A self-limiting wetting hydrogel electrolyte membrane and its application

Abstract

This invention provides a self-limiting wetting hydrogel electrolyte membrane and its applications. The electrolyte membrane satisfies at least one of the following conditions (1) and (2): (1) it comprises at least one electrolyte salt that can self-absorb water to reach a deliquescent state when exposed to humid air and at least one non-highly hydrophilic polymer; or (2) it comprises at least one compound that can self-absorb water to reach a deliquescent state when exposed to humid air, at least one electrolyte salt, and at least one non-highly hydrophilic polymer. A method for its preparation and its applications in aqueous batteries, hybrid solid-liquid batteries, and fuel cells are also provided. This invention not only enhances the mechanical strength of the electrolyte membrane but also achieves the goal of high ionic conductivity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of batteries, and relates to a self-limiting wet hydrogel electrolyte membrane and a water-based battery, a hybrid solid-liquid battery and a fuel cell using the electrolyte membrane. BACKGROUND

[0002] In recent years, with the rapid development of portable electronic devices and electric vehicles, people's requirements for power supply are increasing. Lithium ion batteries have the advantages of high energy density and have been widely used in small electronic devices and power supplies for electric vehicles. However, the electrolyte of lithium ion batteries is based on an organic solvent system, which still has disadvantages such as flammability and toxicity. In contrast, water-based batteries and fuel cells based on water-based electrolytes and hybrid solid-liquid batteries based on water / solid-state electrolytes have characteristics such as non-flammability and environmental friendliness, and therefore have received extensive research attention.

[0003] However, current water-based batteries, hybrid solid-liquid batteries and fuel cells often use perfluorosulfonic acid membranes such as Nafion as the water-based electrolyte interlayer, which is usually limited by the high cost and production constraints of perfluorosulfonic acid membranes. Therefore, the development of polymer material membrane systems that can replace perfluorosulfonic acid membranes such as Nafion for water-based batteries and hybrid solid-liquid batteries and fuel cells is crucial for the further development and application of these battery systems. Hydrogel electrolyte systems are prepared by immersing or absorbing water-based liquid electrolyte that dissolves electrolyte salt into a hydrogel membrane to be used as an electrolyte membrane, and are considered an important choice to replace perfluorosulfonic acid membranes as electrolytes for water-based batteries and hybrid solid-liquid batteries and fuel cells.

[0004] However, hydrogel electrolytes prepared from high-hydrophilic polymers often need to control the mass fraction ratio of water and polymer. For example, if the mass fraction of water in the hydrogel is too low, the ionic conductivity of the hydrogel electrolyte will be too low (<10 -4 S / cm), thus making the internal resistance of the assembled full cell too high and unable to discharge normally; and if the mass fraction of water in the hydrogel is too high, the mechanical strength of the hydrogel will rapidly deteriorate, and an independently supported electrolyte membrane cannot be prepared. Therefore, controlling the water content and / or the chemical composition and structure of the polymer backbone in the hydrogel electrolyte to balance the ionic conductivity and mechanical strength of the hydrogel electrolyte is one of the main scientific and technical challenges in this technical field.

[0005] The main technical means in the current field is to add ceramic, glass or polymer fiber support additives in the hydrogel electrolyte polymer skeleton, or to use (in situ) solidification and other modes to strengthen its mechanical strength. On the other hand, the current hydrogel electrolyte is often synthesized by directly synthesizing a water-containing film or by immersing and absorbing a water-based electrolyte after preparing a dry film of the polymer. These processes can improve the ion conductivity and mechanical strength of the hydrogel electrolyte to some extent, but often involve complex chemical reaction steps and operations, which is not conducive to the further widespread application of hydrogel electrolytes in water-based batteries and hybrid solid-liquid batteries and fuel cells. SUMMARY

[0006] To at least solve one of the problems in the prior art, the present application provides a self-limiting wetting hydrogel electrolyte membrane to solve the ion conductivity and mechanical strength challenges of hydrogel electrolytes. The technical principle of the present application is to introduce a compound and / or electrolyte salt that can self-absorb water to reach a deliquescent state under room temperature and humid air conditions, and to use a blend structure of various compounds and / or salts and / or polymers with hydrophilic and hydrophobic properties, and to thereby adjust the amount of water spontaneously absorbed by the hydrogel electrolyte under actual application conditions, so as to spontaneously form a hydrogel electrolyte with high ion conductivity and moderate mechanical strength under battery use conditions.

[0007] A self-limiting wetting hydrogel electrolyte membrane at least meets one of the following conditions (1) and (2):

[0008] (1) comprising at least one electrolyte salt that can self-absorb water to reach a deliquescent state under exposure to humid air conditions, and at least one non-highly hydrophilic polymer;

[0009] (2) comprising at least one compound that can self-absorb water to reach a deliquescent state under exposure to humid air conditions, at least one electrolyte salt, and at least one non-highly hydrophilic polymer.

[0010] In some embodiments, the humid air refers to air with a relative humidity of between 30% and 300% at room temperature; optionally, the relative humidity is between 40% and 150%, or optionally, the relative humidity is selected from 50% to 120%.

[0011] In some embodiments, the electrolyte salt refers to a compound that can be ionized into anions and cations to play an ion conductive role after being dissolved in water, and can be a lithium salt (such as lithium chloride), a sodium salt, a potassium salt, an ammonium salt, a nitrate salt, a sulfate salt, and a perchlorate salt.

[0012] In some embodiments, the electrolyte salt capable of self-absorbing water to reach deliquescent state under exposure to humid air condition refers to a salt capable of self-dissolving on the surface within 2 hours of spontaneous water absorption at room temperature under air condition exposed to 30% relative humidity; and can be selected from lithium chloride, magnesium chloride, calcium chloride and other chlorides, lithium perchlorate and other perchlorates.

[0013] In some embodiments, the non-highly hydrophilic polymer refers to a polymer with a weight of 110%-300% of the weight before water absorption after spontaneous water absorption for 2 hours at room temperature under air condition exposed to 30% relative humidity; and can be selected from single polymer, copolymer, block polymer, graft polymer or mixture of polymers with hydrophilic groups (polyether, polyester, hydroxyl and / or carboxyl) and other polymers with the above characteristics.

[0014] In some examples, the non-highly hydrophilic polymer is selected from polyethylene-polyethylene glycol copolymer (PE-co-PEG) with a molecular weight of 2000-4000 and a molar ratio of polyethylene to polyethylene glycol of (2-3):(7-8).

[0015] In some specific examples, the non-highly hydrophilic polymer is selected from polyethylene-polyethylene glycol copolymer with a molecular weight of 4000 and a molar ratio of polyethylene to polyethylene glycol of 3:7.

[0016] In some specific examples, the non-highly hydrophilic polymer is selected from polyethylene-polyethylene glycol copolymer with a molecular weight of 2000 and a molar ratio of polyethylene to polyethylene glycol of 2:8.

[0017] In some specific examples, the non-highly hydrophilic polymer is selected from polyethylene-polyethylene glycol copolymer with a molecular weight of 40000 and a molar ratio of polyethylene to polyethylene glycol (PE:PEO) of (1-3):(7-9), such as 1:9.

[0018] In some examples, the complete drying generally refers to a water content of less than 1%; alternatively, the water content is less than 0.5%, and further alternatively, the water content is less than 0.2%.

[0019] In some examples, for condition (1) above, the mass ratio of the electrolyte salt capable of self-absorbing water to reach deliquescent state under exposure to humid air condition to the non-highly hydrophilic polymer is 20-40%, alternatively 25-35%, and further alternatively 30%. It is found that if the content of the electrolyte salt is low (e.g., ≤5%), the hydrogel electrolyte film cannot spontaneously wet to achieve a high ionic conduction state (ionic conductivity is less than 10 -6If the content of electrolyte salt is high (e.g., ≥ 100%), the hydrogel electrolyte film loses mechanical strength completely after spontaneous wetting and cannot maintain the shape of a self-supporting film.

[0020] In some embodiments, the self-limiting wetting hydrogel electrolyte film comprises a polyethylene-polyethylene glycol copolymer and an electrolyte salt; the molecular weight of the polyethylene-polyethylene glycol copolymer is 2000-4000, and the molar ratio of polyethylene to polyethylene glycol is (2-3):(7-8); the electrolyte salt is a chloride or a perchlorate, and lithium chloride is optionally used; the mass ratio of the electrolyte salt to the polyethylene-polyethylene glycol copolymer is 20-40%, optionally 25-35%, and further optionally 30%.

[0021] In some embodiments, the compound that can spontaneously absorb water to reach a deliquescent state under exposure to humid air conditions refers to an organic compound and a non-ionic oxide that can spontaneously undergo surface dissolution within 2 hours after being exposed to air conditions at 30% relative humidity at room temperature, and optionally a polyhydroxy aldehyde ketone, phosphorus pentoxide.

[0022] In some embodiments, the condition (1) described above further optionally comprises at least one highly hydrophobic polymer or / and at least one highly hydrophilic polymer or / and an additive component.

[0023] In some embodiments, the condition (2) described above further optionally comprises at least one or more additive components.

[0024] In some embodiments, the highly hydrophobic polymer refers to a polymer with a water contact angle greater than 90 degrees. For example, polytetrafluoroethylene, polyethylene, polypropylene.

[0025] The highly hydrophilic polymer refers to a polymer with a water contact angle less than 60 degrees and a characteristic of having a weight after water absorption that is more than 300% of the weight before water absorption after the completely dried polymer is exposed to air conditions at 30% relative humidity at room temperature and spontaneously absorbs water for 2 hours. For example, polyethylene glycol, polyamide, PET (polyethylene terephthalate).

[0026] The moderately hydrophobic polymer refers to a polymer with a water contact angle greater than or equal to 60 degrees and less than or equal to 90 degrees. For example, PVDF (polyvinylidene fluoride), modified PVDF, polyacrylate.

[0027] The additive component includes but is not limited to an additive with an electrochemical redox reaction, such as but not limited to iodides including but not limited to lithium iodide, sodium iodide, potassium iodide, metal complexes such as ferrocene, cobaltocene, organic redox substrates such as p-diphenol, and the like.

[0028] In addition to the necessary conditions (1) or (2), the above self-limiting wetting hydrogel electrolyte membrane can also optionally contain one or more of the following: an additive component A known in the field of electrochemical energy storage research, which has electrochemical redox activity in aqueous batteries and flow batteries and is used as a soluble electrode material, preferably selected from the group consisting of lithium iodide, sodium iodide, potassium iodide, and other iodides, ferrocene, cobaltocene and their derivatives, organic redox substrates such as p-diphenol and its derivatives, and the like; and / or an additive component B, which is one or more moderately hydrophobic polymers or / and a highly hydrophilic polymer, preferably selected from the group consisting of polyacrylamide and its derivatives.

[0029] The self-limiting wetting hydrogel electrolyte membrane of the present application has a total ionic conductivity of not less than 10 -4 S / cm.

[0030] The present application also provides a method for preparing the above self-limiting wetting hydrogel electrolyte membrane, which comprises: dissolving or uniformly dispersing all components of the self-limiting wetting hydrogel electrolyte membrane in an aqueous or organic solvent; forming a thin film; and drying.

[0031] The present application also provides the use of the above self-limiting wetting hydrogel electrolyte membrane as a self-supporting electrolyte membrane in a membrane electrode of an aqueous battery, a hybrid solid-liquid battery, or a fuel cell.

[0032] The present application also provides a battery comprising the above self-limiting wetting hydrogel electrolyte membrane.

[0033] The present application provides an aqueous battery using the above self-limiting wetting hydrogel electrolyte membrane in its electrolyte layer.

[0034] The present application provides a hybrid solid-liquid battery, wherein the electrolyte of the battery comprises a double or multi-layer stack of the above self-limiting wetting hydrogel electrolyte membrane and one or more common oxide electrolyte sheets.

[0035] The present application provides a fuel cell, wherein the membrane electrode of the fuel cell comprises the above self-limiting wetting hydrogel electrolyte membrane, and a catalyst layer and an air diffusion electrode layer are stacked on both ends of the self-limiting wetting hydrogel electrolyte membrane.

[0036] The present invention also provides a method for assembling the above-mentioned battery, satisfying one of the following conditions (1) and (2): (1) before assembling a closed battery, the self-restricted wetting hydrogel electrolyte membrane is exposed to humid air for self-restricted wetting and then placed into a closed battery for assembly; or (2) when assembling an open battery such as an air battery or fuel cell, after optionally using a composite method commonly used in the art to composite one or both ends of the dry film with the catalyst layer and / or the air diffusion electrode layer, it is directly placed into an open battery for assembly. Before these batteries are placed under humid air conditions for operation, they are left to stand for no more than 2 hours for a self-restricted wetting process.

[0037] Compared with the prior art, the present invention has at least the following beneficial effects:

[0038] This invention provides a self-limiting wetting hydrogel electrolyte suitable for aqueous batteries, hybrid solid-liquid batteries, and fuel cells. Its technical advantages are: (1) By adding a self-deliquescent salt or compound, this self-limiting wetting hydrogel electrolyte can directly absorb water molecules from the air, thereby allowing the use of a dry film of the self-limiting wetting hydrogel electrolyte for battery assembly. Compared with common methods in the field that require the direct preparation of a wet film of the hydrogel electrolyte, this enhances mechanical strength and processing performance; (2) To prevent excessive spontaneous water absorption by the hydrogel electrolyte, which would lead to a decrease in mechanical strength and damage to the integrity of the membrane structure, the spontaneous water absorption of the hydrogel electrolyte under different air humidity conditions is adjusted by balancing the ratio of the hydrophilic phase (salt, compound, additive and / or polymer) and the hydrophobic phase in the hydrogel electrolyte, thereby achieving the goal of balancing high ionic conductivity and mechanical strength. Attached Figure Description

[0039] Figure 1 A schematic diagram of a typical preparation process for the self-limiting wetting hydrogel electrolyte membrane of Example 1 of the present invention. Wherein, 101 is the self-limiting wetting hydrogel electrolyte membrane; 201 is polyethylene glycol copolymer; 202 is lithium chloride; 203 is acetone; and 204 is a glass bottle.

[0040] Figure 2 This relates the ionic conductivity and mechanical strength of hydrogel electrolytes to water content.

[0041] Figure 3 The relationship between water content and air exposure time for low-wetting, high-wetting, and self-limiting wetting hydrogel electrolyte membranes.

[0042] Figure 4 This is a schematic diagram of a typical solid-liquid hybrid battery configuration assembled using a self-limiting wetting hydrogel electrolyte membrane.

[0043] In some embodiments, the self-limiting wetting hydrogel electrolyte membrane is prepared by dissolving or uniformly dispersing all the above described salts, compounds, polymers and additives in water or organic solvent, followed by a film preparation method commonly used in the field, including but not limited to solution casting, flow casting, spin coating, extrusion, rolling, etc., followed by a drying method commonly used in the field to prepare a dry film under low humidity air (relative humidity no higher than 10%) or reduced pressure / vacuum conditions. The dry film is exposed to humid air for self-limiting wetting before being assembled into a closed cell, or is directly assembled into an open cell such as an air cell or a fuel cell, and is optionally combined with a catalyst layer and / or an air diffusion electrode layer at one end or both ends of the dry film by a composite method commonly used in the field. The self-limiting wetting process is completed within 2 hours before the cell is placed in humid air for operation.

[0044] Figure 5 The ion conductivity of the self-limiting wetting hydrogel electrolyte membrane of Example 1 of the present application.

[0045] Figure 6 The ion conductivity of the low wetting hydrogel electrolyte membrane of Comparative Example 3.

[0046] Figure 7 The button-type hybrid solid-liquid lithium-air battery based on the self-limiting wetting hydrogel electrolyte membrane of Example 7 of the present application and its cycle curve.

[0047] Figure 8 The ion conductivity change relationship of the self-limiting wetting hydrogel electrolyte membrane after transferring from dry air to humid air. DETAILED DESCRIPTION

[0048] The following examples are used to illustrate the present application, but are not intended to limit the scope of the present application. If a specific technique or condition is not specified in the examples, it is performed according to the technique or condition described in the literature in the field, or according to the product manual. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be purchased through a regular channel.

[0049] As shown in Figure 1 In some embodiments, the preparation method of the self-limiting wetting hydrogel electrolyte membrane includes the following specific processes: dissolving or uniformly dispersing all the above described salts, compounds, polymers and additives in water or organic solvent, followed by a film preparation method commonly used in the field, including but not limited to solution casting, flow casting, spin coating, extrusion, rolling, etc., followed by a drying method commonly used in the field to prepare a dry film under low humidity air (relative humidity no higher than 10%) or reduced pressure / vacuum conditions. The dry film is exposed to humid air for self-limiting wetting before being assembled into a closed cell, or is directly assembled into an open cell such as an air cell or a fuel cell, and is optionally combined with a catalyst layer and / or an air diffusion electrode layer at one end or both ends of the dry film by a composite method commonly used in the field. The self-limiting wetting process is completed within 2 hours before the cell is placed in humid air for operation.

[0050] When the self-limiting wetting hydrogel electrolyte membrane is placed in air with a certain humidity, the water content of the material will continuously increase with the extension of the placement time, the ion conductivity of the membrane will also increase with the increase of the water content, and the mechanical properties of the membrane will decrease with the increase of the water content, and the results are shown in Figure 2as shown.

[0051] High wetting is a high proportion of highly hydrophilic polymer and self- absorbing water deliquescent electrolyte salt, self-limiting wetting of Example 1 and Example 2, low wetting of Comparative Example 3 results as shown in Figure 3

[0052] The typical solid-liquid hybrid battery configuration using self-limiting wetting hydrogel electrolyte membrane is shown in Figure 4 .

[0053] Example 1

[0054] Take 2g of polyethylene polyethylene glycol copolymer (PE-co-PEG, molecular weight 4000, PE:PEG=3:7), dissolved in 100mL of acetone, then add 0.6g of lithium chloride (LiCl) to the solution, i.e. the salt accounts for 30% of the polymer mass ratio, after dissolution in a polytetrafluoroethylene (PTFE) mold, then put it in a 40 degree Celsius and less than 10% relative humidity oven environment for drying, then take out the transparent hydrogel membrane from the mold. This hydrogel membrane spontaneously absorbs water at room temperature and 40% relative humidity, and exhibits high ion conductivity of more than 10 -3 S / cm at room temperature, the results are shown in Figure 5 .

[0055] Comparative Example 1

[0056] Similar to Example 1, take 2g of polyethylene polyethylene glycol copolymer (PE-co-PEG, molecular weight 4000, PE:PEG=3:7), dissolved in 100mL of acetone, then add 0.1g of lithium chloride (LiCl) to the solution, i.e. the salt accounts for 5% of the polymer mass ratio, after dissolution in a polytetrafluoroethylene (PTFE) mold, then put it in a 40 degree Celsius and less than 10% relative humidity oven environment for drying, then take out the transparent hydrogel membrane from the mold. This hydrogel membrane cannot spontaneously wet in an environment with a relative humidity of less than 70% to achieve a high ion conductivity state (ion conductivity less than 10 -6 S / cm).

[0057] Comparative Example 2

[0058] ​Similar to Example 1, 2 g of polyethylene polyethylene glycol copolymer (PE-co-PEG, molecular weight 4000, PE:PEG = 3:7) was weighed and dissolved in 100 mL of acetone, and 2 g of lithium chloride (LiCl) was added to the solution, i.e., the salt was 100% of the polymer mass ratio, and after dissolution, it was cast in a polytetrafluoroethylene (PTFE) mold, and then placed in an oven environment at 40 degrees Celsius and a relative humidity of less than 10%, and then the hydrogel film was taken out of the mold, and a large amount of white insoluble particulate matter was observed in the dried film, and under a relative humidity of more than 40%, the hydrogel film spontaneously wetted and completely lost mechanical strength, and could not maintain the shape of a self-supporting film.

[0059] Example 2

[0060] 0.6 g of lithium chloride (LiCl) was weighed and dissolved in 100 mL of deionized water solution, and after heating to 60 degrees Celsius, 2 g of polyethylene polyethylene glycol copolymer (PE-co-PEG, molecular weight 4000, PE:PEG = 3:7) was added to the solution, i.e., the salt was 30% of the polymer mass ratio, and after dissolution, it was cast in a glass mold, and then dried at room temperature and in a blowing environment with a relative humidity of less than 10%, and then a transparent hydrogel film was taken out of the mold.

[0061] Example 3

[0062] Similar to Example 2, the difference is that after obtaining the polymer and salt solution, the solvent is volatilized to about 50% or so to form a viscous liquid, and then a casting method is used to coat it on a glass substrate using a doctor blade, and then dried at room temperature and in a blowing environment with a relative humidity of less than 10%, and then a transparent hydrogel film was taken off the glass substrate.

[0063] Example 4

[0064] 10 g of polyethylene polyethylene glycol copolymer (PE-co-PEG, molecular weight 2000, PE:PEG = 2:8) was weighed and placed in a glass beaker, and heated to 150 degrees Celsius to form a liquid, and 3 g of lithium chloride (LiCl) was added to the liquid and stirred to dissolve, and then cast in a polytetrafluoroethylene (PTFE) mold to obtain a thick film. The thick film was cut into pieces and added to a screw extrusion stage, and hot extruded at 110 degrees Celsius using a linear extrusion head with an extrusion shape of 5 cm wide and 100 microns thick square, thereby obtaining about 5 cm x 100 microns of hydrogel dry film. The obtained hydrogel dry film can be further calendered using a hot roller press to obtain a thinner electrolyte film.

[0065] Comparative Example 3

[0066] Similar to Example 1, 2g of polyethylene glycol copolymer (PE-co-PEG, molecular weight 4000, PE:PEG = 3:7) was weighed and dissolved in 100mL of acetone. Then, 0.4g of lithium chloride (NaCl) was added to the solution, resulting in a salt content of 20% of the polymer mass. After dissolution, the solution was poured into a polytetrafluoroethylene (PTFE) mold and dried in an oven at 40°C and a relative humidity of less than 10%. The transparent hydrogel film was then removed from the mold. Even in an environment with a relative humidity of 90%, this hydrogel film could not spontaneously wet to achieve a high ionic conductivity state (ionic conductivity less than 10). -8 S / cm), such as Figure 6 As shown.

[0067] Example 6

[0068] Weigh 2g of polyethylene glycol copolymer (PE-co-PEG, molecular weight 4000, PE:PEG = 3:7), dissolve it in 100mL of deionized water, then add 0.4g of lithium chloride (LiCl) and 0.2g of lithium iodide (LiI) to the solution, i.e., the salt accounts for 30% of the polymer mass. After dissolving, pour it into a polytetrafluoroethylene (PTFE) mold, and then dry it in an oven at 40 degrees Celsius and relative humidity less than 10%. After that, remove the yellow transparent hydrogel film from the mold.

[0069] Example 7

[0070] The lithium iodide-containing self-wetting hydrogel electrolyte membrane described in Example 6 was prepared according to... Figure 4 The method described is to assemble a coin cell hybrid solid-liquid battery. Specifically, carbon paper, a completely dry hydrogel electrolyte membrane, a lithium lanthanum zirconium oxide electrolyte sheet, and a lithium metal sheet are sequentially stacked under drying conditions and encapsulated in a perforated coin cell air battery casing. Then, charge-discharge tests are conducted under normal indoor conditions with humidity variations between 30% and 60%. The results are as follows... Figure 7 As shown. This hybrid solid-liquid air battery has a polarization of approximately 1V and can stably cycle for more than 30 times. This hybrid solid-liquid air battery exhibits activation characteristics under humid conditions. Figure 8 Therefore, it has the effect of suppressing self-discharge when assembled, stored and transported in low humidity environments.

[0071] Example 8

[0072] Example 1 2g of polyethylene-polyethylene glycol copolymer (PE-co-PEG, molecular weight 4000, PE:PEG = 3:7) was weighed and dissolved in 100 mL of deionized water. 0.4 g of lithium chloride (LiCl), 0.2 g of lithium hydroxide (LiOH), and 0.6 g of zinc chloride (ZnCl2) were added to the solution. After dissolution, the solution was cast in a polytetrafluoroethylene (PTFE) mold, and then placed in an oven at 40 °C and a relative humidity of less than 10% to dry. After drying, a transparent hydrogel membrane was removed from the mold. A manganese dioxide (MnO2) electrode sheet, a hydrogel electrolyte membrane in a completely dry state, and a zinc metal sheet were stacked in sequence under dry room conditions and packaged in a battery shell with a hole. The aqueous battery can be activated for normal discharge under standard indoor conditions; under dry packaging conditions, the ionic conductivity of the hydrogel electrolyte membrane is extremely low (less than 10 -6 S / cm) under non-moisture conditions, so the self-discharge process can be inhibited.

[0073] Example 9

[0074] 2g of polyethylene-polyethylene oxide copolymer (PE-co-PEO, molecular weight 40000, PE:PEO = 1:9) was weighed and dissolved in 100 mL of deionized water. 0.4 g of lithium chloride (LiCl) and 0.4 g of lithium hydroxide (LiOH) were added to the solution. After heating to evaporate the solvent to about 50%, a viscous liquid was obtained. The liquid was coated on a glass substrate using a casting method with a doctor blade. After drying at room temperature and a relative humidity of less than 10% in a blowing environment, a transparent hydrogel membrane was removed from the glass substrate. Carbon paper modified with carbon platinum catalyst was then stacked on both sides of the hydrogel to form a membrane electrode structure (MEA) for a fuel cell, which can be used for fuel cell assembly.

[0075] After comparing the examples with the comparative examples, it can be seen that the self-limiting wetting hydrogel electrolyte membrane described in the present application has both low humidity chemical stability and easy processing performance, as well as acceptable mechanical strength and high ionic conductivity performance under high humidity, thereby overcoming the disadvantages of low ionic conductivity of low-wetting hydrogel electrolyte and low mechanical strength and film integrity of high-wetting hydrogel electrolyte. Compared with the current general preparation process of directly preparing a hydrogel membrane for use as a self-supporting electrolyte membrane in an aqueous battery, a hybrid solid-liquid battery, and a fuel cell membrane electrode, the self-limiting wetting hydrogel electrolyte membrane of the present application has excellent processing performance under low humidity and dry conditions and can inhibit the self-discharge behavior, while the battery can be spontaneously activated under high humidity to achieve high-performance battery applications. Compared with commercial membranes such as Nafion and other perfluorosulfonic acid membranes that have similar moisture absorption properties under high humidity, the present application uses non-fluorine-containing polymers, which have the advantages of environmental friendliness and low cost.

[0076] While the application has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various modifications or changes can be made therein without departing from the spirit and scope thereof. Accordingly, it is intended that all such modifications and changes be included within the scope of the application as claimed.

Claims

1. A self-limiting wetting hydrogel electrolyte membrane, characterized by, at least one electrolyte salt which can self-absorb water to reach a deliquescent state under exposure to humid air conditions, and at least one non-highly hydrophilic polymer; the electrolyte salt which can self-absorb water to reach a deliquescent state under exposure to humid air conditions is selected from chloride or perchlorate, or is selected from lithium salt, sodium salt, potassium salt, ammonium salt, nitrate salt, sulfate salt; the non-highly hydrophilic polymer is selected from polyethylene polyethylene glycol copolymer with a molecular weight of 2000-4000 and a molar ratio of polyethylene to polyethylene glycol of (2-3):(7-8); or the non-highly hydrophilic polymer is selected from polyethylene polyoxyalkylene copolymer with a molecular weight of 40000 and a molar ratio of polyethylene to polyoxyalkylene of (1-3):(7-9); a mass ratio of the electrolyte salt which can self-absorb water to reach a deliquescent state under exposure to humid air conditions to the non-highly hydrophilic polymer is 25-35%.

2. The self-limiting wetting hydrogel electrolyte film of claim 1, wherein, a molar ratio of polyethylene to polyoxyalkylene in the polyethylene polyoxyalkylene copolymer is 1:

9.

3. The self-limiting wetting hydrogel electrolyte film of claim 1, wherein, a mass ratio of the electrolyte salt which can self-absorb water to reach a deliquescent state under exposure to humid air conditions to the non-highly hydrophilic polymer is 30%.

4. The self-limiting wetting hydrogel electrolyte film of claim 1, wherein, at least one highly hydrophobic polymer or / and at least one highly hydrophilic polymer or / and an additive component is further included.

5. The self-limiting wetting hydrogel electrolyte film according to any one of claims 1-4, wherein, The self-limiting wetting hydrogel electrolyte film has a total ionic conductivity no less than 10 -4 S / cm after spontaneously absorbing water for 2 hours under air conditions of no more than room temperature and no more than 50% relative humidity.

6. The method of claim any one of claims 1 to 5, wherein the self- limiting wetting hydrogel electrolyte film is prepared by, comprising: dissolving or uniformly dispersing all components of the self-limiting wetting hydrogel electrolyte membrane in an aqueous system or an organic solvent; making a thin film; drying.

7. Use of the self-limiting wetting hydrogel electrolyte membrane according to any one of claims 1-5 as a self-supporting electrolyte membrane in a membrane electrode of an aqueous battery, a hybrid solid-liquid battery or a fuel cell.

8. A battery, characterized by comprising the self-limiting wetting hydrogel electrolyte membrane according to any one of claims 1-5.

9. The battery of claim 8, wherein, the battery is an aqueous battery, and the self-limiting wetting hydrogel electrolyte membrane according to any one of claims 1-5 is used in an electrolyte layer of the battery.

10. The battery of claim 8, wherein, the battery is a hybrid solid-liquid battery, and the electrolyte of the hybrid solid-liquid battery comprises a double-layer or multi-layer stack of the self-limiting wetting hydrogel electrolyte membrane according to any one of claims 1-5 and one or more oxide electrolyte sheets.

11. The battery of claim 8, wherein, the battery is a fuel cell, and a membrane electrode of the fuel cell comprises the self-limiting wetting hydrogel electrolyte membrane according to any one of claims 1-5, and a catalyst layer and an air diffusion electrode layer are stacked on both ends of the self-limiting wetting hydrogel electrolyte membrane.

12. The method of assembling a battery of claim 8, wherein, one of the following conditions (1) and (2) is met, (1) before assembling a closed battery, the self-limiting wetting hydrogel electrolyte membrane is exposed to humid air for self-limiting wetting, and is placed in the closed battery for assembly; or (2) when assembling an open battery, one end or both ends of the dry self-limiting wetting hydrogel electrolyte membrane are combined with a catalyst layer and / or an air diffusion electrode layer, and then the self-limiting wetting hydrogel electrolyte membrane is directly placed in the open battery for assembly; before the battery is placed in a humid air condition for operation, the self-limiting wetting process is allowed to proceed for no more than 2 hours.

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