Electrode and preparation method therefor, and solid-state battery

Abstract

An electrode and a preparation method therefor, and a solid-state battery. The electrode comprises a current collector and a carbon nanotube layer that covers the current collector, wherein a catalyst is distributed at the bottoms and tops of carbon nanotubes. When the electrode is applied to a battery, the catalyst distributed at the bottoms and tops of the carbon nanotubes can synergistically induce the uniform deposition of lithium metal, and when lithium ions are uniformly distributed on the surface of the electrode and in the electrode, the situation of an excessively high local lithium-ion concentration does not occur, and the uniform deposition can avoid the generation of local overpotential, thereby preventing lithium plating; moreover, by designing and controlling the deposition amount of lithium to not exceed the maximum in-tube and inter-tube deposition capacity of the carbon nanotubes, the whole electrode is free from expansion and shrinkage during charging and discharging, thereby effectively limiting the expansion of lithium metal.

Description

Electrodes and their preparation methods and solid-state batteries

[0001] This application claims priority to Chinese Patent Application No. CN202411606613.X, filed on November 12, 2024, entitled "Electrode and Preparation Method Thereof and Solid-State Battery", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of battery technology, and in particular to an electrode, its preparation method, and a solid-state battery. Background Technology

[0003] Traditional liquid batteries, as the current mainstream energy storage device, have relatively mature internal structures and working principles. However, liquid batteries have inherent limitations in terms of energy density and cycle life, mainly due to the incompatibility between liquid electrolytes and lithium metal anodes. Specifically, liquid electrolytes are chemically difficult to coexist stably with lithium metal, leading to rapid performance degradation during charge-discharge cycles, severely limiting the application of lithium metal anodes in liquid batteries. Lithium metal, as a high-energy-density anode material, boasts a theoretical energy density of up to 3860 mAh / g, far exceeding other existing anode materials. Therefore, effectively utilizing lithium metal anodes would significantly improve battery energy density and range.

[0004] To overcome this bottleneck in liquid batteries, researchers began exploring all-solid-state battery technology. The core innovation of all-solid-state batteries lies in using a solid electrolyte instead of the traditional liquid electrolyte and polymer separator. Solid electrolytes, due to their unique wide voltage window characteristics (the wide voltage window characteristic refers to the ability of a solid electrolyte to remain stable over a large voltage range without decomposition or significant performance degradation; the window refers to the voltage range within which the electrolyte can operate safely and effectively), successfully solved the incompatibility problem between liquid electrolytes and lithium metal, making the application of lithium metal anodes in all-solid-state batteries possible. This breakthrough has opened up new avenues for improving battery energy density and is expected to drive a qualitative leap in battery technology.

[0005] However, in the commercial application of all-solid-state battery technology, although solid electrolytes enable the use of lithium metal anodes, the extremely high volume expansion rate of lithium metal during charge and discharge has become a key factor restricting the performance and lifespan of all-solid-state batteries. The high energy density of lithium metal is accompanied by significant volume changes, which not only leads to drastic fluctuations in the overall battery volume but may also cause deterioration of the electrolyte-lithium metal interface structure, thus severely affecting the battery's cycle stability and lifespan. Therefore, in the design of high-energy-density solid-state batteries, how to effectively limit the expansion of lithium metal through electrodes has become a core technical challenge that urgently needs to be solved. Technical issues

[0006] The main objective of this application is to provide an electrode, its preparation method, and a solid-state battery, aiming to solve the technical problem of how to effectively limit the expansion of lithium metal through electrodes in existing high-energy-density solid-state battery designs. Technical solutions

[0007] The main objective of this invention is to provide an electrode, its preparation method, and a solid-state battery, aiming to solve the technical problem of how to effectively limit the expansion of lithium metal through electrodes in existing high-energy-density solid-state battery designs.

[0008] To achieve the above objectives, a first aspect of the present invention provides an electrode comprising a current collector and a carbon nanotube layer covering the current collector, wherein a catalyst is distributed at the bottom and top of the carbon nanotubes.

[0009] Furthermore, the current collector is made of metal.

[0010] Furthermore, the catalyst comprises one or more selected from silver and silver-containing complexes.

[0011] Furthermore, the carbon nanotubes are one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, and modified carbon nanotubes.

[0012] A second aspect of the present invention provides a method for preparing an electrode, comprising the following steps:

[0013] S1: Coating the current collector with catalyst;

[0014] S2: Place the coated current collector in a fluidized bed for fluidization;

[0015] S3: A carbon source is introduced into a fluidized bed to grow carbon nanotubes by chemical vapor deposition, thereby fabricating the electrode.

[0016] Furthermore, the carbon source is one or more combinations of carbon monoxide, carbon dioxide, ethylene, acetylene, methane, and propylene gas.

[0017] Furthermore, the chemical vapor deposition method is either direct current electrodeposition or pulsed electrodeposition.

[0018] A third aspect of the present invention provides a solid-state battery comprising the electrode described in any of the preceding claims as a negative electrode.

[0019] Furthermore, the electrolyte of the solid-state battery is a solid electrolyte.

[0020] Furthermore, the negative electrode also includes a negative electrode active material, which is lithium metal. Beneficial effects

[0021] Compared with existing technologies, the electrode of the present invention includes a current collector and a carbon nanotube layer covering the current collector, wherein a catalyst is distributed at the bottom and top of the carbon nanotubes. When the electrode of this technical solution is applied to a battery, because the catalyst is at the bottom and top of the carbon nanotubes, it can synergistically induce lithium metal to be uniformly deposited on the surface and bottom of the carbon nanotube electrode. When lithium ions are uniformly distributed on the electrode surface and inside (inside and between the carbon nanotubes), there will be no situation where the local lithium ion concentration is too high. During lithium-ion charging, lithium ions need to overcome a certain potential difference to be deposited on the negative electrode. If lithium ions are not uniformly deposited, the lithium ion concentration in a local area will be too high, which will lead to an excessive potential difference in that area, i.e., local overpotential. Local overpotential will cause lithium ions to be over-deposited in that area, forming metallic lithium precipitation, i.e., lithium plating. Uniform deposition can avoid the generation of local overpotential, thereby preventing lithium plating. At the same time, by designing and controlling the amount of lithium deposition to not exceed the maximum deposition capacity inside and between the carbon nanotubes, the entire electrode does not expand or contract during charging and discharging, effectively limiting the expansion of lithium metal.

[0022] Compared with existing technologies, the electrode preparation method of this application involves coating a catalyst onto a current collector and then growing carbon nanotubes in a fluidized bed using chemical vapor deposition. During fluidization, the catalyst migrates to some extent with the gas flow and reaction, resulting in a distribution of the catalyst on both the surface of the current collector (bottom of the carbon nanotubes) and the top of the growing carbon nanotubes. During carbon nanotube growth, some carbon nanotubes begin to grow from the surface of the current collector. The catalyst on the surface of the current collector serves as the starting point for the reaction, guiding the decomposition of the carbon source gas to form carbon nanotubes. As the carbon nanotubes grow on the surface of the current collector, a portion of them... The carbon nanotubes are grown inside the current collector to firmly adhere to it, eliminating the need for additional binders, further reducing material usage and lowering costs. Simultaneously, some carbon nanotubes grow through the catalyst on top, resulting in the catalyst also appearing on top of the carbon nanotubes (electrode surface) to form the electrode. This method eliminates traditional stirring and coating processes, reducing costs. Furthermore, during electrode fabrication, the length of the carbon nanotubes can be adjusted by regulating the vapor deposition time, and the density of the carbon nanotubes can be adjusted by regulating the catalyst coating density, allowing for flexible design of batteries with various energy densities and thicknesses.

[0023] Compared with the prior art, the solid-state battery of this application includes the electrodes described above. It is understood that the solid-state battery of this application can possess all the technical features and beneficial effects of the electrodes described above, which will not be elaborated further here. Attached Figure Description

[0024] Figure 1 is a schematic diagram of a copper foil current collector with a silver catalyst on its surface in Embodiment 1 of the present invention;

[0025] Figure 2 is a schematic diagram of in-situ generation of carbon nanotubes in Embodiment 1 of the present invention;

[0026] Figure 3 is a schematic diagram of the state of the in-situ grown carbon nanotube negative electrode after lithium intercalation in Embodiment 1 of the present invention;

[0027] Figure 4 is a flowchart of the preparation process of the in-situ grown electrode in Embodiment 1 of the present invention.

[0028] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. The best embodiment of the present invention

[0029] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0030] Please refer to Figures 1 to 3. One embodiment of the present invention provides an electrode, including a current collector and a carbon nanotube layer covering the current collector. The bottom and top of the carbon nanotubes are distributed with catalysts, and the current collector is made of a metal material.

[0031] In this embodiment, the current collector acts as a support. A carbon nanotube layer covers the current collector, and catalysts are distributed at the bottom (the portion in contact with the current collector) and top of the carbon nanotubes to induce lithium-ion deposition. The current collector is made of a metallic material with good conductivity and mechanical properties, providing a stable electron transport channel and physical support for the electrode. Exemplarily, it can be copper foil or aluminum foil; copper foil is preferred in this application. In this application, the electrode is prepared by in-situ growth. In-situ growth refers to the process where reactants directly react in situ on a specific substrate surface to generate the target product.

[0032] It should be noted that during lithium-ion charging, lithium ions need to overcome a certain potential difference to deposit on the negative electrode. If lithium ions are not deposited uniformly, the lithium ion concentration in local areas will be too high, leading to an excessively large potential difference in those areas, i.e., local overpotential. Local overpotential will cause excessive deposition of lithium ions in that area, resulting in the precipitation of metallic lithium, also known as lithium plating. In this application, the bottom and top of the carbon nanotubes are the opposite ends of the carbon nanotubes relative to their arrangement or growth direction on the current collector. The bottom refers to the part of the carbon nanotube that is in direct contact with or close to the current collector, while the top refers to the part of the carbon nanotube that is away from the current collector and extends or protrudes.

[0033] In the above embodiments, when the electrode is applied to a battery, since the catalyst is at the bottom and top of the carbon nanotube, it can synergistically induce lithium ions to be uniformly deposited on the surface and bottom of the carbon nanotube electrode. When lithium ions are uniformly distributed on the electrode surface and inside (inside and between the carbon nanotubes), there will be no local lithium ion concentration that is too high. Uniform deposition can avoid the generation of local overpotential, thereby preventing lithium plating. At the same time, by designing and controlling the amount of lithium deposition to not exceed the maximum deposition capacity inside and between the carbon nanotubes, the entire electrode does not expand or contract during charging and discharging, effectively limiting the expansion of lithium metal.

[0034] In one embodiment, the catalyst comprises one or more selected from silver and silver-containing complexes.

[0035] In this embodiment, silver exhibits excellent catalytic activity, effectively reducing the activation energy of the reaction and promoting the growth of carbon nanotubes. Its high chemical stability prevents chemical reactions under battery operating conditions (such as contact with solid electrolytes and during charge / discharge processes), ensuring stable performance and continuous catalytic activity. Simultaneously, silver guides lithium-ion deposition, enabling uniform deposition of lithium ions on the surface and bottom of the carbon nanotube anode, avoiding lithium plating. Iron possesses multiple valence states, allowing it to participate in various redox reactions to promote carbon nanotube growth. For example, in chemical vapor deposition, iron can regulate the reaction process by changing its valence state. While iron is relatively inexpensive, its chemical stability is lower than silver, making it prone to oxidation and other reactions. Therefore, to compensate for the shortcomings of iron catalysts and reduce the cost of silver catalysts, the silver-containing composite in this application can be a silver-based iron catalyst. Cobalt possesses a unique electronic structure, enabling it to provide active sites in catalytic reactions and promote carbon nanotube growth. Cobalt can form specific adsorption states with carbon source gases, facilitating the decomposition of gas molecules and the formation of carbon nanotubes. In battery applications, cobalt can improve the electrochemical performance of electrodes to a certain extent, enhancing their conductivity and ion transport capabilities. However, cobalt resources are relatively scarce and expensive, and its cost is higher than that of silver when used alone. To reduce the cost of the catalyst, the silver-containing composite of this application can also be a silver-based cobalt catalyst. Nickel is a common catalyst that can accelerate the chemical reactions during the growth of carbon nanotubes. The catalytic activity of nickel stems from the electronic structure and chemisorption characteristics of its surface atoms; it can adsorb carbon source gases and promote their decomposition. In battery electrodes, nickel helps improve the structural stability and conductivity of the electrode. However, nickel may undergo corrosion and other reactions in certain electrolyte environments, affecting its long-term stability. Therefore, to ensure the stability of the catalyst, the silver-containing composite of this application can also be a silver-based nickel catalyst. Since the silver-containing composite catalyst is compatible with some of the defects of its composite material compared to the silver catalyst, silver is preferred as the catalyst in this application.

[0036] In one embodiment, the carbon nanotube is one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, and modified carbon nanotubes.

[0037] In this embodiment, single-walled carbon nanotubes are seamless tubular structures formed by rolling up a single layer of graphene sheet; multi-walled carbon nanotubes are composed of multiple concentric nested graphene tubes; modified carbon nanotubes are obtained by chemically or physically treating ordinary carbon nanotubes to introduce specific functional groups or change their surface properties. For example, hydroxyl, carboxyl, and other functional groups can be introduced onto the surface of carbon nanotubes through surface oxidation treatment, or the electronic structure and properties of carbon nanotubes can be changed by doping with other elements. In the preparation of the in-situ grown electrode, one or more combinations of single-walled carbon nanotubes, multi-walled carbon nanotubes, and modified carbon nanotubes can be selected. Different types of carbon nanotubes can exert synergistic effects.

[0038] In the above embodiments, during the electrode preparation step, when a carbon source is introduced into the fluidized bed, the mixed growth of different carbon nanotubes can be achieved by controlling the type and sequence of the carbon source. First, a carbon source gas favorable for the growth of single-walled carbon nanotubes is introduced, and after a certain time, a carbon source suitable for the growth of multi-walled carbon nanotubes is introduced. Simultaneously, gases or precursors that can modify the carbon nanotubes are added, thereby achieving a combination of multiple carbon nanotubes during in-situ growth.

[0039] Referring to Figure 4 and in conjunction with Figures 1 to 3, another embodiment of the present invention provides a method for preparing an electrode, which includes the following steps:

[0040] S1: Coating the catalyst onto the metal current collector;

[0041] S2: Place the coated current collector in a fluidized bed for fluidization;

[0042] S3: A carbon source is introduced into a fluidized bed to grow carbon nanotubes by chemical vapor deposition, thereby fabricating the electrode.

[0043] In this embodiment, the metal material serves as the current collector for the electrode, providing physical support for the subsequent growth of carbon nanotubes. The catalyst is a key factor in carbon nanotube growth, guiding the growth process. Through a coating process, the catalyst is uniformly distributed on the surface of the metal current collector, providing active sites for the subsequent chemical vapor deposition reaction. Depending on the properties of the selected catalyst, such as silver, iron, cobalt, or nickel, these metals possess catalytic activity and can lower the activation energy of the carbon nanotube growth reaction. For example, the surface of silver can adsorb carbon source gas molecules; when the catalyst is coated onto the metal current collector, its surface active sites can interact with the carbon source gas that is about to be introduced.

[0044] In the above embodiments, the main purpose of fluidization is to ensure that the catalyst-coated current collector is in a good reaction state. A fluidized bed allows catalyst particles to be suspended in the gas flow, ensuring sufficient contact between the current collector and the reactant gas. This ensures a more uniform reaction between the catalyst and the carbon source gas when it is subsequently introduced, avoiding excessively vigorous or incomplete reactions in certain areas. Simultaneously, during catalyst fluidization, the catalyst migrates to some extent with the gas flow and the progress of the reaction, resulting in a distribution of catalyst on both the surface of the current collector (bottom of the carbon nanotubes) and the top of the growing carbon nanotubes, as shown in Figure 2. During carbon nanotube growth, some carbon nanotubes begin to grow from the surface of the current collector, with the catalyst serving as the starting point for the reaction, guiding the decomposition of the carbon source gas and the formation of carbon nanotubes. Simultaneously, some carbon nanotubes grow through the catalyst at the top, resulting in the catalyst also appearing on the top of the carbon nanotubes (electrode surface), thus creating an in-situ grown electrode.

[0045] It should be noted that Figure 2 of this application only shows the growth of carbon nanotubes on one side of the current collector. It is understood that carbon nanotubes can also grow on the other side at the same time.

[0046] In the above embodiments, carbon nanotubes are grown on a catalyst-coated current collector by introducing a carbon source gas, thereby forming an electrode with carbon nanotubes. The growth of carbon nanotubes can increase the specific surface area of ​​the electrode, improve its conductivity and ion transport performance, etc. When a carbon source gas (such as one or more combinations of carbon monoxide, carbon dioxide, ethylene, acetylene, methane, and propylene) is introduced into a fluidized bed, a decomposition reaction occurs under the action of a catalyst. Taking ethylene as an example, under the catalysis of catalysts such as silver, silver-based iron, silver-based cobalt, and silver-based nickel, the carbon-carbon double bonds in the ethylene molecule break, and carbon atoms aggregate on the catalyst surface and gradually grow to form carbon nanotubes. According to the principle of chemical vapor deposition, during the reaction process, the carbon source gas continuously decomposes, and carbon atoms are orderly arranged and grown under the guidance of the catalyst, ultimately forming a carbon nanotube layer on the current collector, thus fabricating the electrode.

[0047] In one embodiment, the carbon source is one or more combinations of carbon monoxide, carbon dioxide, ethylene, acetylene, methane, and propylene gas.

[0048] In this embodiment, carbon monoxide is a gas with strong reducing properties. During chemical vapor deposition (CVD), the carbon-oxygen bonds in carbon monoxide molecules can break under the action of a catalyst, and the carbon atoms are used to construct carbon nanotubes. Carbon monoxide is relatively reactive, and its reactivity allows it to participate in the growth reaction of carbon nanotubes under relatively low temperature and pressure conditions in the presence of suitable catalysts (such as silver, silver-based iron, silver-based cobalt, silver-based nickel, etc.). Carbon dioxide, as a carbon source, releases carbon atoms when reduced, which are then used for the growth of carbon nanotubes. Ethylene molecules contain carbon-carbon double bonds, and these unsaturated bonds are easily broken under the action of a catalyst. Ethylene is a relatively ideal carbon source, providing sufficient carbon atoms and exhibiting high reactivity, enabling efficient generation of carbon nanotubes in CVD. Its double bond structure allows it to decompose and recombine carbon atoms in a certain manner when interacting with a catalyst, which is beneficial for controlling the growth structure of carbon nanotubes, such as tube diameter and wall thickness. Acetylene is a highly reactive gas containing carbon-carbon triple bonds. Acetylene has a relatively low carbon-carbon triple bond energy, making it easy to break on the catalyst surface and release carbon atoms. When used as a carbon source, acetylene can rapidly provide carbon atoms, which is beneficial for the rapid growth of carbon nanotubes. Furthermore, due to its high reactivity, under certain reaction conditions (such as high temperature and high catalyst activity), it can generate carbon nanotubes with special structures, such as those with high crystallinity or small diameter. Methane is the simplest organic compound, and its carbon-hydrogen single bond is relatively stable. However, under high temperature and the action of a catalyst, methane can undergo a decomposition reaction, releasing carbon atoms for carbon nanotube growth. Methane's advantages include its wide availability and low cost, making it a relatively economical carbon source choice. Propylene molecules contain a carbon-carbon double bond and a methyl group. This structural feature gives it both certain reactivity during the reaction process and the ability to provide relatively complex carbon structural units for carbon nanotube growth. Under the action of a catalyst, propylene can generate carbon nanotubes through various reaction pathways, which can have different effects on the structure and properties of the carbon nanotubes.

[0049] In one embodiment, the chemical deposition method is a direct current electrodeposition method or a pulse electrodeposition method, and this application does not impose any specific limitations.

[0050] Another embodiment of the present invention provides a solid-state battery, comprising an electrode prepared by the electrode preparation method described in any of the preceding claims as a negative electrode, wherein the electrolyte of the battery is a solid electrolyte. The negative electrode further comprises a negative electrode active material, wherein the negative electrode active material is metallic lithium.

[0051] In this embodiment, the present application preferably combines in-situ growth method to generate carbon nanotubes on the current collector as a support for the negative electrode catalyst. The catalyst uses elemental silver nanoparticles and / or silver-containing composites at the bottom and top of the carbon nanotubes, which can synergistically induce the uniform deposition of lithium ions on the surface and bottom of the carbon nanotube electrode. When lithium ions are uniformly distributed on the electrode surface and inside (inside and between the carbon nanotubes), there will be no local lithium ion concentration that is too high. Uniform deposition can avoid the generation of local overpotential, thereby preventing lithium plating. At the same time, by designing and controlling the amount of lithium deposition to not exceed the maximum deposition capacity inside and between the carbon nanotubes, the entire electrode does not expand or contract during charging and discharging, effectively limiting the expansion of lithium metal.

[0052] It should be noted that in-situ grown electrodes refer to electrodes prepared by directly growing electrode active materials with specific structures and functions on a substrate (such as a current collector) through a chemical reaction. The in-situ growth method used in this application for preparing carbon nanotubes is only a preferred embodiment. This application does not limit the use of other methods to prepare carbon nanotubes, as long as the bottom and top of the carbon nanotubes are distributed with catalyst after growth.

[0053] The preparation process and performance of the present invention will be illustrated below with some specific examples.

[0054] Example 1

[0055] 2g of silver was coated on the surface of copper foil as a catalyst, and 98g of arrayed carbon nanotubes with a length of 50um were grown by chemical vapor deposition to obtain an electrode of in-situ grown carbon nanotube / copper foil composite.

[0056] Example 2

[0057] In this embodiment, the only difference from Example 1 is that the length of the carbon nanotubes is 70 μm.

[0058] Example 3

[0059] In this embodiment, the only difference from Example 1 is that the catalyst is a silver-based iron catalyst.

[0060] Example 4

[0061] In this embodiment, the only difference from Example 1 is that the catalyst is a silver-based cobalt catalyst.

[0062] Example 5

[0063] In this embodiment, the only difference from Example 1 is that the catalyst is a silver-based nickel catalyst.

[0064] Comparative Example 1

[0065] Commercially available carbon nanotubes (80g) were used as the negative electrode active material. 14g of styrene-butadiene rubber and 6g of carboxymethyl cellulose were added and wet-mixed in water to obtain a slurry with a solid content of 20%. The slurry was then coated on the surface of copper foil and baked to form an electrode with a single-sided thickness of 50µm. The electrode was then obtained by rolling.

[0066] Comparative Example 2

[0067] In this comparative example, the only difference from Example 1 is that the catalyst is an iron catalyst.

[0068] Comparative Example 3

[0069] In this comparative example, the only difference from Example 1 is that the catalyst is a cobalt catalyst.

[0070] Comparative Example 4

[0071] In this comparative example, the only difference from Example 1 is that the catalyst is a nickel catalyst.

[0072] Comparative Example 5

[0073] In this comparative example, the difference from Example 1 is that the catalyst is only distributed at the bottom of the carbon nanotubes, and the catalyst is an iron catalyst.

[0074] The electrodes obtained in Examples 1-5 and the comparative example were assembled with ternary NCM811 (Nickel-Cobalt-Manganese: a ternary material system of nickel, cobalt, and manganese, where 811 represents the molar ratio of nickel, cobalt, and manganese of approximately 8:1:1) to form a solid-state battery. Energy density, 1C cycle life, and degradation tests were performed, and the battery was disassembled. The data obtained are shown in the table below:

[0075] Battery Sample Energy Density (Wh / kg) Maximum Discharge Power (W) in 10s 1C Cycle Decay Surface Lithium Plating Example 1 2 7 5 3 3 1 6 Cycles 6 12 Cycles Decay to 80% SOH No Example 2 2 8 2 3 2 1 3 Cycles 5 7 7 Cycles Decay to 80% SOH No Example 3 2 6 4 3 1 2 5 Cycles 5 5 7 Cycles Decay to 80% SOH No Example 4 2 5 8 3 0 1 7 Cycles 5 2 1 Cycles Decay to 80% SOH No Example 5 2 6 7 3 105 cycles, 496 rotations, decay to 80% SOH (No) Comparative Example 1: 1240 2850 cycles, 450 rotations, decay to 80% SOH (No) Comparative Example 2: 225 730 22 cycles, 541 rotations, decay to 80% SOH (No) Comparative Example 3: 25 230 14 cycles, 508 rotations, decay to 80% SOH (No) Comparative Example 4: 249 30 87 cycles, 489 rotations, decay to 80% SOH (No) Comparative Example 5: 25 429 78 cycles, 486 rotations, decay to 80% SOH (Yes)

[0076] The test results in the table above show that:

[0077] Compared to the comparative examples, after testing, Examples 1-5 of this application showed no lithium deposition on the surface of the battery negative electrode. This is because the negative electrode in this application has nano-silver catalysts and / or silver-containing complexes at both the bottom and top of the carbon nanotubes. Taking silver catalyst as an example, silver has specific chemical properties and surface energy, which can affect the lithium metal deposition process on both the surface and bottom of the carbon nanotube negative electrode. During battery charging, lithium metal ions need to be deposited on the negative electrode surface. The silver catalyst can provide suitable active sites. Since the silver catalyst exists at both the bottom and top of the carbon nanotubes, lithium metal ions can be uniformly reduced to lithium metal atoms at these sites, thereby achieving uniform deposition. Uniformly deposited lithium metal can prevent excessively high local lithium metal concentrations from causing lithium deposition.

[0078] The energy density of Example 2 of this application is higher than that of other examples and comparative examples. This is because the catalyst can reduce the energy barrier required for carbon nanotube growth, making the reaction easier and thus promoting the large-scale generation of carbon nanotubes. The larger carbon nanotubes have more conductive channels and active sites, which is beneficial for electron transport and lithium ion storage and diffusion, thereby improving the energy density of the battery. The catalyst can promote the uniform distribution of carbon nanotubes in the electrode and avoid the occurrence of agglomeration. The uniform electrode structure is conducive to the uniform distribution and transport of charge, improving the utilization rate of the electrode, thereby improving the energy density of the battery.

[0079] Compared to the comparative examples, the maximum discharge power of Examples 1-5 of this application is higher in 10s. This is because, during the preparation of the electrodes in this application, the density between carbon nanotubes can be adjusted through coating. Under fluidization, the carbon nanotubes are completely oriented, and their porosity can be adjusted. The carbon nanotubes of this application can provide a more favorable channel for the diffusion of lithium ions within the carbon nanotubes and the electrodes. During battery discharge, lithium ions can be more quickly deintercalated from the negative electrode and diffused to the positive electrode through the electrolyte. Rapid lithium ion diffusion can better coordinate with electron transport, maintaining the high speed of the electrode reaction. For example, during high-rate discharge (such as high-current discharge within 10s), lithium ions can be supplied to the reaction interface in a timely manner, accelerating the battery reaction rate and thus increasing the battery discharge power. Simultaneously, the carbon nanotube negative electrode with a catalyst can lower the activation energy of the electrode reaction. During battery discharge, electrode reactions (such as the transfer of electrons from lithium ion intercalation / deintercalation) need to overcome certain energy barriers to proceed. The presence of a catalyst can reduce this barrier, making the reaction easier to occur and accelerating the reaction rate. During a short discharge period of 10 seconds, this rapid reaction kinetics enables the battery to output more electrical energy per unit time, thereby increasing the maximum discharge power.

[0080] Examples 1-5 and Comparative Examples 2-4 of this application, compared with Comparative Examples 1 and 5, exhibit a greater number of cycles before decaying to 80% SOH in the 1C cycle test. This is because the catalyst, located at the bottom and top of the carbon nanotubes, promotes more uniform growth, narrower diameter distribution, and more suitable length of the carbon nanotubes. The uniform structure makes the conductive network formed by the carbon nanotubes in the negative electrode more stable and efficient. During cycling, it can better withstand the structural stress caused by lithium ion insertion and extraction, reducing local stress concentration and damage caused by structural inhomogeneity, thereby delaying battery performance decay and increasing the number of cycles.

[0081] Compared with Comparative Examples 2-4, Examples 3-5 showed no lithium deposition on the surface of the negative electrode after testing. This is because silver and silver-containing composites have high conductivity, which can provide a good electron transport environment for the growth of carbon nanotubes and promote the formation of carbon nanotubes. At the same time, silver has relatively stable chemical properties and is less likely to undergo side reactions during battery discharge, which can reduce the accumulation of lithium ions on the surface of the negative electrode. Therefore, no lithium deposition was found on the surface of the negative electrode.

[0082] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An electrode characterized by, It includes a current collector and a carbon nanotube layer covering the current collector, wherein a catalyst is distributed at the bottom and top of the carbon nanotubes.

2. The electrode of claim 1, wherein The catalyst comprises one or more selected from silver and silver-containing complexes.

3. The method of claim 1, wherein the step of applying the coating is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The carbon nanotubes are one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, and modified carbon nanotubes.

4. A method of producing an electrode, characterized by, The method for preparing the electrode as described in claim 1 includes the following steps: S1: Coating the current collector with catalyst; S2: Place the coated current collector in a fluidized bed for fluidization; S3: A carbon source is introduced into a fluidized bed to grow carbon nanotubes by chemical vapor deposition, thereby fabricating the electrode.

5. A method of producing an electrode, characterized by, The method for preparing the electrode as described in claim 2 includes the following steps: S1: Coating the current collector with catalyst; S2: Place the coated current collector in a fluidized bed for fluidization; S3: A carbon source is introduced into a fluidized bed to grow carbon nanotubes by chemical vapor deposition, thereby fabricating the electrode.

6. A method of producing an electrode, characterized by, The method for preparing the electrode as described in claim 3 includes the following steps: S1: Coating the current collector with catalyst; S2: Place the coated current collector in a fluidized bed for fluidization; S3: A carbon source is introduced into a fluidized bed to grow carbon nanotubes by chemical vapor deposition, thereby fabricating the electrode.

7. The method of claim 4, wherein the step of applying the coating is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The carbon source is one or more combinations of carbon monoxide, carbon dioxide, ethylene, acetylene, methane, and propylene gas.

8. The method of producing an electrode according to claim 5, wherein The carbon source is one or more combinations of carbon monoxide, carbon dioxide, ethylene, acetylene, methane, and propylene gas.

9. The method of claim 6, wherein the electrode is prepared by a method comprising: The carbon source is one or more combinations of carbon monoxide, carbon dioxide, ethylene, acetylene, methane, and propylene gas.

10. The method of claim 7, wherein the electrode is prepared by a method comprising: The chemical vapor deposition method is either direct current electrodeposition or pulse electrodeposition.

11. A solid state battery, characterized by The electrode as described in claim 1 is included as the negative electrode.

12. A solid state battery, characterized by The electrode as described in claim 2 is included as the negative electrode.

13. A solid state battery, characterized by The electrode as described in claim 3 is used as the negative electrode.

14. The solid-state battery of claim 11, wherein, The electrolyte in the solid-state battery is a solid electrolyte.

15. The solid-state battery of claim 11, wherein, The negative electrode also includes a negative electrode active material, which is lithium metal.

Images