A three-dimensional self-supporting electrode, its fabrication method, and a lithium-ion battery

Abstract

This invention discloses a three-dimensional self-supporting electrode, its preparation method, and a lithium-ion battery. The preparation method includes the following steps: dissolving resorcinol and formaldehyde in a mixed solution of ethanol and water, adding ammonia, and stirring until fully mixed to obtain an organic polymer solution; adding an iron-containing compound to the organic polymer solution and stirring until fully dissolved to obtain a precursor solution; transferring the solution to a reaction vessel, placing a three-dimensional conductive substrate in the reaction vessel for hydrothermal reaction to obtain a three-dimensional self-supporting substrate containing an iron / carbon precursor; drying the three-dimensional self-supporting substrate containing the iron / carbon precursor, annealing it in an inert atmosphere, and naturally cooling it to room temperature to obtain a three-dimensional self-supporting electrode loaded with in-situ carbon-coated nano-Fe3O4. The preparation method provided by this invention is simple and low-cost, and the three-dimensional self-supporting electrode exhibits good cycle stability and rate performance, making it suitable for large-scale industrial production and widely applicable in the field of lithium-ion battery materials.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and in particular to a three-dimensional self-supporting electrode, its preparation method, and a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries possess advantages such as high energy density, long cycle life, and wide operating voltage range, making them widely used as power sources for various energy storage cabinets, electronic devices, and electric vehicles. Currently, graphite materials are widely used as mainstream lithium-ion battery anode materials due to their low resistivity, low cost, and abundant reserves. However, the theoretical specific capacity of graphite materials is relatively low (372 mAh / g), which severely limits the application of graphite anodes in high-energy-density devices. Therefore, finding anode materials with higher energy density is one of the main tasks in the development of next-generation lithium-ion batteries. Fe3O4 has attracted widespread attention from researchers due to its high theoretical specific capacity (924 mAh / g), abundant reserves, and low cost. However, due to the unique lithium storage mechanism of Fe3O4, the crystal structure of Fe3O4 changes during lithium-ion insertion / extraction, resulting in irreversible volume expansion, which seriously affects the electrochemical performance of lithium batteries. Therefore, it is necessary to explore a novel Fe3O4 electrode material. Summary of the Invention

[0003] To overcome the above-mentioned shortcomings and deficiencies of the prior art, the present invention aims to provide a method for preparing a three-dimensional self-supporting electrode, which forms carbon-coated nano-Fe3O4 in situ on a three-dimensional self-supporting substrate. The preparation process is simple, and the in-situ formed carbon-coated nano-Fe3O4 helps to increase the interaction between the nano-Fe3O4 active material and the conductive substrate, and can further improve the electron / ion transport performance of the nano-Fe3O4 material and its interface with the electrolyte.

[0004] Another object of the present invention is to provide a three-dimensional self-supporting electrode prepared by the above-described preparation method.

[0005] Another object of the present invention is to provide a lithium-ion battery based on the above-described three-dimensional self-supporting electrode.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for preparing a three-dimensional self-supporting electrode, comprising the following steps:

[0008] Resorcinol and formaldehyde were dissolved in a mixture of ethanol and water, and ammonia was added. The mixture was stirred until fully mixed to obtain an organic polymer solution.

[0009] An iron-containing compound is added to an organic polymer solution and stirred until fully dissolved to obtain a precursor solution. The solution is then transferred to a reaction vessel, and a three-dimensional conductive substrate is placed in the reaction vessel for hydrothermal reaction to obtain a three-dimensional self-supporting substrate containing an iron / carbon precursor. The iron-containing compound is at least one of ferric chloride, ferric nitrate nonahydrate, ferric sulfate, and ferric citrate.

[0010] After drying the three-dimensional self-supporting substrate containing iron / carbon precursors, it is annealed in an inert atmosphere and then naturally cooled to room temperature to obtain a three-dimensional self-supporting electrode loaded with in-situ carbon-coated nano-Fe3O4.

[0011] Preferably, the three-dimensional conductive substrate is foamed Ni, foamed Cu, or activated carbon cloth.

[0012] Preferably, the mass-to-volume ratio of resorcinol to formaldehyde is (1-5) g:(1-4) ml.

[0013] Preferably, the mass ratio of the iron-containing compound to the resorcinol is (1.5-2.5):0.1.

[0014] Preferably, the hydrothermal reaction conditions are: a reaction temperature of 160-200℃ and a reaction time of 8-12h.

[0015] Preferably, the annealing process specifically involves an annealing temperature of 400-800℃, an annealing time of 1-3 hours, and a heating rate of 5-10℃ / min.

[0016] Preferably, the inert atmosphere is at least one of N2 and Ar.

[0017] Preferably, placing the three-dimensional conductive substrate in the reaction vessel specifically involves:

[0018] The three-dimensional conductive substrate is placed in the reaction vessel at an angle of 40 to 50 degrees to the surface of the precursor solution.

[0019] Preferably, the volume ratio of ethanol to water is 1:(1-3).

[0020] Preferably, the three-dimensional conductive substrate undergoes the following pretreatment:

[0021] The three-dimensional conductive substrate is immersed in acid, then ultrasonically rinsed multiple times with deionized water and ethanol, and dried to obtain a clean conductive substrate after treatment and activation; more preferably, the acid is hydrochloric acid, sulfuric acid or nitric acid, with a concentration of 2-4M; the immersion time is 10-30 minutes; and the drying temperature is 30-80℃.

[0022] Preferably, the mass-to-volume ratio of resorcinol to ammonia is (0.1-0.5)g:(0.3-0.5)ml.

[0023] The present invention also provides a three-dimensional self-supporting electrode, which is prepared by the method described above.

[0024] The present invention also provides a lithium-ion battery, wherein the aforementioned three-dimensional self-supporting electrode is used as the negative electrode.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] (1) The method for preparing the three-dimensional self-supporting electrode of the present invention involves forming carbon-coated nano-Fe3O4 in situ on a three-dimensional self-supporting substrate. The preparation process is simple, and the carbon-coated nano-Fe3O4 formed in situ helps to increase the interaction between the nano-Fe3O4 active material and the conductive substrate, which can further improve the electron / ion transport performance of the nano-Fe3O4 material and its interface with the electrolyte.

[0027] (2) The preparation method of the three-dimensional self-supporting electrode of the present invention mainly involves dissolving resorcinol, formaldehyde and iron-containing compounds in the raw materials to form a precursor solution, and then synthesizing carbon-coated nano-Fe3O4 in situ in one step through hydrothermal reaction. This can effectively reduce the aggregation and accumulation of nano-Fe3O4 materials and improve the active sites and cycle stability of the electrode material.

[0028] (3) The preparation method of the three-dimensional self-supporting electrode of the present invention has readily available raw materials, simple preparation process, high preparation efficiency, low cost, and can be used for large-scale production. It has broad application prospects in the field of lithium-ion battery electrodes.

[0029] (4) The three-dimensional self-supporting electrode of the present invention has an in-situ carbon-coated nano Fe3O4 particle structure that can effectively buffer the volume change and electrochemical impact of nano Fe3O4 during lithium ion insertion and extraction; and the porous structure on the nickel foam substrate of the three-dimensional self-supporting electrode can also help suppress the irreversible volume expansion problem of Fe3O4 during charging and discharging.

[0030] (5) The three-dimensional self-supporting electrode of the present invention, due to its electrode structure without conductive agent or binder, can increase the energy density of the whole cell. Furthermore, due to the stronger and more uniform bonding force between the active material and the current collector, and the absence of dead volume, the utilization efficiency of the active material can be further improved, and the electron mobility is higher.

[0031] (6) The three-dimensional self-supporting electrode of the present invention can increase the contact area between the active material and the electrolyte, which is beneficial to ion transport, shortens the ion diffusion path, and improves rate performance and cycle performance. Attached Figure Description

[0032] Figure 1 The X-ray diffraction patterns are those of the three-dimensional self-supporting electrode material with in-situ carbon-coated nano-Fe3O4 obtained in Example 2 of the present invention, the Fe3O4 self-supporting electrode material obtained in Comparative Example 1, and the electrode material prepared by carbon-coated Fe3O4 coating obtained in Comparative Example 2.

[0033] Figure 2 This is a scanning electron microscope (SEM) image of the three-dimensional self-supporting electrode material with in-situ carbon-coated nano-Fe3O4 obtained in Example 2 of the present invention.

[0034] Figure 3 This is a TEM image of the three-dimensional self-supporting electrode material with in-situ carbon-coated nano-Fe3O4 obtained in Example 2 of the present invention.

[0035] Figure 4 The graph shows a comparison of the rate performance curves of the three-dimensional self-supporting electrode material with in-situ carbon-coated nano-Fe3O4 obtained in Examples 1-3 of the present invention and the Fe3O4 self-supporting electrode material obtained in Comparative Example 1 as a negative electrode material for lithium-ion batteries.

[0036] Figure 5 The three-dimensional self-supporting electrode material with in-situ carbon-coated nano-Fe3O4 obtained in Example 2 of the present invention and the Fe3O4 self-supporting electrode material obtained in Comparative Example 1 are used as anode materials for lithium-ion batteries at 5Ag. -1 Performance comparison chart of high current cyclic charge and discharge cycles of 1000 times.

[0037] Figure 6 The three-dimensional self-supporting electrode material with in-situ carbon-coated nano-Fe3O4 obtained in Example 2 of the present invention and the electrode material prepared by carbon-coated Fe3O4 coating obtained in Comparative Example 2 are used as lithium-ion battery anode materials at 1A g. -1 Performance comparison chart of high current cyclic charge and discharge 200 times.

[0038] Figure 7 The three-dimensional self-supporting electrode material with in-situ carbon-coated nano-Fe3O4 obtained in Example 2 of this invention was used as the negative electrode material of a lithium-ion battery, and lithium iron phosphate was used as the positive electrode material. The resulting full cell was prepared in 0.1 Ag... -1 Performance comparison chart after 500 cycles at current density. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0040] Example 1

[0041] The method for fabricating the three-dimensional self-supporting electrode in this embodiment includes the following steps:

[0042] (1) Cut the foamed Ni sheet into 3*5cm size, then soak it in 3M hydrochloric acid for 30min, take it out and ultrasonically clean it three times in deionized water and ethanol respectively, and then dry it in a 60℃ oven to obtain a clean foamed Ni conductive substrate after activation.

[0043] (2) Dissolve 0.1g and 0.2ml of resorcinol and formaldehyde in 60ml of ethanol and aqueous solution with a volume ratio of 1:2, and add 0.3ml of ammonia water. Stir for 30min to mix thoroughly.

[0044] (3) Add 1.5g of ferric nitrate nonahydrate to step (2) and continue stirring for 30min. Transfer the solution to a 100ml reaction vessel and place the foamed Ni sheet treated in step (1) into the vessel at a 45° angle. The hydrothermal temperature is 180℃ and the reaction time is 12h. After natural cooling, dry in a 60℃ oven to obtain foamed Ni sheet containing iron-carbon precursor.

[0045] (4) The foamed Ni sheet containing iron-carbon precursor obtained in step (3) is annealed at 600°C for 2 hours in N2 atmosphere with a heating rate of 5°C / min. After natural cooling to room temperature, a three-dimensional self-supporting electrode material with in-situ carbon-coated nano Fe3O4 is obtained.

[0046] Example 2

[0047] The method for fabricating the three-dimensional self-supporting electrode in this embodiment includes the following steps:

[0048] (1) Cut the foamed Ni sheet into 3*5cm size, then soak it in 3M hydrochloric acid for 30min, take it out and ultrasonically clean it three times in deionized water and ethanol respectively, and then dry it in a 60℃ oven to obtain a clean foamed Ni conductive substrate after activation.

[0049] (2) Dissolve 0.1g and 0.2ml of resorcinol and formaldehyde in 60ml of ethanol and aqueous solution with a volume ratio of 1:2, and add 0.3ml of ammonia water. Stir for 30min to mix thoroughly.

[0050] (3) Add 2.0g of ferric nitrate nonahydrate to step (2) and continue stirring for 30min. Transfer the solution to a 100ml reaction vessel and place the foamed Ni sheet treated in step (1) into the vessel at a 45° angle. The hydrothermal temperature is 180℃ and the reaction time is 12h. After natural cooling, dry in a 60℃ oven to obtain foamed Ni sheet containing iron-carbon precursor.

[0051] (4) The foamed Ni sheet containing iron-carbon precursor obtained in step (3) is annealed at 600°C for 2 hours in N2 atmosphere with a heating rate of 5°C / min. After natural cooling to room temperature, a three-dimensional self-supporting electrode material with in-situ carbon-coated nano Fe3O4 is obtained.

[0052] Example 3

[0053] (1) Cut the foamed Ni sheet into 3*5cm size, then soak it in 3M hydrochloric acid for 30min, take it out and ultrasonically clean it three times in deionized water and ethanol respectively, and then dry it in a 60℃ oven to obtain a clean foamed Ni conductive substrate after activation.

[0054] (2) Dissolve 0.1g and 0.2ml of resorcinol and formaldehyde in 60ml of ethanol and aqueous solution with a volume ratio of 1:2, and add 0.3ml of ammonia water. Stir for 30min to mix thoroughly.

[0055] (3) Add 2.5g of ferric nitrate nonahydrate to step (2) and continue stirring for 30min. Transfer the solution to a 100ml reaction vessel and place the foamed Ni sheet treated in step (1) into the vessel at a 45° angle. The hydrothermal temperature is 180℃ and the reaction time is 12h. After natural cooling, dry in a 60℃ oven to obtain foamed Ni sheet containing iron-carbon precursor.

[0056] (4) The foamed Ni sheet containing iron-carbon precursor obtained in step (3) is annealed at 600°C for 2 hours in N2 atmosphere with a heating rate of 5°C / min. After natural cooling to room temperature, a three-dimensional self-supporting electrode material with in-situ carbon-coated nano Fe3O4 is obtained.

[0057] Comparative Example 1

[0058] This comparative example demonstrates the in-situ growth of nano-Fe3O4 three-dimensional self-supporting electrode material directly on the treated Ni foam sheet. The specific steps are as follows:

[0059] (1) Cut the foamed Ni sheet into 3*5cm size, then soak it in 3M hydrochloric acid for 30min, take it out and ultrasonically clean it three times in deionized water and ethanol respectively, and then dry it in a 60℃ oven to obtain a clean foamed Ni conductive substrate after activation.

[0060] (2) Add 0.3 ml of ammonia water to 60 ml of ethylene glycol solution and stir for 30 min to mix thoroughly.

[0061] (3) Add 2.0g of ferric nitrate nonahydrate to step (2) and continue stirring for 30min. Transfer the solution to a 100ml reaction vessel and place the foamed Ni sheet treated in step (1) into the vessel at a 45° angle. The hydrothermal temperature is 180℃ and the reaction time is 12h. After natural cooling, dry in a 60℃ oven to obtain foamed Ni sheet containing iron precursor.

[0062] (4) The foamed Ni sheet containing iron precursor obtained in step (3) is annealed in N2 atmosphere at 600°C for 2 hours with a heating rate of 5°C / min. After natural cooling to room temperature, a three-dimensional self-supporting electrode material loaded with nano Fe3O4 can be obtained.

[0063] Comparative Example 2

[0064] In this comparative example, in-situ carbon-coated nano-Fe3O4 was first prepared, and then coated onto copper foil. The specific steps are as follows:

[0065] (1) Dissolve 0.1g and 0.2ml of resorcinol and formaldehyde in 60ml of ethanol and aqueous solution with a volume ratio of 1:2, and add 0.3ml of ammonia water. Stir for 30min to mix thoroughly.

[0066] (2) Add 2.0g of ferric nitrate nonahydrate to step (2) and continue stirring for 30min. Transfer the solution to a 100ml reaction vessel. The hydrothermal temperature is 180℃ and the reaction time is 12h. After natural cooling, an iron-carbon precursor is obtained. Take out the precipitate and wash it several times with ethanol and deionized water.

[0067] (3) The iron-carbon precursor powder sample obtained in step (2) is annealed at 600°C for 2 hours in N2 atmosphere with a heating rate of 5°C / min. After natural cooling to room temperature, the powder electrode material loaded with in-situ carbon-coated nano-Fe3O4 is obtained.

[0068] (4) The powder electrode material with in-situ carbon-coated nano Fe3O4 obtained in step (3) is mixed with conductive agent (acetylene black) and binder PVDF (polyvinylidene fluoride) at a mass ratio of 8:1:1. The mixture is ground into a slurry using NMP (N-methyl-2-pyrrolidone) solvent. The slurry is then uniformly coated on a single-sided copper foil and dried in a vacuum oven at 100°C for 10 hours to obtain the electrode material.

[0069] The three-dimensional self-supporting electrode with in-situ carbon-coated nano-Fe3O4 obtained in Example 2 of the present invention (Fe3O4@C_self-supporting), the three-dimensional self-supporting electrode material of Fe3O4 obtained in Comparative Example 1 (Fe3O4_self-supporting), and the material of Comparative Example 2 (Fe3O4@C4_coating) were characterized by XRD. Figure 1 It can be seen that the XRD diffraction patterns of the samples in Example 2, Comparative Examples 1 and 2 all correspond to the Fe3O4 (PDF#77-1545) standard card, indicating that Fe3O4 phase was generated in all samples and no other impurity phases were generated.

[0070] Figure 2 This is a scanning electron microscope (SEM) image of the three-dimensional self-supporting electrode material with in-situ carbon-coated nano-Fe3O4 obtained in Example 2 of the present invention. As shown in the figure, the Fe3O4 material obtained in Example 1 has a nanometer-scale particle size and exhibits a nanosphere morphology. The surface of the nanospheres is covered with an amorphous carbon layer that cross-links them together.

[0071] Figure 3 This is a TEM image of the three-dimensional self-supporting electrode material of Fe3O4 nanoparticles loaded with in-situ carbon prepared in Example 2 of the present invention. As shown in the figure, the prepared Fe3O4 electrode material is in the form of nanospheres, and the surface of the Fe3O4 nanoparticles is coated with an amorphous carbon layer. In addition, the 0.25 nm interplanar spacing in the figure belongs to the (311) crystal plane of Fe3O4. All the above results indicate that the three-dimensional self-supporting electrode material of Fe3O4 nanoparticles loaded with in-situ carbon was successfully synthesized.

[0072] The in-situ carbon-coated nano-Fe3O4 three-dimensional self-supporting electrode materials prepared in Examples 1-3 and the electrode materials prepared in Comparative Examples 1 and 2 were used as negative electrodes to prepare lithium-ion batteries, and their electrochemical performance was analyzed. The obtained electrode materials were cut into electrode sheets with a diameter of 0.7 × 0.7 cm. In an argon-filled glove box, lithium metal sheets or commercially available LiFePO4 (LFP) were used as positive electrodes, with a Kroeder 2500 separator and a 1M LiPF6 solution as the electrolyte. The electrodes were arranged in the following order: negative electrode shell - spring sheet - gasket - lithium sheet - separator - negative electrode - positive electrode shell. The battery was then sealed using a manual hydraulic sealer under a pressure of 50 MPa, assembling a CR2032 coin cell. Electrochemical performance was tested using a Newway battery tester.

[0073] The rate performance of the prepared lithium-ion battery was tested by... Figure 4 It can be seen that the rate performance of the in-situ carbon-coated nano-Fe3O4 three-dimensional self-supporting electrode material prepared in Example 2 (Fe3O4@C_2) is better than that of Example 1 (Fe3O4@C_1), Example 3 (Fe3O4@C_3), and Comparative Example 1 (Fe3O4_1). This indicates that when the mass ratio of ferric nitrate nonahydrate to resorcinol is 2.0:0.1, the prepared sample has better charge transport rate and lithium ion diffusion rate.

[0074] At room temperature, the electrode materials of Example 2 and Comparative Example 1 were subjected to multiple charge-discharge cycle tests at different current densities between 0.01 and 3.0 V. Figure 5 It can be seen that the in-situ carbon-coated nano-Fe3O4 three-dimensional self-supporting electrode material (Fe3O4@C) obtained in Example 2 still retains 87% of its performance after 1000 cycles at a current density of 5 A / g, while the Fe3O4 three-dimensional self-supporting electrode material obtained in Comparative Example 1 only retains 3%. This means that the electrode material (Fe3O4) in Comparative Example 1 is almost completely destroyed during the high current density cyclic charge-discharge process. This also shows that the in-situ carbon-coated nano-Fe3O4 three-dimensional self-supporting electrode prepared in Example 1 can effectively suppress the irreversible volume expansion of Fe3O4 active material during high current charge-discharge, giving it excellent electrochemical stability.

[0075] Depend on Figure 6 It can be seen that the in-situ carbon-coated nano-Fe3O4 three-dimensional self-supporting electrode material obtained in Example 2 (foamed nickel) still basically maintains its initial specific capacity performance after 200 cycles at a current density of 1 A / g, while the electrode material (copper foil) prepared by carbon-coated Fe3O4 coating obtained in Comparative Example 2 only retains about 31% of its specific capacity. This indicates that the porous structure on the three-dimensional self-supporting electrode foamed nickel substrate used in Example 2 helps to suppress the problem of irreversible volume expansion of Fe3O4 during charging and discharging, and improves the cycle stability of the electrode material.

[0076] To better evaluate the commercial application prospects of the in-situ carbon-coated nano-Fe3O4 three-dimensional self-supporting electrode material prepared in Example 2, lithium-ion full cells were assembled using the three-dimensional self-supporting electrode prepared in Example 2 and commercial LiFePO4 (LFP) as the negative and positive electrodes, respectively. Figure 7 As shown, the lithium-ion full battery exhibits almost no capacity decay after 500 cycles at a current density of 0.1 A / g, demonstrating its excellent electrochemical performance and facilitating large-scale commercial applications.

[0077] In the above embodiments, ferric nitrate nonahydrate can also be replaced with one of ferric chloride, ferric sulfate, and ferric citrate.

[0078] In the above embodiments, the three-dimensional conductive substrate foam Ni can also be replaced with foam Cu or activated carbon cloth.

[0079] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for the preparation of a three-dimensional self-supporting electrode, characterized in that, The method comprises the following steps: resorcinol and formaldehyde are dissolved in a mixed solution of ethanol and water, and ammonia water is added, and stirring is performed until they are fully mixed to obtain an organic polymer solution; an iron-containing compound is added to the organic polymer solution, and stirring is performed until it is fully dissolved to obtain a precursor solution; the precursor solution is transferred to a reaction kettle, a three-dimensional conductive substrate is placed in the reaction kettle for hydrothermal reaction to obtain a three-dimensional self-supporting substrate containing an iron / carbon precursor; the iron-containing compound is at least one of ferric chloride, ferric nitrate nonahydrate, ferric sulfate, and ferric citrate; the three-dimensional self-supporting substrate containing the iron / carbon precursor is dried and then annealed in an inert atmosphere, and after natural cooling to room temperature, a three-dimensional self-supporting electrode loaded with in-situ carbon-coated nano-Fe3O4 is obtained.

2. The method of claim 1, wherein the three-dimensional self-supporting electrode is prepared by a method comprising: The three-dimensional conductive substrate is a foam Ni, a foam Cu, or an activated carbon cloth.

3. The method of claim 1, wherein the three-dimensional self-supporting electrode is prepared by a method comprising: The mass / volume ratio of the resorcinol and the formaldehyde is (1-5) g:(1-4) ml.

4. The method of claim 1, wherein the three-dimensional self-supporting electrode is prepared by a method comprising: The mass ratio of the iron-containing compound to the resorcinol is (1.5-2.5):0.

1.

5. The method of claim 1, wherein the three-dimensional self-supporting electrode is prepared by a method comprising: The reaction conditions of the hydrothermal reaction are as follows: the reaction temperature is 160-200℃, and the reaction time is 8-12 h.

6. The method of claim 1, wherein the three-dimensional self-supporting electrode is prepared by a method comprising: The annealing treatment is specifically as follows: the annealing treatment temperature is 400-800℃, the annealing treatment time is 1-3 h, and the heating rate is 5-10℃ / min.

7. The method of claim 1, wherein the three-dimensional self-supporting electrode is prepared by a method comprising: The inert atmosphere is at least one of N2 and Ar.

8. The method of claim 1, wherein the three-dimensional self-supporting electrode is prepared by, The three-dimensional conductive substrate is placed in the reaction kettle and is arranged to form an angle of 40-50° with the liquid surface of the precursor solution. The three-dimensional self-supporting electrode is prepared by the preparation method of any one of claims 1-8.

9. A three-dimensional self-supporting electrode, characterized by The three-dimensional self-supporting electrode of claim 9 is used as a negative electrode.

10. A lithium-ion battery, characterized by, ​

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