Zinc battery negative electrode material, preparation method thereof and zinc ion battery

Abstract

The application discloses a zinc battery negative electrode material, a preparation method thereof and a zinc ion battery. The zinc battery negative electrode material is a composite of a carbon base material and zinc nanoparticles; the carbon base material is a porous carbon material with through nano or sub-micron channels, the zinc nanoparticles are distributed in the channels of the carbon base material, the surface of the zinc nanoparticles is wrapped by a carbon network, and the carbon network anchors the zinc nanoparticles in the channels of the carbon base material. A pulse mode is adopted to alternately introduce zinc sources and carbon sources, and interval purging is performed after each introduction; in view of the unique physical and chemical characteristics of zinc, a synergistic process of "functional group guidance-pulse deposition-immediate anchoring" is designed, so that the deposition of zinc nanoparticles and the growth of the carbon network are alternately performed. The zinc battery negative electrode material can not only inhibit the growth of zinc particles in a long-term electrochemical cycle process, improve the utilization rate of zinc, but also reduce the direct contact area of zinc and electrolyte, and is helpful to inhibit the occurrence of side reactions such as hydrogen evolution.

Description

Technical Field

[0001] This invention relates to the field of zinc-ion battery technology, and more specifically to a zinc battery anode material, its preparation method, and a zinc-ion battery. Background Technology

[0002] Aqueous zinc-ion batteries have promising applications in large-scale energy storage due to their low cost, high safety, and high specific capacity. However, zinc anodes are prone to zinc dendrite formation and hydrogen evolution side reactions during charge and discharge, leading to a decline in battery cycle performance. To address these issues, researchers have nanoscaled zinc and confined it within porous carbon materials to reduce direct contact between zinc and the electrolyte. The larger the zinc particle size in aqueous zinc-ion batteries, the more susceptible the zinc anode is to failure due to dendrite growth, hydrogen evolution side reactions, and the migration and aggregation of active particles. Therefore, strictly controlling the zinc particle size in the zinc anode is crucial for improving the performance stability of aqueous zinc-ion batteries.

[0003] Chinese patent CN118039888A discloses a vertical graphene-modified zinc anode material for zinc-ion batteries. This method involves depositing zinc nanoparticles in porous carbon followed by the growth of vertical graphene, utilizing the vertical structure of graphene to guide zinc deposition. A drawback of this method is that the pre-deposited zinc nanoparticles are prone to migration and aggregation during subsequent graphene growth, leading to increased zinc particle size and decreased uniformity of distribution. Chinese patent CN118039814A discloses a metal-doped zinc anode material for zinc-ion batteries. This method involves depositing zinc nanoparticles and doped metals in a carbon matrix using an arc plasma method, followed by carbon coating. A similar drawback is that zinc deposition and carbon coating are performed in steps, and the deposited zinc nanoparticles lack immediate anchoring during subsequent coating, making them prone to aggregation. Both of these existing technologies employ a "zinc-first, modification-later" preparation process, and the problem of zinc nanoparticle migration and aggregation during subsequent processing remains unresolved.

[0004] In the field of silicon-carbon anode materials, there are reports of technologies for preparing composite materials by alternating deposition of silicon and carbon sources (such as CN116914112A). However, this type of method cannot be directly applied to zinc-carbon composite materials because zinc metal particles and non-metallic silicon particles have different deposition properties. Zinc has a low melting point (approximately 419°C) and high surface diffusion capacity. Without nucleation guidance, it is more prone to particle melting and agglomeration on the carbon matrix during deposition and subsequent processing, and it cannot selectively deposit within the nanopores of carbon.

[0005] Therefore, how to uniformly anchor extremely small zinc particles within the nano or submicron pores of a carbon matrix to obtain a negative electrode material suitable for aqueous zinc-ion batteries remains a technical challenge that urgently needs to be solved. Summary of the Invention

[0006] Due to the aforementioned defects in existing technologies, this invention provides a zinc battery anode material, its preparation method, and a zinc-ion battery. By uniformly anchoring extremely small zinc particles within the nanopores of a carbon matrix, this invention solves the problem that existing zinc battery anode materials are prone to migration and aggregation during electrochemical reactions, leading to increased zinc particle size, decreased distribution uniformity, increased hydrogen evolution side reactions, and affecting zinc utilization and material cycle stability.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a zinc battery anode material, wherein the zinc battery anode material is a composite of a carbon substrate material and zinc nanoparticles; the carbon substrate material is a porous carbon material having through-nano or submicron pores, the zinc nanoparticles are distributed within the pores of the carbon substrate material, the surface of the zinc nanoparticles is wrapped by a carbon network, and the carbon network anchors the zinc nanoparticles within the pores of the carbon substrate material.

[0008] In the above technical solution, the encapsulation effect of the carbon network anchors the zinc nanoparticles inside the nano or submicron pores. This not only controls the size of the zinc particles and improves the utilization rate of zinc during long-term electrochemical cycling, but also reduces the direct contact area between zinc and electrolyte, which helps to suppress side reactions such as hydrogen evolution.

[0009] In some embodiments, the zinc nanoparticles have a particle size of 10 nm to 28 nm, and the zinc content in the zinc battery anode material is 56% to 59% by mass. Thus, the zinc battery anode material not only has good cycle stability but also high volumetric and gravimetric energy density.

[0010] Secondly, the present invention provides a method for preparing a zinc battery anode material, which is used to prepare the zinc battery anode material as described above, comprising the following steps:

[0011] S1, a porous carbon substrate material with through-nano or submicron pores is placed in a reaction chamber, a mixed gas containing active treatment gas and carrier gas is introduced, and a plasma generator is turned on for pretreatment to introduce functional groups on the surface of the carbon substrate material and the inner wall of the pores.

[0012] S2, a mixture of zinc source and carrier gas is introduced into the reaction chamber, and the plasma generator is turned on. Under the action of plasma, the zinc source dissociates into zinc atoms. The zinc atoms preferentially adsorb and nucleate at the functional groups on the inner wall of the pores of the carbon substrate material, and grow into zinc nanoparticles.

[0013] S3, stop the zinc source supply, and introduce carrier gas into the reaction chamber for the first intermittent purging to remove residual zinc source gas;

[0014] S4. A mixture of carbon source and carrier gas is introduced into the reaction chamber, and the plasma generator is turned on. The carbon source dissociates into carbon active fragments under the action of plasma. The carbon active fragments migrate and bond on the surface and in the pores of the carbon substrate material on which zinc nanoparticles are deposited, and grow to form a carbon network. The carbon network encapsulates the zinc nanoparticles and anchors them in the pores of the carbon substrate material.

[0015] S5, stop the carbon source supply, and introduce carrier gas into the reaction chamber for a second interval purging to remove residual carbon source gas;

[0016] S6. Repeat steps S2 to S5 until the preset number of pulse cycles is reached to obtain a composite material of carbon substrate and zinc nanoparticles.

[0017] This preparation method is designed based on the unique physicochemical characteristics of zinc materials:

[0018] First, regarding the pretreatment design for step S1. Zinc ions (Zn 2+ It has a strong coordination ability with nitrogen- and oxygen-containing functional groups. In step S1, such functional groups are introduced into the inner wall of the carbon substrate pores through plasma pretreatment. The purpose of this design is to significantly reduce the nucleation barrier of zinc atoms, guide zinc to preferentially nucleate inside the pores, and avoid disorderly deposition on the outer surface to form dendrites.

[0019] Second, regarding the design of the interval purging steps S3 and S5. The purpose of the interval purging steps is to remove residual zinc or carbon sources in the gas phase, prevent the zinc and carbon sources from mixing and reacting in the gas phase to generate byproducts such as zinc carbide, and ensure the purity of the carbon network and its encapsulation effect on zinc particles.

[0020] Third, regarding the design of the immediate carbon network deposition in step S4. Based on the characteristic of zinc's easy migration and aggregation, step S4 immediately introduces a carbon source after zinc deposition, allowing active carbon fragments to grow and form a carbon network in the area where zinc nanoparticles have just been deposited. The design aims to achieve "deposition as anchoring," so that the newly deposited zinc particles are immediately wrapped by the carbon network, thereby inhibiting particle migration and aggregation in subsequent processing.

[0021] Fourth, regarding the pulse cycle design of step S6. By repeating steps S2 to S5, the layer-by-layer deposition and anchoring of zinc nanoparticles are achieved. Zinc deposition and carbon anchoring are completed sequentially within each pulse cycle, forming a synchronous construction of "deposition-anchoring".

[0022] Based on the above design, the "deposition-anchoring" synchronous construction process of the present invention is adapted to the alternating deposition of zinc and carbon anodes, and utilizes the carbon network to achieve spatial positioning, physical isolation and side reaction suppression of zinc particles during zinc battery cycling.

[0023] In some embodiments, in step S1, the active treatment gas is one or more of ammonia, hydrogen, or water vapor, the volume ratio of the active treatment gas to the carrier gas is 1:9 to 1:2, the pretreatment temperature is 100°C to 250°C, and the pretreatment time is 10 minutes to 40 minutes. The functional groups introduced on the carbon substrate surface through pretreatment serve as preferential nucleation sites for zinc atom deposition, guiding zinc atoms to oriented nucleate on the inner wall of the pores.

[0024] In some embodiments, the carbon substrate material is one or more of the following: porous carbon microspheres, ordered mesoporous carbon (such as CMK-3, CMK-5, etc.), activated carbon (with abundant micropores / mesoporosis), carbon aerogel (with three-dimensional interconnected nanopores), porous carbon prepared by template method (such as zeolite template carbon, silica template carbon, etc.), and biomass-derived porous carbon (such as walnut shell carbon, bamboo charcoal, etc., as long as the pore size is in the nanometer / submicrometer range and is interconnected).

[0025] In some embodiments, in step S2, the zinc source is introduced for 3 to 10 seconds; in step S4, the carbon source is introduced for 5 to 15 seconds; the ratio of zinc source introduction time to carbon source introduction time in each pulse cycle is 1:1 to 1:3; the zinc source is one or more of diethylzinc, dimethylzinc, or zinc acetate vapor, and the volume concentration of the zinc source in the mixed gas is 0.5% to 5%; the carbon source is one or more of methane, acetylene, ethylene, or ethane, and the volume concentration of the carbon source in the mixed gas is 5% to 20%. Because zinc has a low melting point (approximately 419°C) and high surface diffusion capacity, it is prone to particle melting and agglomeration at higher temperatures or during long-term deposition. Therefore, step S2 employs short deposition time (3–10 seconds) to control particle size and avoid particle melting and agglomeration due to long-term deposition or high temperatures. By controlling the introduction time ratio, the matching relationship between the amount of zinc deposited and the amount of carbon network growth in each cycle is adjusted, enabling the carbon network to encapsulate the zinc nanoparticles deposited in that cycle.

[0026] In some embodiments, during the repetition of steps S2 to S5, in one or more pulse cycles after a preset number of pulse cycles, the gas introduced in step S4 is a mixture of a carbon source, a dopant source, and a carrier gas, wherein the volume concentration of the dopant source in the mixture is 0.1% to 1%. By introducing a dopant source to form a dopant element distribution in the carbon network, the chemical affinity between the doped carbon network and zinc ions is enhanced.

[0027] In some embodiments, the dopant source is one or more selected from pyridine, acetonitrile, ammonia, carbon dioxide, carbon monoxide, ethanol vapor, hydrogen sulfide, thiophene, or dimethyl sulfoxide vapor. After the dopant source dissociates under the action of plasma, its dopant element is introduced into the carbon network to form a nitrogen-doped, oxygen-doped, or sulfur-doped carbon network.

[0028] In some implementations, step S6 is followed by an annealing step and a gradient cooling step:

[0029] The zinc and carbon sources are stopped, and annealing gas is introduced into the reaction chamber. The mixture is treated at 200°C to 300°C for 30 to 90 minutes. The annealing gas comprises a carrier gas and an active annealing gas, wherein the active annealing gas is one or more of hydrogen, ammonia, or carbon dioxide, and the volume ratio of the active annealing gas to the carrier gas is 1:9 to 1:2. The temperature is then lowered from the annealing temperature to 150°C to 200°C at a cooling rate of 0.5°C / min to 2°C / min, held at that temperature for 20 to 40 minutes, and then lowered to 60°C to 100°C at a cooling rate of 1°C / min to 3°C / min, and allowed to cool naturally to room temperature. Annealing treatment repairs structural defects in the carbon network, and gradient cooling releases thermal stress caused by the difference in thermal expansion coefficients between the carbon network and zinc nanoparticles.

[0030] Finally, the present invention provides a zinc-ion battery comprising a negative electrode, a separator, a positive electrode, and an aqueous electrolyte, wherein the negative electrode comprises a zinc battery negative electrode material as described above or a zinc battery negative electrode material prepared by the preparation method described in any of the preceding claims.

[0031] The above technical solution is only one feasible technical solution of the present invention. The scope of protection of the present invention is not limited thereto. Those skilled in the art can reasonably adjust the specific design according to actual needs.

[0032] Currently reported carbon materials, such as carbon foam and carbon felt, are mostly macroporous carbon materials, with pore sizes typically greater than 1 micrometer, even reaching hundreds of micrometers. While these macroporous channels can support zinc materials, their pore sizes are much larger than zinc nanoparticles, failing to create an effective spatial confinement for the zinc particles. Consequently, zinc is still prone to migration, aggregation, and hydrogen evolution side reactions during electrochemical cycling. In contrast, the invention described above has the following advantages or beneficial effects:

[0033] (1) The negative electrode material of the present invention utilizes a carbon network to anchor zinc nanoparticles within nano- or submicron pores (pore size ≤ 100 nm), forming a size-matched confined space. This not only controls the size of the zinc particles during long-term electrochemical cycling but also reduces the direct contact area between zinc and the electrolyte, helping to suppress side reactions such as hydrogen evolution and improve zinc utilization. This material can improve the uniformity of zinc deposition and the reversibility of electrode reactions, thereby contributing to improving the energy density of the battery.

[0034] (2) Achieving selective deposition, uniform distribution, and in-situ carbon network encapsulation of zinc nanoparticles within nano- or submicron pores (pore size ≤ 100 nm) faces a series of technical challenges, including limited gas mass transfer, difficulty in precisely controlling nucleation sites, and easy clogging of pore openings by nanoparticles. Conventional impregnation or vapor deposition methods are insufficient for this task. This invention pre-treats the carbon substrate with plasma before zinc deposition, introducing nitrogen-, oxygen-, or hydrogen-containing functional groups onto the carbon substrate surface and the inner walls of the pores using an active treatment gas. The nitrogen and oxygen atoms in these functional groups possess lone pairs of electrons, which can form coordinate bonds with zinc atoms, reducing the nucleation barrier of zinc atoms on the carbon substrate surface. During subsequent deposition, zinc atoms preferentially adsorb and nucleate at these functional groups, guiding zinc to be deposited directionally within the carbon substrate pores and preventing zinc accumulation on the outer surface. A synergistic process of "functional group guidance—pulse deposition—instant anchoring" was designed, employing alternating pulsed introduction of zinc and carbon sources, with intermittent purging after each introduction. This process addresses the unique physicochemical characteristics of zinc, such as its low melting point, high surface diffusion capacity, and susceptibility to hydrogen evolution in aqueous electrolytes. This process achieves alternating deposition of zinc nanoparticles and growth of the carbon network. Simultaneously, the carbon network instantly encapsulates and anchors the newly deposited zinc nanoparticles within the pores during formation, preventing migration and aggregation of zinc particles in subsequent pulse cycles. Through this synchronous "deposition-anchoring" construction method, the zinc nanoparticles remain encapsulated by the carbon network throughout the entire preparation process, effectively suppressing particle growth and uneven distribution, thereby improving the structural stability of the composite material and contributing to improved battery cycle performance.

[0035] (3) The particle size of zinc nanoparticles in the zinc-carbon composite material of the present invention can be controlled to be below 28 nm, and the zinc mass content can reach 59%, which can make the capacity retention rate of the assembled aqueous zinc-ion battery reach 89.5% after 500 cycles, and has high volumetric and mass energy density. Attached Figure Description

[0036] The invention, its features and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0037] Figure 1 This is a schematic diagram of the preparation steps of the zinc battery anode material of the present invention.

[0038] Figure 2 This is a scanning electron microscope schematic diagram of the zinc battery anode material prepared in Example 1 of the present invention.

[0039] Figure 3 The first-cycle constant current charge-discharge curve of the zinc battery anode material prepared in Example 1 of this invention at a current density of 500 mA / g. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0041] The reaction apparatus, monomer compounds, and solvents involved in the following examples and embodiments are all commercially available. Among them:

[0042] The porous carbon microspheres were prepared using the hard template method described in the literature "Preparation, Structure Regulation and Supercapacitor Performance Study of Phenolic Resin-Based Porous Carbon Microspheres" (China Doctoral Dissertation Full-Text Database, 2023).

[0043] Diethylzinc (CAS No.: 557-20-0, purity 99.9999%) is a commercially available high-purity product;

[0044] Zinc sulfate (ZnSO4·7H2O, analytical grade) and manganese sulfate (MnSO4·H2O, analytical grade) were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0045] The detection instruments used in the following effect examples are all commercially available, and the detection methods used are existing technologies that can be found in search results.

[0046] Furthermore, the technologies not detailed in the following effect examples are existing technologies that can be retrieved.

[0047] First, this invention provides a zinc battery anode material, which is a composite of a carbon substrate material and zinc nanoparticles; the carbon substrate material is a porous carbon material with through-hole nano- or submicron pores, and the zinc nanoparticles are distributed within the pores of the carbon substrate material. The surface of the zinc nanoparticles is wrapped by a carbon network, which anchors the zinc nanoparticles within the pores of the carbon substrate material; see also... Figure 1 Its preparation method includes the following steps:

[0048] S1, a porous carbon substrate material with through-nano or submicron pores is placed in a reaction chamber, a mixed gas containing active treatment gas and carrier gas is introduced, and a plasma generator is turned on for pretreatment to introduce functional groups on the surface of the carbon substrate material and the inner wall of the pores.

[0049] S2, a mixture of zinc source and carrier gas is introduced into the reaction chamber, and the plasma generator is turned on. Under the action of plasma, the zinc source dissociates into zinc atoms. The zinc atoms preferentially adsorb and nucleate at the functional groups on the inner wall of the pores of the carbon substrate material, and grow into zinc nanoparticles.

[0050] S3, stop the zinc source supply, and introduce carrier gas into the reaction chamber for the first intermittent purging to remove residual zinc source gas;

[0051] S4. A mixture of carbon source and carrier gas is introduced into the reaction chamber, and the plasma generator is turned on. The carbon source dissociates into carbon active fragments under the action of plasma. The carbon active fragments migrate and bond on the surface and in the pores of the carbon substrate material on which zinc nanoparticles are deposited, and grow to form a carbon network. The carbon network encapsulates the zinc nanoparticles and anchors them in the pores of the carbon substrate material.

[0052] S5, stop the carbon source supply, and introduce carrier gas into the reaction chamber for a second interval purging to remove residual carbon source gas;

[0053] S6. Repeat steps S2 to S5 until the preset number of pulse cycles is reached to obtain a composite material of carbon substrate and zinc nanoparticles.

[0054] In the composite of the carbon substrate material and zinc nanoparticles, the carbon network encapsulates the zinc nanoparticles within nano- or submicron pores. This not only controls the size of the zinc particles and improves zinc utilization during long-term electrochemical cycling, but also reduces the direct contact area between zinc and the electrolyte, helping to suppress side reactions such as hydrogen evolution and effectively improving the energy density and cycle stability of zinc-ion batteries.

[0055] The carbon substrate material can be one or more of the following: porous carbon microspheres, ordered mesoporous carbon (such as CMK-3, CMK-5, etc.), activated carbon (with abundant micropores / mesopores), carbon aerogel (with three-dimensional interconnected nanopores), porous carbon prepared by template method (such as zeolite templated carbon, silica templated carbon, etc.), and biomass-derived porous carbon (such as walnut shell carbon, bamboo charcoal, etc., as long as the pore size is in the nanometer / submicrometer range and is interconnected). Although all of the above materials are suitable as the carbon substrate material of this technical solution, the following points should be noted when using them:

[0056] Pore ​​structure integrity: Plasma treatment is a surface etching process. For micropores with extremely small pore sizes (e.g., <2 nm), excessive or improper treatment can lead to pore structure collapse. Therefore, it is necessary to optimize treatment parameters (such as power, time, and gas type) to find a balance between introducing functional groups and preserving the pore structure.

[0057] Gas-phase mass transfer efficiency: For materials with complex pore networks (such as carbon aerogels), it is necessary to ensure that the active gas can diffuse sufficiently into the pores inside the material to achieve uniform functionalization modification. The design and parameter selection of the plasma processing system are crucial.

[0058] Uniformity of dopant elements: Dopant elements (such as nitrogen) introduced via plasma are mainly concentrated in the near-surface region of the material. For doping within the bulk phase, it may be necessary to combine other methods (such as high-temperature annealing) to promote the diffusion of dopant elements and obtain a more uniform modification effect.

[0059] The active treatment gas can be one or more of ammonia, hydrogen, or water vapor, selected according to the type of functional group to be introduced (e.g., nitrogen-containing, oxygen-containing, or hydrogen-containing functional groups) and the required coordination affinity between zinc atoms and functional groups. During the repetition of steps S2 to S5, in one or more pulse cycles after a preset number of pulse cycles, the gas introduced in step S4 can be a mixture of a carbon source, a dopant source, and a carrier gas, wherein the volume concentration of the dopant source in the mixture is 0.1% to 1%. By introducing the dopant source to form a dopant element distribution in the carbon network, the chemical affinity between the doped carbon network and zinc ions is enhanced. The dopant source can be one or more of pyridine, acetonitrile, ammonia, carbon dioxide, carbon monoxide, ethanol vapor, hydrogen sulfide, thiophene, or dimethyl sulfoxide vapor.

[0060] The step S6 may further include S7, an annealing process, and S8, a gradient cooling process.

[0061] The zinc and carbon sources are stopped, and annealing gas is introduced into the reaction chamber. The mixture is treated at 200°C to 300°C for 30 to 90 minutes. The annealing gas comprises a carrier gas and an active annealing gas, wherein the active annealing gas is one or more of hydrogen, ammonia, or carbon dioxide, and the volume ratio of the active annealing gas to the carrier gas is 1:9 to 1:2. The temperature is then lowered from the annealing temperature to 150°C to 200°C at a cooling rate of 0.5°C / min to 2°C / min, held at that temperature for 20 to 40 minutes, and then lowered to 60°C to 100°C at a cooling rate of 1°C / min to 3°C / min, and allowed to cool naturally to room temperature. Annealing treatment repairs structural defects in the carbon network, and gradient cooling releases thermal stress caused by the difference in thermal expansion coefficients between the carbon network and zinc nanoparticles.

[0062] The technical solution of the present invention will now be described in detail with reference to specific embodiments and comparative examples.

[0063] Example 1

[0064] This embodiment provides a zinc battery anode material and its preparation method, the specific steps of which are as follows:

[0065] S1, porous carbon microspheres (whose pores exhibit a wide distribution, i.e., simultaneously containing a large number of micropores smaller than 10 nm (e.g., 2~5 nm), mesopores around 10 nm, and pores larger than 10 nm (e.g., 15~30 nm), with an average pore size of 10 nm and a specific surface area of ​​1200 m²). 2The carbon microspheres ( / g) were placed in the reaction chamber of a plasma-enhanced chemical vapor deposition (PECVD) apparatus. A mixture of ammonia and argon gas (volume ratio 1:4) was introduced into the reaction chamber. The plasma generator was turned on at 200W, and the microspheres were pretreated at 150°C for 30 minutes to introduce nitrogen-containing functional groups onto the surface and inner walls of the pores. After pretreatment, the plasma generator was turned off, and the system was evacuated until the background pressure was below 5 Pa.

[0066] S2, a mixture of zinc source and argon gas is introduced into the reaction chamber. The zinc source is diethylzinc (liquid zinc source, introduced by bubbling), with a volume concentration of 1%. The plasma generator is turned on at a power of 300W, and the deposition time is 5 seconds. Under the action of plasma, diethylzinc dissociates into zinc atoms. The zinc atoms preferentially adsorb and nucleate at the nitrogen-containing functional groups on the inner wall of the porous carbon microspheres, growing into zinc nanoparticles.

[0067] S3, stop the flow of diethylzinc, and introduce argon gas into the reaction chamber for the first intermittent purging for 2 seconds to remove residual diethylzinc gas.

[0068] S4. A mixture of methane and argon gas is introduced into the reaction chamber, with a methane volume concentration of 10%. The plasma generator is turned on at a power of 400W, and the deposition time is 8 seconds. Under the action of plasma, methane dissociates into carbon active fragments. These carbon active fragments migrate and bond on the surface and within the pores of porous carbon microspheres containing zinc nanoparticles, growing to form a carbon network. This carbon network encapsulates the zinc nanoparticles and anchors them within the pores of the porous carbon microspheres.

[0069] S5, stop the methane supply and introduce argon gas into the reaction chamber for a second intermittent purging for 2 seconds to remove residual methane gas.

[0070] S6. Repeat steps S2 to S5 a total of 200 times to obtain a composite of porous carbon microspheres and zinc nanoparticles. See also Figure 2 The resulting composite contains zinc nanoparticles with a particle size of 10 nm to 25 nm, which are uniformly distributed within the carbon network, and the zinc content is 58% by mass.

[0071] It's important to note the in-situ growth mechanism of zinc nanoparticles: The zinc source (diethylzinc) has a molecular size of approximately 0.6 nm, allowing it to freely diffuse into almost all pores (including those smaller than 10 nm). Under the plasma action of the S2 step, the zinc source decomposes and nucleates at functional group sites on the inner wall of the pores. The initially formed zinc atoms / minimal clusters (<1 nm in size) continue to grow. When they grow to near the pore diameter, the pore walls physically restrict further growth, naturally forming particles with a diameter comparable to the pore size. Therefore, the final particle size of the zinc particles is largely determined by the diameter of the pores they inhabit. The particle size range of 10-25 nm precisely reflects the distribution range of pore sizes in carbon substrates.

[0072] For pores smaller than the zinc particle size (such as 2-5 nm micropores), zinc particles cannot enter, but these micropores mainly serve as gas diffusion channels and anchoring support points. During growth, the carbon network covers these micropore regions, forming stable "anchors" that anchor the larger pores containing zinc particles to the carbon substrate.

[0073] In addition, some zinc may exist in the micropores in the form of extremely small clusters (<2nm), which, although not accounting for the main mass, also contribute to the overall structural stability.

[0074] Example 2

[0075] This embodiment is basically the same as Example 1, except that in step S1, the active treatment gas is hydrogen, the volume ratio of hydrogen to argon is 1:4, the pretreatment temperature is 200℃, and the pretreatment time is 20 minutes. The remaining steps are the same as in Example 1. The zinc nanoparticles in the obtained composite have a particle size of 12nm to 28nm, and the zinc mass content is 56%.

[0076] Example 3

[0077] This embodiment is basically the same as Embodiment 1, except that in the repetition of steps S2 to S5, the parameters of Embodiment 1 are followed for the first 150 cycles, and in the last 50 cycles, the gas introduced in step S4 is a mixture of methane, pyridine, and argon, with a pyridine volume concentration of 0.5%. The remaining steps are the same as in Embodiment 1. The zinc nanoparticles in the obtained composite have a particle size of 10 nm to 25 nm, a zinc mass content of 59%, and an outer carbon network that is a nitrogen-doped carbon network.

[0078] Example 4

[0079] This embodiment is basically the same as Embodiment 1, except that after step S6, it includes an annealing step and a gradient cooling step: the introduction of diethylzinc and methane is stopped, and a mixture of hydrogen and argon gas is introduced into the reaction chamber at a volume ratio of 1:4. Annealing is performed at 250°C for 60 minutes. After annealing, the temperature is lowered to 180°C at a rate of 1°C / min, held for 30 minutes, and then lowered to 80°C at a rate of 2°C / min, allowing it to cool naturally to room temperature. The remaining steps are the same as in Embodiment 1. The resulting composite contains zinc nanoparticles with a particle size of 10 nm to 25 nm and a zinc mass content of 58%. Annealing and gradient cooling do not significantly reduce the particle size of zinc nanoparticles, but rather: repair structural defects in the carbon network (improving the graphitization degree and chemical stability of the carbon network); and release thermal stress caused by the difference in thermal expansion coefficients between the carbon network and zinc nanoparticles (avoiding interfacial delamination and ensuring long-term stability of the anchoring structure).

[0080] Comparative Example 1

[0081] This comparative example uses pure zinc sheet as the negative electrode material. The zinc sheet is 0.1 mm thick and has a purity of 99.9%. Before use, the zinc sheet is immersed in acetone and ethanol in sequence, ultrasonically cleaned for 30 minutes, and then air-dried.

[0082] Comparative Example 2

[0083] This comparative example is basically the same as Example 1, except that the pretreatment in step S1 is omitted, and the porous carbon microspheres are directly placed in the reaction chamber for deposition in steps S2 to S6. The remaining steps are the same as in Example 1. The zinc nanoparticles in the obtained composite have a particle size of 30 nm to 80 nm, are unevenly distributed, and some particles aggregate on the outer surface of the carbon microspheres.

[0084] Comparative Example 3

[0085] This comparative example is basically the same as Example 1, except that in the repeated steps S2 to S5, a mixed gas of diethylzinc and methane is simultaneously introduced for deposition, instead of pulsed alternating introduction. The total deposition time is (5s + 8s) × 200 = 2600 seconds, and other parameters are the same as in Example 1. The zinc nanoparticles in the obtained composite have a particle size of 40nm to 100nm, with a large number of particles agglomerated on the outer surface of the carbon microspheres and a relatively small amount deposited in the pores.

[0086] The specific battery assembly and testing methods are as follows:

[0087] Negative electrode preparation: The negative electrode materials prepared in Examples 1-4 and Comparative Examples 2-3, the conductive agent acetylene black, and the binder polyvinylidene fluoride were mixed at a mass ratio of 8:1:1. N-methylpyrrolidone was added and ground evenly. The mixture was then coated onto a copper foil current collector and dried in a vacuum drying oven at 60°C for 12 hours. The resulting material was then cut into circular electrode sheets with a diameter of 12 mm using a die-cutting machine. For the pure zinc sheet in Comparative Example 1, it was directly cut into circular electrode sheets with a diameter of 12 mm.

[0088] Preparation of positive electrode sheet: Manganese dioxide (electrolytic manganese dioxide, battery grade), acetylene black and polyvinylidene fluoride are mixed in a mass ratio of 7:2:1, N-methylpyrrolidone is added and ground evenly, coated on stainless steel foil current collector, dried in a vacuum drying oven at 60℃ for 12 hours, and cut into circular electrode sheets with a diameter of 12mm using a punching machine.

[0089] Electrolyte preparation: Weigh zinc sulfate (ZnSO4·7H2O, analytical grade) and manganese sulfate (MnSO4·H2O, analytical grade), dissolve them in deionized water, and prepare an aqueous solution of 2.0 mol / L zinc sulfate and 0.1 mol / L manganese sulfate.

[0090] Battery Assembly: In an air environment, assemble the CR2032 coin cell in the following order: positive electrode shell, positive electrode plate, separator (glass fiber filter paper, 16mm in diameter), negative electrode plate, gasket, spring contact, and negative electrode cap. Inject 100μL of pre-prepared electrolyte (2.0 mol / L ZnSO4 + 0.1 mol / L MnSO4 aqueous solution) into each cell, seal with a sealing machine, and let stand for 4 hours.

[0091] Charge / discharge test: Constant current charge / discharge test was conducted at room temperature using a battery testing system (Wuhan Landian CT2001A). Test parameters were: voltage range 0.02V to 3V, current density 500mA / g (calculated based on the mass of active material in the negative electrode material), with discharge followed by charging.

[0092] Cyclic performance test: Record the initial discharge specific capacity and the discharge specific capacity after 500 cycles, and calculate the capacity retention rate.

[0093] The test results are as follows:

[0094] The electrochemical performance of the negative electrode materials prepared in Examples 1-4 and Comparative Examples 1-3 was tested according to the above test method, and the results are as follows: Figure 3 As shown in Table 1. Combined with... Figure 3 The charge-discharge curves of Example 1 show a typical charge-discharge plateau, with an initial discharge specific capacity of 550 mAh / g, while the pure zinc sheet in Comparative Example 1 only has 183 mAh / g. This indicates that the composite anode material prepared by the method of the present invention significantly improves the utilization rate of zinc, thereby increasing the energy density.

[0095] Table 1. Battery performance test results of the examples and comparative examples.

[0096]

[0097] As can be seen from the test results in Table 1, the initial discharge specific capacity of Examples 1 to 4 all reached over 370 mAh / g, and the capacity retention rate after 500 cycles all reached over 83%, which is significantly better than that of Comparative Examples 1 to 3.

[0098] In summary, the zinc battery anode material, its preparation method, and the zinc-ion battery provided by this invention solve the problem that existing zinc battery anode materials are prone to migration and aggregation during electrochemical reactions, leading to increased zinc particle size, decreased distribution uniformity, increased hydrogen evolution side reactions, and affecting the cycle stability of the material by uniformly anchoring extremely small zinc particles within the nanopores of a carbon matrix.

[0099] Those skilled in the art should understand that variations can be implemented by combining existing technology with the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention, and will not be elaborated here either.

[0100] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A zinc battery anode material, characterized in that: The zinc battery anode material is a composite of a carbon substrate material and zinc nanoparticles; the carbon substrate material is a porous carbon material with through-nano or submicron pores, the zinc nanoparticles are distributed in the pores of the carbon substrate material, the surface of the zinc nanoparticles is wrapped by a carbon network, and the carbon network anchors the zinc nanoparticles in the pores of the carbon substrate material.

2. The zinc battery negative electrode material according to claim 1, characterized in that, The zinc nanoparticles have a particle size of 10 nm to 28 nm, and the zinc content in the zinc battery anode material is 56% to 59% by mass.

3. A method for preparing a zinc battery negative electrode material, characterized in that, The preparation of the zinc battery anode material as described in claim 1 or 2 includes the following steps: S1, a porous carbon substrate material with through-nano or submicron pores is placed in a reaction chamber, a mixed gas containing active treatment gas and carrier gas is introduced, and a plasma generator is turned on for pretreatment to introduce functional groups on the surface of the carbon substrate material and the inner wall of the pores. S2, a mixture of zinc source and carrier gas is introduced into the reaction chamber, and the plasma generator is turned on. Under the action of plasma, the zinc source dissociates into zinc atoms. The zinc atoms preferentially adsorb and nucleate at the functional groups on the inner wall of the pores of the carbon substrate material, and grow into zinc nanoparticles. S3, stop the zinc source supply, and introduce carrier gas into the reaction chamber for the first intermittent purging to remove residual zinc source gas; S4. A mixture of carbon source and carrier gas is introduced into the reaction chamber, and the plasma generator is turned on. The carbon source dissociates into carbon active fragments under the action of plasma. The carbon active fragments migrate and bond on the surface and in the pores of the carbon substrate material on which zinc nanoparticles are deposited, and grow to form a carbon network. The carbon network encapsulates the zinc nanoparticles and anchors them in the pores of the carbon substrate material. S5, stop the carbon source supply, and introduce carrier gas into the reaction chamber for a second interval purging to remove residual carbon source gas; S6. Repeat steps S2 to S5 until the preset number of pulse cycles is reached to obtain a composite material of carbon substrate and zinc nanoparticles.

4. The method for preparing a zinc battery negative electrode material according to claim 3, characterized in that, In step S1, the active treatment gas is one or more of ammonia, hydrogen, or water vapor, the volume ratio of the active treatment gas to the carrier gas is 1:9 to 1:2, the pretreatment temperature is 100℃ to 250℃, and the pretreatment time is 10 minutes to 40 minutes.

5. The method for preparing a zinc battery negative electrode material according to claim 3, characterized in that, The porous carbon substrate material is one or more of the following: porous carbon microspheres, ordered mesoporous carbon, activated carbon, carbon aerogel, porous carbon prepared by template method, and biomass-derived porous carbon.

6. The method for preparing a zinc battery negative electrode material according to claim 3, characterized in that, In step S2, the zinc source is introduced for 3 to 10 seconds; in step S4, the carbon source is introduced for 5 to 15 seconds; the ratio of the zinc source introduction time to the carbon source introduction time in each pulse cycle is 1:1 to 1:3; the zinc source is one or more of diethylzinc, dimethylzinc, or zinc acetate vapor, and the volume concentration of the zinc source in the mixed gas is 0.5% to 5%; the carbon source is one or more of methane, acetylene, ethylene, or ethane, and the volume concentration of the carbon source in the mixed gas is 5% to 20%.

7. The method for preparing a zinc battery negative electrode material according to claim 3, characterized in that, During the repetition of steps S2 to S5, in one or more pulse cycles after a preset number of pulse cycles, the gas introduced in step S4 is a mixture of carbon source, dopant source and carrier gas, and the volume concentration of the dopant source in the mixture is 0.1% to 1%.

8. The method for preparing a zinc battery negative electrode material according to claim 7, characterized in that, The doping source is one or more of pyridine, acetonitrile, ammonia, carbon dioxide, carbon monoxide, ethanol vapor, hydrogen sulfide, thiophene, or dimethyl sulfoxide vapor.

9. The method for preparing a zinc battery negative electrode material according to claim 3, characterized in that, Step S6 is followed by an annealing step and a gradient cooling step: Stop the flow of zinc and carbon sources, introduce annealing gas into the reaction chamber, and treat at 200°C to 300°C for 30 to 90 minutes; the annealing gas includes a carrier gas and an active annealing gas, wherein the active annealing gas is one or more of hydrogen, ammonia, or carbon dioxide, and the volume ratio of the active annealing gas to the carrier gas is 1:9 to 1:2; then cool from the annealing temperature to 150°C to 200°C at a cooling rate of 0.5°C / min to 2°C / min, hold at that temperature for 20 to 40 minutes, and then cool to 60°C to 100°C at a cooling rate of 1°C / min to 3°C / min, and allow to cool naturally to room temperature.

10. A zinc-ion battery, comprising a negative electrode, a separator, a positive electrode, and an aqueous electrolyte, characterized in that, The negative electrode includes the zinc battery negative electrode material as described in claim 1 or 2, or the zinc battery negative electrode material prepared by the preparation method as described in any one of claims 3 to 9.

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