A low-temperature solid electrolyte and its preparation method and application

Abstract

The present invention discloses a low-temperature solid electrolyte and a preparation method and application thereof, and belongs to the technical field of zinc-air batteries and their preparation. The present invention solves the problem that the existing solid electrolyte freezes under low temperature conditions, resulting in decreased conductivity and increased internal resistance. The present invention simply and quickly constructs a solid electrolyte material having both high ionic conductivity and low temperature resistance by introducing zinc salts and zwitterions into a polymer. The material is used in zinc-air batteries, and can circulate for more than 270 hours at a low temperature of 40°C. The charge and discharge voltage of the battery remains unchanged, and has good electrochemical stability. At the same time, it has the characteristics of high safety and low pollution, simple operation method, low cost, and universality. It is a new type of quasi-solid electrolyte that can be applied to the needs of industrial production of zinc-air batteries.

Description

Technical Field

[0001] The invention relates to a low-temperature solid electrolyte and a preparation method and application thereof, belonging to the technical field of zinc-air batteries and preparation thereof. Background Art

[0002] With the rapid development of electronic information technology and the widespread application of intelligent electronic devices, higher requirements are placed on the safety, energy density and environmental adaptability of energy storage devices. Zinc-air batteries have a high theoretical energy density (1086Whkg -1 ), environmentally friendly, rich anode materials and pollution-free. Low cost and high safety indicate that zinc-air batteries will occupy an important position in the future new energy storage system. However, the solid electrolyte of existing zinc-air batteries freezes at low temperatures, resulting in performance degradation and shortened life, which seriously affects the further application of zinc-air batteries. Therefore, it is very necessary to provide a low-temperature solid electrolyte to solve the problem that the existing solid electrolyte freezes at low temperatures, resulting in a decrease in conductivity and an increase in internal resistance, so that zinc-air batteries can meet the needs of industrial production. Summary of the invention

[0003] In order to solve the problem that the existing solid electrolyte freezes under low temperature conditions, resulting in decreased conductivity and increased internal resistance, the present invention provides a low-temperature solid electrolyte and a preparation method and application thereof.

[0004] The technical solution of the present invention:

[0005] One of the purposes of the present invention is to provide a method for preparing a low-temperature solid electrolyte, the method comprising the following steps:

[0006] (1) firstly mixing a polymer solution, a zwitterion solution and a zinc salt solution, then sequentially adding an initiator and a crosslinking agent, stirring evenly and then heating for crosslinking to obtain a hydrogel;

[0007] (2) The hydrogel is placed in an electrolyte solution and taken out after adsorption saturation to obtain a solid electrolyte.

[0008] It is further defined that the solute of the polymer solution is polyacrylamide or polyvinyl alcohol, and the solvent is deionized water.

[0009] It is further defined that the mass ratio of the solute to the solvent in the polymer solution is 1:(1-50).

[0010] It is further defined that the solute of the zwitterionic solution is L-proline or [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide, and the solvent is deionized water.

[0011] It is further defined that the mass ratio of the solute to the solvent of the zwitterionic solution is 1:(5-50).

[0012] It is further defined that the solute of the zinc salt solution is zinc perchlorate, zinc chloride, zinc tetrafluoroborate or zinc acetate, and the solvent is deionized water.

[0013] It is further defined that the mass ratio of the solute to the solvent in the zinc salt solution is 1:(1-10).

[0014] It is further defined that the molar ratio of the polymer, the zwitterion and the zinc salt is 1:(5-20):(2-10).

[0015] It is further defined that the initiator is ammonium persulfate or potassium persulfate, which is added to the mixed solution at a mass ratio of 0.1 to 2%.

[0016] It is further defined that the cross-linking agent is N,N-dimethylformamide or divinylbenzene, which is added to the mixed solution at a mass ratio of 0.1 to 1%.

[0017] It is further defined that the heating cross-linking temperature is 0 to 100° C. and the time is 2 to 8 hours.

[0018] It is further defined that the electrolyte solution is a mixed solution of potassium hydroxide and zinc acetate, wherein the concentration of potassium hydroxide is 1 to 12 mol / L, and the concentration of zinc acetate is 0.2 to 0.4 mol / L.

[0019] It is further defined that the hydrogel is immersed in the electrolyte solution for 24 to 72 hours.

[0020] A second object of the present invention is to provide a low-temperature solid electrolyte obtained by the above preparation method.

[0021] It is further defined that the low temperature solid electrolyte is used to prepare a flexible zinc-air battery.

[0022] The third object of the present invention is to provide a flexible zinc-air battery, which is assembled from the above-mentioned low-temperature solid electrolyte, a pretreated zinc sheet and a carbon cloth coated with an air electrode catalyst.

[0023] Beneficial effects:

[0024] The present invention introduces zinc salt and zwitterion into polymer to simply and quickly construct a solid electrolyte material with high ionic conductivity and low temperature resistance. The material is used in zinc-air batteries. At a low temperature of -40°C, it can be cycled for more than 270 hours, and the charge and discharge voltage of the battery remains unchanged, with good electrochemical stability. At the same time, it has the characteristics of high safety and low pollution, simple operation method, low cost, and universality. It is a new type of quasi-solid electrolyte that can meet the needs of industrial production of zinc-air batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The solid electrolyte assembled battery prepared in Example 1 was heated at -40°C and 0.5 mA cm -2 The long cycle diagram below;

[0026] Figure 2 The solid electrolyte assembled battery prepared in Comparative Example 1 was heated at -40 °C and 0.5 mA cm -2 The long cycle diagram below;

[0027] Figure 3 This is a physical picture of the open circuit voltage of the solid electrolyte assembled battery prepared in Example 1 at room temperature;

[0028] Figure 4 This is a physical picture of the open circuit voltage of the solid electrolyte assembled battery prepared in Comparative Example 1 at room temperature;

[0029] Figure 5 The open circuit voltage of the solid electrolyte assembled battery prepared in Example 1 at -40°C;

[0030] Figure 6 The open circuit voltage of the solid electrolyte assembled battery prepared in Comparative Example 1 at -40°C;

[0031] Figure 7 A schematic diagram of the structure of a zinc-air battery;

[0032] Figure 8 This is a SEM photo of the solid electrolyte prepared in Example 1;

[0033] Fig. 9 This is a SEM photograph of the solid electrolyte prepared in Comparative Example 1. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0037] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0038] Embodiment 1:

[0039] Step 1: dissolve 8 g of polyacrylamide in 10 mL of deionized water and stir until completely dissolved to obtain a polyacrylamide solution;

[0040] Step 2: Dissolve 3 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide in 10 mL of deionized water and stir until completely dissolved to obtain a zwitterionic solution;

[0041] Step 3, dissolve 4 g of zinc perchlorate in 10 mL of deionized water and stir until completely dissolved to obtain a zinc perchlorate solution;

[0042] Step 4: Mix the polyacrylamide solution obtained in step 1, the zwitterion solution obtained in step 2, and the zinc perchlorate solution obtained in step 3, and heat the mixture at a speed of 1000 r / min. -1 Under the conditions, the mixture was stirred for 30 min to form solution A;

[0043] Step 5: Add 0.02 g N,N-dimethylformamide and 0.2 g ammonium persulfate to solution A and stir at a speed of 500 rmin. -1 The mixture was stirred for 30 min under the conditions and kept warm at 60°C in an air atmosphere for 14 h to obtain a hydrogel polymer.

[0044] Step 6: Soak the obtained hydrogel polymer in a mixed strong alkaline solution of 6M potassium hydroxide and 0.2M zinc acetate for 48 hours to obtain a solid electrolyte.

[0045] The surface microstructure of the obtained solid electrolyte was characterized. Figure 8 As shown by Figure 8 It can be seen that the solid electrolyte presents a highly porous microstructure, which is due to the ionic coordination and charge complementation between zinc perchlorate, acrylamide and zwitterions, which leads to the formation of a pore structure. The rich and irregular pores act as a reservoir for the electrolyte, providing space for the interaction between the functionalized solid electrolyte and the zinc anode.

[0046] Step 7: Assembly and performance test of zinc-air battery: The polished zinc sheet and the carbon cloth coated with air electrode catalyst are assembled with the hydrogel electrolyte in step 6 into a flexible zinc-air battery. Figure 7 shown.

[0047] The solid electrolyte prepared in this embodiment is used as the electrolyte to assemble the zinc-air battery to carry out low temperature charge and discharge cycle performance test. The results are as follows: Figure 1 and Figure 3 , Figure 5 As shown, at -40°C and 0.5 mA cm -2 When tested under current density conditions, the battery cycle time reached more than 270 hours, showing good cycle performance. The open circuit voltage was 1.421V at room temperature and 1.33V at -40°C.

[0048] Comparative Example 1:

[0049] The difference between this embodiment and embodiment 1 is that zinc perchlorate solution is not added in the preparation of solution A, and other process steps and parameter settings are the same as those in embodiment 1. The specific operation process is as follows:

[0050] Step 1: Dissolve 6 g of polyacrylamide in 10 mL of deionized water and stir until completely dissolved to obtain a polyacrylamide solution;

[0051] Step 2: Dissolve 2 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide in 10 mL of deionized water and stir until completely dissolved to obtain a zwitterionic solution;

[0052] Step 3: Mix the polyacrylamide solution of step 1 and the zwitterion solution of step 2 at a speed of 1000 r min -1 , stirring for 30 minutes to form solution A;

[0053] Step 4: Add 0.02 g N,N-dimethylformamide and 0.2 g ammonium persulfate to solution A and stir at a speed of 500 rmin. -1 , stirred for 30 minutes, and placed in an air atmosphere at 60°C for 3 hours to obtain a solid electrolyte.

[0054] Step 5: Soak the obtained hydrogel polymer in a mixed strong alkaline solution of 6M potassium hydroxide and 0.2M zinc acetate for 48 hours to obtain a solid electrolyte.

[0055] The surface microstructure of the obtained solid electrolyte was characterized. Fig. 9 As shown by Fig. 9It can be seen that compared with the solid electrolyte without zinc perchlorate, the solid electrolyte with zinc perchlorate has more surface pores, which improves the swelling properties of the hydrogel, is conducive to storing more electrolytes, and provides space for the interaction between the functionalized solid electrolyte and the zinc anode.

[0056] Step 6: Assembly and performance test of zinc-air battery: The polished zinc sheet and the carbon cloth coated with air electrode catalyst are assembled with the hydrogel electrolyte in step 5 into a flexible zinc-air battery, such as Figure 7 shown.

[0057] The solid electrolyte prepared in this embodiment is used as the electrolyte to assemble the zinc-air battery to carry out low temperature charge and discharge cycle performance test. The results are as follows: Figure 2 and Figure 4 , Figure 6 As shown, at -40°C and 0.5 mA cm -2 Under current density conditions, the battery cycle time reached 170h, showing good cycle performance. The open circuit voltage was 1.344V at room temperature and 1.28V at -40℃.

[0058] By comparing the cycle time of the zinc-air battery assembled in Example 1 and Comparative Example 1 at low temperature, it can be seen that the cycle time of the solid electrolyte prepared by using zinc perchlorate is increased by 58.8% compared with that without using zinc perchlorate. This is mainly due to the ion coordination and charge complementation between zinc perchlorate and acrylamide and zwitterions, which leads to the formation of pore structure and improves the adsorption, ion conductivity and diffusion capacity of the electrolyte. This structural change helps to improve the ion transmission efficiency and electrochemical performance of the battery in a low temperature environment.

[0059] Although the present invention has been disclosed as above in the preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a low-temperature solid electrolyte, characterized in that: include: (1) firstly mix a polymer solution, a zwitterion solution and a zinc salt solution, wherein the molar ratio of the polymer, the zwitterion and the zinc salt is 1:(5-20):(2-10), then sequentially add an initiator and a cross-linking agent, stir evenly and heat to cross-link to obtain a hydrogel polymer; The solute of the polymer solution is polyacrylamide, and the solvent is deionized water. The polyacrylamide is dissolved in the deionized water and stirred until it is completely dissolved to obtain a polymer solution. The solute of the zwitter ion solution is [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonate propyl)ammonium hydroxide, and the solvent is deionized water. [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonate propyl)ammonium hydroxide is dissolved in deionized water and stirred until completely dissolved to obtain a zwitter ion solution. The solute of the zinc salt solution is zinc perchlorate, and the solvent is deionized water. The zinc perchlorate is dissolved in the deionized water and stirred until it is completely dissolved to obtain a zinc salt solution; The initiator is ammonium persulfate or potassium persulfate, and the cross-linking agent is N,N-dimethylformamide; The obtained polymer solution, the obtained zwitterion solution and the obtained zinc salt solution are mixed and stirred to form a solution A; Add N,N-dimethylformamide to solution A, stir, and keep warm in an air atmosphere to obtain a hydrogel polymer; (2) placing the hydrogel polymer in an electrolyte solution and taking it out after adsorption saturation to obtain a solid electrolyte; The electrolyte solution is a mixed solution of potassium hydroxide and zinc acetate, wherein the concentration of potassium hydroxide is 1-12 mol / L, and the concentration of zinc acetate is 0.2-0.4 mol / L; the immersion time is 24-72 h.

2. The preparation method according to claim 1, characterized in that: The mass ratio of solute to solvent in the polymer solution is 1:(1~50).

3. The preparation method according to claim 1, characterized in that: The mass ratio of solute to solvent in zwitterionic solution is 1:(5~50).

4. The preparation method according to claim 1, characterized in that: The mass ratio of solute to solvent in the zinc salt solution is 1:(1~10).

5. The preparation method according to claim 1, characterized in that: The initiator is added to the mixed solution at a weight ratio of 0.1-2%; the cross-linking agent is added to the mixed solution at a weight ratio of 0.1-1%.

6. The preparation method according to claim 1, characterized in that: The heating cross-linking temperature is 0~100℃ and the time is 2~8h.

7. A low-temperature solid electrolyte prepared by the method according to any one of claims 1 to 6.

8. A flexible zinc-air battery, characterized in that: The method is assembled from the low-temperature solid electrolyte according to claim 7, a pretreated zinc sheet and a carbon cloth coated with an air electrode catalyst.

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