Wide-temperature-range and wide-voltage eutectic gel electrolyte for zinc ion battery as well as preparation method and application of wide-temperature-range and wide-voltage eutectic gel electrolyte

Abstract

The invention discloses a wide-temperature-range wide-voltage eutectic gel electrolyte for a zinc ion battery as well as a preparation method and application of the eutectic gel electrolyte, and belongs to the field of zinc ion battery electrolytes. Zinc salt and ethylene glycol are blended to form a deep eutectic solution to dissolve polyvinyl alcohol, and the eutectic gel electrolyte is prepared through a freeze-thaw method. According to the gel electrolyte, under the conditions that an aqueous solution is not introduced to dissolve the polyvinyl alcohol and the gel electrolyte does not need to be soaked in an aqueous electrolyte, the freezing point of the gel electrolyte is effectively reduced, and adverse side reactions such as hydrogen evolution, zinc negative electrode corrosion and dendritic crystal growth induced by active water molecules are inhibited. The eutectic gel electrolyte has the characteristics of wide voltage window and wide temperature range, when the eutectic gel electrolyte is used for the zinc ion battery, the stability of a zinc negative electrode can be improved, the working voltage (2.6 V) of the zinc ion battery is widened, and the normal use of the zinc ion battery at the ultralow temperature (-80 DEG C and below) is met.

Description

Technical Field

[0001] This invention relates to a wide-temperature-range, wide-voltage eutectic gel electrolyte for zinc-ion batteries, its preparation method, and its application, belonging to the field of zinc-ion battery electrolytes. Background Technology

[0002] Aqueous zinc-ion batteries are considered strong contenders for next-generation energy storage technology due to their safety, low cost, and environmental friendliness. The electrolyte, as the third electrode, plays a crucial role in the overall performance of the battery. While traditional aqueous liquid electrolytes possess high ionic conductivity, they also present several significant challenges. The relatively high reactivity between the aqueous solution and the zinc anode can easily induce adverse reactions such as hydrogen evolution, zinc corrosion, and zinc dendrite formation, reducing the battery's electrochemical stability. Furthermore, the low electrochemical window of aqueous solutions limits the battery's operating voltage, and the use of aqueous electrolytes also carries the risk of leakage.

[0003] To overcome these shortcomings, researchers have proposed developing gel electrolytes to replace aqueous electrolytes. Gel electrolytes can significantly reduce the water content inside the battery, weakening various adverse reactions induced by water molecules, and also improve the battery's flexibility and safety. However, existing gel electrolytes still face many problems: they require immersion in aqueous electrolytes, have low ionic conductivity, poor electrode compatibility, poor mechanical properties, and are prone to freezing at low temperatures. These limitations make it difficult to fundamentally improve the problems faced by zinc-ion batteries and broaden their application prospects.

[0004] Therefore, developing an antifreeze gel electrolyte with excellent mechanical properties, high ionic conductivity, high structural stability, and interfacial compatibility is key to promoting the commercialization of aqueous zinc-ion batteries. Summary of the Invention

[0005] To address the aforementioned issues, this invention utilizes a deep eutectic solution formed by blending zinc salt and ethylene glycol to dissolve polyvinyl alcohol, and prepares a eutectic gel electrolyte via a freeze-thaw method. This gel electrolyte effectively lowers the freezing point and suppresses adverse side reactions induced by active water molecules, such as hydrogen evolution, zinc anode corrosion, and dendrite growth, without introducing an aqueous solution to dissolve the polyvinyl alcohol or requiring soaking in an aqueous electrolyte. The eutectic gel electrolyte exhibits a wide voltage window and a wide temperature range. When used in zinc-ion batteries, it can improve the stability of the zinc anode, broaden the operating voltage of the zinc-ion battery (2.6V), and meet the normal operation requirements of zinc-ion batteries at ultra-low temperatures (-80℃ and below).

[0006] The first objective of this invention is to provide a method for preparing a eutectic gel electrolyte, comprising the steps of: (1) A deep eutectic solution was obtained by mixing hydrogen bond acceptor Zn(BF4)2 salt and hydrogen bond donor ethylene glycol in a molar ratio of 1~2:1~8 and stirring to dissolve. (2) Polyvinyl alcohol and nanofiller cotton linter pulp were added to a deep eutectic solution to obtain a gel prepolymer solution; (3) Freeze the obtained gel prepolymer solution to obtain a eutectic gel electrolyte; The amount of polyvinyl alcohol added is 5-20 wt% of the deep eutectic solution; the amount of cotton linter pulp added is 0.2-2 wt% of the deep eutectic solution. Optionally, the amount of polyvinyl alcohol added is 10-20 wt% of the deep eutectic solution; the amount of cotton linter pulp added is 0.5-1.5 wt% of the deep eutectic solution. Optionally, the amount of polyvinyl alcohol added is 15-20 wt% of the deep eutectic solution; the amount of cotton linter pulp added is 1-1.5 wt% of the deep eutectic solution. Optionally, the molar ratio of hydrogen bond acceptor Zn(BF4)2 salt to hydrogen bond donor ethylene glycol is 1~2:1~6; Optionally, the molar ratio of the hydrogen bond acceptor Zn(BF4)2 salt to the hydrogen bond donor ethylene glycol is 1~2:1~4.

[0007] In one embodiment, the stirring and dissolving conditions in step (1) are 60~90℃ for 1~5 h; Optionally, the stirring and dissolving conditions in step (1) are 70~90℃ for 2~4 h. Optionally, the stirring and dissolving conditions in step (1) are 80~90℃ for 2~4 h.

[0008] In one embodiment, the freezing in step (3) is freezing at -20~-70℃ for 10~48 h; Optionally, the freezing in step (3) is freezing at -20~-50℃ for 12~48 h; Optionally, the freezing in step (3) is performed at -20 to -40°C for 24 to 48 hours; Optionally, the freezing in step (3) is freezing at -20~-40℃ for 36~48 h.

[0009] A second objective of this invention is to provide a eutectic gel electrolyte prepared by any of the methods described above.

[0010] A third objective of this invention is to provide a method for improving the performance of zinc-ion batteries, using a eutectic gel electrolyte to prepare the battery; the method for preparing the eutectic gel electrolyte includes the following steps: (1) A deep eutectic solution was obtained by mixing hydrogen bond acceptor Zn(BF4)2 salt and hydrogen bond donor ethylene glycol in a molar ratio of 1~2:1~8 and stirring to dissolve. (2) Polyvinyl alcohol and nanofiller cotton linter pulp were added to a deep eutectic solution to obtain a gel prepolymer solution; (3) Freeze the obtained gel prepolymer solution to obtain a eutectic gel electrolyte; The amount of polyvinyl alcohol added is 5-20 wt% of the deep eutectic solution; the amount of cotton linter pulp added is 0.2-2 wt% of the deep eutectic solution. Optionally, the amount of polyvinyl alcohol added is 10-20 wt% of the deep eutectic solution; the amount of cotton linter pulp added is 0.5-1.5 wt% of the deep eutectic solution. Optionally, the amount of polyvinyl alcohol added is 15-20 wt% of the deep eutectic solution; the amount of cotton linter pulp added is 1-1.5 wt% of the deep eutectic solution. Optionally, the molar ratio of hydrogen bond acceptor Zn(BF4)2 salt to hydrogen bond donor ethylene glycol is 1~2:1~6; Optionally, the molar ratio of the hydrogen bond acceptor Zn(BF4)2 salt to the hydrogen bond donor ethylene glycol is 1~2:1~4.

[0011] In one embodiment, the stirring and dissolving conditions in step (1) are 60~90℃ for 1~5 h; Optionally, the stirring and dissolving conditions in step (1) are 70~90℃ for 2~4 h. Optionally, the stirring and dissolving conditions in step (1) are 80~90℃ for 2~4 h.

[0012] In one embodiment, the freezing temperature in step (3) is -20 to -70°C; Optionally, the freezing temperature in step (3) is -20 to -50°C; Optionally, the freezing temperature in step (3) is -20 to -40°C.

[0013] In one embodiment, the freezing time in step (3) is 10~48 h; Optionally, the freezing time in step (3) is 12~48 h; Optionally, the freezing time in step (3) is 24~48 h; Optionally, the freezing time in step (3) is 36 to 48 hours.

[0014] A fourth objective of this invention is to provide a zinc-ion battery prepared using the eutectic gel electrolyte described above.

[0015] In one embodiment, the zinc-ion battery is assembled using zinc foil as the negative electrode, V2O5, AC@MnO2 or AC as the positive electrode, the aforementioned eutectic gel electrolyte as the electrolyte, and a CR2032 battery case as the outer shell.

[0016] The fifth objective of this invention is to enhance the application of the aforementioned eutectic gel electrolyte in battery fabrication.

[0017] Beneficial effects (1) The eutectic gel electrolyte prepared by the present invention is water-free. When used in zinc-ion batteries, there are no adverse reactions such as hydrogen evolution and corrosion on the zinc anode surface. The zinc anode has high utilization rate and reversibility.

[0018] (2) The eutectic gel electrolyte prepared by the present invention has a dense hydrogen bond cross-linking structure and abundant pore structure. When used in zinc-ion batteries, it has excellent ionic conductivity and can effectively improve the electrochemical reaction activity of zinc-ion batteries.

[0019] (3) The eutectic gel electrolyte prepared by the present invention is suitable for various zinc-ion batteries such as vanadium-based, manganese-based and zinc-ion hybrid capacitors, and can improve the voltage window of these zinc-ion batteries to 2.6V.

[0020] (4) When the eutectic gel electrolyte prepared by the present invention is used in zinc-ion batteries, it can operate normally at ultra-low temperatures of -80°C and below. Attached Figure Description

[0021] Figure 1 This is a comparison chart of the ionic conductivity of the eutectic gel electrolyte and the liquid electrolyte obtained in this invention.

[0022] Figure 2 This is a SEM image of the eutectic gel electrolyte obtained in this invention.

[0023] Figure 3 This is a diagram illustrating the compatibility between the eutectic gel electrolyte obtained in this invention and the metal electrode.

[0024] Figure 4 This is a comparison diagram of the eutectic gel electrolyte and liquid electrolyte obtained in this invention before and after freezing at -80°C.

[0025] Figure 5 This is a comparison chart of the cycle stability of the eutectic gel electrolyte and the liquid electrolyte obtained in this invention.

[0026] Figure 6 The graphs show the charge-discharge curves of the eutectic gel electrolyte obtained in this invention in Zn / / V2O5, Zn / / AC@MnO2, and Zn / / AC batteries.

[0027] Figure 7The diagram shows the effect of the eutectic gel electrolyte obtained in this invention powering an LED lamp at -80°C and in a liquid nitrogen environment. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, where specific conditions are not specified, are generally performed under conventional conditions in the art. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar with the art.

[0029] Raw material source: Zn(BF4)2 salt, Zn(ClO4)2 salt, Zn(OAc)2 salt, and V2O5 were purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Ethylene glycol was purchased from Sinopharm Chemical Reagent Co., Ltd. Polyvinyl alcohol, polyacrylic acid, polyacrylamide, and polyethylene glycol were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. MnO2 was purchased from Zhejiang Hanwei Technology Co., Ltd. Activated carbon (AC, YP-50F) was purchased from Kuraray. The nano-filler cotton linter pulp was purchased from Shandong Yinying Chemical Fiber Co., Ltd. (α-cellulose content > 95%). The nanofiller bleached softwood pulp was purchased from Canada. The Lion Brand nanofiller bleached hardwood pulp was purchased from Canada; Lion Brand. The measurement methods involved in the examples are as follows: 1. Determination of cyclic stability The Zn / / Zn symmetric cells were assembled and tested on the Blue Electric CT2001A battery testing system.

[0030] 2. Compatibility determination The compatibility of electrodes with different metals (zinc, copper, titanium, stainless steel) was evaluated using eutectic gel electrolytes.

[0031] Place the eutectic gel electrolyte on the metal electrode and observe whether the electrode falls off.

[0032] 3. Measurement of conductivity By assembling SS / / SS batteries, in 10 -2 ~10 5 EIS testing was performed at Hz, and the corresponding ionic conductivity σ was calculated based on the resistance value obtained from the EIS curve. The calculation formula is as follows: σ = L / RS Where L is the thickness of the eutectic gel electrolyte / separator, R is the resistance value obtained by EIS test of SS / / SS battery, and S is the contact area between the eutectic gel electrolyte / separator and the electrode.

[0033] 4. Mechanical strength test Using an electronic universal testing machine (MIT-1KN) at 20 mm·min -1 The strength of the sample was obtained by stretching a 2 cm × 4 cm rectangular eutectic gel electrolyte / diaphragm to the point of fracture at a certain stretching rate.

[0034] Example 1: A wide-temperature-range, wide-voltage eutectic gel electrolyte for zinc-ion batteries A method for preparing a wide-temperature-range, wide-voltage eutectic gel electrolyte for zinc-ion batteries includes the following steps: (1) The hydrogen bond acceptor Zn(BF4)2 salt and the hydrogen bond donor ethylene glycol were mixed in a molar ratio of 1:4 and stirred at 80°C for 3 h to obtain a deep eutectic solvent. (2) Add 10 wt% of polymer polyvinyl alcohol and 1 wt% of nanofiller cotton linter pulp to a deep eutectic solvent to obtain a gel prepolymer solution. (3) Freeze the obtained gel prepolymer at -20°C for 36 hours to obtain eutectic gel electrolyte.

[0035] Comparative Example 1: Replacing Zn(BF4)2 salt with Zn(ClO4)2 salt The specific implementation method is the same as in Example 1, except that the Zn(BF4)2 salt in step (1) is replaced with Zn(ClO4)2 salt, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0036] Comparative Example 2: Replacing Zn(BF4)2 salt with Zn(OAc)2 salt The specific implementation method is the same as in Example 1, except that the Zn(BF4)2 salt in step (1) is replaced with Zn(OAc)2 salt, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0037] Comparative Example 3: The stirring temperature was changed to 60℃ The specific implementation method is the same as in Example 1, except that the stirring temperature in step (1) is changed to 60°C, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0038] Comparative Example 4: The stirring temperature was changed to 70℃ The specific implementation method is the same as in Example 1, except that the stirring temperature in step (1) is changed to 70°C, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0039] Comparative Example 5: The stirring temperature was changed to 90℃ The specific implementation method is the same as in Example 1, except that the stirring temperature in step (1) is changed to 90°C, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0040] Comparative Example 6: Polyvinyl alcohol was replaced with polyacrylic acid The specific implementation method is the same as in Example 1, except that polyvinyl alcohol in step (2) is replaced with polyacrylic acid, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0041] Comparative Example 7: Polyvinyl alcohol was replaced with polyacrylamide The specific implementation method is the same as in Example 1, except that polyvinyl alcohol in step (2) is replaced with polyacrylamide, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0042] Comparative Example 8: Polyvinyl alcohol was replaced with polyethylene glycol. The specific implementation method is the same as in Example 1, except that polyvinyl alcohol in step (2) is replaced with polyethylene glycol, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0043] Comparative Example 9: Changing the molar ratio of hydrogen bond acceptors to hydrogen bond donors The specific implementation method is the same as in Example 1, except that the molar ratio of hydrogen bond acceptor to hydrogen bond donor in step (1) is changed to 1:2, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0044] Comparative Example 10: Changing the molar ratio of hydrogen bond acceptors to hydrogen bond donors The specific implementation method is the same as in Example 1, except that the molar ratio of hydrogen bond acceptor to hydrogen bond donor in step (1) is changed to 1:6, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0045] Comparative Example 11: Changing the molar ratio of hydrogen bond acceptors to hydrogen bond donors The specific implementation method is the same as in Example 1, except that the molar ratio of hydrogen bond acceptor to hydrogen bond donor in step (1) is changed to 1:8, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0046] Comparative Example 12: Changing the amount of polyvinyl alcohol added The specific implementation method is the same as in Example 1, except that the amount of polyvinyl alcohol added in step (2) is changed to 5 wt%, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0047] Comparative Example 13: Changing the amount of polyvinyl alcohol added The specific implementation method is the same as in Example 1, except that the amount of polyvinyl alcohol added in step (2) is changed to 15 wt%, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0048] Comparative Example 14: Changing the amount of polyvinyl alcohol added The specific implementation method is the same as in Example 1, except that the amount of polyvinyl alcohol added in step (2) is changed to 20 wt%, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0049] Comparative Example 15: Cotton lint pulp without added nanofiller The specific implementation method is the same as in Example 1, except that no nanofiller cotton lint pulp is added in step (2), while the other steps remain the same to prepare a eutectic gel electrolyte.

[0050] Comparative Example 16: Changing the amount of nanofiller cotton lint pulp added The specific implementation method is the same as in Example 1, except that the amount of nanofiller cotton lint pulp added in step (2) is changed to 2 wt%, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0051] Comparative Example 17: Changing the freezing time The specific implementation method is the same as in Example 1, except that the freezing time in step (3) is changed to 12 h, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0052] Comparative Example 18: Changing the freezing time The specific implementation method is the same as in Example 1, except that the freezing time in step (3) is changed to 24 h, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0053] Comparative Example 19: Changing the freezing time The specific implementation method is the same as in Example 1, except that the freezing time in step (3) is changed to 48 h, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0054] Comparative Example 20: Replacing nanofiller cotton lint pulp with bleached softwood pulp The specific implementation method is the same as in Example 1, except that the nanofiller cotton lint pulp in step (2) is replaced with bleached softwood pulp, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0055] Comparative Example 21: Replacing nanofiller cotton lint pulp with bleached hardwood pulp The specific implementation method is the same as in Example 1, except that the nanofiller cotton lint pulp in step (2) is replaced with bleached hardwood pulp, while the other steps remain the same, and a eutectic gel electrolyte is prepared.

[0056] Comparative Example 22: Preparation of Conventional Aqueous Electrolytes A certain amount of ZnSO4 was dissolved in a certain amount of deionized water to obtain a ZnSO4 electrolyte with a concentration of 2 mol / L.

[0057] Example 2: Performance determination of eutectic gel electrolyte 1. Determination of physical properties The physical properties of the eutectic gel electrolytes prepared in Example 1 and Comparative Examples 1-21 were measured, and the results are shown in Table 1.

[0058] Table 1

[0059] The results showed that the eutectic gel electrolyte prepared by selecting Zn(BF4)2 and ethylene glycol as hydrogen bond acceptors / donors and cotton linter pulp as nanofiller had the best mechanical properties and ionic conductivity.

[0060] in, Figure 1 The figure shows a comparison of the ionic conductivity of the eutectic gel electrolyte prepared in Example 1 and the aqueous electrolyte prepared in Comparative Example 22. The results show that the eutectic gel electrolyte has a higher ionic conductivity than the conventional commercial zinc sulfate electrolyte, which is beneficial to improving the electrochemical performance of zinc-ion batteries.

[0061] 2. Observation using a scanning electron microscope The eutectic gel electrolyte prepared in Example 1 was observed using a scanning electron microscope, and the results are as follows: Figure 2 As shown, the results indicate that the eutectic gel electrolyte has a rich three-dimensional interconnected network structure, which can provide more effective ion channels for zinc ion transport.

[0062] 3. Compatibility testing The eutectic gel electrolyte prepared in Example 1 was used to determine its compatibility with the electrode. The results are as follows: Figure 3 As shown.

[0063] The results show that the eutectic gel electrolyte has good compatibility with each metal electrode, which is beneficial to improving the stability of the zinc anode interface and the uniform interface transport efficiency of zinc ions.

[0064] 4. Freezing treatment The eutectic gel electrolyte prepared in Example 1 and the liquid electrolyte prepared in Comparative Example 22 were frozen at -80°C.

[0065] The results are as follows Figure 4As shown, the results indicate that the eutectic condensed electrolyte did not freeze after being placed at -80℃ for 3 hours, while the conventional diaphragm-zinc sulfate electrolyte showed obvious freezing after being placed at -80℃ for 3 hours.

[0066] Example 3: Preparation of Zn / / V2O5 battery The eutectic gel electrolyte prepared in Example 1 was used to prepare a Zn / / V2O5 battery, and the steps are as follows: Zinc foil was used as the negative electrode, V2O5 as the positive electrode, the electrolyte was the eutectic gel electrolyte obtained in Example 1, and a CR2032 battery case was used as the outer shell to assemble a Zn / / V2O5 battery.

[0067] Example 4: Preparation of Zn / / AC@MnO2 battery Zinc foil was used as the negative electrode, AC@MnO2 as the positive electrode, the electrolyte was the eutectic gel electrolyte obtained in Example 1, and CR2032 battery case was used as the outer shell to assemble the Zn / / AC@MnO2 battery.

[0068] Example 5: Preparation of Zn / / AC Battery Zinc foil is used as the negative electrode, AC is used as the positive electrode, the electrolyte is the eutectic gel electrolyte obtained in Example 1, and CR2032 battery case is used as the outer shell to assemble a Zn / / AC battery.

[0069] Comparative Example 23: Preparation of a conventional Zn / / V2O5 battery The specific implementation method is the same as in Example 3, except that the electrolyte is prepared using Comparative Example 22, while the other steps remain the same, and a conventional Zn / / V2O5 battery is assembled.

[0070] Example 6: Battery Performance Measurement 1. Cyclic stability determination The batteries prepared in Example 5 and Comparative Example 23 were used to determine their cycle stability, and the results are as follows: Figure 5 As shown, the results indicate that this eutectic gel electrolyte exhibits superior cycling stability compared to conventional commercial zinc sulfate electrolytes.

[0071] 2. Charge and discharge performance testing The batteries prepared in Examples 3-5 were used to measure their charge-discharge performance, and the results are as follows: Figure 6 As shown, the results indicate that the eutectic gel electrolyte is suitable for various zinc-ion batteries (Zn / / AC@MnO2, Zn / / V2O5, and Zn / / AC). When used in these three zinc-ion batteries, the voltage can reach 2.6 V, which is much higher than that of Zn / / AC@MnO2 (1.8 V), Zn / / V2O5 (1.6 V), and Zn / / AC (1.8 V) using conventional zinc sulfate electrolytes.

[0072] 3. Battery's temperature tolerance Take the battery prepared in Example 3 and place it in an environment of -80°C and liquid nitrogen (-196°C) to observe the power supply of the LED light.

[0073] The results are as follows Figure 7 As shown, the results indicate that the eutectic gel electrolyte obtained in Example 1 can still power LEDs normally even when kept at -80°C for 1 h or even at -196°C.

[0074] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a eutectic gel electrolyte, characterized in that, Including the following steps: (1) A deep eutectic solution was obtained by mixing hydrogen bond acceptor Zn(BF4)2 salt and hydrogen bond donor ethylene glycol in a molar ratio of 1~2:1~8 and stirring to dissolve. (2) Polyvinyl alcohol and nanofiller cotton linter pulp were added to a deep eutectic solution to obtain a gel prepolymer solution; (3) Freeze the obtained gel prepolymer solution to obtain a eutectic gel electrolyte; The amount of polyvinyl alcohol added is 5-20 wt% of the deep eutectic solution; the amount of cotton linter pulp added is 0.2-2 wt% of the deep eutectic solution.

2. The method according to claim 1, characterized in that, The stirring and dissolving conditions in step (1) are 60~90℃ for 1~5 h.

3. The method according to claim 1, characterized in that, The freezing process in step (3) involves freezing at -20 to -70°C for 10 to 48 hours.

4. The eutectic gel electrolyte prepared by any one of claims 1 to 3.

5. A method for improving the performance of zinc-ion batteries, characterized in that, A battery is prepared using a eutectic gel electrolyte; the preparation method of the eutectic gel electrolyte includes the following steps: (1) A deep eutectic solution was obtained by mixing hydrogen bond acceptor Zn(BF4)2 salt and hydrogen bond donor ethylene glycol in a molar ratio of 1~2:1~8 and stirring to dissolve. (2) Polyvinyl alcohol and nanofiller cotton linter pulp were added to a deep eutectic solution to obtain a gel prepolymer solution; (3) Freeze the obtained gel prepolymer solution to obtain a eutectic gel electrolyte; The amount of polyvinyl alcohol added is 5-20 wt% of the deep eutectic solution; the amount of cotton linter pulp added is 0.2-2 wt% of the deep eutectic solution.

6. The method according to claim 5, characterized in that, The stirring and dissolving conditions in step (1) are 60~90℃ for 1~5 h.

7. The method according to claim 5, characterized in that, The freezing temperature in step (3) is -20~-70℃.

8. The method according to claim 5, characterized in that, The freezing time in step (3) is 10~48 h.

9. A zinc-ion battery, characterized in that, It was prepared using the eutectic gel electrolyte according to claim 4.

10. The application of the eutectic gel electrolyte of claim 4 in battery preparation.

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