A composite zinc negative electrode constructed by self-assembly and in-situ polymerization and a preparation method and application thereof

Abstract

This invention provides a composite zinc anode constructed through self-assembly and in-situ polymerization, its preparation method, and its applications. It consists of a bottom zinc metal layer and a top fullerene-based modification layer. The modification layer forms a robust cross-linked network film through the polymerization of fullerene molecules and their chemical bonding with the zinc metal surface. This invention not only improves the ion desolvation efficiency and homogenizes the electric field distribution on the zinc anode surface, but also, relying on the stable interface formed by polymerization and bonding, allows the modification layer to adhere tightly to the zinc metal surface, effectively adapting to the volume changes of the zinc anode during cycling, avoiding coating peeling or uniformity degradation, thereby significantly extending the battery's cycle life. The preparation method involves coating a fullerene-based molecular solution onto the zinc metal surface, followed by polymerization and bonding treatment to form the composite zinc anode structure. This invention features a simple process, and the resulting composite zinc anode has outstanding practicality and promotional value in aqueous zinc metal batteries.

Description

Technical Field

[0001] This invention relates to the field of aqueous zinc metal batteries, and in particular to a composite zinc anode constructed by self-assembly and in-situ polymerization, its preparation method, and its application. Background Technology

[0002] With the increasing demand for electrochemical energy storage systems, the development of battery systems that combine high safety, low cost, and environmental friendliness has become a research focus. Aqueous zinc metal batteries, which use an aqueous electrolyte to replace traditional organic electrolytes, fundamentally eliminate the risks of combustion and explosion, and have outstanding advantages such as high intrinsic safety, low raw material cost, and environmental friendliness, making them an important development direction for next-generation large-scale energy storage technology. However, problems such as uncontrolled dendrite growth, hydrogen evolution corrosion, and surface passivation in zinc metal anodes during cycling severely restrict their cycle life and commercialization. Therefore, constructing a functional modification layer on the surface of the zinc anode has become a key strategy to improve its interfacial stability, but existing technologies still have significant shortcomings in terms of interfacial bonding strength, component uniformity, and overall conductivity.

[0003] To clearly illustrate the limitations of existing technologies, typical solutions and their main drawbacks are described below:

[0004] (1) Porous coating strategy: Taking Chinese patent application CN108520985A as an example, this scheme aims to physically control the zinc ion flow distribution by coating the zinc anode surface with a porous coating formed by nanomaterials and polymer binders (such as polyvinylidene fluoride). However, this strategy has significant drawbacks: the binder matrix with low zinc affinity significantly increases the interfacial impedance, hindering ion / electron transport; at the same time, the simple physical coating process means that the coating and the zinc substrate are only bound by weak physical adsorption, which makes it easy to fall off under the volume change during the zinc deposition / stripping process, and it is difficult to ensure the uniformity of component distribution.

[0005] (2) Organic molecule modification layer strategy: As shown in Chinese patent application CN119208610A, this technology utilizes synthetic molecules (LXB) containing heteroatoms such as S, O, and N to coordinate with zinc ions, thereby guiding the uniform deposition of zinc ions. However, its regulatory effect is limited by the low proportion of effective active sites in the molecular structure, resulting in limited effectiveness. More importantly, this strategy still relies on binders such as polyvinylidene fluoride to fix the active molecules, which not only reduces the uniformity of zinc affinity at the interface but also poses a risk of coating peeling due to the lack of strong chemical bonding with the zinc substrate.

[0006] (3) Fullerene / polymer composite layer strategy: Relevant literature studies (such as Chem. Eng. J. 2023, 466, 143054) adopt the strategy of using fullerene (C 60The process involves mechanically mixing fullerenes with binders such as carboxymethyl cellulose (CMC) followed by coating. Although fullerenes themselves possess excellent electric field homogenization and zinc affinity, the introduction of polymer binders with low zinc affinity sacrifices the overall zinc affinity and energy density of the system. More importantly, the mechanical mixing and physical coating process easily leads to uneven dispersion of functional materials, and the lack of strong interaction between the modified layer and the zinc substrate results in delamination due to interfacial stress during long-term cycling, making it difficult to maintain long-term protective functions.

[0007] In summary, existing technologies generally face the following common bottlenecks: First, the relationship between the modification layer and the zinc metal substrate mainly relies on physical adhesion or van der Waals forces, lacking strong and stable chemical bonding, resulting in poor interfacial mechanical stability; second, functional materials are usually encapsulated in a polymer binder matrix, which not only limits the uniformity of interfacial reaction kinetics but also leads to uneven dispersion of functional components, affecting the reliability of protection; third, the proportion of functional components in the composite anode is relatively low, making it difficult to exert sufficient functional effects.

[0008] To address the aforementioned fundamental shortcomings, this invention innovatively proposes a strategy of constructing a stable functional modification layer through integrated intermolecular polymerization and interfacial chemical bonding. Its core advancements lie in: utilizing direct chemical bonding between fullerene molecules and the zinc substrate to achieve robust anchoring of the modification layer, effectively resisting volumetric stress during cycling; simultaneously, forming a three-dimensional cross-linked network through intermolecular polymerization, constructing a continuous film with a uniform structure, rich in delocalized electrons, and possessing both high zinc ion conductivity and abundant active sites without introducing any insulating binder. This structural design fundamentally solves the problems of weak interfacial bonding and poor conductivity, synergistically promoting ion desolvation, homogenizing the surface electric field, and suppressing side reactions, thus providing a more effective solution for high-performance and long-life operation of aqueous zinc metal batteries. Summary of the Invention

[0009] To address the above problems, the present invention aims to provide a composite zinc anode constructed through self-assembly and in-situ polymerization, its preparation method, and its application. The technical solution adopted by the present invention is as follows:

[0010] A composite zinc anode constructed by self-assembly and in-situ polymerization consists of a bottom zinc metal layer and a top modification layer arranged sequentially from bottom to top; the bottom zinc metal layer is a zinc metal thin film; the top modification layer is a fullerene-based polymer thin film, and the two are connected by chemical bonding.

[0011] Furthermore, the fullerene-based polymer film refers to a cross-linked network film obtained by intermolecular polymerization between fullerene molecules or by chemical bonding with a zinc substrate.

[0012] Furthermore, the polymerization is achieved through at least one of annealing and radiation treatment.

[0013] Furthermore, the fullerene-based molecule is composed of a fullerene carbon cage portion, a bridging portion, and a terminal group portion, and its general structural formula is:

[0014]

[0015] The fullerene carbon cage portion is C 60 C 70 C 76 C 78 C 80 C 84 One of the following: the bridging part is at least one of chain-like and cyclic structures; the terminal part is at least one of disulfide bond, phosphate monoester group, and phosphonic acid diester group that can undergo cross-linking polymerization; n1 is any integer between 1 and 3; n2 is any integer between 1 and 30.

[0016] A method for preparing a composite zinc anode constructed by self-assembly and in-situ polymerization includes the following steps:

[0017] Step 1: Dissolve the fullerene molecules in a selected solvent to obtain a fullerene molecule solution;

[0018] Step 2: Cut the purchased zinc sheet into pieces. After ultrasonic cleaning in acetone, place the cut zinc sheet in isopropanol for later use.

[0019] Step 3: The fullerene-based molecular solution is coated onto the surface of the bottom zinc metal layer using a liquid-phase film formation method;

[0020] Step 4: Perform polymerization treatment on the coated bottom zinc metal layer to promote intermolecular polymerization of the fullerene molecular end groups or chemical bonding with the zinc substrate to form a top fullerene polymer modification layer, and obtain a composite zinc anode.

[0021] Furthermore, the selected solvent in step one is at least one of aromatic solvents such as benzene, anisole, chlorobenzene, o-dichlorobenzene, and toluene.

[0022] Furthermore, the concentration of the fullerene-based molecular solution in step one is 0.1~100 mg / mL.

[0023] Furthermore, the liquid phase film formation method in step three includes at least one of dip coating, screen printing, roll coating, slot coating, spray coating, spin coating, or inkjet printing.

[0024] Furthermore, the polymerization treatment in step four is either annealing or radiation treatment.

[0025] Furthermore, the annealing temperature is 60~200℃, and the annealing time is 5~180 min.

[0026] Furthermore, the wavelength of the radiation treatment is 170~950 nm, and the power of the radiation treatment is 5~500 mW / cm². 2 The radiation treatment time is 1~180 min.

[0027] Furthermore, the thickness of the top fullerene-based polymer modification layer formed in step four is 10~1000 nm.

[0028] Application of a composite zinc anode constructed through self-assembly and in-situ polymerization in an aqueous zinc metal battery.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) By constructing a stable integrated modification layer through intermolecular polymerization and interfacial chemical bonding, the common problems of weak interfacial bonding and poor zinc ion conductivity in existing technologies are fundamentally solved. Fullerene molecules polymerize to form a three-dimensional cross-linked network, giving the modification layer good structural integrity and mechanical toughness. At the same time, this network is firmly anchored to the bottom zinc metal substrate through chemical bonding, which significantly improves the interfacial bonding strength. It can effectively adapt to the volume changes of the zinc anode during cycling, effectively prevent the modification layer from failing and falling off, and ensure the reliability of long-term protection. In addition, this integrated structure forms a modification layer with a single component, uniform distribution and high zinc ion conductivity without introducing any non-conductive binder, effectively reducing interfacial impedance.

[0031] (2) The fullerene-based polymer modification layer relies on the efficient electron acceptor characteristics of the fullerene carbon cage to promote the uniform delocalization of electrons in the modification layer during the charging and discharging process of the battery, thereby effectively homogenizing the electric field distribution on the zinc negative electrode surface and fundamentally inhibiting the formation and growth of zinc dendrites.

[0032] (3) The high-density delocalized electron system composed of a large number of fullerene units in the modified layer can effectively attract hydrated zinc ions in the electrolyte through Coulomb interaction, significantly accelerating their desolvation process, thereby improving the reversibility and kinetics of zinc ion deposition / stripping and enhancing the cycle stability of the battery.

[0033] (4) The inherent hydrophobic properties of the fullerene carbon cage enable the modified layer to effectively block the direct contact between water molecules in the electrolyte and the surface of the zinc metal anode, thereby significantly inhibiting the hydrogen evolution side reaction, reducing the corrosion and surface passivation of the zinc anode, and helping to maintain the high coulombic efficiency of the battery.

[0034] (5) The modified layer adopts a process combining liquid phase film formation and in-situ polymerization anchoring, which realizes the uniform spreading, synchronous cross-linking and firm bonding of fullerene molecules on the zinc metal surface, forming a modified layer with consistent structure and controllable thickness. By adjusting the liquid phase film formation process, the thickness of the modified layer can be precisely controlled in the range of 10~1000nm.

[0035] In summary, the composite zinc anode provided by this invention, constructed through self-assembly and in-situ polymerization, successfully integrates multiple functions such as strong interfacial bonding, uniform structure, high ionic conductivity, electric field homogenization, promotion of desolvation, and hydrophobic protection through a unique polymerization-bonding composite mechanism. While ensuring the long-term stable adhesion of the modified layer, it significantly optimizes the interfacial ion and charge transport behavior, thereby effectively suppressing dendrite growth and side reactions, and greatly improving the cycle life and overall stability of aqueous zinc metal batteries. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope of protection. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the molecular structure of the fullerene-based molecule S1.

[0038] Figure 2 This is a schematic diagram of the structure of the composite zinc anode PS1 / Zn.

[0039] Figure 3 The images show the surface morphology of the bare zinc anode (Zn) and the composite zinc anode (PS1 / Zn).

[0040] Figure 4 The figure shows the cycle stability test results of aqueous zinc-iodine batteries based on bare zinc anode (Zn) and composite zinc anode (PS1 / Zn).

[0041] Figure 5 This is a schematic diagram of the molecular structure of the fullerene-based molecule S2.

[0042] Figure 6 The surface potential distribution of bare zinc (Zn) and fullerene-based polymer modified layer PS2 is shown.

[0043] Figure 7 The figure shows the cycle stability test results of aqueous zinc-iodine batteries based on bare zinc anode (Zn) and composite zinc anode (PS2 / Zn).

[0044] Figure 8The contact angle test results are shown for a 2 M zinc sulfate aqueous solution on the surface of bare zinc Zn and fullerene-based polymer modified layer PS1.

[0045] Figure 9 The figure shows the cycle stability test results of aqueous zinc-iodine batteries based on bare zinc anode (Zn) and composite zinc anode (PS1 / Zn, thick coating). Detailed Implementation

[0046] The technical solution of the present invention will be further described clearly and completely below with reference to the embodiments and accompanying drawings.

[0047] Example 1

[0048] This embodiment provides a composite zinc anode (named PS1 / Zn), consisting of a bottom zinc metal layer and a top fullerene-based polymer modification layer arranged sequentially from bottom to top. The bottom zinc metal layer is made of commercially available zinc sheet. The top fullerene-based polymer modification layer (named PS1) is made of... Figure 1 The fullerene-based molecule shown is (N-phenyl-2-(4-thiocyloxyphenyl)C 70 Fullerene pyrrolidine (named S1) was obtained through polymerization and bonding. The synthesis of the fullerene-based molecule S1 was commissioned to Fujian Fuerjin Biotechnology Co., Ltd.

[0049] In this embodiment, the preparation process of the composite zinc anode is as follows:

[0050] (1) Zinc sheet treatment: Commercially available zinc sheets with a thickness of 200 μm are cut into round zinc sheets with a diameter of 12 mm. The cut round zinc sheets are placed in 200 mL of acetone solution for ultrasonic cleaning for 30 min. The ultrasonically cleaned round zinc sheets are placed in isopropanol solution for later use.

[0051] (2) Solution preparation: Dissolve 5 mg of fullerene molecules S1 in 1 mL of anisole solvent and sonicate for 30 min to obtain an anisole solution with a concentration of 5 mg / mL of fullerene molecules S1.

[0052] (3) Spin coating: Take out the zinc disc from step (1) and dry it with a nitrogen gun. Place it in a spin coater and add 0.1 mL of the anisole solution of fullerene molecule S1 from step (2) to the center of the zinc disc at a speed of 2000 rpm. After adding the solution, keep the spin coater rotating at 2000 rpm for 30 s.

[0053] (4) Polymerization and bonding treatment: The round zinc sheets from step (3) are placed on a 150°C flat plate heater and annealed for 1 h to obtain a composite zinc anode.

[0054] (5) Drying and storage: The composite zinc anode from step (4) is treated in a vacuum oven at 110°C for 12 h and then vacuum stored for later use.

[0055] In this embodiment, the preparation process of the zinc metal battery is as follows:

[0056] (1) The zinc-iodine cathode is prepared into a self-supporting thin film by roll forming process. The composite cathode is composed of zinc iodide, activated carbon, and polytetrafluoroethylene in a mass ratio of 50:40:10, wherein the areal loading of zinc iodide is 10~15 mg / cm³. 2 .

[0057] (2) The battery is assembled using a CR2032 button cell casing, a 304 stainless steel outer shell, gaskets, spring contacts, an electrolyte-wetted separator, and electrodes. Unless otherwise specified, a glass fiber membrane (thickness: 675 μm) is used as the separator, and a 2 M zinc sulfate aqueous solution is used as the electrolyte.

[0058] (3) In the full cell, bare zinc negative electrode Zn and composite zinc negative electrode PF1 / Zn were paired with zinc iodide-based positive electrode to construct control sample and target sample, respectively.

[0059] like Figure 1 As shown, the fullerene carbon cage portion, bridging portion, and terminal group portion of the fullerene-based molecule S1 are composed of fullerene C1, C2, C3, C4, C5, C6, C7, C8, C9 ... 70 Structure, benzoic acid-like benzoyl ester structure, disulfide bond structure.

[0060] like Figure 2 As shown, the disulfide bond structure undergoes cross-linking polymerization and chemical bonding under annealing treatment, polymerizing and bonding the fullerene-based molecule S1 into a fullerene-based polymer modification layer PS1, which is then anchored on the bottom zinc sheet to form a composite zinc anode PS1 / Zn.

[0061] according to Figure 3 Characterization results using scanning electron microscopy (SEM, scale bar: 400 nm) clearly show that the surface of the bare zinc anode (Zn) is rough and uneven. This morphology easily leads to uneven surface potential distribution, further causing local concentration of the interfacial electric field and zinc ion concentration field, thus inducing the growth of zinc dendrites during charge and discharge. In contrast, the composite zinc anode PS1 / Zn exhibits a uniform and dense morphology, which helps to improve the uniformity of the electric field and ion concentration distribution at the electrode-electrolyte interface, thereby enhancing the cycle stability of aqueous zinc metal batteries.

[0062] Figure 4 The results showed that, based on the mass of the zinc iodide positive electrode active material, at 200 mA g... -1The charge-discharge test results at the specified current density showed discharge and charge cutoff voltages of 0.6 V and 1.6 V, respectively, after 1000 cycles. In the aqueous zinc-iodine battery system, the initial discharge specific capacity of the battery using a bare zinc negative electrode was 137.73 mAh g⁻¹. -1 After 553 cycles, it decreased to 99.92 mAh g. -1 The capacity retention rate was only 72%, approaching the failure threshold of conventional batteries. This degradation was mainly due to side reactions such as dendrite growth, hydrogen evolution, and surface passivation of the zinc anode. In contrast, the battery using the composite zinc anode PS1 / Zn had an initial discharge specific capacity of 142.69 mAh g⁻¹. -1 It remained at 135.59 mAh g after 1000 cycles. -1 The capacity decay rate is only 7.11 μAh g per cycle. -1 The overall capacity retention rate reached 95%, and the coulomb efficiency remained at a level close to 100% throughout the entire cycle.

[0063] The above results indicate that the composite zinc anode with fullerene-based polymer-modified PS1 can effectively suppress interfacial side reactions of the zinc anode, significantly improve the uniformity and reversibility of zinc deposition / stripping, and thus greatly improve the long-cycle stability of aqueous zinc-iodine batteries.

[0064] Example 2

[0065] This embodiment provides a composite zinc anode (named PS2 / Zn), consisting of a bottom zinc metal layer and a top fullerene-based polymer modification layer arranged sequentially from bottom to top. The bottom zinc metal layer is made of commercially available zinc sheet. The top fullerene-based polymer modification layer (named PS2) is made of... Figure 5 The fullerene-based molecule shown is (1-[4-(phosphomonoesteryl)butyl]-1-phenyl-[6,6]C 61 The fullerene-based molecule S2 was obtained through polymerization and bonding. The synthesis of S2 was commissioned to Fujian Fuerjin Biotechnology Co., Ltd.

[0066] In this embodiment, the preparation process of the composite zinc anode is as follows:

[0067] (1) Zinc sheet treatment: A commercially available zinc sheet (100 mm * 100 mm) with a thickness of 200 μm was placed in 500 mL of acetone solution for ultrasonic cleaning for 30 min. The ultrasonically cleaned zinc sheet was then placed in isopropanol solution for later use.

[0068] (2) Solution preparation: Dissolve 50 mg of fullerene molecules S2 in 10 mL of anisole solvent and sonicate for 30 min to obtain an anisole solution with a concentration of 5 mg / mL of fullerene molecules S2.

[0069] (3) Slit coating: Take out the zinc sheet from step (1) and dry it with a nitrogen gun. Place it on the slit coating table and add 0.5 mL of the anisole solution of fullerene molecule S2 from step (2) to the side of the zinc sheet near the scraper. Coat the zinc sheet to form a film under the condition that the slit width is 5 μm.

[0070] (4) Polymerization and bonding treatment: The zinc sheet from step (3) is placed on a flat plate heater at 150°C and annealed for 1 h. It is then further cut into round zinc sheets with a diameter of 12 mm to obtain a composite zinc anode.

[0071] (5) Drying and storage: The composite zinc anode from step (4) is treated in a vacuum oven at 110°C for 12 h and then vacuum stored for later use.

[0072] In this embodiment, the preparation process of the zinc metal battery is as follows:

[0073] (1) The zinc-iodine cathode is prepared into a self-supporting thin film by roll forming process. The composite cathode is composed of zinc iodide, activated carbon, and polytetrafluoroethylene in a mass ratio of 50:40:10, wherein the areal loading of zinc iodide is 10~15 mg / cm³. 2 .

[0074] (2) The battery is assembled using a CR2032 button cell casing, a 304 stainless steel outer shell, gaskets, spring contacts, an electrolyte-wetted separator, and electrodes. Unless otherwise specified, a glass fiber membrane (thickness: 675 μm) is used as the separator, and a 2 M zinc sulfate aqueous solution is used as the electrolyte.

[0075] (3) In the full cell, bare zinc negative electrode and composite zinc negative electrode were paired with zinc iodide-based positive electrode to construct control sample and target sample, respectively.

[0076] like Figure 5 As shown, the fullerene carbon cage portion, bridging portion, and terminal group portion of the fullerene-based molecule S2 are composed of fullerene C164, C164, C2 ... 60 The structure includes butyl-like structure and phosphate monoester-based structure. Among them, the phosphate monoester-based structure undergoes cross-linking polymerization and chemical bonding under thermal annealing, polymerizing and bonding the fullerene-based molecule S2 into a fullerene-based polymer modification layer PS2, which is then anchored on the bottom zinc sheet to form a composite zinc anode PS2 / Zn.

[0077] according to Figure 6Characterization results using medium Kelvin probe force microscopy (KPFM) in a 10 μm × 10 μm region revealed that the bare zinc anode (Zn) exhibited a morphology with varying color intensities, indicating significant non-uniformity in its surface potential distribution. This non-uniformity easily leads to localized concentration of the interfacial electric field, thereby inducing the growth of zinc dendrites during cycling. In contrast, the composite zinc anode PS2 / Zn exhibited a uniform surface potential distribution, demonstrating its ability to effectively improve the uniformity of the interfacial electric field of the zinc anode, thus contributing to enhanced cycle stability of aqueous zinc metal batteries.

[0078] Figure 7 This demonstrates the effect of zinc iodide as the active material in the positive electrode at 200 mAg. -1 The charge-discharge test results at the specified current density showed discharge and charge cutoff voltages of 0.6 V and 1.6 V, respectively, after 1000 cycles. The initial discharge specific capacity of the zinc-iodine battery using a bare zinc negative electrode was 139.49 mAhg. -1 After 642 cycles, it decreased to 105.64 mAhg. -1 The capacity retention rate was 75%, approaching the failure standard of conventional batteries. This degradation was mainly due to side reactions such as dendrite growth, hydrogen evolution, and surface passivation of the zinc anode. In contrast, the battery using the composite zinc anode PS2 / Zn had an initial discharge specific capacity of 145 mAhg. -1 It remained at 135.01 mAhg after 1000 cycles. -1 The capacity retention rate reached 93%, and the average capacity decay per cycle was only 9.9 μAhg. -1 Furthermore, the coulomb efficiency remained close to 100% throughout the entire test.

[0079] The above results further demonstrate that the composite zinc anode PS2 / Zn with a fullerene-based polymer-modified layer PS2 can significantly improve the interfacial electric field distribution, suppress dendrite growth and side reactions during zinc deposition, thereby effectively improving the long-cycle stability and capacity retention of aqueous zinc-iodine batteries.

[0080] Example 3

[0081] The fullerene molecule used in this embodiment is the same as the fullerene molecule S1 in Example 1.

[0082] In this embodiment, the preparation process of the composite zinc anode is as follows:

[0083] (1) Zinc sheet treatment: Commercially available zinc sheets with a thickness of about 200 μm are cut into round zinc sheets with a diameter of 12 mm. The cut round zinc sheets are placed in 200 mL of acetone solution for ultrasonic cleaning for 30 min. The ultrasonically cleaned round zinc sheets are placed in isopropanol solution for later use.

[0084] (2) Solution preparation: Dissolve 5 mg of fullerene molecules S1 in 1 mL of anisole solvent and sonicate for 30 min to obtain an anisole solution with a concentration of 5 mg / mL of fullerene molecules S1.

[0085] (3) Spin coating: Take out the zinc disc from step (1) and dry it with a nitrogen gun. Place it in a spin coater and add 0.1 mL of the anisole solution of fullerene molecule S1 from step (2) to the center of the zinc disc at a speed of 2000 rpm. After adding the solution, keep the spin coater rotating at 2000 rpm for 30 s.

[0086] (4) Polymerization and bonding treatment: The zinc sheets from step (3) are placed on a 150°C flat plate heater and annealed for 1 h.

[0087] (5) Thickness improvement: The sample obtained in step (4) is subjected to spin coating-polymerization and bonding process 9 times to obtain composite zinc anode.

[0088] (6) Drying and storage: The composite zinc anode from step (5) is treated in a vacuum oven at 110°C for 12 h and then vacuum stored for later use.

[0089] In this embodiment, the preparation process of the zinc metal battery is as follows:

[0090] (1) The zinc-iodine cathode is prepared into a self-supporting thin film by roll forming process. The composite cathode is composed of zinc iodide, activated carbon, and polytetrafluoroethylene in a mass ratio of 50:40:10, wherein the areal loading of zinc iodide is 10~15 mg / cm³. 2 .

[0091] (2) The battery is assembled using a CR2032 button cell casing, a 304 stainless steel outer shell, gaskets, spring contacts, an electrolyte-wetted separator, and electrodes. Unless otherwise specified, a glass fiber membrane (thickness: 675 μm) is used as the separator, and a 2 M zinc sulfate aqueous solution is used as the electrolyte.

[0092] (3) In the full cell, bare zinc negative electrode Zn and composite zinc negative electrode PS1 / Zn were paired with zinc iodide-based positive electrode to construct control sample and target sample, respectively.

[0093] like Figure 8 The contact angle test results show that the contact angle of the 2 M zinc sulfate aqueous solution on the bare zinc (Zn) surface is 96.5°, while the contact angle on the fullerene-based polymer-modified PS1 surface increases to 114.3°. This indicates that the composite zinc anode has stronger hydrophobic properties, which not only helps to promote the desolvation process of hydrated zinc ions at the interface and improve deposition kinetics, but also effectively inhibits hydrogen evolution side reactions, slows down the corrosion and surface passivation of the zinc anode, thereby enhancing the cycle stability of the battery.

[0094] Figure 9 It was demonstrated at 200 mA g -1 A comparison of the cycle performance of aqueous zinc-iodine batteries based on zinc iodide cathodes was conducted at current densities, with discharge and charge cutoff voltages of 0.6 V and 1.6 V, respectively, and a test cycle count of 1000 cycles. The battery using a bare zinc anode had an initial discharge specific capacity of 137.55 mAh g⁻¹. -1 After 596 cycles, the concentration decreased to 99.41 mAh g. -1 The capacity retention rate was only 72%, which is close to the failure threshold of conventional batteries. This degradation is mainly due to zinc dendrite growth and the accompanying interfacial side reactions.

[0095] In contrast, the battery assembled using the composite zinc anode PS1 / Zn prepared by spray coating method has an initial discharge specific capacity of 138.83 mAh g. -1 After 1000 cycles, the specific capacity was 124.97 mAh g. -1， The retention rate was 90%, and the average capacity decay rate per cycle was 13.86 μAh g. -1 Compared to the thinner composite zinc anode in Example 1 (capacity retention of 95%), the electrochemical performance of this example showed a significant decrease due to the increased thickness of the modification layer. This result indicates that the thickness of the modification layer has a crucial impact on the anode performance: an excessively thick modification layer significantly prolongs the desolvation path of hydrated zinc ions, increases ion migration resistance, and thus deteriorates the kinetics of zinc deposition.

[0096] The advantage of this invention is that the thickness of the modified layer can be precisely controlled in the range of 10~1000nm by adjusting the liquid phase film formation process parameters, thereby avoiding the performance degradation problem caused by excessively thick modified layers and ensuring that the modified layer provides effective protection without impairing ion transport dynamics.

[0097] Table 1 Test results of Examples 1-3

[0098] Example Number of cycles <![CDATA[Initial specific capacity (mAh g -1 ).]]> <![CDATA[Specific capacity after cycling (mAh g -1 )]]> Example 1: Control Sample 553 137.73 99.92 Example 1 Target Sample 1000 142.69 135.59 Example 2 Control Sample 642 139.49 105.64 Example 2 Target Sample 1000 145.00 135.01 Example 3 Control Sample 596 137.55 99.41 Example 3 Target Sample 1000 138.83 124.97

[0099] According to the data in Table 1, based on the multiple functions of the fullerene carbon cage in electric field homogenization, Coulomb interaction, and hydrophobic regulation, the target samples prepared in Examples 1 to 3 can all be stably cycled for 1000 cycles, and the capacity retention rate after cycling is higher than 90%. In contrast, the control sample failed after a maximum of only 642 cycles due to the aggravation of side reactions, resulting in a short circuit and a capacity retention rate of only 75%.

[0100] This significant performance difference is primarily attributed to the integrated modification layer structure constructed through intermolecular polymerization and interfacial chemical bonding in this invention. Chemical bonding ensures a strong bond between the modification layer and the zinc substrate, preventing coating detachment caused by changes in electrode volume. Simultaneously, the three-dimensional cross-linked network formed by polymerization constructs continuous and uniform ion conduction channels without introducing heterogeneous components, thereby maintaining excellent interfacial stability and reaction kinetics during long-term cycling.

[0101] Furthermore, although both the target samples of Example 1 and Example 3 completed 1000 cycles, there was a difference of approximately 5% in capacity retention, indicating that the thickness of the modified layer has a significant impact on performance. It is worth emphasizing that the preparation method described in this invention can effectively control the thickness of the modified layer within the range of 10–1000 nm. This controllability is based on in-situ polymerization and bonding processes, ensuring that the modified layer maintains structural uniformity and interfacial stability at different thicknesses. This provides sufficient protection while reducing ion transport obstruction caused by excessive coating thickness.

[0102] In summary, this invention, through a synergistic strategy of polymerization and bonding, not only significantly improves the cycle life and electrochemical stability of the battery, but also achieves effective design and precise control of the modified layer structure, providing a reliable material basis for the development of high-performance aqueous zinc metal batteries.

Claims

1. A composite zinc anode constructed through self-assembly and in-situ polymerization, characterized in that, It consists of a bottom zinc metal layer and a top modification layer arranged sequentially from bottom to top; the bottom zinc metal layer is a zinc metal film; the top modification layer is a fullerene-based polymer film, and the two are connected by chemical bonding.

2. The composite zinc anode constructed by self-assembly and in-situ polymerization according to claim 1, characterized in that, The fullerene-based polymer film is a cross-linked network film obtained by intermolecular polymerization between fullerene molecules and chemical bonding between fullerene molecules and the bottom zinc metal.

3. The composite zinc anode constructed by self-assembly and in-situ polymerization according to claim 2, characterized in that, The fullerene-based molecule consists of a fullerene carbon cage portion, a bridging portion, and a terminal group portion, and its general structural formula is: wherein the fullerene carbon cage moiety is C 60 , C 70 , C 76 , C 78 , C 80 , C 84 one of; the bridging moiety is at least one of a chain, a cyclic structure; the end group moiety is at least one of a disulfide bond, a phosphoric monoester group, a phosphonic diester group, a functional group that can be intermolecularly polymerized and chemically bonded to a zinc substrate; n1 is any integer between 1 and 3; n2 is any integer between 1 and 30.

4. A method for preparing a composite zinc anode constructed by self-assembly and in-situ polymerization according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Dissolve the fullerene molecules in a selected solvent to obtain a fullerene molecule solution; Step 2: Cut the purchased zinc sheet into pieces. After ultrasonic cleaning in acetone, place the cut zinc sheet in isopropanol for later use. Step 3: Using a liquid phase film formation method, the fullerene-based molecular solution is coated onto the cleaned bottom zinc metal layer surface; Step 4: The coated bottom zinc metal layer is subjected to polymerization and bonding treatment to promote intermolecular polymerization of the fullerene molecular end groups or chemical bonding with the zinc substrate, forming a top fullerene polymer modification layer and obtaining a composite zinc anode.

5. The method for preparing a composite zinc anode constructed by self-assembly and in-situ polymerization according to claim 4, characterized in that, The selected solvent in step one is at least one of the aromatic solvents such as benzene, anisole, chlorobenzene, o-dichlorobenzene, and toluene.

6. The method for preparing a composite zinc anode constructed by self-assembly and in-situ polymerization according to claim 4, characterized in that, The concentration of the fullerene-based molecular solution in step one is 0.1~100 mg / mL.

7. The method for preparing a composite zinc anode constructed by self-assembly and in-situ polymerization according to claim 5, characterized in that, The thickness of the top fullerene-based polymer modification layer formed in step four is 10~1000 nm.

8. The method for preparing a composite zinc anode constructed by self-assembly and in-situ polymerization according to claim 5, characterized in that, The polymerization and bonding processes in step four are annealing processes.

9. The method for preparing a composite zinc anode constructed by self-assembly and in-situ polymerization according to claim 5, characterized in that, The polymerization and bonding processes in step four are radiation treatments.

10. The application of a composite zinc anode constructed by self-assembly and in-situ polymerization according to any one of claims 1 to 3 in an aqueous zinc metal battery.

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