A dual-network gel electrolyte and a preparation method and application thereof

Abstract

This invention belongs to the field of battery technology, specifically relating to a dual-network gel electrolyte, its preparation method, and its application. The raw materials of the dual-network gel electrolyte include a first polymer, a second polymer, a metal salt, a plasticizer, a crosslinking agent, and a solvent. The first polymer forms a flexible first network through chemical crosslinking, serving as the main channel for ion transport to ensure high ionic conductivity. Simultaneously, the second polymer is introduced, interpenetrating with the first network through physical or chemical interactions to form a second network. This structure, through synergistic action, preferentially causes reversible damage to the second network to dissipate energy when subjected to external forces (such as zinc dendrite growth stress), thereby protecting the integrity of the main chain structure and ion channels of the first network. Ultimately, the gel achieves excellent mechanical properties such as high toughness and puncture resistance while maintaining high ionic conductivity and excellent capacity retention, solving the problem of mutual constraint between the two in traditional solutions.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a dual-network gel electrolyte, its preparation method, and its application. Background Technology

[0002] Aqueous zinc-ion batteries are highly safe, low-cost, and environmentally friendly, with the zinc anode possessing extremely high theoretical capacity and appropriate redox potential, making them a promising candidate for next-generation large-scale energy storage systems.

[0003] However, commercial applications still face significant challenges. Specifically, liquid aqueous electrolytes are prone to leakage and evaporation, and can easily lead to uncontrolled dendrite growth, hydrogen evolution, and corrosion side reactions on the zinc anode, resulting in rapid capacity decay and short-circuit risks.

[0004] Gel electrolytes are considered an ideal solution to the aforementioned problems, combining the dimensional stability of solids with the high ionic conductivity of liquids. Among them, gel electrolytes based on natural polymer gelatin have attracted much attention due to their excellent biocompatibility, biodegradability, and abundant functional groups.

[0005] However, a single gelatin network typically lacks sufficient mechanical properties (such as strength and toughness), and has shortcomings in suppressing zinc dendrite penetration and adapting to long-term cycling stress in batteries. In the prior art, although there have been attempts to enhance gelatin gels through physical blending or simple cross-linking, the improvement in mechanical properties is often limited, and often at the cost of sacrificing ionic conductivity, making it difficult to maintain long-term stability at the dynamically changing zinc deposition / stripping interface. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of existing dual-network gel electrolytes that cannot simultaneously achieve mechanical and electrical properties, thereby providing a dual-network gel electrolyte, its preparation method and application.

[0007] Therefore, the present invention provides the following technical solution: The first aspect of this invention protects a dual-network gel electrolyte, wherein the raw materials of the dual-network gel electrolyte include a first polymer, a second polymer, a metal salt, a plasticizer, a crosslinking agent, and a solvent.

[0008] In one optional embodiment, the mass ratio of the first polymer to the second polymer is 1:(0.1-1). For example, the mass ratio of the first polymer to the second polymer can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, or within any of the above values; optionally, it can be 1:(0.4-0.8).

[0009] In one alternative embodiment, the first polymer includes at least one of gelatin, agar, and hyaluronic acid.

[0010] In one alternative embodiment, the second polymer includes at least one of polyvinyl alcohol, sodium alginate, polyacrylamide, cellulose nanofibers, chitosan, and polyacrylic acid.

[0011] In this invention, the cellulose nanofibers can be modified, for example, by carboxylation or hydroxylation. The modification can be performed according to the actual situation, or the modified cellulose nanofibers can be purchased directly. Typically, without limitation, the carboxylated cellulose nanofibers are purchased from Xianfeng Nano, with an average diameter of 6.0 nm and an average length of 2.5 μm.

[0012] In one optional embodiment, the mass ratio of the first polymer to the metal salt is 1:(0.1-5). For example, the mass ratio of the first polymer to the metal salt can be 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, or within any of the above values; optionally, it can be 1:(1-3).

[0013] In one optional embodiment, the metal salt includes at least one of lithium salt, sodium salt, and zinc salt; optionally, it includes at least one of zinc trifluoromethanesulfonate, zinc sulfate, zinc acetate, zinc chloride, zinc nitrate, and zinc perchlorate.

[0014] In one optional embodiment, the mass ratio of the first polymer to the plasticizer is 1:(0.5-3). For example, the mass ratio of the first polymer to the plasticizer can be 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, or within any of the above values, and can be selected as 1:(1.25-3).

[0015] In one alternative embodiment, the plasticizer includes at least one of glycerol, ethylene glycol, polyethylene glycol, and 1-ethyl-3-methylimidazolium acetate.

[0016] In one alternative embodiment, the crosslinking agent includes crosslinking agent A and optionally crosslinking agent B.

[0017] In one optional embodiment, the mass ratio of the first polymer to crosslinking agent A is 1:(0.01-0.05). As an example, the mass ratio of the first polymer to crosslinking agent A can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, or within any of the above values, and can be selected as 1:(0.02-0.04).

[0018] In one alternative embodiment, the crosslinking agent A includes at least one of genipin, glutaraldehyde, glyoxal, epichlorohydrin, and citric acid.

[0019] In one optional embodiment, the crosslinking agent B comprises multivalent metal ions; optionally, it comprises zinc ions and / or manganese ions, and when added, a metal salt containing the corresponding metal ions is added.

[0020] In one optional embodiment of the present invention, the solvent includes at least one of water, ethanol, methanol, and acetone.

[0021] In one alternative embodiment, the mass ratio of the first polymer to the solvent is 1:(5-15). For example, the mass ratio of the first polymer to the solvent can be 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, or within any of the above values.

[0022] A second aspect of this invention protects a method for preparing the aforementioned dual-network gel electrolyte, wherein the preparation method comprises the following steps: S1, mix the first polymer, the second polymer, the metal salt, the plasticizer, and the solvent to obtain the precursor solution; S2, the precursor solution and crosslinking agent are mixed and gelled to obtain a dual-network gel electrolyte.

[0023] In one optional embodiment, in step S1, the first polymer and a portion of the solvent are first mixed to obtain solution A; the second polymer and the remaining solvent are second mixed to obtain solution B; solutions A and B are combined, and a metal salt and a plasticizer are added for a third mixing to obtain a precursor solution; firstly, the first polymer and the second polymer are fully dissolved to form a homogeneous solution, and then the metal salt and plasticizer are introduced to ensure that the ion carrier and plasticizing components are uniformly dispersed, avoiding component agglomeration or insufficient dissolution.

[0024] In one optional implementation, the temperature of the first mixing is 40-60°C. For example, the temperature of the first mixing can be 40°C, 45°C, 50°C, 55°C, 60°C, or any of the above values; the time is 5-8 hours. For example, the time of the first mixing can be 5 hours, 6 hours, 7 hours, 8 hours, or any of the above values.

[0025] In one optional implementation, the temperature of the second mixing is 80-98°C. For example, the temperature of the second mixing can be 80°C, 85°C, 90°C, 95°C, 98°C, or within any range of the above values; the time is 5-8 hours. For example, the time of the second mixing can be 5 hours, 6 hours, 7 hours, 8 hours, or within any range of the above values.

[0026] In one optional embodiment, the temperature of the third mixing is 40-60°C. For example, the temperature of the third mixing can be 40°C, 45°C, 50°C, 55°C, 60°C, or within any range of the above values; the time is 1-5 hours. For example, the time of the third mixing can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or within any range of the above values.

[0027] In one optional embodiment, the gelation treatment includes a settling step; the settling step mainly relies on the chemical reaction between the crosslinking agent and the active groups on the polymer chain to gradually connect the polymer chains to form a preliminary network structure, thereby realizing the transformation of the precursor liquid from a liquid state to a gel state.

[0028] In this invention, the settling is a conventional condition in the art. Typically, without limitation, it is settling at room temperature (20-25°C) for 4-24 hours. The setting time can be selected according to the actual situation. If other steps are performed, the settling time can be appropriately shortened.

[0029] In one optional embodiment, the gelation treatment includes a standing and then freezing crosslinking step; standing allows the crosslinking agent to react chemically with the active groups on the polymer chain, providing a basic framework for further crosslinking; low-temperature freezing causes the polymer chain segments to aggregate tightly and promotes the uniform distribution of chemical crosslinking points, forming a dense and stable double network structure after thawing, which significantly improves the mechanical strength, structural stability and deformation resistance of the double network gel electrolyte.

[0030] In this invention, the freeze-crosslinking step includes freezing followed by thawing; Optionally, the freezing temperature is -25 to -20°C, and the freezing time is 8-12 hours; Optionally, the thawing temperature is room temperature (20-25℃) and the time is 5-10 hours.

[0031] In one optional embodiment, the gelation treatment includes a step of inducing crosslinking with multivalent metal ions after standing; standing allows the crosslinking agent to react chemically with the active groups on the polymer chain, providing a basic framework for further crosslinking; by utilizing the multivalent metal ions to form coordination bonds with functional groups such as carboxyl and hydroxyl groups on the polymer chain, a secondary crosslinking network is constructed on the basis of the original chemical crosslinking, further improving the network density and interface stability, which can better suppress zinc dendrite growth and extend the battery cycle life.

[0032] In this invention, when polyvalent metal ions induce crosslinking, the polyvalent metal ions are generally prepared into a solution for use. The specific concentration can be adjusted according to the actual crosslinking situation. Typically, without limitation, when zinc ions and manganese ions are included, the concentration of zinc ions is 0.1-0.5 mol / L and the concentration of manganese ions is 0.1-0.5 mol / L. The product after standing is completely immersed in the polyvalent metal ion solution for 1-5 hours.

[0033] A third aspect of this invention protects a secondary battery, wherein the secondary battery comprises the aforementioned dual-network gel electrolyte or the dual-network gel electrolyte prepared by the aforementioned preparation method.

[0034] The technical solution of this invention has the following advantages: 1. This invention provides a dual-network gel electrolyte, wherein the raw materials of the dual-network gel electrolyte include a first polymer, a second polymer, a metal salt, a plasticizer, a crosslinking agent, and a solvent; the first polymer forms a flexible first network through chemical crosslinking, serving as the main channel for ion transport to ensure high ionic conductivity; simultaneously, the second polymer is introduced, interpenetrating with the first network through physical or chemical action to form a second network as a "sacrificial bond"; through synergistic effect, when subjected to external forces (such as zinc dendrite growth stress), the second network preferentially undergoes reversible destruction to dissipate energy, thereby protecting the integrity of the main chain structure and ion channels of the first network, ultimately enabling the gel to obtain excellent mechanical properties such as high toughness and puncture resistance while maintaining high ionic conductivity and excellent capacity retention, solving the problem of mutual constraint between the two in traditional solutions; 2. This invention provides a method for preparing a dual-network gel electrolyte, wherein the preparation method includes the following steps: S1, mixing a first polymer, a second polymer, a metal salt, a plasticizer, and a solvent to obtain a precursor solution; S2, mixing the precursor solution and a crosslinking agent, and performing a gelation treatment to obtain a dual-network gel electrolyte; This invention first mixes the first polymer, the second polymer, the metal salt, the plasticizer, and the solvent; then, gelation is initiated by a crosslinking agent, so that the first polymer forms a flexible main network as an ion transport channel, and the second polymer is entangled and interwoven with the main network to form a high-strength auxiliary network, ultimately achieving a synergistic improvement in mechanical strength and capacity retention of the dual-network gel electrolyte; Meanwhile, the present invention has a simple process, controllable conditions, and readily available raw materials, and can stably prepare a dual-network gel electrolyte that takes into account both mechanical and electrochemical properties. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a graph showing the electrical test data of the full cell assembled with a dual-network gel electrolyte in Example 1 at a 1C rate; Figure 2 This is a graph showing the electrical test data of the full cell assembled with a dual-network gel electrolyte in Example 2 at a 1C rate; Figure 3 This is a graph showing the electrical test data of the full cell assembled with the dual-network gel electrolyte in Example 3 at 1C rate; Figure 4 The graph shows the electrical test data of the full cell assembled with gel electrolyte in Comparative Example 1 at a 1C rate. Figure 5 The graph shows the electrical test data of the full cell assembled with gel electrolyte in Comparative Example 2 at a 1C rate. Detailed Implementation

[0037] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0038] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0039] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0040] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This range can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this invention, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein; "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] In the description of the embodiments of the present invention, the term "and / or" is merely a description of the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0042] In the description of the embodiments of the present invention, the term "at least one" refers to one or more (including two).

[0043] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0044] The gelatin was purchased from Aladdin, specifically MDL brand number MFCD00081638; The weight-average molecular weight of polyvinyl alcohol is 10,000~200,000 g / mol. It was purchased from Aladdin, and the specific MDL brand name is MFCD00081922. The sodium alginate was purchased from Aladdin, specifically brand name MFCD00081310; The carboxylated cellulose nanofibers were purchased from Xianfeng Nano, with an average diameter of 6.0 nm and an average length of 2.5 μm.

[0045] Example 1 This embodiment provides a dual-network gel electrolyte, the preparation method of which includes the following steps: S1, weigh 1.0 g of gelatin and disperse it in 6.0 g of deionized water. After swelling at 25°C for 1 h, place it in a 50°C water bath and stir for 6 h to obtain solution A; weigh 0.8 g of polyvinyl alcohol and disperse it in 6.0 g of deionized water. Stir at 95°C for 6 h and cool to 50°C to obtain solution B; mix solution A and solution B, add 3.0 g of zinc trifluoromethanesulfonate and 2.0 g of glycerol, and stir at 50°C for 4 h to obtain the precursor solution; S2, the precursor solution and 0.03g genipin were mixed and stirred rapidly for 2 minutes, then injected into a polytetrafluoroethylene mold. The mold was placed in a 25°C environment and left to stand for 6 hours to crosslink and obtain a nascent gel. The nascent gel was placed in a -20°C freeze for 12 hours, then transferred to a 25°C thaw for 6 hours to further crosslink and obtain a double-network gel electrolyte.

[0046] Example 2 This embodiment provides a dual-network gel electrolyte, the preparation method of which includes the following steps: S1, weigh 1.2g of gelatin and disperse it in 7.0g of deionized water, swell at 25°C for 1h, then stir in a 50°C water bath for 6h to obtain solution A; weigh 0.5g of sodium alginate and disperse it in 7.0g of deionized water, stir for 6h to obtain solution B; mix solution A and solution B, add 2.0g of zinc sulfate and 1.5g of ethylene glycol, stir at 50°C for 1h to obtain the precursor solution; S2, the precursor solution and 0.02g genipin were mixed and stirred rapidly for 2 minutes, then injected into a polytetrafluoroethylene mold. The mold was placed in a 25°C environment and left to stand for 4 hours to crosslink and obtain a nascent gel. Zinc sulfate, manganese sulfate and water were mixed to obtain a salt solution with a zinc ion concentration of 0.5mol / L and a manganese ion concentration of 0.1mol / L. The nascent gel was soaked in the salt solution for 2 hours to further crosslink and obtain a double-network gel electrolyte.

[0047] Example 3 This embodiment provides a dual-network gel electrolyte, the preparation method of which includes the following steps: S1, 1.0 g of gelatin was weighed and dispersed in 8.0 g of deionized water, swollen at 25°C for 1 h, and then stirred in a 50°C water bath for 6 h to obtain solution A; 0.3 g of carboxylated cellulose nanofibers were weighed and slowly added to solution A under ultrasonic treatment, and ultrasonicated for 30 min to obtain a suspension; 2.5 g of zinc acetate, 0.2 g of manganese acetate and 2.0 g of 1-ethyl-3-methylimidazolium acetate were added to the suspension, and stirred at 50°C for 3 h to obtain the precursor solution; S2, the precursor solution and 0.04g genipin were mixed and stirred rapidly for 2 minutes, then injected into a polytetrafluoroethylene mold and placed in a 25°C environment for 24 hours to obtain a double-network gel electrolyte.

[0048] Comparative Example 1 This comparative example provides a gel electrolyte, the preparation method of which includes the following steps: Weigh 1.5g of gelatin and disperse it in 8.5g of deionized water. After swelling at 25°C for 1 hour, place it in a 50°C water bath and stir for 6 hours. Add 3.0g of zinc trifluoromethanesulfonate and 2.0g of glycerin, and stir at 50°C for 4 hours. Add 0.03g of genipin and stir rapidly for 2 minutes. Then pour the mixture into a polytetrafluoroethylene mold and place the mold at 25°C for 12 hours to obtain a gel electrolyte.

[0049] Comparative Example 2 This comparative example provides a gel electrolyte, the preparation method of which includes the following steps: Weigh 1.5g of gelatin and disperse it in 10.0g of deionized water. After swelling at 25°C for 1h, place it in a 50°C water bath and stir for 6h. Add 3.0g of zinc trifluoromethanesulfonate and stir at 50°C for 4h. Stir rapidly for 2 minutes, then pour it into a polytetrafluoroethylene mold. Place the mold at 25°C and let it stand for 12h to obtain a gel electrolyte.

[0050] Comparative Example 3 This comparative example provides a gel electrolyte, the preparation method of which includes the following steps: S1, weigh 1.6g of polyvinyl alcohol and disperse it in 12.0g of deionized water, stir at 95°C for 6h, cool to 50°C to obtain a solution, add 3.0g of zinc trifluoromethanesulfonate and 2.0g of glycerol, stir at 50°C for 4h to obtain a precursor solution; S2, the precursor solution and 0.03g genipin were mixed and stirred rapidly for 2 minutes, then injected into a polytetrafluoroethylene mold. The mold was placed in a 25°C environment and left to stand for 6 hours to complete the first crosslinking and obtain the nascent gel. The nascent gel was placed in a -20°C freezer for 12 hours and then transferred to a 25°C thawer for 6 hours to complete the second crosslinking and obtain the gel electrolyte.

[0051] Test case Positive electrode preparation: α-MnO2 active material, acetylene black and polyvinylidene fluoride were mixed in a mass ratio of 7:2:1, and N-methylpyrrolidone was used as a solvent to prepare a slurry. The slurry was coated on a titanium foil current collector, dried under vacuum at 80°C for 12 hours, and then pressed into a sheet to obtain the MnO2 positive electrode. The dual-network gel electrolyte prepared in the examples and comparative examples was used as the electrolyte and separator, and the zinc foil was used as the negative electrode. The MnO2 positive electrode was assembled into a CR2032 coin cell in a glove box. Electrical performance testing was conducted using the Blue Electric testing system. Test method for charge and discharge capacity: Charge the battery at a rate of 1C to 1.85V, and obtain the 1C charge specific capacity according to the battery mass; then discharge the battery at a rate of 1C to 0.85V, and obtain the 1C discharge specific capacity according to the battery mass. Coulomb efficiency = (charge capacity / discharge capacity) × 100%; The test method for capacity retention is as follows: At 25°C, the battery is charged to 1.85V at a rate of 1C, and then discharged to 0.85V at a rate of 1C, and this cycle is repeated 150 times. The capacity retention rate on the 150th cycle is calculated as: (Discharge capacity on the 150th cycle / Discharge capacity on the 1st cycle) × 100%. Table 1. Test data on the electrical properties of the dual-network gel electrolyte

[0052] Tensile strength, compressive strength, and shear strength were tested using a universal testing machine. The test results are shown in Table 2; Table 2 Test data of mechanical properties of dual-network gel electrolyte

[0053] Combining Tables 1 and 2 and Figure 1-5 To conduct analysis, from Figure 1 It can be seen that the battery's discharge specific capacity remains stable at approximately 148.5 mAh·g after 500 cycles. -1 Near the same location, the coulombic efficiency remains close to 100%, and the capacity retention rate is still 88.4% at the 150th cycle. The dual-network gel electrolyte of this invention can effectively suppress zinc dendrite growth and maintain a stable ion transport channel, thereby giving the battery excellent cycle stability. from Figure 2 It can be seen that the battery's discharge specific capacity is approximately 176.0 mAh·g. -1 The capacity decays extremely slowly throughout the cycle, with a capacity retention rate of up to 96.0% after 150 cycles, while the coulombic efficiency remains at around 102.4%, which significantly enhances the adaptability of the dual-network gel electrolyte to electrode volume changes and extends the battery cycle life. from Figure 3 It can be seen that the battery's discharge specific capacity reaches 208.8 mAh·g. -1 The capacity retention was the highest among all embodiments, and the capacity retention was still 95.9% after 150 cycles, with the coulombic efficiency remaining stable at 100.3%. Although this embodiment only used static crosslinking (without freezing or ion post-treatment), it also achieved excellent electrochemical performance, demonstrating the universality of the dual-network structure design of the present invention. from Figure 4It can be seen that the battery capacity decays rapidly in the first few dozen cycles, and the capacity retention rate is only 68.7% at the 150th cycle, which is much lower than that of the embodiments. from Figure 5 It can be seen that the battery capacity decayed drastically in the early stages of cycling, with the capacity retention rate dropping to as low as 6.67% by the 150th cycle, and the coulombic efficiency fluctuating abnormally (111.3%). This is because the liquid electrolyte could not suppress the dendrite growth and side reactions of the zinc anode, leading to rapid battery failure and the inability of the battery to achieve long-term stable cycling.

[0054] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A dual-network gel electrolyte, characterized in that, The raw materials for the dual-network gel electrolyte include a first polymer, a second polymer, a metal salt, a plasticizer, a crosslinking agent, and a solvent.

2. The dual-network gel electrolyte according to claim 1, characterized in that, The mass ratio of the first polymer to the second polymer is 1:(0.1-1), and optionally 1:(0.4-0.8); And / or, the first polymer includes at least one of gelatin, agar, and hyaluronic acid; And / or, the second polymer includes at least one of polyvinyl alcohol, sodium alginate, polyacrylamide, cellulose nanofibers, chitosan, and polyacrylic acid.

3. The dual-network gel electrolyte according to claim 1 or 2, characterized in that, The mass ratio of the first polymer to the metal salt is 1:(0.1-5), and can be optionally 1:(1-3); And / or, the metal salt includes at least one of lithium salt, sodium salt, and zinc salt; optionally, it includes at least one of zinc trifluoromethanesulfonate, zinc sulfate, zinc acetate, zinc chloride, zinc nitrate, and zinc perchlorate.

4. The dual-network gel electrolyte according to any one of claims 1-3, characterized in that, The mass ratio of the first polymer to the plasticizer is 1:(0.5-3), and can be optionally 1:(1.25-3); And / or, the plasticizer includes at least one of glycerol, ethylene glycol, polyethylene glycol, and 1-ethyl-3-methylimidazolium acetate.

5. The dual-network gel electrolyte according to any one of claims 1-4, characterized in that, The crosslinking agent includes crosslinking agent A and optional crosslinking agent B; Optionally, the mass ratio of the first polymer to crosslinking agent A is 1:(0.01-0.05), or optionally 1:(0.02-0.04); Optionally, the crosslinking agent A includes at least one of genipin, glutaraldehyde, glyoxal, epichlorohydrin, and citric acid; Optionally, the crosslinking agent B comprises multivalent metal ions; optionally, it includes zinc ions and / or manganese ions.

6. The dual-network gel electrolyte according to any one of claims 1-5, characterized in that, The solvent includes at least one of water, ethanol, methanol, and acetone; Optionally, the mass ratio of the first polymer to the solvent is 1:(5-15).

7. A method for preparing a dual-network gel electrolyte according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: S1, mix the first polymer, the second polymer, the metal salt, the plasticizer, and the solvent to obtain the precursor solution; S2, the precursor solution and crosslinking agent are mixed and gelled to obtain a dual-network gel electrolyte.

8. The preparation method according to claim 7, characterized in that, In step S1, the first polymer and a portion of the solvent are mixed to obtain solution A; the second polymer and the remaining solvent are mixed to obtain solution B; solutions A and B are combined, and a metal salt and a plasticizer are added for a third mixing to obtain the precursor solution. Optionally, the temperature of the first mixing is 40-60°C, and the time is 5-8 hours; Optionally, the temperature of the second mixing is 80-98℃, and the time is 5-8 hours; Optionally, the temperature of the third mixing is 40-60°C, and the time is 1-5 hours.

9. The preparation method according to claim 7 or 8, characterized in that, The gelation process includes a settling step; Alternatively, the gelation treatment may include a step of freezing and crosslinking after standing; Alternatively, the gelation treatment may include a step of inducing crosslinking with multivalent metal ions after standing.

10. A secondary battery, characterized in that, The secondary battery includes the dual-network gel electrolyte as described in any one of claims 1-6 or the dual-network gel electrolyte prepared by the preparation method described in any one of claims 7-9.

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