Carbon thermal reduction regeneration method of waste lithium iron phosphate battery

Abstract

The invention discloses a carbon thermal reduction regeneration method of a waste lithium iron phosphate battery, and relates to the related field of secondary battery regeneration, and the method comprises the following steps: carrying out visual positioning and disassembly separation on the waste lithium iron phosphate battery to obtain a battery positive electrode black powder material, putting the battery positive electrode black powder material into an air atmosphere heating furnace, and carrying out oxidation treatment control to obtain a positive electrode oxidation product; calculating the raw material ratio based on the component information of the positive electrode oxidation product, and determining the raw material ratio dosage; putting the positive electrode oxidation product, a lithium source, an iron source, a phosphorus source and a carbon source reducing agent into mixing equipment according to the raw material proportioning dosage, and mixing; and putting the raw material mixture into a nitrogen atmosphere sintering furnace for sintering carbon thermal reduction according to a segmented temperature control sintering strategy, and monitoring, regulating and controlling battery regeneration based on a PID controller and a temperature sensing device. The technical problem that the quality of a regenerated material is unstable in carbon thermal reduction regeneration of the existing waste lithium iron phosphate battery is solved, and the technical effect of high-quality preparation of the regenerated material is achieved.

Description

Technical Field

[0001] The present application relates to the field of secondary battery regeneration, and in particular to a carbon thermal reduction regeneration method for waste lithium iron phosphate batteries. Background Art

[0002] With the rapid development of the new energy vehicle industry, the number of spent lithium iron phosphate batteries has increased dramatically. Efficiently and environmentally friendly recycling of the valuable materials in these spent batteries, achieving resource recycling, has become a critical issue that needs to be addressed in the current battery recycling field. Currently, the main method for reusing spent lithium iron phosphate batteries involves high-temperature heat treatment. While existing high-temperature heat treatment methods can decompose and recombine the active substances in the battery materials through high temperatures, the difficulty in precisely controlling reaction conditions (such as temperature and atmosphere) during the treatment process results in unstable quality and large performance fluctuations in the recycled materials, making it difficult to meet the raw material requirements for high-performance batteries.

[0003] In the current related technologies, the carbon thermal reduction regeneration of waste lithium iron phosphate batteries has the technical problem of unstable quality of the recycled materials. Summary of the Invention

[0004] The present application provides a carbon thermal reduction regeneration method for waste lithium iron phosphate batteries. The waste batteries are precisely disassembled through visual positioning technology to obtain positive electrode black powder materials, and oxidation treatment is performed in an air atmosphere to optimize the material composition. The precise ratio of lithium, iron, phosphorus source and carbon source is calculated based on the composition of the oxidation product. The raw materials are evenly mixed through a mixing device. Under nitrogen protection, a segmented temperature control strategy is used to perform carbon thermal reduction sintering on the raw materials. The temperature curve is controlled in real time through a PID controller and a temperature sensor device to ensure that the reaction path is controllable. These technical means solve the technical problem of unstable quality of recycled materials in the existing carbon thermal reduction regeneration of waste lithium iron phosphate batteries, and achieve the technical effect of high-quality preparation of recycled materials.

[0005] The present application provides a carbon thermal reduction regeneration method for waste lithium iron phosphate batteries, comprising: visually locating and disassembling and separating the waste lithium iron phosphate batteries to obtain a battery positive electrode black powder material, and placing the battery positive electrode black powder material in an air atmosphere heating furnace for oxidation treatment control to obtain a positive electrode oxidation product; calculating a raw material ratio based on the composition information of the positive electrode oxidation product to determine the raw material ratio and dosage, wherein the raw material ratio and dosage include a lithium source, an iron source, a phosphorus source and a carbon source reducing agent; placing the positive electrode oxidation product and the lithium source, iron source, phosphorus source and carbon source reducing agent into a mixing device according to the raw material ratio and dosage for mixing to obtain a raw material mixture; selecting a nitrogen atmosphere sintering furnace, the nitrogen atmosphere sintering furnace being equipped with a PID controller and a temperature sensing device, placing the raw material mixture into the nitrogen atmosphere sintering furnace according to a segmented temperature control sintering strategy for sintering carbon thermal reduction, and monitoring and regulating battery regeneration based on the PID controller and the temperature sensing device.

[0006] In a possible implementation, the battery positive electrode black powder material is obtained by performing the following processing: building a waste battery disassembly line, which includes a mechanical force disassembly device, a thermal field heating device and a visual recognition module; placing the waste lithium iron phosphate battery into the feed port of the waste battery disassembly line, and transporting it to the visual recognition module for positioning and identification to obtain the positive electrode sheet position information; transmitting the positive electrode sheet position information to the mechanical force disassembly device for disassembly and separation, and heating it according to a preset thermal field temperature through the thermal field heating device to obtain the battery positive electrode separation material; crushing and grading the battery positive electrode separation material, screening the particle size and collecting the impurities to obtain the battery positive electrode black powder material.

[0007] In a possible implementation, the positive electrode sheet position information is obtained by performing the following processing: performing posture adjustment and image acquisition on the waste lithium iron phosphate battery through the visual recognition module to obtain an appearance image of the waste battery; using a Gaussian filter to filter the appearance image of the waste battery to obtain a standard appearance image of the waste battery; extracting the convolution feature threshold of the lithium battery positive electrode sheet template, matching and segmenting the standard appearance image of the waste battery based on the convolution feature threshold to obtain the positive electrode sheet area; using the Canny operator to perform edge recognition and positioning marking on the positive electrode sheet area, and outputting the positive electrode sheet position information.

[0008] In a possible implementation, the positive electrode oxidation product is obtained by performing the following processing: the positive electrode oxidation process is stage-by-stage disassembly to obtain an oxidation heating stage, an oxidation insulation stage, and an oxidation cooling stage; the oxidation heating stage, the oxidation insulation stage, and the oxidation cooling stage are temperature-analyzed according to the battery oxidation treatment target to generate a heating stage curve, a insulation stage curve, and a cooling stage curve; based on the heating stage curve, the insulation stage curve, and the cooling stage curve, the air atmosphere heating furnace is controlled to perform oxidation treatment on the battery positive electrode black powder material to obtain the positive electrode oxidation product.

[0009] In a possible implementation, the raw material ratio and dosage are determined by performing the following processing: obtaining the lithium iron phosphorus element content based on the composition information of the positive electrode oxidation product; determining the target stoichiometric ratio based on the battery regeneration demand and material performance requirements; taking the absolute value of the difference between the lithium iron phosphorus element content and the target stoichiometric ratio as the lithium iron phosphorus element correction amount; and calculating the raw material ratio of the lithium source, iron source, phosphorus source and carbon source reducing agent based on the lithium iron phosphorus element correction amount to obtain the raw material ratio and dosage.

[0010] In a possible implementation, the raw material ratio and dosage are obtained by performing the following processing: determining the carbon source dosage according to the target stoichiometric ratio, and simultaneously obtaining the chemical formula information of the lithium source, iron source, and phosphorus source; calculating the raw material dosage of the chemical formula information of the lithium source, iron source, and phosphorus source based on the lithium iron phosphorus element correction amount to obtain the lithium iron phosphorus raw material dosage; calculating the raw material dosage of the carbon source reducing agent based on the carbon source dosage according to the carbon coating requirement to obtain the carbon raw material dosage, and determining the raw material ratio and dosage according to the lithium iron phosphorus raw material dosage and the carbon raw material dosage.

[0011] In a possible implementation, the raw material mixture is placed in the nitrogen atmosphere sintering furnace for sintering carbon thermal reduction according to the segmented temperature-controlled sintering strategy, and the following processing is performed: the segmented temperature-controlled sintering strategy is node-decomposed to determine the temperature-controlled sintering node set; the sintering parameters of the raw material mixture are analyzed based on the temperature-controlled sintering node set to obtain the node temperature-controlled sintering parameter set; based on the node temperature-controlled sintering parameter set, the raw material mixture is placed in the nitrogen atmosphere sintering furnace for sintering carbon thermal reduction.

[0012] In a possible implementation, the node temperature-controlled sintering parameter set is obtained and the following processing is performed: associated data mining is performed based on the temperature-controlled sintering node set to construct a temperature-controlled sintering node carbon thermal reduction data space; the composition information of the raw material mixture is used as a constraint parameter, and the carbon thermal reduction effect is optimized in the temperature-controlled sintering node carbon thermal reduction data space to determine the node temperature-controlled sintering parameter set.

[0013] In a possible implementation, the battery regeneration monitoring and control based on the PID controller and the temperature sensor device performs the following processing: collecting the sintering temperature data during the carbon thermal reduction process through the temperature sensor device; using the PID controller to control and analyze the node temperature control sintering parameter set and the sintering temperature data, determine the sintering parameter correction amount, and perform battery reduction and regeneration control through the sintering parameter correction amount.

[0014] In a possible implementation, the following processing is also performed: taking out the sintered product from the nitrogen atmosphere sintering furnace for sampling and testing to obtain battery regeneration quality parameters; and optimizing and correcting the node temperature control sintering parameter set based on the battery regeneration quality parameters.

[0015] The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries proposed in this application first visually locates and disassembles the waste lithium iron phosphate batteries to obtain battery positive electrode black powder material. The battery positive electrode black powder material is then placed in an air atmosphere heating furnace for oxidation treatment control to obtain a positive electrode oxidation product. Then, based on the composition information of the positive electrode oxidation product, a raw material ratio is calculated to determine the raw material ratio and amount. The raw material ratio and amount include a lithium source, an iron source, a phosphorus source, and a carbon source reducing agent. The positive electrode oxidation product and the lithium source, iron source, phosphorus source, and carbon source reducing agent are then placed in a mixing device and mixed according to the raw material ratio and amount to obtain a raw material mixture. Finally, a nitrogen atmosphere sintering furnace is selected. The nitrogen atmosphere sintering furnace is equipped with a PID controller and a temperature sensor device. The raw material mixture is placed in the nitrogen atmosphere sintering furnace according to a segmented temperature control sintering strategy for carbon thermal reduction. The battery regeneration is monitored and controlled based on the PID controller and temperature sensor device. The technical effect of high-quality preparation of recycled materials is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention are briefly introduced below. Flowcharts are used in this application to illustrate the operations performed by the methods according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in precise order. Instead, various steps may be processed in reverse order or simultaneously as needed. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0017] Figure 1 A schematic flow chart of the carbon thermal reduction regeneration method for waste lithium iron phosphate batteries provided in an embodiment of the present application.

[0018] Figure 2 This is a schematic diagram of the process for obtaining battery positive electrode black powder material in the carbon thermal reduction regeneration method of waste lithium iron phosphate batteries provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below.

[0020] In order to make the purpose, technical solutions and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limiting this application. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0021] In the following description, reference is made to “some embodiments” which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict. The terms “including” and “having” and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used herein are for the purpose of describing the embodiments of this application only.

[0022] The present invention provides a carbon thermal reduction regeneration method for waste lithium iron phosphate batteries. Figure 1 As shown, the method includes: Step S100: visually locate and disassemble the waste lithium iron phosphate battery to obtain the battery positive electrode black powder material, and place the battery positive electrode black powder material in an air atmosphere heating furnace for oxidation treatment control to obtain a positive electrode oxidation product.

[0023] Specifically, industrial-grade visual recognition equipment, such as high-resolution cameras and image processing software, is used to precisely locate used lithium iron phosphate batteries. The visual system uses a preset algorithm to identify the shape, size, and position of used lithium iron phosphate batteries, providing precise coordinate information for disassembly. Automated disassembly equipment, such as robotic arms and specialized disassembly tools, is used to precisely disassemble the battery casing and separate components such as the positive electrode, negative electrode, and electrolyte based on the positioning information provided by the visual system. Safety measures are implemented during the disassembly process to prevent battery short circuits or leakage. The separated battery positive electrode black powder material is placed in an air atmosphere heating furnace, and the positive electrode material is oxidized by precisely controlling the temperature and time. The heating furnace is equipped with a temperature controller and an atmosphere control system to ensure that the oxidation process is carried out under the set conditions.

[0024] For example, industrial-grade cameras (such as the Basler ace series) and image processing software (such as HALCON) use a predefined algorithm to identify the shape and position of spent lithium iron phosphate batteries, providing precise coordinate information for disassembly. A KUKA robotic arm equipped with a dedicated battery disassembly fixture uses the coordinate information provided by the vision system to precisely disassemble the battery casing and separate the positive electrode black powder. A muffle furnace (such as the Nabertherm LHT series) is used, with a temperature controller (such as a PID controller) set to an oxidation temperature of 300°C and an oxidation time of 2 hours to ensure sufficient oxidation of the positive electrode material.

[0025] like Figure 2 As shown, in a possible implementation, the battery positive electrode black powder material is obtained, and step S100 further includes step S110, setting up a waste battery disassembly line, and the waste battery disassembly line includes a mechanical disassembly device, a thermal field heating device, and a visual recognition module. Specifically, the mechanical disassembly device is a device used to physically disassemble the battery shell and internal components, such as a hydraulic shear (such as Amada's AP series), a robotic arm (such as ABB's IRB series), etc. The thermal field heating device is a device used to heat the battery to soften the adhesive or separate components, such as an infrared heating furnace (such as Carbolite's IR series), and the preset thermal field temperature is 150°C. The visual recognition module is a high-resolution camera (such as Basler's ace series) and an image processing system (such as HALCON) used to identify battery positions and components.

[0026] In step S120, the used lithium iron phosphate batteries are placed into the feed port of the used battery disassembly line and transported to the visual recognition module for positioning and identification, thereby obtaining the position information of the positive electrode sheets. Specifically, an automatic feeding conveyor is used to place the used lithium iron phosphate batteries into the feed port of the disassembly line and transport the batteries to the visual recognition module. A high-resolution camera and image processing software are used to locate and identify the batteries, and the position information of the positive electrode sheets is obtained. For example, a Basler ace series camera with a resolution of 1920×1080 is used, and HALCON software is used to identify the position of the positive electrode sheets and obtain coordinate information.

[0027] In step S130, the position information of the positive electrode sheet is transmitted to the mechanical disassembly device for disassembly and separation, and the thermal field heating device performs a heating treatment according to a preset thermal field temperature to obtain a battery positive electrode separation material. Specifically, according to the position information provided by the visual recognition module, the robotic arm disassembles the battery and separates the positive electrode sheet. The separated positive electrode sheet is heated to soften the binder. For example, an ABB IRB series robotic arm is used to accurately disassemble the battery according to the coordinate information provided by the HALCON software. A Carbolite IR series infrared heating furnace is used, with a preset temperature of 150°C and a heating time of 10 minutes to soften the binder.

[0028] In step S140, the battery positive electrode separated material is crushed, graded, and screened for particle size, and then removed and collected to obtain the battery positive electrode black powder material. Specifically, a jaw crusher (such as Metso's LT series) or a ball mill is used to crush the positive electrode sheets into powder, for example, to a particle size of less than 1 mm. A vibrating screen (such as Russell's Vibrasonic series) or an air classifier is used to grade the powder, for example, to a fine powder with a particle size of less than 0.1 mm. A magnetic separator (such as Eriez's ErieMag series) or an air classifier is used to remove impurities and collect the pure battery positive electrode black powder material. This implementation method utilizes a mechanical disassembly device, a thermal field heating device, and a visual recognition module to achieve efficient disassembly of used batteries, improving disassembly efficiency and accuracy. Grading, screening, and impurity removal ensure the particle size uniformity and purity of the battery positive electrode black powder material.

[0029] In one possible implementation, obtaining the positive electrode position information in step S120 further includes step S121, where the visual recognition module performs posture adjustment and image capture on the used lithium iron phosphate battery to obtain an image of the used battery's appearance. Specifically, a high-resolution industrial camera is mounted on a fixed bracket to ensure that the camera's field of view covers the entire battery. A rotating platform (such as a Thorlabs rotating platform with 360-degree rotation) is used to position the used lithium iron phosphate battery. The platform is driven by a motor and can precisely control the rotation angle. The used lithium iron phosphate battery is placed on the rotating platform, which is rotated by a motor to sequentially align different sides of the battery with the camera. For example, each 90-degree rotation of the rotating platform captures four images from different sides. Image processing software is used to monitor the images captured by the camera in real time. When the battery's positive electrode is fully within its field of view, the platform's rotation is stopped. The camera captures an image of the battery's positive electrode at an optimal angle, ensuring that the image is clear and centered. The captured image is saved in high-resolution JPEG or PNG format for subsequent processing.

[0030] Step S122: Filter the used battery appearance image using a Gaussian filter to obtain a standard used battery appearance image. Specifically, use image processing software (such as OpenCV or MATLAB) to load the collected used battery appearance image. Set the Gaussian filter parameters in the software with a kernel size of 5×5 and a standard deviation of 1.5. Apply a Gaussian filter to smooth the image to remove noise and high-frequency interference. For example, use the cv2.GaussianBlur function in OpenCV to perform a Gaussian filter on the image. Save the filtered image to ensure that the image is clear and noise is effectively removed.

[0031] Step S123, extract the convolution feature threshold of the lithium battery positive electrode template, match and segment the standard waste battery appearance image based on the convolution feature threshold, and obtain the positive electrode area. Specifically, use a pre-trained convolutional neural network (CNN) model (such as ResNet or VGG) to load the convolution feature threshold of the lithium battery positive electrode template. Use image processing software (such as OpenCV) to load the filtered image. Input the filtered image into the CNN model to extract the convolution features of the image. Use the feature map output by the model to match the convolution feature threshold of the lithium battery positive electrode template. Use OpenCV's template matching function (such as cv2.matchTemplate) in combination with the convolution feature threshold to match and segment the image. Extract the matched positive electrode area and generate a mask image of the positive electrode.

[0032] Step S124, use the Canny operator to perform edge identification and positioning marking on the positive electrode sheet area, and output the positive electrode sheet position information. Specifically, use image processing software (such as OpenCV) to load the positive electrode sheet mask image. Use the Canny edge detection algorithm, set the low threshold to 50 and the high threshold to 150, and perform edge detection on the positive electrode sheet mask image. Extract the edge contour of the positive electrode sheet and generate an edge image. Use OpenCV's contour detection function (such as cv2.findContours) to extract the contour in the edge image. Calculate the geometric center of the contour and generate the position coordinate information of the positive electrode sheet. Output the position coordinate information to the control system for subsequent disassembly operations. This implementation method achieves accurate marking of the positive electrode sheet position through Gaussian filter processing, convolution feature threshold and template matching technology, and the application of the Canny operator, providing accurate guidance for subsequent disassembly and processing.

[0033] In one possible implementation, obtaining the positive electrode oxidation product in step S100 further includes step S150, which breaks down the positive electrode oxidation process into stages, including an oxidation heating stage, an oxidation holding stage, and an oxidation cooling stage. Specifically, an air atmosphere heating furnace (such as Nabertherm's LHT series) equipped with a temperature controller (such as a PID controller) and a thermocouple temperature sensor is used. A data acquisition system (such as an NI data acquisition card and LabVIEW software) is used to record and analyze temperature data. Based on the battery oxidation treatment objectives, the oxidation process is divided into three stages: an oxidation heating stage, an oxidation holding stage, and an oxidation cooling stage. Specific parameters are set for each stage. For example, the oxidation heating stage is to increase the temperature from room temperature (25°C) to the target temperature (300°C); the oxidation holding stage is to maintain the temperature at 300°C for 2 hours; and the oxidation cooling stage is to naturally cool to room temperature.

[0034] In step S160, temperature analysis is performed on the oxidation heating stage, oxidation holding stage, and oxidation cooling stage according to the battery oxidation treatment target to generate a heating stage curve, a holding stage curve, and a cooling stage curve. Specifically, temperature analysis software (such as MATLAB or LabVIEW) is used to analyze the set battery oxidation treatment target. Based on the battery oxidation treatment target, the oxidation heating stage, oxidation holding stage, and oxidation cooling stage are analyzed in detail to determine the specific temperature curve for each stage. For example, the heating stage curve is from 25°C to 300°C at a heating rate of 5°C / min. The holding stage curve is maintained at 300°C for 2 hours. The cooling stage curve is naturally cooled to room temperature at a cooling rate of 2°C / min.

[0035] Step S170, based on the heating stage curve, the heat preservation stage curve and the cooling stage curve, the air atmosphere heating furnace is controlled to perform oxidation treatment on the battery positive electrode black powder material to obtain the positive electrode oxidation product. Specifically, according to the generated heating stage curve, the heat preservation stage curve and the cooling stage curve, the air atmosphere heating furnace is controlled to perform oxidation treatment on the battery positive electrode black powder material. LabVIEW software is used to record the temperature changes during the entire oxidation process to ensure the accuracy and consistency of the oxidation treatment. This implementation method divides the oxidation treatment into three stages: heating, heat preservation and cooling. Each stage has clear temperature and time control, which improves the effect and efficiency of the oxidation treatment.

[0036] Step S200 , performing raw material ratio calculation based on the composition information of the positive electrode oxidation product to determine the raw material ratio and amount, wherein the raw material ratio and amount include a lithium source, an iron source, a phosphorus source, and a carbon source reducing agent.

[0037] Specifically, the composition of the cathode oxidation product is analyzed using equipment such as an X-ray fluorescence spectrometer (XRF) or an inductively coupled plasma mass spectrometer (ICP-MS) to determine the content of elements such as lithium, iron, and phosphorus. Based on this compositional analysis and the stoichiometric ratio of the target lithium iron phosphate material, the dosages of the lithium, iron, phosphorus, and carbon source reducing agents are calculated using dedicated ratio calculation software (such as MATLAB or Excel macros). A high-precision electronic balance (such as the METTLER TOLEDO XP series) is used to accurately weigh the raw materials according to the calculated results to ensure accurate ratios.

[0038] For example, an XRF instrument (such as the Bruker S4 PIONEER) is used to analyze the composition of the cathode oxidation product to determine the content of elements such as lithium, iron, and phosphorus. A MATLAB program is developed to input the composition analysis results and calculate the specific amounts of the lithium source (such as lithium carbonate), iron source (such as iron oxide), phosphorus source (such as ammonium dihydrogen phosphate), and carbon source reducing agent (such as graphite powder). A Mettler-Toledo XP205 electronic balance is used to accurately weigh the raw materials to ensure accurate mixing ratios.

[0039] In one possible implementation, determining the raw material ratio and amount in step S200 further includes step S210, where the lithium, iron, and phosphorus content is determined based on the compositional information of the positive electrode oxidation product. Specifically, a high-precision electronic balance (such as the XP series from Mettler-Toledo) is used to weigh the sample. An appropriate amount of sample (e.g., 0.1 g) is placed in a sample cup for composition analysis. Analysis is performed using an X-ray fluorescence spectrometer (XRF) or an inductively coupled plasma mass spectrometer (ICP-MS) according to standard operating procedures to determine the content of lithium (Li), iron (Fe), and phosphorus (P). For example, the analysis results show a Li content of 1.5%, an Fe content of 15.0%, and a P content of 3.0%.

[0040] Step S220 determines the target stoichiometric ratio based on the battery regeneration needs and material performance requirements. Specifically, based on the specific battery regeneration objectives, such as the capacity, cycle life, and charge-discharge performance of the regenerated battery, as well as the performance characteristics of the target lithium iron phosphate material, the appropriate stoichiometric ratio of lithium, iron, and phosphorus is determined by consulting relevant information or conducting experimental research. For example, for high-performance regenerated lithium iron phosphate batteries, in order to achieve high capacity and good cycle stability, the stoichiometric ratio of lithium, iron, and phosphorus is determined to be Li:Fe:P = 1:1:1 after research or reference to industry standards.

[0041] Step S230: The absolute value of the difference between the lithium iron phosphorus content and the target stoichiometric ratio is used as the lithium iron phosphorus correction amount. Specifically, the actual content of lithium, iron, and phosphorus in the positive electrode oxidation product obtained in step S210 is compared with the target stoichiometric ratio determined in step S220, and the difference between the actual content of lithium, iron, and phosphorus and the corresponding element ratio in the target stoichiometric ratio is calculated. The absolute value of these differences is then taken to obtain the correction amount of lithium, iron, and phosphorus. The mass percentage must first be converted to moles before the difference from the target stoichiometric ratio is calculated.

[0042] Step S240 calculates the raw material ratios for the lithium source, iron source, phosphorus source, and carbon source reducing agent based on the corrected lithium, iron, and phosphorus amounts to determine the raw material ratios. Specifically, the calculation is performed using dedicated ratio calculation software (such as MATLAB or an Excel macro) based on the corrected lithium, iron, and phosphorus amounts obtained in step S230, the form of each element in the raw materials (e.g., the lithium source may be lithium carbonate, the iron source may be iron oxide, the phosphorus source may be ammonium dihydrogen phosphate, etc.), and the required amount of the carbon source reducing agent (e.g., graphite powder). The calculation takes into account factors such as the purity of each element in the raw materials and the conversion rate during the reaction, thereby accurately determining the specific ratios and amounts of the lithium source, iron source, phosphorus source, and carbon source reducing agent.

[0043] For example, a ratio calculation program can be written using MATLAB, with input information such as the actual content of lithium, iron, and phosphorus, the target stoichiometric ratio, and the purity of each element in the raw materials. Based on the correction amounts of lithium, iron, and phosphorus, the program calculates the amount of raw materials required to achieve the target stoichiometric ratio. This implementation method ensures that the content of each element in the recycled battery material meets the target stoichiometric ratio through precise raw material ratio calculation, thereby improving the quality and performance of the recycled battery material and ensuring that the regenerated battery meets the needs of battery regeneration and material performance requirements.

[0044] In one possible implementation, obtaining the raw material ratio and dosage, step S240 further includes step S241, determining the carbon source dosage based on the target stoichiometric ratio, and simultaneously obtaining the chemical formula information of the lithium source, iron source, and phosphorus source. Specifically, during the regeneration process, a reducing agent is required to reduce high-valent metal ions to low-valent states. The amount of reducing agent is calculated based on the chemical reaction equation and the degree of oxidation of the raw materials. For example, if high-valent metal ions are present in the lithium source, iron source, or phosphorus source, a reducing agent (such as a carbon source) is required to reduce them to the desired low-valent state to form the target compound (such as LiFePO4). The specific amount of reducing agent required needs to be determined based on the stoichiometric relationship of the chemical reaction and experimental conditions to ensure that the reaction proceeds completely. Determining the specific chemical formula of the lithium source, iron source, and phosphorus source, such as Li2CO3, Fe2O3, NH4H2PO4, etc., provides the basis for subsequent raw material dosage calculations.

[0045] Step S242 calculates the raw material usage based on the chemical formula information of the lithium source, iron source, and phosphorus source, based on the lithium iron phosphorus element correction amount, to obtain the lithium iron phosphorus raw material usage. Specifically, the actual amount of raw materials required to be replenished is calculated based on the lithium, iron, and phosphorus element correction amounts obtained in step S230, combined with the chemical formula information and purity of the lithium source, iron source, and phosphorus source.

[0046] In step S243, the raw material amount of the carbon source reducing agent is calculated based on the carbon source amount according to the carbon coating requirements to obtain the carbon raw material amount, and the raw material ratio amount is determined based on the lithium iron phosphorus raw material amount and the carbon raw material amount. Specifically, carbon coating is an important means to improve the conductivity and stability of battery materials. The amount of additional carbon source to be added is determined based on the carbon coating requirements (such as the thickness and uniformity of the coating layer). The amount of carbon coating agent is determined based on experimental data or literature reports to ensure that the material has good electrochemical properties. The final carbon raw material amount is the sum of the carbon used for reduction and the carbon used for coating. The lithium, iron, and phosphorus raw material amounts obtained in step S242 are integrated with the carbon raw material amount to determine the final raw material ratio amount, ensuring that the ratio between the raw materials meets the preparation requirements of the recycled battery material. This implementation method accurately determines the total amount of carbon source based on the target stoichiometric ratio and carbon coating requirements, and rationally allocates the amount of the reducing agent portion and the carbon coating portion, ensuring the performance of the recycled material.

[0047] Step S300: putting the positive electrode oxidation product and the lithium source, iron source, phosphorus source and carbon source reducing agent into a mixing device according to the raw material ratio and amount, and mixing them to obtain a raw material mixture.

[0048] Specifically, using a high-energy ball mill (equipment that mixes raw materials through ball milling, such as the Fritsch Pulverisette 7) or a planetary ball mill, the cathode oxidation product and the raw materials are placed in a milling jar and uniformly mixed through ball milling. The mill's parameters, such as speed, milling time, and ball-to-material ratio, are adjusted to ensure uniform mixing. A small amount of solvent, such as ethanol, can be added during the milling process to prevent the raw materials from clumping.

[0049] For example, a Fritsch Pulverisette 7 high-energy ball mill is used to place the positive electrode oxidation product and various raw materials into a ball milling jar, set the rotation speed to 500 rpm, the ball milling time to 12 hours, the ball-to-material ratio to 10:1, and add an appropriate amount of ethanol as a dispersant.

[0050] In step S400, a nitrogen atmosphere sintering furnace is selected, and the nitrogen atmosphere sintering furnace is equipped with a PID controller and a temperature sensing device. The raw material mixture is placed in the nitrogen atmosphere sintering furnace for sintering and carbon thermal reduction according to a segmented temperature-controlled sintering strategy, and battery regeneration monitoring and control are performed based on the PID controller and the temperature sensing device.

[0051] Specifically, a nitrogen atmosphere sintering furnace is a device that performs sintering in a nitrogen atmosphere to prevent oxidation and control the sintering atmosphere. A dedicated nitrogen atmosphere sintering furnace (such as Lenton's LH series) is equipped with a PID controller (an automatic control device that uses proportional, integral, and differential control algorithms to achieve precise temperature control) and a temperature sensor (such as a K-type thermocouple for real-time temperature monitoring) to ensure that the sintering process is carried out under precisely controlled temperature and atmosphere conditions. Multiple sintering temperature and time stages are set based on the characteristics of the raw material mixture, such as a pre-sintering stage (300°C, 2 hours), a carbothermal reduction stage (700°C, 4 hours), and a cooling stage (natural cooling). The PID controller and temperature sensor monitor and control the temperature in real time to ensure a stable and consistent sintering process. A nitrogen flow controller (such as Bronkhorst's EL-FLOW series) ensures a stable nitrogen flow during sintering to prevent oxidation reactions.

[0052] In one possible implementation, the raw material mixture is placed in the nitrogen atmosphere sintering furnace for sintering and carbothermal reduction according to a segmented temperature-controlled sintering strategy. Step S400 further includes step S410 of node-decomposing the segmented temperature-controlled sintering strategy to determine a set of temperature-controlled sintering nodes. Specifically, segmented temperature-controlled sintering is a method for controlling the reaction process by setting different sintering conditions (such as temperature, time, and atmosphere) in different temperature segments. This method ensures a gradual reaction and avoids incomplete reactions or unstable product quality caused by excessively high or low temperatures. The entire sintering process is broken down into multiple temperature nodes (or temperature segments), each corresponding to a specific temperature range and hold time. For example, the sintering process can be divided into a low-temperature segment, a medium-temperature segment, and a high-temperature segment, each corresponding to different reaction requirements. The specific temperature value and hold time for each temperature node are determined based on reaction kinetics and thermodynamic analysis. For example, the low-temperature segment is used to remove volatile matter and moisture from the raw materials, the medium-temperature segment is used to promote the initial chemical reaction, and the high-temperature segment is used to complete the final sintering and carbothermal reduction reactions.

[0053] Step S420, based on the temperature-controlled sintering node set, the sintering parameters of the raw material mixture are analyzed to obtain a node temperature-controlled sintering parameter set. Specifically, according to the temperature-controlled sintering node set determined in step S410, a detailed sintering parameter analysis is performed on each temperature node. The analyzed parameters include temperature, holding time, heating rate, cooling rate, nitrogen flow rate, etc. The sintering parameters of each temperature node are integrated into a complete node temperature-controlled sintering parameter set. For example, a low temperature section (100-300°C, holding time 2 hours, heating rate 5°C / min), a medium temperature section (300-600°C, holding time 4 hours, heating rate 3°C / min), and a high temperature section (600-800°C, holding time 6 hours, heating rate 2°C / min).

[0054] Step S430, based on the node temperature-controlled sintering parameter set, the raw material mixture is placed in the nitrogen atmosphere sintering furnace for sintering and carbon thermal reduction. Specifically, according to the node temperature-controlled sintering parameter set obtained in step S420, the raw material mixture is placed in a nitrogen atmosphere sintering furnace. According to the set temperature nodes and parameters, sintering and carbon thermal reduction reactions are carried out step by step. During the sintering process, the temperature, atmosphere and other parameters are monitored in real time to ensure that they meet the preset node temperature-controlled sintering parameter set. If necessary, the parameters are fine-tuned according to the actual situation to ensure the smooth progress of the reaction and the quality of the product. This implementation method can effectively control the reaction process and improve the purity and uniformity of recycled battery materials through a segmented temperature-controlled sintering strategy, thereby providing a good foundation for its application in batteries.

[0055] In one possible implementation, the node temperature-controlled sintering parameter set is obtained, and step S420 further includes step S421, performing associated data mining based on the temperature-controlled sintering node set to construct a temperature-controlled sintering node carbon thermal reduction data space. Specifically, historical data or experimental data related to the segmented temperature-controlled sintering process are collected, including reaction rate, product purity, structural characteristics, etc. at different temperature nodes. Data mining techniques (such as cluster analysis or association rule mining algorithms, etc.) are used to analyze these data to find the correlation between temperature nodes and reaction effects. Based on the mined correlation, a multi-dimensional "temperature-controlled sintering node carbon thermal reduction data space" is constructed. This data space can represent the influence of parameters such as different temperature nodes, holding time, heating rate, etc. on the carbon thermal reduction effect.

[0056] In step S422, the composition of the raw material mixture is used as a constraint parameter to optimize the carbothermic reduction effect within the temperature-controlled sintering node carbothermic reduction data space, thereby determining the node temperature-controlled sintering parameter set. Specifically, the composition of the raw material mixture (such as the lithium, iron, and phosphorus content, and the type and amount of carbon source) is used as a constraint parameter. These constraint parameters limit the search space of the optimization process, ensuring that the optimization results meet the actual raw material characteristics and requirements. Within the constructed temperature-controlled sintering node carbothermic reduction data space, an optimization algorithm (such as a genetic algorithm or particle swarm optimization) is used to optimize the carbothermic reduction effect. Optimization objectives may include performance indicators such as product purity, crystallinity, and conductivity. Through the optimization process, the node temperature-controlled sintering parameter set that achieves the optimal carbothermic reduction effect under the given raw material composition and constraints is determined. This parameter set includes the specific temperature value, hold time, and heating rate for each temperature node. This implementation approach, combining data mining and optimization techniques, provides scientific and reasonable parameter settings for the staged temperature-controlled sintering process, thereby improving the quality and performance of recycled battery materials.

[0057] In one possible implementation, the battery regeneration monitoring and control is performed based on the PID controller and the temperature sensing device, and step S400 further includes step S440, in which the sintering temperature data during the carbon thermal reduction process is collected by the temperature sensing device. Specifically, temperature sensing devices (such as thermocouples, infrared thermometers, etc.) are reasonably arranged inside the nitrogen atmosphere sintering furnace to ensure that the temperature data during the sintering process can be fully and accurately collected. The sensing device should be installed in a key position that can reflect the overall sintering temperature changes to avoid the impact of local temperature anomalies on data collection. During the sintering process, the temperature sensing device collects sintering temperature data in real time and transmits it to the control system. The collected data includes key information such as the actual temperature value of each temperature node and the temperature change rate. The collected sintering temperature data is preprocessed, such as filtering and denoising, to improve the accuracy and reliability of the data. The preprocessed data is used for subsequent control and analysis.

[0058] In step S450, a PID controller is used to control and analyze the node temperature-controlled sintering parameter set and the sintering temperature data, determine sintering parameter corrections, and use these corrections to control battery reduction and regeneration. Specifically, a PID controller (proportional-integral-differential controller) is an automatic control system that controls the battery based on the deviation between the set value (node temperature-controlled sintering parameter set) and the actual value (sintering temperature data). The PID controller achieves precise temperature control by adjusting the proportional, integral, and differential parameters. The collected sintering temperature data is compared with the preset node temperature-controlled sintering parameter set to calculate the deviation. The PID controller then controls and analyzes the deviation to determine the required sintering parameter corrections (such as temperature corrections and time corrections). Based on the determined sintering parameter corrections, the temperature, time, and other parameters of the nitrogen atmosphere sintering furnace are adjusted in real time. The adjusted parameters are used in the subsequent sintering process to ensure that the sintering process is carried out according to preset requirements. During the sintering process, the sintering temperature data is continuously monitored, and feedback adjustments are made based on actual conditions. By continuously adjusting the sintering parameters, the sintering process is ensured to be stable and efficient, ultimately yielding high-quality recycled battery materials. This approach uses a PID controller to regulate the sintering process in real time, ensuring that the sintering temperature is precisely controlled within a preset range, thereby improving the quality and performance of the recycled battery materials.

[0059] In one possible implementation, the method further includes: taking out the sintered product from the nitrogen atmosphere sintering furnace for sampling and testing to obtain battery regeneration quality parameters; and optimizing and correcting the node temperature control sintering parameter set based on the battery regeneration quality parameters.

[0060] Specifically, after sintering is completed, the nitrogen atmosphere sintering furnace is cooled to a safe temperature (e.g., room temperature or below 100°C). The furnace door is opened under a nitrogen atmosphere to prevent product oxidation. Samples are taken from various locations within the furnace (e.g., the center and edges) using clean tools (e.g., ceramic tweezers) to ensure representative samples. The samples are divided into multiple sections for different testing tasks. The product crystal structure is analyzed using X-ray diffraction (XRD) to ensure the correct crystal structure of the resulting lithium iron phosphate material. Scanning electron microscopy (SEM) is used to observe particle morphology and size distribution to assess the uniformity and integrity of the carbon coating. Elemental composition and impurity content are analyzed using inductively coupled plasma mass spectrometry (ICP-MS) or energy dispersive spectroscopy (EDS). The product is fabricated into electrode sheets and assembled into button-type batteries for testing of charge-discharge capacity, cycling stability, and rate performance. The test results are summarized as battery regeneration quality parameters, including crystallinity, impurity content, initial charge-discharge efficiency, and capacity retention after 50 cycles.

[0061] Correlate battery regeneration quality parameters with sintering parameters (such as node temperatures, holding time, and heating rate). For example, insufficient product crystallinity may be due to a short holding time or low temperature in the high-temperature stage. Excessive impurity content may indicate incomplete volatile removal in the low-temperature stage or uneven carbon coating in the high-temperature stage. Based on crystallinity requirements, appropriately increase the high-temperature stage temperature (e.g., from 750°C to 800°C) or extend the holding time (e.g., from 6 hours to 8 hours). If particle agglomeration is severe, reduce the heating rate in the medium-temperature stage (e.g., from 3°C / min to 2°C / min) to promote a uniform reaction. Consider the carbon coating effect (e.g., analyzing the graphitization of the carbon layer through Raman spectroscopy), and adjust the carbon source ratio (e.g., increasing the glucose dosage by 5%-10%). Apply the optimized parameter set to the next sintering batch, repeating the sampling and testing process to verify the improvement. Through multiple rounds of iteration, the optimal parameter combination is gradually approached until the quality parameters meet the preset standards (such as initial efficiency ≥90%, capacity retention ≥85% after 100 cycles). This implementation method further improves the consistency and performance of recycled battery materials through post-sintering product testing and parameter optimization.

[0062] The embodiment of the present application uses visual positioning technology to accurately disassemble waste batteries, obtain positive electrode black powder materials, and perform oxidation treatment in an air atmosphere to optimize the material composition. The precise ratio of lithium, iron, phosphorus source and carbon source is calculated based on the composition of the oxidation product, and the raw materials are evenly mixed through a mixing device. Under nitrogen protection, a segmented temperature control strategy is used to perform carbon thermal reduction sintering on the raw materials. The temperature curve is controlled in real time by a PID controller and a temperature sensor device to ensure that the reaction path is controllable. These technical means solve the technical problem of unstable quality of recycled materials in the existing carbon thermal reduction regeneration of waste lithium iron phosphate batteries, and achieve the technical effect of high-quality preparation of recycled materials.

[0063] The above specific embodiments do not constitute a limitation to the scope of protection of this application. It should be understood by those skilled in the art that various modifications, combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of this application should be included in the scope of protection of this application. In some cases, the actions or steps recorded in this application can be performed in an order different from that in the embodiments and can still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A carbon thermal reduction regeneration method for waste lithium iron phosphate batteries, characterized in that: The method comprises: Visually locate and disassemble waste lithium iron phosphate batteries to obtain battery positive electrode black powder material, and place the battery positive electrode black powder material into an air atmosphere heating furnace for controlled oxidation treatment to obtain positive electrode oxidation products; Calculating a raw material ratio based on the composition information of the positive electrode oxidation product to determine the raw material ratio and amount, wherein the raw material ratio and amount include a lithium source, an iron source, a phosphorus source, and a carbon source reducing agent; The positive electrode oxidation product and the lithium source, iron source, phosphorus source and carbon source reducing agent are placed in a mixing device according to the raw material ratio and amount, and mixed to obtain a raw material mixture; A nitrogen atmosphere sintering furnace is selected, and the nitrogen atmosphere sintering furnace is equipped with a PID controller and a temperature sensing device. The raw material mixture is placed in the nitrogen atmosphere sintering furnace for sintering carbon thermal reduction according to a segmented temperature-controlled sintering strategy, and battery regeneration monitoring and control are performed based on the PID controller and the temperature sensing device.

2. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 1, characterized in that: The method for obtaining the battery positive electrode black powder material comprises: Building a waste battery disassembly line, which includes a mechanical disassembly device, a thermal field heating device, and a visual recognition module; The waste lithium iron phosphate battery is placed in the feed port of the waste battery disassembly line and transported to the visual recognition module for positioning and identification to obtain the position information of the positive electrode sheet; Transmitting the positive electrode sheet position information to the mechanical force disassembly device for disassembly and separation, and performing heating treatment according to a preset thermal field temperature by the thermal field heating device to obtain a battery positive electrode separation material; The battery positive electrode separation material is crushed and classified, particle size screened, and impurity removed and collected to obtain the battery positive electrode black powder material.

3. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 2, characterized in that: The obtaining of the positive electrode position information includes: Performing posture adjustment and image acquisition on the waste lithium iron phosphate battery through the visual recognition module to obtain an appearance image of the waste battery; Using a Gaussian filter to filter the waste battery appearance image to obtain a standard waste battery appearance image; Extracting a convolution feature threshold of a lithium battery positive electrode template, and performing matching and segmentation on the standard waste battery appearance image based on the convolution feature threshold to obtain a positive electrode region; The Canny operator is used to perform edge recognition and positioning marking on the positive electrode area, and the positive electrode position information is output.

4. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 1, characterized in that: The obtaining of the positive electrode oxidation product comprises: The positive electrode oxidation process is disassembled into stages, including oxidation heating stage, oxidation heat preservation stage and oxidation cooling stage; Perform temperature analysis on the oxidation heating stage, oxidation heat preservation stage and oxidation cooling stage according to the battery oxidation treatment target, and generate a heating stage curve, a heat preservation stage curve and a cooling stage curve; Based on the heating stage curve, the heat preservation stage curve and the cooling stage curve, the air atmosphere heating furnace is controlled to perform oxidation treatment on the battery positive electrode black powder material to obtain the positive electrode oxidation product.

5. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 1, characterized in that: Determining the raw material ratio and dosage includes: Obtaining the lithium iron phosphorus element content according to the composition information of the positive electrode oxidation product; Determine the target stoichiometric ratio based on battery regeneration needs and material performance requirements; The absolute value of the difference between the lithium iron phosphorus content and the target stoichiometric ratio is used as the lithium iron phosphorus correction amount; The raw material ratio of the lithium source, iron source, phosphorus source and carbon source reducing agent is calculated based on the lithium iron phosphorus element correction amount to obtain the raw material ratio usage.

6. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 5, characterized in that: The method of obtaining the raw material ratio and dosage comprises: Determining the amount of the carbon source based on the target stoichiometric ratio, and simultaneously obtaining chemical formula information of the lithium source, iron source, and phosphorus source; Calculating the raw material usage of the lithium source, iron source, and phosphorus source based on the lithium iron phosphorus element correction amount to obtain the lithium iron phosphorus raw material usage; The raw material dosage of the carbon source reducing agent is calculated based on the carbon source dosage according to the carbon coating requirement to obtain the carbon raw material dosage, and the raw material ratio dosage is determined according to the lithium iron phosphorus raw material dosage and the carbon raw material dosage.

7. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 1, characterized in that: The step of placing the raw material mixture into the nitrogen atmosphere sintering furnace for sintering and carbon thermal reduction according to the staged temperature controlled sintering strategy includes: Decomposing the segmented temperature-controlled sintering strategy into nodes to determine a temperature-controlled sintering node set; performing sintering parameter analysis on the raw material mixture based on the temperature-controlled sintering node set to obtain a node temperature-controlled sintering parameter set; The raw material mixture is placed in the nitrogen atmosphere sintering furnace for sintering and carbon thermal reduction based on the node temperature controlled sintering parameter set.

8. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 7, characterized in that: The obtaining of the node temperature-controlled sintering parameter set includes: Performing associated data mining based on the temperature-controlled sintering node set to construct a carbon thermal reduction data space for the temperature-controlled sintering nodes; The composition information of the raw material mixture is used as a constraint parameter, and the carbothermic reduction effect is optimized in the carbothermic reduction data space of the temperature-controlled sintering node to determine the temperature-controlled sintering parameter set of the node.

9. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 8, characterized in that: The battery regeneration monitoring and control based on the PID controller and the temperature sensor device includes: collecting sintering temperature data during the carbothermal reduction process by means of the temperature sensing device; A PID controller is used to regulate and analyze the node temperature-controlled sintering parameter set and the sintering temperature data, determine a sintering parameter correction amount, and perform battery reduction and regeneration regulation based on the sintering parameter correction amount.

10. The carbon thermal reduction regeneration method for waste lithium iron phosphate batteries according to claim 9, characterized in that: The method further comprises: Taking out the sintered product from the nitrogen atmosphere sintering furnace for sampling and testing to obtain battery regeneration quality parameters; The node temperature-controlled sintering parameter set is optimized and corrected based on the battery regeneration quality parameter.

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