CN113387400B

CN113387400B - Continuous production method and device for in-situ doping of high-nickel ternary positive electrode material precursor of lithium ion battery

Info

Publication number: CN113387400B
Application number: CN202110580726.7A
Authority: CN
Inventors: 胡小萍; 周少雄
Original assignee: Jiangsu Jicui Antai Chuangming Advanced Energy Materials Research Institute Co ltd
Current assignee: Jiangsu Jicui Antai Chuangming Advanced Energy Materials Research Institute Co ltd
Priority date: 2021-05-26
Filing date: 2021-05-26
Publication date: 2023-09-05
Anticipated expiration: 2041-05-26
Also published as: CN113387400A

Abstract

The invention discloses a continuous production method and a device for in-situ doping of a precursor of a high-nickel ternary positive electrode material of a lithium ion battery, wherein the continuous production method comprises the following steps: preparing a raw material solution, preparing a precursor of a metal element doped nickel-cobalt-manganese ternary positive electrode material and preparing the ternary doped positive electrode material; the metal element doping time is injected in the middle and later stages of the formation of the secondary particles of the nickel cobalt manganese positive electrode material precursor. According to the invention, by improving the production method and the device thereof, the doping element is added in the later stage of the secondary particle formation and the growth period, so that the doping element, particularly the aluminum element, is doped on the surface of the high-nickel positive electrode material precursor, the cycle performance of the obtained high-nickel positive electrode material is improved, and the large-scale continuous production can be performed; the obtained precursor elements are uniformly distributed, the obtained positive electrode material precursor has high tap density, good sphericity, and the sintered ternary positive electrode material has good cycling stability and high charge and discharge performance.

Description

Continuous production method and device for in-situ doping of high-nickel ternary positive electrode material precursor of lithium ion battery

Technical Field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a continuous production method and a device for in-situ doping of a precursor of a high-nickel ternary positive electrode material of a lithium ion battery.

Background

Along with popularization and application of new energy automobiles, the requirements of people on the endurance mileage of the new energy automobiles are higher. As the power source of the pure electric vehicle, the energy density of the lithium ion power battery is gradually increased, and the energy density of the ternary positive electrode material from lithium iron phosphate to nickel cobalt manganese is increased from 100KW/Kg to 150KW/Kg, but the requirement of people on the endurance mileage of the new energy vehicle can not be met. The nickel-cobalt-manganese ternary positive electrode material is considered as a lithium ion battery positive electrode material with relatively high cost performance, on one hand, the increase of nickel content can improve the energy density of the battery, and on the other hand, the price is lower than that of a high-voltage positive electrode material such as lithium cobaltate and the like, so that the lithium ion battery positive electrode material is beneficial to large-scale production and use.

Although the high-nickel ternary cathode material can have high energy density, the high-nickel ternary cathode material has the defect that the cycling stability of the high-nickel cathode material is poor, the crystal structure of the high-nickel cathode material is collapsed in the cycling process of an interface between the high-nickel cathode material and electrolyte, so that the cathode material is pulverized, the energy exertion of the cathode material is influenced, and the performance attenuation is accelerated, so that doping of other chemical elements is urgently needed to form a stable surface crystal structure.

The commonly employed doping chemistry includes metal ions Al ³⁺ ，Zr ³⁺ And the like, wherein aluminum ions are more difficult to dope.

At present, a ternary positive electrode material precursor generally adopts a chemical coprecipitation technology, metal salt, a complexing agent and a precipitant are subjected to precipitation nucleation to form sheet-shaped primary particles, and along with continuous injection of the metal salt, the metal salt continuously grows up to form spherical secondary particles. The whole process can be divided into a nucleation period and a growing period. In the prior art, different transition metal salts are mixed according to a molar ratio to prepare a solution, and then the solution is subjected to precipitation reaction with a complexing agent and a precipitant to form a coprecipitation precursor, and then the coprecipitation precursor is sintered at a high temperature to obtain the anode material.

However, the doping process, especially the doping process of aluminum ions, is relatively difficult, and the main reason is that in the preparation process of the high-nickel precursor, the aluminum element is generally added in the nucleation period, and the reaction solution is in a high-pH value state, so that the aluminum element has acid-base amphoteric property, and is easy to form colloid in the high-pH value state, so that the growth of secondary particles is hindered, the particle growth of the precursor of the high-nickel positive electrode material is difficult, the tap density of the obtained positive electrode material is low, the sphericity is poor, and the yield of the final product is low. To solve this problem. In the prior art, a method of cleaning a high nickel precursor to reduce the pH of the solution and then doping and coating the solution is generally adopted. This method requires lowering the pH, which is time consuming and labor intensive. In addition, some processes dope aluminum into ternary materials by a subsequent heat treatment method, but the heat treatment method has a problem of uneven distribution of chemical elements.

In view of this, the present invention has been made.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a continuous production method and a device for in-situ doping of a high-nickel ternary positive electrode material precursor of a lithium ion battery, and by improving the production method and the device for in-situ doping of the high-nickel ternary positive electrode material precursor, not only is effective doping of doping elements, particularly aluminum elements, on the surface of the high-nickel positive electrode material precursor realized, but also the cycle performance of the prepared high-nickel positive electrode material is improved, and the large-scale continuous production of in-situ doping of the high-nickel ternary positive electrode material precursor can be realized.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

a continuous production method for in-situ doping of a precursor of a high-nickel ternary cathode material of a lithium ion battery, comprising the following steps: preparing a raw material solution, preparing a metal element doped nickel-cobalt-manganese positive electrode material precursor and preparing a ternary doped positive electrode material; the metal element doping time is injected in the middle and later stages of the formation of the secondary particles of the nickel cobalt manganese positive electrode material precursor.

In the invention, taking the doping of aluminum as an example, the doping time of the aluminum is injected in the middle and later stages of the formation of the secondary particles of the nickel cobalt manganese positive electrode material precursor, namely, the aluminum is added in the process of growing crystal nuclei of the nickel cobalt manganese positive electrode material precursor.

According to the preparation method, the adding time of the doping element soluble salt is controlled, and the precipitation process of the doping element and the coprecipitation of the ternary positive electrode material nickel, cobalt and manganese are effectively combined together to prepare the ternary doping precursor.

In the above continuous production method, as a preferable mode, in the preparation step of the raw material solution, the raw material solution includes a raw material solution I, a raw material solution II, a raw material solution III, and a raw material solution IV. Wherein, the raw material solution I is mixed metal salt solution, the raw material solution II is sodium hydroxide solution, the raw material solution III is ammonia water solution, and the raw material solution IV is mixed salt solution of doping elements (i.e. the raw material solution I containing the doping elements).

In the above continuous production method, in the preparation step of the raw material solution, the mixed metal salt solution is prepared by adding soluble salts of nickel, cobalt and manganese in proportion to prepare a solution.

In the above continuous production method, as a preferable mode, the metal element is added in the form of a soluble salt solution, wherein the soluble salt solution containing the metal element is prepared by: dissolving soluble salt containing metal elements into the same solution as the mixed metal salt solution used for preparing the nickel-cobalt-manganese positive electrode material precursor, and doping the metal elements on the surface of the positive electrode material precursor in the manner; rather than simply injecting a solution of the doping element into the reaction vessel. For example, in the invention, a nickel cobalt manganese mixed metal salt solution with the same mole ratio as nickel cobalt manganese in the high nickel cathode material is adopted, aluminum element is mixed with the mixed metal salt solution according to the designed mole ratio, and the aluminum element is doped on the surface of the precursor of the cathode material in such a way.

According to the invention, the metal element is added in an ionic state to participate in the precipitation reaction, so that the uniformity of metal element doping is ensured.

In the above continuous production method, as a preferable mode, the doping of the metal element may be performed in situ doping of one metal element, or may be performed in situ doping of two or more metal elements; preferably, the content of the doped metal element in the nickel-cobalt-manganese positive electrode material precursor is 1000-3000 ppm; preferably, the doping of the metal element may achieve in-situ doping of the aluminum element.

In the above continuous production method, as a preferred mode, the preparation process of the metal element doped nickel-cobalt-manganese ternary cathode material precursor sequentially comprises the steps of primary reaction, secondary reaction, continuous reaction, cleaning and drying, and finally the ternary doped precursor product is obtained.

In the continuous production method, as a preferable mode, the primary reaction is carried out under the condition of stirring, the raw material solution I, the raw material solution II and the raw material solution III are simultaneously added into a primary reaction kettle containing a base solution, the coprecipitation reaction of nickel, cobalt and manganese elements is continuously carried out in a reaction system along with the addition of the raw material solution, and the pH value of the reaction system is kept to be 11-12 by controlling the addition amount of the raw material solutions II and III, so as to obtain ternary nickel cobalt manganese precursor homogenate, namely ternary nickel cobalt manganese precursor suspension. In the primary reaction, overflow occurs when the homogenized ternary nickel-cobalt-manganese precursor reaches the overflow port of the primary reaction kettle, and the precursor is injected into the secondary reaction kettle.

According to the invention, with continuous addition of raw materials, when the pH of the mixed solution meets the requirement, adding of the raw material solutions II and III is suspended, three solutions added firstly are subjected to coprecipitation reaction, and then the added solutions are subjected to coprecipitation reaction continuously on the basis of the solutions; if the pH of the solution does not meet the requirements, the addition of the starting solutions II and III is continued so that the coprecipitation reaction can be continued and continued.

In the invention, primary crystal grains (i.e., crystal nuclei formed in the nucleation period) of the ternary nickel cobalt manganese precursor are formed in the primary reaction, and the crystal nuclei are flaky precipitates. With the continuous addition of the mixed metal salt solution, new flaky precipitate is continuously formed in the primary reaction, and under the stirring action, flaky primary grains are accumulated together with time to form spherical secondary grains, and the stage is called a grain growth process.

In the conventional process, doping of aluminum element is interposed in a nucleation stage, and because coprecipitation of the high nickel anode material is required to be performed in an environment with a higher pH value (pH value is 11-12), aluminum element easily forms aluminum hydroxide colloid in the environment with the pH value, and the colloid particles are mutually repelled due to the same charges, so that nucleation and secondary particle growth of a ternary precursor are hindered, and finally, precursor forming is difficult, and the sphericity of the secondary particles is poor.

In the above continuous production method, as a preferable mode, in the secondary reaction, when the liquid level of the secondary reaction kettle reaches a position where the stirring paddle can stir, in the stirring state, starting to inject the raw material solution IV to perform in-situ doping coprecipitation reaction; preferably, the pH of the secondary reaction system is 8 to 9.

In the above continuous production method, as a preferable mode, in the continuous reaction, after the product suspension of the secondary reaction reaches the overflow port of the secondary reaction kettle, overflow is injected into the aging kettle to perform continuous reaction, and the nickel-cobalt-manganese anode material precursor solution doped with the metal element is obtained.

In the invention, the doping of aluminum element is carried out in a secondary reaction, and at this time, after the nucleation of the high-nickel ternary positive electrode material precursor is completed, the crystal nucleus of the positive electrode material precursor in the secondary reaction is in a growing stage, namely, a stage of forming spherical secondary grains from primary grains. The newly added mixed metal continuously generates metal salt precipitate on the basis of the formed primary crystal grains, and the addition of the soluble aluminum salt solution does not influence the formation of crystal nucleus of the high-nickel ternary cathode material precursor, but is coated in the mixed metal salt precipitate in the form of aluminum hydroxide precipitate along with the formation of the mixed metal salt precipitate, so that the aluminum-doped high-nickel ternary cathode material precursor is formed.

In addition, in the secondary reaction, a large amount of alkali is consumed in the growth process of the crystal nucleus (from primary crystal grain growth to secondary crystal grain growth), so that the pH value of a reaction system is reduced, aluminum salt is added under the condition (pH is 8-9), aluminum element participates in the growth process of the ternary precursor secondary particles in an ionic state, aluminum hydroxide colloid of the aluminum element in an overbased solution (pH is 11-12) is avoided, and doping of the aluminum element is realized. Because the aluminum element is coated on the crystal nucleus along with the ternary positive electrode precursor material, the aluminum element is uniformly distributed in the ternary positive electrode material precursor.

In the above continuous production method, as a preferable mode, the volume of the secondary reaction kettle is 1.5 to 2.5 times that of the primary reaction kettle; preferably, the volume of the secondary reaction vessel is 2 times the volume of the primary reaction vessel.

In the invention, the reaction product grows into secondary grains from crystal nucleus in the primary reaction kettle, and when the ternary nickel cobalt manganese precursor homogenate reaches an overflow port, the grains grow long enough in the primary reaction kettle to reach a certain grain size, and the secondary grains can enter the secondary reaction kettle for subsequent reaction. Here, the volume of the reaction vessel determines the time of overflow in the primary reaction, which is also taken into consideration when designing the reaction vessel. By designing a proper reaction kettle, the ternary nickel cobalt manganese precursor homogenate enters the secondary reaction kettle through overflow at the initial stage of secondary particle formation.

In the above continuous production method, as a preferable mode, in the primary reaction, the base liquid is deionized water or a supernatant of a previous reaction product. The supernatant liquid here means a clear liquid obtained by precipitating the reaction product, wherein the solid and the liquid are separated from each other.

In the invention, when the coprecipitation reaction of nickel, cobalt and manganese elements is carried out for the first time, the base solution in the primary reaction kettle is deionized water.

In the above continuous production method, as a preferable mode, in the primary reaction, the base solution in the primary reaction vessel is heated to 50 to 55 ℃, and the raw material solution I, the raw material solution II and the raw material solution III are injected simultaneously by a peristaltic pump to carry out the coprecipitation reaction at 50 to 55 ℃. Preferably, the stirring speed is 200 to 400rpm; still more preferably, the peristaltic pump has an infusion rate of 50 to 200ml/min.

In the above continuous production method, as a preferable mode, in the secondary reaction, the raw material solution IV is injected into the secondary reaction tank by a peristaltic pump; the peristaltic pump injection speed is 1/5-1/3 of the peristaltic pump injection speed in the primary reaction process.

In the above continuous production method, as a preferable mode, the secondary reaction is carried out under stirring conditions at a stirring speed of 200 to 400rpm.

In the above continuous production method, as a preferable mode, in the secondary reaction, the doping reaction of the plurality of metal elements is performed simultaneously by preparing the raw material solution IV containing the plurality of metal elements according to the increased number of kinds of the metal elements, or the doping reaction of each element is performed separately by increasing the number of secondary reaction steps. For example, when the doped metal elements are two metal elements, adding a secondary reaction process II to perform in-situ doping reaction of the other element after the secondary reaction process I; when the doped metal elements are three metal elements, 2 secondary reaction processes (II and III) are added after the secondary reaction process I, and in-situ doping reaction of the other two metal elements is carried out.

In the above continuous production method, as a preferred mode, in the step of preparing the metal element doped nickel cobalt manganese positive electrode material precursor by coprecipitation, after the product suspension of the secondary reaction reaches the overflow port of the secondary reaction kettle, overflow is injected into the aging kettle to perform continuous reaction (i.e. aging), so as to obtain the metal element doped nickel cobalt manganese positive electrode material precursor solution.

In the above continuous production method, as a preferable mode, the aging reaction time in the continuous reaction is 7 to 9 hours, preferably 8 hours.

In the above continuous production method, as a preferred mode, in the cleaning step, the precursor solution of the nickel-cobalt-manganese positive electrode material doped with the metal element in the aging kettle is subjected to classified cleaning by a centrifuge, and dehydrated and dried to obtain a ternary doped precursor crude product. Preferably, the metal element doped nickel cobalt manganese positive electrode material precursor solution is subjected to low-speed, medium-speed and high-speed cleaning in a centrifugal machine.

In the above continuous production method, as a preferred mode, in the drying step, the ternary doped precursor crude product is dried in vacuum to obtain the ternary doped precursor product. The vacuum drying temperature is 110 ℃, and the drying time is 5-8 hours. Preferably, the drying time is 6 hours.

In the above continuous production method, as a preferable mode, in the preparation process of the ternary doped cathode material, the ternary doped precursor product is mixed with lithium hydroxide, and then sintered and crushed to obtain the ternary doped cathode material.

In the above continuous production method, as a preferable mode, in the preparation process of the ternary doped cathode material, the ternary doped precursor product and lithium hydroxide are mixed according to a molar ratio of 1:1.05.

In the above continuous production method, as a preferred mode, in the preparation process of the ternary doped cathode material, the ternary doped precursor product and lithium hydroxide after being uniformly mixed are transferred into a sintering furnace, and sintered at 580-600 ℃ under the condition of introducing oxygen. Preferably, the sintering time is 20 to 28 hours.

In the above continuous production method, as a preferable mode, in the preparation process of the ternary doped cathode material, the sintered product is crushed and screened to obtain the ternary doped cathode material.

In the continuous production method, as a preferable mode, the granularity of the ternary doped cathode material is 5-10 mu m; the tap density is 1.5-1.8 g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The charge-discharge performance of the ternary doped anode material is 160-180 mAh/g.

In the above-described continuous production method, as a preferable mode, the continuous production method may be carried out with doping of one element, or doping of two or more elements may be carried out. Preferably, the continuous production method is suitable for in-situ doping of aluminum element in a high-nickel ternary positive electrode material precursor of a lithium ion battery.

In the invention, doping of elements is carried out in the middle and later stages of secondary particle formation, the doping element is injected in a mode of injecting the doping element solution into a reaction kettle, salt solution with the same molar ratio as that of a high-nickel positive electrode material is adopted, doping is carried out in the secondary particle formation process (namely, in a reaction system in a secondary reaction kettle) after a positive electrode material precursor is nucleated, and compared with the mode of adding the doping element solution in the positive electrode material precursor nucleus stage (namely, in the reaction system in a primary reaction kettle), the prepared positive electrode material precursor nucleus is uniform, the sphericity of the secondary particles is good, and the tap density of the prepared precursor material is high.

The invention also provides a continuous production device for in-situ doping of the high-nickel ternary cathode material precursor of the lithium ion battery, which can realize large-scale continuous production of doping of aluminum element on the surface of the high-nickel cathode material precursor.

A continuous production device for in-situ doping of a precursor of a high-nickel ternary cathode material of a lithium ion battery comprises the following components: the device comprises a raw material solution storage device, a primary reaction device, a secondary reaction device, an ageing device and a centrifugal device. The raw material solution storage device is used for storing the prepared raw material solution; the primary reaction device is connected with the outlet of the raw material solution storage device and is used for preparing ternary nickel-cobalt-manganese precursor homogenate, namely, coprecipitation reaction of nickel, cobalt and manganese elements; the secondary reaction device is connected with the overflow outlet of the primary reaction device and is used for carrying out in-situ doping reaction of doping elements; the aging device is connected with the overflow port of the secondary reaction device and is used for aging the reaction liquid after doping elements to prepare a ternary doping precursor solution; the centrifugal device is connected with the feed liquid outlet of the aging device.

In the above-described continuous production apparatus, as a preferable mode, the continuous production apparatus may be configured to perform doping of one element, or may be configured to perform doping of two or more elements.

In the above continuous production apparatus, preferably, the volume of the secondary reaction apparatus is 1.5 to 2.5 times the volume of the primary reaction apparatus; preferably, the volume of the secondary reaction device is 2 times the volume of the primary reaction device.

In the above continuous production apparatus, as a preferable mode, the secondary reaction tank apparatus may include 1 or more secondary reaction apparatuses for doping 1 metal element or a plurality of metal elements. For example, the secondary reaction kettle device may comprise 1 secondary reaction kettle for doping 1 metal element or multiple metal elements, in which case, multiple metal elements may be mixed together to prepare a raw material solution IV containing multiple doping elements, and then the raw material solution IV is added in the doping reaction to perform the simultaneous doping reaction of multiple metal elements.

In the above continuous production apparatus, as a preferable mode, an inlet and an overflow are provided at an upper portion of a tank wall of the secondary reaction apparatus. The secondary reaction device is connected with the primary reaction device through a liquid injection pipe I, the liquid injection pipe I is a right-angle bent pipe, an inlet of the liquid injection pipe I is communicated with an overflow port arranged on the upper portion of the kettle wall of the primary reaction device, and the liquid injection pipe I is inserted into the secondary reaction device through an inlet on the upper portion of the kettle wall of the secondary reaction device and enables an outlet of the liquid injection pipe I to be close to the bottom of the secondary reaction device. The liquid injection pipe I is used for conveying liquid reaching the overflow port in the primary reaction device to the secondary reaction device.

In the above continuous production device, as a preferred mode, an inlet is formed in the upper portion of the tank wall of the aging device, the aging device is connected with the secondary reaction device through a liquid injection pipe II, the liquid injection pipe II is a right-angle elbow, the inlet of the liquid injection pipe II is communicated with an overflow port formed in the upper portion of the tank wall of the secondary reaction device, and the liquid injection pipe II is inserted into the aging device through the inlet of the upper portion of the tank wall of the aging device and enables the outlet of the liquid injection pipe II to be close to the bottom of the aging device. The liquid injection pipe II is used for conveying the liquid reaching the overflow port in the secondary reaction device to the aging device.

In the above continuous production apparatus, as a preferable mode, the primary reaction apparatus, the secondary reaction apparatus, and the aging apparatus are each provided with a stirring apparatus for stirring the reaction solution in the reaction apparatus.

In the above continuous production device, as a preferred mode, an inlet of the centrifugal device is connected with an outlet of the aging device, and is used for carrying out classified cleaning on the metal element doped nickel cobalt manganese positive electrode material precursor solution (ternary doped precursor solution) obtained in the aging reaction to remove impurities in the ternary doped precursor product; preferably, the solution in the aging device is fed to the centrifugal device by a pump.

In the above continuous production apparatus, as a preferable mode, the raw material solution storage means includes a raw material solution storage tank I, a raw material solution storage tank II, a raw material solution storage tank III, and a raw material solution storage tank IV. The raw material solution storage tank I is used for storing a mixed metal salt solution (namely a nickel cobalt manganese mixed metal salt solution); the raw material solution storage tank II is used for storing a precipitant, preferably sodium hydroxide solution; the raw material solution storage tank III is used for storing complexing agent, preferably ammonia water solution, and the raw material solution storage tank IV is used for storing mixed metal salt solution doped with metal elements.

In the above continuous production apparatus, as a preferable mode, the outlet of the raw material solution storage tank I is connected to the inlet I of the primary reaction apparatus through a pipeline, the outlet of the raw material solution storage tank II is connected to the inlet II of the primary reaction apparatus through a pipeline, and the outlet of the raw material solution storage tank III is connected to the inlet III of the primary reaction apparatus through a pipeline. And a peristaltic pump is arranged on a pipeline between the raw material solution storage device and the inlet of the primary reaction device and is used for pumping the raw material solution to the primary reaction device from the raw material solution storage device through the pipeline.

In the above continuous production apparatus, as a preferable mode, a peristaltic pump is provided on a line between the raw material solution storage tank IV and an inlet of the secondary reaction apparatus, and the peristaltic pump is used for pumping the solution stored in the raw material solution storage tank IV to the secondary reaction apparatus.

The raw material solution storage device can be a raw material solution storage tank, the primary reaction device can be a primary reaction kettle, the secondary reaction device can be a secondary reaction kettle, the aging device can be an aging kettle, and the centrifugal device can be a centrifugal machine. These devices are conventional devices for the preparation of nickel cobalt manganese ternary cathode material precursors.

The invention also provides a method for adjusting the pH value of the solution of the continuous production method for in-situ doping of the precursor of the high-nickel ternary cathode material of the lithium ion battery.

A method for adjusting the pH value of solution in the continuous production method of in-situ doping of high-nickel ternary positive electrode material precursor of lithium ion battery, wherein the method for adjusting the pH value consumes hydroxyl ions (OH) in the chemical reaction of metal doping elements ^- ) Formation ofAnd (3) precipitating, thereby reducing the pH value of the reaction solution and realizing the adjustment of the pH value of the solution.

In the above method for adjusting the pH of a solution, the pH is preferably 8 to 9.

In the above method for adjusting the pH of the solution, as a preferable mode, the method for adjusting the pH of the solution uses mixed metal salts of nickel, cobalt and manganese to consume hydroxyl ions (OH) in the coprecipitation reaction of metal elements ^- ) Forming a coprecipitation product of the metal element to lower the pH value of the solution.

In the invention, OH is consumed by coprecipitation of mixed metal elements ^- The pH of the subsequent reaction solution can generally reach 8-9.

In the invention, the pH value of the solution in the continuous production method can be directly adjusted by adopting a raw material solution without adding other reagents.

Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:

(1) According to the invention, by improving the production method and the device thereof, the doping element is added at the later stage of the secondary particle formation and the growth period, so that the doping element, particularly the aluminum element, is doped on the surface of the high-nickel positive electrode material precursor, the cycle performance of the obtained high-nickel positive electrode material is improved, and the large-scale continuous production can be performed.

(2) The precursor elements obtained by adopting the technical scheme of the invention are uniformly distributed, the formation of aluminum hydroxide colloid caused by higher pH value is avoided in the preparation process, the obtained positive electrode material precursor has high tap density, good sphericity, and the sintered ternary positive electrode material has good cycling stability and high charge and discharge performance.

(3) The technical scheme of the invention reduces the cleaning links and effectively improves the production efficiency.

Drawings

Fig. 1 is a flow chart of a process for preparing a ternary cathode material doped aluminum precursor in embodiment 1 of the invention.

Fig. 2 is an SEM image (10 μm) of a high nickel core-shell structure of 622 ternary cathode material formed in example 1 of the present invention, the core being 622 ternary material, the shell being 622 ternary cathode material doped with aluminum.

Fig. 3 is an SEM image (5 μm) of a 622 high nickel core-shell structure formed in example 1 of the present invention, the core being 622 ternary material, the shell being 622 ternary positive electrode material doped with aluminum.

Fig. 4 is a morphology diagram of the aluminum 622 doped ternary cathode material in example 1 of the present invention.

Fig. 5 is a graph showing the specific discharge capacity versus cycle number of 622 ternary cathode materials obtained in example 1 of the present invention before and after doping with aluminum.

Fig. 6 is a discharge specific capacity-cycle number curve of 811 ternary positive electrode materials doped with aluminum element obtained in example 4 and comparative example 1 of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made in detail and with reference to the accompanying drawings, wherein it is apparent that the embodiments described are only some, but not all embodiments of the present invention. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the invention, fall within the scope of protection of the invention.

The precursor of the lithium ion battery high-nickel ternary positive electrode material is a nickel-cobalt-manganese ternary positive electrode material doped with metal elements, the molar ratio of nickel to cobalt to manganese in the precursor can be the proportion of a conventional positive electrode material, and the doping amount of metal can also be the conventional doping amount, but in the preferred embodiment of the invention, the molar ratio of nickel to cobalt to manganese in the precursor is 6:2:2 or 8:1:1, and the content of the doped metal elements in the precursor is 1000-3000 ppm.

Example 1

As shown in fig. 1, which is a process flow chart for preparing a ternary positive electrode material doped aluminum precursor, the embodiment provides a continuous production method for preparing a high-nickel ternary positive electrode material precursor in-situ doped aluminum for a lithium ion battery, which comprises the following steps: preparing a raw material solution, preparing a metal element doped nickel-cobalt-manganese positive electrode material precursor and preparing a ternary doped positive electrode material. The metal element doping time is added in the process of growing crystal nuclei of the nickel cobalt manganese positive electrode material precursor; the metal element is added in the form of a soluble salt solution containing the metal element. The high-nickel ternary positive electrode material is 622 ternary material. The specific process is as follows:

Preparing a raw material solution:

(1) Raw material solution I: preparing a solution of raw materials of nickel sulfate, cobalt sulfate and manganese sulfate of the high-nickel ternary material according to a molar ratio of 6:2:2, and preparing 200L of 1mol/L mixed metal salt solution;

(2) Raw material solution II: preparing 200L of 3mol/L sodium hydroxide solution;

(3) Raw material solution III: preparing 200L of 2mol/L ammonia water solution;

(4) Raw material solution IV: firstly, preparing a mixed metal salt solution according to the molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate of 6:2:2, adding solid aluminum sulfate into the metal mixed salt solution according to the designed molar ratio of aluminum element and metal mixed salt, and mixing to prepare a 100L doped aluminum mixed salt solution with the aluminum content of 1000 ppm.

Preparing a metal element doped nickel-cobalt-manganese positive electrode material precursor:

(1) Primary reaction: the whole primary reaction is carried out under the stirring state, the bottom liquid (the bottom liquid can be deionized water or the supernatant of the last reaction product) in the primary reaction kettle I is heated to 50-55 ℃, and the stirring speed is kept at 200-400 rpm; the raw material solutions I, II and III are simultaneously injected into a 50L primary reaction kettle through a peristaltic pump, and coprecipitation reaction is carried out under the condition that the pH value is 11-12. Here, the raw material solutions are continuously added, and the addition amounts of the solution II and the solution III are controlled by the pH value.

When the reaction proceeds until the product in the primary reaction kettle reaches the overflow port, the reaction solution overflows and is injected into a secondary reaction kettle II of 100L.

(2) Secondary reaction: when the reaction solution injected into the secondary reaction kettle II reaches the position where the stirring paddle can stir, starting to inject the raw material solution IV, wherein the pH value of the solution is 8-9, the stirring speed is kept at 200-400 rpm, and the peristaltic pump injection speed is 1/5 of the peristaltic pump injection speed in the primary reaction. And after the raw material solution IV is injected into the secondary reaction kettle II, the doping reaction of elemental aluminum is started.

(3) Continuous reaction: when the reaction solution in the secondary reaction kettle II reaches the position of the overflow port of the reaction kettle II, the reaction solution overflows into a 200L ageing kettle, and the reaction solution is aged for 8 hours, so that the ternary doped aluminum precursor solution is obtained. Here, the aging time is from the end of the reaction, all the reaction products are pumped into the aging vessel and the time is started.

(4) Centrifuging and drying: and (3) centrifugally cleaning the ternary aluminum-doped precursor solution by using a centrifugal machine, and performing dehydration drying after cleaning the ternary aluminum-doped precursor solution at a low speed, a medium speed and a high speed in the centrifugal machine, and performing vacuum drying for 6 hours at 110 ℃ by using a double-cone dryer.

Preparing a ternary doped positive electrode material:

mixing the dried ternary aluminum-doped precursor and lithium hydroxide according to the molar ratio of 1:1.05, transferring into a sintering furnace after uniformly mixing, sintering for 24 hours at the temperature of 580-600 ℃ in an oxygen atmosphere, and cooling along with the furnace to obtain the ternary aluminum-doped 622 anode material.

The sintered positive electrode material is simply crushed and screened to obtain the aluminum-doped high nickel positive electrode material, and the granularity of the aluminum-doped high nickel positive electrode material is 5-10 mu m.

Fig. 2-3 are SEM images of the high nickel core-shell structure of 622 ternary materials formed in this example, wherein fig. 2 is a 10 μm SEM, and fig. 3 is an enlarged SEM image of fig. 2, 5 μm. As can be seen from fig. 2-3, by adopting the technical scheme of the embodiment, the prepared 622 ternary aluminum-doped cathode material has a high-nickel core-shell structure, wherein the core of the high-nickel core-shell structure is 622 ternary material, and the shell layer is 622 ternary material doped with aluminum.

Fig. 4 is a morphology diagram of the aluminum 622 doped ternary cathode material in example 1 of the present invention. As can be seen from FIG. 4, the tap density of the positive electrode material precursor (1.5-1.8 g/cm ³ ) High sphericity and firm combination of elements in the material.

Preparation of the cell and electrochemical performance test:

the ternary positive electrode material obtained in the embodiment, the conductive agent acetylene black and the binder PVDF are mixed according to the mass ratio of 8:1:1 Grinding for half an hour, dripping NMP (azamethylpyrrolidone) to be pasty, uniformly coating on an aluminum foil, drying, and rolling to form a punched piece to obtain a positive plate; the lithium metal sheet is used as a negative electrode, the polypropylene microporous membrane is used as a diaphragm, and 1mol/L LiPF is used ₆ As an electrolyte, a button CR2032 type battery was assembled in a glove box.

And respectively carrying out charge and discharge cycle test on the assembled battery at room temperature. Fig. 5 is a graph showing the specific discharge capacity versus cycle number of 622 ternary materials obtained in example 1 of the present invention before and after doping with aluminum.

As can be seen from fig. 5, compared with the 622 ternary material before the aluminum is undoped, the 622 ternary material doped with aluminum has a significantly increased discharge specific capacity after the aluminum is doped in the charge-discharge cycle; and with the increase of the charge-discharge cycle times, the 622 ternary material doped with aluminum has stable charge-discharge cycle and smaller discharge specific capacity attenuation.

Example 2

The embodiment provides a continuous production method for in-situ doping aluminum and zirconium into a precursor of a high-nickel ternary positive electrode material of a lithium ion battery, wherein the high-nickel ternary positive electrode material is 622 ternary material. In comparison with example 1, the production method and its process parameters were the same except for the preparation method of the raw material solution IV and the sintering step in the preparation of the ternary doped cathode material. Specifically:

Preparing a raw material solution IV: after 200L of the raw material solution I was prepared, 342.15g (1 mol) of solid aluminum sulfate and 566.7g (2 mol) of solid zirconium sulfate were added to the raw material solution I and mixed uniformly.

Preparing a ternary doped positive electrode material:

mixing the dried ternary aluminum-zirconium-doped precursor and lithium hydroxide according to the molar ratio of 1:1.05, transferring into a sintering furnace after uniform mixing, dehydrating for 6 hours at 380 ℃ in an oxygen atmosphere, heating to 580-600 ℃ for sintering, preserving heat for 24 hours, and cooling along with the furnace to obtain the aluminum-zirconium 622 ternary anode material.

The sintered positive electrode material is simply crushed and screened to obtain the aluminum-zirconium-doped high-nickel positive electrode material.

Example 3

The embodiment provides a continuous production method for in-situ doping aluminum and zirconium into a precursor of a high-nickel ternary positive electrode material of a lithium ion battery, wherein the high-nickel ternary positive electrode material is 811 ternary material. The continuous production method comprises the following steps: preparing a raw material solution, doping metal elements and preparing a ternary doped anode material. The method comprises the following steps:

preparing a raw material solution:

(1) Raw material solution I: preparing industrial grade raw materials of nickel sulfate, cobalt sulfate and manganese sulfate into a solution according to the molar ratio of Ni to Co to Mn=8:1:1 to prepare 200L1mol/L mixed metal salt solution;

(3) Raw material solution III: preparing 200L of 2mol/L ammonia water solution;

(4) Raw material solution IV: firstly, preparing 200L of 1mol/L mixed metal salt solution according to the mole ratio of Ni to Co to Mn=8 to 1, adding 342.15g (1 mol) of solid aluminum sulfate and 566.7g (2 mol) of solid zirconium sulfate into a raw material solution IV, and uniformly mixing.

Doping of metal elements:

(1) Primary reaction: heating the base solution (the base solution can be deionized water or supernatant of the last reaction product) in the primary reaction kettle I to 50-55 ℃, and opening a stirring paddle to keep the stirring speed of 200-400 rpm; the raw material solutions I, II and III are simultaneously injected into a 100L reaction kettle through a peristaltic pump, and coprecipitation reaction is carried out under the condition that the pH value is 11-12. Here, the raw material solutions are continuously added, and the addition amounts of the solution II and the solution III are controlled by the pH value.

When the reaction is carried out until the product in the primary reaction kettle reaches the overflow port, the reaction solution overflows and is injected into a 200L secondary reaction kettle II.

(2) Secondary reaction: when the reaction solution injected into the secondary reaction kettle II reaches the position where the stirring paddle can stir, starting to inject the raw material solution IV, wherein the pH value of the solution is 8-9, the stirring speed is kept at 200-400 rpm, and the peristaltic pump injection speed is 1/5 of the primary peristaltic pump injection speed. And after the raw material solution IV is injected into the secondary reaction kettle II, the doping reaction of the aluminum element and the zirconium element is started.

(3) Continuous reaction: when the reaction solution in the secondary reaction kettle II reaches the position of the overflow port of the reaction kettle II, the reaction solution overflows into an aging kettle, and the reaction solution is aged for 8 hours, so that 811 ternary doped aluminum zirconium precursor solution is obtained. Here, the aging time is from the end of the reaction, all the reaction products are pumped into the aging vessel and the time is started.

Preparing a ternary doped positive electrode material:

mixing the dried ternary aluminum-zirconium-doped precursor and lithium hydroxide according to the molar ratio of 1:1.05, transferring into a sintering furnace after uniform mixing, dehydrating for 6 hours at 380 ℃ in an oxygen atmosphere, heating to 580-600 ℃ for sintering, preserving heat for 24 hours, and cooling along with the furnace to obtain the ternary aluminum-zirconium 811-doped anode material.

And (3) simply crushing the sintered aluminum-zirconium 811-doped ternary cathode material, and screening to obtain the aluminum-zirconium-doped high-nickel 811 cathode material.

Example 4

This example prepares an aluminum 811 doped ternary cathode material according to the method in example 3. That is, in the raw material solution preparation, solid zirconium sulfate was not added to the raw material solution IV, as compared with example 3; other schemes were the same as in example 3. That is, the doping reaction of the aluminum element is performed in the secondary reaction, and at this time, the crystal nuclei of the nickel cobalt manganese positive electrode material precursor are in a growth stage from the flaky primary crystal grains to the spherical secondary crystal grains.

Batteries were prepared and subjected to electrochemical performance testing according to the preparation of the batteries and the electrochemical performance testing method thereof in example 1, and the discharge specific capacity-cycle number curve of the aluminum-doped 811 cathode material of this example is shown in fig. 6.

Comparative example 1

This comparative example, in which an aluminum-doped 811 cathode material was provided, the doping timing of the Al element was added at the nucleation stage of the precursor of the cathode material, that is, in the primary reaction, as compared with example 4, was prepared. Specifically, the reaction steps are as follows:

(1) Primary reaction: heating the base solution in the primary reaction kettle I to 50-55 ℃, and opening a stirring paddle to keep the stirring speed of 200-400 rpm; the raw material solutions I, II and III are simultaneously injected into a 100L reaction kettle through a peristaltic pump, and coprecipitation reaction is carried out under the condition that the pH value is 11-12. Then adding aluminum sulfate solution to carry out doping reaction of aluminum element. Here, the raw material solutions are continuously added, and the addition amounts of the solution II and the solution III are controlled by the pH value.

(2) Secondary reaction: when the reaction solution injected into the secondary reaction kettle II reaches the position where the stirring paddle can stir, starting to inject the raw material solution I, wherein the pH value of the solution is 8-9, the stirring speed is kept at 200-400 rpm, and the peristaltic pump injection speed is 1/5 of the primary peristaltic pump injection speed.

(3) Continuous reaction: when the reaction solution in the secondary reaction kettle II reaches the position of the overflow port of the reaction kettle II, the reaction solution overflows into an aging kettle, and the reaction solution is aged for 8 hours, so that 811 ternary doped aluminum precursor solution is obtained. Here, the aging time is from the end of the reaction, all the reaction products are pumped into the aging vessel and the time is started.

Batteries were prepared and subjected to electrochemical performance testing according to the preparation of the batteries and the electrochemical performance testing method thereof in example 1, and as shown in fig. 6, the discharge specific capacity-cycle number curve of the aluminum-doped 811 cathode material prepared by adding aluminum element to the precursor of the cathode material during the nucleation period of the precursor of the present comparative example.

As can be seen from fig. 6, compared with the comparative example 1, in which aluminum is doped at the nucleation stage of the nickel cobalt manganese positive electrode material precursor, in example 4, aluminum is doped during the growth of the crystal nucleus of the nickel cobalt manganese positive electrode material precursor, and the prepared ternary doped positive electrode material has higher specific discharge capacity at different cycle times, especially after the battery cycle times exceed 600 times.

The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A continuous production method for in-situ doping of a precursor of a high-nickel ternary positive electrode material of a lithium ion battery is characterized in that,

the continuous production method comprises the following steps: preparing a raw material solution, preparing a precursor of a metal element doped nickel-cobalt-manganese ternary positive electrode material and preparing the ternary doped positive electrode material; the metal element doping time is injected in the middle and later stages of the formation of the secondary particles of the nickel cobalt manganese anode material precursor;

the metal element is one metal element, and in-situ doping of two or more metal elements, wherein the metal element comprises aluminum;

In the preparation process of the raw material solution, the raw material solution comprises a raw material solution I, a raw material solution II, a raw material solution III and a raw material solution IV; wherein,,

the raw material solution I is mixed metal salt solution, the raw material solution II is sodium hydroxide solution, the raw material solution III is ammonia water solution, and the raw material solution IV is mixed salt solution doped with metal elements;

the preparation of the mixed metal salt solution is to prepare a solution by adding soluble salts of nickel, cobalt and manganese in proportion;

the doping metal element is added in a mode of soluble salt solution, wherein the soluble salt solution containing the doping metal element is prepared by the following mode: dissolving a soluble salt containing a doping metal element into the same solution as the mixed metal salt solution;

the preparation process of the metal element doped nickel-cobalt-manganese ternary positive electrode material precursor sequentially comprises primary reaction, secondary reaction, continuous reaction, cleaning and drying to obtain a ternary doped precursor product; wherein,,

the primary reaction is carried out under the stirring condition, a raw material solution I, a raw material solution II and a raw material solution III are simultaneously added into a primary reaction kettle containing a base solution, the coprecipitation reaction of nickel, cobalt and manganese elements is continuously carried out in a reaction system along with the addition of the raw material solution, and the pH value of the reaction system is kept to be 11-12 by controlling the addition amount of the raw material solution II and the raw material solution III, so that ternary nickel-cobalt-manganese precursor homogenate is obtained; in the primary reaction, overflow occurs when the homogenization of the ternary nickel cobalt manganese precursor reaches the position of an overflow port of the primary reaction kettle, and the primary reaction kettle is injected with the ternary nickel cobalt manganese precursor;

In the secondary reaction, when the liquid level of the secondary reaction kettle reaches the position where the stirring paddle can stir, starting to inject the raw material solution IV to perform in-situ doping coprecipitation reaction under the stirring state; the pH of the secondary reaction system is 8-9; the pH of the secondary reaction system is that OH is consumed in the process of growing crystal nucleus ^- Or co-precipitation of mixed metal elements consumes OH ^- To control;

in the continuous reaction, after the product suspension of the secondary reaction reaches an overflow port of the secondary reaction kettle, overflow is injected into an aging kettle for continuous reaction, and the nickel-cobalt-manganese anode material precursor solution doped with metal elements is obtained.

2. The continuous production method according to claim 1, wherein the content of the doped metal element in the nickel-cobalt-manganese positive electrode material precursor is 1000-3000 ppm.

3. The continuous production method according to claim 1, wherein,

the volume of the secondary reaction kettle is 1.5-2.5 times of that of the primary reaction kettle.

4. The continuous production method according to claim 1, wherein in the continuous reaction step, the aging reaction time is 7 to 9 hours.

5. The continuous production method according to claim 1, wherein in the cleaning step, the precursor solution of the nickel-cobalt-manganese positive electrode material doped with the metal element in the aging kettle is subjected to classified cleaning by a centrifuge, and is dehydrated and dried to obtain a ternary doped precursor crude product.

6. The continuous production method according to claim 5, wherein the metal element doped nickel cobalt manganese positive electrode material precursor solution is subjected to low, medium and high speed cleaning in a centrifuge.

7. The continuous production method according to claim 1, wherein,

in the primary reaction, the base solution in the primary reaction kettle is heated to 50-55 ℃, and raw material solution I, raw material solution II and raw material solution III are simultaneously injected through a peristaltic pump to carry out coprecipitation reaction at 50-55 ℃.

8. The continuous production process according to claim 7, wherein in the primary reaction, the base liquid is deionized water or a supernatant of a previous reaction product.

9. The continuous production method according to claim 7, wherein in the primary reaction, the stirring speed is 200 to 400rpm.

10. The continuous production method according to claim 7, wherein the peristaltic pump is injected at a rate of 50 to 200 ml/min in the primary reaction.

11. The continuous production method according to claim 1, wherein,

the secondary reaction is carried out under stirring conditions, and the stirring speed is 200-400 rpm.

12. The continuous production method according to claim 1, wherein in the secondary reaction, the raw material solution IV is injected into the secondary reaction tank by a peristaltic pump; the peristaltic pump injection speed is 1/5-1/3 of the peristaltic pump injection speed in the primary reaction process.

13. The continuous production method according to claim 1, wherein in the secondary reaction, the doping reaction of the plurality of metal elements is performed simultaneously by preparing the raw material solution IV containing the plurality of doping metal elements according to the increased number of species of the doping metal elements, or the doping reaction of each element is performed separately by increasing the number of secondary reaction steps.

14. The continuous production method according to claim 1, wherein,

in the preparation process of the ternary doped cathode material, a ternary doped precursor product is mixed with lithium hydroxide, sintered and crushed to obtain the ternary doped cathode material; and mixing the ternary doped precursor product with lithium hydroxide according to a molar ratio of 1:1.05.

15. The continuous production method according to claim 1, wherein in the preparation process of the ternary doped cathode material, the ternary doped precursor product and lithium hydroxide after being uniformly mixed are transferred into a sintering furnace, and sintered at 580-600 ℃ for 20-28 hours under the condition of introducing oxygen.

16. The continuous production method according to any one of claims 1 to 15, characterized in that,

the granularity of the ternary doped anode material is 5-10 mu m; the tap density is 1.5-1.8 g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the Ternary elementThe charge-discharge performance of the doped anode material is 160-180 mAh/g.