Fiber electrode and preparation method thereof

Abstract

The invention relates to the technical field of a carbon-based negative electrode material for a lithium ion battery, and particularly discloses a carbon-based fiber electrode and a preparation method thereof, Ir is doped into the surface of a graphite felt fiber material through an ion implantation method, and the metal Ir can be used as a catalyst for preparing a carbon nanotube through a subsequent ALD method while improving the electrochemical activity of the carbon-based electrode. Researches show that a proper amount of metal Ir can improve the low-temperature capacity achievement rate of the battery when the fiber electrode is used as a negative electrode, but excessive Ir can cause negative effects, so that the ion implantation amount of the metal Ir needs to be controlled to 1.2 * 10 < 4 >-7.2 * 10 < 8 > ions / cm < 2 >. Besides, when Ir and Ru are compositely injected, a more excellent test effect can be obtained, the low-temperature battery capacity achievement rate exceeds 95%, and the method is suitable for battery use requirements of new energy automobiles.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of carbon-based negative electrode materials for lithium-ion batteries (H01M4 / 1393), and in particular to a carbon-based fiber electrode and a preparation method thereof. BACKGROUND

[0002] New energy vehicles are one of the hottest topics in the automotive industry today, representing the future trend of the transportation sector towards cleaner and more sustainable development. As one of the important components of new energy vehicles, the activity of lithium batteries in low temperature environment is a key technical challenge, which directly affects the winter range and charging performance of electric vehicles. Based on this, the present application expects to improve the low temperature activity of lithium batteries from the electrode material, and then improve the battery capacity achievement rate under low temperature conditions. SUMMARY

[0003] The present application aims to provide a preparation method of a carbon-based fiber electrode, which can obtain a carbon-based fiber electrode with excellent low temperature activity.

[0004] The technical solution of the present application is as follows: A preparation method of a carbon-based fiber electrode, comprising the following steps: Pre-treatment: soaking the graphite felt fiber material in anhydrous ethanol for 12-15h to obtain an oil-removed graphite felt fiber material, then washing several times with deionized water until there is no ethanol residue, and then air-drying the graphite felt fiber material to obtain a pre-treated graphite felt fiber material; Ion implantation of Ir: placing the pre-treated graphite felt fiber material into a metal vapor vacuum arc power ion implantation device, selecting metal Ir for ion implantation, ion voltage is 60-75keV, Ir metal ion implantation amount is 1.2×10 4 ions / cm 2 -7.2×10 8 ions / cm 2 ; ALD method for preparing carbon nanotubes: placing the graphite felt fiber material into an atomic layer deposition device and introducing ethylene, and allowing the carbon atoms in the ethylene to spontaneously accumulate on the surface of the metal Ir to form a carbon nanotube structure by plasma discharge, wherein the plasma discharge power is 55-60W, the discharge time of a single cycle is 1.5-2.0s, the flow rate of ethylene is 75-90sccm, and each cycle includes purging the residual gas in the atomic layer deposition device with an inert gas, finally obtaining a carbon-based fiber electrode containing Ir and carbon nanotubes.

[0005] Preferably, the soaking time is 12h.

[0006] Preferably, the ion voltage is 60keV.

[0007] Preferably, the plasma discharge power is 55W.

[0008] Preferably, the ethylene flow rate is 75 sccm.

[0009] Preferably, the discharge time of a single cycle is 1.5s.

[0010] Preferably, in the ion implantation step, 1.2 × 10⁻⁶ ions are also implanted. 6 ions / cm 2 -7.2×10 8 ions / cm 2 The metal Ru.

[0011] Furthermore, the present invention also provides a carbon-based fiber electrode, which is prepared by the above method.

[0012] This invention introduces Ir into the surface of graphite felt fiber materials via ion implantation. Metallic Ir not only improves the electrochemical activity of carbon-based electrodes but also serves as a catalyst for the subsequent ALD (Alternating Discharge) process to prepare carbon nanotubes. Studies have shown that an appropriate amount of metallic Ir can improve the low-temperature capacity achievement rate of batteries when the fiber electrode is used as the negative electrode; however, excessive Ir has negative effects. Therefore, the amount of metallic Ir implanted needs to be controlled at 1.2 × 10⁻⁶. 4 ions / cm 2 -7.2×10 8 ions / cm 2 Furthermore, when Ir and Ru are injected together, even better experimental results can be obtained, with a low-temperature battery capacity achievement rate exceeding 95%, which is suitable for the battery usage requirements of new energy vehicles. Detailed Implementation

[0013] The technical effects of the present invention will be verified through specific embodiments below, but the implementation of the present invention is not limited thereto.

[0014] Example 1 Pretreatment: The graphite felt fiber material was soaked in anhydrous ethanol for 12 hours to obtain the degreased graphite felt fiber material. Then, it was cleaned several times with deionized water and ultrasonic cleaning until there was no ethanol residue. The graphite felt fiber material was then left to stand and air dry to obtain the pretreated graphite felt fiber material. Ion implantation (Ir): The pretreated graphite felt fiber material was placed in a metal vapor vacuum arc ion implantation device, and Ir metal was selected for ion implantation. The ion voltage was 60 keV, and the Ir metal ion implantation amount was 1.2 × 10⁻⁶. 4 ions / cm 2 ; ALD method for preparing carbon nanotubes: the graphite felt fiber material is put into an atomic layer deposition device and ethylene is introduced, and carbon atoms in the ethylene are spontaneously accumulated on the metal Ir surface to form a carbon nanotube structure through plasma discharge, wherein the plasma discharge power is 55 W, the discharge time of a single cycle is 1.5 s, the flow rate of ethylene is 75 sccm, each cycle includes purging the residual gas in the atomic layer deposition device with an inert gas, and finally a carbon-based fiber electrode containing Ir and carbon nanotubes is obtained.

[0015] Example 2 Pre-treatment: the graphite felt fiber material is soaked in anhydrous ethanol for 12 h to obtain an oil-removed graphite felt fiber material, and then the graphite felt fiber material is cleaned several times with deionized water and ultrasonic cleaning until there is no ethanol residue, and then the graphite felt fiber material is placed and air-dried to obtain a pre-treated graphite felt fiber material; Ion implantation of Ir: the pre-treated graphite felt fiber material is placed in a metal vapor vacuum arc power ion implantation device, and metal Ir is selected for ion implantation, the ion voltage is 60 keV, and the ion implantation amount of Ir metal is 2.5×10 5 ions / cm 2 ; ALD method for preparing carbon nanotubes: the graphite felt fiber material is put into an atomic layer deposition device and ethylene is introduced, and carbon atoms in the ethylene are spontaneously accumulated on the metal Ir surface to form a carbon nanotube structure through plasma discharge, wherein the plasma discharge power is 55 W, the discharge time of a single cycle is 1.5 s, the flow rate of ethylene is 75 sccm, each cycle includes purging the residual gas in the atomic layer deposition device with an inert gas, and finally a carbon-based fiber electrode containing Ir and carbon nanotubes is obtained.

[0016] Example 3 Pre-treatment: the graphite felt fiber material is soaked in anhydrous ethanol for 12 h to obtain an oil-removed graphite felt fiber material, and then the graphite felt fiber material is cleaned several times with deionized water and ultrasonic cleaning until there is no ethanol residue, and then the graphite felt fiber material is placed and air-dried to obtain a pre-treated graphite felt fiber material; Ion implantation of Ir: the pre-treated graphite felt fiber material is placed in a metal vapor vacuum arc power ion implantation device, and metal Ir is selected for ion implantation, the ion voltage is 60 keV, and the ion implantation amount of Ir metal is 2.5×10 7 ions / cm 2 ; Carbon nanotubes are prepared by ALD method: Graphite felt fiber material is placed in an atomic layer deposition (ALD) apparatus and ethylene is introduced. Carbon atoms in the ethylene spontaneously accumulate on the surface of metal Ir through plasma discharge to form a carbon nanotube structure. The plasma discharge power is 55W, the discharge time of a single cycle is 1.5s, the ethylene flow rate is 75sccm, and each cycle includes purging the residual gas in the ALD apparatus with inert gas. Finally, a carbon-based fiber electrode containing Ir and carbon nanotubes is obtained.

[0017] Example 4 Pretreatment: The graphite felt fiber material was soaked in anhydrous ethanol for 12 hours to obtain the degreased graphite felt fiber material. Then, it was cleaned several times with deionized water and ultrasonic cleaning until there was no ethanol residue. The graphite felt fiber material was then left to stand and air dry to obtain the pretreated graphite felt fiber material. Ion implantation (Ir): The pretreated graphite felt fiber material was placed in a metal vapor vacuum arc ion implantation device, and Ir metal was selected for ion implantation. The ion voltage was 60 keV, and the Ir metal ion implantation amount was 7.2 × 10⁻⁶. 8 ions / cm 2 ; Carbon nanotubes are prepared by ALD method: Graphite felt fiber material is placed in an atomic layer deposition (ALD) apparatus and ethylene is introduced. Carbon atoms in the ethylene spontaneously accumulate on the surface of metal Ir through plasma discharge to form a carbon nanotube structure. The plasma discharge power is 55W, the discharge time of a single cycle is 1.5s, the ethylene flow rate is 75sccm, and each cycle includes purging the residual gas in the ALD apparatus with inert gas. Finally, a carbon-based fiber electrode containing Ir and carbon nanotubes is obtained.

[0018] Example 5 Pretreatment: The graphite felt fiber material was soaked in anhydrous ethanol for 12 hours to obtain the degreased graphite felt fiber material. Then, it was cleaned several times with deionized water and ultrasonic cleaning until there was no ethanol residue. The graphite felt fiber material was then left to stand and air dry to obtain the pretreated graphite felt fiber material. Ion implantation with Ir and Ru: The pretreated graphite felt fiber material was placed in a metal vapor vacuum arc ion implantation device, and Ir and Ru were selected for ion implantation. The ion voltage was 60 keV, and the Ir ion implantation amount was 2.4 × 10⁻⁶. 7 ions / cm 2 The Ru metal ion implantation amount was 2.4 × 10⁻⁶. 7 ions / cm 2 ; ALD method for preparing carbon nanotubes: the graphite felt fiber material is put into an atomic layer deposition device and ethylene is introduced, and carbon atoms in the ethylene are spontaneously accumulated on the metal Ir / Ru surface to form a carbon nanotube structure through plasma discharge, wherein the plasma discharge power is 55 W, the discharge time of a single cycle is 1.5 s, the flow rate of ethylene is 75 sccm, each cycle includes purging the residual gas in the atomic layer deposition device with an inert gas, and finally a carbon-based fiber electrode containing Ir / Ru and carbon nanotubes is obtained.

[0019] Comparative Example 1 Pre-treatment: the graphite felt fiber material is soaked in anhydrous ethanol for 12 h to obtain an oil-removed graphite felt fiber material, and then the graphite felt fiber material is cleaned several times with deionized water combined with ultrasonic cleaning until there is no ethanol residue, and then the graphite felt fiber material is air-dried to obtain a pre-treated graphite felt fiber material. ALD method for preparing carbon nanotubes: the graphite felt fiber material is put into an atomic layer deposition device and ethylene is introduced, and carbon atoms in the ethylene are spontaneously accumulated on the metal Ir surface to form a carbon nanotube structure through plasma discharge, wherein the plasma discharge power is 55 W, the discharge time of a single cycle is 1.5 s, the flow rate of ethylene is 75 sccm, each cycle includes purging the residual gas in the atomic layer deposition device with an inert gas, and finally a carbon-based fiber electrode containing carbon nanotubes is obtained.

[0020] Comparative Example 2 Pre-treatment: the graphite felt fiber material is soaked in anhydrous ethanol for 12 h to obtain an oil-removed graphite felt fiber material, and then the graphite felt fiber material is cleaned several times with deionized water combined with ultrasonic cleaning until there is no ethanol residue, and then the graphite felt fiber material is air-dried to obtain a pre-treated graphite felt fiber material. Ion implantation of Ir: the pre-treated graphite felt fiber material is put into a metal vapor vacuum arc power ion implantation device, and metal Ir is selected for ion implantation, the ion voltage is 60 keV, and the ion implantation amount of Ir metal is 1.5×10 12 ions / cm 2 ; ALD method for preparing carbon nanotubes: the graphite felt fiber material is put into an atomic layer deposition device and ethylene is introduced, and carbon atoms in the ethylene are spontaneously accumulated on the metal Ir surface to form a carbon nanotube structure through plasma discharge, wherein the plasma discharge power is 55 W, the discharge time of a single cycle is 1.5 s, the flow rate of ethylene is 75 sccm, each cycle includes purging the residual gas in the atomic layer deposition device with an inert gas, and finally a carbon-based fiber electrode containing Ir and carbon nanotubes is obtained.

[0021] Next, the carbon-based fiber electrodes in Examples 1-5 and Comparative Examples 1-2 are used as anodes to assemble lithium batteries. The batteries are discharged at a current of 1 A at room temperature (25°C) and at 0°C, respectively, and the capacity achievement rate at 0°C relative to that at room temperature is calculated. To ensure the comparability of the experimental data, we need to ensure that the conditions in the examples and comparative examples are the same except for the amount of Ir / Ru implanted in the carbon-based fiber electrodes. The conditions include the battery separator, current collector, shell, etc., and the content of carbon nanotubes prepared by ALD method. The test results are shown in Table 1.

[0022] Table 1 Test data of each sample As can be seen from Table 1, by implanting Ir on the surface of the graphite felt fiber material by ion implantation, the metal Ir can improve the electrochemical activity of the carbon-based electrode and also serve as a catalyst for the subsequent preparation of carbon nanotubes by ALD method. Studies have shown that an appropriate amount of metal Ir can improve the low-temperature capacity achievement rate of the fiber electrode when used as an anode, but too much Ir will have a negative impact, so the amount of metal Ir implanted needs to be controlled at 1.2×10 4 ions / cm 2 -7.2×10 8 ions / cm 2 In addition, when Ir and Ru are implanted together, better test results can be obtained.

[0023] The above is only a preferred embodiment of the present application, and it should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A method of preparing a carbon-based fiber electrode, characterized by, The preparation method of the carbon-based fiber electrode comprises the following steps: Pre-treatment: soaking the graphite felt fiber material in anhydrous ethanol for 12-15 h to obtain an oil-removed graphite felt fiber material, then cleaning the graphite felt fiber material with deionized water for several times until no ethanol residue is left, and then air-drying the graphite felt fiber material to obtain a pre-treated graphite felt fiber material; Ion implantation of Ir: The pretreated graphite felt fiber material was placed into a metal vapor vacuum arc power ion implantation device, and Ir metal was selected for ion implantation. The ion voltage was 60-75 keV, and the Ir metal ion implantation amount was 1.2 x 1016 ions / cm2. 4 -7.2 x 1016 ions / cm2 2 -7.2 x 1016 ions / cm2 8 -7.2 x 1016 ions / cm2 2 ; ALD method for preparing carbon nanotubes: placing the graphite felt fiber material into an atomic layer deposition device and introducing ethylene, and allowing carbon atoms in the ethylene to spontaneously accumulate on the surface of the metal Ir to form a carbon nanotube structure by plasma discharge, wherein the plasma discharge power is 55-60 W, the discharge time of a single cycle is 1.5-2.0 s, the flow rate of the ethylene is 75-90 sccm, and each cycle includes purging the residual gas in the atomic layer deposition device with an inert gas, and finally obtaining a carbon-based fiber electrode containing Ir and carbon nanotubes.

2. A process according to claim 1, wherein the process is carried out at a temperature of from 20 to 100°C. The soaking time is 12 h.

3. A preparation method as described in claim 1, characterized in that, The ion voltage is 60 keV.

4. A preparation method as described in claim 1, characterized in that, The plasma discharge power is 55 W.

5. A preparation method as described in claim 1, characterized in that, The flow rate of the ethylene is 75 sccm.

6. A preparation method as described in claim 1, characterized in that, The discharge time of a single cycle is 1.5 s.

7. A carbon-based fiber electrode, characterized by, The carbon-based fiber electrode is prepared by the method of any one of claims 1-6.

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