Negative electrode material for improving cycle performance of lithium battery, preparation method of negative electrode material, negative electrode plate and battery

Abstract

The invention discloses a negative electrode material for improving the cycle performance of a lithium battery, a preparation method of the negative electrode material, a negative electrode plate and a battery, and the preparation method comprises the following steps: S1, growing SnO2 on a carbon nanotube through a hydrothermal synthesis method to form a one-dimensional composite material SnO2 (at) CNT; s2, Zr ions and a silane coupling agent are introduced into the one-dimensional composite material SnO2 (at) CNT, and the modified SnO2 (at) CNT material is obtained. According to the invention, the cycle life of the lithium battery using the stannic oxide negative electrode material is prolonged through material composite modification.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a negative electrode material for improving the cycle performance of a lithium battery, a preparation method thereof, a negative electrode sheet and a battery. Background Art

[0002] With the increasing popularity of new energy vehicles and the iterative upgrades of energy storage technologies, the market has placed more stringent requirements on the performance of lithium battery anode materials, requiring them to not only meet the needs of large-capacity energy storage but also withstand the test of long-term charge and discharge. Tin dioxide, a naturally abundant metal oxide, has attracted considerable attention in the anode material field due to its outstanding energy storage potential. This material exhibits significant advantages in storing large amounts of electrical energy during the repeated insertion and extraction of lithium ions.

[0003] However, in practical applications, the volume of tin dioxide is prone to drastic changes during the charging and discharging process, causing the electrode to pulverize, thereby affecting the cycle performance of the battery. Therefore, how to modify it to improve the cycle life of the battery has become the research focus of tin dioxide negative electrode materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a negative electrode material and a preparation method thereof, a negative electrode sheet and a battery for improving the cycle performance of a lithium battery, so as to solve the above problems.

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

[0006] The present invention is achieved through the following technical solutions:

[0007] The first aspect of the present application provides a method for preparing a negative electrode material for improving the cycle performance of a lithium battery, comprising the following steps:

[0008] S1: SnO2 is grown on carbon nanotubes by hydrothermal synthesis to form a one-dimensional composite material SnO2@CNT;

[0009] S2: Zr ions and silane coupling agent are introduced into the one-dimensional composite material SnO2@CNT to obtain modified SnO2@CNT material.

[0010] In step S1, the growth of SnO2 on carbon nanotubes by hydrothermal synthesis is specifically as follows: mixing a Sn-containing compound and carbon nanotube material in water, and baking at 130-150°C for 8-12 hours.

[0011] To optimize the above technical solutions, specific measures taken also include:

[0012] The mass ratio of Sn element to carbon nanotube material in the Sn-containing compound is 4 to 7:1.

[0013] In step S2, Zr ions and silane coupling agent are introduced into the one-dimensional composite material SnO2@CNT by high-temperature calcination.

[0014] Step S2 specifically comprises grinding and mixing the Zr-containing compound, the silane coupling agent and the one-dimensional composite material SnO2@CNT together, and calcining them at 460-550°C for 10-15 hours under an inert protective atmosphere to obtain a modified SnO2@CNT material; wherein the calcination heating rate is 15-25°C / min, and the annealing rate is 25-35°C / min.

[0015] Furthermore, the silane coupling agent is selected from at least one of γ-mercaptopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, aminopropyltriethoxysilane, epoxypropyltrimethoxysilane and methyltrimethoxysilane.

[0016] Furthermore, the mass ratio of the one-dimensional composite material SnO2@CNT to the Zr element in the Zr-containing compound is 87-108:1; the mass ratio of the one-dimensional composite material SnO2@CNT to the silane coupling agent is 95-110:1.

[0017] The second aspect of the present application provides a negative electrode material prepared using the above method.

[0018] The third aspect of the present application provides a negative electrode sheet comprising the above-mentioned negative electrode material.

[0019] A fourth aspect of the present application provides a battery comprising the above-mentioned electrode.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention firstly adopts a hydrothermal synthesis method to prepare SnO2@CNT material, grows SnO2 on CNT (carbon nanotube) material to form a one-dimensional composite material SnO2@CNT material. The introduction of CNT material not only improves the conductivity of the negative electrode material SnO2, but also the special one-dimensional composite structure can inhibit the lateral expansion of SnO2 material during the charge and discharge process, reducing capacity loss; then, Zr is introduced by high-temperature calcination. 4+ After the silane coupling agent, Zr 4+ Replacing some Sn sites can reduce the volume change of the reduction product Sn and show better cycle performance; at the same time, the introduction of silane coupling agent modifies the SnO2@CNT surface, acting as a bridge, making the negative electrode material and the conductive agent in the negative electrode slurry more closely combined, inhibiting the expansion of SnO2, thereby further improving the battery cycle performance.

[0022] The battery prepared by the solution of the present invention has excellent performance in 20-cycle, 50-cycle and 100-cycle cycle performance, and the cycle life of the lithium battery using tin dioxide (SnO2) negative electrode materials is improved through material modification. DETAILED DESCRIPTION

[0023] The above contents of the present invention are further described in detail below in the form of specific implementation methods, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0024] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the reagents, methods and equipment used are conventional reagents, methods and equipment in the art unless otherwise specified.

[0025] For the sake of simplicity, this document only specifically discloses some numerical values ​​and optional ranges. 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 optional items in the optional range can also be combined arbitrarily.

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

[0027] The present invention provides a method for preparing a negative electrode material for improving the cycle performance of a lithium battery, comprising the following steps:

[0028] S1: SnO2 is grown on carbon nanotubes using a hydrothermal synthesis method to form a one-dimensional composite material SnO2@CNT;

[0029] S2: Zr ions and silane coupling agent are introduced into the one-dimensional composite material SnO2@CNT to obtain modified SnO2@CNT material.

[0030] In step S1, SnO2 is grown on the carbon nanotubes by a hydrothermal synthesis method. Specifically, a Sn-containing compound and a carbon nanotube material are mixed in water and baked at 130-150°C for 8-12 hours.

[0031] The mass ratio of Sn element to carbon nanotube material in the Sn-containing compound is 4 to 7:1.

[0032] In step S2, Zr ions and a silane coupling agent are simultaneously introduced into the one-dimensional composite material SnO2@CNT by high-temperature calcination.

[0033] Step S2 specifically comprises grinding and mixing the Zr-containing compound, the silane coupling agent and the one-dimensional composite material SnO2@CNT together, and calcining them at 460-550°C for 10-15 hours under an inert protective atmosphere to obtain a modified SnO2@CNT material; wherein the calcination heating rate is 15-25°C / min, and the annealing rate is 25-35°C / min.

[0034] In some embodiments, the silane coupling agent is selected from at least one of γ-mercaptopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, aminopropyltriethoxysilane, epoxypropyltrimethoxysilane, or methyltrimethoxysilane.

[0035] In some embodiments, the mass ratio of the one-dimensional composite material SnO2@CNT to the Zr element in the Zr-containing compound is 87-108:1; the mass ratio of the one-dimensional composite material SnO2@CNT to the silane coupling agent is 95-110:1.

[0036] The present invention also provides a negative electrode material prepared by the above method.

[0037] The introduction of CNT (carbon nanotube) material in this application not only improves the conductivity of the negative electrode material SnO2, but also the special one-dimensional composite structure can inhibit the lateral expansion of the SnO2 material during the charge and discharge process, reducing capacity loss. 4+ After the silane coupling agent, Zr 4+ Replacing some Sn sites can reduce the volume change of the reduction product Sn and show better cycle performance; at the same time, the introduction of silane coupling agent modifies the SnO2@CNT surface, acting as a bridge, making the negative electrode material and the conductive agent in the negative electrode slurry more closely combined, inhibiting the expansion of SnO2, thereby further improving the battery cycle performance.

[0038] Specifically, CNT, as a highly conductive substrate, not only provides a fast electron transmission channel for SnO2, but also limits the lateral expansion of SnO2 during the charge and discharge process through its one-dimensional structure. This physical constraint can reduce the particle breakage and electrode structure collapse caused by volume change of the active material, thereby reducing capacity decay. 4+ After replacing Sn sites, the larger ionic radius allows for a more stable crystal structure. This doping modulates the SnO2 lattice parameters, inhibiting Sn particle aggregation and volume changes during lithiation / delithiation, while also improving the material's structural stability. The chemical bonds and coupling interactions formed by the silane coupling agent create a bridging effect, strengthening the bond between the active material and the conductive network, creating a more stable conductive pathway. Furthermore, the surface coating prevents SnO2 volume expansion from damaging the electrode structure.

[0039] The present invention also provides a negative electrode sheet comprising the above-mentioned negative electrode material.

[0040] The materials on the negative electrode sheet of the present invention also include a conductive agent and a binder, wherein the ratio of the negative electrode material, the conductive agent and the binder can be obtained by those skilled in the art based on experience and experimental procedures.

[0041] The present invention also provides a battery comprising the above-mentioned electrode piece.

[0042] The technical solution of the present invention is further described in detail below with reference to specific embodiments:

[0043] Example 1:

[0044] (1) Preparation of modified SnO2@CNT materials

[0045] After uniformly mixing SnCl4·5H2O and a small amount of CNT material in deionized water, the mixture was placed in a forced air drying oven and baked at 140℃ for 10h. The SnO2@CNT material was obtained by filtering, washing and drying. l4 The mass ratio of 5H2O to CNT material is 16:1;

[0046] Next, the SnO2@CNT material, a small amount of ZrO2 and γ-mercaptopropyltriethoxysilane were mechanically ball-milled, placed in a tubular furnace, introduced N2, and calcined at 500°C for 12 hours to obtain modified SnO2 material; wherein, the heating rate was 20°C / min, and the annealing rate was 30°C / min; the mass ratio of SnO2@CNT material to ZrO2 was 70~75:1, and the mass ratio of SnO2@CNT material to γ-mercaptopropyltriethoxysilane was 100~105:1.

[0047] (2) Preparation of negative electrode slurry:

[0048] The negative electrode active material is the modified SnO2@CNT material obtained in step (1), the binder is sodium alginate, and the conductive agent is acetylene black; they are all stirred and mixed in a ratio of active material: binder: conductive agent = 7:1:2, and after mixing evenly, coated on a 10um copper foil and dried in a vacuum drying oven at 70°C for 20 minutes.

[0049] (3) Assembly of button half-cell:

[0050] The button battery shell uses CR2032 model, the diaphragm uses 20um diaphragm, and the electrode uses a negative electrode with a uniform coating. In a glove box filled with argon, the button battery is assembled in the following order: battery shell ~ place the negative electrode ~ drip electrolyte ~ place the diaphragm ~ drip electrolyte ~ place the lithium sheet ~ place the gasket spring ~ battery shell.

[0051] (4) Cyclic performance test:

[0052] A button battery charge and discharge tester (Wuhan Blue Electric, CT2001A) was used to perform 20, 50, and 100 cycles of 0.2C charge and discharge tests on the button battery with a voltage range of 0.01 to 2.5 V. The test results are shown in Table 1.

[0053] Example 2:

[0054] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the mass ratio of SnO2@CNT material to ZrO2 is 60-65:1.

[0055] Example 3:

[0056] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the mass ratio of SnO2@CNT material to ZrO2 is 65-70:1.

[0057] Example 4:

[0058] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the mass ratio of SnO2@CNT material to ZrO2 is 75-80:1.

[0059] Example 5:

[0060] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the mass ratio of SnO2@CNT material to ZrO2 is 80-85:1.

[0061] Example 6:

[0062] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the mass ratio of SnO2@CNT material to γ-mercaptopropyltriethoxysilane is 90-95:1.

[0063] Example 7:

[0064] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the mass ratio of SnO2@CNT material to γ-mercaptopropyltriethoxysilane is 95-100:1.

[0065] Example 8:

[0066] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the mass ratio of SnO2@CNT material to γ-mercaptopropyltriethoxysilane is 105-110:1.

[0067] Example 9:

[0068] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the mass ratio of SnO2@CNT material to γ-mercaptopropyltriethoxysilane is 110-115:1.

[0069] Example 10:

[0070] The scheme of this embodiment is basically the same as that of Example 1, with the only difference being that the silane coupling agent in this embodiment adopts epoxypropyltrimethoxysilane, and the mass ratio thereof is consistent with that in Example 1.

[0071] Comparative Example 1:

[0072] The difference between this comparative example and Example 1 is that no CNT material is introduced in step 1, and the rest is the same as Example 1.

[0073] Comparative Example 2:

[0074] The difference between this comparative example and Example 1 is that no ZrO2 material is introduced in step 1, and the rest is the same as Example 1.

[0075] Comparative Example 3:

[0076] The difference between this comparative example and Example 1 is that no γ-mercaptopropyltriethoxysilane material is introduced in step 1, and the rest is the same as Example 1.

[0077] Comparative Example 4:

[0078] The difference between this comparative example and Example 1 is that traditional SnO2 material is used as the negative electrode material, and the rest is the same as Example 1.

[0079] The test evaluation results of each embodiment are shown below. It should be noted that the above embodiments and comparative examples were tested multiple times under the above conditions. The data in Table 1 are the average values ​​of multiple tests for each example:

[0080] Table 1

[0081] serial number 20-cycle performance 50-cycle performance 100-cycle performance Example 1 90.1％ 87.1％ 83.6％ Example 2 87.3％ 83.3％ 78.3％ Example 3 87.5％ 84.8％ 80.9％ Example 4 87.6％ 85.2％ 81.6％ Example 5 87.1％ 83.1％ 78.1％ Example 6 83.5％ 79.2％ 73.3％ Example 7 86.3％ 83.8％ 77.9％ Example 8 86.8％ 84.2％ 78.1％ Example 9 83.3％ 78.9％ 73.1％ Example 10 89.5％ 86.1％ 82.2％ Comparative Example 1 69.2％ 60.1％ 47.8％ Comparative Example 2 71.2％ 62.5％ 48.5％ Comparative Example 3 70.1％ 61.8％ 48.0％ Comparative Example 4 65.3％ 51.7％ 32.2％

[0082] By comparing Example 1 with Examples 2 to 9, it was found that the ratio of Zr ions and silane coupling agent introduced into SnO2@CNT had an impact on the cycle performance of the modified product, and had a better effect within the range of Example 1 and Examples 3, 4, 7, and 8, corresponding to a mass ratio of SnO2@CNT material to Zr element in the Zr-containing compound of approximately 87 to 108:1, and a mass ratio to the silane coupling agent of 95 to 110:1.

[0083] Comparing Example 1 with Comparative Examples 1 to 3, it is found that the synergistic effects of carbon nanotubes, Zr ions and silane coupling agents are indispensable. If any one of these materials is missing, the technical effect of the present invention cannot be achieved.

[0084] By comparing Example 1 with Comparative Example 4, it is found that the battery prepared by the scheme of the present invention has excellent performance in 20 cycles, 50 cycles and 100 cycles. The present invention improves the cycle life of lithium batteries using tin dioxide (SnO2) negative electrode materials through material modification.

[0085] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent replacement and improvement made by any technician familiar with the profession to the above embodiment without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a negative electrode material for improving the cycle performance of a lithium battery, characterized in that: The following steps are involved: S1: SnO2 is grown on carbon nanotubes by hydrothermal synthesis to form a one-dimensional composite material SnO2@CNT; S2: Zr ions and silane coupling agent are introduced into the one-dimensional composite material SnO2@CNT to obtain modified SnO2@CNT material.

2. The method for preparing a negative electrode material for improving the cycle performance of a lithium battery according to claim 1, wherein: In step S1, the growth of SnO2 on carbon nanotubes by hydrothermal synthesis is specifically as follows: mixing a Sn-containing compound and carbon nanotube material in water, and baking at 130-150°C for 8-12 hours.

3. The method for preparing a negative electrode material for improving the cycle performance of a lithium battery according to claim 2, wherein: The mass ratio of Sn element to carbon nanotube material in the Sn-containing compound is 4 to 7:

1.

4. The method for preparing a negative electrode material for improving the cycle performance of a lithium battery according to claim 1, wherein: In step S2, Zr ions and silane coupling agent are introduced into the one-dimensional composite material SnO2@CNT by high-temperature calcination.

5. The method for preparing a negative electrode material for improving the cycle performance of a lithium battery according to claim 4, characterized in that: Step S2 specifically comprises grinding and mixing the Zr-containing compound, the silane coupling agent and the one-dimensional composite material SnO2@CNT together, and calcining them at 460-550°C for 10-15 hours under an inert protective atmosphere to obtain a modified SnO2@CNT material; wherein the calcination heating rate is 15-25°C / min, and the annealing rate is 25-35°C / min.

6. The method for preparing a negative electrode material for improving the cycle performance of a lithium battery according to claim 5, characterized in that: The silane coupling agent is selected from at least one of γ-mercaptopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, aminopropyltriethoxysilane, epoxypropyltrimethoxysilane and methyltrimethoxysilane.

7. The method for preparing a negative electrode material for improving the cycle performance of a lithium battery according to claim 6, characterized in that: The mass ratio of the one-dimensional composite material SnO2@CNT to the Zr element in the Zr-containing compound is 87-108:1; the mass ratio of the one-dimensional composite material SnO2@CNT to the silane coupling agent is 95-110:

1.

8. A negative electrode material, characterized in that: The method according to any one of claims 1 to 7 is used for preparation.

9. A negative electrode sheet, characterized in that: Contains the negative electrode material according to claim 8.

10. A battery, characterized in that: Comprising the pole piece according to claim 9.