A hydrogel electrolyte and its preparation and use in zinc-ion batteries

Abstract

The present application relates to the technical field of zinc ion hydrogel battery, in particular to a hydrogel electrolyte, which is a hydrogel formed by cross-linking polysaccharide, composite sugar of disaccharide and zinc ion; the polysaccharide is a polysaccharide component capable of cross-linking with zinc ion; the weight ratio of the polysaccharide and the disaccharide is 1:0.5-3.5. The present application also comprises a preparation method and application of the hydrogel electrolyte. The hydrogel electrolyte has excellent low-temperature resistance, and when used as the hydrogel electrolyte of zinc ion battery, can improve the electrochemical performance, especially the low-temperature electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of aqueous battery materials, and more specifically to the field of hydrogel electrolyte technology for zinc-ion hydrogel batteries. Background Technology

[0002] With its advantages of low cost, high safety, environmental friendliness, and biocompatibility, rechargeable zinc-ion batteries using mild zinc salt aqueous solutions as electrolytes have become a rising star in the field of electrochemical energy storage in recent years. It holds great promise for large-scale energy storage. However, traditional aqueous electrolyte systems have revealed some problems that urgently need to be addressed, such as the excessive growth of zinc dendrites caused by poor matching between the separator and the zinc anode, and severe side reactions and hydrogen evolution corrosion caused by the high activity of water molecules. Furthermore, the tendency of aqueous electrolytes to freeze easily limits the application of zinc-ion batteries at low temperatures.

[0003] On the other hand, in the era of big data, the demand for wearable electronic devices is constantly growing, which requires energy storage devices to achieve high safety and high flexibility. Compared with electrochemical energy storage systems such as lead-acid batteries, lithium-ion batteries, and flow batteries, zinc-ion batteries are more suitable for flexible energy storage, but they still have the risk of electrolyte leakage. Hydrogels can retain a large amount of water without leakage and avoid direct contact between water molecules and the zinc anode, thereby mitigating hydrogen evolution corrosion and side reaction problems on the anode side. If the hydrogel has high adhesion and strength, it can also effectively inhibit the growth of zinc dendrites. In addition, through composite methods, hydrogels can be endowed with special functions such as excellent flexibility, dehydration resistance, and freeze resistance. Therefore, hydrogel electrolytes are expected to replace liquid electrolytes to realize the large-scale, miniaturized, and wide-temperature-range application of zinc-ion batteries.

[0004] Currently, various polymer-based hydrogels have been reported as electrolyte materials for zinc-ion batteries, involving matrix materials such as polyacrylamide, polyvinyl alcohol, starch, and guar gum. Unfortunately, these hydrogel electrolytes cannot simultaneously meet the requirements of low cost, high ionic conductivity, high mechanical properties, and low-temperature resistance, which hinders their industrialization.

[0005] Furthermore, to address the challenges faced by polymer-based hydrogels, existing technologies typically employ chemical covalent crosslinking or the construction of multiple networks and the introduction of organic liquid components to further improve the mechanical properties and low-temperature resistance of the hydrogel electrolyte. Achieving covalent crosslinking generally requires the use of crosslinking agents, which inevitably leads to agent residue issues. Constructing multiple networks also presents the aforementioned problems, and the process for preparing hydrogels using this strategy is more complex compared to single-matrix hydrogels. While introducing organic liquid components can effectively suppress water freezing within the hydrogel network, it also presents challenges such as increased cost, a significant decrease in ionic conductivity, and safety concerns. Summary of the Invention

[0006] To address the unsatisfactory mechanical, antifreeze, and electrochemical properties of existing simple glycosyl hydrogel electrolytes (referring to hydrogel electrolytes without conventional antifreeze agents or chemical crosslinking agents), the primary objective of this invention is to provide a hydrogel electrolyte that improves its mechanical properties, low-temperature resistance, and electrochemical properties.

[0007] The second objective of this invention is to provide a method for preparing the hydrogel electrolyte and its application in zinc-ion hydrogel batteries.

[0008] A third objective of this invention is to provide an aqueous hydrogel-type zinc-ion battery comprising the aforementioned hydrogel electrolyte.

[0009] The technical solution of this invention is as follows:

[0010] Hydrogel electrolytes are hydrogels formed by cross-linking of complex sugars containing polysaccharides and disaccharides with zinc ions;

[0011] The polysaccharide mentioned is a polysaccharide component capable of cross-linking with zinc ions;

[0012] The weight ratio of the polysaccharide to the disaccharide is 1:0.5 to 3.5.

[0013] To address the issues of unsatisfactory mechanical stability and freeze resistance of simple glycosyl hydrogel electrolytes, this invention demonstrates an innovative method of crosslinking polysaccharides with zinc ions using disaccharides. This repairs crosslinking network defects, improves zinc ion conduction pathways and efficiency, and enhances the disorder of water molecules within the hydrogel at low temperatures, thereby improving low-temperature performance. When this hydrogel electrolyte is used in zinc-ion batteries, its low-temperature electrochemical performance is improved.

[0014] In this invention, the polysaccharide is at least one selected from chitosan and its salts, alginate and its salts, pectin, and carboxymethyl cellulose and its salts. The salts of the polysaccharides can be anionic salts of polysaccharide cations (such as chitosan), for example, at least one selected from hydrochloride, nitrate, sulfate, and sulfonate. Alternatively, the salts of the polysaccharides can also be cationic salts of polysaccharide anions (such as alginate and carboxymethyl cellulose), for example, at least one selected from ammonium, sodium, and potassium salts. Considering processing costs and synergistic processing effects, the polysaccharide is further preferably at least one selected from alginate, sodium alginate, potassium alginate, and ammonium alginate.

[0015] In this invention, the disaccharide is at least one selected from maltose, lactose, sucrose, and trehalose; more preferably, it can be at least one selected from maltose and lactose; even more preferably, it is a mixed disaccharide of maltose and lactose in a mass ratio of 1-2:1-2. This invention has found that the preferred combination of disaccharide and polysaccharide can further synergistically improve the network cross-linked with zinc ions and induce the disordered distribution of water at low temperatures, thus contributing to further synergistic improvement of the performance of the obtained hydrogel electrolyte.

[0016] In this invention, the percentage of zinc in the hydrogel electrolyte can be determined by conventional testing methods, such as EDS and ICP, and its range is, for example, 5% to 20%.

[0017] The present invention also provides a method for preparing the hydrogel electrolyte, wherein an aqueous solution of raw materials containing polysaccharides, disaccharides and zinc ion sources is crosslinked to obtain the hydrogel electrolyte.

[0018] In this invention, the raw material aqueous solution can be obtained based on known mixing methods. For example, a sugar aqueous solution containing dissolved polysaccharides and disaccharides can be mixed with a zinc aqueous solution containing a zinc ion source to obtain the raw material aqueous solution. In this invention, the sugar aqueous solution can be obtained based on known methods. For example, sugar and water can be mixed using conventional stirring to form the sugar aqueous solution, and if necessary, the dissolution of polysaccharides and disaccharides can be promoted by conventional heating and / or ultrasound-assisted methods.

[0019] In this invention, the concentration of polysaccharide in the sugar solution is 1-10 g:100 mL, preferably 3-7 g:100 mL, and further preferably 4.5-5.5 g:100 mL. This invention has found that at the preferred concentration, it can further improve the hydrogel network formed by cross-linking with zinc ions, which helps to further improve its low-temperature performance.

[0020] Preferably, the weight ratio of polysaccharide to disaccharide in the sugar solution is 1:0.8–2.5; more preferably, it is 1:1–1.5. At the preferred polysaccharide concentration and polysaccharide-disaccharide ratio, the hydrogel's structural repair and low-temperature zinc ion conductivity can be synergistically improved.

[0021] In this invention, the zinc aqueous solution is an aqueous solution containing dissolved zinc ions, specifically an aqueous solution of at least one of zinc ion sulfate, perchlorate, chloride, and trifluoromethane sulfonate. In this invention, the concentration of zinc ions in the zinc aqueous solution can be adjusted as needed, for example, it can be 0.5–3 M, more preferably 1.5–2.5 M, and considering both effectiveness and cost, it is further preferably 1.8–2.4 M.

[0022] In this invention, the volume ratio of the sugar solution and the zinc solution can be adjusted as needed to ensure that they come into contact and can crosslink. For example, the volume ratio of the zinc solution to the sugar solution is greater than or equal to 0.5; preferably greater than or equal to 1; and considering the processing cost, it can be further 1.5 to 3:1.

[0023] In this invention, the cross-linking refers to the cross-linking between polysaccharides and zinc ions. In this invention, depending on the preparation requirements, the sugar solution can be pre-emptively de-aired and leveled in a mold, and then mixed with a zinc ion solution for static cross-linking.

[0024] In this invention, there are no special requirements for the crosslinking time, as long as gelation is formed. For example, the crosslinking reaction time is more than 0.5 hours. Considering the processing efficiency and effect, it can be further 1 to 3 hours. Considering the effect and processing efficiency, it can be further 1.5 to 2.5 hours.

[0025] In this invention, there are no special requirements for the temperature of the crosslinking reaction process; for example, it can be 10–40°C, or even room temperature.

[0026] In this invention, after the crosslinking reaction, the obtained hydrogel can be washed with water as needed to obtain the hydrogel electrolyte.

[0027] The present invention also provides an application of the aforementioned hydrogel electrolyte, using it as an electrolyte in the preparation of a hydrogel-type zinc-ion battery. For example, it is placed between the positive and negative electrodes of a zinc-ion battery to form a cell for a hydrogel-type zinc-ion battery, and then the hydrogel-type zinc-ion battery is obtained based on conventional packaging methods.

[0028] In this invention, thanks to the combination of the hydrogel electrolyte components, the conductivity of zinc ions can be synergistically improved, which is beneficial to improving its mechanical properties and the electrochemical performance of zinc-ion batteries, especially at low temperatures.

[0029] In this invention, the hydrogel electrolyte described herein can be prepared into the desired aqueous zinc-ion battery based on existing conventional methods and theories.

[0030] The present invention also provides an aqueous hydrogel zinc-ion battery, comprising a cell comprising a positive electrode, a hydrogel electrolyte, and a negative electrode sequentially bonded together, wherein the hydrogel electrolyte is the aforementioned hydrogel electrolyte.

[0031] The aqueous hydrogel zinc-ion battery of the present invention, except for the hydrogel electrolyte described in the present invention, may use materials, battery structures and components that are known in the industry.

[0032] For example, in this invention, the positive electrode can be at least one of polyaniline, manganese dioxide, and vanadium pentoxide;

[0033] For example, the negative electrode is at least one of zinc foil and zinc powder;

[0034] The aqueous hydrogel zinc-ion battery further includes a battery casing that houses the battery cell.

[0035] Beneficial effects:

[0036] The hydrogel electrolyte described in this invention not only possesses excellent mechanical properties but also achieves high ionic conductivity and exhibits outstanding low-temperature resistance.

[0037] The raw materials of this invention are low in cost, and the process is simple to operate and easy to scale up for production. Attached Figure Description

[0038] Figure 1 (a) A digital photograph of the hydrogel obtained in Example 1 and (b) A SEM image of the hydrogel after freeze-drying;

[0039] Figure 2 The tensile stress-strain curve of the hydrogel electrolyte obtained in Example 1 is shown.

[0040] Figure 3 The Nyquist plot of the stainless steel / / hydrogel electrolyte / / stainless steel battery obtained in Example 1 at 20°C;

[0041] Figure 4 The Nyquist plot of the stainless steel / / hydrogel electrolyte / / stainless steel battery obtained in Example 1 at 0°C;

[0042] Figure 5 The Nyquist plot of the stainless steel / / hydrogel electrolyte / / stainless steel battery obtained in Example 1 at -20°C;

[0043] Figure 6 The cycle performance of the zinc-ion battery obtained in Example 1 at 20°C and 0.2 A / g current density is shown.

[0044] Figure 7 The cycle performance of the zinc-ion battery obtained in Example 1 at 0°C and 0.2 A / g current density is shown.

[0045] Figure 8 The cycle performance of the zinc-ion battery obtained in Example 1 at -20°C and 0.2 A / g current density is shown.

[0046] Figure 9 (a) A digital photograph of the hydrogel obtained in Comparative Example 1 and (b) a SEM image of the freeze-dried hydrogel. Detailed Implementation

[0047] To further understand the content of this invention, it will be described in detail with reference to embodiments, comparative examples and accompanying drawings.

[0048] In a typical embodiment of the present invention, the polysaccharide, taking sodium alginate as an example, is prepared using the following typical steps for a high-strength antifreeze hydrogel electrolyte for zinc-ion batteries:

[0049] Step (1): Add sodium alginate and disaccharide simultaneously to deionized water and stir vigorously until they are completely dissolved to obtain a sugar solution; the disaccharide is any one or more combinations of maltose, lactose, sucrose, and trehalose. In the sugar solution, the concentration of sodium alginate is, for example, 3-7 g: 100 mL; the weight ratio of polysaccharide to disaccharide is 1:0.8-2.5; more preferably 1:1-1.5.

[0050] Step (2): As needed, sonicate the sugar solution obtained in step (1) and let it stand for a while to remove air bubbles, then transfer it to a polytetrafluoroethylene mold and wait for the liquid surface to flow and flatten naturally.

[0051] Step (3): Immerse the mold in a 1.5-2.5M ZnSO4 aqueous solution (the volume ratio of sugar solution and zinc solution is 1:0.5-3) for crosslinking for a certain period of time, then demold and wash the surface with water to obtain the hydrogel electrolyte. The crosslinking time is 1-3 hours.

[0052] This invention uses zinc ions as crosslinking centers, crosslinking them with polysaccharides such as sodium alginate with the assistance of disaccharides. This allows for rapid and spontaneous coordination with zinc ions, forming a hydrogel with high strength, modulus, and ionic conductivity. In this invention, the introduction of disaccharides into the sodium alginate hydrogel matrix effectively repairs various defects in the hydrogel network, such as dangling chain and ring defects, through multiple hydrogen bonds between the disaccharides and the sodium alginate chains, thus improving the mechanical properties of the sodium alginate hydrogel. Furthermore, the introduction of small-molecule disaccharides can uniformly and strongly disrupt the ordered arrangement of water molecules at low temperatures, thereby endowing the hydrogel electrolyte with excellent antifreeze properties. In addition to these two points, maintaining low cost, minimal sacrifice in ionic conductivity, and safety and stability are also significant advantages of this composite hydrogel electrolyte.

[0053] In the following cases, unless otherwise stated, the temperature of the crosslinking process refers to room temperature (15-35°C).

[0054] Example 1

[0055] 5g of sodium alginate and 5g of disaccharide (maltose in this case) were simultaneously added to 100mL of deionized water and stirred vigorously until completely dissolved. The resulting solution was sonicated and allowed to stand for a while to remove air bubbles. Then, it was transferred to a polytetrafluoroethylene mold, and after the liquid surface had naturally flowed and smoothed, it was completely immersed in 200mL of 2M ZnSO4 aqueous solution for crosslinking for 2 hours. Finally, it was demolded and the surface was washed with water to obtain the hydrogel electrolyte. See product photos below. Figure 1 (a) SEM image after freeze-drying (see image below) Figure 1 (b)

[0056] The tensile stress-strain curve of the hydrogel electrolyte prepared in this embodiment is as follows: Figure 2 As shown, the fracture strength is 0.50 MPa, the elastic modulus is 2.00 MPa, and the elongation at break is 38.97%, demonstrating excellent mechanical properties.

[0057] The hydrogel electrolyte prepared in this embodiment was assembled with two stainless steel sheets to form a stainless steel / / hydrogel electrolyte / / stainless steel battery. Electrochemical impedance spectroscopy was performed, and the Nyquist plots obtained at 20℃, 0℃, and -20℃ are shown below. Figure 3 , Figure 4 and Figure 5 As shown, the hydrogel electrolyte obtained in this embodiment has ionic conductivity as high as 22.43, 17.12 and 12.03 mS / cm at 20℃, 0℃ and -20℃, respectively, indicating that the hydrogel electrolyte not only has very high ionic conductivity, but also excellent antifreeze properties.

[0058] Aniline was in-situ oxidatively polymerized onto carbon cloth and cut into 10mm diameter discs as the positive electrode. A zinc foil negative electrode (14mm) and a hydrogel electrolyte (20mm) prepared in this embodiment were used to assemble a CR2025 coin-type zinc-ion battery. The charge / discharge voltage range for battery cycle testing was 0.5–1.5V. Figure 6 , Figure 7 and Figure 8 The figures show the cycle performance of the zinc-ion battery obtained in this embodiment, tested at 20°C, 0°C, and -20°C with a current density of 0.2 A / g. At 20°C, 0°C, and -20°C, the initial discharge specific capacities of the obtained zinc-ion batteries were 218.2 mAh / g, 166.2 mAh / g, and 120.6 mAh / g, respectively, and the capacity retention rates after 250 cycles were 88.3%, 93.5%, and 87.0%, respectively. These test results demonstrate that the zinc-ion battery based on the hydrogel electrolyte prepared in this embodiment exhibits excellent electrochemical performance at both room temperature and low temperatures.

[0059] The above results demonstrate that the hydrogel electrolyte obtained in this embodiment possesses excellent mechanical properties, very high ionic conductivity, and excellent antifreeze properties.

[0060] Example 2

[0061] Compared with Example 1, the only difference is that lactose is used as the disaccharide, while all other operations and parameters are the same as in Example 1.

[0062] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 20.11 mS / cm and a tensile strength of 0.42 MPa at 20°C. The ionic conductivity at -20°C was 10.65 mS / cm.

[0063] Example 3

[0064] Compared with Example 1, the only difference is that the amount of maltose added is adjusted to 10g, and all other operations and parameters are the same as in Example 1.

[0065] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 10.71 mS / cm and a tensile strength of 0.31 MPa at 20°C. The ionic conductivity at -20°C was 4.46 mS / cm.

[0066] Example 4

[0067] Compared with Example 1, the only difference is that the amount of sodium alginate added is adjusted to 3g, and all other operations and parameters are the same as in Example 1.

[0068] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 13.55 mS / cm and a tensile strength of 0.24 MPa at 20°C. The ionic conductivity at -20°C was 5.93 mS / cm.

[0069] Example 5

[0070] Compared with Example 1, the only difference is that the crosslinking time is adjusted to 1 hour, while all other operations and parameters are the same as in Example 1.

[0071] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 11.81 mS / cm and a tensile strength of 0.28 MPa at 20°C. The ionic conductivity at -20°C was 6.64 mS / cm.

[0072] Example 6

[0073] Compared with Example 1, the only difference is that the disaccharide combination of 2.5g maltose + 2.5g lactose is used instead of 5g maltose. All other operations and parameters are the same as in Example 1.

[0074] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 23.03 mS / cm and a tensile strength of 0.52 MPa at 20°C. The ionic conductivity at -20°C was 13.32 mS / cm.

[0075] Compared with Examples 1 and 6, the combination of maltose and lactose unexpectedly achieves synergy and can further improve low-temperature performance.

[0076] Example 7

[0077] Compared with Example 1, the only difference is that pectin is used as the polysaccharide; all other operations and parameters are the same as in Example 1.

[0078] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 21.77 mS / cm and a tensile strength of 0.46 MPa at 20°C. The ionic conductivity at -20°C was 10.92 mS / cm.

[0079] Example 8

[0080] Compared with Example 1, the only difference is that the concentration of the ZnSO4 aqueous solution is adjusted to 1.5M, and all other operations and parameters are the same as in Example 1.

[0081] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 15.63 mS / cm and a tensile strength of 0.39 MPa at 20°C. The ionic conductivity at -20°C was 9.27 mS / cm.

[0082] Comparative Example 1

[0083] Compared to Example 1, the only difference is the absence of maltose; all other operations and parameters are the same as in Example 1. A photograph of the resulting hydrogel electrolyte can be found... Figure 9 (a) SEM image after freeze-drying (see image below) Figure 9 (b)

[0084] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 10.36 mS / cm and a tensile strength of 0.21 MPa at 20°C. The ionic conductivity at -20°C was 1.75 mS / cm.

[0085] Comparative Example 2

[0086] Compared with Example 1, the only difference is that maltose is missing, and the missing amount is supplemented by sodium alginate. That is, the amount of sodium alginate is adjusted to 10g. Other operations and parameters are the same as in Example 1.

[0087] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 7.14 mS / cm and a tensile strength of 0.47 MPa at 20°C. The ionic conductivity at -20°C was 0.93 mS / cm.

[0088] Compared with Comparative Examples 1 and 2, the lack of disaccharide assistance resulted in a significant decrease in low-temperature performance.

[0089] Comparative Example 3

[0090] Compared to Example 1, the only difference is the absence of sodium alginate, which was supplemented with maltose. All other operations and parameters are the same as in Example 1. This case failed to form a hydrogel, resulting in preparation failure.

[0091] Comparative Example 4

[0092] Compared with Example 1, the only difference is that fructose (monosaccharide) is used to replace the maltose by weight, while other operations and parameters are the same as in Example 1.

[0093] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 7.33 mS / cm and a tensile strength of 0.19 MPa at 20°C. The ionic conductivity at -20°C was 2.81 mS / cm.

[0094] Comparative Example 5

[0095] Compared with Example 1, the only difference is that the amount of maltose added is adjusted to 20g, and the other operations and parameters are the same as in Example 1.

[0096] The ionic conductivity and mechanical properties were measured according to the method in Example 1. The results were as follows: the hydrogel electrolyte obtained in this case had an ionic conductivity of 3.98 mS / cm and a tensile strength of 0.14 MPa at 20°C. The ionic conductivity at -20°C was 1.24 mS / cm.

Claims

1. A hydrogel electrolyte, characterized in that, It is a hydrogel formed by cross-linking of complex sugars containing polysaccharides and disaccharides with zinc ions; The weight ratio of the polysaccharide to the disaccharide is 1:0.8~2.5; The polysaccharide is at least one of alginic acid and its salts, pectin, carboxymethyl cellulose and its salts; The disaccharide is at least one of maltose, lactose, sucrose, and trehalose.

2. The hydrogel electrolyte as described in claim 1, characterized in that, The polysaccharide mentioned is sodium alginate.

3. The hydrogel electrolyte as described in claim 1, characterized in that, The disaccharide is a mixture of maltose and lactose in a mass ratio of 1~2:1~2.

4. A method for preparing the hydrogel electrolyte according to any one of claims 1 to 3, characterized in that, The hydrogel electrolyte is prepared by crosslinking an aqueous solution of raw materials containing polysaccharides, disaccharides, and a zinc ion source.

5. The method for preparing the hydrogel electrolyte as described in claim 4, characterized in that, The raw material aqueous solution is prepared by mixing a sugar aqueous solution containing polysaccharides and disaccharides with a zinc aqueous solution containing a zinc ion source.

6. The method for preparing the hydrogel electrolyte as described in claim 5, characterized in that, In the sugar solution, the concentration of polysaccharide is 1~10 g: 100 mL.

7. The method for preparing the hydrogel electrolyte as described in claim 6, characterized in that, In the sugar solution, the concentration of polysaccharide is 3~7 g: 100 mL.

8. The method for preparing the hydrogel electrolyte as described in claim 7, characterized in that, In the sugar solution, the concentration of polysaccharide is 4.5~5.5 g: 100 mL.

9. The method for preparing the hydrogel electrolyte as described in claim 5, characterized in that, In the sugar solution, the weight ratio of polysaccharide to disaccharide is 1:1 to 1.

5.

10. The method for preparing the hydrogel electrolyte as described in claim 5, characterized in that, Zinc aqueous solution is an aqueous solution containing dissolved zinc ions; In zinc aqueous solutions, the concentration of zinc ions is 0.5–3 M; The volume ratio of the zinc aqueous solution to the sugar aqueous solution is greater than or equal to 0.

5.

11. The method for preparing the hydrogel electrolyte as described in claim 10, characterized in that, The zinc aqueous solution is an aqueous solution of at least one of zinc ion sulfate, perchlorate, chloride, and trifluoromethane sulfonate. The volume ratio of zinc aqueous solution to sugar aqueous solution is 1.5~3:

1.

12. The method for preparing the hydrogel electrolyte according to any one of claims 4 to 11, characterized in that, The cross-linking reaction takes more than 0.5 hours.

13. The method for preparing the hydrogel electrolyte as described in claim 12, characterized in that, The cross-linking reaction takes 1 to 3 hours.

14. The method for preparing the hydrogel electrolyte as described in claim 12, characterized in that, After the cross-linking reaction, the obtained hydrogel is washed with water to obtain the hydrogel electrolyte.

15. The application of a hydrogel electrolyte according to any one of claims 1 to 3 or a hydrogel electrolyte prepared by the preparation method according to any one of claims 4 to 14, characterized in that, It was used as an electrolyte in the preparation of hydrogel-type zinc-ion batteries.

16. A water-based hydrogel zinc-ion battery, comprising a cell sequentially composited with a positive electrode, a hydrogel electrolyte, and a negative electrode, characterized in that, The hydrogel electrolyte is the hydrogel electrolyte according to any one of claims 1 to 3 or the hydrogel electrolyte prepared by the preparation method according to any one of claims 4 to 14.

17. The aqueous hydrogel zinc-ion battery as described in claim 16, characterized in that, The positive electrode is at least one of polyaniline, manganese dioxide, and vanadium pentoxide; The negative electrode is at least one of zinc foil and zinc powder; The aqueous hydrogel zinc-ion battery further includes a battery casing that houses the battery cell.

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