Method for constructing gel electrolyte on surface of electrode through in-situ self-initiation and application of method

Abstract

The invention relates to the technical field of gel electrolyte, in particular to a method for constructing gel electrolyte on the surface of an electrode through in-situ self-initiation and application of the method. The method comprises the following steps: (1) dissolving a zinc salt in water to obtain a liquid electrolyte; (2) uniformly mixing a gel monomer, an initiator, a cross-linking agent and a liquid electrolyte to obtain a precursor solution; and (3) pouring the precursor solution on the surface of the negative electrode of the battery, covering the precursor solution with the positive electrode of the battery, and standing to realize in-situ construction of the gel electrolyte on the surface of the electrode. The solution is gelatinized through reducibility self-initiation of the metal electrode and is constructed on the surface of the electrode in situ, the electrochemical performance of the aqueous zinc metal is remarkably improved, meanwhile, the process steps are reduced, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gel electrolyte, in particular, especially relates to a method for constructing gel electrolyte on electrode surface in situ self-initiation and application thereof. BACKGROUND

[0002] Water-based zinc metal batteries have the characteristics of low cost, high theoretical volume capacity, etc., and are considered as an effective candidate for the next generation of grid-level large-scale energy storage. However, there are problems such as hydrogen evolution reaction, corrosion, passivation and dendrite growth of the electrode in the water-based electrolyte, and in addition, the liquid electrolyte has the risk of leakage, which limits the further development and application of water-based zinc metal batteries.

[0003] Hydrogel electrolyte has solid-state characteristics and liquid-state ion transport mechanism, so it can effectively prevent the associated side reactions in the electrode reaction process. The main materials of the current hydrogel electrolyte are usually composed of polyacrylamide, polyacrylic acid, polyvinyl alcohol, biomass-based polysaccharide and biomass-based protein, and a simple stacking method is usually used in the battery assembly process. However, due to the solid-state physical properties of the hydrogel electrolyte, an electrode / electrolyte interface cavity is inevitably formed after the volume change of the electrode after multiple charge and discharge, resulting in a large interface mass transfer resistance. In addition, some hydrogel electrolytes require external additional energy during preparation, such as polyacrylamide and polyacrylic acid which require photo / thermal initiation, and polyvinyl alcohol which requires multiple freeze-thaw, which not only increases the process flow, but also increases the cost of large-scale production.

[0004] Therefore, it is of great significance to develop a more suitable gel electrolyte preparation method to solve the interface adaptability problem and the process problem. SUMMARY

[0005] In view of the poor interface adaptability of the current gel electrolyte, the present application provides a method for constructing gel electrolyte on electrode surface in situ self-initiation and application thereof. The gel is self-initiated on the electrode surface in situ by the reducing property of the zinc metal electrode, which eliminates the need for additional energy such as light and heat to initiate, and can effectively achieve full coverage of the gel on the electrode surface in situ, solve the problem of insufficient contact between the electrode and the electrolyte, enhance the affinity between the electrode and the electrolyte, delay the occurrence of interface side reactions, and reduce the risk of interface contact deterioration caused by electrode volume expansion.

[0006] To achieve the above technical purposes, the present application adopts the following technical solutions: The first aspect of the present application provides a method for constructing gel electrolyte on electrode surface in situ self-initiation, which comprises the following steps: (1) Dissolve zinc salt in water to obtain a liquid electrolyte; (2) Mix the gel monomer, initiator, crosslinking agent and liquid electrolyte to obtain a precursor solution; (3) Pouring the precursor solution on the surface of the negative electrode of the battery, covering the positive electrode of the battery onto the precursor solution and standing to realize in-situ construction of the gel electrolyte on the surface of the electrode.

[0007] Preferably, in step (1), the zinc salt is selected from one of zinc sulfate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate, zinc perchlorate, zinc chloride.

[0008] Preferably, in step (1), the concentration of the liquid electrolyte is 240-1200 g / L.

[0009] Preferably, in step (2), the gel monomer is one of acrylamide, acrylic acid and acrylamide derivatives. The crosslinking agent is one of N, N-dimethyl bisacrylamide, N, N'-(1,2-dihydroxyethyl) bisacrylamide and N, N'-bisacryloyl cystamine. The initiator is one of potassium persulfate, ammonium persulfate and 4-(2-hydroxy-3-phenylpropenyl) phenyl ketone.

[0010] Preferably, in step (2), the mass ratio of the gel monomer, the crosslinking agent, the initiator and the liquid electrolyte is 10-50:0.1-0.5:1-5:100-500.

[0011] Preferably, in step (3), the pouring amount of the precursor solution is 50-150 μL cm -2 ; The standing time is 1-24 hours.

[0012] The present application provides a gel electrolyte obtained by the method of in-situ self-initiation construction of gel electrolyte on the surface of the electrode.

[0013] The present application provides application of the above-mentioned gel electrolyte in aqueous zinc metal batteries.

[0014] The present application has the following advantages: 1. The present application realizes chemical initiation of the solution by the reducibility of the metal electrode to construct the gel electrolyte in-situ between the electrodes, significantly improves the electrochemical performance of the aqueous zinc metal, and reduces the process steps and cost.

[0015] 2. The gel electrolyte constructed by the method of the present application has the characteristics of inhibiting hydrogen evolution reaction on the electrode surface, delaying electrode corrosion and promoting uniform deposition of ions, and preventing the problem of deterioration of the electrode / electrolyte interface caused by volume expansion of the electrode during charging and discharging. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1A scanning electron microscope image of Example 1; Figure 2 A scanning electron microscope image of Example 2; Figure 3 A scanning electron microscope image of Example 3; Figure 4 A scanning electron microscope image of Comparative Example 1; Figure 5 A corrosion curve of Example 1; Figure 6 A corrosion curve of Example 2; Figure 7 A corrosion curve of Example 3; Figure 8 A corrosion curve of Comparative Example 1; Figure 9 A cycle performance graph of Example 1; Figure 10 A cycle performance graph of Example 2; Figure 11 A cycle performance graph of Example 3; Figure 12 A cycle performance graph of Comparative Example 1; Figure 13 A cycle efficiency graph of Example 1; Figure 14 A cycle efficiency graph of Example 2; Figure 15 A cycle efficiency graph of Example 3; Figure 16 A cycle efficiency graph of Comparative Example 1. DETAILED DESCRIPTION

[0017] The following examples can make the person skilled in the art more fully understand the present application, but in no way limit the present application.

[0018] Unless otherwise specified, the materials used in the examples of the present application can be obtained by commercial means or prepared according to conventional methods well known to those skilled in the art.

[0019] The following I2 / C cathode was prepared by the following method: I2, polytetrafluoroethylene and potassium carbonate were mixed in a mass ratio of 6:2:2, the mixture was dispersed in anhydrous ethanol, stirred at a speed of 400 rpm for 2 hours, then coated on a titanium mesh, and then dried in an oven at 30°C for 20 minutes to obtain the I2 / C cathode.

[0020] Comparative Example 1 (1) 78 g of zinc tetrafluoroborate was weighed, and after initial dissolution with deionized water, it was diluted to volume with a 100 mL volumetric flask to obtain a zinc tetrafluoroborate liquid electrolyte with a concentration of 780 g / L; (2) 0.005 g of crosslinking agent N, N-dimethylacrylamide, 3.6 g of gel monomer N, N-dimethylacrylamide and 0.06 g of initiator 4-(2-hydroxy-3-phenylacryl) phenyl ketone were added to 10 mL of the electrolyte solution obtained in step (1), and stirred for 6 hours to obtain a precursor solution; (3) The precursor solution was irradiated under ultraviolet light for 20 minutes to obtain a gel electrolyte; (4) The gel electrolyte after irradiation and curing was assembled with a zinc foil negative electrode (diameter 16 mm) and an I2 / C positive electrode (diameter 16 mm) to form a battery.

[0021] Example 1 (1) 78 g of zinc tetrafluoroborate was weighed, initially dissolved using deionized water, and then made up to volume in a 100 mL volumetric flask to obtain a zinc tetrafluoroborate liquid electrolyte with a concentration of 780 g / L; (2) 0.005 g of crosslinking agent N, N-dimethylacrylamide, 3.6 g of gel monomer N, N-dimethylacrylamide and 0.06 g of initiator 4-(2-hydroxy-3-phenylacryl) phenyl ketone were added to 10 mL of the liquid electrolyte obtained in step (1), and stirred for 6 hours to obtain a precursor solution; (3) 150 μL of the precursor solution was cast onto a zinc foil negative electrode (diameter 16 mm), and an I2 / C positive electrode (diameter 16 mm) was covered on the precursor solution and left to stand for 24 hours to construct a gel electrolyte in situ on the surface of the electrode.

[0022] Example 2 (1) 57 g of zinc sulfate was weighed, initially dissolved using deionized water, and then made up to volume in a 100 mL volumetric flask to obtain a zinc sulfate liquid electrolyte with a concentration of 0.57 g / mL; (2) 0.005 g of crosslinking agent N, N'-bisacryloyl cystamine, 5 g of gel monomer acrylamide and 0.06 g of initiator potassium persulfate were added to 10 mL of the liquid electrolyte obtained in step (1), and stirred for 6 hours to obtain a precursor solution; (3) 100 μL of the precursor solution was cast onto a zinc foil negative electrode (diameter 16 mm), and an I2 / C positive electrode (diameter 16 mm) was covered on the precursor solution and left to stand for 15 hours to construct a gel electrolyte in situ on the surface of the electrode.

[0023] Example 3 (1) 36.4 g of zinc trifluoromethanesulfonate was weighed, initially dissolved using deionized water, and then made up to volume in a 100 mL volumetric flask to obtain a zinc trifluoromethanesulfonate liquid electrolyte with a concentration of 364 g / L; (2) Add 0.005g of crosslinking agent N,N'-(1,2-dihydroxyethylidene)bisacrylamide, 6g of gel monomer acrylic acid and 0.08g of initiator ammonium persulfate to 10mL of the liquid electrolyte obtained in step (1), stir for 6 hours to obtain the precursor solution; (3) Pour 200 μL of precursor solution onto the I2 / C positive electrode (16 mm in diameter), cover the I2 / C positive electrode (16 mm in diameter) with the precursor solution and let it stand for 20 hours to achieve in-situ self-initiated construction of gel electrolyte on the electrode surface.

[0024] Results analysis: like Figures 1-4 As shown, the gel electrolytes constructed in situ in Examples 1-3 are in close contact with the zinc anode, indicating that the in-situ gel electrolyte construction method can enhance the electrode-electrolyte interface affinity. In Comparative Example 1, the electrolyte constructed using a non-in-situ method has a large gap between it and the electrode, leading to increased ion transport resistance.

[0025] like Figures 5-8 As shown, the in-situ gel electrolytes constructed in Examples 1-3 exhibit lower corrosion current density and higher corrosion potential. The in-situ surface gel electrolyte construction method can effectively reduce the corrosion rate and corrosion tendency of the zinc metal anode. In Comparative Example 1, the non-in-situ constructed electrolyte may lead to the presence of an interfacial water layer due to uneven contact, thereby exacerbating electrode corrosion.

[0026] like Figures 9-16 The electrochemical performance graphs show that the gel electrolytes constructed in situ in Examples 1-3 can achieve an electrochemical performance of 0.5 mA cm⁻¹. -2 The current density and 0.5 mAh cm⁻¹ -2 The electrolyte obtained in Comparative Example 1 exhibited stable cycling stability for over 1200 hours at a specific areal capacity density; however, the non-in-situ polymerized gel electrolyte of Comparative Example 1 showed short-circuiting after 40 hours of cycling, indicating poor cycling stability. -1 The battery was damaged after 3,000 cycles at the specified current density, while the gel electrolyte constructed in situ in Examples 1-3 had a cycle life of up to 10,000 cycles, indicating that the gel electrolyte constructed in situ can effectively enhance the cycle stability of the battery.

[0027] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for in-situ self-initiated construction of a gel electrolyte on an electrode surface, characterized in that, The method includes the following steps: (1) Dissolve zinc salt in water to obtain a liquid electrolyte; (2) Mix the gel monomer, initiator, crosslinking agent and liquid electrolyte to obtain a precursor solution; (3) The precursor solution is poured onto the surface of the negative electrode of the battery, and the positive electrode of the battery is covered onto the precursor solution and left to stand, so as to realize the in-situ construction of gel electrolyte on the electrode surface.

2. The method for in-situ self-initiated construction of gel electrolyte on electrode surface according to claim 1, characterized in that, In step (1), the zinc salt is selected from one of zinc sulfate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate, zinc perchlorate, and zinc chloride.

3. The method for in-situ self-initiated construction of gel electrolyte on electrode surface according to claim 1, characterized in that, In step (1), the concentration of the liquid electrolyte is 240-1200 g / L.

4. The method for in-situ self-initiated construction of gel electrolyte on electrode surface according to claim 1, characterized in that, In step (2), the gel monomer is one of acrylamide, acrylic acid, and acrylamide derivatives; The crosslinking agent is one of N,N-dimethylbisacrylamide, N,N'-(1,2-dihydroxyethylidene)bisacrylamide, and N,N'-bisacryloylcysteine; The initiator is one of potassium persulfate, ammonium persulfate, or 4-(2-hydroxy-3-phenylpropenyl)phenyl ketone.

5. The method for in-situ self-initiated construction of gel electrolyte on electrode surface according to claim 1, characterized in that, In step (2), the mass ratio of the gel monomer, crosslinking agent, initiator and liquid electrolyte is 10~50:0.1~0.5:1~5:100~500.

6. The method for in-situ self-initiated construction of gel electrolyte on electrode surface according to claim 1, characterized in that, In step (3), the amount of precursor solution poured is 50-150 μL / cm³. -2 ; The settling time is 1-24 hours.

7. A gel electrolyte obtained by the method of in-situ self-initiated construction of a gel electrolyte on the electrode surface according to any one of claims 1-6.

8. The application of the gel electrolyte of claim 7 in an aqueous zinc metal battery.

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