Gel electrolyte taking polyvinyl alcohol as main body material as well as preparation method and application of gel electrolyte

Abstract

The invention discloses a gel electrolyte taking polyvinyl alcohol as a main body material and a preparation method and application thereof, and the preparation method comprises the following steps: taking polyvinyl alcohol, zinc salt, amino acid and a water solvent as raw materials to synthesize a polyvinyl alcohol solution; preparing the polyvinyl alcohol solution into a film; and processing the prepared polyvinyl alcohol solution film by using liquid nitrogen rapid shaping and a one-time freeze thawing method to obtain the gel electrolyte taking polyvinyl alcohol as the main body material. The preparation method disclosed by the invention is safe and simple in process and low in cost, the gel electrolyte prepared by the preparation method has a stable structure, good mechanical strength and relatively good ion transmission efficiency, and a series of electrochemical properties of the aqueous zinc ion battery can be improved by applying the material to the aqueous zinc ion battery; and therefore, the cycle stability of the aqueous zinc ion battery is greatly improved, and the practical value is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a gel electrolyte with polyvinyl alcohol as a main material, and a preparation method and application thereof. Background Art

[0002] More and more countries and regions are turning their attention to new energy sources, such as electricity, wind power, and solar energy. Among them, stable and easily storable electricity is the most valued, which has led to the emergence of large-scale energy storage devices, national power grids, and other national heavy equipment. Portable mobile energy storage devices have also gradually become part of people's daily lives. With the successful commercial application of non-aqueous lithium-ion batteries, lithium-ion batteries have gradually occupied the vast majority of electricity usage environments. However, flammable and toxic organic electrolytes have always been a lingering cloud in the development of lithium-ion batteries, and the relatively scarce lithium metal in the earth's crust has also become a hidden danger in the development of lithium-ion batteries. Therefore, more and more battery systems have been fully researched and developed.

[0003] Among them, aqueous zinc-ion batteries have a high theoretical specific capacity (820 mAh g -1 ), abundant reserves of metallic zinc (more than 4 times that of lithium), low cost, non-toxicity, and low redox potential of the zinc metal negative electrode (-0.762V vs SHE), etc., and are considered to be a promising candidate battery for the development of large-scale grid energy storage systems.

[0004] The zinc anode is a key component in aqueous zinc-ion batteries, dominating their service life and coulombic efficiency. However, pure zinc as a zinc anode has problems such as easy formation of dendrites, hydrogen evolution reaction, and corrosion. Therefore, how to modify the zinc anode to inhibit dendrite growth, hydrogen evolution and corrosion reaction, and thus improve the cycle life and coulombic efficiency of aqueous zinc-ion batteries has become the focus of research on aqueous zinc-ion batteries. Currently, the modification of zinc anodes mainly focuses on the construction of artificial protective layers and the addition of trace additives. The construction of artificial protective layers requires that they are sufficiently dense, have good affinity with zinc metal, and have certain mechanical strength. The mechanical properties and density of the existing gel electrolyte protective layer based on polyvinyl alcohol need to be improved. Therefore, it is crucial to find a polyvinyl alcohol gel electrolyte with higher mechanical properties and density. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a gel electrolyte with polyvinyl alcohol as a main material and a preparation method and use thereof.

[0006] According to a first aspect of the present invention, a method for preparing a gel electrolyte with polyvinyl alcohol as a main material is provided, comprising: synthesizing a polyvinyl alcohol solution using polyvinyl alcohol, a zinc salt, an amino acid, and an aqueous solvent as raw materials; forming the polyvinyl alcohol solution into a film; and rapidly shaping the prepared polyvinyl alcohol solution film using liquid nitrogen and a single freeze-thaw method to obtain the gel electrolyte with polyvinyl alcohol as the main material.

[0007] In some exemplary embodiments, the step of synthesizing the polyvinyl alcohol solution further includes: dissolving an amino acid and a zinc salt in an aqueous solvent and stirring and mixing them uniformly to form a first solution; and dissolving polyvinyl alcohol in the first solution and stirring to obtain the polyvinyl alcohol solution.

[0008] In some exemplary embodiments, the zinc salt is zinc trifluoromethanesulfonate, zinc chloride, or zinc perchlorate, and the amino acid is glycine, threonine, or serine.

[0009] In some exemplary embodiments, the molar ratio of the zinc salt to the amino acid is 1:1-1:4.

[0010] In some exemplary embodiments, the stirring temperature during the stirring is 85-95° C., the stirring time is 6-8 hours, and both the first solution and the polyvinyl alcohol solution are homogeneous and transparent solutions.

[0011] In some exemplary embodiments, the step of preparing the polyvinyl alcohol solution into a film further comprises: using a syringe to extrude an appropriate amount of the polyvinyl alcohol solution, and using a four-sided preparation device to evenly apply the solution on a clean zinc foil to form a film.

[0012] In some exemplary embodiments, the appropriate amount of the polyvinyl alcohol solution is 2-3 ml, and the four-sided preparation device adopts a 100 μm specification.

[0013] In some exemplary embodiments, the step of using liquid nitrogen for rapid shaping and a single freeze-thaw method to prepare a polyvinyl alcohol solution membrane further includes: placing the prepared polyvinyl alcohol solution membrane into liquid nitrogen for cooling and shaping; placing the cooled and shaped polyvinyl alcohol solution membrane into a refrigerator for low-temperature insulation and standing treatment; and melting and drying the low-temperature insulation and standing polyvinyl alcohol solution membrane to obtain the gel electrolyte with polyvinyl alcohol as the main material.

[0014] In some exemplary embodiments, the cooling and setting temperature of the cooling and setting in liquid nitrogen is -196°C, and the cooling and setting time is 5-10 minutes. The low-temperature insulation temperature in the low-temperature insulation and static treatment is -20°C, and the low-temperature insulation time is 10-12 hours. The melting and drying temperature in the melting and drying is 20-30°C, and the melting and drying time is 36-48 hours.

[0015] According to a second aspect of the present invention, a gel electrolyte with polyvinyl alcohol as a main material is provided. The gel electrolyte with polyvinyl alcohol as a main material is prepared by the above-mentioned method for preparing a gel electrolyte with polyvinyl alcohol as a main material.

[0016] According to a third aspect of the present invention, an aqueous zinc ion battery is provided, which is coated with a gel electrolyte with polyvinyl alcohol as a main material, and the gel electrolyte with polyvinyl alcohol as a main material is prepared by the above-mentioned method for preparing a gel electrolyte with polyvinyl alcohol as a main material.

[0017] According to a fourth aspect of the present invention, there is provided a use of a gel electrolyte with polyvinyl alcohol as a main material, wherein the gel electrolyte with polyvinyl alcohol as a main material is prepared by the above-mentioned method for preparing a gel electrolyte with polyvinyl alcohol as a main material, and the gel electrolyte with polyvinyl alcohol as a main material is used in an aqueous zinc ion battery.

[0018] In some exemplary embodiments, the gel electrolyte with polyvinyl alcohol as the main material is used as the negative electrode gel electrolyte protective layer material of the aqueous zinc ion battery.

[0019] The present invention, compared with the prior art, has excellent results in that: polyvinyl alcohol is used as the matrix material, glycine, threonine, and serine are used as amino acid additives, and zinc trifluoromethanesulfonate, zinc chloride, and zinc perchlorate are used as zinc salts; the materials used are environmentally friendly; and the preparation process only requires three steps: water bath heating, liquid nitrogen cooling, and room temperature melting, resulting in a simple and low-cost preparation process. Furthermore, the novel gel electrolyte prepared using polyvinyl alcohol as the main material has a unique bonding method between its components, which can effectively increase its mechanical strength and density, inhibit the formation and growth of dendrites, and thus greatly improve the cycle stability of aqueous zinc ion batteries. At the same time, due to the presence of various electronegative groups, the material has greatly improved ionic conductivity and is superior to most current gel electrolyte materials for aqueous zinc ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a description of the drawings used in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be derived from these drawings without inventive effort.

[0021] Figure 1 The flowchart of the preparation method of the gel electrolyte with polyvinyl alcohol as the main material of the present invention is shown.

[0022] Figure 2 The present invention discloses a Fourier transform infrared spectrum of a gel electrolyte with polyvinyl alcohol as a main material.

[0023] Figure 3 This is a physical picture of the gel electrolyte of the present invention with polyvinyl alcohol as the main material.

[0024] Figure 4 This is a diagram showing the mechanical properties of the gel electrolyte using polyvinyl alcohol as the main material of the present invention.

[0025] Figure 5 This is a contact angle test diagram of the gel electrolyte with polyvinyl alcohol as the main material of the present invention.

[0026] Figure 6 This is a digital photo of a zinc ion battery pole piece prepared with a gel electrolyte using polyvinyl alcohol as a main material according to the present invention.

[0027] Figure 7 This is a scanning electron microscope surface image of a zinc ion battery electrode prepared using a gel electrolyte with polyvinyl alcohol as the main material.

[0028] Figure 8 This is a scanning electron microscope cross-sectional view of a zinc ion battery electrode prepared using a gel electrolyte with polyvinyl alcohol as the main material according to the present invention.

[0029] Figure 9 This is a cycle performance diagram of a zinc ion battery prepared with a gel electrolyte using polyvinyl alcohol as a main material according to the present invention.

[0030] Figure 10 This is a coulombic efficiency diagram of a zinc ion battery prepared with a gel electrolyte using polyvinyl alcohol as a main material according to the present invention. DETAILED DESCRIPTION

[0031] The essence of the technical solution of the present invention is explained in detail below.

[0032] The present invention uses polyvinyl alcohol, zinc salt, amino acid and water solvent as raw materials to synthesize a polyvinyl alcohol solution; prepares the polyvinyl alcohol solution into a film; and uses liquid nitrogen to quickly set the prepared polyvinyl alcohol solution film and a single freeze-thaw method to obtain a gel electrolyte with polyvinyl alcohol as the main material.

[0033] The technical solutions of the present invention are described below with reference to specific examples. However, the conditions and results described in the examples do not limit the scope of protection of this application. In addition, the experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0034] Figure 1The flow chart of the preparation method of the gel electrolyte with polyvinyl alcohol as the main material of the present invention is shown. Figure 1 As shown, the preparation method of the gel electrolyte with polyvinyl alcohol as the main material of the present invention includes the following steps.

[0035] In step 101, amino acid and zinc salt are dissolved in an aqueous solvent, and stirred and mixed to form a solution A.

[0036] In the embodiments of the present application, the zinc salt is zinc trifluoromethanesulfonate, zinc chloride or zinc perchlorate, and the amino acid is glycine, threonine or serine.

[0037] In the examples of the present application, the molar ratio of the zinc salt content to the amino acid content is 1:1-1:4.

[0038] In step 102 , polyvinyl alcohol is dissolved in solution A and stirred to obtain polyvinyl alcohol solution B.

[0039] In the embodiment of the present application, the stirring temperature in the stirring treatment of step 101 and step 102 is 85-95° C., and the stirring time is 6-8 h. In addition, both solution A and polyvinyl alcohol solution B are uniform and transparent solutions.

[0040] In step 103, the polyvinyl alcohol solution B is prepared into a film.

[0041] In the present embodiment, a suitable amount of polyvinyl alcohol solution B was squeezed out using a syringe and evenly coated on a clean zinc foil using a four-sided preparation device to form a film. In addition, the suitable amount of polyvinyl alcohol solution was 2-3 ml, and the four-sided preparation device used a 100 μm specification.

[0042] In step 104, the prepared polyvinyl alcohol solution film is placed in liquid nitrogen to be cooled and shaped.

[0043] In the embodiment of the present application, the obtained zinc foil with polyvinyl alcohol solution is placed in liquid nitrogen for cooling and shaping. The cooling temperature of the cooling and shaping treatment in liquid nitrogen is -196°C, and the cooling and shaping time is 5-10 minutes, preferably 10 minutes.

[0044] In step 105, the cooled and shaped polyvinyl alcohol solution film is placed in a refrigerator for low-temperature heat preservation and static treatment.

[0045] In an embodiment of the present application, the zinc foil with the polyvinyl alcohol solution film is placed in a refrigerator for low-temperature insulation and static treatment. The low-temperature insulation temperature in the low-temperature insulation and static treatment is -20°C, and the low-temperature insulation time is 10-12 hours, preferably 12 hours.

[0046] In step 106, the polyvinyl alcohol solution film after being kept at low temperature is melted and dried to obtain a gel electrolyte with polyvinyl alcohol as the main material.

[0047] In the embodiment of the present application, the zinc foil with polyvinyl alcohol solution film after low-temperature insulation is melted and dried at room temperature. The melting and drying time in the melting and drying process is 36-48h, preferably 36h, and the melting and drying temperature is 20-30℃, preferably 30℃.

[0048] Regarding the product prepared by the above method steps, the inventors conducted the following verification and characterization.

[0049] Figure 2 The present invention discloses a Fourier transform infrared spectrum of a gel electrolyte with polyvinyl alcohol as a main material. Figure 3 This is a physical picture of the gel electrolyte of the present invention with polyvinyl alcohol as the main material. Figure 4 This is a diagram showing the mechanical properties of the gel electrolyte using polyvinyl alcohol as the main material of the present invention. Figure 5 This is a contact angle test diagram of the gel electrolyte with polyvinyl alcohol as the main material of the present invention. Figure 6 This is a digital photo of a zinc ion battery pole piece prepared with a gel electrolyte using polyvinyl alcohol as a main material according to the present invention. Figure 7 This is a scanning electron microscope surface image of a zinc ion battery electrode prepared using a gel electrolyte with polyvinyl alcohol as the main material.

[0050] Figure 8 This is a scanning electron microscope cross-sectional view of a zinc ion battery electrode prepared using a gel electrolyte with polyvinyl alcohol as the main material according to the present invention.

[0051] like Figure 2 As shown in FIG, the product of the above preparation method was identified as a new type of gel electrolyte with polyvinyl alcohol as the main material by Fourier infrared spectrometer. Figure 3 As shown, it is dense and translucent gel. Figure 4 As shown in Figure 2, the stress-strain curve of the gel electrolyte with polyvinyl alcohol as the main material shows its good mechanical strength. Figure 5 As shown in FIG, the contact angle test shows that the contact angle of the gel electrolyte film with polyvinyl alcohol as the main material to the aqueous solution of zinc trifluoromethanesulfonate is 67.1°, proving that the obtained polyvinyl alcohol gel electrolyte film is a hydrophilic film, which is conducive to the rapid transfer of zinc ions. Figure 6 As shown in the figure, the digital camera photo of the gel electrolyte with polyvinyl alcohol as the main material proves its uniformity and tightness. Figure 7 、 8 As shown, the scanning electron microscope image shows that the gel electrolyte film with polyvinyl alcohol as the main material is about 100 μm thick and has a smooth and dense surface.

[0052] According to this embodiment, compared with the prior art, the excellent effect is that: polyvinyl alcohol is used as the base material, glycine, threonine, and serine are used as amino acid additives, zinc trifluoromethanesulfonate, zinc chloride, and zinc perchlorate are used as zinc salts, and the materials used are environmentally friendly; at the same time, the preparation process only requires three steps: water bath heating, liquid nitrogen cooling, and room temperature melting, and the preparation process is simple and low-cost.

[0053] The examples of the present application also describe a gel electrolyte with polyvinyl alcohol as the main material, which is prepared by the above-mentioned method for preparing a gel electrolyte with polyvinyl alcohol as the main material.

[0054] According to this embodiment, the gel electrolyte based on polyvinyl alcohol, prepared by the above-described preparation method, has a unique bonding pattern between its components, which effectively increases its mechanical strength and density, inhibits dendrite formation and growth, and significantly improves the cyclic stability of aqueous zinc-ion batteries. Furthermore, due to the presence of various electronegative groups, the ionic conductivity of this material is greatly improved, surpassing that of most current gel electrolyte materials for aqueous zinc-ion batteries.

[0055] The embodiments of the present application also describe a use of the above-mentioned gel electrolyte with polyvinyl alcohol as the main material. The gel electrolyte with polyvinyl alcohol as the main material is prepared by the above-mentioned method for preparing a gel electrolyte with polyvinyl alcohol as the main material. The gel electrolyte with polyvinyl alcohol as the main material is used in an aqueous zinc ion battery.

[0056] In an embodiment of the present application, the gel electrolyte with polyvinyl alcohol as the main material is used as a negative electrode protection material for an aqueous zinc ion battery.

[0057] According to this embodiment, since the gel electrolyte with polyvinyl alcohol as the main material prepared by the above preparation method has good mechanical properties and good ionic conductivity, applying this material to the negative electrode protective layer of the aqueous zinc ion battery can inhibit the formation and growth of dendrites and promote the desolvation process of zinc ions, thereby effectively improving a series of electrochemical properties of the aqueous zinc ion battery, thereby greatly improving the cycle life and coulombic efficiency of the aqueous zinc ion battery.

[0058] Figure 9 This is a cycle life diagram of an aqueous zinc ion battery using a gel electrolyte prepared by the above method with polyvinyl alcohol as the main material. It can be seen that at 1 mA·cm -2 The current density is 0.5 mAh cm -2At a capacity density of 1.5 GHz, the aqueous zinc-ion symmetrical battery coated with a gel electrolyte protective layer with polyvinyl alcohol as the main material can undergo a stable cycle of more than 1600 hours, which is 100% higher than the cycle life of the aqueous zinc-ion battery composed of pure zinc foil, indicating that it has an excellent cycle life. Figure 10 This is the coulombic efficiency diagram of an aqueous zinc ion battery using a gel electrolyte with polyvinyl alcohol as the main material prepared by the above method. It can be seen that at 3 mA cm -2 Current density, 1 mAh cm -2 At a capacity density of 1.5 GHz, an aqueous zinc-ion copper-zinc semi-symmetrical battery coated with a gel electrolyte protective layer made primarily of polyvinyl alcohol (PVA) can achieve a coulombic efficiency of nearly 100% for 240 cycles, a 100% improvement over the stable coulombic efficiency of 120 cycles for a pure copper-zinc semi-symmetrical battery. This demonstrates the excellent electrochemical performance of this gel electrolyte made primarily of PVA.

[0059] It should be understood that “one embodiment” or “an embodiment” mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, “in one embodiment” or “in an embodiment” appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are for description only and do not represent the advantages and disadvantages of the embodiments.

[0060] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0061] The above is merely an embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for preparing a gel electrolyte with polyvinyl alcohol as the main material, characterized in that: include: Using polyvinyl alcohol, zinc salt, amino acid and water solvent as raw materials, polyvinyl alcohol solution is synthesized; preparing the polyvinyl alcohol solution into a film; as well as The polyvinyl alcohol solution film prepared by rapid shaping with liquid nitrogen and a one-time freeze-thaw method is processed to obtain the gel electrolyte with polyvinyl alcohol as the main material.

2. The preparation method according to claim 1, characterized in that The step of synthesizing the polyvinyl alcohol solution further comprises: dissolving the amino acid and the zinc salt in an aqueous solvent, and stirring and mixing them to form a first solution; and Polyvinyl alcohol is dissolved in the first solution and stirred to obtain the polyvinyl alcohol solution.

3. The preparation method according to claim 2, characterized in that The zinc salt is zinc trifluoromethanesulfonate, zinc chloride or zinc perchlorate, The amino acid is glycine, threonine or serine.

4. The preparation method according to claim 2, characterized in that The molar ratio of the zinc salt content to the amino acid content is 1:1-1:

4.

5. The preparation method according to claim 2, characterized in that The stirring temperature during the stirring is 85-95°C and the stirring time is 6-8h. The first solution and the polyvinyl alcohol solution are both uniform and transparent solutions.

6. The preparation method according to claim 1, characterized in that The step of preparing the polyvinyl alcohol solution into a film further comprises: A proper amount of the polyvinyl alcohol solution was squeezed out using a syringe, and the solution was evenly coated on a clean zinc foil using a four-sided preparation device to form a film.

7. The preparation method according to claim 6, characterized in that The appropriate amount of the polyvinyl alcohol solution is 2-3 ml, and the four-sided preparation device adopts a 100 μm specification.

8. The preparation method according to claim 1, characterized in that The steps of using liquid nitrogen for rapid shaping and a single freeze-thaw method to prepare a polyvinyl alcohol solution film further include: The prepared polyvinyl alcohol solution film is placed in liquid nitrogen to cool and set; placing the cooled and shaped polyvinyl alcohol solution film in a refrigerator for low-temperature heat preservation and static treatment; and The polyvinyl alcohol solution film after being kept still at low temperature is melted and dried to obtain the gel electrolyte with polyvinyl alcohol as the main material.

9. The preparation method according to claim 8, characterized in that The cooling and setting temperature of the liquid nitrogen cooling and setting is -196°C, and the cooling and setting time is 5-10 minutes. The low-temperature insulation temperature in the low-temperature insulation static treatment is -20°C, and the low-temperature insulation time is 10-12 hours. The melting and drying temperature in the melting and drying is 20-30° C., and the melting and drying time is 36-48 hours.

10. A gel electrolyte with polyvinyl alcohol as the main material, characterized in that: The gel electrolyte with polyvinyl alcohol as the main material is prepared by the preparation method of the gel electrolyte with polyvinyl alcohol as the main material according to any one of claims 1 to 9.

11. An aqueous zinc ion battery, characterized in that: A gel electrolyte coated with polyvinyl alcohol as a main material is prepared by the method for preparing a gel electrolyte with polyvinyl alcohol as a main material according to any one of claims 1 to 9.

12. A use of a gel electrolyte with polyvinyl alcohol as the main material, characterized in that: The gel electrolyte with polyvinyl alcohol as the main material is prepared by the preparation method of the gel electrolyte with polyvinyl alcohol as the main material according to any one of claims 1 to 9, and the gel electrolyte with polyvinyl alcohol as the main material is used in an aqueous zinc ion battery.

13. The use of the gel electrolyte with polyvinyl alcohol as the main material according to claim 12, characterized in that: The gel electrolyte with polyvinyl alcohol as the main material is used as the negative electrode gel electrolyte protective layer material of the aqueous zinc ion battery.

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