Method for preparing high-performance layered SiOx material with assistance of plasma pretreatment and application of high-performance layered SiOx material

Abstract

The invention relates to a method for preparing a high-performance layered SiOx material with assistance of plasma pretreatment and application of the method. The invention belongs to the field of lithium ion battery negative electrode materials. The invention aims to provide a method for preparing a high-performance layered SiOx material under the assistance of plasma pretreatment and application of the high-performance layered SiOx material. A plasma pretreatment method is adopted, hydroxyl on the surface of siloxyalkene is removed, oxygen vacancies are induced to be generated, and the purpose of regulating and controlling the oxygen content in the layered SiOx material is achieved. Meanwhile, a multi-element synergistic doping process is introduced, so that the SEI performance is improved. The layered SiOx material provided by the invention has good electrochemical performance, and has relatively high battery specific capacity when being used as a negative electrode of a lithium ion battery.

Description

Technical Field

[0001] The present invention belongs to the field of lithium ion battery negative electrode materials, and specifically relates to a method for preparing high-performance layered SiO2 with the assistance of plasma pretreatment. x Materials, methods and their applications. Background Art

[0002] As energy storage devices, improving the performance of lithium-ion batteries is crucial for the development of electric vehicles, consumer electronics, energy storage systems, and other fields. As a key component of lithium-ion batteries, the performance of negative electrode materials directly affects the overall performance of the battery. Although graphite negative electrode materials have mature processes and low costs, their energy density is close to the theoretical limit, making it difficult to meet the market demand for higher energy density batteries. Silicon negative electrode materials are considered to be the ideal choice for next-generation lithium-ion battery negative electrode materials due to their high theoretical specific capacity (4200mAh / g), low delithiation potential, and environmental friendliness.

[0003] During the lithium-ion battery deintercalation process, silicon-based materials undergo significant volume changes. This dramatic expansion effect leads to a rapid decay of battery capacity, which seriously restricts its widespread promotion in industrial applications. x The material can effectively alleviate the volume expansion problem of silicon during the cycle through its unique structural design, thereby maintaining the excellent cycle performance of the battery. x Too high oxygen content in the layered SiO will limit its lithium storage capacity. x The oxygen content in the material is of great significance. At the same time, appropriate element doping on the surface of the material helps to form a stable and uniform solid electrolyte interface (SEI), improving the SiO x electrochemical performance. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a plasma pretreatment assisted preparation method for high performance layered SiO x The plasma pretreatment method is used to remove the hydroxyl groups on the surface of siloxane and induce the generation of oxygen vacancies, thereby achieving the goal of regulating the layered SiO x The purpose of the present invention is to reduce the oxygen content in the material; at the same time, a multi-element synergistic doping process is introduced to improve the performance of SEI. x The material has good electrochemical properties and has a high battery specific capacity when used as the negative electrode of lithium-ion batteries.

[0005] The technical solutions of the present invention are as follows:

[0006] One of the purposes of the present invention is to provide a plasma pretreatment assisted preparation method for high performance layered SiO x The method of the material is carried out according to the following steps:

[0007] S1: evenly spread the layered siloxane material on a dielectric plate, place it in a plasma treatment chamber, evacuate the chamber, introduce a mixture of inert gas and working gas, adjust the radio frequency power for plasma treatment, and obtain layered siloxane containing oxygen vacancies;

[0008] S2: Heat treatment of the layered siloxane containing oxygen vacancies in an inert gas to obtain high-performance layered SiO x .

[0009] It is further defined that the preparation of the layered siloxene material in S1 is as follows: concentrated acid and a silicon metal compound are mixed and stirred for a period of time, followed by suction filtration, washing, and drying to obtain the layered siloxene material.

[0010] It is further defined that the concentrated acid is one or more of hydrofluoric acid, nitric acid, sulfuric acid, sulfurous acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid, lactic acid, acetic acid, and citric acid, with a concentration of 0.1 to 25 mol / L.

[0011] It is further defined that the silicon metal compound is one or more of vanadium silicide, calcium silicide, titanium silicide, cobalt silicide, tantalum silicide, iron silicide, cerium silicide, niobium silicide, copper silicide, hafnium silicide, zirconium silicide, nickel silicide, tungsten silicide, molybdenum silicide, chromium silicide, manganese silicide, lithium silicide, and sodium silicide.

[0012] It is further defined that the ratio of the silicon metal compound to the concentrated acid is 1 g: (10-100) mL.

[0013] Furthermore, the stirring time is limited to 0.5 to 24 hours.

[0014] It is further defined that the inert gas in S1 is argon or nitrogen, and the working gas is one or more of hydrogen, ammonia, phosphine, hydrogen sulfide, diborane, boron trifluoride, methane, and carbon tetrafluoride.

[0015] It is further defined that the flow ratio of the inert gas to the working gas in the mixed gas in S1 is 1:(1-50).

[0016] It is further defined that the radio frequency power in S1 is 1 to 300 W, and the plasma treatment time is 1 to 60 minutes.

[0017] It is further defined that the inert gas in S2 is argon or nitrogen.

[0018] It is further defined that the heat treatment temperature in S2 is 150-1000° C. and the time is 0.5-24 h.

[0019] The second object of the present invention is to provide a high performance layered SiO x .

[0020] The third object of the present invention is to provide a high performance layered SiO x Used as battery negative electrode active material.

[0021] The fourth object of the present invention is to provide a negative electrode plate, characterized in that the negative electrode plate is made of the high performance layered SiO x , binder and conductive agent.

[0022] A fifth object of the present invention is to provide an application of the above-mentioned negative electrode plate in a lithium-ion battery.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The present invention uses plasma pretreatment method to bombard the active layer of the siloxane surface with plasma, effectively removing the surface hydroxyl groups while inducing the generation of oxygen vacancies, and introduces a multi-element synergistic doping process to achieve the purpose of regulating the layered SiO x The oxygen content in the material and the purpose of improving SEI performance.

[0025] (2) The present invention can quantitatively control the layered SiO by controlling parameters such as plasma power, processing gas composition, and processing time. x The oxygen content of the material can also be controlled by controlling the type and ratio of plasma processing gas parameters to regulate the layered SiO x The type and content of doping elements in the material.

[0026] (3) High-performance layered SiO prepared by the present invention x Materials have made significant progress in improving the electrochemical performance of lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The layered SiO prepared in Example 1 x XRD pattern of the material;

[0028] Figure 2 The layered SiO prepared in Example 1 x SEM images of the materials;

[0029] Figure 3 The layered SiO prepared in Example 2 x XPS graph of the material;

[0030] Figure 4 The layered SiO prepared in Example 3 x Cycling performance diagram of the material at a current density of 0.5 A / g;

[0031] Figure 5 The layered SiO prepared in Example 4 xCycling performance diagram of the material at a current density of 0.5 A / g;

[0032] Figure 6 The layered SiO prepared in Example 5 x Rate performance diagram of the material;

[0033] Figure 7 The layered SiO prepared in Example 5 x Cycling performance diagram of the material at a current density of 0.5 A / g;

[0034] Figure 8 The layered SiO prepared in Comparative Example 1 x Cycling performance diagram of the material at a current density of 0.5 A / g. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are conventional in the art and can be obtained commercially by those skilled in the art unless otherwise specified.

[0037] Example 1

[0038] This embodiment provides a plasma pretreatment-assisted preparation of high-performance layered SiO x The material method comprises the following steps:

[0039] (1) Add 5 g of iron silicide to 300 mL of 15 mol / L hydrofluoric acid, mix well, stir for 12 h, wash with deionized water three times, and dry in vacuo at 80 °C for 10 h to obtain a layered siloxane material;

[0040] (2) 0.5 g of the layered siloxane material obtained in step (1) was evenly spread on a dielectric plate and placed in a plasma treatment chamber. After evacuation, nitrogen and ammonia were introduced with a nitrogen to ammonia flow ratio of 1:10. The RF power was adjusted to 20 W, and after plasma treatment for 10 minutes, a layered siloxane containing oxygen vacancies and doped with nitrogen was obtained;

[0041] (3) placing the layered siloxane containing oxygen vacancies obtained in step (2) in a tube furnace, heating the temperature to 600°C at a rate of 5°C / min under an argon atmosphere, and maintaining the temperature for 3 hours, and then naturally cooling to room temperature to obtain a high-performance layered SiO x Materials. The XRD of the obtained product is as follows Figure 1As shown, SEM Figure 2 As shown in the XRD diagram, the prepared layered SiO x In addition to the broad peak of amorphous SiO2, there is also a characteristic peak of Si, and no other impurity peaks, indicating that crystalline silicon is generated during the reaction. Through detailed analysis of the SEM images, it can be clearly seen that the prepared SiO x The material exhibits typical layered stacking structural characteristics, and its particle size is in the micron range; at the same time, it can be observed from the image that there are void structures between the layers.

[0042] The electrochemical performance of the silicon-carbon based composite anode material was tested by button cell. x The material is the active material, PAA is used as the binder, and the conductive agent Super P is added in a mass ratio of active material: PAA: Super P = 8:1:1. The mixture is then thoroughly stirred to form a negative electrode slurry. The slurry is then evenly coated on copper foil and baked in an oven at 80°C for 10 hours. After removal, it is rolled and pressed to form the negative electrode sheet.

[0043] The prepared negative electrode sheet was used as the negative electrode of the lithium-ion battery, metallic lithium was used as the positive electrode material, a polypropylene microporous membrane was used as the separator, and the electrolyte was an EC+DEC (volume ratio 1:1) solution with a LiPF6 concentration of 1 mol / L. The battery was assembled into a button cell in a glove box filled with argon atmosphere, and the charge and discharge cycle test was performed on the button cell.

[0044] The battery was first activated for 3 cycles at a current density of 0.1 A / g, and then subsequently tested at a current density of 0.5 A / g.

[0045] The electrochemical test showed that the charge cut-off voltage was 1.50V and the discharge cut-off voltage was 0.01V.

[0046] Example 2

[0047] This embodiment provides a plasma pretreatment-assisted preparation of high-performance layered SiO x The material method comprises the following steps:

[0048] (1) Add 2 g of nickel silicide to 100 mL of 10 mol / L phosphoric acid, mix well, stir for 24 h, wash with deionized water three times, and dry in vacuo at 80 °C for 10 h to obtain a layered siloxane material;

[0049] (2) 1 g of the layered siloxane material obtained in step (1) was evenly spread on a dielectric plate and placed in a plasma treatment chamber. After evacuation, argon and hydrogen were introduced with a flow ratio of argon to hydrogen of 1:15. The RF power was adjusted to 20 W, and after plasma treatment for 10 minutes, a layered siloxane containing oxygen vacancies was obtained.

[0050] (3) placing the layered siloxane containing oxygen vacancies obtained in step (2) in a tube furnace, heating the temperature to 400°C at a rate of 5°C / min under an argon atmosphere, and maintaining the temperature for 1 hour, and then naturally cooling to room temperature to obtain a high-performance layered SiO x The XPS of the obtained product is as follows Figure 3 As shown, the peak fitting results show that the XPS spectrum of Si 2p is composed of Si 0 、Si 2+ and Si 4+ Composition, SiO was calculated based on the peak area ratio x The x value in is 1.26.

[0051] The prepared layered SiO x The materials are used to make negative electrode materials for lithium-ion batteries, and the batteries are tested for charge and discharge.

[0052] Other unmentioned places are the same as those in Example 1.

[0053] Example 3

[0054] This embodiment provides a plasma pretreatment-assisted preparation of high-performance layered SiO x The material method comprises the following steps:

[0055] (1) Add 2 g of nickel silicide to 100 mL of 10 mol / L phosphoric acid, mix well, stir for 24 h, wash with deionized water three times, and dry in vacuo at 80 °C for 10 h to obtain a layered siloxane material;

[0056] (2) 1 g of the layered siloxane material obtained in step (1) was evenly spread on a dielectric plate and placed in a plasma treatment chamber. After evacuation, argon and hydrogen were introduced with a flow ratio of argon to hydrogen of 1:15. The RF power was adjusted to 60 W, and after plasma treatment for 10 minutes, a layered siloxane containing oxygen vacancies was obtained.

[0057] (3) placing the layered siloxane containing oxygen vacancies obtained in step (2) in a tube furnace, heating the temperature to 400°C at a rate of 5°C / min under an argon atmosphere, and maintaining the temperature for 1 hour, and then naturally cooling to room temperature to obtain a high-performance layered SiO x Material.

[0058] The prepared layered SiO x The materials are used to make negative electrode materials for lithium-ion batteries, and the batteries are tested for charge and discharge.

[0059] Other unmentioned places are the same as those in Example 1.

[0060] The cycling performance of the obtained product at a current density of 0.5 A / g is as follows Figure 4shown.

[0061] Example 4

[0062] This embodiment provides a plasma pretreatment-assisted preparation of high-performance layered SiO x The material method comprises the following steps:

[0063] (1) Add 2 g of nickel silicide to 100 mL of 10 mol / L phosphoric acid, mix well, stir for 24 h, wash with deionized water three times, and dry in vacuo at 80 °C for 10 h to obtain a layered siloxane material;

[0064] (2) 1 g of the layered siloxane material obtained in step (1) was evenly spread on a dielectric plate and placed in a plasma treatment chamber. After evacuation, argon and hydrogen were introduced with a flow ratio of argon to hydrogen of 1:15. The RF power was adjusted to 60 W, and after plasma treatment for 15 minutes, a layered siloxane containing oxygen vacancies was obtained.

[0065] (3) placing the layered siloxane containing oxygen vacancies obtained in step (2) in a tube furnace, heating the temperature to 400°C at a rate of 5°C / min under an argon atmosphere, and maintaining the temperature for 1 hour, and then naturally cooling to room temperature to obtain a high-performance layered SiO x Material.

[0066] The prepared layered SiO x The materials are used to make negative electrode materials for lithium-ion batteries, and the batteries are tested for charge and discharge.

[0067] Other unmentioned places are the same as those in Example 1.

[0068] The cycling performance of the obtained product at a current density of 0.5 A / g is as follows Figure 5 shown.

[0069] Example 5

[0070] This embodiment provides a plasma pretreatment-assisted preparation of high-performance layered SiO x The material method comprises the following steps:

[0071] (1) Add 2 g of calcium silicide to 100 mL of 10 mol / L hydrochloric acid, mix well, stir for 12 h, wash with deionized water three times, and vacuum dry at 80 ° C for 10 h to obtain a layered siloxane material;

[0072] (2) 1 g of the layered siloxane material obtained in step (1) was evenly spread on a dielectric plate and placed in a plasma treatment chamber. After evacuation, argon and diborane were introduced, with the flow ratio of argon to diborane being 1:5. The RF power was adjusted to 50 W, and after plasma treatment for 5 minutes, a layered siloxane containing oxygen vacancies and doped with boron was obtained;

[0073] (3) placing the layered siloxane containing oxygen vacancies obtained in step (2) in a tube furnace, heating the temperature to 500°C at a rate of 5°C / min under a nitrogen atmosphere, and maintaining the temperature for 1 hour, and then naturally cooling to room temperature to obtain a high-performance layered SiO x Material.

[0074] The prepared layered SiO x The materials are used to make negative electrode materials for lithium-ion batteries, and the batteries are tested for charge and discharge.

[0075] Other unmentioned places are the same as those in Example 1.

[0076] The rate performance of the obtained product is as follows Figure 6 As shown in Figure 2, the cycling performance at a current density of 0.5 A / g is shown in Figure 2. Figure 7 shown.

[0077] Comparative Example 1

[0078] This comparative example provides a layered SiO x The method for preparing the material comprises the following steps:

[0079] (1) 0.5 g of calcium silicide was added to 30 mL of 12 mol / L hydrochloric acid, mixed evenly, stirred for 10 h, washed with deionized water three times, and dried in vacuo at 80 ° C for 10 h to obtain a layered siloxane material;

[0080] (2) The layered siloxane material obtained in step (1) was placed in a tube furnace, heated to 450°C at a rate of 5°C / min under a nitrogen atmosphere, and kept at this temperature for 2 hours. After cooling naturally to room temperature, a layered SiO x Material.

[0081] The prepared layered SiO x The materials are used to make negative electrode materials for lithium-ion batteries, and the batteries are tested for charge and discharge.

[0082] Other unmentioned places are the same as those in Example 1.

[0083] The cycling performance of the obtained product at a current density of 0.5 A / g is as follows Figure 8 shown.

[0084] The layered SiO prepared in Examples 1 to 5 x Materials and layered SiO prepared in Comparative Example 1 x The material was used as the negative electrode material to assemble lithium-ion button batteries for constant current charge and discharge tests, and the results are listed in Table 1.

[0085] Table 1

[0086] Sample Description Reversible capacity (mAh / g) First coulombic efficiency (%) Example 1 1142.85 56.89 Example 2 1183.89 59.68 Example 3 1357.61 64.58 Example 4 1398.09 66.30 Example 5 1301.36 68.30 Comparative Example 1 863.10 49.39

[0087] The foregoing are merely preferred embodiments of the present invention. These embodiments are all different implementations based on the overall concept of the present invention. The scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A plasma pretreatment-assisted preparation of high-performance layered SiO x A method of material, characterized in that The method: S1: evenly spread the layered siloxane material on a dielectric plate, place it in a plasma treatment chamber, evacuate the chamber, introduce a mixture of inert gas and working gas, adjust the radio frequency power for plasma treatment, and obtain layered siloxane containing oxygen vacancies; S2: Heat treatment of the layered siloxane containing oxygen vacancies in an inert gas to obtain high-performance layered SiO x .

2. The method according to claim 1, characterized in that Preparation of the layered siloxene material in S1: Concentrated acid and a silicon metal compound are mixed and stirred for a period of time, followed by suction filtration, washing, and drying to obtain a layered siloxene material.

3. The method according to claim 2, characterized in that The concentrated acid is one or more of hydrofluoric acid, nitric acid, sulfuric acid, sulfurous acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid, lactic acid, acetic acid, and citric acid, with a concentration of 0.1 to 25 mol / L; the silicon metal compound is one or more of vanadium silicide, calcium silicide, titanium silicide, cobalt silicide, tantalum silicide, iron silicide, cerium silicide, niobium silicide, copper silicide, hafnium silicide, zirconium silicide, nickel silicide, tungsten silicide, molybdenum silicide, chromium silicide, manganese silicide, lithium silicide, and sodium silicide; the ratio of the silicon metal compound to the concentrated acid is 1 g: (10 to 100) mL, and stirring is performed for 0.5 to 24 hours.

4. The method according to claim 1, wherein The inert gas in S1 is argon or nitrogen, and the working gas is one or more of hydrogen, ammonia, phosphine, hydrogen sulfide, diborane, boron trifluoride, methane, and carbon tetrafluoride. The flow ratio of the inert gas to the working gas in the mixed gas is 1:(1-50).

5. The method according to claim 1, characterized in that In S1, the radio frequency power is 1 to 300 W, and the plasma treatment time is 1 to 60 minutes.

6. The method according to claim 1, characterized in that The inert gas in S2 is argon or nitrogen, the heat treatment temperature is 150-1000°C, and the time is 0.5-24h.

7. High-performance layered SiO prepared by the method according to any one of claims 1 to 6 x .

8. The high performance layered SiO according to claim 7 x Used as battery negative electrode active material.

9. A negative electrode plate, characterized in that: The negative electrode sheet is made of the high performance layered SiO x , binder and conductive agent.

10. Use of the negative electrode sheet according to claim 9 in a lithium-ion battery.

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