Method for modifying gel electrolyte by using zwitterionic additive

Abstract

The invention discloses a zwitterionic additive modified gel electrolyte applied to a zinc ion battery or a zinc ion hybrid supercapacitor. The preparation method comprises the following steps: by taking an acrylamide monomer as a raw material, adding the zwitterionic additive into the system, and carrying out the processes of photo-initiation polymerization, electrolyte soaking and the like, thereby obtaining the zwitterionic additive modified gel electrolyte. Assembling the obtained gel electrolyte into a ZnZn symmetric battery, a ZnCu asymmetric battery and a ZnTi asymmetric battery, and carrying out electrochemical performance test to obtain a polarization voltage curve, a coulombic efficiency curve and nucleation overpotential; meanwhile, a soft package battery based on the gel electrolyte is assembled and subjected to an electrochemical performance test, the test current density is 0.1-50 A g <-1 >, and the voltage range is 0.2-1.8 V or 0.9-1.8 V. The preparation method is simple, the synthesized gel electrolyte has good mechanical properties and electrochemical properties, and the assembled zinc ion battery or zinc ion supercapacitor shows good electrochemical stability.

Description

Technical Field

[0001] The present invention belongs to the field of electricity storage materials, and particularly relates to a gel electrolyte modified by zwitterionic additives and applied to zinc-ion batteries or zinc-ion hybrid supercapacitors. Background Art

[0002] With the development of portable electronic devices, it is particularly important to develop new and efficient energy storage devices. Although lithium-ion batteries, as widely used commercial batteries, have advantages such as high energy density, etc., the limited reserves of lithium resources, high cost, and insufficient safety of organic electrolytes seriously limit the application of zinc-ion batteries in portable electronic devices. Therefore, the research and development of new aqueous ion energy storage devices have attracted the interest of more and more researchers.

[0003] Aqueous zinc-ion energy storage devices (ZSDs) have the characteristics of large reserves of zinc resources, high safety, high theoretical capacity, high energy density, etc., and have good application prospects. However, ZSDs have problems such as the growth of zinc dendrites, electrolyte leakage, evaporation of liquid aqueous electrolytes, etc. Although conventional hydrogel electrolytes can inhibit the growth of zinc dendrites, reduce side reactions, and alleviate the evaporation of electrolytes, problems such as low ionic conductivity, poor electrochemical stability, and poor mechanical strength seriously restrict their practical applications. Therefore, the development of gel electrolytes with good mechanical properties and electrochemical properties plays an important role in the commercial application of ZSDs. Research shows that introducing different charged groups or functional groups into the gel electrolyte can optimize the ionic conductivity, mechanical strength, and interfacial adhesion of the gel electrolyte, thereby achieving an improvement in electrochemical performance. Therefore, it is important to explore new synthesis methods for improving the comprehensive performance of gel electrolytes.

[0004] Zwitterionic additives contain adjustable functional groups with positive and negative charged groups. By introducing zwitterions, the zincophilicity of the gel electrolyte can be improved, and the migration process and desolvation process of solvated zinc ions can be optimized. The zincophilic groups in zwitterions can transition sites and promote the migration of zinc ions. At the same time, the zincophilic groups on the anode can inhibit the diffusion of zinc ions, thereby inhibiting the formation of zinc dendrites and the occurrence of side reactions. The gel electrolyte obtained by modifying with zwitterionic additives shows good electrochemical performance when applied to ZSDs and has great application potential. Summary of the Invention

[0005] The purpose of the present invention is to provide a gel electrolyte modified by zwitterionic additives and applied to zinc-ion batteries or zinc-ion hybrid supercapacitors.

[0006] The preparation method of the zwitterionic additive modified gel electrolyte provided by the present invention is as follows: at room temperature, acrylamide monomer, N-N'-methylenebisacrylamide crosslinking agent, initiator and zwitterion A are sequentially added to deionized water and stirred until a uniform transparent solution is formed, and then polymerization is initiated to form a zwitterion-added A / PAAm hydrogel. Finally, the synthesized hydrogel is immersed in an electrolyte solution for a period of time to form a hydrogel electrolyte. Among them, the zwitterion A is lauryl betaine, proline, glycine, lysine, tryptophan, dopamine, 2-morpholinoethanesulfonic acid, 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid; in the mixture, the mass ratio of zwitterion A to monomer is 1:100 to 1:1 in sequence; the mass ratio of crosslinking agent to monomer is 1:1000 to 1:5000 in sequence.

[0007] In the mixture, the mass ratio of zwitterion A to monomer is preferably 1:40 to 1:5. The mass ratio of crosslinking agent to monomer is preferably 1:2000 to 1:3000. The polymerization initiation method is preferably photoinitiation.

[0008] The present invention conducts electrochemical tests on the prepared hydrogel electrolyte and evaluates the charge-discharge performance of the ZSDs assembled therefrom.

[0009] The present invention uses acrylamide as the monomer, N-N'-methylenebisacrylamide as the crosslinking agent, and lauryl betaine as the zwitterionic additive, adds them to deionized water and stirs until a uniform transparent solution is formed, and then uses ultraviolet light irradiation for photoinitiated polymerization to form a zwitterion A / PAAm double-crosslinked hydrogel. The synthesized hydrogel is immersed in an electrolyte solution to form a zwitterion-modified hydrogel electrolyte. However, when the zwitterion is not added, the obtained unmodified gel electrolyte will have problems such as low mechanical strength, low ionic conductivity, and poor interfacial adhesion, indicating that this method can optimize the electrochemical and mechanical properties of the hydrogel electrolyte by regulating the mass ratio of zwitterion to monomer. The method provided by the present invention has the advantages of simple operation and non-toxic raw materials. By introducing zwitterionic additives, the obtained hydrogel has good mechanical properties and interfacial adhesion ability. The hydrogel electrolyte network structure based on it can improve electrochemical properties such as solution conductivity and zinc ion transference number. Thanks to these advantages, the prepared hydrogel electrolyte is a new type of electrolyte with high performance, which can improve problems such as the generation of zinc dendrites, electrolyte leakage, and evaporation of liquid aqueous electrolytes encountered in the development of ZSDs, and effectively promotes the development of ZSDs. Description of the Drawings

[0010] Figure 1 Polarization voltage curve of the Zn||Zn symmetric battery of the sample prepared in Example 1.

[0011] Figure 2 Ionic conductivity of the sample prepared for Example 1.

[0012] Figure 3 Plasticity photograph of the sample prepared for Example 1. Embodiment Example

[0013] At room temperature, 3.84 g of acrylamide monomer, 1.15 mg of N,N'-methylenebisacrylamide crosslinker, 0.115 g of ultraviolet initiator, and 0.48 g of lauryl betaine were weighed and successively added to 20 mL of deionized water and stirred for 30 minutes to obtain a homogeneous and transparent solution. Polymerization was carried out under ultraviolet light (wavelength 365 nm, intensity 8 W) irradiation for 1 hour to form a lauryl betaine / PAAm hydrogel. Finally, the obtained hydrogel was immersed in 1 M Zn(CF 3 SO 3 ) 2 aqueous solution for 12 hours to form a hydrogel electrolyte.

Claims

1. A method for modifying a gel electrolyte with zwitterionic additives, the specific steps are as follows: At room temperature, acrylamide monomer, N-N′ methylene bisacrylamide crosslinking agent, ultraviolet light initiator and zwitterion A are successively added to deionized water and stirred until a uniformly transparent solution is formed. Subsequently, photoinitiated polymerization is carried out for 1 h under the irradiation of ultraviolet light (wavelength 365 nm, intensity 8 W) to form a zwitterion A / PAAm double-crosslinked hydrogel. Finally, the synthesized hydrogel is immersed in 1 M Zn(CF 3 SO 3 ) 2 aqueous solution for 12 h to form a hydrogel electrolyte. Among them, the zwitterion A is lauryl betaine, proline, glycine, lysine, tryptophan, dopamine, 2-morpholinoethanesulfonic acid, 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid; in the mixture, the mass ratio of the zwitterion A to the monomer is successively 1:40 to 1:5; the mass ratio of the crosslinking agent to the monomer is successively 1:2000 to 1:3000.

2. According to the method described in claim 1, it is characterized in that: the zwitterion is lauryl betaine, proline, glycine, lysine, tryptophan, dopamine, 2-morpholinoethanesulfonic acid, 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid.

3. According to the method described in claims 1 to 2, it is characterized in that: the mass ratio of the zwitterion A to the acrylamide monomer is successively 1:100 to 1:

1.

4. According to the method described in claims 1 to 3, it is characterized in that: the initiation method of the polyacrylamide monomer is: photoinitiation, thermal initiation, etc.

5. According to the method described in claims 1 to 4, it is characterized in that: the polymer monomer is acrylamide, acrylic acid, vinylpyrrolidone, methacrylic acid.

6. According to the method described in claims 1 to 5, it is characterized in that: the ratio of the crosslinking agent to the monomer is 1:1000 to 1:5000.

7. The zwitterion additive-modified gel electrolyte prepared by the method described in any one of claims 1 to 6 is applied to a zinc-ion battery or a zinc-ion hybrid supercapacitor.

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