Current collector material preparation method and current collector material

Abstract

The invention discloses a preparation method of a current collector material, which comprises the following steps: placing porous nickel in a fluidized bed, introducing silane gas in an argon environment for silicon deposition, and cooling to room temperature after deposition to obtain a silicon / porous nickel material; then taking metal nickel as a target material, and carrying out PVD (Physical Vapor Deposition) deposition on the obtained silicon / porous nickel material to obtain a nickel-coated silicon material; and finally, coating the nickel-coated silicon material on the surface of a copper foil, and drying to obtain the nickel-coated silicon current collector material. The material can be used for manufacturing a negative current collector of a battery and can also be used as a current collector material of a battery without a negative electrode. Compared with the prior art, the material obtained by the method has higher anti-deformation strength compared with a porous carbon current collector material, realizes complete coating of nano silicon, can well isolate silicon from an electrolyte when being used as an electrode, reduces the consumption of lithium ions in the repeated charge-discharge cycle process of a battery, and improves the battery performance. And the cycle service life of the battery is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy batteries, in particular to a preparation method of a nickel-coated silicon current collector material and the prepared current collector material. BACKGROUND

[0002] In the prior art, the electrode current collector is usually prepared by foamed nickel metal current collector which is subjected to two CVD (chemical vapor deposition) operations in sequence to deposit nanosilicon and carbon on the surface of the metal current collector. For example, the Chinese patent application CN 118888676A. However, in the method of the patent, the nanosilicon and carbon are deposited unevenly due to the large pores of the foamed nickel metal, especially in large-scale production, which will lead to poor cycle performance of the battery due to uneven carbon deposition. At the same time, in the method, dangerous gases such as silane and alkane carbon source are used, and due to the need for one-step production, a closed furnace cannot be used, which has great safety hazards. In addition, when CVD is used for carbon deposition, carbon atoms will dissolve in the nickel metal at high temperature, and it is difficult to play a role in coating silicon or filling pores after cooling and precipitation. SUMMARY

[0003] In view of the above problems of the prior art, the present application aims to provide a current collector material with good coating and high strength and a preparation method thereof.

[0004] The preparation method of the current collector material comprises the following steps: S1: placing powdery porous nickel in a fluidized bed, introducing silane gas for deposition after heating to a certain temperature under an argon environment, closing the silane gas after a certain time of deposition, closing the argon after cooling to room temperature, and taking out the product to obtain a silicon / porous nickel material; S2: using metal nickel as a target material to perform PVD deposition on the silicon / porous nickel material prepared in step S1 to obtain a nickel-coated silicon material; S3: coating the nickel-coated silicon material prepared in step S2 on the surface of a copper foil, and drying to obtain a nickel-coated silicon current collector material. The coating can be performed by scraping, spraying, screen printing, etc.

[0005] Preferably, the pore size of the porous nickel used in step S1 is less than 10 nm.

[0006] Preferably, the porosity of the porous nickel used in step S1 is 50% to 80%. The porosity refers to the percentage of the pore volume in the bulk material to the total volume of the material in the natural state.

[0007] Preferably, the temperature in step S1 is 500-700 DEG C, and the time is 3-5 hours, that is, the temperature is raised to 500-700 DEG C under argon atmosphere, silane gas is introduced for silane deposition, the silane gas is turned off after setting the time, the temperature is lowered to room temperature, and then the argon is turned off, and the product is taken out, thereby obtaining the silicon / porous nickel material.

[0008] Preferably, in step S2, the background vacuum degree is controlled to be 1x10 -5 ~1x10 -3 Pa, and the working vacuum degree is 0.1-10 Pa. The background vacuum degree refers to the vacuum degree of the gas in a certain space by using a vacuum pumping system.

[0009] Preferably, the mass ratio of silicon to nickel of the current collector material after deposition in step S2 is 2:1-6:1.

[0010] Preferably, the PVD (physical vapor deposition) deposition method in step S2 is sputtering plating or evaporation plating.

[0011] A preferred scheme is that evaporation plating is used in step S2, and the specific operation steps are as follows: the silicon / porous nickel material is placed in an electron beam evaporation device, metal nickel is used as the target material, vacuum is drawn, the substrate temperature is set to 200-300 DEG C, the electron gun is started, the nickel target material is slowly heated to a molten state at low power, then the acceleration voltage is increased to start evaporation, the temperature is lowered after evaporation is completed, and the nickel-coated silicon material is taken out.

[0012] A preferred scheme is that sputtering plating is used in step S2, and the specific operation steps are as follows: the silicon / porous nickel material is placed in a direct current sputtering device, the target material is metal nickel, vacuum is drawn, the temperature is raised to 200-300 DEG C, argon gas is slowly introduced, the argon gas inlet rate is adjusted to achieve the required vacuum degree for PVD deposition, and the nickel-coated silicon material is obtained.

[0013] The present application claims protection for the preparation method of the current collector material, and also claims the current collector material prepared by the method.

[0014] The present application has the following beneficial effects: (1) the method first uses porous nickel with a specific pore size as a metal skeleton for silicon deposition, effectively controls the size of nanosilicon, and uses the high strength of the metal skeleton to inhibit the stress influence caused by silicon expansion, has higher deformation resistance than porous carbon, and reduces the risk of negative electrode fragmentation or cell deformation; (2) then PVD technology is used to make nickel atoms grow and deposit in the pores of the porous nickel in which silicon has been deposited until the pores are completely blocked, and the nanosilicon is completely wrapped, which can well isolate the contact between silicon and electrolyte when used as an electrode, reduces the consumption of lithium ions in the repeated charge and discharge cycle process of the battery, and improves the cycle service life of the battery.

[0015] The current application provides a kind of current collector material and its preparation method. DETAILED DESCRIPTION

[0016] In order to make the person in this field better understand the technical scheme of the present application, the product of the present application will be further described in detail below in combination with examples.

[0017] The preparation method of the current collector material of the present application uses powdery porous nickel, and the porous nickel is placed in a fluidized bed to deposit silicon under argon environment by passing in silane gas, and then the silicon / porous nickel material is obtained after being cooled to room temperature. Then, the obtained silicon / porous nickel material is subjected to PVD deposition by using metal nickel as target material, and nickel-coated silicon material is obtained. Finally, the nickel-coated silicon material is coated on the surface of copper foil, and after drying, the nickel-coated silicon current collector material is obtained. When coating on the surface of copper foil, scraping, spraying or screen printing process can be used.

[0018] In the present application, the porous nickel with micrometer or millimeter level pores is used as the base material. First, silicon is deposited in the pores of the porous nickel, and then PVD deposition is carried out by using metal nickel with purity higher than 99.99% as target material to obtain nickel-coated silicon material. The nickel-coated silicon material thus obtained is completely coated with silicon and has good isolation property. When used as battery electrode, it can well isolate the contact between silicon and battery electrolyte, reduce the consumption of lithium ions in the process of repeated charge and discharge cycle of the battery, and improve the cycle service life of the battery. Example 1

[0019] S1: The porous nickel powder is placed in a fluidized bed, and after being heated to 500℃ under argon environment, silane gas is passed in, and after 4h of deposition, the silane gas is turned off, the argon is turned off after being cooled to room temperature, and the product is taken out to obtain silicon / porous nickel material; S2: The silicon / porous nickel material is placed in a direct current sputtering device, the target material is metal nickel, and the vacuum degree is extracted to 3×10 -4 Pa, and the argon gas is slowly passed in after being heated to 200℃. The argon gas inlet rate is controlled until the vacuum degree is 1Pa for PVD deposition. After 1h of deposition, nickel-coated silicon material is obtained; S3: The above material is coated on the surface of copper foil, and after drying, nickel-coated silicon negative electrode current collector material is obtained. Example 2

[0020] S1: The porous nickel powder is placed in a fluidized bed, and after being heated to 600℃ under argon environment, silane gas is passed in, and after 4h of deposition, the silane gas is turned off, the argon is turned off after being cooled to room temperature, and the product is taken out to obtain silicon / porous nickel material; S2: The silicon / porous nickel material is placed in an electron beam evaporation device, the target material is metal nickel, and the vacuum degree is extracted to 1×10 -4Pa, the substrate temperature was set to 200°C, the electron gun was started, and a low power (accelerating voltage 5 kV, beam current 100 mA) was set. After the nickel target was slowly heated to a molten state for 1-2 minutes, the accelerating voltage was set to 7 kV, and the beam current was set to 400 mA. Deposition was started, and after 2 hours, the temperature was lowered to take out the product, thereby obtaining a nickel-coated silicon material; S3: The above material was coated on the surface of a copper foil, and after drying, a nickel-coated silicon negative electrode current collector material was obtained. Example 3

[0021] S1: The porous nickel powder was placed in a fluidized bed, argon gas was introduced after the temperature was raised to 600°C, and deposition was performed for 4 hours. After the silane gas was turned off, the temperature was lowered to room temperature, and the argon gas was turned off. The product was taken out, thereby obtaining a silicon / porous nickel material. S2: The silicon / porous nickel material was placed in a direct current sputtering device, and a metal nickel target was used. The vacuum degree was reduced to 2x10 -5 Pa, the temperature was raised to 200°C, argon gas was slowly introduced, the argon gas inlet rate was controlled, and PVD deposition was performed until the vacuum degree was 1 Pa. After deposition for 1 hour, a nickel-coated silicon material was obtained. S3: The above material was coated on the surface of a copper foil, and after drying, a nickel-coated silicon negative electrode current collector material was obtained. Example 4

[0022] S1: The porous nickel powder was placed in a fluidized bed, argon gas was introduced after the temperature was raised to 700°C, and deposition was performed for 4 hours. After the silane gas was turned off, the temperature was lowered to room temperature, and the argon gas was turned off. The product was taken out, thereby obtaining a silicon / porous nickel material. S2: The silicon / porous nickel material was placed in a direct current sputtering device, and a metal nickel target was used. The vacuum degree was reduced to 3x10 -4 Pa, the temperature was raised to 200°C, argon gas was slowly introduced, the argon gas inlet rate was controlled, and PVD deposition was performed until the vacuum degree was 1 Pa. After deposition for 1 hour, a nickel-coated silicon material was obtained. S3: The above material was coated on the surface of a copper foil, and after drying, a nickel-coated silicon negative electrode current collector material was obtained.

[0023] Comparative Example 1 The difference from Example 1 is that PVD deposition was not performed, and the silicon / porous nickel material was directly coated on the surface of a copper foil.

[0024] Comparative Example 2 The difference from Example 1 is that porous nickel was not used, and instead, foamed nickel (pore size > 1 μm) was used.

[0025] Comparative Example 3 S1: Put the porous nickel powder into the fluidized bed, and after heating to 600 DEG C under argon environment, pass in silane gas, deposit for 4h, then close the silane gas, to obtain silicon / porous nickel material; S2: After reducing the temperature of the fluidized bed to 500 DEG C, pass in acetylene gas, maintain for 2h, then close the acetylene, continuously pass in argon to reduce to room temperature, to obtain carbon-coated nickel silicon material; S3: Coating the above material on the surface of copper foil, and after drying, obtaining carbon-coated nickel silicon negative electrode current collector material.

[0026] The negative electrode current collector material prepared in the above examples and comparative examples is used for button cell, and electrochemical performance test is carried out. The process method of using various materials as the current collector of button cell is completely consistent, and the configuration of electrolyte and other materials is also completely consistent. The final performance data is as follows:

[0027] From the table data, it can be seen that the button cell made of the nickel-coated silicon current collector material prepared by the method of the application has obvious advantages in battery charge-discharge efficiency parameters, cycle performance and current collector expansion rate. Among them, example 2 is the best.

[0028] Among them, in the argon glove box, the current collector material prepared by the above examples and comparative examples is used as the negative electrode current collector of each button cell, and each button cell is assembled on the battery tester for electrochemical cycle performance test. The charge-discharge voltage range is 0.01V to 1.5V, and the charge-discharge rate is 1C, and the charge-discharge efficiency is obtained.

[0029] The nickel-coated silicon material or carbon-coated nickel silicon material prepared in the above examples and comparative examples is subjected to gram capacity test, and the specific test process is: the actual mass of the nickel-coated silicon material or carbon-coated nickel silicon material in the button cell is calculated, the discharge capacity / mass=gram capacity is obtained, and the first discharge gram capacity and the gram capacity after 100 cycles are obtained.

[0030] The nickel-coated silicon and carbon-coated nickel silicon current collector of the above button cell is subjected to expansion test, and the specific test process is: the thickness D1 of the nickel-coated silicon and carbon-coated nickel silicon current collector of the button cell after rolling is tested, then the button cell is fully charged, then the button cell is disassembled, and the thickness D2 of the negative electrode sheet under full charge is measured, then the current collector expansion rate (current collector expansion rate=(D2-D1) / D1*100%) is calculated.

[0031] The parts not specifically described in the application can be realized by the general method or common method in the prior art, which will not be repeated here.

[0032] The above embodiments are only specific embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of patent protection of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, and these obvious replacement forms belong to the protection scope of the present application.

Claims

1. A method for preparing a current collector material, comprising the following steps: S1: placing powdered porous nickel in a fluidized bed, passing in silane gas for deposition after heating to a certain temperature in an argon environment, closing the silane gas after a certain time of deposition, closing the argon after cooling to room temperature, taking out the product, and obtaining a silicon / porous nickel material; S2: performing PVD deposition on the silicon / porous nickel material prepared in step S1 using metal nickel as a target material, and obtaining a nickel-coated silicon material; S3: coating the nickel-coated silicon material prepared in step S2 on the surface of a copper foil, and drying to obtain a nickel-coated silicon current collector material.

2. The negative current collector material production method according to claim 1, wherein The porous nickel used in step S1 has a pore size of less than 10 nm.

3. The method of claim 1, wherein: The porous nickel used in step S1 has a porosity of 50% to 80%.

4. The method of claim 1, wherein: The certain temperature in step S1 is 500 to 700℃, and the certain time is 3 to 5 hours. ​ 5. The method of claim 1, wherein: The PVD deposition method in step S2 is sputtering or evaporation plating.

6. The method of claim 5, wherein: In the PVD deposition in step S2, the base vacuum is controlled to be 1x10 -5 ~1x10 -3 Pa, and the working vacuum is controlled to be 0.1~10 Pa.

7. The method of claim 1, wherein: The mass ratio of silicon to nickel in the current collector material after deposition in step S2 is 2:1 to 6:

1.

8. The method of making a current collector material of claim 1, wherein: Step S2 specifically comprises placing the silicon / porous nickel material in an electron beam evaporation device, using metal nickel as a target material, vacuumizing, setting the substrate temperature to 200 to 300℃, starting the electron gun, slowly heating the nickel target material to a molten state at low power, then increasing the acceleration voltage to start evaporation, cooling and taking out after evaporation is completed, and obtaining a nickel-coated silicon material.

9. The method of claim 1, wherein: Step S2 specifically comprises placing the silicon / porous nickel material in a direct current sputtering device, using metal nickel as a target material, vacuumizing, heating to 200 to 300℃, slowly passing in argon, controlling the argon inlet rate to achieve the required vacuum degree for PVD deposition, and obtaining a nickel-coated silicon material.

10. A current collector material characterized by: The current collector material is prepared by any one of claims 1 to 9.

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