Mixing Method for Cathode Material of Lithium-Ion Battery

Abstract

The present invention provides a method for mixing cathode materials of lithium-ion batteries, which comprises the following steps: putting the cathode materials of lithium-ion batteries to be mixed into the tank body of a ball mill; then adding a dry organic aluminum preparation into the tank body for ball milling and mixing to obtain a mixed material; pouring the mixed material onto a sieve to separate the ball milling beads in the mixed material, so as to obtain the mixed cathode materials of lithium-ion batteries. The mixing method provided by the present invention effectively solves the problems of material hanging and residual materials during the dry mixing of cathode materials of lithium-ion batteries. Meanwhile, the process is simplified, the operation difficulty is reduced, there is no need for an additional cleaning step after cleaning like other solvent-containing cleaners, and there is no need for separate cleaning after mixing, saving manpower and improving efficiency.

Description

Technical Field

[0001] The present invention relates to the field of treating cathode materials for lithium-ion batteries, and more particularly, to a method for mixing cathode materials for lithium-ion batteries. Background Art

[0002] Ternary materials and lithium iron phosphate materials are commonly used cathode materials for lithium-ion batteries. During the preparation of the cathode for lithium-ion batteries, it is usually necessary to pre-mix the ternary materials and lithium iron phosphate materials by dry mixing, and a ball mill is mostly used for mixing. However, because the mixing equipment for these materials in the laboratory or production will involve the problem of remaining materials and adhering materials after each batch of mixing is completed. If some are accumulated in each batch, it will seriously affect the product quality in the end. Especially when using a ball mill for mixing, the problem of adhering materials is more obvious.

[0003] Existing cleaning agents, such as the cleaning agent composition disclosed in Patent 201480033437.3, are mostly cleaning agents that require solvents. They need to be rinsed after cleaning, and their application range is relatively wide and the pertinence is not strong. Therefore, it is necessary to provide a cleaning method applied to the dry mixing stage of ternary materials and lithium iron phosphate materials to more effectively solve the problems of adhering materials and remaining materials during the dry mixing of ternary materials and lithium iron phosphate materials, and at the same time take into account aspects such as simple process and easy operation. Summary of the Invention

[0004] The main object of the present invention is to provide a method for mixing cathode materials for lithium-ion batteries to solve the problems of adhering materials and remaining materials during the dry mixing of cathode materials for lithium-ion batteries in the prior art, and at the same time simplify the process and reduce the operation difficulty.

[0005] To achieve the above object, according to one aspect of the present invention, there is provided a method for mixing cathode materials for lithium-ion batteries, which includes the following steps: putting the cathode materials for lithium-ion batteries to be mixed into the tank body of a ball mill; then adding a dry organic aluminum preparation into the tank body for ball milling and mixing to obtain a mixed material; pouring the mixed material onto a sieve to separate the ball milling beads in the mixed material to obtain the mixed cathode materials for lithium-ion batteries.

[0006] Further, the dry organic aluminum preparation is aluminum butoxide and / or aluminum isopropoxide.

[0007] Further, the addition amount of the dry organic aluminum preparation is 0.02-0.08 wt% of the addition amount of the cathode materials for lithium-ion batteries to be mixed.

[0008] Further, the cathode materials for lithium-ion batteries to be mixed include ternary cathode materials and lithium iron phosphate materials.

[0009] Furthermore, the weight ratio of the ternary cathode material to the lithium iron phosphate material is 1.02 - 1.06:1.

[0010] Furthermore, in the step of ball milling and mixing, the weight ratio of the ball milling beads to the lithium-ion battery cathode material to be mixed is 1 - 3:1.

[0011] Furthermore, in the step of grinding and mixing, the rotation speed of the tank body is 400 - 500 r / min, and the mixing time is 20 - 120 min.

[0012] Furthermore, the ball milling beads are zirconium balls.

[0013] Furthermore, before the step of ball milling and mixing, the method further includes a premixing step, which includes: shaking the tank body up and down to repeatedly invert the materials inside the tank body.

[0014] Furthermore, the mesh number of the sieve is 30 - 50 meshes.

[0015] The present invention provides a method for mixing lithium-ion battery cathode materials. After putting the lithium-ion battery cathode materials to be mixed into the tank body of a ball mill, a dry organic aluminum preparation is added thereto as a dry cleaning agent at the same time, so that the lithium-ion battery cathode materials participate in the ball milling and mixing together. After the ball milling is completed, the mixed materials are poured onto a sieve to separate the grinding balls, and the mixed lithium-ion battery cathode materials are obtained. Since the organic aluminum preparation as the dry cleaning agent directly participates in the ball milling and mixing, it will make the inner wall of the ball mill and the ball milling beads smooth during the ball milling and dispersion process. There is basically no material hanging on the wall, and there is no adhesion between the bottom material, the ball milling beads and the materials, which plays a self-cleaning role. Therefore, it is suitable for continuous mixing. It should be noted in the specification that because an organic aluminum preparation is used, there will be a trace amount of aluminum residue after using this dry cleaning agent. And since during the firing process of the lithium-ion battery cathode materials (especially ternary materials and lithium iron phosphate materials), aluminum doping needs to occur on the surface of the materials, the remaining trace amount of aluminum just plays the role of aluminum coating on the surface of the materials, improving the stability of the materials.

[0016] In summary, the method for mixing lithium-ion battery cathode materials provided by the present invention effectively solves the problems of material hanging and remaining materials during the dry mixing of lithium-ion battery cathode materials, simplifies the process, reduces the operation difficulty, does not require an additional cleaning step after cleaning like other solvent-containing cleaning agents, and does not require separate cleaning after mixing, saving manpower and improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 The internal photo of the ball mill after mixing the cathode material of the lithium-ion battery in Embodiment 1 of the present invention is shown;

[0019] Figure 2 The internal photo of the ball mill after mixing the cathode material of the lithium-ion battery in Embodiment 2 of the present invention is shown;

[0020] Figure 3 and Figure 4 The internal photo of the ball mill after mixing the cathode material of the lithium-ion battery without adding the dry-type organic aluminum preparation in Comparative Example 1 is shown. Detailed implementation manners

[0021] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0022] As described in the background art section, there are problems of material hanging and remaining materials during the dry mixing of the cathode material of the lithium-ion battery in the prior art. To solve this problem, the present invention provides a method for mixing the cathode material of the lithium-ion battery, which includes the following steps: putting the cathode material of the lithium-ion battery to be mixed into the tank body of the ball mill; then adding the dry-type organic aluminum preparation into the tank body for ball milling and mixing to obtain a mixed material; pouring the mixed material onto a sieve to separate the ball milling beads in the mixed material, so as to obtain the mixed cathode material of the lithium-ion battery.

[0023] The present invention provides a method for mixing the cathode material of the lithium-ion battery. After putting the cathode material of the lithium-ion battery to be mixed into the tank body of the ball mill, a dry-type organic aluminum preparation is added thereto as a dry cleaner at the same time, so that the cathode material of the lithium-ion battery participates in the ball milling and mixing together. After the ball milling is completed, the mixed material is poured onto a sieve to separate the grinding balls, so as to obtain the mixed cathode material of the lithium-ion battery. Since the organic aluminum preparation as the dry cleaner directly participates in the ball milling and mixing, it will make the inner wall of the ball mill and the ball milling beads smooth during the ball milling and dispersion process. There is basically no material hanging on the wall, and there is no adhesion phenomenon between the bottom material ball milling beads and the material, which plays a self-cleaning role. Therefore, it is applicable to continuous mixing. And it should be noted in the specification that because the organic aluminum preparation is used, there will be trace aluminum residues after using this dry cleaner. And during the firing process of the cathode material of the lithium-ion battery (especially ternary materials and lithium iron phosphate materials), aluminum doping needs to occur on the surface of the material. Therefore, the remaining trace aluminum just plays the role of aluminum coating on the surface of the material, improving the stability of the material.

[0024] In summary, the lithium-ion battery positive electrode material mixing method provided by the present invention effectively solves the problems of hanging material and residual material during dry mixing of lithium-ion battery positive electrode materials, while simplifying the process and reducing the difficulty of operation. There is no need for additional cleaning steps after cleaning like other solvent-containing cleaners, and there is no need for separate cleaning after mixing, which saves manpower and improves efficiency.

[0025] The above mixing method is applicable to lithium-ion battery positive electrode materials, especially ternary positive electrode materials (such as LiNi 1-x- y Co x Mn y O 2 , x is less than 1 and greater than 0, y is less than 1 and greater than 0, x+y is less than 1) and lithium iron phosphate material LiFePO 4 .

[0026] In a preferred embodiment, the dry organic aluminum preparation is aluminum n-butoxide and / or aluminum isopropoxide. These two organic aluminum preparations have better cleaning effects, and aluminum n-butoxide and aluminum isopropoxide can be purchased commercially or made at home.

[0027] In order to further improve the cleaning effect of the inside of the ball mill during the mixing process and avoid adding too much dry cleaning agent, in a preferred embodiment, the amount of dry organic aluminum preparation added is 0.02 to 0.08 wt % of the amount of lithium ion battery positive electrode material to be mixed.

[0028] In a preferred embodiment, the weight ratio of the ternary cathode material to the lithium iron phosphate material is 1.02 to 1.06:1. More preferably, in the step of ball milling and mixing, the weight ratio of the ball milling beads to the lithium ion battery cathode material to be mixed is 1:1. This is more conducive to the mixing of the ternary cathode material and the lithium iron phosphate material. Further preferably, in the step of grinding and mixing, the rotation speed of the tank is 400 to 500 r / min, and the mixing time is 20 to 120 min.

[0029] In a preferred embodiment, the ball milling beads are zirconium balls. The use of zirconium balls can make the ball milling process more complete, and the adhesion between the material and the zirconium balls is weaker, which is more conducive to avoiding the phenomenon of material hanging.

[0030] In order to further improve the mixing effect, in a preferred embodiment, before the ball milling mixing step, the method further includes a premixing step, which includes: shaking the tank body up and down to repeatedly invert the material inside the tank body. In this way, the materials can be premixed before the ball milling mixing, which is more conducive to uniform mixing of the materials.

[0031] More preferably, the mesh size of the sieve is 50 mesh.

[0032] In summary, the mixing method provided by the present invention is simple to operate and convenient to use. The dry-type organic aluminum preparation is used as a dry-type cleaning agent, and the amount of materials used is extremely small. This dry-type cleaning agent is applied to clean the inner wall of the material tank during the dry material ball milling process. It is added before mixing. After mixing for a period of time, the material is transferred. There is no material hanging on the inner wall, and there is no bottom material residue at the bottom of the tank, which speeds up the material transfer efficiency, reduces the cleaning process, and improves the material transfer and residual material cleaning rate. Therefore, the present invention can continuously carry out the mixing function, avoid bottom material residue, and reduce the adverse impact on the results caused by the accumulation of residual materials in this process. After using this dry-type cleaning agent, there will be a trace amount of aluminum residue. Since aluminum doping needs to occur on the surface of the material during the firing process of the ternary material and lithium iron phosphate material, the remaining trace amount of aluminum just plays the role of aluminum coating on the surface of the material, improving the stability of the material.

[0033] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0034] Example 1

[0035] (1) Preparation of the dry-type cleaning agent: Using isopropanol and high-purity aluminum as raw materials, and tri-n-propylaluminum and aluminum isopropoxide as initiators, the organic aluminum preparation is prepared by initiation. The specific steps are to mix isopropanol and aluminum particles in a molar ratio of 3:1, stir slowly, and then slowly drop tri-n-propylaluminum and aluminum isopropoxide to initiate the reaction. The total amount of tri-n-propylaluminum and aluminum isopropoxide as initiators is 0.1% of the molar amount of the high-purity aluminum material. React for 30 minutes. After the initiation is completed, continue to heat and react for 1.5 hours until the reaction solution reacts completely. After the reaction is complete, recrystallize, filter by suction, and vacuum dry to obtain the high-purity dry-type cleaning agent, organic aluminum preparation, and aluminum isopropoxide.

[0036] (2) Application to the ternary material mixing process: First, add 150 g of black powder ternary precursor (Ni 0.6 Co 0.2 Mn 0.2 )OH 2 to the ceramic tank, then add 65.96 g of battery-grade lithium carbonate to the ball milling tank according to a ratio of 1:1.06, and then add this organic aluminum preparation according to a ratio of 0.05% of the total weight. Add 0.4 cm zirconia balls according to a ratio of 1:1 of the total material weight. After all the materials are put into the tank, use the premixing operation. First, shake the tank up and down, invert the materials repeatedly, and repeat 5 times to initially disperse the materials in the tank and make them generally uniform. Gradually start the mixing device, and make the mixing tank rotate unidirectionally at a rate of 400 revolutions / min for at least 20 minutes.

[0037] (3) Material handling: After mixing, pass the material through a 50-mesh sieve. Invert the tank body until it is nearly vertical, leaving the zirconium balls on the sieve. Gently shake the sieve to remove a small amount of material accumulated above the zirconium balls, and then pour the zirconium balls into the ball mill tank. As Figure 1 shown, the tank body is clean and bright, without residual material, and there is no material hanging on the inner wall of the tank. Some of the zirconium balls used in ball milling have returned to their original white color, with a relatively smooth surface. They can be reused with good retention, and the next batch of material mixing can be directly carried out without cleaning the bottom material.

[0038] Example 2

[0039] (1) Preparation of dry cleaner: Using n-butanol and high-purity aluminum as raw materials, and tri-n-propylaluminum and aluminum butoxide as initiators, initiate the preparation to obtain this organoaluminum preparation. The specific steps are to mix n-butanol and aluminum particles in a molar ratio of 3:1, stir slowly, and then slowly drop in tri-n-propylaluminum and aluminum butoxide to initiate the reaction. The total amount of tri-n-propylaluminum and aluminum butoxide as initiators is 0.1% of the molar amount of the high-purity aluminum material. React for 30 minutes. After the initiation is completed, continue to heat and react for 1.5 hours until the reaction solution reacts completely. After the reaction is complete, through recrystallization, filtration, and vacuum drying, the high-purity dry cleaner, organoaluminum preparation, and aluminum butoxide are obtained.

[0040] (2) Application to the lithium iron phosphate mixing process: First, add 100 g of FePO 4 to the ceramic tank body, then add 25 g of battery-grade lithium carbonate to the ball mill tank body according to a lithium-iron ratio of 1.02, and then add this organoaluminum preparation according to a ratio of 0.04% of the total weight. Add 0.4 cm zirconium balls according to a ratio of 1:1 of the total material weight. After all the materials are put into the tank body, use the premixing operation. First, shake the tank body up and down, invert the materials repeatedly, and repeat 5 times to preliminarily disperse the materials in the tank, and the dispersion is generally uniform. Gradually start the mixing device, and make the mixing tank rotate unidirectionally at a rate of 500 revolutions per minute for at least 60 minutes.

[0041] (3) Material handling: After mixing, pass the material through a 50-mesh sieve. Invert the tank body until it is nearly vertical, leaving the zirconium balls on the sieve. Gently shake the sieve to remove a small amount of material accumulated above the zirconium balls, and then pour the zirconium balls into the ball mill tank. As Figure 2 shown, the tank body is clean and bright, without residual material, and there is no material hanging on the inner wall of the tank. Some of the zirconium balls used in ball milling have returned to their original white color, with a relatively smooth surface. They can be reused with good retention and can be directly used for the next batch of material mixing.

[0042] Comparative Example 1

[0043] (1) First, add the black powder ternary precursor (Ni 0.6 Co 0.2 Mn 0.2 )OH to the ceramic tank body2 150 g, and then add 65.96 g of battery-grade lithium carbonate into the ball-milling tank body at a ratio of 1:1.06, and add zirconium balls with a diameter of 0.4 cm at a ratio of 1:1 based on the total weight of the materials. After all the materials are placed in the tank body, use the premixing operation. First, shake the tank body up and down, invert the materials repeatedly, and repeat 5 times to preliminarily disperse the materials in the tank and make the dispersion generally uniform. Gradually start the mixing device to make the mixing tank rotate unidirectionally at a rate of 400 revolutions per minute for at least 20 minutes.

[0044] (2) Material treatment: After mixing, pass the materials through a 50-mesh sieve. Invert the tank body close to vertical, and the zirconium balls remain on the sieve. Gently shake the sieve to remove a small amount of accumulated materials above the zirconium balls, and then pour the zirconium balls back into the ball-milling tank. As Figure 3 and 4 shown, there is a phenomenon of material sticking inside the tank body, and a large amount of bottom material adheres to the zirconium balls used in ball milling.

[0045] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for mixing cathode materials of a lithium-ion battery, characterized in that, it comprises the following steps: Put the cathode materials of the lithium-ion battery to be mixed into the tank body of a ball mill; the cathode materials of the lithium-ion battery to be mixed include ternary cathode materials and lithium iron phosphate materials, and the weight ratio of the ternary cathode materials to the lithium iron phosphate materials is 1.02 - 1.06:1; Then add a dry organic aluminum preparation to the tank body for ball milling and mixing to obtain a mixed material; the dry organic aluminum preparation is aluminum butoxide; the addition amount of the dry organic aluminum preparation is 0.02 - 0.08 wt% of the addition amount of the cathode materials of the lithium-ion battery to be mixed; Pour the mixed material onto a sieve to separate the ball milling beads in the mixed material, and obtain the mixed cathode materials of the lithium-ion battery.

2. The method for mixing cathode materials of a lithium-ion battery according to claim 1, characterized in that, in the step of ball milling and mixing, the weight ratio of the ball milling beads to the cathode materials of the lithium-ion battery to be mixed is 1 - 3:

1.

3. The method for mixing cathode materials of a lithium-ion battery according to claim 2, characterized in that, in the step of ball milling and mixing, the rotation speed of the tank body is 400 - 500 r / min, and the mixing time is 20 - 120 min.

4. The method for mixing cathode materials of a lithium-ion battery according to claim 3, characterized in that, the ball milling beads are zirconium balls.

5. The method for mixing cathode materials of a lithium-ion battery according to claim 1, characterized in that, before the step of ball milling and mixing, the method further includes a premixing step, which includes: shaking the tank body up and down to repeatedly invert the materials inside the tank body.

6. The method for mixing cathode materials of a lithium-ion battery according to claim 1, characterized in that, the mesh number of the sieve is 30 - 50 meshes.

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