Wide particle size distribution ternary precursor, method of making and use thereof

Abstract

This invention provides a ternary precursor with a wide particle size distribution, its preparation method, and its applications. The precursor is a high-nickel ternary precursor with spherical or near-spherical secondary particles. Its particle size distribution is unimodal, with D50 of 10-13 μm, Span of 1.0-1.3, D10 of 5-8 μm, and D90 of 16-21 μm. The moderate particle size of this ternary precursor ensures that it does not fly away during processing, is easy to coat, and is fully compatible with existing production lines. The wide-distribution unimodal structure achieves graded filling of particles of varying sizes, significantly reducing electrode porosity, resulting in high compaction density and a substantial increase in battery volumetric energy density. It also avoids the sintering performance mismatch problem caused by multimodal distribution. The spherical morphology provides good flowability and dispersibility, resulting in uniform coating. Furthermore, its small specific surface area reduces electrolyte side reactions and improves cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery cathode material precursor preparation technology, specifically relating to a ternary precursor with a wide particle size distribution and a single-peak gradient characteristic, its preparation method, and its application. Background Technology

[0002] Ternary precursors are the core raw materials for preparing lithium nickel cobalt manganese oxide cathode materials, and their particle size distribution directly determines the compaction density, electrochemical performance, and processing performance of the cathode material. Wide particle size distribution ternary precursors, through the gradation effect of large and small particles, can significantly improve the compaction density of the cathode material while ensuring electrochemical performance. They are currently a core material in the field of high-energy-density, long-range power batteries, and have broad application prospects and huge market value in new energy vehicles, energy storage power stations, and other scenarios.

[0003] Current advancements in the preparation of ternary precursors with wide particle size distributions primarily focus on process optimization. These advancements mainly utilize multi-stage reactions, multi-stage mixing, and intermittent seeding to achieve the desired particle size distribution. However, there is a significant lack of research into the structural characteristics of the materials themselves. Publicly available patents generally emphasize improvements in the preparation process: Patent application CN120483288A proposes a method for preparing wide-distribution, large-particle, high-nickel ternary precursors, achieving wide particle size distribution through segmented control of reaction parameters, but it does not address the continuity of the material's internal structure or the elemental gradient distribution; Patent application CN121735317A provides a method for synthesizing wide-distribution precursors, achieving particle size control through multi-step seeding, but similarly neglects the structural consistency and elemental distribution matching of particles with different sizes; Patent application CN121377144A develops a doped and coated wide-distribution precursor preparation technology, improving material performance through doping and coating processes, but it does not delve into the intrinsic relationship between particle interface characteristics and elemental gradient distribution in wide-distribution systems.

[0004] The broad-distribution precursors prepared by existing technologies generally suffer from four core problems: First, the physical mixing process results in obvious particle interfaces, with essential structural differences between different batches of particles; second, the intermittent seeding process leads to uneven element distribution, with abrupt changes in element content among particles of different sizes; third, the multi-step reaction results in poor batch consistency and large fluctuations in product performance; and fourth, the mismatch between particle size structures leads to large differences in expansion coefficients, which can easily cause particle cracking and pulverization during cycling, ultimately resulting in deterioration of cycling performance. Summary of the Invention

[0005] The present invention aims to solve the technical problems existing in the prior art and provide a ternary precursor with wide particle size distribution, its preparation method and application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: Firstly, a ternary precursor with a wide particle size distribution is provided, wherein the ternary precursor is a spherical or near-spherical secondary particle with the chemical formula Ni. x Co y M z (OH)2, where M is Mn and / or Al, x+y+z=1, 0.80≤x≤0.98, 0.01≤y≤0.20, 0.01≤z≤0.20; and the secondary particles have the following particle size distribution characteristics: D0 is 3~5μm, D10 is 5~8μm, D50 is 10~13μm, D90 is 16~21μm, the radial span is 1~1.3, and there is only one peak in the volume-based particle size distribution curve.

[0007] Secondly, a method for preparing ternary precursors with a wide particle size distribution is provided, including: (1) Prepare salt solutions A and B, respectively, of mixed salts of nickel, cobalt and M, where M is Mn and / or Al; wherein salt solution A is a high-nickel, low-cobalt, low-M ratio, and salt solution B is a low-nickel, high-cobalt, high-M ratio; (2) Salt solution A, salt solution B, precipitant and complexing agent are fed into the bottom liquid of the reactor in a co-precipitation reaction under an inert atmosphere. During the feeding process, while maintaining the total feed flow rate increasing, the flow rate ratio of salt solution A to salt solution B is linearly adjusted to gradually increase the proportion of salt solution A and decrease the proportion of salt solution B. The feed flow rates of precipitant and complexing agent are adjusted in real time according to the pH value and ammonia concentration of the reaction system. The coprecipitation reaction includes a first stage and a second stage. In the first stage after feeding begins, the pH of the reaction system is periodically increased slightly in stages, with an increase of 0.2~0.3. After each increase, the pH is stabilized for a certain period of time before being lowered back to the initial average value. The generation of new nuclei is induced by pH fluctuations, and the amount of new nuclei generated each time is controlled to be 3~5wt% of the current solid content. After the new nuclei are generated, they enter the synchronous growth stage and grow together with the existing crystal nuclei in the system. Throughout the reaction process, the average pH value, ammonia concentration, temperature and stirring speed of the system are kept stable, with the average pH value being 11.6~12.0 and the ammonia concentration being 3.5~4.8g / L. In the second stage, the pH fluctuation operation is stopped, and the average pH fluctuation range, ammonia concentration fluctuation range, and temperature fluctuation range of the reaction system are kept within the set range. The feeding reaction continues until the total reaction time ends. (3) Stop feeding, maintain the temperature and stirring speed of the reaction system for aging, and then the aged material is separated into solid and liquid, washed and dried to obtain a ternary precursor with a wide particle size distribution.

[0008] Thirdly, a ternary cathode material is provided, which is obtained by sintering the wide-particle-size ternary precursor described in the first aspect with a lithium source, optional dopants, and additives; or by sintering the wide-particle-size ternary precursor prepared by the preparation method described in the second aspect with a lithium source, optional dopants, and additives.

[0009] Fourthly, a battery is provided, comprising the ternary cathode material described in the third aspect.

[0010] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects: 1. The provided ternary precursor has good processing performance, and the spherical or near-spherical shape gives it excellent flowability and dispersibility; the particle size distribution curve has no bimodal or multimodal characteristics, and the diameter is controlled between 1.0 and 1.3, which not only ensures the particle size distribution effect to improve compaction density, but also avoids the sintering performance mismatch problem caused by multimodal distribution.

[0011] 2. The provided ternary precursor exhibits nickel content and primary particle size that increase with increasing particle size. Small particles with low nickel content ensure sintering activity, while large particles with high nickel content enhance energy density, thus rationally matching the performance requirements of particles with different sizes. Each particle is nickel-poor at the center and nickel-rich at the surface; the nickel-rich surface provides increased output capacity, while the nickel-poor center suppresses cyclic microcracks. These two aspects work synergistically to achieve high energy density, long cycle life, and high voltage stability. Appropriate amounts of Co / Mn / Al stabilize the layered structure, suppress harmful phase transformations, and improve thermal safety and structural integrity.

[0012] 3. All precursor particles grow homogeneously in situ within a single reaction system without any physical mixing steps. There are no interfacial differences between particles, and the difference in thermal expansion coefficient is ≤1.5%, which completely solves the industry pain point of particle cracking during the circulation of the mixed system.

[0013] 4. The compaction density of the cathode material obtained after sintering the precursor of the present invention can reach 3.75 g / cm³. 3 The assembled button cell exhibits excellent high-temperature cycling performance, maintaining a capacity retention rate of over 85% after 1000 cycles at 45°C using 1C. Its overall performance is significantly superior to existing wide-distribution products. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1SEM image of the wide-particle-size ternary precursor prepared in Example 1.

[0016] Figure 2 The volume distribution particle size curve of the ternary precursor with a wide particle size distribution prepared in Example 1 is shown.

[0017] Figure 3 SEM image of small-diameter precursor particles in the ternary precursor prepared in Example 1.

[0018] Figure 4 SEM image of medium-sized precursor particles in the ternary precursor prepared in Example 1.

[0019] Figure 5 The image shows a SEM image of the large-diameter precursor particles in the ternary precursor prepared in Example 1.

[0020] Figure 6 The volume distribution particle size curve of the ternary precursor with a wide particle size distribution prepared for Comparative Example 1 is shown. Detailed Implementation

[0021] A typical embodiment of the present invention provides a ternary precursor with a wide particle size distribution, wherein the ternary precursor is a spherical or near-spherical secondary particle with the chemical formula Ni. x Co y M z (OH)2, where M is Mn and / or Al, x+y+z=1, 0.80≤x≤0.98, 0.01≤y≤0.20, 0.01≤z≤0.20; and the secondary particles have the following particle size distribution characteristics: D0 is 3~5μm, D10 is 5~8μm, D50 is 10~13μm, D90 is 16~21μm, the diameter span is 1~1.3, and there is only one peak in the volume-based particle size distribution curve, without obvious bimodal or multimodal characteristics.

[0022] The provided ternary precursor with a wide particle size distribution, featuring a medium particle size of 10-13 μm (D50), ensures good processing performance (not too fine, leading to dust; not too coarse, leading to coating difficulties) while being fully compatible with existing lithium battery production lines. The particle size distribution curve exhibits no bimodal or multimodal characteristics, with a wide distribution characteristic of 1.0-1.3 Span, guaranteeing the gradation and filling of secondary particles of varying sizes. Small particles (D10 approximately 5-8 μm) precisely fill the gaps between large particles (D90 approximately 16-21 μm), significantly reducing the porosity of the electrode sheet and increasing the compaction density to 3.6-3.9 g / cm³. 3Compared to conventional narrow-distribution products, this significantly improves the volumetric energy density of the battery, while avoiding the sintering performance mismatch problem caused by multi-peak distribution. The spherical or near-spherical secondary particle morphology endows the precursor with excellent flowability and dispersibility, enabling uniform spreading during electrode coating. Simultaneously, the spherical particles have the smallest specific surface area, effectively reducing side reactions between the electrode and electrolyte, and improving the battery's cycle stability. The chemical composition of the precursor ensures the high discharge specific capacity of the cathode material, meeting the core requirement of high energy density for lithium-ion batteries. Appropriate cobalt content stabilizes the layered structure, inhibits cation mixing, and reduces material costs. Moderate Mn and Al content provides structural support, suppresses harmful phase transitions during charge and discharge, and improves thermal stability and safety.

[0023] In some preferred embodiments, the secondary particles are formed by the aggregation of primary particles. As the particle size of the secondary particles increases, the length of the primary particles constituting the secondary particles also increases, meaning that the length of the primary particles is positively correlated with the particle size of the secondary particles. Large-sized secondary particles, composed of longer primary particles, have higher compressive strength and are less prone to breakage during high-density rolling. Small-sized secondary particles have shorter primary particle lengths and shorter lithium-ion diffusion paths, serving as fast-response units to improve rate performance. Large-sized secondary particles have relatively longer primary particle lengths and more complete crystallization, contributing significantly to capacity and ensuring long cycle life. Together, they achieve a unified rate and cycle life. Furthermore, the difference in primary particle size among secondary particles of different sizes leads to a more consistent lithiation reaction rate, effectively avoiding the process problems of over-burning small particles and under-burning large particles, widening the sintering process window, and improving product consistency and yield. This positive correlation also demonstrates the precise control capability of the co-precipitation process, representing a structural characteristic of the product's high consistency.

[0024] In some preferred embodiments, the length of the primary particle increases from 300 nm to 600 nm, from the smallest secondary particle to the largest secondary particle.

[0025] In some preferred embodiments, the value of x is 0.85≤x≤0.95; the value of y is 0.03≤y≤0.15; M is Mn; and the value of z is 0.02≤z≤0.05.

[0026] In some preferred embodiments, the molar content of nickel in any two secondary particles of different sizes exhibits a positive correlation with the particle size. The precursor achieves a gradient distribution of nickel-poor particles (small particles) and nickel-rich particles (large particles) in terms of composition. Because divalent nickel ions are difficult to oxidize, require more precise process control, and are more prone to structural defects, small particles with low nickel content exhibit better sintering activity, ensuring sintering activity. Large particles with high nickel content improve energy density, bringing the following advantages to the cathode material: the small particle nickel-poor region has high crystallinity and strong strain resistance, suppressing cycle microcracks and exhibiting good structural stability; the large particle nickel-rich region provides high specific capacity, enabling good capacity output; a gradual transition of nickel content from the particle surface to the interior avoids lattice mismatch and internal stress accumulation caused by abrupt compositional changes, effectively achieving stress buffering. The synergy of these three factors allows the battery to maintain excellent cycle stability at high voltages, while simultaneously achieving high energy density and long lifespan. Preferably, from the smallest to the largest secondary particle, the molar content of nickel gradually increases from 85% to 95%, while the total molar content of cobalt and M gradually decreases from 25% to 5%.

[0027] In some preferred embodiments, within a single secondary particle, the molar content of nickel gradually increases from the particle center to the particle surface. This creates a gradient structure within the individual secondary particle, characterized by a nickel-poor center and a nickel-rich surface, which provides the following advantages for the cathode material: the nickel-rich surface layer provides high capacity output, the nickel-poor central region suppresses microcrack propagation during cycling, and alleviates internal stress caused by lattice mismatch, significantly improving cycling stability and structural integrity under high voltage.

[0028] In some preferred embodiments, the difference in the coefficient of thermal expansion between any two secondary particles of different sizes in the ternary precursor is ≤1.5%. This low difference in the coefficient of thermal expansion ensures highly synchronized volume changes of particles of different sizes during charging and discharging, avoiding contact failures between particles, microcrack formation, and internal short circuit risks caused by expansion mismatch, thereby significantly extending battery cycle life and improving safety.

[0029] In some preferred embodiments, secondary particles of different sizes grow in the same environment, and there are no interfacial differences caused by physical mixing between the secondary particles. This characteristic of secondary particles ensures that all particles grow continuously under the same process conditions, fundamentally avoiding interfacial differences and performance inconsistencies between particles caused by physical mixing. This results in highly uniform particle size distribution, elemental composition, and electrochemical behavior within and between precursor batches, significantly improving the stability of electrode processing and the consistency of the final battery.

[0030] Another typical embodiment of the present invention provides a method for preparing a ternary precursor with a wide particle size distribution, comprising: (1) Prepare salt solutions A and B, which are mixed salts of nickel, cobalt and M, respectively, where M is Mn and / or Al; wherein salt solution A is a high-nickel, low-cobalt, low-M ratio, and salt solution B is a low-nickel, high-cobalt, high-M ratio, and there is a difference in the nickel content between the two solutions; (2) Salt solution A, salt solution B, precipitant and complexing agent are fed into the bottom liquid of the reactor in parallel flow, and a co-precipitation reaction is carried out under an inert atmosphere. During the feeding process, while the total feed flow rate is continuously increased, the flow ratio of salt solution A and salt solution B is linearly adjusted to gradually increase the proportion of salt solution A and decrease the proportion of salt solution B. The feed flow rates of precipitant and complexing agent are adjusted in real time according to the pH value and ammonia concentration of the reaction system. Through the linear adjustment of the flow rates of the two solutions, the nickel content in the reaction system is gradually increased. The coprecipitation reaction includes a first stage and a second stage; In the first stage after the feed begins, the pH of the reaction system is periodically increased slightly in stages, with an increase of 0.2~0.3. After each increase, the pH is stabilized for a certain period of time before being returned to the initial average value. The pH fluctuations induce the generation of new nuclei. After the new nuclei are generated, they enter the synchronous growth stage and grow together with the existing crystal nuclei in the system. Throughout the reaction process, the average pH value, ammonia concentration, temperature and stirring speed of the system are kept stable, with an average pH value of 11.6~12.0 and an ammonia concentration of 3.5~4.8 g / L. In the second stage, the pH fluctuation operation is stopped, and the average pH fluctuation range, ammonia concentration fluctuation range, and temperature fluctuation range of the reaction system are kept within the set range. The feeding reaction continues until the total reaction time ends. During this process, the different batches of crystal nuclei generated in the early stage grow synchronously and continuously, and the nickel content increases synchronously with the particle growth, eventually forming precursor particles with a single peak, continuous wide particle size distribution. (3) Stop feeding, maintain the temperature and stirring speed of the reaction system for aging, and then the aged material is separated into solid and liquid, washed and dried to obtain a ternary precursor with a wide particle size distribution.

[0031] In some preferred embodiments, the molar ratio of nickel, cobalt, and M in the salt solution A is (0.95~0.99):(0.005~0.03):(0.005~0.03); and the total metal concentration of the salt solution A is 1.8~2.2 mol / L.

[0032] In some preferred embodiments, the molar ratio of nickel, cobalt, and M in the salt solution B is (0.75~0.85):(0.10~0.20):(0.03~0.08); and the total metal concentration of the salt solution B is 1.8~2.2 mol / L.

[0033] In some embodiments, the precipitant is a sodium hydroxide solution; the concentration of the precipitant is 4~6 mol / L.

[0034] In some embodiments, the complexing agent is an aqueous ammonia solution; the concentration of the complexing agent is 8~12 mol / L.

[0035] In some preferred embodiments, the bottom liquid of the reaction vessel is an aqueous solution; the ammonia concentration of the bottom liquid is 3.5~4.8 g / L; the pH of the bottom liquid is 11.6~12.0; and the temperature of the bottom liquid is 50~60℃.

[0036] In some preferred embodiments, the amount of the bottom liquid in the reactor is 0.3 to 0.5 times the total volume of the reactor.

[0037] In some embodiments, the reaction vessel can be prepared as follows: pure water is added to the reaction vessel, heated to the reaction temperature under an inert atmosphere, a complexing agent is added to adjust the ammonia concentration of the bottom liquid, and a precipitant is added to adjust the pH value of the bottom liquid.

[0038] In some preferred embodiments, in step (2), the flow rates of salt solution A and salt solution B during the initial feeding are 1:3 to 5, for example, 1:3, 1:4, 1:5, etc.

[0039] In some preferred embodiments, in step (2), the total initial feed flow rate of salt solution A and salt solution B is (0.016~0.024)V / h, for example 0.016V / h, 0.018V / h, 0.020V / h, 0.022V / h, 0.024V / h, where V is the volume of the reactor. Taking a 500L reactor as an example, the total initial feed flow rate of salt solution A and salt solution B is 8~12L / h.

[0040] In some preferred embodiments, in step (2), the total feed flow rate of salt solution A and salt solution B during the feeding process is continuously increased at a rate of (0.0004~0.001)V / h (e.g., 0.0004V / h, 0.0005V / h, 0.0006V / h, 0.0007V / h, 0.0008V / h, 0.0009V / h, 0.001V / h, etc.) until the reaction ends; V is the volume of the reactor, and taking a 500L reactor as an example, it is continuously increased at a rate of 0.2~0.5L / h.

[0041] In some preferred embodiments, in step (2), the total flow rate of salt solution A and salt solution B is stabilized at (0.03~0.04) V / h before the reaction ends, for example, 0.03V / h, 0.032V / h, 0.034V / h, 0.036V / h, 0.038V / h, 0.04V / h, etc., where V is the volume of the reactor. Taking a 500L reactor as an example, the total flow rate is stabilized at 15~20L / h.

[0042] In some preferred embodiments, in step (2), the flow ratio of salt solution A to salt solution B is 3~5:1 before the feeding ends.

[0043] In some preferred embodiments, in step (2), the nickel content in the reaction system is gradually increased from 85% to 95% by linearly adjusting the flow rates of salt solution A and salt solution B.

[0044] In some preferred embodiments, in step (2), the first stage (i.e., the parallel control stage of nucleation and growth) lasts for the first 24 to 30 hours after the start of feeding; in the first stage, the pH is adjusted slightly every 6 to 8 hours, with an adjustment range of 0.2 to 0.3, and after each adjustment, it is stabilized for 0.5 to 1 hour before returning to the initial value.

[0045] In some preferred embodiments, in step (2), the temperature of the system is maintained at 50~60℃ throughout the reaction process.

[0046] In some preferred embodiments, in step (2), the stirring speed is maintained at 350~480 rpm throughout the reaction process.

[0047] In some preferred embodiments, in step (2), during the second stage, the average pH fluctuation of the reaction system is controlled to be ≤0.1.

[0048] In some preferred embodiments, in step (2), during the second stage, the ammonia concentration fluctuation range of the reaction system is controlled to be ≤0.2g / L.

[0049] In some preferred embodiments, in step (2), during the second stage, the temperature fluctuation range of the reaction system is controlled to be ≤1℃.

[0050] In some preferred embodiments, in step (2), the second stage continues until the total reaction time is 36-48 hours.

[0051] In some preferred embodiments, the aging time in step (3) is 3 to 6 hours.

[0052] In some preferred embodiments, in step (3), the filtrate is washed until the conductivity is ≤100μS / cm.

[0053] In some preferred embodiments, in step (3), the drying is vacuum drying; the drying temperature is 100~130℃; and the drying time is 10~15h.

[0054] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0055] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0056] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0057] Example 1 The preparation steps of the unimodal continuous gradient wide-particle-size-distribution ternary precursor in this embodiment are as follows: (1) Preparation of base solution: Two nickel-cobalt-manganese mixed salt solutions were prepared respectively: Salt solution A was a high nickel and low cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.98:0.01:0.01 and a total metal concentration of 2.0 mol / L; Salt solution B was a low nickel and high cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.80:0.15:0.05 and a total metal concentration of 2.0 mol / L; a sodium hydroxide solution with a concentration of 5 mol / L was prepared as a precipitant; an ammonia solution with a concentration of 10 mol / L was prepared as a complexing agent; 200L of pure water was added to a 500L reactor as the base solution, nitrogen gas was introduced for protection, the reactor was heated to 55℃, an ammonia solution was added to adjust the ammonia concentration of the base solution to 4 g / L, a sodium hydroxide solution was added to adjust the pH of the base solution to 11.7, and the stirring speed was set to 400 rpm.

[0058] (2) Parallel gradient feeding setup: Salt solution A and salt solution B are fed simultaneously throughout the entire process, without any single solution feeding stage: Initially, the flow ratio of A to B is 1:4, and the total initial feed flow rate is 10 L / h; during the reaction, while maintaining a continuous increase in the total feed flow rate at a rate of 0.3 L / h, the flow ratio of A to B is linearly adjusted, gradually increasing the proportion of A and decreasing the proportion of B, until the flow ratio of A to B is adjusted to 4:1 before the end of the reaction, and the final total flow rate is stabilized at 18 L / h; the feed flow rates of the precipitant and complexing agent are adjusted in real time according to the pH and ammonia concentration of the reaction system to ensure the stability of system parameters. During the reaction, the overflow liquid from the reactor enters the concentration device for solid-liquid separation, the concentrated slurry is returned to the reactor to continue participating in the reaction, and the separated mother liquor is discharged from the system.

[0059] (3) Parallel control of nucleation and growth: After the reaction starts, dynamic nucleation and particle growth are carried out synchronously throughout the process, and there is no independent nucleation stage: During the first 24 hours of growth after the start of feeding, the pH is adjusted slightly every 6 hours, with an adjustment range of 0.25. After each adjustment, the pH is stabilized for 0.5 hours before being adjusted back to the set value of 11.7. The pH fluctuation induces the generation of new nuclei. After the new nuclei are generated, they immediately enter the synchronous growth stage and grow together with the existing crystal nuclei in the reaction system. Throughout the reaction process, the average pH of the system is maintained at 11.7, the ammonia concentration is 4 g / L, the temperature is 55℃, and the stirring speed is 400 rpm.

[0060] (4) Continuous growth stage: After 24 hours, stop the pH fluctuation operation, keep the average pH fluctuation range of the reaction system ≤0.08, the ammonia concentration fluctuation range ≤0.2g / L, and the temperature fluctuation range ≤1℃, and continue feeding the reaction until the total reaction time is 36 hours. During this process, the different batches of crystal nuclei generated in the early stage grow synchronously and continuously, and the nickel content increases synchronously with the particle growth, eventually forming precursor particles with a single peak continuous gradient and wide particle size distribution.

[0061] (5) Post-processing: Stop feeding, maintain the temperature and stirring speed of the reaction system, age for 5 hours, then release the slurry, filter, wash with deionized water until the conductivity of the filtrate is ≤100μS / cm, and vacuum dry at 120℃ for 12 hours to obtain the ternary precursor product. Its SEM image is shown below. Figure 1 As shown, by Figure 1 It can be seen that the ternary precursor obtained in this embodiment has a wide particle size distribution.

[0062] Performance testing was performed on the product of this embodiment: D0=4.2μm, D10=6.8μm, D50=11.0μm, D90=20.0μm, Span=1.20. The particle size distribution exhibits a unimodal continuous distribution. The volume distribution particle size curve is shown in the figure below. Figure 2 As shown, the smallest particle has a nickel content of 81.2%, and the largest particle has a nickel content of 94.6%. The nickel content increases with the increase of the secondary particle size.

[0063] Figure 3 , Figure 4 and Figure 5 The images show SEM images of small, medium, and large particles of the nickel-cobalt-manganese ternary precursor obtained in Example 1. Figures 3-5 It can be seen that the primary particle size of the precursor increases with the increase of the secondary particle size. The average length of the smallest primary particle is 320 nm, and the average length of the largest primary particle is 580 nm. That is, the length of the primary particle is positively correlated with the secondary particle size, meaning that the length of the primary particle increases with the increase of the secondary particle size. The difference in the coefficient of thermal expansion of the precursor was measured to be 1.2%.

[0064] In this embodiment, the precursor and lithium salt LiOH were mixed at a lithium molar ratio of 1.03:1, and the mixture was heated at 550°C for 5 hours in an oxygen atmosphere, and then heated at 750°C for 15 hours to prepare the cathode material by sintering.

[0065] The compaction density of the obtained cathode material is 3.82 g / cm³. 3 At 45°C, the capacity retention rate after 1000 cycles at 1C was 89.3%.

[0066] Example 2 The difference between this embodiment and Example 1 is as follows: the pH of the base solution was adjusted to 11.9, the ammonia concentration to 4.5 g / L, the temperature to 58°C, and the stirring speed to 450 rpm; the initial total feed flow rate during the parallel feeding stage was 11 L / h, the flow rate increase rate was 0.35 L / h, and the final total flow rate stabilized at 19 L / h; the pH was increased by 0.22 every 7 hours during the first 28 hours of the nucleation and growth control stage; the pH fluctuation range during the continuous growth stage was 0.09, and the total reaction time was 48 hours. The resulting precursor product was obtained.

[0067] Performance testing was conducted on the product of this embodiment: D0=5.0μm, D10=7.5μm, D50=12.0μm, D90=17.6μm, Span=1.05, and the particle size distribution exhibits a unimodal continuous distribution; the smallest particle has a nickel content of 83%, and the largest particle has a nickel content of 94.7%, with the nickel content increasing with the increase of secondary particle size; the length of the smallest primary particle is 350nm, and the length of the largest primary particle is 590nm, indicating a positive correlation between the length of the primary particle and the particle size of the secondary particle, meaning that the length of the primary particle increases with the increase of the secondary particle size; the difference in the coefficient of thermal expansion is 1.3%.

[0068] In this embodiment, the precursor and lithium salt LiOH were mixed at a lithium molar ratio of 1.03:1, and the mixture was heated at 550°C for 5 hours in an oxygen atmosphere, and then heated at 750°C for 15 hours. The mixture was then sintered to prepare the cathode material.

[0069] The compaction density of the obtained cathode material is 3.80 g / cm³. 3 At 45°C, the capacity retention rate was 88.5% after 1000 cycles at 1C.

[0070] Example 3 The preparation steps of the unimodal continuous gradient wide-particle-size-distribution ternary precursor in this embodiment are as follows: (1) Preparation of base solution: Two nickel-cobalt-manganese mixed salt solutions were prepared respectively: Salt solution A was a high nickel and low cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.98:0.01:0.01 and a total metal concentration of 2.0 mol / L; Salt solution B was a low nickel and high cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.80:0.15:0.05 and a total metal concentration of 2.0 mol / L; a sodium hydroxide solution with a concentration of 5 mol / L was prepared as a precipitant; an ammonia solution with a concentration of 10 mol / L was prepared as a complexing agent; 200L of pure water was added to a 500L reactor as the base solution, nitrogen gas was introduced for protection, the reactor was heated to 55℃, an ammonia solution was added to adjust the ammonia concentration of the base solution to 4 g / L, a sodium hydroxide solution was added to adjust the pH of the base solution to 11.7, and the stirring speed was set to 400 rpm.

[0071] (2) Parallel gradient feeding setup: Salt solution A and salt solution B are fed simultaneously throughout the entire process, without any single solution feeding stage: Initially, the flow ratio of A to B is 1:3, and the total initial feed flow rate is 10 L / h; during the reaction, while maintaining a continuous increase in the total feed flow rate at a rate of 0.3 L / h, the flow ratio of A to B is linearly adjusted, gradually increasing the proportion of A and decreasing the proportion of B, until the flow ratio of A to B is adjusted to 3:1 before the end of the reaction, and the final total flow rate is stabilized at 18 L / h; the feed flow rates of the precipitant and complexing agent are adjusted in real time according to the pH and ammonia concentration of the reaction system to ensure the stability of system parameters. During the reaction, the overflow liquid from the reactor enters the concentration device for solid-liquid separation, the concentrated slurry is returned to the reactor to continue participating in the reaction, and the separated mother liquor is discharged from the system.

[0072] (3) Parallel control of nucleation and growth: After the reaction starts, dynamic nucleation and particle growth are carried out synchronously throughout the process, and there is no independent nucleation stage: During the first 24 hours of growth after the start of feeding, the pH is adjusted slightly every 6 hours, with an adjustment range of 0.25. After each adjustment, the pH is stabilized for 0.6 hours before being adjusted back to the set value of 11.7. The pH fluctuation induces the generation of new nuclei. After the new nuclei are generated, they immediately enter the synchronous growth stage and grow together with the existing crystal nuclei in the reaction system. Throughout the reaction process, the average pH of the system is maintained at 11.7, the ammonia concentration is 4 g / L, the temperature is 55℃, and the stirring speed is 400 rpm.

[0073] (4) Continuous growth stage: After 24 hours, stop the pH fluctuation operation, keep the average pH fluctuation range of the reaction system ≤0.08, the ammonia concentration fluctuation range ≤0.2g / L, and the temperature fluctuation range ≤1℃, and continue feeding the reaction until the total reaction time is 36 hours. During this process, the different batches of crystal nuclei generated in the early stage grow synchronously and continuously, and the nickel content increases synchronously with the particle growth, eventually forming precursor particles with a single peak continuous gradient and wide particle size distribution.

[0074] (5) Post-processing: Stop feeding, maintain the temperature and stirring speed of the reaction system, age for 5 hours, release the slurry, filter, wash with deionized water until the conductivity of the filtrate is ≤100μS / cm, vacuum dry at 120℃ for 12 hours to obtain the ternary precursor product.

[0075] The performance of the product in this embodiment was tested: D50 was 10.5μm, Span=1.1, and the particle size distribution showed a unimodal continuous distribution; the nickel content increased from the smallest to the largest particle size, that is, the nickel content increased with the increase of the secondary particles, and the two showed a positive correlation; the difference in the coefficient of thermal expansion was 1.5%.

[0076] The obtained ternary precursor was used to prepare a cathode material, using the same preparation process as in Example 1. Characterization of the cathode material revealed a compaction density of 3.75 g / cm³. 3 At 45°C, the capacity retention rate after 1000 cycles at 1C was 86.0%.

[0077] Example 4 The preparation steps of the unimodal continuous gradient wide-particle-size-distribution ternary precursor in this embodiment are as follows: (1) Preparation of base solution: Two nickel-cobalt-manganese mixed salt solutions were prepared respectively: Salt solution A was a high nickel and low cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.98:0.01:0.01 and a total metal concentration of 2.0 mol / L; Salt solution B was a low nickel and high cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.80:0.15:0.05 and a total metal concentration of 2.0 mol / L; a sodium hydroxide solution with a concentration of 5 mol / L was prepared as a precipitant; an ammonia solution with a concentration of 10 mol / L was prepared as a complexing agent; 200L of pure water was added to a 500L reactor as the base solution, nitrogen gas was introduced for protection, the reactor was heated to 52℃, an ammonia solution was added to adjust the ammonia concentration of the base solution to 3.5 g / L, a sodium hydroxide solution was added to adjust the pH of the base solution to 11.6, and the stirring speed was set to 350 rpm.

[0078] (2) Parallel gradient feeding setup: Salt solution A and salt solution B are fed simultaneously throughout the entire process, without any single solution feeding stage: Initially, the flow ratio of A to B is 1:5, and the total initial feed flow rate is 8 L / h; during the reaction, while maintaining a continuous increase in the total feed flow rate at a rate of 0.2 L / h, the flow ratio of A to B is linearly adjusted, gradually increasing the proportion of A and decreasing the proportion of B, until the flow ratio of A to B is adjusted to 5:1 before the end of the reaction, and the final total flow rate is stabilized at 15 L / h; the feed flow rates of the precipitant and complexing agent are adjusted in real time according to the pH and ammonia concentration of the reaction system to ensure the stability of system parameters. During the reaction, the overflow liquid from the reactor enters the concentration device for solid-liquid separation, the concentrated slurry is returned to the reactor to continue participating in the reaction, and the separated mother liquor is discharged from the system.

[0079] (3) Parallel control of nucleation and growth: After the reaction starts, dynamic nucleation and particle growth are carried out synchronously throughout the process, and there is no independent nucleation stage: During the first 24 hours of growth after the start of feeding, the pH is adjusted slightly every 6 hours, with an adjustment range of 0.3. After each adjustment, the pH is stabilized for 1 hour before being adjusted back to the set value of 11.6. The pH fluctuation induces the generation of new nuclei. After the new nuclei are generated, they immediately enter the synchronous growth stage and grow together with the existing crystal nuclei in the reaction system. Throughout the reaction process, the average pH of the system is maintained at 11.6, the ammonia concentration is 3.5 g / L, the temperature is 52℃, and the stirring speed is 350 rpm.

[0080] (4) Continuous growth stage: After 24 hours, stop the pH fluctuation operation, keep the average pH fluctuation range of the reaction system ≤0.08, the ammonia concentration fluctuation range ≤0.2g / L, and the temperature fluctuation range ≤1℃, and continue feeding the reaction until the total reaction time is 36 hours. During this process, the different batches of crystal nuclei generated in the early stage grow synchronously and continuously, and the nickel content increases synchronously with the particle growth, eventually forming precursor particles with a single peak continuous gradient and wide particle size distribution.

[0081] (5) Post-processing: Stop feeding, maintain the temperature and stirring speed of the reaction system, age for 5 hours, release the slurry, filter, wash with deionized water until the conductivity of the filtrate is ≤100μS / cm, vacuum dry at 120℃ for 12 hours to obtain the ternary precursor product.

[0082] The performance of the precursor product in this embodiment was tested: D50 was 9 μm, Span was 1.18, and the particle size distribution showed a unimodal continuous distribution; the nickel content increased continuously from the smallest to the largest particle size, that is, the nickel content increased with the increase of the secondary particles, and the two showed a positive correlation; the difference in the coefficient of thermal expansion was 1.4%.

[0083] The obtained ternary precursor was used to prepare a cathode material, using the same preparation process as in Example 1. The cathode material was characterized, and its compaction density was found to be 3.81 g / cm³. 3 At 45°C, the capacity retention rate was 87.7% after 1000 cycles at 1C.

[0084] Example 5 The preparation steps of the unimodal continuous gradient wide-particle-size-distribution ternary precursor in this embodiment are as follows: (1) Preparation of base solution: Two nickel-cobalt-manganese mixed salt solutions were prepared respectively: Salt solution A was a high nickel and low cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.98:0.01:0.01 and a total metal concentration of 2.0 mol / L; Salt solution B was a low nickel and high cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.80:0.15:0.05 and a total metal concentration of 2.0 mol / L; a sodium hydroxide solution with a concentration of 5 mol / L was prepared as a precipitant; an ammonia solution with a concentration of 10 mol / L was prepared as a complexing agent; 200L of pure water was added to a 500L reactor as the base solution, nitrogen gas was introduced for protection, the reactor was heated to 55℃, an ammonia solution was added to adjust the ammonia concentration of the base solution to 4.8 g / L, a sodium hydroxide solution was added to adjust the pH of the base solution to 12, and the stirring speed was set to 480 rpm.

[0085] (2) Parallel gradient feeding setup: Salt solution A and salt solution B are fed simultaneously throughout the entire process, without any single solution feeding stage: Initially, the flow ratio of A to B is 1:3, and the total initial feed flow rate is 12 L / h; during the reaction, while maintaining the total feed flow rate at a rate of 0.5 L / h, the flow ratio of A to B is linearly adjusted, gradually increasing the proportion of A and decreasing the proportion of B, until the flow ratio of A to B is adjusted to 4:1 before the end of the reaction, and the final total flow rate is stabilized at 20 L / h; the feed flow rates of the precipitant and complexing agent are adjusted in real time according to the pH and ammonia concentration of the reaction system to ensure the stability of system parameters. During the reaction, the overflow liquid from the reactor enters the concentration device for solid-liquid separation, the concentrated slurry is returned to the reactor to continue participating in the reaction, and the separated mother liquor is discharged from the system.

[0086] (3) Parallel control of nucleation and growth: After the reaction starts, dynamic nucleation and particle growth are carried out synchronously throughout the process, and there is no independent nucleation stage: During the first 24 hours of growth after the start of feeding, the pH is adjusted slightly every 6 hours, with an adjustment range of 0.2. After each adjustment, the pH is stabilized for 0.5 hours before being adjusted back to the set value of 12. The pH fluctuation induces the generation of new nuclei. After the new nuclei are generated, they immediately enter the synchronous growth stage and grow together with the existing crystal nuclei in the reaction system. Throughout the reaction process, the average pH of the system is maintained at 12, the ammonia concentration is 4.8 g / L, the temperature is 55℃, and the stirring speed is 480 rpm.

[0087] (4) Continuous growth stage: After 24 hours, stop the pH fluctuation operation, keep the average pH fluctuation range of the reaction system ≤0.08, the ammonia concentration fluctuation range ≤0.2g / L, and the temperature fluctuation range ≤1℃, and continue feeding the reaction until the total reaction time is 36 hours. During this process, the different batches of crystal nuclei generated in the early stage grow synchronously and continuously, and the nickel content increases synchronously with the particle growth, eventually forming precursor particles with a single peak continuous gradient and wide particle size distribution.

[0088] (5) Post-processing: Stop feeding, maintain the temperature and stirring speed of the reaction system, age for 5 hours, release the slurry, filter, wash with deionized water until the conductivity of the filtrate is ≤100μS / cm, vacuum dry at 120℃ for 12 hours to obtain the ternary precursor product.

[0089] The performance of the precursor product in this embodiment was tested: D50 was 13.5 μm, Span was 1.25, and the particle size distribution showed a unimodal continuous distribution; the nickel content increased from the smallest to the largest particle size, that is, the nickel content increased with the increase of the secondary particles, and the two showed a positive correlation; the difference in the coefficient of thermal expansion was 1.3%.

[0090] The obtained ternary precursor was used to prepare a cathode material, using the same preparation process as in Example 1. Characterization of the cathode material revealed a compaction density of 3.79 g / cm³. 3 At 45°C, the capacity retention rate was 88.1% after 1000 cycles at 1C.

[0091] Comparative Example 1 In this comparative example, a broad-distribution precursor was prepared using a conventional physical blending method. Two narrow-distribution precursors with D50=5μm and D50=16μm were mixed at a mass ratio of 3:7, resulting in a product with D50=11.0μm and Span=1.31.

[0092] The performance of the mixed precursor products of this comparative example was tested. The particle size distribution showed a bimodal continuous distribution, and the volume distribution particle size curve is shown in the figure below. Figure 6 As shown, there is no necessary correlation between the Ni content of the precursor particles and the size of the secondary particles. The difference in nickel content between particles of different sizes is 12%, showing a significant abrupt change. The difference in the coefficient of thermal expansion is 4.5%.

[0093] The obtained precursor and lithium salt LiOH were mixed at a lithium molar ratio of 1.03:1, and the mixture was heated at 550℃ for 5 hours in an oxygen atmosphere, and then heated at 750℃ for 15 hours. The mixture was then sintered to prepare the cathode material.

[0094] The obtained cathode material has a cathode compaction density of 3.65 g / cm³. 3 At 45°C, the capacity retention rate after 1000 cycles at 1C was 78.6%.

[0095] Comparative Example 2 This comparative example uses an intermittent seeding method to prepare a broadly distributed precursor, with seed crystals added at 7, 14, and 21 hours during the reaction. Specifically: (1) Preparation of base solution: Two nickel-cobalt-manganese mixed salt solutions were prepared respectively: Salt solution A was a high nickel and low cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.98:0.01:0.01 and a total metal concentration of 2.0 mol / L; Salt solution B was a low nickel and high cobalt-manganese ratio, with a molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 0.80:0.15:0.05 and a total metal concentration of 2.0 mol / L; a sodium hydroxide solution with a concentration of 5 mol / L was prepared as a precipitant; an ammonia solution with a concentration of 10 mol / L was prepared as a complexing agent; 200L of pure water was added to a 500L reactor as the base solution, nitrogen gas was introduced for protection, the reactor was heated to 55℃, an ammonia solution was added to adjust the ammonia concentration of the base solution to 4 g / L, a sodium hydroxide solution was added to adjust the pH of the base solution to 11.7, and the stirring speed was set to 400 rpm.

[0096] (2) Parallel gradient feeding setup: Salt solution A and salt solution B are fed simultaneously throughout the entire process, without any single solution feeding stage: Initially, the flow ratio of A to B is 1:4, and the total initial feed flow rate is 10 L / h; during the reaction, while maintaining a continuous increase in the total feed flow rate at a rate of 0.3 L / h, the flow ratio of A to B is linearly adjusted, gradually increasing the proportion of A and decreasing the proportion of B, until the flow ratio of A to B is adjusted to 4:1 before the end of the reaction, and the final total flow rate is stabilized at 18 L / h; the feed flow rates of the precipitant and complexing agent are adjusted in real time according to the pH and ammonia concentration of the reaction system to ensure the stability of system parameters. During the reaction, the overflow liquid from the reactor enters the concentration device for solid-liquid separation, the concentrated slurry is returned to the reactor to continue participating in the reaction, and the separated mother liquor is discharged from the system.

[0097] (3) Parallel control of nucleation and growth: During the entire reaction process, the average pH of the system was maintained at 11.7, the ammonia concentration at 4 g / L, the temperature at 55℃, and the stirring speed at 400 rpm. At the 7h, 14h, and 21h of the reaction, 4.5% of the current solid content and 5μm of seed crystals were added to the reaction system. The average pH fluctuation range of the reaction system was maintained at ≤0.08, the ammonia concentration fluctuation range at ≤0.2 g / L, and the temperature fluctuation range at ≤1℃. The reaction was continued until the total reaction time was 36h.

[0098] (4) Post-processing: Stop feeding, maintain the temperature and stirring speed of the reaction system, age for 5 hours, release the slurry, filter, wash with deionized water until the conductivity of the filtrate is ≤100μS / cm, vacuum dry at 120℃ for 12 hours to obtain the ternary precursor product.

[0099] The obtained product particle size distribution exhibits a trimodal characteristic, with D50=11.6μm and Span=1.51; the nickel content of particles with different sizes differs by 12%, and the Ni content of the precursor particles is not completely proportional to the size of the secondary particles, showing a significant abrupt change; the difference in thermal expansion coefficient is 3.8%.

[0100] The obtained precursor and lithium salt LiOH were mixed at a lithium molar ratio of 1.03:1, and the mixture was heated at 550℃ for 5 hours in an oxygen atmosphere, and then heated at 750℃ for 15 hours. The mixture was then sintered to prepare the cathode material.

[0101] The obtained cathode material has a cathode compaction density of 3.70 g / cm³. 3 At 45°C, the capacity retention rate after 1000 cycles at 1C was 75.3%.

[0102] Comparative Example 3 The only difference between this comparative example and Example 1 is that in step (3), the pH is increased by a different amount each time, with an increase of 0.5, inducing the generation of new nuclei through pH fluctuations.

[0103] Performance tests were conducted on the precursor products of this comparative example: D50 was 10 μm, Span was 1.33, and the particle size distribution showed a bimodal distribution; the Ni content of the precursor particles was not directly proportional to the size of the secondary particles, and there was an obvious abrupt change; the difference in the coefficient of thermal expansion was 4.0%.

[0104] The obtained ternary precursor was used to prepare a cathode material, using the same preparation process as in Example 1. The cathode material had a compaction density of 3.72 g / cm³. 3 At 45°C, the capacity retention rate was 80.0% after 1000 cycles at 1C.

[0105] Comparative Example 4 The only difference between this comparative example and Example 1 is that in step (3), the pH is increased by a different amount each time, with an increase of 0.1, inducing the generation of new nuclei through pH fluctuations.

[0106] Performance tests were conducted on the precursor products of this comparative example: D50 was 11.5 μm, Span was 1.40, and the particle size distribution showed a bimodal distribution; the Ni content of the precursor particles was not directly proportional to the size of the secondary particles, and there was an obvious abrupt change; the difference in the coefficient of thermal expansion was 3.3%.

[0107] The obtained ternary precursor was used to prepare a cathode material, using the same preparation process as in Example 1. Characterization of the cathode material revealed a cathode compaction density of 3.66 g / cm³. 3 At 45°C, the capacity retention rate after 1000 cycles at 1C was 79.6%.

[0108] Comparative Example 5 The only difference between this comparative example and Example 1 is that in step (1), the pH value of the base liquid is 11; in step (2), the pH value of the system is ensured to be 11; and in step (3), the average pH value of the system is maintained at 11 throughout the reaction process.

[0109] Performance tests were conducted on the precursor products of this comparative example: D50 was 9.5 μm, Span was 1.35, and the particle size distribution showed a bimodal distribution; the Ni content of the precursor particles was not directly proportional to the size of the secondary particles, and there was an obvious abrupt change; the difference in the coefficient of thermal expansion was 3.7%.

[0110] The obtained ternary precursor was used to prepare a cathode material, using the same preparation process as in Example 1. Characterization of the cathode material revealed a cathode compaction density of 3.60 g / cm³. 3 At 45°C, the capacity retention rate after 1000 cycles at 1C was 77.2%.

[0111] Comparative Example 6 The only difference between this comparative example and Example 1 is that in step (1), an ammonia solution is added to adjust the ammonia concentration of the bottom liquid to 6.5 g / L; in step (2), the ammonia concentration of the system is ensured to be 6.5 g / L; and in step (3), the ammonia concentration of the system is maintained at approximately 6.5 g / L throughout the entire reaction process.

[0112] Performance tests were conducted on the precursor products of this comparative example: D50 was 12.5 μm, Span was 1.41, and the particle size distribution showed a bimodal distribution; the Ni content of the precursor particles was not directly proportional to the size of the secondary particles, and there was an obvious abrupt change; the difference in the coefficient of thermal expansion was 4.4%.

[0113] The obtained ternary precursor was used to prepare a cathode material, using the same preparation process as in Example 1. Characterization of the cathode material revealed a cathode compaction density of 3.67 g / cm³. 3 At 45°C, the capacity retention rate after 1000 cycles at 1C was 78.1%.

[0114] Comparative Example 7 The only difference between this comparative example and Example 1 is that, in step (2), the total flow rate of salt solution A and salt solution B remains unchanged, specifically including: Salt solutions A and B are fed simultaneously and in parallel throughout the entire process, without any single solution feeding stage: the initial feed flow ratio of A to B is 1:4, and the total initial feed flow rate is 10 L / h; during the reaction, the total feed flow rate is maintained, and the flow ratio of A to B is linearly adjusted, gradually increasing the proportion of A and decreasing the proportion of B, until the flow ratio of A to B is adjusted to 4:1 before the end of the reaction; the feed flow rates of the precipitant and complexing agent are adjusted in real time according to the pH and ammonia concentration of the reaction system to ensure the stability of system parameters.

[0115] Performance tests were conducted on the precursor products of this comparative example: D50 was 9.5 μm, Span=1.36, and the particle size distribution showed a bimodal distribution; the Ni content of the precursor particles was not directly proportional to the size of the secondary particles, and there was an obvious abrupt change; the difference in the coefficient of thermal expansion was 3.9%.

[0116] The obtained ternary precursor was used to prepare a cathode material, using the same preparation process as in Example 1. Characterization of the cathode material revealed a cathode compaction density of 3.61 g / cm³. 3 At 45°C, the capacity retention rate after 1000 cycles at 1C was 77.9%.

[0117] Performance characterization methods: The compaction density was obtained using conventional compaction density testing methods under a pressure of 2.6t.

[0118] Particle size, span, and particle size distribution curves were obtained using a Malvern 3000 particle size analyzer.

[0119] The elemental distribution characteristics were determined using scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy.

[0120] The coefficient of thermal expansion was tested using a thermomechanical analyzer.

[0121] Coin cells were assembled using the standard assembly method for CR2032 coin cells, and the assembled coin cells were tested at a 1C rate and a voltage range of 2.8~4.25V.

[0122] The characterization parameters for the cathode material properties are shown in Table 1 below.

[0123] Table 1 As can be seen from the foregoing embodiments and comparative examples, the precursors prepared in each embodiment have a diameter spacing of 1.1~1.3 and a single-peak continuous distribution, with the difference in the dimensional thermal expansion coefficient of nickel content in the precursors not exceeding 1.5%; and the corresponding cathode materials prepared have high compaction density, not less than 3.7 g / cm³. 3 It has excellent high-temperature cycling performance.

[0124] Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that Example 1, through dynamic pH fluctuation-induced continuous nucleation, gradient feeding throughout the process, and strict control of process condition fluctuations, achieved parallel control of particle growth and nucleation, ultimately forming a single-peak continuous gradient wide distribution. The nickel content increases with the increase of secondary lithium particle size, and the primary particle size also increases with the increase of secondary particle size. The thermal expansion difference is small, and the resulting precursor has a wide and continuous particle size distribution with an increasing compositional gradient. The compaction density and cycle retention rate of the cathode material after sintering are significantly better than the two comparative examples. Comparative Example 1 uses physical mixing of precursors with different narrow particle sizes, resulting in a bimodal distribution. The nickel content is not necessarily related to the particle size and exhibits abrupt changes, with significant differences in thermal expansion. Comparative Example 2 uses intermittent external seeding, resulting in a wide distribution but with multi-peak characteristics. The nickel content changes without a clear pattern, and the thermal expansion difference is large.

[0125] Comparing Example 1 with Comparative Examples 3-7, it can be seen that pH value, ammonia concentration, pH up-adjustment range, salt flow rate, etc., can all affect the physical properties and composition of the precursor, thereby adversely affecting the high-temperature cycling performance of the cathode material.

[0126] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A ternary precursor with a wide particle size distribution, characterized in that, The ternary precursor is a spherical or near-spherical secondary particle with the chemical formula Ni. x Co y M z (OH)2, where M is Mn and / or Al, x+y+z=1, 0.80≤x≤0.98, 0.01≤y≤0.20, 0.01≤z≤0.20; the secondary particles have the following particle size distribution characteristics: D0 is 3~5μm, D10 is 5~8μm, D50 is 10~13μm, D90 is 16~21μm, the radial span is 1~1.3, and there is only one peak in the volume-based particle size distribution curve.

2. The ternary precursor with wide particle size distribution as described in claim 1, characterized in that, The secondary particles are formed by the aggregation of primary particles. As the particle size of the secondary particles increases, the length of the primary particles constituting the secondary particles gradually increases. And / or, from the smallest secondary particle to the largest secondary particle, the length of the primary particle increases from 300 nm to 600 nm; And / or, the value of x is 0.85 ≤ x ≤ 0.95; And / or, the value of y is 0.03 ≤ y ≤ 0.15; And / or, M is Mn; And / or, the value of z is 0.02≤z≤0.

05.

3. The ternary precursor with wide particle size distribution as described in claim 1, characterized in that, The molar content of nickel in any two secondary particles with different sizes shows a positive correlation with the particle size of the secondary particles. And / or, within a single secondary particle, the molar content of nickel gradually increases from the particle center to the particle surface; And / or, in the ternary precursor, the difference in the coefficient of thermal expansion between any two secondary particles of different sizes is ≤1.5%; And / or, the growth environment of secondary particles of different sizes is homologous, and there are no interface differences caused by physical mixing between secondary particles.

4. A method for preparing a ternary precursor with a wide particle size distribution, characterized in that, include: (1) Prepare salt solutions A and B, respectively, of mixed salts of nickel, cobalt and M, where M is Mn and / or Al; wherein salt solution A is a high-nickel, low-cobalt, low-M ratio, and salt solution B is a low-nickel, high-cobalt, high-M ratio; (2) Salt solution A, salt solution B, precipitant and complexing agent are fed into the bottom liquid of the reactor in a co-precipitation reaction under an inert atmosphere. During the feeding process, while maintaining the total feed flow rate increasing, the flow rate ratio of salt solution A to salt solution B is linearly adjusted to gradually increase the proportion of salt solution A and decrease the proportion of salt solution B. The feed flow rates of precipitant and complexing agent are adjusted in real time according to the pH value and ammonia concentration of the reaction system. The coprecipitation reaction includes a first stage and a second stage. In the first stage after the feed begins, the pH of the reaction system is periodically increased slightly in stages, with an increase of 0.2~0.

3. After each increase, the pH is stabilized for a certain period of time before being returned to the initial average value of 11.6~12.

0. The pH fluctuations induce the generation of new nuclei. After the new nuclei are generated, they enter the synchronous growth stage and grow together with the existing crystal nuclei in the system. Throughout the reaction process, the average pH, ammonia concentration, temperature and stirring speed of the system are kept stable, with the average pH being 11.6~12.0 and the ammonia concentration being 3.5~4.8 g / L. In the second stage, the pH fluctuation operation is stopped, and the average pH fluctuation range, ammonia concentration fluctuation range, and temperature fluctuation range of the reaction system are kept within the set range. The feeding reaction continues until the total reaction time ends. (3) Stop feeding, maintain the temperature and stirring speed of the reaction system for aging, and then the aged material is separated into solid and liquid, washed and dried to obtain a ternary precursor with a wide particle size distribution.

5. The method for preparing a ternary precursor with a wide particle size distribution as described in claim 4, characterized in that, The molar ratio of nickel, cobalt, and M in the salt solution A is (0.95~0.99):(0.005~0.03):(0.005~0.03); the total metal concentration of the salt solution A is 1.8~2.2 mol / L. And / or, the molar ratio of nickel, cobalt, and M in the salt solution B is (0.75~0.85):(0.10~0.20):(0.03~0.08); the total metal concentration of the salt solution B is 1.8~2.2 mol / L; And / or, the precipitant is a sodium hydroxide solution; the concentration of the precipitant is 4~6 mol / L; And / or, the complexing agent is an aqueous ammonia solution; the concentration of the complexing agent is 8~12 mol / L; And / or, the bottom liquid of the reaction vessel is an aqueous solution; the ammonia concentration of the bottom liquid of the reaction vessel is 3.5~4.8 g / L; the pH of the bottom liquid of the reaction vessel is 11.6~12.0; and the temperature of the bottom liquid of the reaction vessel is 50~60℃. And / or, the amount of the bottom liquid in the reactor is 0.3 to 0.5 times the total volume of the reactor.

6. The method for preparing a ternary precursor with a wide particle size distribution as described in claim 4, characterized in that, In step (2), the flow rate ratio of salt solution A to salt solution B is 1:(3~5) during the initial feeding. And / or, in step (2), the total initial feed flow rate of salt solution A and salt solution B is (0.016~0.024)V / h, where V is the volume of the reactor; And / or, in step (2), the total feed flow rate of salt solution A and salt solution B during the feeding process is continuously increased at a rate of (0.0004~0.001)V / h, where V is the volume of the reactor; And / or, in step (2), the total flow rate of salt solution A and salt solution B is stabilized at (0.03~0.04) V / h before the reaction ends, where V is the volume of the reactor; And / or, in step (2), the flow rate ratio of salt solution A to salt solution B before the end of feeding is (3~5):1; And / or, in step (2), the nickel content in the reaction system is gradually increased from 85% to 95% by linearly adjusting the flow rates of salt solution A and salt solution B.

7. The method for preparing a ternary precursor with a wide particle size distribution as described in claim 4, characterized in that, In step (2), the first stage lasts for the first 24 to 30 hours after the start of feeding; during the first stage, the pH is adjusted slightly every 6 to 8 hours, with an adjustment range of 0.2 to 0.3, and after each adjustment, it is stabilized for 0.5 to 1 hour before returning to the initial value; And / or, in step (2), the temperature of the system is maintained at 50~60℃ throughout the reaction process; And / or, in step (2), the stirring speed is maintained at 350~480 rpm throughout the reaction process; And / or, in step (2), in the second stage, the average pH fluctuation of the reaction system is controlled to be ≤0.1; And / or, in step (2), in the second stage, the fluctuation range of ammonia concentration in the reaction system is controlled to be ≤0.2g / L; And / or, in step (2), in the second stage, the temperature fluctuation range of the reaction system is controlled to be ≤1℃; And / or, in step (2), the second stage continues until the total reaction time is 36~48h.

8. The method for preparing a ternary precursor with a wide particle size distribution as described in claim 4, characterized in that, In step (3), the aging time is 3~6 hours; And / or, in step (3), wash until the conductivity of the filtrate is ≤100μS / cm; And / or, in step (3), the drying is vacuum drying; the drying temperature is 100~130℃; and the drying time is 10~15h.

9. A ternary cathode material, characterized in that, The ternary precursor with wide particle size distribution as described in any one of claims 1 to 3 is obtained by sintering with a lithium source, optional dopant, and additive; or the ternary precursor with wide particle size distribution prepared by the preparation method described in any one of claims 4 to 8 is obtained by sintering with a lithium source, optional dopant, and additive.

10. A battery, characterized in that, Including the ternary cathode material as described in claim 9.

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