A method for surface modification of carbon fiber felt with nickel-phosphorus plating

Abstract

This invention discloses a method for surface modification of carbon fiber felt by nickel-phosphorus plating. First, the carbon fiber felt is degummed, ultrasonically cleaned in acetone solution, rinsed with deionized water, and then dried in an oven. The resulting carbon fiber felt is then roughened by immersing it in NaOH solution for a period of time, followed by rinsing with deionized water. Next, the carbon fiber felt is sensitized by immersing it in SnCl2 solution for a period of time, followed by rinsing with deionized water. Finally, the sensitized carbon fiber felt is activated by immersing it in AgNO3 solution for a period of time, followed by rinsing with deionized water. The carbon fiber felt is then immersed in a prepared chemical plating solution for a period of time. During the reaction, the ambient temperature must be maintained at 80℃±5℃, and ammonia solution must be added dropwise to maintain the pH value of the plating solution at 9-11. The chemical plating solution comprises NaH2PO2·H2O, NaC6H5O7·2H2O, and NiSO4·6H2O. The surface of the carbon fiber felt is then treated with lithium plating through nickel-phosphorus metal modification.

Description

Technical Field

[0001] This invention relates to the field of battery negative electrode current collector technology, and in particular to a method for surface modification of carbon fiber felt with nickel-phosphorus plating. Background Technology

[0002] Carbon fiber felt is a fiber with a carbon content exceeding 95%, produced by high-temperature pyrolysis of organic fibers such as polyacrylonitrile-based carbon fiber felt, viscose-based carbon fiber felt, and pitch-based carbon fiber felt. It not only possesses the intrinsic properties of carbon materials but also the processability of fibers. Carbon fiber felt exhibits a series of excellent properties, including high specific modulus, high specific strength, high temperature resistance, radiation resistance, low density, electrical conductivity, low coefficient of thermal expansion, and light weight, making it promising for applications in many fields.

[0003] Using carbon fiber felt as a current collector offers advantages such as lightweight, high strength, and high porosity. The inventors discovered that to preferentially deposit lithium metal in the lower structure (lithium-zinc alloy), improve the porosity utilization of the carbon fiber felt, and reduce expansion stress, a lithium-repellent treatment is applied to the carbon fiber felt. This treatment makes the lower structure (lithium-zinc alloy) of the composite negative electrode lithium-friendly and the upper structure (carbon fiber felt) lithium-repellent, guiding lithium metal deposition from bottom to top and effectively improving battery life. Therefore, when using carbon fiber felt as a current collector in combination with lithium-zinc alloy, a lithium-repellent treatment is necessary to increase the lithium affinity gradient between the lower structure (lithium-zinc alloy) and the upper structure (carbon fiber felt). This invention proposes a nickel-phosphorus plating modification method for the surface of carbon fiber felt to reduce its lithium affinity. Summary of the Invention

[0004] The purpose of this invention is to provide a method for modifying the surface of carbon fiber felt by nickel-phosphorus plating, which involves surface modification with nickel-phosphorus metal to perform lithium plating treatment on the surface of carbon fiber felt.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A method for surface modification of carbon fiber felt by nickel-phosphorus plating specifically includes the following steps:

[0007] S1. First, the carbon fiber felt is degummed, ultrasonically cleaned in acetone solution, then cleaned with deionized water and dried in an oven.

[0008] S2. The carbon fiber felt obtained in step S1 is roughened by soaking it in NaOH solution for a period of time and then washing it with deionized water.

[0009] S3. Sensitize the carbon fiber felt obtained in step S2 by soaking it in SnCl2 solution for a period of time, and then washing it with deionized water.

[0010] S4. The sensitized carbon fiber felt obtained in step S3 is activated by soaking the carbon fiber felt in AgNO3 solution for a period of time, and then taking it out and washing it with deionized water.

[0011] S5. Immerse the pretreated carbon fiber felt in the prepared chemical plating solution for a period of time. During the reaction, the ambient temperature should be maintained at 80℃±5℃, and an ammonia solution should be added dropwise to maintain the pH value of the plating solution in the range of 9-11. The chemical plating solution consists of NaH2PO2·H2O, NaC6H5O7·2H2O and NiSO4·6H2O.

[0012] Preferably, the chemical plating solution contains NaH2PO2·H2O at a concentration of 26 g / L, NaC6H5O7·2H2O at a concentration of 26 g / L, and NiSO4·6H2O at a concentration of 28 g / L.

[0013] Preferably, the soaking time in step S5 is 5 min to 45 min.

[0014] Preferably, in step S1, the temperature of the oven is controlled at 65℃±5℃, and the drying time is 2h±0.5h.

[0015] Preferably, the concentration of the NaOH solution in step S2 is 60 g / L ± 5 g / L.

[0016] Preferably, in step S2, the carbon fiber felt is immersed in a NaOH solution at 70℃±5℃ for 20min±10min.

[0017] Preferably, the concentration of the SnCl2 solution in step S3 is 10 g / L ± 2 g / L.

[0018] Preferably, in step S3, the carbon fiber felt is immersed in a SnCl2 solution at 40℃±5℃ for 30min±10min.

[0019] Preferably, the concentration of the AgNO3 solution in step S4 is 10 g / L ± 2 g / L.

[0020] Preferably, in step S4, the carbon fiber felt is immersed in an AgNO3 solution at 40℃±5℃ for 30min±10min.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] 1. Compared with the commonly used PdCl2 solution as the activation liquid, using AgNO3 as the activation liquid can achieve low-cost modification of nickel-phosphorus metal on the surface of carbon fiber felt, and the nickel-phosphorus modification on the surface of carbon fiber felt is more uniformly distributed.

[0023] 2. The nickel-phosphorus modified carbon fiber felt current collector prepared by the method of the present invention can effectively reduce the lithium affinity of carbon fiber felt. Its lighter weight can significantly improve the energy density of the battery. Moreover, by controlling the immersion time in the chemical plating solution, the amount of nickel and phosphorus modified on the surface of carbon fiber felt can be controlled. Too much nickel and phosphorus will reduce the porosity of carbon fiber felt.

[0024] 3. Using carbon fiber felt as the negative electrode current collector allows lithium metal to be preferentially deposited in the lower structure, improving the porosity utilization of the carbon fiber felt and reducing expansion stress. The carbon fiber felt is treated to be lithium-repellent, making the lower structure of the composite negative electrode lithium-friendly and the upper structure lithium-repellent, guiding lithium metal to be deposited from bottom to top. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 The chemical plating solution of this invention was characterized by SEM and EDS after 45 min of reaction.

[0027] Figure 2 The chemical plating solution of this invention was characterized by SEM and EDS after 15 min of reaction.

[0028] Figure 3 This invention relates to the test of the initial nucleation overpotential of lithium under different plating solution treatment times. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0030] Implementation examples

[0031] A method for surface modification of chemically plated nickel-phosphorus modified carbon fiber felt (CMNP) includes the following steps:

[0032] S1. First, the carbon fiber felt is degummed, ultrasonically cleaned in acetone solution for 20min±10min, then cleaned with deionized water and dried in an oven. The oven temperature is controlled at 65℃±5℃ and the drying time is 2h±0.5h.

[0033] S2. The carbon fiber felt obtained in step S1 is roughened by immersing it in a NaOH solution at 70℃±5℃ for 20min±10min. The concentration of the NaOH solution is 60g / L±5g / L. After immersion, it is washed with deionized water.

[0034] S3. Sensitize the carbon fiber felt obtained in step S2 by immersing it in a SnCl2 solution at 40℃±5℃ for 30min±10min. The concentration of the SnCl2 solution is 10g / L±2g / L. After immersion, rinse it with deionized water.

[0035] S4. Activate the sensitized carbon fiber felt obtained in step S3 by immersing the carbon fiber felt in an AgNO3 solution at 40℃±5℃ for 30min±10min. The concentration of the AgNO3 solution is 10g / L±2g / L. After immersion, rinse with deionized water.

[0036] S5. Immerse the pretreated carbon fiber felt in the prepared chemical plating solution for 5-45 minutes. The optimal amount of nickel-phosphorus modification is achieved within 30-45 minutes. During the reaction, the ambient temperature should be maintained at 80℃±5℃, and ammonia solution should be added dropwise to maintain the pH value of the plating solution in the range of 9-11. The chemical plating solution consists of NaH2PO2·H2O at a concentration of 26 g / L, NaC6H5O7·2H2O at a concentration of 26 g / L, and NiSO4·6H2O at a concentration of 28 g / L.

[0037] Example 1

[0038] A method for surface modification of chemically plated nickel-phosphorus modified carbon fiber felt (CMNP) includes the following steps:

[0039] S1. First, the carbon fiber felt is degummed, ultrasonically cleaned in acetone solution for 20 minutes, cleaned with deionized water, and then dried in an oven at 65°C for 2 hours.

[0040] S2. The carbon fiber felt obtained in step S1 is roughened by immersing it in a NaOH solution at 70°C for 20 minutes. The concentration of the solution is 60 g / L. After immersion, it is washed with deionized water.

[0041] S3. Sensitize the carbon fiber felt obtained in step S2 by immersing it in a SnCl2 solution at 40°C for 30 minutes. The concentration of the solution is 10 g / L. After immersion, rinse it with deionized water.

[0042] S4. The sensitized carbon fiber felt obtained in step S3 is activated by immersing it in AgNO3 solution at 40℃ for 30 minutes. The concentration of the solution is 10g / L. After immersion, it is washed with deionized water.

[0043] S5. Immerse the pretreated carbon fiber felt in the prepared chemical plating solution for 15 minutes. Maintain an ambient temperature of 80℃ during the reaction, and add ammonia solution dropwise to keep the pH of the plating solution between 9 and 11. The chemical plating solution consists of: NaH₂PO₂·H₂O (26 g / L), NaC₆H₅O₇·2H₂O (26 g / L), and NiSO₄·6H₂O (28 g / L). The surface of the carbon fiber felt contains 1% phosphorus and 3% nickel.

[0044] Example 2

[0045] The only difference from Example 1 is step S5.

[0046] S5. Immerse the pretreated carbon fiber felt in the prepared chemical plating solution for 30 minutes. Maintain an ambient temperature of 80℃ during the reaction, and add ammonia solution dropwise to keep the pH of the plating solution between 9 and 11. The chemical plating solution consists of: NaH₂PO₂·H₂O (26 g / L), NaC₆H₅O₇·2H₂O (26 g / L), and NiSO₄·6H₂O (28 g / L). The surface of the carbon fiber felt contains 6% phosphorus and 31% nickel.

[0047] Example 3

[0048] The only difference from Example 1 is step S5.

[0049] S5. Immerse the pretreated carbon fiber felt in the prepared chemical plating solution for 45 minutes. Maintain an ambient temperature of 80℃ during the reaction, and add ammonia solution dropwise to keep the pH of the plating solution between 9 and 11. The chemical plating solution consists of: NaH₂PO₂·H₂O (26 g / L), NaC₆H₅O₇·2H₂O (26 g / L), and NiSO₄·6H₂O (28 g / L). The surface of the carbon fiber felt contains 11% phosphorus and 50% nickel.

[0050] Comparative Example 1

[0051] The only difference from Example 1 is step S5.

[0052] S5. Immerse the pretreated carbon fiber felt in the prepared chemical plating solution for 60 minutes. Maintain an ambient temperature of 80℃ during the reaction, and add ammonia solution dropwise to keep the pH of the plating solution between 9 and 11. The chemical plating solution consists of: NaH₂PO₂·H₂O (26 g / L), NaC₆H₅O₇·2H₂O (26 g / L), and NiSO₄·6H₂O (28 g / L). The surface of the carbon fiber felt contains 15% phosphorus and 68% nickel.

[0053] Comparative Example 2

[0054] The difference from Example 1 is that the carbon fiber felt was not treated in any way.

[0055] The carbon fiber felts prepared in Examples 1-3 and Comparative Examples 1-2 were used to test the lithium-repellent properties of the chemically plated nickel-phosphorus modified carbon fiber felt current collector (CMNP) by testing the initial nucleation overpotential.

[0056] Lithium initial nucleation overpotential test:

[0057] The initial lithium nucleation overpotential was tested when carbon fiber felt was treated in a chemical plating solution for different times and assembled with pure lithium to verify the effect of nickel-phosphorus chemical plating modification on the lithiophilicity of carbon fiber felt. The initial nucleation overpotentials of lithium metal on current collectors CM, CMP-15, CMNP-30, CMNP-45, and CMNP-60 were 140 mV, 158 mV, 162 mV, 169 mV, and 192 mV, respectively. With the increase of chemical plating solution treatment time, the initial lithium nucleation overpotential gradually increased, indicating that the lithium repellency of the current collector modified with nickel-phosphorus plating was improved. Although CMNP-60 had the highest initial lithium nucleation overpotential, the porosity of the carbon fiber felt was significantly reduced, which could not effectively suppress the volume expansion of lithium metal and instead reduced the cycle life of the battery.

[0058] The carbon fiber felt composite zinc alloy used in Examples 1-3 and Comparative Examples 1-2 was used to prepare a composite negative electrode, which was then assembled into a 0.25Ah soft-pack battery with a ternary positive electrode and subjected to charge-discharge cycle testing. Charge-discharge cycles were performed at a charging rate of 0.33C / 0.33C, and the number of cycles was recorded when the capacity retention reached 80%.

[0059] Cycle life Example 1 207 Example 2 282 Example 3 406 Comparative Example 1 133 Comparative Example 2 119

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for surface modification of carbon fiber felt by nickel-phosphorus plating, characterized in that, Specifically, the following steps are included: S1. First, the carbon fiber felt is degummed, ultrasonically cleaned in acetone solution, then cleaned with deionized water and dried in an oven. S2. The carbon fiber felt obtained in step S1 is roughened by soaking it in NaOH solution for a period of time and then washing it with deionized water. S3. Sensitize the carbon fiber felt obtained in step S2 by soaking it in SnCl2 solution for a period of time, and then washing it with deionized water. S4. The sensitized carbon fiber felt obtained in step S3 is activated by soaking the carbon fiber felt in AgNO3 solution for a period of time, and then taking it out and washing it with deionized water. S5. Immerse the pretreated carbon fiber felt in the prepared chemical plating solution for 5-45 minutes. During the reaction, the ambient temperature should be maintained at 80℃±5℃, and an ammonia solution should be added dropwise to maintain the pH value of the plating solution in the range of 9-11. The chemical plating solution consists of NaH2PO2·H2O with a concentration of 26g / L, NaC6H5O7·2H2O with a concentration of 26g / L, and NiSO4·6H2O with a concentration of 28g / L.

2. The method for surface modification of nickel-phosphorus-plated carbon fiber felt according to claim 1, characterized in that, In step S1, the temperature of the oven is controlled at 65℃±5℃, and the drying time is 2h±0.5h.

3. The method for surface modification of nickel-phosphorus-plated carbon fiber felt according to claim 1, characterized in that, In step S2, the concentration of the NaOH solution is 60 g / L ± 5 g / L.

4. The method for surface modification of nickel-phosphorus-plated carbon fiber felt according to claim 3, characterized in that, In step S2, the carbon fiber felt is immersed in a NaOH solution at 70℃±5℃ for 20min±10min.

5. The method for surface modification of nickel-phosphorus-plated carbon fiber felt according to claim 1, characterized in that, In step S3, the concentration of the SnCl2 solution is 10 g / L ± 2 g / L.

6. The method for surface modification of nickel-phosphorus-plated carbon fiber felt according to claim 1, characterized in that, In step S3, the carbon fiber felt is immersed in a SnCl2 solution at 40℃±5℃ for 30min±10min.

7. The method for surface modification of nickel-phosphorus-plated carbon fiber felt according to claim 1, characterized in that, In step S4, the concentration of the AgNO3 solution is 10 g / L ± 2 g / L.

8. The method for surface modification of nickel-phosphorus-plated carbon fiber felt according to claim 1, characterized in that, In step S4, the carbon fiber felt is immersed in AgNO3 solution at 40℃±5℃ for 30min±10min.

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