SiOx-based negative electrode material and preparation method thereof, negative electrode plate and lithium ion battery

Abstract

The invention provides a SiOx-based negative electrode material and a preparation method thereof, a negative electrode plate and a lithium ion battery. The method comprises the following steps: uniformly mixing silicon powder, transition metal oxide powder and tin powder to form mixed powder; adding the mixed powder into a ball mill, and carrying out ball milling under the protection of an inert atmosphere to obtain SiOx-based powder; and placing the SiOx-based powder in a heating furnace, carrying out heat preservation at a preset temperature, and crushing the obtained powder after discharging to obtain the SiOx-based negative electrode material. The homogeneous-phase SiOx-based negative electrode material is prepared under the conditions of room-temperature sintering and low-temperature sintering, and the cycling stability and the rate capability of the material can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and specifically, to a SiO x -based anode material, a preparation method thereof, an anode electrode sheet, and a lithium-ion battery. Background Art

[0002] SiO x materials are an important type of anode materials for lithium-ion batteries. The theoretical capacity changes with the atomic ratio x of Si to O, and can be up to nearly 3750 mAh g of Si at most. -1 However, the higher the Si content in the SiO x material, the more serious volume expansion will occur during lithium storage, resulting in pulverization of the anode material and battery failure. In addition, the SiO x material has poor electrical conductivity, leading to a decline in the rate performance of the anode material.

[0003] Currently, the industrial method for producing SiO x materials is chemical vapor deposition of Si and SiO 2 in a high-temperature vacuum environment at 1400°C. This method has extremely high energy consumption and requires a strict vacuum environment to control the oxygen content in the preparation atmosphere.

[0004] After retrieval, the patent with the application number 202210959559 discloses a metal-doped silicon oxide anode material, which uses a porous ceramic as a skeleton, and silicon monoxide and doping elements are uniformly and dispersedly distributed in the pores of the porous ceramic by a liquid phase method or a solid phase method. The patent with the application number 202110865725 discloses a metal-doped SiO x anode material. Si, SiO 2 and a reducing metal are mixed in proportion and put into a material crushing device, and crushing and mixing are carried out under an inert atmosphere condition, so that the three material phases of Si, SiO 2 and the reducing metal are broken to a certain extent; a conductive agent is added in proportion, and crushing and mixing are continued under an inert atmosphere condition; a solid-phase coating material is added, and a coating structure material is formed by a solid-phase coating granulation method; the coating structure material is put into a heat treatment device and sintered under an inert atmosphere condition to carry out a reduction treatment on the coating material, forming a mixed crystal phase material with a phase structure in which three crystal phases of Si, SiO 2 and the silicate of the reducing metal coexist and the conductive agent is uniformly dispersed. The methods for preparing the metal-doped silicon oxide anode materials disclosed in the above patents are all methods for preparing multi-phase mixtures and cannot prepare a homogeneous-phase material.

[0005] The Chinese invention patent with application publication number CN116864637A discloses a low-entropy antimony-based binary ultrafine nanocrystalline oxide negative electrode material and preparation method. The preparation method is ball milling and mixing plus cooling and sintering. Antimony and impurity metal salts are first ball milled and mixed, and then the mixed salt is annealed in a muffle furnace, raised to 350-600℃ at 5-10℃ / s, that is, cooled to 200℃ at a rate of 0.05-10℃ / s and then cooled to room temperature with the furnace. The role of ball milling in this patent is to make the raw materials mix evenly, and the reaction mainly occurs during the sintering process, which requires high temperature control of the sintering reaction.

[0006] The Chinese invention patent with application publication number CN113506861A discloses a lithium-ion battery silicon-based composite negative electrode material and its preparation method. The patent is aimed at antimony-based materials, and silicon and doped metals are dispersed in the substrate formed by silicon oxide, and no homogeneous structure is formed. SUMMARY OF THE INVENTION

[0007] Aiming at the defects in the prior art, the purpose of the present invention is to provide a SiO x Based negative electrode material and preparation method, negative electrode plate and lithium ion battery, can prepare SiO with controllable Si and O ratio at room temperature x Materials, and the introduction of transition metals and Sn into the SiO system to improve the material's cycle stability and rate performance.

[0008] According to a first aspect of the present invention, a SiO x A method for preparing a negative electrode material, the method comprising:

[0009] Mix silicon powder, transition metal oxide powder and tin powder evenly to form mixed powder;

[0010] Add the mixed powder into a ball mill and perform ball milling under the protection of an inert atmosphere to obtain SiOx-based powder;

[0011] Put the SiOx-based powder in a heating furnace and keep it warm at a preset temperature, and crush the obtained powder after discharging to obtain a SiOx-based negative electrode material.

[0012] Optionally, the silicon powder, transition metal oxide powder and tin powder are uniformly mixed to form a mixed powder, wherein: the transition metal oxide powder is Fe 2 O 3 Powder, Fe 3 O 4 Powder, CoO powder, Co 2 O 3 Any one or more of powder, MnO powder and CuO powder.

[0013] Optionally, the silicon powder, transition metal oxide powder, and tin powder are mixed evenly to form a mixed powder, where: the silicon powder accounts for 15-51% of the total mass of the mixed powder, and the atomic mass ratio of the tin powder to the transition metal in the transition metal oxide powder is less than 2:1.

[0014] Preferably, the silicon powder, transition metal oxide powder, and tin powder are mixed evenly to form a mixed powder, where: the silicon powder accounts for 25-40% of the total mass of the mixed powder.

[0015] Optionally, the mixed powder is added to a ball mill and ball milled under an inert atmosphere, including: using a swing vibration ball mill, with a ball-to-material ratio of 25:1 to 50:1 during the ball milling process, a vibration frequency of the ball mill of 800-1400 rpm, and a ball milling time of 2-16 h.

[0016] Optionally, the mixed powder is added to a ball mill and ball milled under an inert atmosphere, including: using a planetary ball mill, with a ball-to-material ratio of 25:1 to 50:1 during the ball milling process, a vibration frequency of the ball mill of 300-500 rpm, and a ball milling time of 10-50 h.

[0017] Optionally, the SiOx-based powder is placed in a heating furnace and kept at a preset temperature, where: the heating furnace is a box-type heating furnace or a tube-type heating furnace, the preset temperature is 300-600 °C, and it is kept for 2-5 hours, and an inert protective gas is introduced during the heat preservation process.

[0018] According to the second aspect of the present invention, there is provided a SiO x -based anode material, and the SiO x -based anode material is prepared by using the above method.

[0019] According to the third aspect of the present invention, there is provided a negative electrode sheet, and the negative electrode sheet includes a carbon coating layer and the above-mentioned SiO x -based anode material, and the carbon coating layer covers the surface of the SiO x -based anode material.

[0020] According to the fourth aspect of the present invention, there is provided a lithium-ion battery, and the lithium-ion battery includes the above-mentioned SiO x -based anode material, or the above-mentioned negative electrode sheet.

[0021] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0022] 1. The present invention adopts a ball milling method that can be operated at room temperature and subsequent low-temperature heat treatment, and obtains a homogeneous-phase SiO x -based anode material through the reaction of Si, transition metal oxide, and tin during the ball milling process, and prepares SiO under the conditions of room temperature and low-temperature sintering.x The base negative electrode material does not require too high a temperature, thus reducing energy consumption.

[0023] 2. The present invention can control the atomic ratio of Si to O in SiO generated according to the feeding of silicon powder and transition metal oxide in the raw materials, and simultaneously conduct metal element doping to obtain a homogeneous material. The negative electrode material of the present invention has high cycle stability and excellent rate performance. x The negative electrode material of the present invention has high cycle stability and excellent rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects, and advantages of the present invention will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0025] Figure 1 It is a schematic flow chart of the SiO-based negative electrode material and its preparation method in the embodiment of the present invention; x It is a schematic flow chart of the SiO-based negative electrode material and its preparation method in the embodiment of the present invention;

[0026] Figure 2 It is a schematic structural diagram of the SiO-based negative electrode material with homogeneous element doping in the embodiment of the present invention; x It is a schematic structural diagram of the SiO-based negative electrode material with homogeneous element doping in the embodiment of the present invention;

[0027] Figure 3 It is a schematic structural diagram of the SiO-based negative electrode material with mixed crystal phases and element doping in the embodiment of the present invention;

[0028] Figure 4 It is an X-ray diffraction pattern of the SiO-based negative electrode material in Example 1 of the present invention;

[0029] Figure 5 It is an X-ray diffraction pattern of the SiO-based negative electrode material in Example 2 of the present invention; 0.5 It is an X-ray diffraction pattern of the SiO-based negative electrode material in Example 2 of the present invention;

[0030] Figure 6 It is an X-ray diffraction pattern of the SiO-based negative electrode material in Example 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0032] The embodiment of the present invention provides a preparation method of a SiO-based negative electrode material. Referring to x , the method includes: Figure 1 , the method includes:

[0033] Step S1: Mix silicon powder, transition metal oxide (TMO) powder, and tin powder evenly to form a mixed powder;

[0034] Step S2: Add the mixed powder into a ball mill and ball mill it under the protection of an inert atmosphere to obtain SiOx-based powder;

[0035] Step S3: Place the SiOx-based powder in a heating furnace and keep it at a preset temperature. After discharging, crush the obtained powder to obtain the SiOx-based anode material.

[0036] In some embodiments, in Step S1, the transition metal oxide powder is any one or several of Fe 2 O 3 powder, Fe 3 O 4 powder, CoO powder, Co 2 O 3 powder, MnO powder, and CuO powder. It should be noted that to meet the requirements for transition metals in the anode material, other types of transition metal oxide powders can also be used.

[0037] In some embodiments, in Step S1, the silicon powder accounts for 15 - 51% of the total mass of the mixed powder, and the range of x in the obtained SiO x is 0.3 - 1.7. The atomic mass ratio of tin powder to the transition metal in the transition metal oxide powder is less than 2:1.

[0038] Preferably, the silicon powder accounts for 25 - 40% of the total mass of the mixed powder, and the range of x in the obtained SiO x is 0.58 - 1.14.

[0039] In some embodiments, in Step S2, swing vibration ball milling is adopted, that is, ball milling is carried out using a swing vibration ball mill. During the ball milling process, the ball-to-material ratio, that is, the mass ratio of the grinding balls to the raw materials, is 25:1 - 50:1, the vibration frequency of the ball mill is 800 - 1400 rpm, and the ball milling time is 2 - 16 h.

[0040] In some alternative embodiments, in Step S2, planetary ball milling is adopted, that is, ball milling is carried out using a planetary ball mill. During the ball milling process, the ball-to-material ratio is 25:1 - 50:1, the vibration frequency of the ball mill is 300 - 500 rpm, and the ball milling time is 10 - 50 h.

[0041] In the embodiments of the present invention, the input energy of the ball milling is controlled by adjusting the ball milling parameters, so as to obtain a homogeneous-phase SiOx-based powder. It should be noted that in some other embodiments, other types of high-energy ball milling methods can also be adopted to realize the reaction during the ball milling process to obtain a homogeneous-phase SiOx-based powder.

[0042] In the above embodiments of the present invention, based on the reactive ball milling method, most of the reactions occur during the ball milling process, and the reaction formula of the ball milling reaction is as follows:

[0043] Si + TM y O x + zSn = SiO x TM y Sn z

[0044] Si + TMO x + Sn = SiO x TM y Sn z + TM 1-y Sn 1-z

[0045] Among them, TM is a transition metal, including one or more of Fe, Mn, Co, and Cu, etc. The values of y and z are obtained from the above reaction equation according to the value of x. Specifically, the range of x is 0.3 - 1.7, the range of y is 0.1 - 0.57, and the range of z is 0.1 - 0.52.

[0046] After the ball milling reaction, in order to make the reaction proceed more fully, the SiOx-based powder is subjected to low-temperature sintering. In some embodiments, in step S3, the heating furnace is a box-type heating furnace or a tube-type heating furnace, and the preset temperature is 300 - 600 °C. This temperature is conducive to the complete progress of the reaction, and at the same time, no phase precipitation will occur, and the nanocrystals and amorphous will not recrystallize; keep warm for 2 - 5 hours, and introduce inert protective gases such as argon and nitrogen during the heat preservation process to prevent oxidation. Thus, the reaction can proceed completely to obtain a powder with a uniform phase distribution.

[0047] The embodiments of the present invention are based on the reactive ball milling method to prepare a metal-doped SiOx negative electrode material. Most of the reactions occur during the ball milling process. Si, Sn, and transition metal oxides are ball milled in an inert atmosphere, and sintering is carried out after ball milling to make the reaction complete. The embodiments of the present invention can generate a homogeneous element-doped SiOx-based negative electrode material and a microstructure in which a metal alloy phase is combined with the element-doped SiOx only under the conditions of room temperature and low-temperature sintering. The embodiments of the present invention improve the conductivity of the SiO x material and the homogeneous metal-doped SiO x composite material with the metal alloy phase to improve the conductivity of the SiO x -based negative electrode, and realize the conductivity regulation of Sn and transition metal doping on SiO x .

[0048] Based on the same inventive concept, the embodiments of the present invention provide a SiO x -based negative electrode material, and this SiOx The base anode material is prepared by using the above method. The anode material includes SiO x material and a doped metal element. The doped elements include Sn and any one or more of transition metals such as Fe, Mn, Co, and Cu. In the SiO x material, the range of x is 0.3 - 1.7. The SiO x base anode material has a microstructure in which SiO doped with metal elements x or SiO doped with metal elements x and a metal alloy phase are dispersedly distributed, as shown in Figure 2 and Figure 3 shown.

[0049] Based on the same inventive concept, an embodiment of the present invention provides a negative electrode plate, which includes a carbon coating layer and the above-mentioned SiO x base anode material, as shown in Figure 2 and Figure 3 shown. The carbon coating layer covers the surface of the SiO x base anode material.

[0050] In the embodiment of the present invention, the method for carbon coating the SiO x base anode material includes any one of gas-phase coating, liquid-phase coating, and solid-phase coating. The mass of the carbon coating accounts for 0 - 20% of the total mass of the SiO x base anode material. Thus, the volume expansion of SiO x can be effectively alleviated, side reactions can be inhibited, and at the same time, the cycle life and stability of the negative electrode plate can be improved.

[0051] Based on the same inventive concept, an embodiment of the present invention further provides a lithium-ion battery, which includes the above-mentioned SiO x base anode material or the above-mentioned negative electrode plate.

[0052] In the above embodiment of the present invention, the ball milling method operable at room temperature and subsequent low-temperature heat treatment are adopted. A homogeneous-phase SiO x base anode material is obtained through the reaction of Si with transition metal oxides and tin during the ball milling process. The SiO x base anode material is prepared under the conditions of room temperature and low-temperature sintering, without the need for too high a temperature, thereby reducing energy consumption. In the above embodiment of the present invention, the atomic ratio of Si to O in the generated SiO x can be controlled according to the feeding of raw materials, and at the same time, metal element doping is carried out to obtain a homogeneous-phase material. The obtained anode material has high cycle stability and excellent rate performance.

[0053] The technical solutions of the present application will be further described in more specific embodiments below.

[0054] Example 1

[0055] This example provides a preparation process and performance test of an iron- and tin-doped SiO-based anode material. The specific preparation process is as follows:

[0056] 30 g of silicon powder, 21 g of tin powder, and 57 g of iron oxide powder were evenly mixed, placed in a ball mill, and under an argon atmosphere, the rotation speed was set at 500 r / min, with forward and reverse rotation, and ball milled for 50 hours to obtain an iron- and tin-doped SiO-based anode material.

[0057] The X-ray diffraction pattern of the SiO-based anode material is as Figure 4 shown, Figure 4 There are two relatively strong diffraction peaks, and at the same time, the diffraction peaks are not sharp, indicating that the structure of the SiO-based anode material is amorphous and the crystallinity is low.

[0058] Example 2

[0059] This example provides a preparation process and performance test of an iron- and tin-doped SiO 0.5 anode material. The specific preparation process is as follows:

[0060] 30 g of silicon powder, 11 g of tin powder, and 29 g of iron oxide powder were evenly mixed, placed in a ball mill, and under an argon atmosphere, the rotation speed was set at 500 r / min, with forward and reverse rotation, and ball milled for 50 hours to obtain an iron- and tin-doped SiO 0.5 anode material.

[0061] SiO 0.5 The X-ray diffraction pattern of the anode material is as Figure 5 shown, Figure 5 In addition to the SiO amorphous envelope, there are characteristic peaks of silicon, proving the 0.5 formation of SiO.

[0062] Example 3

[0063] This example provides a preparation process and performance test of an anode material in which iron- and tin-doped SiO coexists with Sn 2 Fe alloy phase. The specific preparation process is as follows:

[0064] 30 g of silicon powder, 80 g of tin powder, and 57 g of iron oxide powder were evenly mixed, placed in a ball mill, and under an argon atmosphere, the rotation speed was set at 500 r / min, with forward and reverse rotation, and ball milled for 50 hours to obtain a composite material in which iron- and tin-doped SiO coexists with Sn 2 Fe alloy phase.

[0065] In this example, the X-ray diffraction pattern of the SiO-based anode material is as Figure 6 shown, Figure 6In addition to the SiO amorphous envelope, there is also Sn 2 Characteristic peaks of the Fe alloy phase.

[0066] Example 4

[0067] This example provides a preparation process and performance test of a copper- and tin-doped SiO negative electrode material. The specific preparation process is as follows:

[0068] 30 g of silicon powder, 68 g of tin powder, and 85 g of copper oxide powder are uniformly mixed and placed in a ball mill. In an argon atmosphere, the rotation speed is set to 500 r / min, with forward and reverse rotation, and ball milling is carried out for 50 hours to obtain a copper- and tin-doped SiO composite material.

[0069] Example 5

[0070] This example provides a preparation process and performance test of a cobalt- and tin-doped SiO negative electrode material. The specific preparation process is as follows:

[0071] 30 g of silicon powder, 47 g of tin powder, and 59 g of cobalt oxide powder are uniformly mixed and placed in a ball mill. In an argon atmosphere, the rotation speed is set to 500 r / min, with forward and reverse rotation, and ball milling is carried out for 50 hours to obtain a cobalt- and tin-doped SiO composite material.

[0072] The obtained cobalt- and tin-doped SiO composite material is placed in a tubular furnace and kept at 500 °C for 2 h under argon atmosphere protection to obtain the final cobalt- and tin-doped SiO composite material.

[0073] Example 6

[0074] This example provides a preparation process and performance test of a copper-, iron- and tin-doped SiO-based negative electrode material. The specific preparation process is as follows:

[0075] 30 g of silicon powder, 15 g of tin powder, 14 g of iron oxide, and 7 g of copper oxide powder are uniformly mixed and placed in a ball mill. In an argon atmosphere, the rotation speed is set to 500 r / min, with forward and reverse rotation, and ball milling is carried out for 50 hours to obtain an iron- and tin-doped SiO composite material.

[0076] The SiO composite materials prepared in the above examples are used as negative electrode materials, and button-type half-cells and full-cells are assembled for testing. Taking Example 1 as an example, the specific process is as follows:

[0077] The iron- and tin-doped SiO composite material prepared in Example 1 is used as the negative electrode material, and button-type half-cells and full-cells are assembled for testing.

[0078] Preparation and testing of coin-type half-cells: The Fe- and Sn-doped SiO composite material, the conductive additive carbon black, and the binder sodium carboxymethyl cellulose were weighed according to a mass ratio of 95:2:3, followed by slurry mixing, coating, drying, and sheet cutting. Then, coin-type half-cells were assembled in a glove box. A constant current charge-discharge test was performed using a charge-discharge instrument. The cut-off voltage for discharge was 0.01 V, and the cut-off voltage for charge was 1.5 V.

[0079] Preparation method and testing of full cells, including:

[0080] Preparation of the negative electrode material: The Fe- and Sn-doped SiO composite material and graphite were configured into a composite with a specific capacity of 450 mAh / g. The conductive additive and the binder were weighed and mixed in a ratio of 95:2:3, followed by slurry mixing, coating, drying, and sheet cutting.

[0081] Testing: A constant current charge-discharge mode test was performed using a charge-discharge instrument. The cyclic test results of the lithium battery at a current density of 0.1 C showed that the cut-off voltage for discharge was 2.75 V, and the cut-off voltage for charge was 4.2 V. The discharge tests after the first week were all carried out at a current density of 0.1 C. The test results are shown in Table 1 below.

[0082] The method of using the SiO composite material prepared in other examples as the negative electrode material and assembling coin-type half-cells and full cells for testing was the same as that in Example 1. Pure SiO was used as the comparative example. The specific test results are shown in Table 1.

[0083] Table 1 Cyclic test results of lithium batteries at a current density of 0.1 C

[0084]

[0085] According to the test results in Table 1, when the SiO composite materials prepared in Examples 1 - 6 were used as the negative electrode materials, the capacity retention rates after 100 cycles and the 10C / 0.1C capacity retention rates were much higher than those of the comparative example, demonstrating that the SiO composite materials in the above examples of the present invention all have high cycle stability and excellent rate performance as the negative electrode materials.

[0086] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be combined arbitrarily without conflict.

Claims

1. A SiO x A method for preparing a negative electrode material, characterized in that: include: Mixing silicon powder, transition metal oxide powder and tin powder uniformly to form a mixed powder; The mixed powder is added into a ball mill and ball-milled under an inert atmosphere to obtain SiOx-based powder; The SiOx-based powder is placed in a heating furnace and kept warm at a preset temperature, and the obtained powder is crushed after being discharged to obtain a SiOx-based negative electrode material.

2. SiO according to claim 1 x A method for preparing a negative electrode material, characterized in that: The silicon powder, transition metal oxide powder and tin powder are uniformly mixed to form a mixed powder, wherein the transition metal oxide powder is any one or more of Fe2O3 powder, Fe3O4 powder, CoO powder, Co2O3 powder, MnO powder and CuO powder.

3. SiO according to claim 1 x A method for preparing a negative electrode material, characterized in that: The silicon powder, transition metal oxide powder and tin powder are uniformly mixed to form a mixed powder, wherein the silicon powder accounts for 15-51% of the total mass of the mixed powder, and the atomic mass ratio of the tin powder to the transition metal in the transition metal oxide powder is less than 2:

1.

4. SiO according to claim 1 x A method for preparing a negative electrode material, characterized in that: The silicon powder, transition metal oxide powder and tin powder are uniformly mixed to form a mixed powder, wherein the silicon powder accounts for 25-40% of the total mass of the mixed powder.

5. SiO according to claim 1 x A method for preparing a negative electrode material, characterized in that: The mixed powder is added into a ball mill and ball milled under the protection of an inert atmosphere, including: using oscillating ball milling, the ball-to-material ratio during the ball milling process is 25:1-50:1, the vibration frequency of the ball mill is 800-1400rpm, and the ball milling time is 2-16h.

6. SiO according to claim 1 x A method for preparing a negative electrode material, characterized in that: The mixed powder is added into a ball mill and ball milled under the protection of an inert atmosphere, including: planetary ball milling, a ball-to-material ratio of 25:1-50:1 during the ball milling process, a vibration frequency of the ball mill of 300-500 rpm, and a ball milling time of 10-50 hours.

7. SiO according to claim 1 x A method for preparing a negative electrode material, characterized in that: The SiOx-based powder is placed in a heating furnace and kept warm at a preset temperature, wherein the heating furnace is a box-type heating furnace or a tubular heating furnace, the preset temperature is 300-600° C., and the temperature is kept warm for 2-5 hours, and an inert protective gas is introduced during the heat preservation process.

8. A SiO x Base negative electrode material, characterized in that The method is prepared by any one of claims 1 to 7.

9. A negative electrode plate, characterized in that: Comprising a carbon coating layer and the SiO x Based negative electrode material, the carbon coating layer is coated on the SiO x The surface of the base negative electrode material.

10. A lithium ion battery, characterized in that: Comprising the SiO according to claim 8 x Base negative electrode material, or The negative electrode sheet according to claim 9.

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