High-nickel NCM ternary positive electrode material and preparation method thereof

Abstract

The invention provides a preparation method of a high-nickel NCM ternary positive electrode material, and belongs to the technical field of battery materials, and the preparation method comprises the following steps: adding a complexing agent into a nickel-cobalt-manganese hydroxide precursor, a lithium salt and a mixed alkali solution, and carrying out a stirring reaction to form a uniformly mixed solution; on the basis of the uniformly mixed solution, the growth rate and morphology of the crystal are controlled by adjusting the PH value, so that the surface structure stability is improved; and carrying out heat treatment on the surface-modified product in a nitrogen protection atmosphere to obtain the high-nickel ternary material, thereby ensuring good structural integrity and cycle performance. Through the scheme of the invention, the problems of unstable surface structure and poor cycle performance of the high-nickel NCM ternary positive electrode material in the preparation process can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of battery materials, and in particular to a high-nickel NCM ternary positive electrode material and a preparation method thereof. Background Art

[0002] High nickel NCM (Nickel-Cobalt-Manganese) ternary positive electrode material is one of the positive electrode materials with higher energy density in the field of lithium-ion batteries. It usually refers to nickel-cobalt-manganese ternary composite oxides containing a higher proportion of nickel (e.g., 70%-90% nickel content). This material provides higher specific capacity through its chemical composition and helps to improve the overall electrochemical performance of lithium batteries. The general process for preparing such materials includes multiple steps such as mixing raw materials, dissolution, precipitation reaction, and high-temperature calcination. However, this process often faces a prominent problem, that is, the surface structure instability of high nickel NCM ternary positive electrode materials during their production stage and the subsequent poor cycle performance caused by this. Specifically, it is easy to form positions rich in defects such as metal oxides or oxygen vacancies on the surface of the material, which in turn affects the stability of the electrode material and the kinetics of lithium ion insertion-deinsertion, ultimately leading to a shortened battery cycle life and a decrease in overall performance. Therefore, in the process of developing and preparing such high-nickel materials, certain measures need to be taken to improve their structural stability and optimize the cycle efficiency of lithium-ion batteries. For example, improving the comprehensive performance indicators of the material itself through surface coating protection technology or setting other specific process conditions is the key to the research. Summary of the invention

[0003] In view of this, the embodiments of the present disclosure provide a high-nickel NCM ternary positive electrode material and a preparation method thereof to solve the problems existing in the prior art.

[0004] A method for preparing a high-nickel NCM ternary positive electrode material comprises the following steps:

[0005] S101, adding a complexing agent to a nickel-cobalt-manganese hydroxide precursor, a lithium salt and a mixed alkali solution, and stirring to react to form a uniform mixed solution;

[0006] S102, controlling the crystal growth rate and morphology by adjusting the pH value on the basis of the uniformly mixed solution to improve the surface structure stability;

[0007] S103, heat treating the surface-modified product under a nitrogen atmosphere to obtain a high-nickel ternary material, thereby ensuring good structural integrity and cycle performance.

[0008] Preferably, the surface-modified product is subjected to heat treatment under a nitrogen atmosphere, comprising:

[0009] S201, controlling the nitrogen flow rate to remain stable within X liters / minute, where X ranges from 5 to 10;

[0010] S202, setting a heating temperature Y degrees Celsius, selected within the range of 200 to 600 degrees Celsius;

[0011] S203, start the timer Z when the temperature Y is stable, and ensure that Z is within the time range of 8 hours to 24 hours;

[0012] S204, if the temperature Y is lower than 450 degrees Celsius, increase the processing time Z until the condition T = Y × Z ≥ 108000°C·min is met to ensure good structural integrity.

[0013] Further, controlling the nitrogen flow rate to X liters / minute to maintain stability includes:

[0014] S301, preheating the nitrogen introduced into the pipe to U degrees Celsius to remove water vapor inside the pipe, and U is preset to be between 100 and 250 degrees Celsius;

[0015] S302, open the gas supply valve V and observe the flow meter reading to confirm the actual inflow gas flow rate, and set V to maintain the flow rate X liters / minute in the target range of 5 to 10;

[0016] S303, adjusting the nitrogen pressure reducing valve W, and continuously fine-tuning until the error △X between the actual measured nitrogen flow rate and the predetermined flow rate X liters / minute is less than 1 liter / minute;

[0017] S304, when measuring the flow rate, if |△X|>5, repeat the above operation until the condition of △X≤0.5 is satisfied, so that the airflow is stable and uniform.

[0018] Further, opening the gas supply valve V and observing the flow meter reading to confirm that the actual inflow gas flow rate is set to be within the target range at a flow rate of X liters / minute includes:

[0019] S401, adjusting the gas supply pressure regulating device S to a predetermined position P degrees Celsius, and setting the P range to be between 1 and 2 MPa;

[0020] S402, visually check the flow meter to confirm whether the measured value Q of the inflowing nitrogen is equal to X, and the error △Q is required to satisfy the condition |△Q|=|QX| is less than 1 liter / minute;

[0021] S403, if the measured nitrogen flow rate does not meet the standard of Q=X, that is, △Q>5, adjust Q by changing the state of the regulating valve so that the deviation △Q≤0.5;

[0022] S404, if the deviation △Q still exceeds the allowable threshold, the valve is repeatedly adjusted until the deviation is less than or equal to the given standard.

[0023] Further, if the measured nitrogen flow rate does not meet the standard of Q = X, adjust the flow rate by changing the state of the regulating valve until it meets the standard, specifically including:

[0024] S501. Initially, set the opening and closing ratio of the regulating valve to N%, where the N range is between 50% and 80%, and start supplying gas;

[0025] S502. After measuring the inflow rate Z liters per minute, if Z < X, increase the opening and closing ratio by the value of ΔN to ensure that Z ≥ X under the condition of N = N + ΔN;

[0026] S503. If the flow rate exceeds the target value, that is, Z > X, lower the opening and closing ratio of the valve by the reduced amount ΔN until N = N - ΔN and Z ≤ X;

[0027] S504. During the entire adjustment process, always ensure that the change range of the flow rate |ΔZ| = |Z - Z| < 5 liters per minute to achieve the required stable flow rate accuracy.

[0028] Further, during the entire adjustment process, always ensure that the change range of the flow rate is not greater than the given standard to ensure the accuracy of the flow rate. Specifically, it also includes:

[0029] S601. If |ΔZ| is greater than or equal to 6, adjust the length of the flow rate measurement period R to more finely control the adjustment speed and re - adjust, that is, |R| = R + 5 seconds;

[0030] S602. Repeatedly execute the adjustment steps until the conditions |R| ≤ 5 seconds and |R - R| < 0.3 are met. At this time, N is used as the optimal valve position to provide the optimized flow rate.

[0031] Preferably, the heat treatment of the product after the surface modification is carried out in a nitrogen - protected atmosphere, including:

[0032] S701. Control the nitrogen flow rate within a predetermined range;

[0033] S702. Set the heat treatment temperature at an optimal value of X °C;

[0034] Among them, it is necessary to maintain a constant temperature for more than t hours;

[0035] S703. Adjust based on the specific thermodynamic conditions of the product after the surface modification in a nitrogen - protected atmosphere.

[0036] Further, the adjustment based on the specific thermodynamic conditions of the product after the surface modification in a nitrogen - protected atmosphere includes:

[0037] S801. If the nitrogen flow rate V is less than the minimum flow rate Vmin, increase the nitrogen supply until it reaches Vmin;

[0038] During heat treatment, if the mass m of the product is less than the target mass mgoal, the temperature is appropriately increased until the product meets the quality standard;

[0039] S802, when the heating time t reaches the set time T, stop the heat treatment, if not, continue heating;

[0040] S803, based on the changes in temperature and quality during the actual heating process, the heating power is adjusted in real time to ensure the optimal performance of the final product.

[0041] Furthermore, based on the changes in temperature and mass during the actual heating process, the heating power is adjusted in real time including:

[0042] S901, if the actual temperature measured is lower than the set temperature Y°C, increase the heating power according to a certain proportion;

[0043] S902, when the product quality is lower than the threshold mmin, the quality of the final product is increased to be higher than the threshold mmin by increasing the amount of raw materials;

[0044] S903, when it is detected that the mass or volume has a large deviation △m>△m0 or △V>△V0, reduce the power or stop feeding until the mass meets the target range, △m represents the mass deviation, and △V represents the volume deviation;

[0045] S904, implement feedback control strategy, according to the formula such as temperature difference △T=|set temperature Y actual temperature|>Tmin, then the power increment △P adjusted by the heater is △T*C, where C is the temperature-power conversion coefficient, dynamically adjust the power supply intensity of the heater to maintain the temperature close to the preset target range and achieve stable production.

[0046] Furthermore, implementing the feedback control strategy also includes:

[0047] S1001, judging whether the actual nitrogen flow exceeds the allowable range: when the ratio of the actual nitrogen flow to the standard nitrogen flow Qactual / Qstandard is not between 95 and 1.05, the nitrogen flow rate is corrected to an appropriate level according to the formula Qdesired=Qtarget*(1+Cdev*ε);

[0048] S1002, if the apparent density ρ of the final product measured during the heat treatment process does not meet the standard: if the apparent density difference δp = |target density ρg and measured density ρs| exceeds the threshold pmin, that is, δp>pmin, it is necessary to modify the heat treatment conditions and readjust them to ensure that they meet the quality standards;

[0049] S1003. If the specific surface area B of the product does not meet the requirements at a specific temperature point Z °C, and the difference Bdifference = B - Bexp between the actual area B and the expected area Bexp exceeds ±β, then the heat treatment conditions should be changed accordingly, such as adjusting the temperature and time, to ensure that B is within the target range Btarget, that is, the principle of β < Bdifference < +β should be followed;

[0050] S1004. For products that do not meet the regulations, secondary treatment is carried out. According to the formula, if the change in thermal effect η > ηlimit, where η is the entropy increase of the current process and ηlimit is a preset maximum limit, the heat treatment power needs to be further reduced and the heat treatment duration needs to be increased to meet the product requirements and achieve quality control;

[0051] The secondary treatment for products that do not meet the regulations includes:

[0052] S1101. After finding that the samples that failed the first treatment, put them back into the treatment device again;

[0053] S1102. Verify whether the parameters of the treatment device meet the initial set parameters;

[0054] Re - conduct the heat treatment under new conditions, including but not limited to adjusting the heating time and temperature until the samples meet the standards; and,

[0055] S1103. Determine the influence degree δE of the final thermal effect on the material properties: If δE < δEcrit, where δE is the influence degree of the product's final thermal effect on the cycle efficiency, and δEcrit is the standard boundary for the decline of the cycle life performance, then it is determined that the second heat treatment is effective and the product meets the expectations. Otherwise, continue the repetition process until qualified products are output.

[0056] The embodiment of the present disclosure provides a preparation method of a high - nickel NCM ternary cathode material, which is characterized by including the following steps: adding a complexing agent to a nickel - cobalt - manganese hydroxide precursor, a lithium salt, and a mixed alkali solution, and performing a stirring reaction to form a uniformly mixed solution; based on the uniformly mixed solution, controlling the crystal growth rate and morphology by adjusting the PH value to improve the surface structure stability; performing heat treatment on the surface - modified product under a nitrogen - protection atmosphere to obtain a high - nickel ternary material, thereby ensuring good structural integrity and cycle performance. Through the solution of the embodiment of the present disclosure, the problems of unstable surface structure and poor cycle performance of the high - nickel NCM ternary cathode material during the preparation process can be solved. Description of the Drawings

[0057] In order to more clearly illustrate the technical solutions of the exemplary implementation methods of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0058] Figure 1 It is a flow chart of a high-nickel NCM ternary positive electrode material and its preparation method;

[0059] Figure 2 This is a flow chart based on the heat treatment of the surface modified product under a nitrogen protection atmosphere;

[0060] Figure 3 This is a flow chart for controlling the nitrogen flow rate to X liters / minute to maintain stability;

[0061] Figure 4 It is a flow chart for opening the gas supply valve V and observing the flow meter reading to confirm that the actual inflow gas flow rate is set to be within the target range at a flow rate of X liters / minute;

[0062] Figure 5 If the measured nitrogen flow does not meet the standard of Q=X, the flow rate is adjusted by changing the state of the regulating valve until it meets the standard;

[0063] Figure 6 It is a flowchart for ensuring that the flow rate change amplitude is not greater than the given standard during the entire adjustment process to ensure the flow rate is accurate and specific;

[0064] Figure 7 This is a flow chart based on the heat treatment of the surface modified product under a nitrogen protection atmosphere;

[0065] Figure 8 It is a flow chart adjusted based on the specific thermodynamic conditions of the surface-modified product under a nitrogen protective atmosphere;

[0066] Fig. 9 It is a flowchart for adjusting the heating power in real time based on the changes in temperature and mass during the actual heating process;

[0067] Fig.10 It is a flow chart for implementing the feedback control strategy;

[0068] Fig.11 It is a flow chart for secondary processing of products that do not meet regulations. DETAILED DESCRIPTION

[0069] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0070] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0071] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0072] Next, refer to Figure 1 Description of a high nickel NCM ternary cathode material and its preparation method:

[0073] S101: Mix together the accurately measured nickel-cobalt-manganese Ni-Cu-Mn hydroxide precursor, the appropriate proportion of lithium salts such as lithium carbonate, lithium bicarbonate, etc., and a certain concentration of mixed alkali solution according to a preset ratio, add an appropriate amount of chelating agent such as citric acid, EDTA, etc. in the reactor, and then stir the reaction to form a uniform mixed solution at a suitable reaction temperature such as 60 to 90°C and a reaction time ranging from several hours to several days, according to the specific equipment and raw material characteristics. The purpose of this step is mainly to allow the raw materials to react fully and ensure the uniformity of the composition distribution of the reaction products. For example, when the ratio of nickel, cobalt and manganese can be adjusted to Ni: Co: Mn = 0.8: 0.15: 0.05, if a total molar amount of 1 mole of material is to be synthesized, theoretically 0.8 mol of NiOH is required. 2 , 0.15molCoOH 2 , and 0.05molMnOH 2 At the same time, sufficient lithium carbonate and mixed alkali metal salt solution are added to meet the required lithium element in the chemical reaction equilibrium state. In order to ensure the appropriate concentration of metal ions in the solution, deionized water is generally used to prepare alkaline solution and add it as needed. In this process, the mechanical action generated by a mechanical or air pump is used to make the various substances fully mixed and maintain a constant pH value to control the uniform growth of the grains. Through such meticulous operation steps, a mixed solution base with uniform composition and consistent morphology can be effectively obtained.

[0074] S102: Controlling the crystal structure of the material by adjusting the pH value based on the uniformly mixed solution. This step usually involves using an appropriate acid or alkaline reagent to adjust the pH to a suitable range, generally around 10-13, so that the metal elements in the solution can be effectively precipitated into a specific form, thereby controlling the crystal form of the material particles. For example, some ammonia water can be added to increase the concentration of OH- in the system, thereby increasing the precipitation rate and promoting rapid crystal growth; on the other hand, dilute acid can also be used appropriately to reduce the rapid formation of crystals and avoid the generation of irregular shapes, ensuring that the particles have better shapes and larger average particle sizes. At the same time, it is also necessary to maintain a reasonable match between the temperature, stirring speed and other factors in the solution at this stage in order to further improve the surface properties of the product. Once the crystal growth conditions are adjusted, continue to maintain a stable form under appropriate pH conditions for a period of time, thereby effectively controlling the growth direction and final structure of the product crystals.

[0075] After the above detailed steps are carried out, semi-finished products with preliminary optimized surface and good crystal morphology are formed; finally, these semi-finished products are transferred to the heat treatment process for further processing. This can not only improve the stability of the crystal particles themselves but also lay an important foundation for the subsequent processing steps.

[0076] S103: Based on the surface-modified product, place it in a specially designed reactor pre-filled with a high-purity nitrogen gas N2 content ≥ 99% for a high-temperature calcination process. This step mainly involves evenly spreading the resulting product on a quartz boat and then slowly increasing its temperature rise rate to a certain value and maintaining a constant temperature and heat preservation for several hours. During this period, due to being in an inert environment, it can effectively avoid impurity contamination and the negative effects of oxygen ions participating in the reaction, ensure the consistency of the chemical composition of the generated material, and more importantly, it can also promote the degree of crystallization through this method, so that the entire product has higher strength and better electrical properties. Finally, after cooling and taking out, the required high-quality ternary NCMnickel-cobalt-manganese positive electrode material is obtained. The specific temperature selection can be optimized and determined based on the specific characteristics and test data of different nickel ratio materials. Generally, the most suitable section between 600°C and 900°C will be selected as the reference range for processing.

[0077] Through the operation of the above steps, the problem of "unstable surface structure and poor cycle performance of high-nickel NCM ternary positive electrode materials during the preparation process" can be solved. The basic material with good surface properties and micromorphology is obtained by adding appropriate complexing agents, optimizing stirring conditions, and strictly controlling pH values. Then, further heat treatment under a controlled environment improves the integrity of the crystal structure and the wear resistance under battery working conditions. The entire process design ensures that the various electrical properties of the finished product meet the standards and achieves the goal of minimizing the control of material surface defects, providing a strong guarantee for the subsequent battery component integration, and significantly improving the surface stability of the material and the consistency and long-term stability of battery performance.

[0078] Next, refer to Figure 2 Describe the specific steps involved in the heat treatment of the surface modified product in the preparation of a high nickel NCM ternary cathode material:

[0079] S201: The safety and efficiency of the heat treatment process is ensured by controlling the gas flow rate in the nitrogen atmosphere. The gas flow rate needs to be kept stable within the range of X liters / minute, where X is between 5 and 10 liters / minute, to prevent oxidation and other phenomena that may damage the microstructure of the positive electrode material. The nitrogen flow provides an ideal non-oxidizing atmosphere and ensures that the material is not exposed to air and contaminated or oxidized during the reaction.

[0080] S202: The surface-modified product is heated at a selected temperature Y degrees Celsius, which is selected from a range of 200 to 600 degrees Celsius. The heat treatment temperature determines the growth of the microscopic grains of the material and the final material properties, including electrochemical characteristics and physical properties, so it is very important to choose the appropriate temperature.

[0081] Next, after the set temperature stabilizes, start the heating program and start timing. Keep this state for at least 8 hours and up to 24 hours. Use the timer to accurately record the time required for the entire heat treatment process. Here, Z must be within the above 8-24 hour range. This will fully activate the positive effects of the heat treatment.

[0082] Finally, for low temperature conditions, that is, if the set processing temperature Y is lower than 450 degrees Celsius, the total heat treatment duration Z is increased according to specific conditions to ensure that the processing volume meets a certain minimum accumulated temperature standard T = 108000 ° C min. This accumulated temperature standard can ensure that the high nickel positive electrode material has a good and stable lattice structure and excellent electrochemical properties; in this way, even if a lower processing temperature is used, the influence of the lower temperature can be compensated by extending the heat treatment time, thereby ensuring the consistency of product performance while reducing energy consumption or process complexity.

[0083] The above is a description of the specific steps based on this feature. In a laboratory environment or industrial production, it is necessary to flexibly configure the various parameters in the heat treatment conditions, such as nitrogen flow rate, heating rate and holding time, according to the specific equipment capabilities and product quality control requirements, in order to obtain product quality indicators that meet the requirements.

[0084] Next, refer to Figure 3 Describe the specific steps of a method for controlling the nitrogen flow rate in the preparation of a high-nickel NCM ternary cathode material:

[0085] S301: Remove potential moisture by adjusting the nitrogen introduction process. Specifically, in the preheating stage of the gas pipe, the gas pipeline needs to be preheated to a suitable value U degrees Celsius in the range of 100°C to 250°C to effectively remove moisture residues in the system to reduce the adverse effects that may be introduced into subsequent processes; at the same time, after opening the air inlet valve V, it is necessary to observe the indicated value of the flow meter to ensure that the current flow rate meets the target control requirements;

[0086] S302: fine correction of the flow rate is achieved by adjusting the actual setting state of the valve V and the configuration parameters of the nitrogen pressure reducing valve, which includes opening the pressure reducing valve regulator and repeatedly testing and adjusting until the error △X between the measured effective nitrogen gas flow rate X and the expected rate is reduced to less than 1 liter / minute, and the absolute value of this deviation needs to be continuously monitored. If it exceeds ±5 liters / minute, immediate feedback is required to perform further adjustments to ensure stable and reliable operation of the system;

[0087] S303: After the above steps, the actual gas transmission value needs to be measured regularly or as needed and compared with the standard parameters. If the deviation value |△X| exceeds the predetermined limit, that is, the range above 5 liters / minute, the process should be rechecked immediately and necessary corrective measures should be taken to ensure that the final flow difference |△X| does not exceed 0.5 liters / minute to ensure that the airflow always maintains an even and continuous supply throughout the production stage, thereby achieving high-precision operation control of the process.

[0088] Next, refer to Figure 4 Describe the specific steps of a method for accurately controlling the airflow supply in the preparation of a high-nickel NCM ternary cathode material:

[0089] S401: Setting gas pressure - According to claim 3, open the gas supply valve V and introduce gas into the system. Adjust the pressure value of the gas supply through the gas pressure regulating device S. Make sure that the device S is adjusted to the predetermined position P, where the P range should be maintained between 1 and 2 MPa to ensure that nitrogen can be accurately and stably supplied. Through this step setting, the fine adjustment of the gas supply pressure is achieved to ensure that it is stable and meets the technical parameter range required for production.

[0090] S402: Calibrate nitrogen flow rate – When the gas pressure has been adjusted, determine the actual nitrogen flow rate Q by observing the display on the flow meter. The actual reading Q should be consistent with the desired target gas flow rate X, and the deviation is required to be controlled within a certain range, that is, the actual gas flow rate deviation △Q absolute value |△Q| is required to be less than 1 liter / minute. If the read data does not match or deviates greatly, it indicates that the gas valve state needs to be further adjusted to reduce the error △Q until the gas flow rate is ensured to work within the expected accuracy range.

[0091] S403: Correct the deviation to ensure accuracy - Assume that the data read in the first step has a significant deviation △Q compared with the expected target airflow speed X, and △Q is greater than the specified allowable error of 5 liters / minute. In order to achieve the required accuracy of the process, measures must be taken to correct the deviation, that is, by adjusting the state of the regulating valve, Q gradually approaches X and the deviation △Q is kept below the allowable standard of less than 0.5 liters / minute, thereby effectively reducing the deviation. If the flow deviation still cannot fall within the allowable error range after the first attempt, it is necessary to repeat the above-mentioned regulating valve operation until the calibration step is completed under the condition that the accuracy requirements are finally met.

[0092] These steps effectively ensure that the airflow rate remains accurate and consistent throughout the production process, which is conducive to the production of high-performance high-nickel NCM ternary positive electrode materials.

[0093] Next, refer to Figure 5 Describe the specific steps of a method for accurately controlling nitrogen supply in the preparation of a high-nickel NCM ternary cathode material:

[0094] S501: Initial setting and flow calibration: One of the technical features of the present invention is to optimize the gas supply process in the preparation process of high-nickel NCM ternary positive electrode materials. Initially, a regulating valve is set, and its opening and closing ratio is set to N%, where N is in an adjustable range of 50%-80%. The nitrogen supply loop is opened under the set N, and the flow rate Z entering the preparation reaction system in a standard time unit, such as per minute, is measured.

[0095] S502: Adjust the flow rate to the target value: When the monitored nitrogen flow rate Z is lower than the preset standard value X, the valve body opening and closing ratio needs to be fine-tuned to increase the nitrogen supply rate, that is, by calculating the increased opening increment ΔN, the valve state is updated according to the formula N=N+ΔN until the measured Z≥X; if the actual flow rate Z exceeds X, the flow rate is reduced by the same strategy, that is, adjusted according to the formula N=N-ΔN until Z≤X is achieved. This ensures the precise gas supply standard required for the preparation reaction, and in this dynamic adjustment process, ensures that the change of the gas supply rate is controlled within a suitable fluctuation range, that is, each change does not exceed 5 liters / minute, to meet the required accuracy requirements.

[0096] S503: Maintain a stable flow rate: Dynamically monitor the nitrogen supply flow rate throughout the adjustment process, and monitor the instantaneous speed of N2 flowing through the reaction vessel again after each valve adjustment until a standard rate Z = X that meets the predetermined fluid transmission conditions is obtained. In addition, during the adjustment process, it is always necessary to pay attention to the flow rate fluctuation range that cannot be greater than |ΔZ| = |ZZ| < 5L / min, which will help achieve and maintain the stable gas flow rate and gas concentration environment required in the preparation process.

[0097] Next, refer to Figure 6 Describe the specific steps for accurately controlling the solution mixture supply rate in the preparation of a high-nickel NCM ternary cathode material:

[0098] S601: By controlling the valve position Z in the fluid device and setting the standard limit of the flow deviation ΔZ, monitor whether the difference between the actual supplied solution and the set flow rate reaches a predetermined 6 units or more. If the actual measured deviation value |ΔZ| is equal to or exceeds this threshold value of 6 units, it indicates that the speed of liquid mixing supply in the current system needs to be fine-tuned to improve accuracy and stability. This step is mainly to evaluate the current state and determine whether there is a need for adjustment.

[0099] S602: If adjustment is indeed necessary, increase the flow detection time period R. In actual operation, the flow detection time period is usually extended by 5 seconds each time. This means that each adjustment will make the inspection interval longer, thereby more finely controlling the process speed of valve position fine-tuning. Such a control strategy helps to gradually reduce the possibility of target instability caused by excessive flow rate changes.

[0100] S603: Repeat the adjustment of the valve position and monitor the two sets of data |ΔZ| and the time period change |RR|. The goal here is to make the two values ​​|R| and the valve adjustment rate |RR| reach the predetermined accuracy level |R|≤5 seconds and the change rate is less than 0.3. The valve position N recorded at each checkpoint will be adjusted according to the new equilibrium state after the previous adjustment until the system enters a state closest to the set rate and changes smoothly and steadily. At this time, N is the final optimal valve position. This last step is to continuously monitor and correct on the basis of the previous steps to ensure that the flow rate in the supply process can not only quickly reach the desired value but also be stable enough.

[0101] Such an adjustment step dynamically adapts to find the best solution that meets both high efficiency and high quality requirements, thereby making the solution mixing process more accurate and efficient.

[0102] Next, the heat treatment steps of the surface modified product under nitrogen protection in the preparation of a high nickel NCM ternary positive electrode material are given with reference to the characteristic description:

[0103] S701: Establishment and control of nitrogen atmosphere

[0104] This feature first involves the establishment of a nitrogen protective atmosphere, and in this process, the safety and controllability of the entire heat treatment process are ensured by finely regulating the nitrogen flow rate within a preset effective range. This flow rate regulation can be achieved by equipping a nitrogen generation system with a precise flow metering device to ensure that the oxygen content in the entire system is minimized to reduce the risk of side reactions or impurity formation.

[0105] S702: Setting and implementing a constant temperature process at a specific temperature

[0106] This step includes placing the surface-modified material into a suitable furnace or sintering device, setting the heat treatment temperature at a preferred specific temperature point such as X degrees Celsius, and then maintaining the temperature for a sufficiently long time to ensure that the heat treatment is fully and uniformly carried out. This operation requires the use of equipment with good temperature control performance and uniform heat distribution, such as an atmosphere sintering furnace or a rotary heating furnace, so as to accurately reach the required heat treatment temperature and ensure that the temperature in the furnace is uniform to reduce product inconsistency during heat treatment.

[0107] S703: Fine-tuning of thermodynamic conditions and cooling

[0108] After the heat treatment is completed and the above-mentioned constant conditions are maintained for a period of time, that is, at least t hours, the heat treatment details under nitrogen protection can be further optimized according to the product characteristics and changes in process conditions. For example, the flow rate and pressure balance can be dynamically adjusted to match the rate of furnace temperature drop, so that the crystal structure of the product can be better maintained and optimized, improving the yield while ensuring that the material has ideal application performance. In this process, it is also necessary to pay attention to the appropriate cooling strategy to prevent excessive cooling from causing product stress changes, which may cause material microscopic defects or structural changes that affect the electrochemical performance of the final product.

[0109] Next, refer to Figure 8 Describe the specific steps related to heat treatment in a method for preparing a high-nickel NCM ternary cathode material:

[0110] S801: By controlling the gas atmosphere-method, in the process of implementing the preparation of the high-nickel NCM ternary positive electrode material, the positive electrode material that has been surface-modified is subsequently treated under nitrogen protection conditions. In order to ensure that oxygen in the treatment process does not have an adverse effect on the positive electrode material, nitrogen is used as a carrier and protective atmosphere, and a certain flow rate range is set. In the actual process, when it is detected that the flow rate V in the current process environment is less than the preset minimum limit Vmin, the nitrogen supply is automatically increased to meet the requirements of the process parameters.

[0111] S802: Controlling the temperature to meet the quality target - This step is to make the treated material meet the specific target quality mgoal. The product quality m needs to be continuously monitored throughout the heat treatment process. If the actual mass measured at a certain heating stage is less than the expected mass, the internal operating temperature of the heating furnace needs to be increased accordingly, so that the material can further lose water or other low-boiling substances to reduce the weight of the material until the final quality meets the standard. This step is achieved by dynamically monitoring the heat input and temperature changes and accurately fine-tuning them.

[0112] S803: Setting termination conditions - A specific termination time of the heat treatment needs to be set during the heat treatment stage. According to the claims, the entire processing program is stopped after the preset heating duration T. Similarly, if the heating time t does not reach the preset value T during this cycle, the heating will continue to ensure that the product undergoes a complete heat treatment process to obtain the desired effect. This step requires the precise setting of the timer and the integration of this control strategy in the equipment.

[0113] S804: Dynamically adjust the heating power - During the actual heating process, the material quality changes and the actual operation of the heating furnace should be continuously monitored. If the quality deviates from the ideal state or other heat treatment parameters deviate from expectations, the energy input of the heating source, such as electricity, natural gas, etc., can be adjusted immediately to ensure that the product can meet the expected quality and process optimization effect.

[0114] The above steps comprehensively ensure that the high-nickel NCM ternary material has stable production performance during the manufacturing process and meets the target product quality standards required by the design performance.

[0115] Next, refer to Fig. 9 Describe the specific steps of real-time adjustment of heating power in the preparation of a high-nickel NCM ternary cathode material:

[0116] S901: Monitor the actual temperature in the heating chamber and the quality changes of the materials to be prepared during the entire heat treatment process. When the monitoring system detects that the current actual temperature does not reach the set temperature Y℃ required by the process flow, the proportional factor of the power increase is calculated according to a certain linear or nonlinear function to dynamically adjust the power supplied to the electric heating device; that is, by adjusting the current or voltage to change the heating rate, so as to increase the drying or sintering temperature of the positive electrode material precursor until it is close to Y℃.

[0117] S902: During the production process, if the continuous quality monitoring results show that the actual total weight of the synthesized powder material is less than the predetermined minimum limit mmin, the production needs to be suspended and the reason for the decrease in output needs to be evaluated to see if it is due to insufficient chemical raw materials added. If it is due to the above reasons, appropriate precursors or intermediates need to be added again according to the formula requirements to ensure that the output meets the minimum requirement mmin batch.

[0118] S903: When the automated quality monitoring unit on the production line reports that a mass or total volume fluctuation exceeding the acceptable error range is detected during continuous processing, that is, when the deviation △m between the actual value and the expected value is greater than △m0 and / or the actual volume △V exceeds the set allowable upper limit deviation △V0, the material flow is automatically reduced or directly cut off while the power supply to the heating element is reduced or suspended to ensure that the quality of the final product is within the controlled range without excessive evaporation or agglomeration, thereby avoiding the occurrence of defective products.

[0119] S904: Using the principle of feedback controller, the regulation strategy of the heating system is set to a closed-loop structure. That is, if the sensor finds that the difference between the actual heating environment temperature and the target temperature setting value Y exceeds a preset tolerance level Tmin, the temperature difference △T is calculated, and its absolute value represents the deviation, and then multiplied by the calibration parameter C mentioned above to convert this quantity into an equivalent power change unit △P△P is proportional to △T, then the power input on the heating device can be increased or reduced accordingly to make corrections so as to keep the overall operating conditions consistent with the predetermined range as much as possible to ensure the performance stability and consistency of the finished product.

[0120] Suppose that during the specific operation, we find that the actual working temperature is 3 degrees Celsius lower than the target and the mass is 50g lighter than expected during a certain period of time. First, we will adjust the program to make the actual heating temperature difference △T 3 degrees, and on this basis, combine the preset conversion coefficient C, for example, assume that the coefficient C is set to increase the output power by 50 watts for each degree; in this way, we can quickly approach the standard heating parameter value Y and maintain its relative stability by adjusting the additional power △P=C*△T=150W to the heating element. If the system reports that the final powder mass is less due to evaporation loss or other physical and chemical factors, the automatic feeder will be used to add an appropriate amount of mixed raw materials to make up for this part of the material loss. This method can not only maintain continuous production but also ensure the high consistency of products between batches.

[0121] The above steps summarize the key links of real-time adjustment of the heating process, which effectively improves the controllability of finished product quality and production efficiency while ensuring material uniformity.

[0122] Next, refer to Fig.10 Describe the specific steps of the feedback control strategy involved in the preparation method of a high-nickel NCM ternary cathode material:

[0123] S1001: Nitrogen inlet rate control - In order to ensure the stability of nitrogen inlet and maintain it within the set range Qactual / Qstandard between 0.95 and 1.05, a dynamic control system is used to monitor the actual flow rate and compare it with the target flow rate Qtarget. Once the system detects that the deviation between the two is too large, the following equation is used for dynamic regulation: Qdesired = Qtarget*1+Cdev*ε. Where Cdev is the correction factor; ε represents the deviation ratio. The calculated result is used as the target flow rate of the new nitrogen, so as to achieve precise adjustment of the nitrogen inlet process and ensure the uniformity and reliability of heat treatment under nitrogen atmosphere.

[0124] S1002: Standardization of the apparent density of the final product - Use online measurement technology and quality control algorithms to evaluate the apparent density ρs of the prepared cathode material, and compare the actual measured value with the target density ρg. If the difference between the measured value and the target value exceeds a certain threshold δp>pmin, that is, δp=|ρg-ρs| exceeds the standard value pmin, then one or more operating conditions in the heating process must be adjusted according to this deviation for correction. Specific practices may include extending the insulation time, adjusting the heating rate, or improving environmental conditions, until the product's apparent density falls within the specified specifications.

[0125] S1003: Specific surface area optimization adjustment - Test the material sample after heat treatment, and compare the actual specific surface area B of the sample with its preset ideal value Bexp at a certain temperature point Z℃. Assuming that the relative error between the two, Bdifference = B-Bexp, is greater than plus or minus β±β, this means that the sample surface area has not reached the target value in the current state, and it is necessary to improve it by optimizing the heat treatment parameters, including increasing / decreasing the treatment temperature and appropriately extending the time, so that the product specific surface area falls within the preset ideal range [Btarget, Btarget+β].

[0126] S1004: Secondary processing adjustment after quality monitoring - If the initially manufactured product is found to still not meet the quality requirements after testing, for example, due to excessive energy dissipation η>ηlimit caused by thermodynamic instability, this abnormality can be corrected by reducing the heating work and increasing the duration of the treatment. This can reduce the unpredictable entropy change in the production process, reduce excessive energy loss and avoid affecting the properties of the positive electrode material; on the contrary, if it is found that the overall heat input is insufficient and affects the quality of the finished product, the input energy should be appropriately increased and the periodicity of the thermal cycle should be maintained until the quality indicators of the finished product meet the specifications.

[0127] Next, refer to Fig.11 Describe the specific steps for reprocessing non-compliant high-nickel NCM ternary cathode materials to meet performance requirements:

[0128] S1101: When it is found during production monitoring that the samples after the first treatment cannot meet the predetermined performance standards, the batch of products will be sent back to the specific processing equipment; this equipment can accurately control the various parameters of the heat treatment. At this stage, it should be ensured that all unqualified samples are returned to the processing container intact to avoid quality problems caused by mixing batches that have met the standards and batches that have not met the standards;

[0129] S1102: Check and verify that the equipment settings for heat treatment remain the same as the initial process - this means that the temperature range and heating rate and treatment time should be consistent. This verification process is designed to ensure that any potential deviations can be detected and subsequent remedial measures are feasible and targeted. If it is confirmed that the parameter settings are normal but the sample still does not meet the standards, further adjustments are required;

[0130] S1103: Based on the above verification, adjust the heat treatment conditions, such as increasing the temperature or extending the heating duration, to perform secondary heat treatment on the material until its chemical and electrochemical indicators reach the required performance level. Here, the specific processing steps and related conditions of each batch of products must be carefully recorded for future analysis and reproduction;

[0131] S1104: Use appropriate testing methods to evaluate key performance changes such as cycle life of positive electrode materials after secondary heat treatment - if the measured thermal effect on the final cycle performance δE of the batch is less than the threshold δEcrit, it is considered that the remedial process has successfully improved product quality; on the contrary, if the measured impact is still beyond the acceptable range, the above process should be repeated until all positive electrode samples meet the standards before they can be shipped. This step involves experimental comparison and the acquisition and calculation of quantitative data, aiming to verify the final improvement effect.

[0132] In actual operation, when this device is used, the specific steps must first be performed according to the proposed preparation method in order to produce a high-quality high-nickel NCM nickel-cobalt-manganese ternary positive electrode material. The entire process can be divided into three core links: the first is to prepare a uniform mixed solution: in this process, the nickel-cobalt-manganese hydroxide precursor and lithium salt as raw materials are first fully mixed with the pre-prepared mixed alkaline solution, and a special chelating agent is added on this basis. The addition of the chelating agent helps to further improve the chemical reaction activity and stability between various chemical substances, ensuring that these materials can be evenly mixed to form a stable and uniform mixed solution. This step is crucial to the uniformity and homogeneity of the subsequent synthetic products; then enter the second important step, which is to adjust the pH value of the formed uniform solution to control the grain growth rate and micromorphology of the target compound, and further achieve the goal of improving the surface structure stability of the final product. This step requires precise condition control to ensure that the pH value can fluctuate within an appropriate range, so that the material can show better electrochemical performance and improve the bonding force between particles, thereby ensuring the good stability of the material; the last step is the heat treatment process. After completing the previous step, the material after preliminary surface modification is transferred to a device specially designed for high-temperature treatment and heated to a specified temperature for a period of time under a nitrogen protective gas environment. This operation can effectively promote the crystallization degree of the material at high temperature, so that the finished product has a good microcrystalline morphology and higher structural integrity and excellent cycle performance. In this stage, the consistency and stability of the product are guaranteed by precisely controlling the heating temperature and atmosphere composition, and the appropriate final material type can also be selected according to different application requirements. In the entire production process, each key link needs to be strictly operated and executed under the specified conditions and parameters. These steps are closely linked, and any problem in any part may affect the subsequent synthesis effect and the quality performance of the final output. Only when all components and process work in a coordinated manner can the goal of preparing high-performance high-nickel ternary positive electrode materials be achieved, and they have excellent application prospects and economic benefits.

[0133] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the embodiments of the present disclosure. It should be understood that the above description is only the specific implementation method of the embodiments of the present disclosure and is not intended to limit the protection scope of the embodiments of the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the protection scope of the embodiments of the present disclosure.

Claims

1. A method for preparing a high-nickel NCM ternary positive electrode material, characterized in that: It includes the following steps: S101, adding a complexing agent to nickel-cobalt-manganese hydroxide precursor, lithium salt and mixed alkali solution, and carrying out stirring reaction to form a uniform mixed solution; S102, based on the uniform mixed solution, controlling the crystal growth rate and morphology by adjusting the pH value to improve the surface structure stability; S103, carrying out heat treatment on the surface-modified product under the nitrogen protection atmosphere to obtain a high-nickel ternary material, so as to ensure good structural integrity and cycle performance.

2. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 1, characterized in that: Carrying out heat treatment on the surface-modified product under the nitrogen protection atmosphere includes: S201, controlling the nitrogen flow rate to be stable within X L / min, where X ranges from 5 to 10; S202, setting the heating temperature at Y °C, which is selected within the range of 200 to 600 °C; S203, starting the timer for Z time when the temperature Y is stable, ensuring that Z is within the time interval of 8 to 24 hours; S204, if the temperature Y is lower than 450 °C, increasing the treatment time Z until the condition T = Y×Z≥108000 °C·min is satisfied to ensure good structural integrity.

3. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 2, characterized in that: Controlling the nitrogen flow rate to be stable at X L / min includes: S301, preheating the nitrogen inlet pipe to U °C to remove the water vapor inside the pipeline, where U is preset between 100 and 250 °C; S302, opening the gas supply valve V and observing the reading of the flow meter to confirm the actual inflow gas flow rate, setting V to maintain the target interval of the flow rate X L / min between 5 and 10; S303, adjusting the nitrogen pressure reducing valve W, continuously fine-tuning until the error △X between the actually measured nitrogen flow rate and the predetermined flow rate X L / min is less than 1 L / min; S304, when measuring the flow rate, if |△X|>5, repeat the above operations until the condition △X≤0.5 is satisfied, so that the gas flow is stable and uniform.

4. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 3, characterized in that: Opening the gas supply valve V and observing the reading of the flow meter to confirm that the actual inflow gas flow rate is set to be within the target interval at the flow rate X L / min includes: S401, adjusting the gas supply pressure regulating device S to the predetermined position at P °C, where P ranges from 1 to 2 MPa; S402, visually observing the flow meter to confirm whether the actually measured value Q of the inflowing nitrogen is equal to X, and requiring the error △Q to satisfy the condition |△Q| = |Q - X| to be less than 1 L / min; S403, if the measured nitrogen flow does not meet the standard of Q = X, that is, △Q>5, adjusting Q by changing the state of the regulating valve to make the deviation △Q≤0.5; S404, if the deviation △Q still exceeds the allowable threshold, repeatedly adjust the valve until the deviation is less than or equal to the given standard.

5. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 4, characterized in that: If the measured nitrogen flow does not meet the standard of Q = X, adjusting the flow rate by changing the state of the regulating valve until it meets the standard, specifically including: S501, initially setting the opening and closing ratio of the regulating valve to N%, where N ranges from 50% to 80% and starting to supply gas; S502, after measuring the inflow Z L / min, if Z<X, increasing the opening and closing ratio by the value of ΔN to ensure that Z≥X under the condition of N = N + ΔN; S503, if the flow velocity exceeds the target value, that is, Z>X, then the valve opening and closing ratio is reduced according to the reduced amount ΔN until N=NΔN and Z≤X; S504, during the entire adjustment process, the flow rate change amplitude |ΔZ|=|ZZ|<5 liters / minute is always ensured to achieve the required stable flow rate accuracy.

6. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 5, characterized in that: During the entire adjustment process, the flow rate change amplitude is always ensured not to exceed the given standard to ensure the flow rate is accurate. The specific implementation also includes: S601, if |ΔZ| is greater than or equal to 6, the length of the flow measurement period R is adjusted to more precisely control the adjustment speed and readjust, that is, |R|=R+5 seconds; S602, repeatedly performing the adjustment steps until the conditions |R|≤5 seconds and |RR|<0.3 are met, at which time N is used as the optimal valve position to provide the optimal flow.

7. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 1, characterized in that: The surface-modified product is subjected to heat treatment under a nitrogen atmosphere, comprising: S701, controlling the nitrogen flow rate within a predetermined range; S702, the heat treatment temperature is set at an optimal value X°C; Among them, it is necessary to maintain a constant temperature for more than t hours; S703, making adjustments based on the specific thermodynamic conditions of the surface-modified product under a nitrogen protective atmosphere.

8. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 7, characterized in that: Adjustments based on the specific thermodynamic conditions of the surface-modified product under a nitrogen atmosphere include: S801, if the nitrogen flow rate V is less than the minimum flow rate Vmin, increase the nitrogen supply until it reaches Vmin; During heat treatment, if the mass m of the product is less than the target mass mgoal, the temperature is appropriately increased until the product meets the quality standard; S802, when the heating time t reaches the set time T, stop the heat treatment, if not, continue heating; S803, based on the changes in temperature and quality during the actual heating process, the heating power is adjusted in real time to ensure the optimal performance of the final product.

9. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 8, characterized in that: Based on the changes in temperature and quality during the actual heating process, real-time adjustment of heating power includes: S901, if the actual temperature measured is lower than the set temperature Y°C, increase the heating power according to a certain proportion; S902, when the product quality is lower than the threshold mmin, the quality of the final product is increased to be higher than the threshold mmin by increasing the amount of raw materials; S903, when it is detected that the mass or volume has a large deviation △m>△m0 or △V>△V0, reduce the power or stop feeding until the mass meets the target range, △m represents the mass deviation, and △V represents the volume deviation; S904, implement feedback control strategy, according to the formula such as temperature difference △T=|set temperature Y actual temperature|>Tmin, then the power increment △P adjusted by the heater is △T*C, where C is the temperature-power conversion coefficient, dynamically adjust the power supply intensity of the heater to maintain the temperature close to the preset target range and achieve stable production.

10. The method for preparing a high-nickel NCM ternary positive electrode material according to claim 9, characterized in that: Implementing a feedback control strategy also includes: S1001, judging whether the actual nitrogen flow exceeds the allowable range: when the ratio of the actual nitrogen flow to the standard nitrogen flow Qactual / Qstandard is not between 95 and 1.05, the nitrogen flow rate is corrected to an appropriate level according to the formula Qdesired=Qtarget*(1+Cdev*ε); S1002, if the apparent density ρ of the final product measured during the heat treatment does not meet the standard: then according to the apparent density difference δp = |target density ρg - measured density ρs| exceeding the threshold pmin, that is, when δp > pmin, it is necessary to correct according to the criterion of re-adjusting by modifying the heat treatment conditions to ensure compliance with the quality standard; S1003, if the specific surface area B of the product is found not to meet the requirements at a specific temperature point of Z °C, then according to the difference between the actual area B and the expected area Bexp, Bdifference = B - Bexp exceeding ±β, it should be executed according to the principle of correspondingly ensuring that B is within the target area Btarget interval, that is, β < Bdifference < +β, by changing the heat treatment conditions such as adjusting the temperature and time; S1004, for the non-compliant products, secondary treatment is carried out. According to the formula, if the change in thermal effect η > ηlimit, that is, η is the entropy increase of the current process and ηlimit is a preset maximum limit value, it is necessary to further reduce the heat treatment power and increase the heat treatment duration to meet the product requirements and achieve controllable quality; The secondary treatment of non-compliant products includes: S1101, when it is found that the sample that fails to meet the standard in the first treatment is put back into the treatment device again; S1102, verify whether the parameters of the treatment device meet the initial set parameters; Re-perform the heat treatment under new conditions, including but not limited to adjusting the heating time and temperature until the sample meets the standard; and, S1103, determine the influence degree δE of the final thermal effect on the material performance: if δE < δEcrit, where δE is the influence degree of the final thermal effect of the product on the cycle efficiency, and δEcrit is the standard boundary for the decline of the cycle life performance, then it is determined that the second heat treatment is effective and the product meets the expectation, otherwise, the repeated process is continued until a qualified product is output.

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