Disaccharide eutectic gel electrolyte and preparation method and application thereof

Abstract

The invention relates to the field of zinc ion batteries, in particular to a disaccharide eutectic gel electrolyte and a preparation method and application thereof. The preparation method of the disaccharide eutectic gel electrolyte comprises the following steps: firstly, adding disaccharide, choline compounds and zinc sulfate into deionized water, heating and uniformly stirring, then adding a polyacrylamide monomer as well as a thermal initiator and a cross-linking agent which are adaptive to a polymerization reaction with the monomer, and carrying out thermal initiation to form the disaccharide eutectic gel electrolyte. According to the invention, two additives, namely disaccharide and choline, are ingeniously introduced into the traditional gel electrolyte, and the two additives can form the stable disaccharide eutectic gel electrolyte together in the heating and stirring process. According to the innovative strategy, a polyacrylamide hydrogen bond network is enhanced, the cycle performance of the gel electrolyte battery is greatly improved, the configuration entropy of the system is increased due to introduction of the multi-component additive, the problem that an existing gel zinc battery is low in cycle performance is solved, and application of the gel zinc battery in a harsh temperature environment becomes possible.

Description

Technical Field

[0001] The present invention relates to the field of zinc ion batteries, and in particular to a disaccharide eutectic gel electrolyte and a preparation method and application thereof. Background Art

[0002] Aqueous zinc-ion batteries, due to their high compatibility with aqueous electrolytes and the low cost of zinc metal materials, have shown significant potential for application in energy storage technology. However, in their practical application, zinc-ion batteries still face a series of challenges, including zinc dendrite growth through the separator, hydrogen evolution reaction, and self-corrosion, which severely restrict their promotion and application. Compared with traditional aqueous liquid electrolytes, gel electrolytes offer unique performance advantages. Specifically, hydrogels, with their inherent modulus, can effectively mechanically inhibit zinc dendrite formation, significantly reducing the risk of dendrite penetration through the separator. Furthermore, the functional groups in the three-dimensional network structure of the gel electrolyte can interact with zinc ions, optimizing their solvation structure, chemically inducing uniform zinc deposition, and further improving electrochemical cycling stability. In summary, gel zinc-ion batteries effectively inhibit zinc dendrite growth through a triple chemical and mechanical mechanism, opening up the possibility of designing low-cost membrane materials and providing a viable alternative to the high cost of glass fiber separators in traditional liquid electrolytes, significantly promoting the commercialization of aqueous zinc-ion batteries.

[0003] However, gel electrolytes still face some key issues that need to be addressed in practical applications. On the one hand, the cycling performance of gel zinc-ion batteries needs to be improved; on the other hand, the water in the gel electrolyte is easily lost, affecting its long-term stability. To address these challenges, researchers are actively exploring strategies to add specific additives to gel electrolytes in order to improve their electrochemical performance. However, the stability of gel electrolytes in extreme environments remains a serious problem: under high temperature conditions, the gel is prone to dehydration and hardening, resulting in performance degradation; while at low temperatures, the gel may coagulate and become inactive, seriously affecting battery performance. These problems severely limit the practical application prospects of gel zinc-ion batteries. Therefore, while promoting the continuous development of gel electrolyte technology, it is necessary to deeply explore and solve the above key issues to ensure that gel zinc-ion batteries can exert their unique advantages in more application scenarios. Summary of the Invention

[0004] Based on this, the present invention provides a method for significantly improving the electrochemical performance of a gel electrolyte by introducing a low-cost additive into the gel electrolyte, enabling the gel electrolyte to have excellent performance at high and low temperatures that traditional gel electrolytes do not have, thereby solving the problems of complex preparation process and poor electrochemical performance under extreme conditions when existing gel electrolytes are used in zinc-ion batteries.

[0005] To achieve the above objectives, the present invention provides a method for preparing a disaccharide eutectic gel electrolyte. First, a disaccharide, a choline compound, and zinc sulfate are added to deionized water, heated and stirred evenly, and then a polyacrylamide monomer and a thermal initiator and a cross-linking agent compatible with the polymerization reaction of the polyacrylamide monomer are added to form a disaccharide eutectic gel electrolyte through thermal initiation.

[0006] As a further preferred technical solution of the present invention, the concentration of zinc sulfate added to deionized water is 1 to 3 M, such as 1 M, 1.5 M, 2 M, 2.5 M or 3 M.

[0007] As a further preferred technical solution of the present invention, the disaccharide is added to deionized water at a concentration of 0.01-0.1 mol / L, such as 0.01 mol / L, 0.02 mol / L, 0.05 mol / L, 0.07 mol / L or 0.1 mol / L.

[0008] As a further preferred technical solution of the present invention, the choline compound is added to deionized water at a concentration of 0.01-0.1 mol / L, such as 0.01 mol / L, 0.02 mol / L, 0.05 mol / L, 0.07 mol / L or 0.1 mol / L.

[0009] More preferably, the molar ratio of the choline compound to the disaccharide is 1:1 to 1:2.

[0010] As a further preferred technical solution of the present invention, the disaccharide, choline compound, and zinc sulfate are added to deionized water and heated and stirred at a temperature of 50-90°C for 30 minutes to 2 hours. If the heating and stirring time is too long, it will cause agglomeration after the subsequent addition of polyacrylamide monomer, thermal initiator, and cross-linking agent, and no gel will form. Adjusting the heating and stirring temperature will change the reaction activity accordingly, thereby reducing the heating and stirring accordingly. The specific temperature can be adjusted according to actual needs. It is further preferred to heat and stir at 60°C for 2 hours.

[0011] As a further preferred technical solution of the present invention, the thermal initiator is ammonium persulfate, and the cross-linking agent is N,N-methylenebisacrylamide.

[0012] As a further preferred technical solution of the present invention, the disaccharide is at least one of lactose, sucrose, maltose, and trehalose; and / or the choline compound is at least one of choline chloride, choline bromide, and choline iodide.

[0013] According to another aspect of the present invention, the present invention also provides a disaccharide eutectic gel electrolyte.

[0014] According to another aspect of the present invention, the present invention also provides a use of a disaccharide eutectic gel electrolyte as an electrolyte in an aqueous zinc ion battery.

[0015] The present invention cleverly introduces two additives - disaccharides and choline. Disaccharides have excellent stability and protective effects, and can maintain the structural integrity of the electrolyte at extreme temperatures. Choline is a quaternary ammonium salt compound with high ionic conductivity and thermal stability. It can form a hydrogen bond network with disaccharides, enhancing the mechanical strength and electrochemical stability of the electrolyte. During the heating and stirring process, the hydroxyl group (-OH) of the disaccharide acts as a hydrogen bond donor, and the chloride ion (Cl-) or hydroxyl group (-OH) of the choline and the sulfate ion (SO4) of the zinc sulfate 2- ) as a hydrogen bond acceptor. Disaccharides and choline interact through hydrogen bonds to form a stable disaccharide eutectic gel electrolyte. Its hydrogen bond network inhibits the crystallization process, so that the electrolyte does not condense at low temperatures; at the same time, the strong hydrogen bond interaction makes the system less likely to decompose at high temperatures. In addition, the ions provided by choline (such as Cl - 、Zn 2+ and SO4 2- ) migrate in the hydrogen bond network, improving the conductivity of the electrolyte. In addition, the introduction of multi-component additives such as disaccharides and choline additives The presence of multiple components increases the configurational entropy of the system, inhibits crystallization and phase separation, so that the disaccharide eutectic gel maintains a stable gel state at low temperatures; and the strong interactions between the various components in the high-entropy electrolyte (such as hydrogen bonds, ion-dipole interactions, etc.) enhance the thermal stability of the system, making it less likely to decompose at high temperatures, thereby improving the high-temperature cycle stability of the battery. Moreover, compared with monosaccharides such as glucose and fructose, disaccharides have a larger molecular weight and a higher proportion of hydroxyl groups, which can provide more active sites in the gel network, increase the number of pores in the gel, and allow more zinc ion transmission, which also greatly improves the electrochemical performance of the gel. In summary, the introduction of disaccharide and choline additives forms a stable disaccharide eutectic gel electrolyte, which strengthens the original three-dimensional hydrogen bond network of the polyacrylamide gel, inhibits crystallization and side reactions, and can tightly bind to the amide groups of the acrylamide monomer, balancing the charge distribution of the polyacrylamide gel, changing the bound state of water molecules, making the electric field more evenly distributed in the gel electrolyte, and giving the gel network stronger zinc ion migration ability and more excellent water retention capacity, thereby significantly improving the electrochemical performance and water retention of the gel. This makes the gel electrolyte exhibit excellent electrochemical performance in both high and low temperature environments and has a wide temperature range stability.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0017] 1) The preparation method of the present invention greatly improves the cycle performance of the battery by adding an ionic ligand additive, and the added additive is low in price and easy to industrialize.

[0018] 2) The present invention introduces additives to enable the gel electrolyte to have excellent electrochemical properties at low and high temperatures.

[0019] 3) The gel electrolyte of the present invention is applied in zinc ion batteries, so that the zinc ion batteries have excellent cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 The zinc-zinc symmetrical battery assembled based on the gel electrolyte in Example 1 is 1 mA cm at room temperature. -2 , 1mAhcm -2 Cyclic stability curves at current densities of ;

[0022] Figure 2 The zinc-copper half-cell assembled based on the gel electrolyte in Example 1 is 1 mA cm at room temperature. -2 , 1mAhcm -2 Coulomb efficiency stability curve at current density;

[0023] Figure 3 The full battery assembled based on the gel electrolyte in Example 1 was tested at different current densities of 0.5Ag at room temperature. -1 Rate curve under current density;

[0024] Figure 4 This is a photo of the gel electrolyte in Example 2 after being placed in a low-temperature environment for 12 hours;

[0025] Figure 5 The full battery assembled based on the gel electrolyte in Example 1 was heated at low temperature 0.5Ag -1 Cycling stability curves at current densities of .

[0026] Figure 6 The zinc-zinc symmetrical battery assembled based on the gel electrolyte in Example 1 was 1 mA cm -2 , 1mAhcm -2 Cyclic stability curves at current densities of ;

[0027] Figure 7 This is a photograph of the gel electrolyte prepared in Example 1 of the present invention after being placed in a high temperature environment for 12 hours;

[0028] Figure 8The electrochemical performance of the zinc-zinc symmetrical battery assembled based on the gel electrolyte in Example 1 at high temperature;

[0029] Figure 9 The electrochemical performance of the zinc-zinc symmetrical battery assembled based on the gel electrolyte in Example 2 at low temperature.

[0030] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0031] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0032] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods described, unless otherwise specified, are conventional methods.

[0033] The present invention provides a method for preparing a disaccharide eutectic gel electrolyte, which is a method for improving the electrochemical performance of a gel electrolyte by using dual additives. The preparation method is simple and efficient. Specifically, the method comprises the following steps: adding a disaccharide (including but not limited to one or more of lactose, sucrose, maltose, and trehalose) and a choline compound (including but not limited to one or more of choline chloride, choline bromide, and choline iodide) to a ZnSO4 solution; heating and stirring the mixture; then adding an acrylamide monomer, a thermal initiator (APS), and a crosslinking agent (MBAA) to the mixture to form an electrolyte precursor; and gradually agglomerating the electrolyte precursor through thermal initiation to form a gel electrolyte.

[0034] In the technical solution of the present invention, acrylamide (AM), ammonium persulfate (APS), N,N-methylenebisacrylamide (MBAA), disaccharides and choline compounds are all commonly used chemical materials, which makes this method have the advantages of wide and easy access to raw materials and low cost. The introduction of a low-cost additive into the gel electrolyte enables it to have excellent performance at high and low temperatures that traditional electrolytes do not have.

[0035] The electrochemical performance comparison test methods and corresponding device compositions in the following examples and comparative examples are as follows:

[0036] 1. Symmetrical battery:

[0037] Use 12mm diameter zinc sheets as the positive and negative electrodes of the battery

[0038] 2. Half-cell:

[0039] The positive electrode uses a 10mm copper sheet and the negative electrode uses a 12mm zinc sheet.

[0040] 3. Full battery:

[0041] The positive electrode uses commercial vanadium pentoxide as the positive electrode, and the ratio of vanadium pentoxide: super P: polyvinylidene fluoride (PVDF) is coated on steel foil and cut into 10mm diameter discs as the positive electrode. The negative electrode uses a 12mm zinc sheet, and the active material loading is about 1.2mg / cm 2

[0042] The obtained gel electrolyte sample was cut into discs with a diameter of 16 mm and a thickness of 1 mm as the electrolyte of the battery. No additional electrolyte was added, and CR2032 button batteries were assembled for testing.

[0043] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the technical solution of the present invention is further described in detail below through specific embodiments.

[0044] Comparative Example 1: Preparation of traditional blank gel electrolyte.

[0045] 5 g of acrylamide (AM) monomer was added to 10 mL of 2 M ZnSO4 aqueous solution and stirred evenly. Then, 25 mg (5 wt% relative to AM) of initiator APS and 10 mg (2 wt% relative to AM) of cross-linker MBAA were added. After stirring evenly, the mixture was placed in an oven at 60 ° C for 20 minutes to finally obtain a blank gel electrolyte without additives.

[0046] Comparative Example 2: Preparation of monosaccharide eutectic gel electrolyte.

[0047] 0.5 mmol glucose (concentration 0.05 mol / L) and 0.5 mmol choline chloride (concentration 0.05 mol / L) were added to 10 mL 2M ZnSO4 aqueous solution, respectively, and heated with stirring at 60°C for 2 h. After the solution cooled, 5 g acrylamide (AM) monomer was added, followed by 25 mg (5 wt% relative to AM) initiator APS and 10 mg (2 wt% relative to AM) MBAA as a cross-linker. After stirring evenly, the mixture was placed in an oven at 60°C for 20 min to obtain a monosaccharide eutectic electrolyte.

[0048] Example 1: Preparation of disaccharide eutectic gel electrolyte.

[0049] 0.5 mmol sucrose (concentration 0.05 mol / L) and 0.5 mmol choline chloride (concentration 0.05 mol / L) were added to 10 ml 2M ZnSO4 aqueous solution, mixed evenly, and heated with stirring at 60 ° C for 2 h. After the solution cooled, 5 g acrylamide (AM) monomer was added, and then 25 mg (5 wt% relative to AM) cross-linker APS and 10 mg (2 wt% relative to AM) MBAA initiator were added. After stirring evenly, the mixture was placed in a 60 ° C oven for 20 min to obtain a disaccharide eutectic gel electrolyte.

[0050] Example 2: Preparation of disaccharide eutectic gel electrolyte.

[0051] 0.5 mmol maltose (concentration 0.05 mol / L) and 1 mmol choline bromide (concentration 0.1 mol / L) were added to 10 ml of 2M ZnSO4 aqueous solution, mixed evenly, and heated with stirring at 60°C for 30 min. After the solution cooled, 5 g acrylamide (AM) monomer was added, followed by 25 mg (5 wt% to AM) crosslinker APS and 10 mg (2 wt% to AM) MBAA initiator. After stirring evenly, the mixture was placed in a 60°C oven for 20 min to obtain a gel.

[0052] like Figure 1 As shown, the zinc-zinc batteries assembled with the gel electrolytes obtained in Comparative Example 1, Comparative Example 2 and Example 1 were tested at 25°C and 1 mA cm -2 , 1mAh cm -2 The cycling stability curve at a current density of 1.5 Å is shown. It can be seen that at this current density, after cycling for 1800 h, the gel electrolyte of Example 1 still exhibits excellent cycling stability and long cycle life, while the blank gel electrolyte of Comparative Example 1 and the monosaccharide eutectic gel electrolyte of Comparative Example 2 exhibit short circuits after cycling for 300 h and 850 h, respectively.

[0053] Figure 2 The zinc-copper half-cell assembled based on the gel electrolyte of the two comparative examples and Example 1 was -2 , 1mAhcm -2 The coulombic efficiency curve under the current density of , the test results show that the half-cell assembled with disaccharide eutectic gel electrolyte can stably cycle 700 cycles, and the average coulombic efficiency is maintained at 99.18%, which is significantly better than the blank gel electrolyte (80 cycles) and the monosaccharide eutectic electrolyte (360 cycles).

[0054] Figure 3 The rate curves of the full battery assembled based on the gel electrolytes of the two comparative examples and Example 1 at 25°C show that the discharge capacity of the disaccharide eutectic gel electrolyte at different current densities is obviously better than that of the blank gel electrolyte and the monosaccharide eutectic gel electrolyte.

[0055] Figure 4 The following are photos of the gel electrolytes obtained in Comparative Example 1 and Example 1 at low temperatures. Comparison of the gel electrolytes obtained in Example 1 and Comparative Example 1 after being placed at -20°C for 12 hours reveals that the conventional gel electrolyte solidifies and turns white at low temperatures, while the eutectic electrolyte remains transparent. Figure 5 The full battery assembled based on three gel electrolytes at 0.5Ag -1 It can also be seen from the long cycle curve below that the blank gel electrolyte shows a huge change in capacity in a short period of time, indicating that it freezes at this temperature, while the eutectic gel electrolyte does not freeze, and the disaccharide eutectic gel electrolyte is significantly better than the monosaccharide eutectic gel electrolyte.

[0056] Figure 6 The zinc symmetric battery assembled based on the gel electrolyte of Example 1 was heated at -20°C and 1 mA cm -2 , 1mAh cm -2 The test results show that at low temperature, compared with the blank gel electrolyte that short-circuits after 300h of cycling, the disaccharide eutectic gel electrolyte can stably cycle for 1200h (better than the monosaccharide eutectic gel electrolyte for 700h).

[0057] Figure 7 The blank gel electrolyte of comparative example 1 was compared with the disaccharide eutectic gel electrolyte of example 1 after being placed in a 50°C oven for 12 hours. It can be clearly observed that the blank gel electrolyte shrank significantly and its volume became smaller, while the disaccharide eutectic gel electrolyte had almost no change, indicating its excellent stability at high temperature, which is consistent with the Figure 8 Symmetrical cell at 50℃, 1mAcm -2 , 1mAh cm -2 The test results show that at high temperature, compared with the short circuit after 800h of traditional gel electrolyte, the gel electrolyte with additives can be stably cycled for 1500h.

[0058] Figure 9 The figure shows the performance comparison of zinc symmetric batteries assembled based on the gel electrolytes of the two comparative examples and Example 2 at low temperature. Compared with the blank gel electrolyte that quickly freezes and the monosaccharide eutectic gel electrolyte that short-circuits after 700 hours of cycling, the disaccharide eutectic gel electrolyte can stably cycle for more than 1300 hours. This shows that the cycling performance of the disaccharide eutectic gel electrolyte is better than that of the monosaccharide eutectic gel electrolyte.

[0059] In order to further demonstrate the beneficial technical effects of the present invention, based on the preparation method of Example 1, a eutectic gel electrolyte was prepared according to the eutectic solvent formula shown in Table 1 and a symmetrical battery was assembled.

[0060] Table 1 summarizes the comparative data of cycle time of symmetrical batteries assembled based on different sugars and cholines.

[0061] Table 1

[0062]

[0063] From the data analysis in Table 1, it can be seen that the disaccharide eutectic gel electrolyte is significantly better than the monosaccharide eutectic gel electrolyte in improving the electrochemical stability of the battery.

[0064] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a disaccharide eutectic gel electrolyte, characterized in that: First, disaccharide, choline compound and zinc sulfate are added to deionized water, heated and stirred evenly, and then polyacrylamide monomer and thermal initiator and cross-linking agent compatible with polyacrylamide monomer are added to form disaccharide eutectic gel electrolyte through thermal initiation.

2. The method for preparing the disaccharide eutectic gel electrolyte according to claim 1, characterized in that: The zinc sulfate is added to deionized water at a concentration of 1 to 3 M (mol / L).

3. The method for preparing the disaccharide eutectic gel electrolyte according to claim 1, characterized in that: The disaccharide is added to deionized water at a concentration of 0.01-0.1 mol / L.

4. The method for preparing the disaccharide eutectic gel electrolyte according to claim 1, characterized in that: The choline compound is added to deionized water at a concentration of 0.01-0.1 mol / L.

5. The method for preparing the disaccharide eutectic gel electrolyte according to claim 1, characterized in that: The disaccharide, choline compound and zinc sulfate are added into deionized water, heated and stirred at a temperature of 50-90° C. for 30 min-2 h.

6. The method for preparing the disaccharide eutectic gel electrolyte according to claim 1, characterized in that: The thermal initiator is ammonium persulfate, and the cross-linking agent is N,N-methylenebisacrylamide.

7. The method for preparing a disaccharide eutectic gel electrolyte according to any one of claims 1 to 6, characterized in that: The disaccharide is at least one of lactose, sucrose, maltose and trehalose, and the choline compound is at least one of choline chloride, choline bromide and choline iodide.

8. A disaccharide eutectic gel electrolyte, characterized in that: The method according to any one of claims 1 to 7 is used for preparation.

9. Use of the disaccharide eutectic gel electrolyte according to claim 8 as an electrolyte in an aqueous zinc ion battery.

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