A composite material modified ternary cathode material and its preparation method and application

Abstract

The present invention discloses a method for preparing a composite material modified ternary cathode material, comprising: preparing a first material Li by solid phase sintering; 2x‑4 ZrO x , of which 2

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery materials, and particularly to a composite material modified ternary cathode material, its preparation method and application. Background Art

[0002] With the wide application and rapid development of lithium batteries, people's requirements for the performance of lithium-ion batteries are also getting higher and higher; the performance of lithium-ion secondary batteries is mainly determined by their cathode materials.

[0003] Ternary materials are increasingly used as cathode materials for lithium batteries due to their high energy density, environmental friendliness and good safety performance; however, when ternary materials are used as cathode materials, they are in direct contact with the electrolyte, and side reactions will occur between the ternary materials and the electrolyte; this causes the ternary materials to decay, resulting in a decline in the performance of lithium batteries. On the other hand, the working voltage of ternary cathode materials will decay as the time spent in a high-temperature environment increases; but in the actual application of batteries, it is inevitable to charge and discharge for a long time in a high-temperature environment. This characteristic severely limits the application of ternary cathode materials in high-temperature environments.

[0004] Therefore, it is very important to reduce the voltage drop of ternary cathode materials at high temperatures; improve their working efficiency in high-temperature environments; and improve their stability. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a composite material modified ternary cathode material, its preparation method and application, which can reduce the voltage drop of ternary cathode materials at high temperatures; improve their working efficiency in high-temperature environments.

[0006] To solve the above technical problem, the present invention provides a preparation method for a composite material modified ternary cathode material, the preparation method includes: preparing a first material by solid-phase sintering, the chemical formula of the first material is Li 2x-4 ZrO x , where 2 < x ≤ 6; adding a second material to deionized water to obtain a first mixed solution, the second material is a carbon-containing material; adding the first material to the first mixed solution to obtain a second mixed solution; performing a first material modification operation on the second mixed solution to obtain the composite material, the composite material is the second material wrapping the first material; adding the composite material and a silane coupling agent to an organic solvent to obtain a third mixed solution; adding the ternary cathode material to the third mixed solution to obtain a target mixed solution; performing a second material modification operation on the target mixed solution to obtain the composite material modified ternary cathode material.

[0007] In a feasible implementation, the second material is at least one of graphite, activated carbon, carbohydrate, acetylene black, mesoporous carbon, graphene, or carbon nanotubes.

[0008] In a feasible implementation, the first material modification operation includes: transferring the second mixed solution into a reactor, reacting at 120-140° C. for 1-3 hours; cooling to room temperature, and then washing, centrifuging, and drying to obtain a precursor composite material.

[0009] In a feasible implementation, the first material modification operation further includes: sintering and carbonizing the precursor composite material under an inert protective gas, and grinding and screening to obtain the composite material.

[0010] In a feasible implementation, the mass ratio of the first material, the silane coupling agent, the organic solvent and the ternary positive electrode material is 0.1-0.3:0.01-0.1:50-100:10-50.

[0011] In a feasible implementation, the added mass ratio of the second material to the first material is (0.002-0.3):1.

[0012] In a feasible implementation, the second material modification operation includes: ultrasonically dispersing the target mixed liquid to obtain a target dispersion liquid, and heating to remove the organic solvent in the target dispersion liquid; the ultrasonic dispersion time is 1 hour to 20 hours.

[0013] In a feasible implementation, the solid-phase sintering temperature of the first material is 900° C.-1000° C., and the holding time is 5 h-20 h.

[0014] Correspondingly, the present invention also provides a composite material modified ternary cathode material, wherein the composite material modified ternary cathode material is prepared by any one of the above-mentioned methods for preparing the composite material modified ternary cathode material.

[0015] Correspondingly, the present invention also provides a lithium battery, which includes the composite material modified ternary positive electrode material as described above.

[0016] The implementation of the present invention has the following beneficial effects:

[0017] The second material containing carbon is coated on the first material Li 2x-4 ZrO x A composite material is formed, and the composite material is used to modify the ternary positive electrode material. The lithium battery prepared using the ternary positive electrode material modified with the composite material can maintain a higher voltage value in a high temperature environment, thereby improving the working efficiency of the lithium battery in a high temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 SEM image of the composite material modified ternary cathode material prepared in Example 1. Specific Embodiments

[0019] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following detailed description of the specific embodiments of the present invention will be given in conjunction with the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0021] On the one hand, the present application provides a method for preparing a composite material modified ternary cathode material. When the composite material modified ternary cathode material prepared by this method is applied to a lithium battery, it can avoid side reactions between the ternary material and the electrolyte. At the same time, it can also reduce the attenuation of the working voltage of the lithium battery in a high-temperature environment. The method for preparing the composite material modified ternary cathode material described in the present application includes the following steps:

[0022] Prepare a first material by solid-phase sintering. The chemical formula of the first material is Li 2x-4 ZrO x , where 2 < x ≤ 6. Prepare the first material Li 2x-4 ZrO x, the first material of the target size can be prepared at a low cost, saving the time and other production costs associated with traditional preparation methods such as ball milling or sand milling. Optionally or preferably, the solid-phase sintering temperature of the first material is 900°C-1000°C, and the holding time is 5-20 hours. A second material is added to deionized water to obtain a first mixed solution, wherein the second material is a carbonaceous material. The first material is added to the first mixed solution to obtain a second mixed solution. The second mixed solution is subjected to a modification operation with the first material to obtain the composite material, wherein the composite material comprises the first material encapsulated by the second material. Using a carbonaceous material to encapsulate the first material not only improves electrolyte isolation but also increases the conductivity of the modified second material, i.e., the composite material, thereby preventing it from affecting the conductivity of the composite-modified ternary cathode material. Optionally or preferably, the second material can be at least one of graphite, activated carbon, carbohydrates, acetylene black, mesoporous carbon, graphene, or carbon nanotubes. Optionally or preferably, the second material can be activated carbon. The composite material and a silane coupling agent are added to an organic solvent to obtain a third mixed solution. The ternary cathode material is added to the third mixed solution to obtain a target mixed solution. The target mixed solution is subjected to a second material modification operation to obtain the composite material modified ternary cathode material. Optionally or preferably, the mass ratio of the first material, the silane coupling agent, the organic solvent, and the ternary cathode material is 0.1-0.3:0.01-0.1:50-100:10-50. Optionally or preferably, the mass ratio of the second material to the first material is (0.002-0.3):1.

[0023] Optionally or preferably, the first material modification operation may include: transferring the second mixed liquid into a reactor, reacting at 120-140°C for 1-3 hours; cooling to room temperature, washing, centrifuging, and drying to obtain a precursor composite material. The sample cooled to room temperature may be washed with deionized water or alcohol, or may be washed with deionized water first and then with alcohol. Optionally or preferably, the first material modification operation may also include: sintering and carbonizing the precursor composite material under an inert protective gas, grinding and sieving to obtain the composite material. The inert gas may be nitrogen, argon or oxygen, and the gas flow rate is 0.1m 3 / S-1m 3 / S.

[0024] Optionally or preferably, the second material modification operation may include: ultrasonically dispersing the target mixed liquid to obtain a target dispersion liquid, and heating to remove the organic solvent in the target dispersion liquid; the ultrasonic dispersion time may be 1 hour to 20 hours.

[0025] On the other hand, the present application also provides a ternary positive electrode material modified with a composite material, which is prepared by the aforementioned preparation method.

[0026] The present application also provides a lithium battery, comprising a positive electrode and a negative electrode, wherein the positive electrode material is a ternary positive electrode material modified with a composite material prepared by the aforementioned method.

[0027] In order to further understand the present application, the composite material modified ternary cathode material and the preparation method thereof provided in the present application are described in detail below in conjunction with the examples.

[0028] Example 1

[0029] The first material, Li2ZrO3, was prepared by solid-phase sintering. Lithium carbonate was used as the lithium source, and zirconium oxide was used as the zirconium source. The lithium carbonate and zirconium oxide were mixed and heated to 1000°C for 10 hours. After the solid-phase sintered product cooled naturally, it was removed and pulverized to produce a white powder with an average particle size of approximately 3μm. Its pH was measured to be 11.6.

[0030] A second material is added to deionized water to obtain a first mixed solution, wherein the second material is a carbonaceous material; in this embodiment, activated carbon is selected as the second material.

[0031] The first material, Li2ZrO3, prepared above, was then added to the first mixed solution to obtain a second mixed solution, wherein the weight of the second material added was 0.2% of the first material. The second mixed solution was transferred to a reactor and reacted at 120°C for one hour. After cooling naturally to room temperature, the mixture was washed, centrifuged, and dried to obtain a precursor composite material. This precursor composite material consisted of the first material encapsulated by the second material.

[0032] The resulting composite precursor, obtained through centrifugal drying, was then sintered and carbonized under an inert protective atmosphere of nitrogen. In this example, the sintering temperature was 500°C and the sintering time was 5 hours. After natural cooling, the composite precursor was ground and sieved in a ball mill to obtain a carbonized composite material. The ball mill speed was set at 180 rpm and the milling time was 2 hours. The composite precursor was then sieved through a 300-mesh sieve to obtain a uniform particle size.

[0033] Finally, the precursor composite material prepared above is coupled with the ternary cathode material via a silane coupling agent to obtain a ternary cathode material modified with the treated precursor composite material. The specific preparation process is as follows:

[0034] First, the precursor composite material and the silane coupling agent KH-570 are added to the organic solvent N-methylpyrrolidone. After stirring the two together, the ternary cathode material is added and stirred. The mixture is then ultrasonically dispersed to disperse the two more evenly in the solution; the ultrasonication time is 2 hours. After ultrasonic treatment, the mixture is placed in a vacuum oven to heat and remove the organic solvent. The drying temperature is set to 150°C under vacuum and the drying time is 24 hours. Finally, a uniformly dispersed composite material modified ternary cathode material is obtained. In this embodiment, the mass ratio of the first material, KH-570, organic solvent, and ternary cathode material is 0.1:0.02:50:20.

[0035] like Figure 1 The morphology of the ternary cathode material modified with this composite material is shown. The material is granular, resembling pebbles. Scanning electron microscopy (SEM) reveals uniform distribution of the powder and consistent particle size. To test the performance of this ternary cathode material as a battery cathode before and after modification, a half-cell was prepared using it as the battery cathode. Temperature rise and voltage drop experiments were conducted on this material and the unmodified ternary material as the battery cathode.

[0036] The specific preparation process is as follows:

[0037] The unmodified ternary positive electrode material was added as the positive electrode material as a comparative example, and the ternary positive electrode material modified with a composite material was used as an example. Both were prepared into batteries and tested. The conditions for preparing the batteries were controlled to be the same, specifically: the components (ternary positive electrode material or ternary positive electrode material modified with a composite material), carbon black, and adhesive were mixed evenly in a mass ratio of 8:1:1, coated on an aluminum foil current collector to make a battery positive electrode sheet, and a lithium sheet was used as the negative electrode. The batteries were prepared and various performance tests were performed. The temperature rise and voltage drop test process is to first test the battery voltage before high temperature, then place the battery in a high temperature environment for different time periods; then test its voltage value after high temperature, and compare the voltage values ​​before and after high temperature tests; to avoid the randomness of the test, 15 groups of batteries were prepared for the comparative example and the example, respectively, and tested under the same working environment, and the average values ​​were taken for comparison. The test data are shown in Tables 1 and 2.

[0038]

[0039] Table 1

[0040]

[0041] Table 2

[0042] As shown in Tables 1 and 2, the average voltage drop in the comparative example group at 100°C for 24 hours was 2.5553, a 60% drop rate. Under the same high-temperature conditions, the average voltage drop in the example group was 1.2861, a 30% drop rate. This indicates that batteries fabricated with composite-modified ternary cathode materials exhibit a lower voltage drop over extended periods of high temperature. Therefore, composite-modified ternary cathode materials offer significant improvements in high-temperature applications, reducing self-discharge voltage loss.

[0043] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a composite material modified ternary cathode material, characterized in that: The preparation method comprises: The first material is prepared by solid phase sintering, wherein the chemical formula of the first material is Li 2x-4 ZrO x , of which 2 <x≤6; adding a second material to deionized water to obtain a first mixed solution, wherein the second material is a carbonaceous material; adding the first material to the first mixed liquid to obtain a second mixed liquid; Transferring the second mixed liquid into a reactor and reacting it at 120-140° C. for 1-3 hours; cooling it to room temperature, washing it, centrifuging it, and drying it to obtain a precursor composite material; sintering and carbonizing the precursor composite material under an inert protective gas, grinding and sieving it to obtain a composite material; the composite material is the first material wrapped by the second material; adding the composite material and the silane coupling agent into an organic solvent to obtain a third mixed solution; adding the ternary cathode material to the third mixed solution to obtain a target mixed solution; The target mixed liquid is ultrasonically dispersed to obtain a target dispersion liquid, and the organic solvent in the target dispersion liquid is removed by heating to obtain the ternary cathode material modified by the composite material.

2. The preparation method according to claim 1, characterized in that The second material is at least one of graphite, activated carbon, carbohydrate, acetylene black, mesoporous carbon, graphene or carbon nanotube.

3. The preparation method according to claim 1, characterized in that The mass ratio of the first material, the silane coupling agent, the organic solvent and the ternary positive electrode material is 0.1-0.3:0.01-0.1:50-100:10-50.

4. The preparation method according to claim 1, characterized in that The added mass ratio of the second material to the first material is (0.002-0.3):

1.

5. The preparation method according to claim 1, characterized in that The ultrasonic dispersion time is 1 h to 20 h.

6. The preparation method according to claim 1, characterized in that The solid-phase sintering temperature of the first material is 900° C.-1000° C., and the holding time is 5 h-20 h.

7. A composite material modified ternary cathode material, characterized in that: The composite material is prepared by the preparation method of the composite material modified ternary positive electrode material according to any one of claims 1 to 6.

8. A lithium battery, characterized in that: The lithium battery comprises the composite material modified ternary cathode material as claimed in claim 7.

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