Positive electrode material, preparation method thereof, positive electrode sheet, battery, and electric device

Abstract

The application discloses a positive electrode material, a preparation method thereof, a positive electrode sheet, a battery and a power utilization device. The positive electrode material comprises a ternary NCM material, and the surface of the ternary NCM material is coated with Co 2+ / conductive polymer material to form a modified ternary NCM material. In the application, Co 2+ is compounded with the conductive polymer on the ternary NCM material, which not only improves the cycle performance of the battery, but also enhances the peeling strength of the electrode sheet, and the optimization effects of Co 2+ and the conductive polymer on the battery performance are synergistically enhanced.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a positive electrode material and its preparation method, a positive electrode sheet, a battery, and an electrical device. Background Technology

[0002] With the rapid development of the new energy industry, the demand for high energy density power batteries is increasing. Therefore, improving the energy density of lithium-ion batteries has become a current focus. Currently, ternary high-nickel NCM materials are gradually replacing traditional LCO materials as the preferred cathode material for lithium batteries.

[0003] Ternary NCM materials are composed of Ni, Co, and Mn elements. Ni can improve battery capacity; Co can effectively stabilize the layered structure of ternary materials and suppress cation mixing issues; the presence of Mn can reduce costs, and since it does not participate in chemical reactions during charge-discharge cycles, it can stabilize the material structure and increase battery safety. NCM811 cathode material contains a high proportion of Ni (80%), which can easily lead to structural instability. Therefore, improving the structural stability of the material while ensuring high capacity is of paramount importance. Summary of the Invention

[0004] The purpose of this invention is to provide a positive electrode material and its preparation method, a positive electrode sheet, a battery, and an electrical device to improve the cycle performance of the battery.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0006] A first aspect of this application provides a cathode material, said cathode material comprising a ternary NCM material, the surface of which is coated with Co. 2+ Conductive polymer materials are used to form modified ternary NCM materials.

[0007] The second aspect of this application provides a method for preparing a cathode material, which involves mixing and reacting a ternary NCM, a cobalt-containing material, and a conductive polymer to prepare a modified ternary NCM material.

[0008] To optimize the above technical solution, the specific measures also include:

[0009] The reaction process involves mixing the reactants ternary NCM, cobalt-containing materials, and conductive polymer in water, and then reacting them at a high temperature of 180°C.

[0010] The reaction is carried out at -200℃ for 20-24 hours.

[0011] The conductive polymer is at least one of poly(3,4-ethylenedioxythiophene), polyaniline, polypyrrole, and poly(p-styrene).

[0012] Preferably, the conductive polymer is poly(3,4-ethylenedioxythiophene), and the mass ratio of the ternary NCM to poly(3,4-ethylenedioxythiophene) is in the range of 30 to 34:1, forming Co on the surface of the ternary NCM material. 2+ / PEDOT.

[0013] The cobalt-containing material is at least one of cobalt sulfate, cobalt chloride, cobalt hydroxide, and cobalt carbonate.

[0014] Preferably, the cobalt-containing material is cobalt sulfate, and the mass ratio of the ternary NCM to CoSO4·7H2O is in the range of 16–20:1.

[0015] A third aspect of this application provides a positive electrode sheet, the positive electrode sheet comprising a positive electrode active material, the positive electrode active material comprising the positive electrode material described in the first aspect of this application or the positive electrode material prepared by the method described in the second aspect of this application.

[0016] The fourth aspect of this application provides a battery that uses the positive electrode sheet described in the third aspect of this application.

[0017] The fifth aspect of this application provides an electrical device that uses the battery described in the fourth aspect of this application.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] The cathode material of the present invention contains a surface coated with Co. 2+ / Modified ternary NCM materials of conductive polymers, Co 2 + The introduction of [a specific ingredient] stabilizes the structure of the ternary NCM material, thereby improving battery safety; the introduction of conductive polymers can improve the conductivity of the material.

[0020] Furthermore, this application also discovered that introducing a conductive polymer improves the electrode peel strength between the positive electrode material and the foil. Experimental verification shows that this application utilizes Co... 2+ Composites of conductive polymers onto ternary NCM materials not only improve battery cycle performance but also enhance electrode peel strength, and Co... 2+ The combined effect of the conductive polymer and the battery performance optimization is synergistic. Attached Figure Description

[0021] Figure 1 : Schematic diagram of the preparation process of the present invention.

[0022] Figure 2 Example 1 of this invention prepared a Co-coated material 2+Electron micrograph of / PEDOT-modified NCM811. Detailed Implementation

[0023] The present invention will be further described in detail below through embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0024] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the reagents, methods and equipment used are conventional reagents, methods and equipment in this technical field.

[0025] For the sake of brevity, this article only discloses some numerical values ​​and the range of options. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range. Similarly, any upper limit can be combined with any other upper limit to form an unspecified range; the options in the range of options can also be combined arbitrarily.

[0026] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art.

[0027] The abbreviation PEDOT used in this application is short for poly(3,4-ethylenedioxythiophene).

[0028] This application provides a cathode material, including a ternary NCM material, wherein the surface of the ternary NCM material is coated with Co. 2+ Conductive polymer materials are used to form modified ternary NCM materials.

[0029] This application also provides a method for preparing a cathode material, which involves mixing and reacting a ternary NCM, a cobalt-containing material, and a conductive polymer to prepare a modified ternary NCM material.

[0030] In some embodiments, the reaction process involves mixing the reactants ternary NCM, cobalt-containing materials, and conductive polymer in water and reacting them at a high temperature of 180°C-200°C for 20-24 hours.

[0031] The conductive polymers used in this application include, but are not limited to, poly(3,4-ethylenedioxythiophene), polyaniline, polypyrrole, and poly(p-styrene).

[0032] In some embodiments, the conductive polymer is poly(3,4-ethylenedioxythiophene), forming Co on the surface of the ternary NCM material. 2+ / PEDOT; The mass ratio of ternary NCM to poly(3,4-ethylenedioxythiophene) ranges from 30 to 34:1.

[0033] The cobalt-containing materials in this application include, but are not limited to: cobalt sulfate, cobalt chloride, cobalt hydroxide, cobalt carbonate, etc.

[0034] In some embodiments, cobalt-containing materials are cobalt sulfate; the mass ratio of ternary NCM to CoSO4·7H2O ranges from 16 to 20:1.

[0035] In some embodiments, a mixture of ternary NCM, cobalt-containing materials, and conductive polymers is reacted at high temperature and then processed, such as by centrifugal washing and vacuum drying, to obtain a modified ternary NCM material product.

[0036] This application provides a positive electrode sheet, which includes a positive electrode active material, including the positive electrode material of this application or the positive electrode material prepared by the method of this application.

[0037] Batteries containing the positive electrode material of this application can be lithium-ion batteries, sodium-ion batteries, etc. Typically, the battery of this application may include a positive electrode, a negative electrode, an electrolyte, and a separator. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrode. The electrolyte acts as a conductor of ions between the positive and negative electrode. This application does not impose any particular limitation on the type of electrolyte and can select one according to requirements; for example, the electrolyte can be liquid, gel, or all-solid. The separator is disposed between the positive and negative electrode and mainly serves to prevent short circuits between the positive and negative electrodes while allowing ions to pass through. This application does not impose any particular limitation on the type of separator and can use any known porous separator with good chemical and mechanical stability. This invention does not specifically limit the positive electrode, negative electrode, electrolyte, and separator of the above-mentioned battery.

[0038] When preparing the positive electrode sheet using the positive electrode material of this application, conventional preparation methods can be used, and binders and conductive agents used in this field can be employed. The ratio of the positive electrode material to the binder and conductive agent can be obtained by those skilled in the art through experiments.

[0039] This application provides a battery, which uses the positive electrode sheet of this application.

[0040] In some embodiments, the battery of this application can be assembled into a battery module, and the number of batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0041] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0042] This application provides an electrical device that uses the battery described in this application.

[0043] In an electrical device containing the battery of this application, the battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but is not limited to these. As an electrical device, the battery can be selected according to its usage requirements.

[0044] The present invention will be further described in detail below with reference to specific embodiments:

[0045] Example 1:

[0046] 1. Preparation of modified NCM811

[0047] NCM811, CoSO4·7H2O, and poly(3,4-ethylenedioxythiophene)PEDOT were dissolved in pure water and stirred until homogeneous. The mixture was then transferred to a reactor and baked at 180℃-200℃ for 20-24 h. After centrifugation, washing, and vacuum drying at 60℃ for 20-24 h, modified NCM811 was obtained. The mass ratio of NCM811 to CoSO4·7H2O was 18:1, and the mass ratio of NCM811 to PEDOT was 32:1. Co was formed on the surface of NCM811. 2+ / PEDOT wrapping.

[0048] 2. Preparation of positive electrode slurry:

[0049] The positive electrode active material is the modified NCM811 obtained in step 1, the binder is PVDF (Wu Yu, KF1100), and the conductive agent is Super P (Swiss Temico). The active material, binder and conductive agent are mixed in a mass ratio of 95.0:2.2:2.8. After being mixed evenly, the mixture is coated on a 13µm aluminum foil and dried in a vacuum drying oven at 120℃ for 12 hours.

[0050] 3. Assembly of button batteries:

[0051] The button cell battery casing uses the CR2032 model, the separator uses a 20um separator, and the electrode uses a uniformly coated positive electrode. In a glove box filled with argon gas, the button cell battery is assembled in the following order: battery casing - placing the positive electrode - adding electrolyte - placing the separator - adding electrolyte - placing the lithium sheet - placing the spacer / spring - battery casing.

[0052] 4. Cyclic performance testing:

[0053] The button cell batteries were subjected to 50 cycles of 0.2C charge-discharge testing using a button cell charge-discharge tester (Wuhan Landian, CT2001A), with a voltage range of 3.0-4.5V. The test results are shown in Table 1.

[0054] 5. Electrode peel strength test:

[0055] Take the positive electrode sheet prepared in step 3, cut a sample with a size of 15cm*5cm, fix it on the steel plate, fix the steel plate and the sample in the sample test area of ​​the peel force tester, set the speed to 200mm / min and the test distance to 200mm, start the equipment, and after the test is completed, read the data. The test results are shown in Table 1.

[0056] Example 2:

[0057] It is basically the same as Example 1, except that the mass ratio of NCM811 to CoSO4.7H2O is 14:1.

[0058] Example 3:

[0059] It is basically the same as Example 1, except that the mass ratio of NCM811 to CoSO4.7H2O is 16:1.

[0060] Example 4:

[0061] It is basically the same as Example 1, except that the mass ratio of NCM811 to CoSO4.7H2O is in the range of 20:1.

[0062] Example 5:

[0063] It is basically the same as Example 1, except that the mass ratio of NCM811 to CoSO4.7H2O is 22:1.

[0064] Example 6:

[0065] It is basically the same as Example 1, except that the mass ratio of NCM811 to PEDOT is 28:1.

[0066] Example 7:

[0067] It is basically the same as Example 1, except that the mass ratio of NCM811 to PEDOT is 30:1.

[0068] Example 8:

[0069] It is basically the same as Example 1, except that the mass ratio of NCM811 to PEDOT is 34:1.

[0070] Example 9:

[0071] It is basically the same as Example 1, except that the mass ratio of NCM811 to PEDOT is 32:1.

[0072] Comparative Example 1:

[0073] It is basically the same as Example 1, except that CoSO4.7H2O is not introduced in step 1.

[0074] Comparative Example 2:

[0075] It is basically the same as Example 1, except that PEDOT is not added in step 1.

[0076] The test evaluation results of each embodiment and comparative example are shown below:

[0077] Table 1. Test results of the examples and comparative examples.

[0078] serial number Cyclic performance Electrode peeling force Example 1 93.8％ 23.8 N / m Example 2 91.1％ 17.9 N / m Example 3 91.5％ 18.5 N / m Example 4 91.4％ 18.2 N / m Example 5 91.4％ 17.6 N / m Example 6 90.5％ 16.5 N / m Example 7 90.8％ 17.8 N / m Example 8 91.4％ 17.4 N / m Example 9 90.1％ 16.3 N / m Comparative Example 1 84.1％ 9.6 N / m Comparative Example 2 81.3％ 8.5 N / m

[0079] The test results show that:

[0080] The cycle performance and electrode peeling force of Example 1 of this invention are superior to those of Examples 2-9, and significantly superior to those of Comparative Examples 1 and 2. This invention has found that by using modified NCM material as the cathode material and introducing Co... 2+ This invention can improve the cycle stability of traditional NCMs. Further research has found that by introducing a conductive polymer, this invention can not only improve the conductivity of the cathode material, but also simultaneously improve the electrode peeling force between the active material and the aluminum foil. Unexpectedly, the combined effect of the conductive polymer and the cobalt-containing material can significantly improve both cycle performance and electrode peeling force, producing a synergistic effect. The process of this solution is simple, but the effect is obvious and it is worth promoting and applying.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A positive electrode material, characterized by: The positive electrode material comprises a ternary NCM material, and the ternary NCM material is coated with Co on the surface 2+ The modified ternary NCM material is formed by mixing the reaction raw materials ternary NCM, Co-containing material and conductive polymer in water and reacting at a high temperature of 180-200 DEG C for 20-24 h, wherein the conductive polymer is poly(3,4-ethylenedioxythiophene).

2. The method of claim 1, wherein: The conductive polymer is at least one of poly(3,4-ethylenedioxythiophene), polyaniline, polypyrrole, and polyparaphenylenevinylene.

3. The method of claim 1, wherein: The mass ratio of the ternary NCM to poly(3,4-ethylenedioxythiophene) is in the range of 30-34:1, and Co 2+ / PEDOT is formed on the surface of the ternary NCM material.

4. The method of claim 1, wherein: The cobalt-containing material is at least one of cobalt sulfate, cobalt chloride, cobalt hydroxide, and cobalt carbonate.

5. The method of claim 1, wherein: The cobalt-containing material is cobalt sulfate, and the mass ratio of the ternary NCM to CoSO4.7H2O ranges from 16 to 20:

1.

6. A positive electrode sheet characterized by comprising: The positive electrode plate comprises a positive electrode active material, and the positive electrode active material comprises the positive electrode material of claim 1 or the positive electrode material prepared by the method of any one of claims 2-5.

7. A battery, characterized by: The battery comprises the positive electrode plate of claim 6.

8. An electrical device, characterized by: The electrical device comprises the battery of claim 7.

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