A multi-level porous double-crosslinked single-ion gel polyelectrolyte, its preparation method and application, and an aqueous zinc metal battery.

Abstract

This invention relates to the field of electrochemical energy storage materials and aqueous zinc metal batteries, specifically to a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte, its preparation method and application, and aqueous zinc metal batteries. This hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte is prepared by photopolymerization using N-(hydroxymethyl)acrylamide and zinc 3-sulfopropyl acrylate as reactants, water as a solvent, and adding a double-crosslinking agent, polyethylene glycol diacrylate, and an initiator. This gel polyelectrolyte exhibits a mesoporous-macroporous hierarchical interconnected double-crosslinked network structure, achieving salt-free operation, single-ion conductivity, high ion transport efficiency, strong water retention, strong zinc dendrite suppression, and high mechanical strength, thus solving key technical challenges such as zinc dendrite growth, battery short circuits, and capacity decay. Applied to aqueous zinc metal batteries, it possesses excellent cycle stability, cycle life, and high-temperature stability, effectively adapting to applications such as large-scale energy storage, flexible electronics, and special safety power supplies.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage materials and aqueous zinc metal batteries, specifically to a multi-level porous double cross-linked single-ion gel polyelectrolyte, its preparation method and application, and aqueous zinc metal batteries. Background Technology

[0002] With the rapid iterative development of the renewable energy industry and flexible electronics technology, aqueous zinc metal batteries have become a core candidate battery system in the field of large-scale energy storage systems and wearable electronic devices due to their significant advantages such as high safety, low cost, high capacity and environmental friendliness. However, the traditional dual-ion gel electrolytes used in aqueous zinc metal batteries still suffer from three major technological bottlenecks, severely restricting their industrial application: First, the dual-ion conduction characteristics easily lead to concentration polarization problems. Specifically, during the free migration of anions in the electrolyte, they accumulate at the electrode interface, inducing zinc dendrite growth. When the zinc dendrites grow to a certain extent, they pierce the separator, ultimately causing the battery to short-circuit and fail. Second, to ensure the conductivity of the electrolyte, additional zinc salts (such as ZnSO4, ZnCl2, Zn(NO3)2, etc.) need to be added. These zinc salts themselves have limited solubility and are prone to salting out, which not only destroys the microscopic uniformity of the gel electrolyte but also exacerbates side reactions such as hydrogen evolution, zinc electrode corrosion, and passivation inside the battery, further reducing battery performance. Third, traditional gel electrolytes have poor water retention, weak mechanical properties, and insufficient structural stability. During long-term cycling, phenomena such as water evaporation and debonding of the electrolyte and electrode interface easily occur, leading to rapid capacity decay and making it difficult to meet the requirements of long battery life and large-scale use in practical applications.

[0003] To address the aforementioned technical bottlenecks, existing single-ion conductive electrolytes are mostly prepared using simple anion anchoring strategies. These strategies suffer from problems such as a simple network structure, weak intermolecular hydrogen bonding, disordered pore structure, and low ion transport efficiency, making it impossible to simultaneously achieve high conductivity and high Zn content. 2+ Despite the synergistic improvement in migration number, high mechanical strength, high water retention and long-term cycling stability, it is still difficult to solve the core defects of traditional gel electrolytes. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the first objective of this invention is to provide a method for preparing a hierarchical porous double cross-linked single-ion gel polyelectrolyte. This method is simple, has low production cost, and the preparation conditions are mild and controllable. It can form a network gel structure in situ without a template, making it easy to scale up production. Moreover, the prepared hierarchical porous double cross-linked single-ion gel polyelectrolyte can achieve a synergistic unity of six aspects: salt-free, single-ion conduction, high ion transport efficiency, strong water retention, strong zinc dendrite inhibition ability, and high mechanical strength, thereby solving key technical problems such as zinc dendrite growth, battery short circuit, and capacity decay.

[0005] To overcome the shortcomings of the prior art, the second objective of this invention is to provide a multi-level porous double cross-linked single-ion gel polyelectrolyte. This multi-level porous double cross-linked single-ion gel polyelectrolyte can achieve a synergistic unity of six aspects: salt-free, single-ion conduction, high ion transport efficiency, strong water retention, strong zinc dendrite suppression ability, and high mechanical strength, thereby solving key technical problems such as zinc dendrite growth, battery short circuit, and capacity decay.

[0006] The third objective of this invention is to provide an application of a multi-level porous, double-crosslinked, single-ion gel polyelectrolyte.

[0007] A fourth objective of this invention is to provide an aqueous zinc metal battery that has excellent cycle life and cycle stability.

[0008] To achieve the first objective of the invention, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a method for preparing a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte, comprising the following steps:

[0010] S1. Using N-(hydroxymethyl)acrylamide and zinc 3-sulfopropyl acrylate as reactants, and water as a solvent, a monomer solution is prepared. Then, a precursor solution is formed by adding the crosslinking agent polyethylene glycol diacrylate and an initiator.

[0011] S2. The precursor solution is converted into the multi-level porous double cross-linked single-ion gel polyelectrolyte by photopolymerization.

[0012] This invention discloses a method for preparing a multi-level porous, double-crosslinked, single-ion gel polyelectrolyte. The method utilizes two reactive monomers, N-(hydroxymethyl)acrylamide and zinc 3-sulfopropyl acrylate. After adding a double-crosslinking agent, polyethylene glycol diacrylate, and an initiator, a double-crosslinked network structure with mesoporous and macroporous hierarchical interconnections is constructed via photopolymerization. Specifically, the method utilizes the hydrophilic hydroxyl (-OH) and amide (-CONH2) groups provided by the reactive monomer N-(hydroxymethyl)acrylamide (N-MAM) to interact with the sulfonate (-SO3) groups of the reactive monomer zinc 3-sulfopropyl acrylate (SPA-Zn). - A multi-layered dynamic hydrogen bond network is formed, with anionic sulfonate groups covalently anchored to the polymer backbone, Zn 2+ As the main charge carriers, they form strong coordination with -O- and -N- on the polymer chain. The two reactive monomers construct multiple dynamic hydrogen bonds and coordination synergistic networks through intermolecular interactions, thereby achieving single-ion conduction in a salt-free system.

[0013] Among them, the number average molecular weight of the dual crosslinking agent polyethylene glycol diacrylate (PEGDA) is 400. Due to its short molecular chain and high double bond density, it can form a high crosslinking density, high mechanical strength, and dual crosslinking network. At the same time, it has excellent reactivity, fast curing rate, and high monomer conversion rate, effectively balancing mechanical strength, dimensional stability, and ion transport performance, while inhibiting excessive swelling of the system. It can provide a structurally stable, long-cycle, and highly safe crosslinking backbone for gel polyelectrolytes.

[0014] Further, in step S1, the molar ratio of N-(hydroxymethyl)acrylamide to zinc 3-sulfopropyl acrylate is (50~90):(10~50); wherein, by controlling the ratio of reactant monomers, the hydrogen bond network density and anion anchoring density in the polymer can be optimized, achieving the optimal match between ion conductivity, mechanical properties, and water retention properties. and / or

[0015] The amount of polyethylene glycol diacrylate used is 1.0wt% to 1.5wt% of the total mass of the reactants.

[0016] Further, in step S1, the initiator is lithium phenyl-2,4,6-trimethylbenzoylphosphonate; and / or

[0017] The amount of the initiator is 0.3wt% to 0.6wt% of the total mass of the reactants.

[0018] By adjusting the amounts of the aforementioned dual crosslinking agent polyethylene glycol diacrylate and photoinitiator, the polymerized hierarchical porous dual crosslinked monoionic gel polyelectrolyte can achieve a suitable crosslinking density, ensuring mechanical strength while realizing efficient ion transport; and ensuring that the photopolymerization reaction is complete, with no residual reactants, and the system exhibits excellent electrochemical stability.

[0019] Furthermore, in step S1, the solid content of the monomer solution is 8wt%~18wt%; and / or

[0020] The water is deionized water.

[0021] Further, in step S1, the precursor solution is prepared as follows: potassium 3-sulfopropyl acrylate and zinc hydroxide are dissolved in deionized water at a molar ratio of 2:1, and the mixture is stirred at 40℃~60℃ for 1.5h~2.5h to obtain an aqueous solution of zinc 3-sulfopropyl acrylate; N-(hydroxymethyl)acrylamide is added to the obtained aqueous solution of zinc 3-sulfopropyl acrylate to prepare a monomer solution, and a dual crosslinking agent, polyethylene glycol diacrylate, and an initiator are added to form a precursor solution; wherein, by adjusting the molar ratio of potassium 3-sulfopropyl acrylate to zinc hydroxide to 2:1, it is ensured that two sulfonate ions chelate one zinc ion to form a chemical structure as shown in Formula I.

[0022]

[0023] The stirring speed is 350 rpm to 450 rpm.

[0024] Furthermore, in step S2, the temperature of the photopolymerization reaction is 25℃~45℃, and the time of the photopolymerization reaction is 25min~45min; and / or

[0025] The photopolymerization reaction uses an ultraviolet LED light source, and / or the peak wavelength of the ultraviolet LED light source is 385nm.

[0026] This invention employs an ultraviolet LED light source with a peak wavelength of 385 nm and performs photopolymerization at a low temperature of 25℃~45℃ for 25min~45min. This avoids the problems of uneven network and easy degradation of molecular chains caused by local overheating in traditional thermal polymerization methods. It also significantly shortens the polymerization time and reduces energy consumption compared to traditional thermal polymerization methods, which typically take 2h~6h.

[0027] To achieve the second objective of the invention, the technical solution adopted by the present invention is as follows:

[0028] This invention provides a hierarchical porous double crosslinked single-ion gel polyelectrolyte, which is prepared by the above-described method for preparing a hierarchical porous double crosslinked single-ion gel polyelectrolyte.

[0029] Furthermore, the aforementioned hierarchical porous double crosslinked single-ion gel polyelectrolyte has a hierarchical porous structure, which includes mesopores with a pore size of 2nm to 5nm and macropores with a pore size of 1µm to 3µm.

[0030] To achieve the third objective of the invention, the technical solution adopted by the present invention is as follows:

[0031] This invention provides an application of a hierarchical porous double crosslinked single-ion gel polyelectrolyte, wherein the hierarchical porous double crosslinked single-ion gel polyelectrolyte prepared by the above-described method is used in aqueous zinc-based batteries, flexible energy storage devices, smart grid energy storage systems, wearable electronic devices, or special safety power supplies.

[0032] The aqueous zinc-based battery includes aqueous zinc metal battery, zinc-air battery, and zinc-iodine battery.

[0033] To achieve the fourth objective of the invention, the technical solution adopted by the present invention is as follows:

[0034] This invention provides an aqueous zinc metal battery, comprising the multi-level porous double-crosslinked single-ion gel polyelectrolyte described above, or the multi-level porous double-crosslinked single-ion gel polyelectrolyte prepared by the method described above; and / or

[0035] It also includes a positive electrode, a negative electrode, and a separator, wherein the hierarchical porous double cross-linked single-ion gel polyelectrolyte is composited with the separator to form an integrated structural layer; and / or

[0036] The positive electrode is zinc iodide, and the negative electrode is metallic zinc.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] (1) A method for preparing a hierarchical porous double crosslinked single-ion gel polyelectrolyte of the present invention uses N-(hydroxymethyl)acrylamide and zinc 3-sulfopropyl acrylate as reaction monomers, water as solvent to prepare a monomer solution, and adds a double crosslinking agent polyethylene glycol diacrylate and an initiator to carry out a photopolymerization reaction to prepare a hierarchical porous double crosslinked single-ion gel polyelectrolyte. This preparation method does not require a template and can form a network gel structure in situ, which is easy to scale up production. Moreover, the prepared hierarchical porous double crosslinked single-ion gel polyelectrolyte can achieve a synergistic unity of six aspects: salt-free, single-ion conduction, high ion transport efficiency, strong water retention, strong zinc dendrite inhibition ability and high mechanical strength, thereby solving key technical problems such as zinc dendrite growth, battery short circuit and capacity decay.

[0039] (2) The present invention provides a method for preparing a hierarchical porous double crosslinked single-ion gel polyelectrolyte. By employing photopolymerization to form a hierarchical porous double crosslinked single-ion gel polyelectrolyte from the precursor solution, it avoids the problems of local overheating leading to uneven network and easy degradation of molecular chains caused by traditional thermal polymerization. It also significantly shortens the polymerization time and reduces energy consumption compared to traditional thermal polymerization. Moreover, the preparation method is simple, has low production cost, mild and controllable preparation conditions, and is easy to scale up. Based on an aqueous reaction system, the entire preparation method is environmentally friendly.

[0040] (3) The multi-level porous double-crosslinked single-ion gel polyelectrolyte of the present invention can achieve intrinsically salt-free single-ion conduction. The sulfonate anions in the system are firmly anchored by covalent bonds, which can effectively suppress concentration polarization. At the same time, the multiple dynamic hydrogen bond network endows the electrolyte with excellent water retention properties, avoiding electrochemical performance degradation caused by gel dehydration. In addition, the Zn in the system 2+Coordination interactions with polymer segments significantly enhance the stability of the electrode-electrolyte interface and exhibit excellent inhibition of zinc dendrite growth. Through the synergistic integration of a salt-free system, single-ion conduction, high ion transport efficiency, excellent water retention, strong zinc dendrite suppression, and high mechanical strength, key technical bottlenecks in aqueous zinc metal batteries, such as uncontrolled zinc dendrite growth, susceptibility to short circuits, and cycle capacity decay, are fundamentally solved, effectively improving the overall cycle stability and safety performance of the battery.

[0041] (4) The multi-level porous double-crosslinked single-ion gel polyelectrolyte of the present invention has a multi-level porous structure, which includes mesopores with a pore size of 2nm~5nm and macropores with a pore size of 1µm~3µm. Its mesopore-macropore multi-level interconnected double-crosslinked network can construct continuous ion transport channels, effectively promoting Zn 2+ Rapid migration significantly enhances ionic conductivity, with a room temperature ionic conductivity of 21.2 mS / cm and a zinc ion transport number of 0.87. Through the synergistic effect of a double cross-linked network and a salt-free single-ion conduction mechanism, it achieves a comprehensive improvement in high ionic conductivity, high ion transport number, high water retention, excellent mechanical properties, long-term cycle stability, and high safety, providing reliable support for its industrial application in large-scale energy storage, wearable electronic devices, and other fields.

[0042] (5) An application of a multi-level porous double cross-linked single-ion gel polyelectrolyte of the present invention, which is used in aqueous zinc-based batteries, flexible energy storage devices, electrochemical energy storage systems, renewable energy storage systems, smart grid energy storage systems, wearable electronic devices or special safety power supplies, and is suitable for high-safety application scenarios such as large-scale energy storage systems. It adopts a salt-free system design and has the characteristics of no leakage, no salt precipitation and no zinc dendrite formation, which can meet the requirements of long cycle life and economic use.

[0043] (6) An aqueous zinc metal battery of the present invention, which adopts the multi-level porous double cross-linked single-ion gel polyelectrolyte of the present invention, has a capacity retention rate of not less than 93.5% after 500 cycles and a cycle life of more than 7000 hours. It has excellent cycle stability and cycle life, and can still maintain good stability in high temperature environment. It can effectively adapt to the usage requirements of different application scenarios, and its various performances are significantly better than those of traditional gel electrolyte systems. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a SEM image of the multi-level porous double cross-linked single-ion gel polyelectrolyte after freeze-drying according to Example 1 of the present invention at a magnification of 500x.

[0046] Figure 2 This is a graph showing the room temperature ionic conductivity test results of the multi-level porous double cross-linked single-ion gel polyelectrolyte of Example 1 of the present invention.

[0047] Figure 3 This is a graph showing the zinc ion transport number test results of the multi-level porous double cross-linked single-ion gel polyelectrolyte of Example 1 of the present invention.

[0048] Figure 4 This is a graph showing the room temperature ionic conductivity test results of the multi-level porous double cross-linked single-ion gel polyelectrolyte of Example 2 of the present invention.

[0049] Figure 5 This is a graph showing the zinc ion transport number test results of the multi-level porous double cross-linked single-ion gel polyelectrolyte of Example 2 of the present invention.

[0050] Figure 6 This is a graph showing the room temperature ionic conductivity test results of the multi-level porous double cross-linked single-ion gel polyelectrolyte of Example 3 of the present invention.

[0051] Figure 7 This is a graph showing the zinc ion transference number test results of the multi-level porous double cross-linked single-ion gel polyelectrolyte of Example 3 of the present invention.

[0052] Figure 8 This is the XRD pattern of the zinc anode of the multi-level porous double cross-linked single-ion gel polyelectrolyte assembled battery of Example 1 of the present invention after 24 hours of cycling.

[0053] Figure 9 This is a SEM image of the zinc negative electrode after 24 hours of cycling of the electrolyte assembled battery of Example 1 and Comparative Example 1 of the present invention.

[0054] Figure 10 This is a cycle performance curve of a zinc symmetric battery assembled with a multi-level porous double cross-linked single-ion gel polyelectrolyte according to Example 1 of the present invention.

[0055] Figure 11 This is a graph showing the results of the weight loss rate and water retention rate variation of the multi-level porous double cross-linked single-ion gel polyelectrolyte in the high-temperature stability test of Example 1 of the present invention.

[0056] Figure 12 This is a graph showing the test results of the compression deformation properties of the multi-level porous double cross-linked single-ion gel polyelectrolyte of Example 1 of the present invention.

[0057] Figure 13This is a graph showing the test results of the compression deformation properties of the single crosslinked gel polyelectrolyte system in Comparative Example 2 of this invention.

[0058] Figure 14 This is a SEM image of the multi-level porous double cross-linked single-ion gel polyelectrolyte after freeze-drying according to Example 1 of the present invention, at a magnification of 10,000. Detailed Implementation

[0059] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0060] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. In this invention, the singular forms “a,” “the,” and “the” as used in the embodiments and appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0061] In this embodiment of the invention, a method for preparing a multi-level porous double-crosslinked single-ion gel polyelectrolyte includes the following steps:

[0062] S1. Using N-(hydroxymethyl)acrylamide and zinc 3-sulfopropyl acrylate as reactants, and water as a solvent, a monomer solution is prepared. Then, a precursor solution is formed by adding the crosslinking agent polyethylene glycol diacrylate and an initiator.

[0063] S2. The precursor solution is converted into the multi-level porous double cross-linked single-ion gel polyelectrolyte by photopolymerization.

[0064] In some embodiments, in step S1, the molar ratio of N-(hydroxymethyl)acrylamide to zinc 3-sulfopropyl acrylate is (50~90):(10~50); and / or

[0065] The amount of polyethylene glycol diacrylate used is 1.0wt% to 1.5wt% of the total mass of the reactants.

[0066] In some embodiments, in step S1, the initiator is lithium phenyl-2,4,6-trimethylbenzoylphosphonate; and / or

[0067] The amount of the initiator is 0.3wt% to 0.6wt% of the total mass of the reactants.

[0068] In some embodiments, in step S1, the solid content of the monomer solution is 8wt%~18wt%; and / or

[0069] The water is deionized water.

[0070] In some embodiments, the precursor solution in step S1 is prepared as follows: potassium 3-sulfopropyl acrylate and zinc hydroxide are dissolved in deionized water at a molar ratio of 2:1, and the mixture is stirred at 40°C to 60°C for 1.5 to 2.5 hours to obtain an aqueous solution of zinc 3-sulfopropyl acrylate; N-(hydroxymethyl)acrylamide is added to the obtained aqueous solution of zinc 3-sulfopropyl acrylate to prepare a monomer solution, and a bicrosslinking agent, polyethylene glycol diacrylate, and an initiator are added to form a precursor solution; and / or

[0071] The stirring speed is 350 rpm to 450 rpm.

[0072] In some embodiments, in step S2, the temperature of the photopolymerization reaction is 25°C to 45°C, and the time of the photopolymerization reaction is 25 min to 45 min; and / or

[0073] The photopolymerization reaction uses an ultraviolet LED light source, and / or the peak wavelength of the ultraviolet LED light source is 385nm.

[0074] In this embodiment of the invention, a hierarchical porous double crosslinked single-ion gel polyelectrolyte is prepared by the above-described preparation method of a hierarchical porous double crosslinked single-ion gel polyelectrolyte.

[0075] The multi-level porous double cross-linked single-ion gel polyelectrolyte has a multi-level porous structure, which includes mesopores with a pore size of 2nm to 5nm and macropores with a pore size of 1µm to 3µm.

[0076] In this embodiment of the invention, an application of a hierarchical porous double cross-linked single-ion gel polyelectrolyte is described. The hierarchical porous double cross-linked single-ion gel polyelectrolyte prepared by the above-described method is used in aqueous zinc-based batteries, flexible energy storage devices, electrochemical energy storage systems, renewable energy storage systems, smart grid energy storage systems, wearable electronic devices, or special safety power supplies.

[0077] The aqueous zinc-based battery includes aqueous zinc metal battery, zinc-air battery, and zinc-iodine battery.

[0078] In this embodiment of the invention, an aqueous zinc metal battery comprises a hierarchical porous double-crosslinked single-ion gel polyelectrolyte as described above, or a hierarchical porous double-crosslinked single-ion gel polyelectrolyte prepared by the above-described method; and / or

[0079] It also includes a positive electrode, a negative electrode, and a separator, wherein the hierarchical porous double cross-linked single-ion gel polyelectrolyte is composited with the separator to form an integrated structural layer; and / or

[0080] The positive electrode is zinc iodide, and the negative electrode is metallic zinc.

[0081] The following description is based on specific embodiments. Example 1

[0082] A method for preparing a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte includes the following steps:

[0083] S1. Potassium 3-sulfopropyl acrylate (SPA) and zinc hydroxide were dissolved in deionized water at a molar ratio of 2:1 and stirred at 50°C and 400 rpm for 2 hours to obtain an aqueous solution of zinc 3-sulfopropyl acrylate (SPA-Zn). Then, N-(hydroxymethyl)acrylamide (N-MAM) was added to prepare a monomer solution with a solid content of 12 wt%. A precursor solution was formed by adding the crosslinking agent polyethylene glycol diacrylate (PEGDA) and the initiator lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) and stirring. In this embodiment, the molar ratio of the reactant monomer N-(hydroxymethyl)acrylamide to zinc 3-sulfopropyl acrylate was 70:30; the amount of polyethylene glycol diacrylate was 1.2 wt% of the total mass of the reactants; and the amount of lithium phenyl-2,4,6-trimethylbenzoylphosphonate was 0.4 wt% of the total mass of the reactants.

[0084] S2. Under the condition of ultraviolet LED light source with a peak wavelength of 385 nm, the precursor solution is subjected to photopolymerization reaction at 35°C for 30 min to form a multi-level porous double cross-linked single ion gel polyelectrolyte (denoted as MZ30).

[0085] The multi-level porous double cross-linked single-ion gel polyelectrolyte prepared in this embodiment has a multi-level porous structure, which includes mesopores with a pore size of 2nm~5nm and macropores with a pore size of 1µm~3µm. Example 2

[0086] A method for preparing a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte includes the following steps:

[0087] S1. Potassium 3-sulfopropyl acrylate (SPA) and zinc hydroxide were dissolved in deionized water at a molar ratio of 2:1 and stirred at 50°C and 400 rpm for 2 hours to obtain an aqueous solution of zinc 3-sulfopropyl acrylate (SPA-Zn). Then, N-(hydroxymethyl)acrylamide (N-MAM) was added to prepare a monomer solution with a solid content of 16 wt%. A precursor solution was formed by adding the crosslinking agent polyethylene glycol diacrylate (PEGDA) and the initiator lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) and stirring. In this embodiment, the molar ratio of the reactant monomer N-(hydroxymethyl)acrylamide to zinc 3-sulfopropyl acrylate was 90:10; the amount of polyethylene glycol diacrylate was 1.2 wt% of the total mass of the reactants; and the amount of lithium phenyl-2,4,6-trimethylbenzoylphosphonate was 0.4 wt% of the total mass of the reactants.

[0088] S2. Under the condition of ultraviolet LED light source with a peak wavelength of 385 nm, the precursor solution is subjected to photopolymerization reaction at 25°C for 35 min to form a multi-level porous double cross-linked single ion gel polyelectrolyte (denoted as MZ10).

[0089] The multi-level porous double cross-linked single-ion gel polyelectrolyte prepared in this embodiment has a multi-level porous structure, which includes mesopores with a pore size of 2nm~5nm and macropores with a pore size of 1µm~3µm. Example 3

[0090] A method for preparing a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte includes the following steps:

[0091] S1. Potassium 3-sulfopropyl acrylate (SPA) and zinc hydroxide were dissolved in deionized water at a molar ratio of 2:1 and stirred at 50°C and 400 rpm for 2 hours to obtain an aqueous solution of zinc 3-sulfopropyl acrylate (SPA-Zn). Then, N-(hydroxymethyl)acrylamide (N-MAM) was added to prepare a monomer solution with a solid content of 10 wt%. A precursor solution was formed by adding the crosslinking agent polyethylene glycol diacrylate (PEGDA) and the initiator lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) and stirring. In this embodiment, the molar ratio of the reactant monomer N-(hydroxymethyl)acrylamide to zinc 3-sulfopropyl acrylate was 50:50; the amount of polyethylene glycol diacrylate was 1.2 wt% of the total mass of the reactants; and the amount of lithium phenyl-2,4,6-trimethylbenzoylphosphonate was 0.4 wt% of the total mass of the reactants.

[0092] S2. Under the condition of ultraviolet LED light source with a peak wavelength of 385 nm, the precursor solution is subjected to photopolymerization reaction at 40℃ for 28 min to form a multi-level porous double cross-linked single ion gel polyelectrolyte (denoted as MZ50).

[0093] The multi-level porous double cross-linked single-ion gel polyelectrolyte prepared in this embodiment has a multi-level porous structure, which includes mesopores with a pore size of 2nm~5nm and macropores with a pore size of 1µm~3µm. Example 4

[0094] A method for preparing a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte includes the following steps:

[0095] S1. Potassium 3-sulfopropyl acrylate (SPA) and zinc hydroxide were dissolved in deionized water at a molar ratio of 2:1 and stirred at 40°C and 450 rpm for 2.5 h to obtain an aqueous solution of zinc 3-sulfopropyl acrylate (SPA-Zn). Then, N-(hydroxymethyl)acrylamide (N-MAM) was added to prepare a monomer solution with a solid content of 8 wt%. A precursor solution was formed by adding the crosslinking agent polyethylene glycol diacrylate (PEGDA) and the initiator lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) and stirring. In this embodiment, the molar ratio of the reactant monomer N-(hydroxymethyl)acrylamide to zinc 3-sulfopropyl acrylate was 60:40; the amount of polyethylene glycol diacrylate was 1.0 wt% of the total mass of the reactants; and the amount of lithium phenyl-2,4,6-trimethylbenzoylphosphonate was 0.3 wt% of the total mass of the reactants.

[0096] S2. Under the condition of ultraviolet LED light source with a peak wavelength of 385 nm, the precursor solution is subjected to photopolymerization reaction at 25°C for 45 min to form a multi-level porous double cross-linked single-ion gel polyelectrolyte.

[0097] The multi-level porous double cross-linked single-ion gel polyelectrolyte prepared in this embodiment has a multi-level porous structure, which includes mesopores with a pore size of 2nm~5nm and macropores with a pore size of 1µm~3µm. Example 5

[0098] A method for preparing a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte includes the following steps:

[0099] S1. Potassium 3-sulfopropyl acrylate (SPA) and zinc hydroxide were dissolved in deionized water at a molar ratio of 2:1 and stirred at 60°C and 350 rpm for 1.5 h to obtain an aqueous solution of zinc 3-sulfopropyl acrylate (SPA-Zn). Then, N-(hydroxymethyl)acrylamide (N-MAM) was added to prepare a monomer solution with a solid content of 18 wt%. A precursor solution was formed by adding the crosslinking agent polyethylene glycol diacrylate (PEGDA) and the initiator lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) and stirring. In this embodiment, the molar ratio of the reactant N-(hydroxymethyl)acrylamide to zinc 3-sulfopropyl acrylate was 80:20; the amount of polyethylene glycol diacrylate was 1.5 wt% of the total mass of the reactants; and the amount of lithium phenyl-2,4,6-trimethylbenzoylphosphonate was 0.6 wt% of the total mass of the reactants.

[0100] S2. Under the condition of ultraviolet LED light source with a peak wavelength of 385 nm, the precursor solution is subjected to photopolymerization reaction at 45°C for 25 min to form a multi-level porous double cross-linked single-ion gel polyelectrolyte.

[0101] The multi-level porous double cross-linked single-ion gel polyelectrolyte prepared in this embodiment has a multi-level porous structure, which includes mesopores with a pore size of 2nm~5nm and macropores with a pore size of 1µm~3µm. Example 6

[0102] Application of a hierarchical porous double crosslinked single-ion gel polyelectrolyte: Application of any one of the hierarchical porous double crosslinked single-ion gel polyelectrolytes in aqueous zinc-based batteries, flexible energy storage devices, electrochemical energy storage systems, renewable energy storage systems, smart grid energy storage systems, wearable electronic devices, or special safety power supplies in Examples 1 to 5.

[0103] Among them, aqueous zinc-based batteries include aqueous zinc metal batteries, zinc-air batteries, and zinc-iodine batteries. Example 7

[0104] An aqueous zinc metal battery includes any one of the multi-level porous double cross-linked single-ion gel polyelectrolytes from Examples 1 to 5, and further includes a positive electrode, a negative electrode, and a separator. The multi-level porous double cross-linked single-ion gel polyelectrolytes and the separator are composited to form an integrated structural layer; the positive electrode is zinc iodide, and the negative electrode is metallic zinc.

[0105] In the process of preparing aqueous zinc metal batteries, the precursor solution is fully impregnated into the separator and a uniform liquid film is formed on its surface. Then, a photopolymerization reaction is carried out in situ to form a hierarchical porous double cross-linked single-ion gel polyelectrolyte, and the hierarchical porous double cross-linked single-ion gel polyelectrolyte is combined with the separator to form an integrated structural layer.

[0106] Comparative Example 1

[0107] The preparation method of the conventional zinc salt immersion gel electrolyte differs from Example 1 in that, in this comparative example, sodium 3-sulfopropyl acrylate (SPA-Na) is used instead of zinc 3-sulfopropyl acrylate (SPA-Zn) as the reactive monomer. The gel electrolyte is prepared by photopolymerization with the reactive monomer N-(hydroxymethyl)acrylamide (N-MAM). The prepared gel electrolyte is then immersed in a 1M ZnSO4 solution for 24 hours before being removed, thus obtaining the conventional zinc salt immersion gel electrolyte. All other preparation methods are the same as in Example 1.

[0108] Comparative Example 2

[0109] A method for preparing a single-crosslinked gel polyelectrolyte is disclosed. The difference between this comparative example and Example 1 is that the single crosslinking agent N,N'-methylenebisacrylamide is used instead of the dual crosslinking agent polyethylene glycol diacrylate (PEGDA) in this comparative example. All other preparation methods are the same as in Example 1, resulting in a single-crosslinked gel polyelectrolyte.

[0110] Structural morphology characterization

[0111] (I) Morphological characterization by scanning electron microscopy

[0112] The hierarchical porous double-crosslinked single-ion gel polyelectrolyte (MZ30) prepared in Example 1 was freeze-dried at -20°C for 10 h, and its morphology was characterized by scanning electron microscopy (SEM). Figure 1 and Figure 14 As shown.

[0113] Depend on Figure 1 and Figure 14 As can be seen, the multi-level porous double-crosslinked single-ion gel polyelectrolyte prepared by this invention has a mesoporous-macroporous multi-level interconnected double-crosslinked network structure, wherein the macropore size is controlled at 1μm to 3μm, the mesopore size is 2nm to 5nm, and the channels are interconnected and continuously distributed, thus providing a reliable structural basis for rapid ion transport and stable moisture retention. In addition, this mesoporous-macroporous multi-level interconnected double-crosslinked network structure can also limit the lateral growth of dendrites and prevent them from piercing the membrane.

[0114] Performance testing

[0115] (a) Room temperature ionic conductivity and zinc ion transport number test of gel polyelectrolytes

[0116] The hierarchical porous double cross-linked single-ion gel polyelectrolytes prepared in Examples 1 to 3 were used to assemble SS|SPE|SS blocking batteries, and room temperature ionic conductivity and zinc ion transport number were tested.

[0117] The room-temperature ionic conductivity was measured using electrochemical impedance spectroscopy (EIS) in an SS|SPE|SS blocked cell (SS being a stainless steel electrode and SPE being a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte). The zinc ion transport number (tZn) was also measured. 2+ The determination was performed using the Bruce-Vincent method.

[0118] The room temperature ionic conductivity test results of the multi-level porous double-crosslinked single-ion gel polyelectrolyte (MZ30) in Example 1 are shown in the figure below. Figure 2 As shown in the figure. The zinc ion transport number test results for MZ30 in Example 1 are shown in the figure. Figure 3 As shown.

[0119] The room temperature ionic conductivity test results of the multi-level porous double-crosslinked single-ion gel polyelectrolyte (MZ10) in Example 2 are shown in the figure below. Figure 4 As shown in the figure. The zinc ion transport number test results for MZ10 in Example 1 are shown in the figure. Figure 5 As shown.

[0120] The room temperature ionic conductivity test results of the multi-level porous double-crosslinked single-ion gel polyelectrolyte (MZ50) in Example 3 are shown in the figure below. Figure 6 As shown in the figure. The zinc ion transport number test results for MZ50 in Example 1 are shown in the figure. Figure 7 As shown.

[0121] Depend on Figure 2 As can be seen, the room temperature ionic conductivity of the MZ30 assembled battery in Example 1 reaches 21.2 mS / cm, which is attributed to its multi-level interconnected pore structure, providing Zn with a high conductivity. 2+ A continuous and efficient ion transport channel was constructed, thereby significantly improving ion conduction performance. Figure 3 It can be seen that the Zn in the MZ30 system of Example 1 2+ The high mobility number of 0.87 indicates that the anions in the system are effectively anchored, achieving highly selective single-ion conduction and significantly suppressing concentration polarization.

[0122] Depend on Figure 4 As can be seen, the room temperature ionic conductivity of the MZ10 assembled battery in Example 2 is 16.59 mS / cm, which is slightly lower than that of the MZ30 in Example 1. Figure 5 It can be seen that the Zn in the MZ10 system 2+The migration number was 0.65, slightly lower than that of Example 1. This is because the proportion of the reactive monomer 3-sulfopropyl acrylate zinc salt (SPA-Zn) in Example 2 was lower than that in Example 1, resulting in a lower sulfonate anchoring density. Consequently, the room temperature ionic conductivity and Zn2+ migration number decreased slightly, but were still higher than those of conventional dual-ion gel electrolytes. In addition, the relatively lower sulfonate anchoring density of MZ10 in Example 2 made it more flexible than that of Example 1, making it more suitable for the application scenarios of flexible electronic devices.

[0123] Depend on Figure 6 and 7 As can be seen, the room temperature ionic conductivity of the MZ50 assembled battery in Example 3 is 14.5 mS / cm, and the Zn... 2+ The migration number was 0.56. This result indicates that a relatively higher proportion of the reactive monomer zinc 3-sulfopropyl acrylate (SPA-Zn) in the MZ50 system resulted in the highest anion anchoring density, strong ion-selective transport capability, and outstanding suppression of concentration polarization. Simultaneously, its cross-linked network structure was more compact, and the ion transport channels were more regular and orderly. Therefore, its room temperature ionic conductivity was slightly lower than that of Examples 1 and 2, making it more suitable for applications requiring high stability and long cycle life.

[0124] (II) Full battery cycle performance test

[0125] A full cell was assembled using the hierarchical porous double-crosslinked single-ion gel polyelectrolyte (MZ30) of Example 1 and the conventional zinc salt immersion gel electrolyte of Comparative Example 1. The positive electrode of the cell was zinc iodide, the negative electrode was zinc foil, and the cell had no separator. The full cell cycle performance was then tested under the following conditions: room temperature, 0.5C charge / discharge rate, and a voltage window of 1.0V to 1.8V.

[0126] For a comparison of the room temperature ionic conductivity, zinc ion transport number, and cycle life of Example 1 and Comparative Example 1, please refer to Table 1.

[0127] Table 1. Comparison of Cyclic Performance between Example 1 and Comparative Example 1

[0128]

[0129] As shown in Table 1, the hierarchical porous double-crosslinked single-ion gel polyelectrolyte prepared in this invention exhibits significantly improved room-temperature ionic conductivity compared to traditional zinc salt-immersed gel electrolytes. -2 The migration number was also significantly improved. Meanwhile, the full cell assembled using the hierarchical porous dual-crosslinked single-ion gel polyelectrolyte of this invention achieved stable cycling for over 7000 hours, while the cycle life of Comparative Example 1 was less than 500 hours, demonstrating that the hierarchical porous dual-crosslinked single-ion gel polyelectrolyte of this invention significantly improves the cycle stability of the battery.

[0130] Furthermore, the multi-level porous double-crosslinked single-ion gel polyelectrolyte assembled full cell of Example 1 exhibited an initial discharge capacity of 211 mAh / g at room temperature and a charge / discharge rate of 0.5C. After 500 cycles, the capacity retention rate was as high as 93.5%. In addition, the assembled battery achieved a coulombic efficiency of 99.5%, and its capacity retention rate remained above 80% after 3000 charge / discharge cycles. Under 28 days of rest, the battery self-discharge rate was as low as 3.7%, demonstrating excellent long-cycle stability and superior storage performance.

[0131] In addition, the multi-level porous double-crosslinked single-ion gel polyelectrolyte assembled full cell of Example 1, under room temperature and 0.5C charge-discharge rate conditions, had an initial discharge capacity of 211 mAh / g. After 24 hours of cycling, X-ray diffraction analysis was performed on the zinc anode. The test results are as follows: Figure 8 As shown.

[0132] Depend on Figure 8 As can be seen, after 24 hours of cycling, the XRD pattern of the zinc anode showed no impurity phase diffraction peaks, and the intensity ratio of the diffraction peaks of the zinc deposition crystal plane (002) and (101) remained stable. This indicates that no by-products were generated during the cycling process, the zinc ion deposition was uniform and dense, and the side reactions such as hydrogen evolution, passivation and corrosion were effectively suppressed.

[0133] In addition, for the multi-level porous double-crosslinked single-ion gel polyelectrolyte of Example 1 and the conventional zinc salt immersion gel electrolyte of Comparative Example 1, after 24 hours of cycling at room temperature and 0.5C charge-discharge rate, the morphology of the zinc anode was characterized by scanning electron microscopy (SEM). Figure 9 As shown.

[0134] Depend on Figure 9 As can be seen, after 24 hours of cycling, the zinc anode surface of the battery assembled using the conventional zinc salt immersion gel electrolyte of Comparative Example 1 showed obvious zinc dendrites and local protrusions; while the zinc anode surface of the battery assembled using the multi-level porous double cross-linked single-ion gel polyelectrolyte of this invention remained smooth and dense under the same cycling conditions, without obvious dendrite formation or corrosion pit defects. These results confirm that the present invention, through the synergistic effect of the anionic sulfonate provided by the reactive monomer zinc 3-sulfopropyl acrylate and the interfacial coordination effect, can significantly inhibit the nucleation and growth of zinc dendrites.

[0135] (III) Cyclic performance test of zinc symmetric battery

[0136] The hierarchical porous double crosslinked single-ion gel polyelectrolyte (MZ30) prepared in Example 1 was used to assemble a zinc symmetric cell (Zn|SPE|Zn) at a current density of 1 mA·cm⁻¹.-2 The surface capacity is 1 mAh·cm -2 The cycle performance of the zinc symmetric battery was tested under the specified test conditions, and the test results are as follows: Figure 10 As shown.

[0137] Depend on Figure 10 As can be seen, the zinc symmetric battery assembled using the hierarchical porous double crosslinked single-ion gel polyelectrolyte (MZ30) of this invention achieves a current density of 1 mA·cm⁻² and an areal capacity of 1 mAh·cm⁻². -2 Under constant current cycling conditions, it can operate stably for 7000 hours without short circuit, demonstrating excellent long-cycle stability and interface reliability, and possessing great potential for industrial applications.

[0138] (iv) High-temperature stability test of gel polyelectrolytes

[0139] The multi-level porous double cross-linked single-ion gel polyelectrolyte (MZ30) prepared in Example 1 and the single cross-linked system gel polyelectrolyte in Comparative Example 2 were subjected to high-temperature stability tests. The test conditions were storage at 60°C for 10 days.

[0140] In Example 1, after the high-temperature stability test of MZ30, the changes in the weight loss rate and water retention rate of MZ30 were as follows: Figure 11 As shown. By Figure 11 As can be seen, after 10 days of high-temperature testing, MZ30 exhibited a weight loss rate of only 2.9% and a water retention rate of 97.1%, significantly higher than the water retention rate (around 15%) of the single-crosslinked gel polyelectrolyte in Comparative Example 2. Furthermore, after 10 days of high-temperature testing, MZ30 maintained a room-temperature ionic conductivity of up to 91.3%. This demonstrates that the hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte of this invention possesses the potential for stable application in high-temperature environments, exhibiting excellent thermal stability and structural water retention capacity.

[0141] (v) Test of compressive deformation properties of gel polyelectrolytes

[0142] The multi-level porous double-crosslinked single-ion gel polyelectrolyte (MZ30) prepared in Example 1 and the single-crosslinked gel polyelectrolyte system of Comparative Example 2 were subjected to compression deformation performance tests. A pressure of 5 kN was applied under sensor conditions, and the test results are as follows: Figure 12 and Figure 13 As shown.

[0143] Depend on Figure 12 and Figure 13As can be seen, the single cross-linked gel polyelectrolyte of Comparative Example 2 broke when the deformation reached 41.1%, indicating poor mechanical strength and difficulty in adapting to application scenarios with external impact and collision. In contrast, the multi-level porous double cross-linked single-ion gel polyelectrolyte of the present invention can withstand a deformation of up to 60.32% while maintaining structural integrity, exhibiting excellent mechanical strength and structural stability, and is suitable for complex usage environments that are susceptible to external impact.

[0144] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a hierarchical porous, double-crosslinked, single-ion gel polyelectrolyte, characterized in that, Includes the following steps: S1. Using N-(hydroxymethyl)acrylamide and zinc 3-sulfopropyl acrylate as reactants, and water as a solvent, a monomer solution is prepared. Then, a precursor solution is formed by adding the crosslinking agent polyethylene glycol diacrylate and the initiator. S2. The precursor solution is formed into the hierarchical porous double cross-linked single-ion gel polyelectrolyte by photopolymerization reaction; In step S1, the precursor solution is prepared as follows: 3-sulfopropylacrylic acid and zinc hydroxide are reacted in deionized water at a molar ratio of 2:1 at 40℃~60℃ for 1.5h~2.5h to obtain an aqueous solution of zinc 3-sulfopropylacrylic acid; N-(hydroxymethyl)acrylamide is added to the obtained aqueous solution of zinc 3-sulfopropylacrylic acid to prepare a monomer solution, and a bicrosslinking agent, polyethylene glycol diacrylate, and an initiator are added to form a precursor solution; In step S1, the molar ratio of N-(hydroxymethyl)acrylamide to zinc 3-sulfopropyl acrylate is (50~90):(10~50); the amount of polyethylene glycol diacrylate used is 1.0wt%~1.5wt% of the total mass of the reactants; the solid content of the monomer solution is 8wt%~18wt%. In step S2, the temperature of the photopolymerization reaction is 25℃~45℃, and the time of the photopolymerization reaction is 25min~45min; The hierarchical porous double crosslinked single-ion gel polyelectrolyte has a hierarchical porous structure, which includes mesopores with a pore size of 2nm to 5nm and macropores with a pore size of 1µm to 3µm.

2. The method for preparing a hierarchical porous double-crosslinked single-ion gel polyelectrolyte as described in claim 1, characterized in that, In step S1, the initiator is lithium phenyl-2,4,6-trimethylbenzoylphosphonate; and / or The amount of the initiator is 0.3wt% to 0.6wt% of the total mass of the reactants.

3. The method for preparing a hierarchical porous double-crosslinked single-ion gel polyelectrolyte as described in claim 1, characterized in that, In step S1, the water is deionized water.

4. The method for preparing a hierarchical porous double-crosslinked single-ion gel polyelectrolyte as described in claim 1, characterized in that, In step S1, the stirring rate is 350 rpm to 450 rpm.

5. The method for preparing a hierarchical porous double-crosslinked single-ion gel polyelectrolyte as described in claim 1, characterized in that, In step S2, the photopolymerization reaction uses an ultraviolet LED light source, and / or the peak wavelength of the ultraviolet LED light source is 385 nm.

6. An application of a multi-level porous, double-crosslinked, single-ion gel polyelectrolyte, characterized in that, The multi-level porous double cross-linked single-ion gel polyelectrolyte prepared by the method of any one of claims 1 to 5 can be used in aqueous zinc-based batteries, flexible energy storage devices, electrochemical energy storage systems, renewable energy storage systems, smart grid energy storage systems, wearable electronic devices, or special safety power supplies. The aqueous zinc-based battery includes aqueous zinc metal battery, zinc-air battery, and zinc-iodine battery.

7. An aqueous zinc metal battery, characterized in that, The multi-level porous double-crosslinked single-ion gel polyelectrolyte prepared by the preparation method of the multi-level porous double-crosslinked single-ion gel polyelectrolyte according to any one of claims 1 to 5; It also includes a positive electrode, a negative electrode, and a separator, wherein the multi-level porous double cross-linked single-ion gel polyelectrolyte and the separator are combined to form an integrated structural layer; The positive electrode is zinc iodide, and the negative electrode is metallic zinc.

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