A high-nickel ternary positive electrode material containing latp and a preparation method thereof

Abstract

The application relates to a high-nickel ternary positive electrode material containing LATP and a preparation method thereof. A LATP aqueous nano-slurry with a particle size distribution of 70nm-100nm is used as one of raw materials for preparing the high-nickel ternary positive electrode material, uniform compounding of the nano-LATP and the high-nickel ternary material is realized in a sol-gel process, and then through drying and sintering, a powder material capable of being used as an active substance of a positive electrode slurry is obtained. Through uniform mixing of the LATP into the high-nickel ternary material, the electrochemical performance and thermal safety of the high-nickel ternary positive electrode material are improved, and after the high-nickel ternary positive electrode material is used in a battery positive electrode or further used in a lithium ion battery, the thermal safety of the battery can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to a high-nickel ternary positive electrode material containing LATP and a preparation method thereof. BACKGROUND

[0002] With the continuous development of today's technology, in the face of global energy crisis, traditional fossil energy is facing exhaustion and causing environmental pollution and greenhouse gas emission problems, many countries and regions have introduced policies to support the development of new energy vehicles and lithium ion batteries, continuous investment in scientific research has continuously improved the energy density of lithium ion batteries, prolonged the cycle life, and reduced the manufacturing cost of the large-scale automated production line and improved the reliability, and the improvement of the performance-price ratio has accelerated the wide application of lithium ion batteries in various fields, such as electric vehicles, energy storage systems, portable electronic devices and special fields.

[0003] Under the background of the continuous scale-up of lithium ion batteries, the market environment also puts forward higher technical requirements for lithium ion batteries, and the biggest contradiction is the balance between the improvement of the specific energy of lithium ion batteries and the guarantee of thermal safety performance. The market demands batteries with higher capacity and energy, smaller volume, lighter weight and more excellent charging and discharging performance, and the positive electrode material is from lithium iron phosphate system to lithium cobaltate system and ternary system, to 8-system and 9-system ternary system, the specific energy is improved while the safety performance is reduced, and the problem of thermal safety of lithium ion batteries is more and more concerned by people. Therefore, it is of great significance to develop high-nickel ternary positive electrode materials with higher specific energy and thermal safety performance. The existing invention usually coats a layer of LATP solid electrolyte on the surface of the high-nickel ternary positive electrode material, but this method generally has the problem of uneven coating, which limits the lithium ion conduction in the local area of the electrode sheet, and cannot fully improve the overall electrochemical performance and thermal safety. SUMMARY

[0004] To solve the above technical problems, the application provides a high-nickel ternary positive electrode material containing LATP and a preparation method thereof.

[0005] The technical scheme adopted by the application is: a preparation method of a high-nickel ternary positive electrode material containing LATP, comprising the following steps:

[0006] Step one: dissolving a nickel source, a cobalt source, a manganese source or an aluminum source and a lithium source in water together, adding a complexing agent and a LATP aqueous nano slurry, and mixing uniformly;

[0007] Step two: continuously stirring the above mixture under heating conditions until a gel is formed;

[0008] Step three: drying the gel, sintering at 80-200 DEG C, and grinding into powder;

[0009] Step four: sintering the powder at 300-600 DEG C to obtain the high-nickel ternary positive electrode material containing LATP.

[0010] Preferably, the molar ratio of lithium:nickel:cobalt:manganese or aluminum is 1.03:0.5:0.2:0.3-1.05:0.9:0.05:0.05.

[0011] Preferably, step one is also doped with a magnesium salt and / or a titanium salt.

[0012] Preferably, the metal salt is a mixture of one or more of a sulfate, a nitrate, and a chloride.

[0013] Preferably, the complexing agent is one or more of citric acid, EDTA, and ammonia, and the amount added is 1-2 times the total number of moles of metal ions.

[0014] Preferably, the particle size of the LATP aqueous slurry is 70-100 nm, and the mass of the LATP is 0.5%-2% of the mass of the high-nickel ternary positive electrode material.

[0015] Preferably, the heating temperature in step two is 60-100 DEG C.

[0016] The high-nickel ternary positive electrode material containing LATP is prepared by the method.

[0017] A battery positive electrode is prepared from a positive electrode slurry comprising the high-nickel ternary positive electrode material containing LATP.

[0018] A lithium ion battery comprises the battery positive electrode.

[0019] The present application has the advantages and positive effects that the prepared positive electrode material has a good lithium ion conduction path, and its intrinsic thermal safety is also significantly enhanced, and the lithium ion battery prepared therefrom can improve the thermal safety of the lithium ion battery; in addition, the positive electrode material prepared by the method has a simple and effective element doping manner and is uniformly mixed; the main metal elements Ni, Co, Mn, and Li are uniformly distributed, and the positive electrode material is simple to prepare and does not need to be additionally sintered with a Li source, thereby optimizing the preparation steps.

[0020] The components in the positive electrode material are mixed at the nanoscale, and compared with the conventional coating method, the LATP components are more uniformly distributed; the uniformly distributed LATP components provide a continuous and efficient lithium ion transmission channel, enhance the stability of the material in a high-temperature environment, and reduce the safety risks caused by temperature rise. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 SEM image of the high-nickel ternary positive electrode material containing LATP prepared in Example 1. DETAILED DESCRIPTION

[0022] Embodiments of the present application will be described below with reference to the accompanying drawings.

[0023] The present application relates to a high-nickel ternary positive electrode material containing LATP and a preparation method thereof. The LATP aqueous nano-slurry with a particle size distribution of 70-100 nm is used as one of raw materials for preparing the high-nickel ternary positive electrode material. In the sol-gel process, the nano-LATP is uniformly compounded with the high-nickel ternary material, thereby improving the electrochemical performance and thermal safety of the high-nickel ternary positive electrode material.

[0024] In the preparation, the nickel source, the cobalt source, the manganese source or the aluminum source are mixed, and a metal salt such as magnesium or titanium can be doped according to the need. The mixture is mixed with a complexing agent, and then the LATP (Li 1.3 Al 0.3 Ti 1.7 (PO4)3) aqueous nano-slurry is added. The gel state is formed by the sol-gel method. After the gel material is dried and sintered, the active ingredient for preparing the positive electrode slurry is obtained. The LATP is uniformly compounded in the ternary material through the uniform mixing of the solution level. Further, the active ingredient can be prepared into a lithium ion battery positive electrode, and then assembled into a lithium ion battery. It is found through the test that the prepared lithium ion battery has excellent thermal safety.

[0025] The high-nickel ternary positive electrode material containing the LATP is prepared according to the following method.

[0026] Step 1: The metal salts such as the nickel source, the cobalt source, the manganese source or the aluminum source are dissolved in deionized water together with the lithium source to form a uniform mixed solution. In some embodiments of the present application, the doping elements in the form of metal salts such as magnesium salt and titanium source can also be added. The complexing agent citric acid is added in an amount of 1-2 times the total number of moles of metal ions in the solution to prevent the precipitation of metal ions. The LATP aqueous nano-slurry is added to the solution, and the mass of the LATP accounts for 0.5%-2% of the mass of the high-nickel ternary positive electrode material. The mixed solution is fully stirred and mixed uniformly.

[0027] The metal salt is the nickel source, the cobalt source, the manganese source or the aluminum source, which can be one or several of sulfate, nitrate and chloride. The complexing agent is selected from one or several of citric acid, EDTA and ammonia. The particle size of the LATP aqueous slurry is 70-100 nm. The molar ratio of lithium:nickel: cobalt:manganese (aluminum) is 1.03:0.5:0.2:0.3-1.05:0.9:0.05:0.05.

[0028] Step 2: The above mixed solution is continuously stirred under the heating condition of 60-100°C to promote the good combination of the LATP and other components, so that the mixed solution gradually changes into a transparent sol state. The heating is continued until the sol changes into a gel, and then the heating is stopped.

[0029] Step 3: The formed gel is placed in an oven at 60-100°C for drying treatment to remove excess water. The dried gel is subjected to preliminary low-temperature pre-sintering at a temperature range of 80-200°C to remove volatile and low-temperature decomposable substances in the gel, avoid the formation of a large number of pore structures in the material, and make the material preliminarily densified. After sintering, the material is ground into powder and sieved.

[0030] Step 4: The powder is subjected to high-temperature sintering at 300-600°C to further improve the density of the material and optimize the crystal structure. After sieving, a high-nickel ternary positive electrode material containing LATP with excellent structural properties is obtained.

[0031] The above preparation process can prepare a high-nickel ternary positive electrode material in which LATP is uniformly distributed in the material. The material has a good lithium ion conduction path and its intrinsic thermal safety is significantly enhanced. The material can be used as an active ingredient in a positive electrode slurry. Lithium salt does not need to be added to the positive electrode slurry. The nickel ternary positive electrode material can be mixed with a conductive agent and a binder to prepare a positive electrode slurry, which can be further used to prepare a battery positive electrode. The components in the positive electrode material are mixed at the nanoscale, and the LATP component is more uniformly distributed than in the conventional coating method. The uniformly distributed LATP component provides a continuous and efficient lithium ion transport channel, enhances the stability of the material in a high-temperature environment, and reduces the safety risks caused by temperature rise.

[0032] The experimental methods of the operation steps are not specifically described in the following description of the embodiments of the present application, and are performed according to the corresponding product instructions. The instruments, reagents, and consumables used in the examples can be purchased from commercial companies unless otherwise specified. The sources of all raw materials in the present application are not particularly limited, and they can be prepared by conventional methods known to those skilled in the art. The purity of all raw materials in the present application is not particularly limited, and analytical pure or conventional purity in the lithium ion battery field can be used in the present application.

[0033] Example 1:

[0034] Nickel chloride, cobalt chloride, manganese chloride, and lithium chloride were dissolved in water, with lithium:nickel: cobalt:manganese added at a molar ratio of 1.05:0.8:0.1:0.1. Citric acid was added to the solution at 1.2 times the total number of metal ions, and then the mixture was stirred to dissolve. Then, 1% of a LATP aqueous nano-slurry (average particle size 70-100 nm) was added to the ternary material, and the mixture was stirred to mix uniformly. The mixture was heated at 80°C and continuously stirred to promote the good combination of LATP and other components, and the mixture gradually changed into a transparent sol state. Heating was continued at 80°C until the sol changed into a gel, and then heating was stopped.

[0035] The prepared gel is placed in an 80°C oven for drying treatment to remove excess water, the dried gel is ground into powder, and then pre-sintered at 150°C for 3h and sieved through a 200 mesh screen. The obtained powder is sintered at 550°C for 12h and sieved through a 200 mesh screen to obtain a high-nickel ternary positive electrode material with excellent structural properties, in which the LATP is uniformly distributed inside the material. The microstructure of the prepared high-nickel ternary positive electrode material containing LATP is observed, and the SEM image is as shown in FIG. 2. As shown in FIG. 2, the overall particles are uniformly distributed, have certain agglomeration phenomenon, irregular morphology, and rough surface, etc. Figure 1

[0036] Example 2:

[0037] Nickel chloride, cobalt chloride, aluminum chloride, and lithium chloride are dissolved in water, in which lithium:nickel: cobalt: aluminum is added in a molar ratio of 1.05:0.8:0.1:0.1; after adding 2 times the amount of citric acid based on the total number of metal ions in the solution, the solution is fully stirred and dissolved, and then 0.5% of the LATP aqueous nano slurry (average particle size 70nm-100nm) based on the mass of the ternary material is added, and the mixture is fully stirred and mixed uniformly. The mixture is continuously stirred under heating at 80°C to promote good combination of the LATP with other components, so that the mixture gradually changes into a transparent sol state; heating at 80°C is continued until the sol changes into a gel, and then heating is stopped.

[0038] The prepared gel is placed in an 80°C oven for drying treatment to remove excess water, the dried gel is ground into powder, and then pre-sintered at 200°C for 2h and sieved through a 200 mesh screen. The obtained powder is sintered at 550°C for 12h and sieved through a 200 mesh screen to obtain a high-nickel ternary positive electrode material containing LATP with excellent structural properties, in which the LATP is uniformly distributed inside the material.

[0039] Example 3:

[0040] Nickel chloride, cobalt chloride, aluminum chloride, lithium chloride, magnesium chloride, and titanium chloride are dissolved in water, in which lithium:nickel: cobalt: aluminum: magnesium: titanium is added in a molar ratio of 1.05:0.8:0.1:0.1:0.05:0.05; after adding 1.2 times the amount of citric acid based on the total number of metal ions in the solution, the solution is fully stirred and dissolved, and then 1% of the LATP aqueous nano slurry (average particle size 70nm-100nm) based on the mass of the ternary material is added, and the mixture is fully stirred and mixed uniformly.

[0041] The mixture is continuously stirred under heating at 80°C to promote good combination of the LATP with other components, so that the mixture gradually changes into a transparent sol state; heating at 80°C is continued until the sol changes into a gel, and then heating is stopped.

[0042] ​The prepared gel is placed in an oven at 80°C for drying treatment to remove excess water, the dried gel is ground into powder, and then pre-sintered at 200°C for 2h and sieved through a 200 mesh screen. The obtained powder is sintered at 550°C for 12h and sieved through a 200 mesh screen to obtain a high-nickel ternary positive electrode material containing LATP with excellent structural properties, in which the LATP is uniformly distributed inside the material.

[0043] Example 4:

[0044] The high-nickel ternary positive electrode material containing LATP prepared in Example 1 is mixed with the conductive agent CNT and the binder PVDF in NMP solution at a mass ratio of 97:1:2, and high-speed stirring is performed at a rotation speed of 2500 rpm for 3h to obtain a lithium battery positive electrode slurry.

[0045] The prepared positive electrode slurry is coated on an aluminum foil, and a positive electrode sheet is obtained after drying. The positive electrode sheet, a graphite negative electrode (graphite: conductive agent: binder = 96:2:2), and a separator are laminated, packaged, baked, injected, sealed, placed, formed, degassed, and sealed, and a 20Ah-level battery 1 is prepared. The battery 1 is tested, and the test results are shown in Table 1.

[0046] Example 5:

[0047] The high-nickel ternary positive electrode material containing LATP prepared in Example 1 is mixed with the conductive agent CNT and the binder PVDF in NMP solution at a mass ratio of 97:1:2, and high-speed stirring is performed at a rotation speed of 2500 rpm for 3h to obtain a lithium battery positive electrode slurry.

[0048] The positive electrode slurry is coated on an aluminum foil, and a positive electrode sheet is obtained after drying. The positive electrode sheet, a graphite negative electrode (graphite: conductive agent: binder = 96:2:2), and a separator are laminated, packaged, baked, injected, sealed, placed, formed, degassed, and sealed, and a 20Ah-level battery 1 is prepared. The battery 1 is tested, and the test results are shown in Table 1.

[0049] Example 6:

[0050] The high-nickel ternary positive electrode material containing LATP prepared in Example 1 is mixed with the conductive agent CNT and the binder PVDF in NMP solution at a mass ratio of 97:1:2, and high-speed stirring is performed at a rotation speed of 2500 rpm for 3h to obtain a lithium battery positive electrode slurry.

[0051] The positive electrode slurry is coated on an aluminum foil, and a positive electrode sheet is obtained after drying. The positive electrode sheet, a graphite negative electrode (graphite: conductive agent: binder = 96:2:2), and a separator are laminated, packaged, baked, injected, sealed, placed, formed, degassed, and sealed, and a 20Ah-level battery 1 is prepared. The battery 1 is tested, and the test results are shown in Table 1.

[0052] Example 7:

[0053] The high-nickel ternary positive electrode material containing LATP prepared in Example 2 was mixed with the conductive agent CNT and the binder PVDF in an NMP solution according to a mass ratio of 97:1:2, high-speed stirring was performed at a rotating speed of 2500 rpm for 3 h, and a positive electrode slurry was obtained.

[0054] The positive electrode slurry was coated on an aluminum foil, and a positive electrode sheet was obtained after drying. The positive electrode sheet, a graphite negative electrode (graphite:silicon:conductive agent:binder = 88:8:2:2), and a separator were laminated, packaged, baked, injected, packaged, and allowed to stand, and a 20 Ah battery 4 was prepared by formation and capacity grading. The battery was tested, and the test results are shown in Table 1.

[0055] Example 8:

[0056] The high-nickel ternary positive electrode material containing LATP prepared in Example 3 was mixed with the conductive agent CNT and the binder PVDF in an NMP solution according to a mass ratio of 97:1:2, high-speed stirring was performed at a rotating speed of 2500 rpm for 3 h, and a positive electrode slurry was obtained.

[0057] The positive electrode slurry was coated on an aluminum foil, and a positive electrode sheet was obtained after drying. The positive electrode sheet, a graphite negative electrode (graphite:silicon:conductive agent:binder = 88:8:2:2), and a separator were laminated, packaged, baked, injected, packaged, and allowed to stand, and a 20 Ah battery 5 was prepared by formation and capacity grading. The battery was tested, and the test results are shown in Table 1.

[0058] Comparative Example 1:

[0059] The LATP slurry, the conductive agent CNT, and the binder PVDF were first uniformly mixed in an NMP solution, and then the NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2) material was added, and the total mass was mixed according to a mass ratio of positive electrode material: LATP: conductive agent: binder = 96.5:0.5:1:2, and high-speed stirring was performed at a rotating speed of 2500 rpm for 3 h, and a positive electrode slurry was obtained.

[0060] The positive electrode slurry was coated on an aluminum foil, and a positive electrode sheet was obtained after drying. The positive electrode sheet, a graphite negative electrode (graphite:silicon:conductive agent:binder = 88:8:2:2), and a separator were laminated, packaged, baked, injected, packaged, and allowed to stand, and a 20 Ah battery 6 was prepared by formation and capacity grading. The battery was tested, and the test results are shown in Table 1.

[0061] Battery performance test

[0062] The batteries obtained in each example and comparative example were tested, and the test items and steps were as follows:

[0063] 1) Specific energy: 0.2C charge-discharge under 25℃ environment.

[0064] 2) Needle test: the battery was radially punctured by a steel needle with a diameter of 3mm and a taper of 30° at a speed of 40mm / s when the battery was in a full state (100% SOC), and the steel needle stayed in the battery for 1h.

[0065]

[0066] 3) Extrusion test: the battery in a full state was placed between two steel plates of a press machine. From the initial contact point, extrusion was carried out at an initial speed of about 1.5cm / s until the pressure was not less than 13kN or the voltage of the sample was reduced to less than 2 / 3 of the original.

[0067] Table 1: Test results of batteries

[0068]

[0069]

[0070] wherein n / 10 means that n samples in 10 battery samples of each batch passed the test.

[0071] By comparing the batteries 1-3 and the battery 6 prepared in comparative example 1, it can be seen that the more uniform addition of LATP can effectively improve the safety of the lithium ion battery and increase the probability of overcharge extrusion and needle puncture of the battery.

[0072] The above embodiments of the present application are described in detail, but the content described is only the preferred embodiments of the present application, and cannot be considered as limiting the scope of the present application. Any equivalent changes and improvements made according to the scope of the present application should still belong to the scope of the present application.​

Claims

1. A preparation method of a high-nickel ternary positive electrode material containing LATP, characterized in that: The method comprises the following steps: ​ Step 1: Dissolve a nickel source, a cobalt source, a manganese source or an aluminum source and a lithium source in water, add a complexing agent and a LATP aqueous nano slurry, and mix uniformly; Step 2: continuously stir the above mixture under heating until a gel is formed; Step 3: dry the gel at 80-200℃ and then grind into powder; Step 4: sinter the powder at 300-600℃ to obtain a high-nickel ternary positive electrode material prepared from the LATP aqueous nano slurry.

2. The preparation method of the high-nickel ternary positive electrode material containing LATP according to claim 1, The molar ratio of lithium, nickel, cobalt, manganese or aluminum is 1.03:0.5:0.2:0.3-1.05:0.9:0.05:0.

05. The magnesium salt and / or the titanium salt are doped in step 1.

3. The preparation method of the high-nickel ternary positive electrode material containing LATP according to claim 1, characterized in that: The metal salt is a mixture of one or more of a sulfate, a nitrate and a chloride.

4. The preparation method of the high-nickel ternary positive electrode material containing LATP according to claim 1 or 3, characterized in that: The complexing agent is one or more of citric acid, EDTA and ammonia, and the addition amount is 1-2 times the total molar amount of metal ions.

5. The preparation method of the high-nickel ternary positive electrode material containing LATP according to claim 1, characterized in that: The particle size of the LATP aqueous slurry is 70-100 nm, and the mass of the LATP is 0.5%-2% of the mass of the high-nickel ternary positive electrode material.

6. The preparation method of the high-nickel ternary positive electrode material containing LATP according to claim 1, characterized in that: The heating temperature in step 2 is 60-100℃.

7. The preparation method of the high-nickel ternary positive electrode material containing LATP according to claim 1, characterized in that:

8. The high-nickel ternary positive electrode material containing LATP prepared by the method of any one of claims 1-7. The positive electrode slurry is prepared from the high-nickel ternary positive electrode material containing LATP of claim 8.

9. A battery positive electrode, characterized by: The battery positive electrode comprises the positive electrode of claim 9.

10. A lithium-ion battery, characterized by: The battery positive electrode comprises the positive electrode of claim 9.

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