A zinc ion battery gel electrolyte and a preparation method thereof

Abstract

The application discloses a kind of zinc ion battery gel electrolyte and preparation method thereof.The gel electrolyte preparation method is: take zinc trifluoromethane sulfonate and acrylamide to deionized water, stirring to completely dissolve, then add N, N'-methylene bisacrylamide, continue to stir to solution sequentially add ammonium persulfate and bismuth sulfide nanowire and keep violent stirring, after ultrasonic treatment the mixture is heated in drying oven and polymerized to obtain gel electrolyte.The electrolyte of the application can withstand the expansion and shrinkage of electrode during charging and discharging, reduce the rupture and perforation of diaphragm, prevent the short circuit of positive and negative electrode, can reduce the tip effect caused by uneven electric field distribution and inhibit dendrite growth.Especially, the introduced bismuth sulfide can effectively promote the desolvation process of Zn 2+ , reduce the interface desolvation energy barrier, improve reaction kinetics, inhibit the tip effect caused by uneven electric field distribution, synergistically inhibit the growth of zinc dendrite, improve the cycle stability and safety of battery.

Description

Technical Field

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

[0002] With the increasing severity of global climate change, reducing dependence on fossil fuels and promoting the large-scale application of renewable energy sources such as solar and wind power has become a global consensus. However, renewable energy sources such as solar, wind, and tidal power are intermittent and unstable, requiring efficient energy storage systems to achieve stable power output and supply-demand balance. Aqueous zinc batteries stand out due to their unique advantages. Zinc has vast global reserves and is inexpensive, making it suitable for large-scale applications. Aqueous zinc batteries use water-based electrolytes, which not only reduce costs but also completely eliminate the safety hazards of flammable and explosive organic electrolytes, significantly improving battery safety. From a performance perspective, zinc has a high theoretical specific capacity (820 mAh / g) and a suitable voltage window, giving aqueous zinc batteries a potential advantage in energy density. However, aqueous zinc batteries still face many challenges in practical applications. For example, the zinc anode is prone to dendrite formation during charging and discharging, which may lead to short circuits or even safety hazards; the zinc anode is also prone to side reactions such as hydrogen evolution and corrosion in aqueous electrolytes, reducing battery efficiency and lifespan.

[0003] The commonly used separator in aqueous zinc batteries is the glass fiber separator. However, the uneven distribution of fiber size and pore size inside the separator can easily lead to uneven distribution of electric field and electrolyte ions. At the same time, under the influence of the "point effect", dendrites can easily pierce the separator, causing the battery to short circuit. In addition, the hydrogen evolution reaction (HER) triggered by water electrolysis, along with the generation of byproducts such as basic zinc salts, further consumes the electrolyte, resulting in low coulombic efficiency and short service life of aqueous zinc batteries, which seriously hinders the practical application of zinc batteries. Summary of the Invention

[0004] Technical problem solved: To address the above-mentioned technical problems, this invention provides a zinc-ion battery gel electrolyte and its preparation method, which significantly improves the safety and stability of the battery, extends the cycle life of the battery, and has good repeatability and potential for large-scale production.

[0005] Technical solution: A method for preparing a zinc-ion battery gel electrolyte, comprising the following steps: Step 1: Add zinc trifluoromethanesulfonate and acrylamide to deionized water and stir until completely dissolved to obtain solution A; Step 2: Add ammonium persulfate to solution A and stir until completely dissolved to obtain solution B; Step 3: Add N,N′-methylenebisacrylamide to solution B and continue stirring to obtain solution C; Step 4: Add bismuth sulfide to solution C, stir, and sonicate to obtain a mixture; Step 5: Inject the mixture into a custom mold and thermally polymerize it in a drying oven to obtain the gel electrolyte.

[0006] Preferably, the concentration of zinc trifluoromethanesulfonate in solution A is 0.9~1g / ml, and the concentration of acrylamide is 0.3g / ml.

[0007] Preferably, the stirring speed in steps one and two is 200~300 r / min, and the stirring time is 15~20 min.

[0008] Preferably, the concentration of ammonium persulfate in solution B is 3 mg / ml.

[0009] Preferably, the concentration of N,N′-methylenebisacrylamide in solution C is 0.6 mg / ml.

[0010] Preferably, the stirring speed in step three is 200~300 r / min, and the time is 1~2 h.

[0011] Preferably, the concentration of bismuth sulfide in solution C is 1 mg / ml.

[0012] Preferably, in step four, the stirring speed is 400~500 r / min and the time is 5~10 min; the ultrasonic treatment power is 100~150 W, the temperature is 25~40℃, and the time is 7~12 min.

[0013] Preferably, the temperature for thermal polymerization in step five is 45°C, and the time is 4-5 hours.

[0014] The zinc-ion battery gel electrolyte prepared by the above method.

[0015] Beneficial effects: This invention can solve the problems of zinc anodes easily forming dendrites during charging and discharging, which may lead to battery short circuits or even safety hazards; zinc anodes are prone to hydrogen evolution and corrosion side reactions in aqueous electrolytes, which reduce battery efficiency and lifespan; and the hydrogen evolution reaction (HER) caused by water electrolysis, accompanied by the generation of byproducts such as basic zinc salts, further consumes the electrolyte, resulting in low coulombic efficiency and short lifespan of aqueous zinc batteries, which seriously hinders the practical application of zinc batteries.

[0016] Specifically, this invention provides a gel electrolyte for zinc-ion batteries, which uses hydrogel to replace the traditional separator and incorporates zinc trifluoromethanesulfonate in situ into the gel matrix to replace the liquid electrolyte. Compared to glass fiber separators, this gel electrolyte has superior flexibility and tensile strength, effectively buffering the volume expansion and contraction of the electrodes during charging and discharging, avoiding direct contact short circuits between the positive and negative electrodes caused by separator rupture or perforation, and significantly improving battery safety and structural stability.

[0017] This invention introduces bismuth sulfide nanowires into a gel electrolyte, utilizing their unique interfacial effect to significantly accelerate Zn production. 2+ The desolvation process reduces the interfacial desolvation energy barrier, improves ion transport kinetics, thereby effectively inhibiting the growth of zinc dendrites, enhancing electrode interface stability, and extending the cycle life of the battery.

[0018] This invention uses a gel electrolyte instead of a liquid electrolyte, which can effectively avoid side reactions caused by direct contact between the electrolyte and the electrode, reduce the generation of interfacial byproducts, improve the electrochemical reversibility of the battery, and further enhance the cycle stability and capacity retention of the battery.

[0019] This invention uses a thermal polymerization method to prepare gel electrolytes. The process is simple, the raw materials are readily available, the reaction conditions are mild, and it has good repeatability and potential for large-scale production. It is suitable for practical applications of high-performance zinc-ion batteries. Attached Figure Description

[0020] Figure 1 This is a comparison chart of ion transport number tests for symmetric batteries assembled with gel electrolytes prepared in Example 1 and Comparative Examples 1 and 2. Figure 2 This is a comparison chart of the puncture intensity of the gel electrolytes prepared in Example 1 and Comparative Examples 1 and 2; Figure 3 This is a comparison of the scanning voltammetric characteristic curves of the symmetric cells assembled with gel electrolytes prepared in Example 1 and Comparative Examples 1 and 2 at a scan rate of 1 mV / s. Figure 4 The symmetric cells assembled from the gel electrolytes prepared in Example 1 and Comparative Example 1 were used in a 0.5 mAh cm⁻¹ battery. -2 Comparison chart of rate performance tests at current density. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1

[0022] This embodiment provides a method for preparing a zinc-ion battery gel electrolyte, including the following steps: Step 1: Take 4.5354 g Zn(OTf)2 and 1.5 g acrylamide (AM) and add them to 5 ml of deionized water. Stir until completely dissolved. Use a magnetic stirrer with a stirring speed of 200 r / min and a stirring time of 15 minutes. Step 2: Add 15 mg of ammonium persulfate (APS) to the solution and stir vigorously until completely dissolved. Use a magnetic stirrer with a stirring speed of 300 r / min and a stirring time of 20 minutes. Step 3: Add 3 mg of N,N′-methylenebisacrylamide (MBA) and continue stirring the resulting mixture for several hours. Use a magnetic stirrer with a stirring speed of 300 r / min and a stirring time of 2 hours. Step 4: Add 5 mg of bismuth sulfide (Bi2S3) to the solution, stir vigorously and sonicate. The stirring speed of the magnetic stirrer is 400 r / min, the stirring time is controlled at 5 minutes, the power of the sonication is 150 W, the temperature is controlled at 25 ℃, and the sonication time is 10 minutes. Step 5: Inject the resulting mixture into a custom mold and place it in a drying oven at 45 ℃ for 4 hours to thermally polymerize, thereby obtaining a zinc-ion battery gel electrolyte. Example 2

[0023] This embodiment provides a method for preparing a zinc-ion battery gel electrolyte, including the following steps: Step 1: Take 4.5354 g Zn(OTf)2 and 1.5 g acrylamide (AM) and add them to 5 ml of deionized water. Stir until completely dissolved. Use a magnetic stirrer with a stirring speed of 300 r / min and a stirring time of 10 minutes. Step 2: Add 15 mg of ammonium persulfate (APS) to the solution and stir vigorously until completely dissolved. Use a magnetic stirrer with a stirring speed of 200 r / min and a stirring time of 20 minutes. Step 3: Add 3 mg of N,N′-methylenebisacrylamide (MBA) and continue stirring the resulting mixture for several hours. Use a magnetic stirrer with a stirring speed of 300 r / min and a stirring time of 1 hour. Step 4: Add 5 mg of bismuth sulfide (Bi2S3) to the solution, stir vigorously and sonicate. The stirring speed of the magnetic stirrer is 400 r / min, the stirring time is controlled at 5 minutes, the power of the sonication is 150 W, the temperature is controlled at 25 ℃, and the sonication time is 10 minutes. Step 5: Inject the resulting mixture into a custom mold and place it in a drying oven at 45 ℃ for 4 hours to thermally polymerize, thereby obtaining a zinc-ion battery gel electrolyte. Example 3

[0024] This embodiment provides a method for preparing a zinc-ion battery gel electrolyte, including the following steps: Step 1: Take 4.5354 g Zn(OTf)2 and 1.5 g acrylamide (AM) and add them to 5 ml of deionized water. Stir until completely dissolved. Use a magnetic stirrer with a stirring speed of 200 r / min and a stirring time of 15 minutes. Step 2: Add 15 mg of ammonium persulfate (APS) to the solution and stir vigorously until completely dissolved. Use a magnetic stirrer with a stirring speed of 200 r / min and a stirring time of 20 minutes. Step 3: Add 3 mg of N,N′-methylenebisacrylamide (MBA), and continue stirring the resulting mixture for several hours. Use a magnetic stirrer with a stirring speed of 300 r / min and a stirring time of 1.5 hours. Step 4: Add 5 mg of bismuth sulfide (Bi2S3) to the solution, stir vigorously and sonicate. The stirring speed of the magnetic stirrer is 400 r / min, the stirring time is controlled at 5 minutes, the power of the sonication is 150 W, the temperature is controlled at 25 ℃, and the sonication time is 10 minutes. Step 5: Inject the resulting mixture into a custom mold and place it in a drying oven at 45 ℃ for 4 hours to thermally polymerize, thereby obtaining a zinc-ion battery gel electrolyte. Comparative Example 1

[0025] This comparative example provides a method for preparing a zinc-ion battery gel electrolyte, including the following steps: Step 1: Take 4.5354 g Zn(OTf)2 and 1.5 g acrylamide (AM) and add them to 5 ml of deionized water. Stir until completely dissolved. Use a magnetic stirrer with a stirring speed of 200 r / min and a stirring time of 15 minutes. Step 2: Add 15 mg of ammonium persulfate (APS) to the solution and stir vigorously until completely dissolved. Use a magnetic stirrer with a stirring speed of 300 r / min and a stirring time of 20 minutes. Step 3: Add 3 mg of N,N′-methylenebisacrylamide (MBA) and continue stirring the resulting mixture for several hours. Use a magnetic stirrer with a stirring speed of 300 r / min and a stirring time of 2 hours. Step 4: Inject the obtained solution into a custom mold and place it in a drying oven at 45 ℃ for 4 hours to obtain a zinc-ion battery gel electrolyte. Comparative Example 2

[0026] This comparative example uses commercially available glass fiber diaphragms directly.

[0027] Assemble symmetrical cells Battery assembly method: Prepare two zinc sheets, one spacer, and one spring contact. First, place the spring contact and spacer in the negative electrode shell of the CR 2032 battery from bottom to top. Then, place the pure zinc sheet in the middle of the spacer, ensuring that the spring contact and spacer are aligned. Next, place the previously prepared gel electrolyte directly above the zinc sheet using tweezers. Finally, place the other zinc sheet in the middle of the gel electrolyte and cover it with the positive electrode shell. Perform the sealing operation using a battery packaging machine to assemble the CR 2032 button cell.

[0028] The above-mentioned batteries were subjected to AC impedance testing and chronoamperometry testing on an electrochemical workstation, and the results are as follows: Figure 1 As shown, the symmetrical cell assembled in Example 1 reaches steady state in a shorter time and with a more stable current compared to Comparative Example 1. The calculated ion transport number is also significantly increased, confirming a significant enhancement in interfacial transport kinetics and reaction kinetics. Simultaneously, the puncture intensity of Example 1 is compared with Comparative Examples 1 and 2. (See [reference needed]). Figure 2 It can be seen that Example 1 has a higher puncture intensity compared to Comparative Examples 1 and 2. Meanwhile, the scanning voltammograms of the battery at a scan rate of 1 mV / s are compared (see [reference needed]). Figure 3 As can be seen, the redox current of Example 1 is higher than that of the symmetrical cells assembled in Comparative Examples 1 and 2, confirming a significant enhancement in interfacial transport kinetics and reaction kinetics. Meanwhile, the rate performance tests of Example 1 and Comparative Example 1 are compared; see [link to relevant documentation]. Figure 4 It can be seen that, compared to the symmetrical battery assembled in Comparative Example 1, Example 1, even at 5 mAh cm⁻¹, -2 It maintains stable cycling even under high current, and the voltage hysteresis also decreases steadily as the current gradually decreases.

Claims

1. A method of preparing a zinc-ion battery gel electrolyte, characterized in that, The steps include the following: Step 1: Add zinc trifluoromethanesulfonate and acrylamide to deionized water and stir until completely dissolved to obtain solution A; Step 2: Add ammonium persulfate to solution A and stir until completely dissolved to obtain solution B; Step 3: Add N,N′-methylenebisacrylamide to solution B and continue stirring to obtain solution C; Step 4: Add bismuth sulfide to solution C, stir, and sonicate to obtain a mixture; Step 5: Inject the mixture into a custom mold and thermally polymerize it in a drying oven to obtain the gel electrolyte.

2. The method for preparing a zinc-ion battery gel electrolyte according to claim 1, characterized in that, The concentration of zinc trifluoromethanesulfonate in solution A is 0.9~1 g / ml, and the concentration of acrylamide is 0.3 g / ml.

3. The method for preparing a zinc-ion battery gel electrolyte according to claim 1, characterized in that, The stirring speed in steps one and two is 200-300 r / min, and the stirring time is 15-20 min.

4. The method for preparing a zinc-ion battery gel electrolyte according to claim 1, characterized in that, The concentration of ammonium persulfate in solution B is 3 mg / ml.

5. The method for preparing a zinc-ion battery gel electrolyte according to claim 1, characterized in that, The concentration of N,N′-methylenebisacrylamide in solution C is 0.6 mg / ml.

6. The method for preparing a zinc-ion battery gel electrolyte according to claim 1, characterized in that, In step three, the stirring speed is 200-300 r / min, and the time is 1-2 h.

7. The method for preparing a zinc-ion battery gel electrolyte according to claim 1, characterized in that, The bismuth sulfide concentration in solution C is 1 mg / ml.

8. The method for preparing a zinc-ion battery gel electrolyte according to claim 1, characterized in that, In step four, the stirring speed is 400-500 r / min and the time is 5-10 min; the ultrasonic treatment power is 100-150 W, the temperature is 25-40℃, and the time is 7-12 min.

9. The method for preparing a zinc-ion battery gel electrolyte according to claim 1, characterized in that, In step five, the temperature for thermal polymerization is 45°C, and the time is 4-5 hours.

10. A zinc-ion battery gel electrolyte prepared by the method of claim 1.

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