Three-dimensional flexible self-supporting carbon cloth-nickel-trinickel disulfide nano porous network lithium ion battery negative electrode and preparation method thereof
By adopting a three-dimensional flexible self-supporting carbon cloth-nickel-tri-nickel disulfide nanoporous network structure of lithium-ion battery negative electrode, the problem of active components falling off caused by volume changes during charging and discharging is solved, and high cycle stability and rate performance are improved.
Patent Information
- Application Number
- CN202311791771.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-25
- Publication Date
- 2025-06-27
Smart Images
Figure CN120221589A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of anodes of lithium-ion batteries, and relates to a three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network anode of a lithium-ion battery and a preparation method thereof. Background Art
[0002] Energy, as the support point for the continuous development of human society, is the driving force for promoting social progress in all aspects. Since the utilization of non-renewable energy sources such as fossil fuels cannot be restored in the short term, and at the same time, with the continuous increase in people's energy demand, the overuse of fossil fuels brings climate problems such as the greenhouse effect, posing a severe challenge to the living environment of mankind. The research on renewable energy sources such as solar energy and wind energy is also the focus of continuous development, but they can only output energy and cannot store energy, making it difficult to meet people's living needs in modern society. Therefore, the research on secondary battery technologies that can convert electrical energy and chemical energy into each other is of great significance.
[0003] Lithium-ion batteries have advantages such as fast charge and discharge, high charge and discharge efficiency, no memory effect, excellent cycle performance, long service life, wide operating temperature range, low self-discharge power, and no pollution to the environment, and have become the most commercially successful secondary batteries. Currently, they have been widely used in the fields of energy storage, intelligent electronic devices, electric vehicles, etc. However, with the continuous development of society and the continuous improvement of living quality, products such as wearable electronic devices, flexible electronic devices and components, and electric vehicles have raised higher requirements for the performance of secondary batteries. Since the capacity of the anode material graphite in lithium-ion batteries has reached its limit and cannot meet the growing quality and practical needs, the development of new electrode materials has become an irresistible trend. In order to meet the increasing performance requirements, replacing traditional graphite with transition metal oxides is one of the main measures in recent years. Transition metal sulfides are regarded as promising candidate materials for anodes of lithium-ion batteries. Among all transition metal sulfides, nickel trisulfide has a relatively high theoretical specific capacity of 445 mAh g -1 and has thus received extensive attention.
[0004] Jiabao Li et al. reported the content of using Ni3S2@NC nanocomposites as high-performance anodes of lithium-ion batteries (Chem. Eng. J 2019, 378, 1, 122108). Ni3S2 nanoparticles encapsulated in interconnected N-doped porous carbon (Ni3S2@NC) were prepared by a simple freeze-drying method and subsequent in-situ transformation. The Ni3S2@NC nanocomposite, conductive agent, and binder were mixed in a mass ratio of 8:1:1 in deionized water to form a uniform slurry, which was then coated on a clean copper foil and vacuum-dried at 120 °C overnight to obtain the anode of the lithium-ion battery.
[0005] The method and the negative electrode of the lithium-ion battery prepared thereby have the following deficiencies: (1) Since a binder is used in the preparation of the negative electrode of the lithium-ion battery, the Ni3S2@NC nanocomposite and carbon black are bonded to the copper foil. The binder itself is not conductive, which will hinder electron transport, increase electrode polarization and impedance, and result in poor rate performance; (2) During the charge and discharge process of the lithium-ion battery, the insertion and extraction of lithium ions will cause huge volume changes. The negative electrode of the lithium-ion battery prepared by this method does not have the ability to effectively buffer the volume changes during the charge and discharge process. The binding force between the active components bonded by the binder and between the active components and the copper foil is also relatively limited, and the active components are prone to fall off and fail during the huge volume change process of charge and discharge. Summary of the Invention
[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode for a lithium-ion battery and a preparation method thereof, so as to simplify the production process of the negative electrode of the lithium-ion battery, avoid the shedding of active components during the charge and discharge process of the lithium-ion battery, and effectively improve the cycle performance and rate performance of the negative electrode of the lithium-ion battery.
[0007] The three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode provided by the present invention is composed of a flexible carbon cloth, a metal nickel layer, and nickel trisulfide. The metal nickel layer is a continuous metal layer deposited on the surface of the flexible carbon cloth. The metal nickel layer wraps the flexible carbon cloth, and nickel trisulfide forms a nickel trisulfide layer with a nanoporous network structure on the surface of the flexible carbon cloth wrapped by the metal nickel layer.
[0008] In the technical solution of the above three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode, the preferred thickness of the metal nickel layer is 50~200 nm.
[0009] In the technical solution of the above three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode, the preferred thickness of the nickel trisulfide layer is 5 nm~50 nm.
[0010] In the technical solution of the above three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode, the preferred size of the cluster unit of the nickel trisulfide nanoporous network is 20 nm~500 nm.
[0011] In the technical solution of the above three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode, the carbon cloth wrapped by the metal nickel layer serves as a current collector to improve the conductivity of the negative electrode, and nickel trisulfide serves as a lithium storage active material.
[0012] The present invention also provides a method for preparing the above-mentioned three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode, and the steps are as follows:
[0013] (1) The carbon cloth is successively ultrasonically cleaned in acetone, absolute ethanol, and deionized water for half an hour and then vacuum dried. Then, the cleaned carbon cloth is immersed in a mixed solution of concentrated nitric acid and concentrated sulfuric acid, and hydrophilic treatment is carried out at 80 °C for 3 h. After taking it out, it is washed with absolute ethanol and deionized water and vacuum dried to obtain pretreated carbon cloth;
[0014] The carbon cloth model is W0S1011, and the volume ratio of concentrated nitric acid to concentrated sulfuric acid in the mixed solution of concentrated nitric acid and concentrated sulfuric acid is 3:1;
[0015] (2) The pretreated carbon cloth obtained in step (1) is immersed in an aqueous solution of ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid. At 60 °C, in a three-electrode system, the pretreated carbon cloth is used as the working electrode, a platinum sheet is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode. Under the voltage condition of 1.8 V, a constant voltage electrodeposition reaction is carried out at a constant temperature of 60 °C for 60 s. During the electrodeposition reaction, a metal nickel layer grows on the surface of the carbon cloth. After the electrodeposition reaction is completed, a current collector is obtained;
[0016] In the above preparation method, in the aqueous solution of ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid, the concentration of ethylenediamine dihydrochloride is 1.5-2 mol / L, the concentration of nickel chloride hexahydrate is 0.8-1.2 mol / L, and the concentration of boric acid is 0.3-0.7 mol / L.
[0017] (3) The current collector obtained in step (2) is immersed in a solution of thiourea and nickel chloride hexahydrate in deionized water. In a three-electrode system, the prepared current collector is used as the working electrode, a platinum sheet is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode. Under the voltage condition of -1.245 V to 0.125 V, a certain number of cycles of cyclic voltammetry sweeping is carried out at a constant temperature of 26 °C. During the deposition process, nickel trisulfide grows on the surface of the current collector. After the electrodeposition process is completed, a flexible three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode is prepared.
[0018] In the above preparation method, in the solution of thiourea and nickel chloride hexahydrate in deionized water, the concentration of nickel chloride hexahydrate is 0.01-0.03 mol / L, and the concentration of thiourea is 1.3-1.8 mol / L.
[0019] In the above preparation method, the concentrations of the components in the solution of thiourea and nickel chloride hexahydrate in deionized water, the time, voltage, and temperature of the electrodeposition reaction in step (3), etc. will affect the crystal structure and quantity of the nickel trisulfide nanoporous network grown on the surface of the carbon cloth wrapped by the metal nickel layer, and further affect the thickness and microscopic morphology of the nickel trisulfide layer.
[0020] In step (1) of the above preparation method, the temperature of vacuum drying does not exceed 100 °C.
[0021] In the three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode provided by the present invention, nickel trisulfide is the lithium storage active material, and the carbon cloth wrapped with nickel mainly plays the role of improving the conductivity of the electrode. This negative electrode uses the carbon cloth wrapped with nickel as the substrate and nickel trisulfide as the lithium storage active material. This nanoporous network structure can effectively alleviate the volume expansion effect generated during the charge and discharge process of the lithium-ion battery. The nickel trisulfide layer is formed by nickel trisulfide growing on the surface of the carbon cloth wrapped with nickel. The nickel trisulfide layer has a nanoporous network structure, and the nanoporous network structure will grow into the carbon cloth wrapped with nickel and partially overlap and interpenetrate with the carbon cloth wrapped with nickel. Therefore, the nickel trisulfide nanoporous network is stably combined with the carbon cloth wrapped with nickel, and no binder is required, which is beneficial to increasing the binding force between the active substances and between the active substances and the substrate, making it difficult for the active substances and carbon to fall off from the substrate. In addition, due to the nanoporous network structure of nickel trisulfide, the specific surface area of the negative electrode of the lithium-ion battery is relatively large, which helps to provide more active sites for the insertion of lithium ions, and at the same time makes the electrolyte easy to penetrate into the gaps of the negative electrode, enabling the electrolyte to contact the negative electrode more fully. The combined effect of the above various factors makes the negative electrode provided by the present invention have obvious advantages in specific capacity compared with existing materials, with a lower irreversible capacity and excellent cycle stability and rate performance.
[0022] Compared with the prior art, the present invention has the following beneficial technical effects:
[0023] 1. The three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode provided by the present invention is composed of a carbon cloth, a metal nickel layer, and nickel trisulfide. The metal nickel layer wraps the carbon cloth, and nickel trisulfide forms a nickel trisulfide layer with a nanoporous network structure on the outer surface of the carbon cloth wrapped with the metal nickel layer. The nanoporous network structure in this negative electrode can effectively buffer the volume expansion generated during the charge and discharge process of the lithium-ion battery. Therefore, the nickel trisulfide layer is not easily detached due to the huge volume expansion during the charge and discharge process. At the same time, the nickel trisulfide layer is formed by embedding nickel trisulfide growing on the surface of the carbon cloth wrapped with the metal nickel layer. The nickel trisulfide layer is stably combined with the carbon cloth wrapped with the metal nickel layer, which is beneficial to increasing the binding force between the active substances and between the active substances and the substrate, making it difficult for the nickel trisulfide layer to fall off. The negative electrode of the lithium-ion battery with a nanoporous network structure has a large specific surface area, which can provide more active sites for the insertion of lithium ions, and at the same time makes the electrolyte easy to penetrate into the gaps of the negative electrode and contact the negative electrode more fully. The above factors are all beneficial to improving the cycle stability of this negative electrode.
[0024] 2. The three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode provided by the present invention does not require the use of a binder. There is a high binding force and extremely low interfacial resistance between the components. Compared with the prior art using a binder, the negative electrode provided by the present invention will not hinder electron transport, increase electrode polarization and impedance due to the presence of the binder, and has excellent cycle performance and rate performance. At the same time, the specific capacity of this negative electrode also has an advantage over existing materials, and the irreversible capacity is relatively low.
[0025] 3. Assembling the negative electrode provided by the present invention into a lithium-ion battery, after 410 cycles under the condition of a charge-discharge current density of 1 mA / cm 2 , the capacity no longer decays and maintains a relatively high specific capacity. At the same time, the Coulomb efficiency stabilizes above 95% after 10 cycles, showing very excellent cycle performance. It has a very good capacity retention rate at different rates. At the same time, the battery negative electrode prepared by the method of the present invention has good capacity performance.
[0026] 4. The process of the preparation method of the three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode provided by the present invention is simpler than the prior art, has no special requirements for production equipment and process conditions, and has the characteristics of being easy to realize large-scale production and popularization and application. Description of the Drawings
[0027] Figure 1 It is the SEM photograph of the CC / Ni current collector prepared in Example 1.
[0028] Figure 2 It is the SEM photograph of the surface of the negative electrode prepared in Example 1.
[0029] Figure 3 It is the TEM spectrum of the negative electrode prepared in Example 1.
[0030] Figure 4 It is the constant current charge-discharge cycle performance curve of the lithium-ion battery prepared in Example 1.
[0031] Figure 5 It is the rate performance curve of the lithium-ion battery prepared in Example 1.
[0032] Figure 6 It is the SEM photograph of the surface of the negative electrode prepared in Example 2.
[0033] Figure 7 It is the constant current charge-discharge cycle performance curve of the lithium-ion battery prepared in Example 2.
[0034] Figure 8 It is the SEM photograph of the surface of the negative electrode prepared in Example 3.
[0035] Figure 9It is the constant current charge-discharge cycle performance curve of the lithium-ion battery prepared in Example 3. Detailed implementation mode
[0036] The following further illustrates the three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode and its preparation method provided by the present invention through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art make some non-essential improvements and adjustments to the present invention according to the above-mentioned invention content for specific implementation, which still fall within the protection scope of the present invention.
[0037] Example 1
[0038] In this example, a preparation method of a three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode is provided, and the steps are as follows:
[0039] (1) The W0S1011 type carbon cloth is successively ultrasonically cleaned in acetone, absolute ethanol, and deionized water for half an hour and then vacuum dried. Then the cleaned carbon cloth is immersed in a mixed solution of concentrated nitric acid and concentrated sulfuric acid with a volume ratio of 3:1, and hydrophilic treatment is carried out at 80 °C for 3 h. After taking it out, it is cleaned with absolute ethanol and deionized water and vacuum dried to obtain a pretreated carbon cloth.
[0040] (2) 90 mmol of ethylenediamine dihydrochloride, 50 mmol of nickel chloride hexahydrate, and 25 mmol of boric acid are dissolved in 50 mL of deionized water to form an ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid mixed aqueous solution. The pretreated carbon cloth obtained in step (1) is immersed in the ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid mixed aqueous solution. At 60 °C, in a three-electrode system, the pretreated carbon cloth is used as the working electrode, the platinum sheet is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode. Under the voltage condition of 1.8 V, a constant voltage electrodeposition reaction is carried out at a constant temperature of 60 °C for 60 s. During the electrodeposition reaction process, the metal nickel layer is wrapped on the outer surface of the carbon cloth to form a carbon cloth wrapped with a metal nickel layer. After the reaction is completed, a current collector is obtained.
[0041] (3) Dissolve 1 mmol of NiCl2·6H2O and 75 mmol of CH4N2S in a mixed solution of 50 ml of deionized water to form a solution of nickel chloride hexahydrate - thiourea in deionized water. Immerse the current collector obtained in step (2) in the solution of nickel chloride hexahydrate - thiourea in deionized water. Under a three - electrode system, use the prepared current collector as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. At a voltage condition of -1.245 V to 0.125 V and a constant temperature of 26 °C, perform cyclic voltammetry sweeping 5 times. During the deposition process, nickel trisulfide grows on the surface of the current collector. After the electrodeposition process is completed, a three - dimensional flexible self - supporting carbon cloth - nickel - nickel trisulfide nanoporous network electrode is prepared.
[0042] Figure 1 is the SEM photograph of the carbon cloth wrapped with the metallic nickel layer prepared in step (1) of this example. It can be seen from Figure 1 that the metallic nickel layer deposited in step (2) continuously and uniformly wraps the surface of the carbon cloth, and the thickness of the metallic nickel layer is about 100 nm. Figure 2 is the SEM spectrum of the three - dimensional flexible self - supporting carbon cloth - nickel - nickel trisulfide nanoporous network electrode after electrodeposition in step (3) of this example. Figure 3 is the TEM spectrum of the electrode. After step (3), the substance with a network - like structure is nickel trisulfide grown on the surface of the carbon cloth wrapped with the metallic nickel layer. The thickness of the nickel trisulfide layer is about 10 nm, and the cluster unit size of the nickel trisulfide nanoporous network is about 50 nm.
[0043] Next, use the negative electrode prepared in this example to make a lithium - ion battery and conduct performance tests.
[0044] Use a metallic lithium sheet as the counter electrode, the negative electrode prepared in this example as the working electrode, a microporous polypropylene as the separator, and a mixed solution of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) containing 1 M lithium hexafluorophosphate (LiPF6) as the electrolyte. In this electrolyte, the volume ratio of EC, DMC, and DEC is 1:1:1. Assemble a lithium - ion battery in a glove box filled with argon with the content of water and oxygen both less than 1 ppm. Use a constant - current charge - discharge instrument of model NEWARE BTS - 610 to test the obtained lithium - ion battery. When testing, the current density is 1 mA / cm 2 , and the voltage range is 0.01~3 V (vs. Li / Li + ), and the test temperature is room temperature. The test results are as shown in Figure 4 . It can be seen from Figure 4 that the lithium - ion battery assembled with the negative electrode of this example has a charge - discharge current density of 1 mA / cm 2After cycling 410 times under the given conditions, the capacity hardly decays any more and maintains a high specific capacity. At the same time, the Coulombic efficiency stabilizes above 95% after 10 cycles. When the charge-discharge current density is in the range of 1 - 8 mA / cm 2 and cycling 200 times, the rate performance of the lithium-ion battery prepared in Example 1 is tested. The results are as Figure 5 shown. As can be seen from Figure 5 , the lithium-ion battery assembled with the negative electrode of this embodiment has very good capacity retention at different current densities. As can also be seen from Figures 4 - 5 , the negative electrode provided in this embodiment has a high specific capacity and reversible capacity retention rate. This indicates that the three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode prepared by the method of the present invention has excellent cycle stability and rate performance.
[0045] Example 2
[0046] In this embodiment, a method for preparing a three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode is provided, and the steps are as follows:
[0047] (1) The W0S1011 type carbon cloth is successively ultrasonically cleaned in acetone, absolute ethanol, and deionized water for half an hour and then vacuum dried. Then the cleaned carbon cloth is immersed in a mixed solution with a volume ratio of concentrated nitric acid to concentrated sulfuric acid of 3:1, and hydrophilic treatment is carried out at 80 °C for 3 h. After taking it out, it is cleaned with absolute ethanol and deionized water and vacuum dried to obtain a pretreated carbon cloth.
[0048] (2) 100 mmol of ethylenediamine dihydrochloride, 40 mmol of nickel chloride hexahydrate, and 20 mmol of boric acid are dissolved in 50 mL of deionized water to form an ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid mixed aqueous solution. The pretreated carbon cloth obtained in step (1) is immersed in the ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid mixed aqueous solution. Under the three-electrode system at 60 °C, the pretreated carbon cloth is used as the working electrode, the platinum sheet is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode. Under the condition of a voltage of 1.8 V and a constant temperature of 60 °C, a constant voltage electrodeposition reaction is carried out for 60 s. During the electrodeposition reaction, a metal nickel layer is wrapped on the outer surface of the carbon cloth to form a carbon cloth wrapped with a metal nickel layer. After the reaction is completed, a current collector is obtained.
[0049] (3) Dissolve 0.5 mmol of NiCl2·6H2O and 90 mmol of CH4N2S in a mixed solution of 50 ml of deionized water to form a solution of nickel chloride hexahydrate - thiourea in deionized water. Immerse the current collector obtained in step (2) in the solution of nickel chloride hexahydrate - thiourea in deionized water. Under a three - electrode system, use the prepared current collector as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. At a voltage condition of - 1.245 V to 0.125 V and a constant temperature of 26 °C, perform cyclic voltammetry scanning 3 times. During the deposition process, Ni3S2 grows on the surface of the current collector. After the electrodeposition process is completed, a three - dimensional flexible self - supporting carbon cloth - nickel - nickel trisulfide nanoporous network electrode is prepared.
[0050] In this example, the thickness of the metallic nickel layer is about 80 nm. Figure 6 is the SEM photograph of the nickel trisulfide nanoporous network prepared in step (3) of this example. It can be seen from Figure 6 that the nickel trisulfide prepared in step (3) has a nanoporous network structure. The thickness of the nickel trisulfide nanoporous network is about 5 nm, and the cluster unit size of the nickel trisulfide nanoporous network is about 20 nm.
[0051] Next, use the negative electrode prepared in this example to fabricate a lithium - ion battery and conduct performance tests.
[0052] Use a metallic lithium sheet as the counter electrode, the negative electrode prepared in this example as the working electrode, a microporous polypropylene as the separator, and a mixed solution of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) containing 1 M lithium hexafluorophosphate (LiPF6) as the electrolyte. In this electrolyte, the volume ratio of EC, DMC, and DEC is 1:1:1. Assemble a lithium - ion battery in a glove box filled with argon with the water and oxygen content both lower than 1 ppm. Use a constant current charge - discharge instrument of model NEWARE BTS - 610 to test the obtained lithium - ion battery. When testing, the current density is 1 mA / cm 2 , the voltage range is 0.01 - 3 V (vs. Li / Li + ), and the test temperature is room temperature. The test results are as shown in Figure 7 . It can be seen from Figure 7 that the lithium - ion battery assembled with the negative electrode of this example has almost no capacity decay and maintains a high specific capacity after 400 cycles under the condition of a charge - discharge current density of 1 mA / cm 2 . At the same time, the Coulomb efficiency stabilizes above 95% after 10 cycles.
[0053] Example 3
[0054] In this embodiment, a method for preparing a three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode is provided, and the steps are as follows:
[0055] (1) The W0S1011 type carbon cloth is successively ultrasonically cleaned in acetone, absolute ethanol, and deionized water for half an hour and then vacuum dried. Then, the cleaned carbon cloth is immersed in a mixed solution of concentrated nitric acid and concentrated sulfuric acid with a volume ratio of 3:1, and hydrophilic treatment is carried out at 80 °C for 3 h. After taking it out, it is washed with absolute ethanol and deionized water and vacuum dried to obtain pretreated carbon cloth.
[0056] (2) 100 mmol of ethylenediamine dihydrochloride, 60 mmol of nickel chloride hexahydrate, and 15 mmol of boric acid are dissolved in 50 mL of deionized water to form a mixed aqueous solution of ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid. The pretreated carbon cloth obtained in step (1) is immersed in the mixed aqueous solution of ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid. In a three-electrode system at 60 °C, the pretreated carbon cloth is used as the working electrode, a platinum sheet is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode. Under the voltage condition of 1.8 V, a constant voltage electrodeposition reaction is carried out at a constant temperature of 60 °C for 60 s. During the electrodeposition reaction, a metal nickel layer wraps around the outer surface of the carbon cloth to form a carbon cloth wrapped with a metal nickel layer, and a current collector is obtained after the reaction is completed.
[0057] (3) 1.5 mmol of NiCl2·6H2O and 75 mmol of CH4N2S are dissolved in a mixed solution of 50 ml of deionized water to form a mixed deionized water solution of nickel chloride hexahydrate-thiourea. The current collector obtained in step (2) is immersed in the mixed deionized water solution containing nickel chloride hexahydrate-thiourea. In a three-electrode system, the prepared current collector is used as the working electrode, a platinum sheet is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode. Under the voltage condition of -1.245 V to 0.125 V, cyclic voltammetry scanning is carried out 7 times at a constant temperature of 26 °C. During the deposition process, nickel trisulfide grows on the surface of the current collector, and a three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode is prepared after the electrodeposition process is completed.
[0058] In this embodiment, the thickness of the metal nickel layer is about 120 nm. Figure 8 is the SEM photograph of the Ni3S2 nanoporous network prepared in step (3) of this embodiment. It can be seen from Figure 8 that the nickel trisulfide prepared in step (3) has a nanoporous network structure. The thickness of the nickel trisulfide nanoporous network is about 30 nm, and the cluster unit size of the nickel trisulfide nanoporous network is about 100 nm.
[0059] Next, a lithium-ion battery is fabricated using the negative electrode prepared in this embodiment and its performance is tested.
[0060] Using a lithium metal sheet as the counter electrode, the negative electrode prepared in this example as the working electrode, a microporous polypropylene as the separator, and a mixed solution of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) containing 1 M lithium hexafluorophosphate (LiPF6) as the electrolyte. In this electrolyte, the volume ratio of EC, DMC, and DEC is 1:1:1. A lithium-ion battery is assembled in a glove box filled with argon with the water and oxygen content both lower than 1 ppm. A constant current charge-discharge instrument of model NEWARE BTS-610 is used to test the obtained lithium-ion battery. During the test, the current density is 1 mA / cm 2 , and the voltage range is 0.01~3 V (vs. Li / Li + ), and the test temperature is room temperature. The test results are as Figure 9 shown. It can be seen from Figure 9 that the lithium-ion battery assembled with the negative electrode of the lithium-ion battery of this example has almost no capacity decay and maintains a high specific capacity after 400 cycles under the condition of a charge-discharge current density of 1 mA / cm 2 . At the same time, the Coulomb efficiency is stable above 95% after 10 cycles.
[0061] Example 4
[0062] In this example, a method for preparing a three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode is provided, and the steps are as follows:
[0063] (1) The W0S1011 type carbon cloth is ultrasonically cleaned in acetone, absolute ethanol, and deionized water for half an hour in sequence and then vacuum dried. Then the cleaned carbon cloth is immersed in a mixed solution with a volume ratio of concentrated nitric acid to concentrated sulfuric acid of 3:1, and hydrophilic treatment is carried out at 80 °C for 3 h. After taking it out, it is cleaned with absolute ethanol and deionized water and vacuum dried to obtain the pretreated carbon cloth.
[0064] (2) 75 mmol of ethylenediamine dihydrochloride, 60 mmol of nickel chloride hexahydrate, and 35 mmol of boric acid are dissolved in 50 mL of deionized water to form an ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid mixed aqueous solution. The pretreated carbon cloth obtained in step (1) is immersed in the ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid mixed aqueous solution. Under a three-electrode system at 60 °C, the pretreated carbon cloth is used as the working electrode, a platinum sheet is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode. Under the condition of a voltage of 1.8 V, a constant voltage electrodeposition reaction is carried out at a constant temperature of 60 °C for 60 s. During the electrodeposition reaction, a metal nickel layer wraps around the outer surface of the carbon cloth to form a carbon cloth wrapped with a metal nickel layer. After the reaction is completed, a current collector is obtained.
[0065] (3) Dissolve 1.5 mmol of NiCl2·6H2O and 90 mmol of CH4N2S in a mixed solution of 50 ml of deionized water to form a mixed solution of nickel chloride hexahydrate-thiourea in deionized water. Immerse the current collector obtained in step (2) in the mixed solution of nickel chloride hexahydrate-thiourea in deionized water. Under a three-electrode system, use the prepared current collector as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. Under the voltage condition of -1.245 V to 0.125 V and at a constant temperature of 26 °C, perform cyclic voltammetry scanning 7 times. During the deposition process, nickel trisulfide grows on the surface of the current collector. After the electrodeposition process is completed, a flexible three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode is prepared.
[0066] In this embodiment, the thickness of the metal nickel layer is about 200 nm. Figure 8 is the SEM photograph of the Ni3S2 nanoporous network prepared in step (3) of this embodiment. It can be seen from Figure 8 that the nickel trisulfide prepared in step (3) has a nanoporous network structure. The thickness of the nickel trisulfide nanoporous network is about 50 nm, and the cluster unit size of the nickel trisulfide nanoporous network is about 500 nm.
[0067] Example 5
[0068] In this embodiment, a method for preparing a three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network negative electrode is provided, and the steps are as follows:
[0069] (1) Ultrasonically clean the W0S1011 type carbon cloth in acetone, absolute ethanol, and deionized water for half an hour each, and then vacuum dry it. Then immerse the cleaned carbon cloth in a mixed solution with a volume ratio of concentrated nitric acid to concentrated sulfuric acid of 3:1, perform hydrophilic treatment at 80 °C for 3 h, take it out, wash it with absolute ethanol and deionized water, and vacuum dry it to obtain a pretreated carbon cloth.
[0070] (2) Dissolve 80 mmol of ethylenediamine dihydrochloride, 40 mmol of nickel chloride hexahydrate, and 20 mmol of boric acid in 50 mL of deionized water to form a mixed aqueous solution of ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid. Immerse the pretreated carbon cloth obtained in step (1) in the mixed aqueous solution of ethylenediamine dihydrochloride-nickel chloride hexahydrate-boric acid. Under a three-electrode system at 60 °C, use the pretreated carbon cloth as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. Under the voltage condition of 1.8 V, perform a constant voltage electrodeposition reaction at a constant temperature of 60 °C for 60 s. During the electrodeposition reaction process, a metal nickel layer is wrapped on the outer surface of the carbon cloth to form a carbon cloth wrapped with a metal nickel layer. After the reaction is completed, a current collector is obtained.
[0071] (3) Dissolve 0.5 mmol of NiCl2·6H2O and 80 mmol of CH4N2S in a mixed solution of 50 ml of deionized water to form a solution of nickel chloride hexahydrate-thiourea in deionized water. Immerse the current collector obtained in step (2) in the solution of nickel chloride hexahydrate-thiourea in deionized water. Under a three-electrode system, use the prepared current collector as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. At a voltage condition of -1.245 V to 0.125 V and a constant temperature of 26 °C, perform cyclic voltammetry scanning 3 times. During the deposition process, nickel trisulfide grows on the surface of the current collector. After the electrodeposition process is completed, a flexible three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode is prepared.
[0072] In this embodiment, the thickness of the metallic nickel layer is about 50 nm. Figure 8 is the SEM photograph of the Ni3S2 nanoporous network prepared in step (3) of this embodiment. It can be seen from Figure 8 that the nickel trisulfide prepared in step (3) has a nanoporous network structure. The thickness of the nickel trisulfide nanoporous network is about 5 nm, and the cluster unit size of the nickel trisulfide nanoporous network is about 20 nm.
Claims
1. A three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nano-porous network anode for a lithium-ion battery, characterized in that It consists of carbon cloth, a nickel metal layer, and nickel trisulfide. The nickel metal layer is a current collector layer formed by electrodeposition on the surface of the carbon cloth to wrap it. The nickel metal layer wraps the carbon cloth, and nickel trisulfide forms a nickel trisulfide layer with a porous network structure on the surface of the carbon cloth wrapped by the nickel layer.
2. The three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode according to claim 1, characterized in that, The thickness of the nickel metal layer is 50 - 200 nm.
3. The three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode according to claim 1 or 2, characterized in that, The thickness of the Ni3S2 layer is 5 nm - 50 nm.
4. The three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode according to claim 1 or 2, wherein, The size of the nickel trisulfide nanoporous network is 50 nm - 500 nm.
5. The preparation method of the three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode according to any one of claims 1 to 4, characterized in that The steps are as follows: (1) Ultrasonically clean the carbon cloth in acetone, absolute ethanol, and deionized water for half an hour each in sequence, then vacuum dry it. Then immerse the cleaned carbon cloth in a mixed solution of concentrated nitric acid and concentrated sulfuric acid, and perform hydrophilic treatment at 80 °C for 3 h. After taking it out, wash it with absolute ethanol and deionized water and vacuum dry it to obtain pretreated carbon cloth; The carbon cloth model is W0S1011, and in the mixed solution of concentrated nitric acid and concentrated sulfuric acid, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1; (2) Immerse the pretreated carbon cloth obtained in step (1) in an aqueous solution of ethylenediamine dihydrochloride - nickel chloride hexahydrate - boric acid. Under a three - electrode system at 60 °C, use the pretreated carbon cloth as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. Under the voltage condition of 1.8 V, carry out a constant - voltage electrodeposition reaction at a constant temperature of 60 °C for 60 s. During the electrodeposition reaction, a nickel metal layer grows on the surface of the carbon cloth. After the stirring reaction is completed, a current collector is obtained; (3) Immerse the current collector obtained in step (2) in a solution of thiourea and cobalt chloride hexahydrate in deionized water. Under a three - electrode system, use the prepared current collector as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. Under the voltage condition of - 1.245 V - 0.125 V, at a constant temperature of 26 °C, perform cyclic voltammetry scanning for a certain number of times. During the deposition process, nickel trisulfide grows on the surface of the current collector. After the electrodeposition process is completed, a three - dimensional flexible self - supporting carbon cloth - nickel - nickel trisulfide nanoporous network electrode is prepared.
6. The preparation method of the three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode according to claim 5, characterized in that, The pretreatment time of the carbon cloth is 3 h.
7. The preparation method of the three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode according to any one of claims 6, characterized in that, In the aqueous solution of ethylenediamine dihydrochloride - nickel chloride hexahydrate - boric acid, the concentration of ethylenediamine dihydrochloride is 1.5 - 2 mol / L, the concentration of nickel chloride hexahydrate is 0.8 - 1.2 mol / L, and the concentration of boric acid is 0.3 - 0.7 mol / L.
8. The preparation method of the three-dimensional flexible self-supporting carbon cloth-nickel-nickel trisulfide nanoporous network electrode according to any one of claims 5 to 7, characterized in that, In the solution of thiourea and cobalt chloride hexahydrate in deionized water in step (3), the concentration of cobalt chloride hexahydrate is 0.02 mol / L, and the concentration of thiourea is 1.5 mol / L.