Polymer gel electrolyte for zinc ion battery, preparation method and zinc ion battery

Abstract

The invention discloses a polymer gel electrolyte for a zinc ion battery, a preparation method and the zinc ion battery, and belongs to the technical field of electrochemical energy storage. Each gram of the polymer gel electrolyte comprises 0.1-0.3 g of polyacrylamide gel, a high-electronegativity fluorine substance uniformly distributed in the gel and zinc salt, and the mass ratio of fluorine in the gel is 0.1-10%. According to the fluorine-containing additive, the zinc ion solvation structure and the interface deposition behavior are effectively regulated and controlled through the strong electronegativity characteristic, a stable protection layer is formed on the surface of the zinc negative electrode, and dendritic crystal growth and corrosion reaction are remarkably inhibited.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, specifically relating to a polymeric gel electrolyte for zinc-ion batteries, its preparation method, and the zinc-ion battery itself. Background Technology

[0002] Aqueous zinc-ion batteries are considered strong contenders for next-generation large-scale energy storage systems due to their high safety, low cost, and environmental friendliness. However, problems such as dendrite growth, hydrogen evolution corrosion, and surface passivation of zinc metal anodes in aqueous environments severely limit their cycle life and commercial applications. Gel polymer electrolytes (GPEs), however, can avoid the leakage problems of liquid electrolytes and combine the functions of both electrolyte and separator. Through hydrogen bonding between hydrophilic polymers and free water molecules, they help improve the interface problems of zinc anodes. Currently common GPEs include natural polymer gels such as chitosan and cellulose derivatives, which have good biocompatibility, environmental friendliness, and abundant resources, but usually suffer from insufficient mechanical strength and poor electrochemical stability. In contrast, synthetic polymer gels, represented by polyacrylamide (PAM), exhibit unique advantages. However, traditional PAM gel electrolytes have limited ability to regulate the interface chemistry of zinc anodes; their hydrophilic amide groups, when combined with water molecules, are insufficient to effectively prevent water corrosion of the zinc anode, and their simple physical network structure is difficult to guide uniform zinc ion deposition. Summary of the Invention

[0003] This invention proposes a zinc-ion battery with a gel electrolyte containing a strong electronegative fluorine additive. By introducing fluorine-containing substances, the positive regulatory effect of fluorine on the deposition behavior and solvation structure of zinc ions is verified and utilized from two dimensions: chemical composition and electrochemical interface. This collaboratively solves the problems of dendrite growth and side reactions in zinc-ion batteries.

[0004] The core of this invention lies in its unique electrolyte composition. This electrolyte is a copolymer formed by cross-linking a gel containing a large number of hydrogen bonds and possessing good molecular structure and chain segment mobility with a highly electronegative substance, through chemical reactions between cross-linking agents, free radicals, or functional groups to form chemical bonds. This electrolyte combination not only endows the battery with good mechanical properties but also optimizes interfacial ion transport. Specifically, each 1g of electrolyte contains at least 0.6~0.9g of hydrogen-bonded polymeric gel (such as PAM gel electrolyte), and these gel molecules are interconnected by hydrogen bonds to construct a stable three-dimensional network structure; at the same time, the electrolyte also contains 0.02~0.3g of a highly electronegative fluorine substance, such as boron trifluoride diethyl ether adduct (chemical formula BF3·(C2H5)2O), etc.

[0005] The present invention also modifies the polymer gel electrolyte by different fluorine-containing additives. The results show that the introduction of fluorine, which has a strong electronegativity, can significantly improve the cycle life of the battery and inhibit the growth of zinc dendrites. Fluorine additives can preferentially adsorb on the zinc surface to form an ordered hydrophobic layer, thereby effectively inhibiting hydrogen evolution reaction and zinc corrosion.

[0006] Based on the above analysis, the strongly electronegative fluorine-added gel electrolyte of this invention enhances interfacial stability through fluorine-containing additives and is synergistically assembled with vanadium pentoxide cathode material and zinc anode to construct a zinc-ion battery. This battery exhibits excellent electrochemical performance, combining high energy density, long cycle life, and superior safety. It also achieves self-healing electrolyte functionality and battery biodegradability, providing a new technological path for environmentally friendly, high-performance energy storage devices and possessing broad application prospects. This battery is not only suitable for portable electronic devices and electric vehicles but can also serve as a key component of energy storage systems, providing strong support for the efficient utilization of renewable energy. Attached Figure Description

[0007] Figure 1 The CA curves for PAM and PAM / BFEE, PAM / NaF, PAM / PFOA, and PAM / LITFSI gel electrolytes in embodiments of the present invention are shown.

[0008] Figure 2 CA curves of gel electrolytes with different NaF concentrations are shown. Detailed Implementation

[0009] To further understand the purpose, content, and advantages of this invention, specific embodiments of the invention are described in detail below. However, these embodiments are not limited to the examples described below and should be freely combined according to actual circumstances. The endpoints and values ​​of the ranges disclosed herein are not limited to the precise ranges and values. For numerical ranges, endpoint values ​​of various ranges, endpoint values ​​of various ranges and individual point values, and individual point values ​​can be combined to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0010] The present invention will be further described in detail below with reference to the embodiments: This invention provides a polymeric gel electrolyte for zinc-ion batteries. Each gram of electrolyte comprises 0.1-0.3g of polyacrylamide gel, a strongly electronegative fluorine substance uniformly distributed in the gel, and a zinc salt. The fluorine content in the gel is 0.1-10% by mass. The use of fluorine-containing additives effectively enhances interfacial stability. In synergistic assembly with vanadium pentoxide cathode material and zinc anode, a zinc-ion battery is constructed, exhibiting excellent electrochemical performance, high energy density, long cycle life, and excellent safety. Simultaneously, it achieves self-healing function of the electrolyte and biodegradability of the battery.

[0011] In some implementations, the strongly electronegative fluorine substance is selected from any one or more of boron trifluoride ether adduct, NaF, ammonium perfluorooctanoate, and lithium bis(trifluoromethanesulfonyl)imide.

[0012] In some embodiments, a method for preparing a polymeric gel electrolyte for zinc-ion batteries is also provided, comprising the following steps: mixing acrylamide, a strongly electronegative fluorine substance and a zinc salt in water to form a precursor solution, and then adding a crosslinking agent and an initiator and initiating polymerization at room temperature.

[0013] In some embodiments, the mass ratio of the strongly electronegative fluorine substance to acrylamide is 1:100 to 1:5.67, for example, 1:100, 1:50, 1:20, etc.

[0014] In some preferred embodiments, the mass ratio of the strongly electronegative fluorine substance to acrylamide is 1:50 to 1:20.

[0015] In some preferred embodiments, the strongly electronegative fluorine substance is NaF, and the mass ratio of NaF to acrylamide is 1:75~150.

[0016] In some preferred embodiments, the strongly electronegative fluorine substance is NaF, and the mass ratio of NaF to acrylamide is 1:75~100.

[0017] In some embodiments, the crosslinking agent is N,N'-methylenebisacrylamide, the initiator is potassium persulfate, and the mass ratio of acrylamide, potassium persulfate, and N,N'-methylenebisacrylamide is 3:0.03:0.0015.

[0018] The present invention will be further described in detail below with reference to more specific embodiments. Example 1: Preparation and Battery Performance Optimization of Electrolyte Modified with Boron Trifluoride Diethyl Ether Adduct

[0019] 1. Electrolyte preparation: Raw material preparation: Weigh 3g of acrylamide (AM) and transfer 52μL of boron trifluoride diethyl ether adduct (BFEE) as the main component of the electrolyte.

[0020] Mixing and polymerization: Add the two raw materials mentioned above to a beaker, add a small amount of deionized water (e.g., 10 ml) and stir at high speed to form a homogeneous mixture. Then add 5.75 g of ZnSO4·7H2O to the mixture and stir for 30 minutes. Subsequently, add 30 mg of initiator (e.g., ammonium persulfate APS) and 1.5 mg of crosslinking agent (e.g., N,N'-methylenebisacrylamide MBAA) and stir continuously to allow the mixture to undergo chemical polymerization (the reaction temperature is generally room temperature, e.g., 10~30℃, 20℃ in this example) to form a network gel electrolyte and inject the mixture into a mold.

[0021] Post-processing: The obtained mold was placed in a vacuum drying oven (60~80℃) to initially obtain a composite gel of BFEE (PAM / BFEE).

[0022] 2. Cathode preparation: Raw material preparation: Weigh a certain amount of commercial vanadium pentoxide (V2O5).

[0023] Electrode preparation: Vanadium pentoxide powder is mixed with a conductive agent (such as acetylene black) and a binder (such as polytetrafluoroethylene PTFE, PVDF) in a certain proportion, and an appropriate amount of solvent (such as N-methylpyrrolidone NMP) is added. The mixture is then ground thoroughly in a ceramic mortar until a uniform slurry is formed. The slurry is then uniformly coated onto a current collector (such as aluminum foil, stainless steel mesh), and then dried in a vacuum drying oven and pressed into a sheet to obtain the positive electrode.

[0024] 3. Anode preparation: Material selection: High-purity zinc sheets are selected as the negative electrode.

[0025] Post-processing: Clean and dry the zinc sheets to ensure that their surface is clean and free of impurities.

[0026] 4. Battery assembly: Structure: The prepared positive electrode, negative electrode and gel electrolyte are assembled into a sandwich structure in sequence and encapsulated in a flexible battery case.

[0027] Sealing: Heat sealing technology is used to seal the battery casing, ensuring no leakage inside the battery.

[0028] 5. Performance Testing: Electrochemical workstation testing: CA testing was performed on PAM and PAM / BFEE gel electrolytes. Figure 1 This study verified the impact of BFEE modification on battery performance. Specifically, compared to the pure PAM gel electrolyte system, the modified gel electrolyte showed higher Zn content in the PAM / BFEE composite gel. 2+ The 2D diffusion duration was significantly shortened, indicating that the introduction of BFEE additives effectively regulated the Zn... 2+ The diffusion behavior promotes its uniform distribution, thereby suppressing dendrite growth caused by local concentration polarization and significantly improving the stability of the electrode / electrolyte interface. Example 2: Preparation of sodium fluoride modified electrolyte and optimization of battery performance

[0029] 1. Electrolyte modification: Raw material preparation: Following the steps in Example 1, the additive was changed to 0.03g NaF.

[0030] Mixing and polymerization: Mixing and polymerization were carried out according to the steps of Example 1.

[0031] 2. Battery assembly: Assembly: Assemble the battery according to the steps in Example 1.

[0032] 3. Performance Testing: Electrochemical performance testing: CA testing of PAM and PAM / NaF gel electrolyte ( Figure 1 Test results show that the introduction of NaF makes Zn The 2D diffusion time was significantly reduced, indicating that the NaF additive effectively optimized the Zn diffusion. Diffusion kinetics. Example 3: Preparation and Battery Performance Optimization of Perfluorooctanoic Acid (PFOA) Modified Electrolyte

[0033] 1. Electrolyte modification: Raw material preparation: Following the steps in Example 1, the additive was changed to 0.1g PFOA.

[0034] Mixing and polymerization: Mixing and polymerization were carried out according to the steps of Example 1.

[0035] 2. Battery assembly: Assembly: Assemble the battery according to the steps in Example 1.

[0036] 3. Performance Testing: Electrochemical performance testing: CA testing was performed on PAM and PAM / PFOA gel electrolytes. Figure 1 Data shows that PFOA-modified Zn The 2D diffusion time was significantly shortened, confirming the effect of PFOA on Zn. Diffusion behavior has a positive regulatory effect. Example 4: Preparation of electrolyte and optimization of battery performance modified with lithium bis(trifluoromethanesulfonylimide) (LITFSI).

[0037] 1. Electrolyte modification: Raw material preparation: Following the steps of Example 1, the additive was changed to 0.15g LITFSI.

[0038] Mixing and polymerization: Mixing and polymerization were carried out according to the steps of Example 1.

[0039] 2. Battery assembly: Assembly: Assemble the battery according to the steps in Example 1.

[0040] 3. Performance Testing: Electrochemical performance testing: CA testing was performed on PAM and PAM / LiTFSI gel electrolytes. Figure 1 The results showed that the addition of LiTFSI significantly shortened the Zn... The 2D diffusion time indicates that LiTFSI effectively guides Zn. The diffusion path is optimized to improve its deposition behavior.

[0041] This invention contains a highly electronegative additive that preferentially adsorbs onto the zinc anode surface, forming a stable interface layer that effectively blocks direct contact between water molecules and Zn, while simultaneously guiding uniform zinc ion deposition. Specifically, it significantly shortens the 2D diffusion process of zinc ions, promoting lateral zinc ion growth rather than vertical zinc dendrite growth, thus focusing on solving deposition kinetics issues. Among the four embodiments mentioned above, NaF is the optimal choice. Figure 1 Among them, the gel electrolyte modified with NaF is superior to those modified with other additives such as Zn. 2+ The 2D diffusion duration is significantly shortened, where diffusion occurs in three dimensions (3D), promoting zinc deposition and dendrite formation. Example 5

[0042] Based on Example 2, only the amount of NaF was adjusted while other conditions remained unchanged. Modification was achieved by adding 0.01, 0.02, and 0.04 g of NaF, respectively. Figure 2 It can be seen that the performance is optimal when the amount of NaF added is 0.03g.

[0043] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

Claims

1. A polymeric gel electrolyte for zinc-ion batteries, characterized in that, Each gram of electrolyte contains 0.1~0.3g of polyacrylamide gel, a strongly electronegative fluorine substance uniformly distributed in the gel, and zinc salt, with fluorine accounting for 0.1~10% of the gel by mass.

2. The polymeric gel electrolyte for zinc-ion batteries according to claim 1, characterized in that, The strongly electronegative fluorine substance is any one or more of boron trifluoride diethyl ether adduct, NaF, ammonium perfluorooctanoate, and lithium bis(trifluoromethanesulfonylimide).

3. The method for preparing a polymeric gel electrolyte for zinc-ion batteries as described in claim 1, characterized in that, The process includes the following steps: mixing acrylamide, a strongly electronegative fluorine substance, and zinc salt in water to form a precursor solution, then adding a crosslinking agent and an initiator and initiating polymerization at room temperature.

4. The method for preparing a polymeric gel electrolyte for zinc-ion batteries as described in claim 3, characterized in that, The mass ratio of the strongly electronegative fluorine substance to acrylamide is 1:100 to 1:5.

67.

5. The method for preparing a polymeric gel electrolyte for zinc-ion batteries as described in claim 3, characterized in that, The mass ratio of the strongly electronegative fluorine substance to acrylamide is 1:50 to 1:

20.

6. The method for preparing a polymeric gel electrolyte for zinc-ion batteries as described in claim 3, characterized in that, The strongly electronegative fluorine substance is NaF, and the mass ratio of NaF to acrylamide is 1:75~150.

7. The method for preparing a polymeric gel electrolyte for zinc-ion batteries as described in claim 3, characterized in that, The strongly electronegative fluorine substance is NaF, and the mass ratio of NaF to acrylamide is 1:75~100.

8. The method for preparing a polymeric gel electrolyte for zinc-ion batteries as described in claim 3, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide, and the initiator is potassium persulfate. The mass ratio of acrylamide, potassium persulfate, and N,N'-methylenebisacrylamide is 3:0.03:0.0015.

9. A zinc-ion battery, characterized in that, The electrolyte of the battery is the polymeric gel electrolyte as described in claim 1 or 2.

10. The zinc-ion battery according to claim 9, characterized in that, The positive electrode active material is vanadium pentoxide, and the negative electrode is zinc.

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