [Explanation of Symbols]
[0091] 101 Actuator 102 Crank 104 Connecting Rod 105 Exhaust unit outlet 106 Restriction Block 107 Guide rail 108 Cover Plate
Claims
1. A furnace atmosphere control device, A control device comprising a flow control unit and / or an exhaust unit, wherein the flow control unit is connected to a gas sharing device that supplies oxygen-enriched gas into the furnace, and the exhaust unit is A cover plate (108) that partially covers the outlet (105) of the exhaust unit, A connecting rod (104), wherein one end of the connecting rod (104) is connected to a crank (102) and the other end is connected to the cover plate (108), and the connecting rod (104) is used to push and pull the cover plate to move it. One end of the crank (102) is connected to an actuator (101), and the other end is pivotably connected to the connecting rod (104), and Actuator (101) that receives an input signal for performing angle and / or position control of the connecting rod (104) Includes an adjustment device, A sensor system comprising a sensor system selected from the group consisting of an oxygen concentration sensor, a moisture analyzer, a pressure sensor, a temperature sensor, and combinations thereof, A control unit, the control unit communicating with the adjustment device, the sensor system, and the gas supply device, and the control unit being programmed to adjust the intake flow rate of the oxygen enrichment gas and / or the area of the outlet (105) of the exhaust unit, A furnace atmosphere control device, including...
2. The furnace atmosphere control device according to claim 1, wherein the intake flow rate of the oxygen-enriched gas remains constant, and the control unit is programmed to adjust only the area of the outlet (105) of the exhaust unit.
3. The furnace atmosphere control device according to claim 1, wherein the rotational motion of the crank driven by the actuator is converted into linear motion of the connecting rod.
4. The furnace atmosphere control device according to claim 3, wherein the crank rotates from 0° to 90°, thereby linearly pushing and pulling the cover plate.
5. The furnace atmosphere control device according to claim 1, wherein the control unit is programmed to receive signals indicating oxygen concentration, moisture content, pressure, and temperature from the oxygen concentration sensor, the moisture analyzer, the pressure sensor, and the temperature sensor, respectively.
6. The furnace atmosphere control device according to claim 1, wherein the pressure sensor indicates that the pressure value fluctuates in a continuous cycle.
7. A cathode material firing apparatus comprising a firing furnace, at least one gas supply device, and a furnace atmosphere control device according to any one of claims 1 to 6.
8. A continuous real-time furnace atmosphere control method, wherein, based on at least one measured factor data, characteristic parameters are adjusted using a furnace atmosphere control device according to any one of claims 1 to 6, the characteristic parameters including the travel distance of the cover plate along the axial direction of the connecting rod, the area of the outlet of the exhaust unit, and / or the flow rate value of the flow adjustment unit.
9. The furnace atmosphere control method according to claim 8, wherein each factor data includes the intake flow rate of the oxygen-enriched gas, the oxygen concentration, the temperature, the pressure, and the water content.
10. Based on each factor data, the control unit performs the following controls in accordance with the generated characteristic parameters: (1) Reduction or increase of the intake flow rate to which the oxygen enriched gas is supplied relative to the set value or (2) Reduction or increase of the area of the outlet of the exhaust unit or (3) An increase in the intake flow rate to which the oxygen enriched gas is supplied relative to the set value and an increase in the area of the outlet of the exhaust unit or (4) Reduction of the intake flow rate to which the oxygen enriched gas is supplied relative to the set value and reduction of the area of the outlet of the exhaust unit A furnace atmosphere control method according to claim 8, which performs the following:
11. (i) Transmitting the oxygen concentration, temperature, pressure, and moisture content measured by each sensor to the control unit and comparing them to stored or default preset values; (ii) A step of generating a control signal by the control unit, wherein the control signal is used to adjust each characteristic parameter, The furnace atmosphere control method according to claim 8, including the method described in claim 8.