Hydrogel electrolyte and preparation method and application thereof

Abstract

The invention discloses a hydrogel electrolyte as well as a preparation method and application thereof. The hydrogel electrolyte comprises a polymer network formed by crosslinking a vinyl monomer, a crosslinking agent and an initiator, and zinc tetrafluoroborate contained in the polymer network. In the hydrogel electrolyte, Zn (BF4) 2 catalyzes the initiator to generate free radicals to initiate vinyl monomer polymerization; the hydrogel electrolyte has excellent anti-freezing capability, and can still play a role normally even at low temperature. The invention also provides a preparation method of the hydrogel electrolyte, which does not need illumination, heat and toxic coagulant, and can quickly form gel within 1 minute; the preparation process is energy-saving and environment-friendly, the synthetic route is simple, and large-scale production can be

Description

Technical Field

[0001] This invention relates to the field of new energy materials technology, and in particular to a hydrogel electrolyte, its preparation method, and its application. Background Technology

[0002] Flexible lithium-ion batteries are currently one of the most widely researched and applied types of flexible batteries. They typically use liquid electrolytes and possess good overall performance, but they pose a risk of electrolyte leakage after damage. Furthermore, the organic electrolytes used are toxic and flammable, resulting in poor safety performance. Therefore, developing flexible battery systems with high safety, low cost, and environmental friendliness is an important direction for future energy storage technology development. Hydrogel electrolyte (HE)-based zinc batteries possess characteristics such as flexibility, high theoretical capacity, environmental friendliness, low cost, and high safety, meeting the basic requirements of ideal flexible energy storage devices. However, the synthesis process of hydrogel electrolytes is currently complex, typically requiring light and heat, as well as toxic accelerators, resulting in high energy consumption and long synthesis times, especially at low temperatures.

[0003] Current technologies primarily address the challenges of flexible wearable zinc batteries by focusing on the mechanical properties of hydrogel electrolytes. Among these, the design of functionalized groups to mitigate issues such as hydrogen evolution, corrosion, and dendrite growth in the zinc anode has garnered significant attention. However, the synthesis of hydrogel electrolytes remains unresolved, and the laminated batteries assembled from them often face substantial interfacial polarization. Summary of the Invention

[0004] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a hydrogel electrolyte, its preparation method, and its application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a hydrogel electrolyte comprising a polymer network formed by crosslinking a vinyl monomer and a crosslinking agent and an initiator, and zinc tetrafluoroborate contained therein.

[0006] In this invention, zinc tetrafluoroborate can catalyze the initiator to generate free radicals, which initiate the polymerization of vinyl monomers to form a polymer network.

[0007] In some embodiments, the mass ratio of the vinyl monomer to the crosslinking agent is 1:(50-150); such as 1:(80-130), 1:(90-120), 1:100, 1:105, 1:110, 1:115, etc.

[0008] In some embodiments, the mass ratio of zinc tetrafluoroborate to vinyl monomer is (2-50):1; such as (2-40):1, (2-30):1, (8-13):1, (9-11):1, 9:1, 9.5:1, 10:1, 10.5:1, 11:1, etc.

[0009] In some embodiments, the mass percentage of zinc tetrafluoroborate in the hydrogel electrolyte is 10%-80%, such as 15%-70%, 15%-68%, etc.

[0010] In some embodiments, the mass ratio of the vinyl monomer to the initiator is (200-800):1; such as (300-600):1, 400:1, 450:1, 500:1, 550:1, etc.

[0011] In some embodiments, the vinyl monomer includes at least one of acrylamide (Am), N,N-dimethylacrylamide (DMAA), N-isopropylacrylamide (NIPAM), acrylic acid (AA), methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and sulfobetaine methacrylate (SBMA).

[0012] In some embodiments, the crosslinking agent includes at least one of N,N-methylenebisacrylamide (MBA), glutaraldehyde, and polyethylene glycol diacrylate.

[0013] In some embodiments, the initiator includes at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0014] A second aspect of the present invention provides a method for preparing the aforementioned hydrogel electrolyte, comprising the following steps: The hydrogel electrolyte is prepared by mixing zinc tetrafluoroborate, vinyl monomer and crosslinking agent, and then adding initiator to react.

[0015] In some embodiments, the reaction temperature is -50℃ to 30℃, such as -40℃ to 30℃, -30℃ to 30℃, -20℃ to 30℃, -10℃ to 30℃, 0 to 30℃, 20 to 30℃, 25℃, etc.; the reaction time is 30s to 120s, such as 40s to 80s, 50s, 60s, 70s, etc. In this invention, zinc tetrafluoroborate can catalyze the initiator to generate free radicals, initiating the rapid polymerization of vinyl monomers.

[0016] In some embodiments, the solvent used in the reaction includes at least one of water and an organic solvent.

[0017] In some embodiments, the organic solvent includes at least one of ethylene glycol, sorbitol, glycerol, and dimethyl sulfoxide.

[0018] A third aspect of the present invention provides a zinc battery comprising a positive electrode, a negative electrode, and a hydrogel electrolyte disposed between the positive and negative electrodes.

[0019] In some embodiments, the positive electrode includes zinc, copper, iodine / carbon composite material, vanadium pentoxide, air, manganese dioxide, Prussian blue and its derivatives.

[0020] In some embodiments, the negative electrode comprises zinc.

[0021] In some embodiments, the zinc battery includes a primary zinc battery and a secondary zinc battery.

[0022] A fourth aspect of the present invention provides a method for preparing the zinc battery described above, comprising the following steps: Zinc tetrafluoroborate, vinyl monomers, and crosslinking agents are mixed to obtain a precursor solution. The precursor solution is coated onto an electrode, an initiator is added, another electrode is placed, and after reaction, the zinc battery is obtained.

[0023] In this invention, a solid electrolyte interface (SEI) layer is formed in situ at the negative electrode, exhibiting strong interfacial adhesion, greatly reducing interfacial polarization, and alleviating dendrite growth; at the same time, it reduces the activity of interfacial water and reduces side reactions.

[0024] The beneficial effects of this invention are: In the hydrogel electrolyte of the present invention, Zn(BF4)2 catalytic initiator generates free radicals, which initiate the polymerization of vinyl monomers; the hydrogel electrolyte has excellent antifreeze ability and can still function normally even at low temperatures.

[0025] The hydrogel electrolyte preparation method of the present invention does not require light, heat, or toxic coagulants, and can rapidly gel within 1 minute even at low temperatures such as -40°C; the preparation process is energy-saving and environmentally friendly, the synthesis route is simple, and it can be mass-produced.

[0026] In the zinc battery of the present invention, an SEI layer is formed in situ on the negative electrode, exhibiting strong interfacial adhesion, greatly reducing interfacial polarization and alleviating dendrite growth; at the same time, it reduces the activity of interfacial water, reduces side reactions, and improves the overall electrochemical performance of the battery.

[0027] The zinc battery of the present invention can form an SEI layer in situ on the basis of a hydrogel electrolyte and be assembled into a zinc battery in situ, which is very convenient. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the rapid preparation process of ZCHE in Embodiment 1 of the present invention.

[0029] Figure 2 The images show the DSC curve (a), interface adhesion AFM image (b), and quantization result (c) of ZCHE in Embodiment 1 of the present invention.

[0030] Figure 3 The in-situ GC (a) of ZCHE obtained in Example 1 of the present invention, along with the corresponding Arrhenius curve and activation energy (b).

[0031] Figure 4 The images shown are XPS deep profile (a) and Top-sims (b) images of the SEI layer formed in situ by ZCHE obtained in Example 1 of this invention.

[0032] Figure 5 The ZCHE-based and ZE-based Zn||Zn symmetric cells obtained in Example 1 and Comparative Example 2 of this invention are compared at different current densities ( Figure 5 (a in the above figure) and different temperatures ( Figure 5 (Figure a below) Comparison of charge-discharge cycle curves and coulombic efficiency of Zn||Cu batteries under test conditions (b).

[0033] Figure 6 The ZCHE-based and ZE-based Zn||Zn symmetric cells obtained in Example 1 of this invention are at 1 mA / cm 2 1 mAh / cm 2 SEM image (a) and AFM image (b) of the surface after 20 cycles under test conditions.

[0034] Figure 7 The cycling curves of the ZCHE and ZE-based Zn||I2 full cells obtained in Example 1 of this invention are shown under 5 C test conditions. Detailed Implementation

[0035] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0036] In the following examples or comparative examples, the method for preparing the positive electrode material for the full cell is as follows: Iodine and YP80F are uniformly ground in a 1:1 ratio and then placed in a hydrothermal reactor and reacted at 120 °C for 6 hours. The resulting I2@YP80F powder, acetylene black, and polyvinylidene fluoride (PVDF) are sequentially dispersed in N-methylpyrrolidone (NMP) solvent at a weight ratio of 7:2:1, and continuously ground into a uniform slurry. Subsequently, the slurry is coated onto carbon paper using a blade coating method and dried overnight in an oven at 60 °C, finally obtaining an iodine surface loading of approximately 1-2 mg / cm³.-2 .

[0037] Example 1 This embodiment prepares a hydrogel electrolyte (ZCHE) and a zinc battery. The specific process is as follows: (1) Weigh 9.56 g Zn(BF4)2 and add it to 10 mL of deionized water while stirring to obtain a 4 M Zn(BF4)2 solution; (2) Add 1 g acrylamide (Am) and 10 mg N,N'-methylenebisacrylamide to the above solution and stir at the same time to obtain an electrolyte precursor solution; (3) Add 10 mg APS to 2 mL of deionized water while stirring to obtain a 5 mg / mL APS solution; (4) Take 0.2 mL of electrolyte precursor solution, drop it onto the electrode surface, then drop 10 μL of APS solution, and then cover it with another electrode. After complete gelation within 1 min, the zinc battery assembled in situ is obtained.

[0038] Figure 1 The image shows the rapid preparation of the hydrogel electrolyte ZCHE in Example 1. It can be seen from the image that after the 4 M Zn(BF4)2 solution is mixed with the Am precursor solution, it can quickly form a gel within 1 min.

[0039] Example 2 This embodiment prepares a hydrogel electrolyte (ZCHE) and a zinc battery. The specific process is as follows: (1) Weigh 2.39 g, 4.78 g, 14.34 g and 23.9 g of Zn(BF4)2 respectively and add them to 10 mL of deionized water while stirring to obtain 1 M, 2 M, 6 M and 10 M Zn(BF4)2 solutions respectively; (2) Add 1 g of acrylamide and 10 mg of N,N'-methylenebisacrylamide to the above solution and stir at the same time to obtain a precursor electrolyte solution; (3) Add 10 mg APS to 2 mL of deionized water while stirring to obtain a 5 mg / mL APS solution; (4) Take 0.2 mL of electrolyte precursor solution, drop it onto the surface of an electrode with a diameter of 1.2 cm, then drop 10 μLAPS solution, and then cover it with another electrode. After complete gelation, an in-situ assembled zinc battery is obtained.

[0040] Example 3 This embodiment prepares a hydrogel electrolyte (ZCHE) and a zinc battery. The specific process is as follows: (1) Weigh 2.39 g, 4.78 g, 9.56 g, 14.34 g and 23.9 g of Zn(BF4)2 respectively and add them to 10 mL of deionized water while stirring to obtain 1 M, 2 M, 4 M, 6 M and 10 M Zn(BF4)2 solutions respectively; (2) Add 1 g of acrylic acid (AA) and 10 mg of MBA to the above solution and stir at the same time to obtain a precursor electrolyte solution; (3) Add 10 mg APS to 2 mL of deionized water while stirring to obtain a 5 mg / mL APS solution; (4) Take 0.2 mL of electrolyte precursor solution, drop it onto the surface of an electrode with a diameter of 1.2 cm, then drop 10 μLAPS solution, and then cover it with another electrode. After complete gelation, an in-situ assembled zinc battery is obtained.

[0041] Example 4 This embodiment prepares a hydrogel electrolyte (ZCHE) and a zinc battery. The specific process is as follows: (1) Weigh 2.39 g, 4.78 g, 9.56 g, 14.34 g and 23.9 g of Zn(BF4)2 respectively and add them to 10 mL of deionized water while stirring to obtain 1 M, 2 M, 4 M, 6 M and 10 M Zn(BF4)2 solutions respectively; (2) Mix 0.5 g AM and 0.5 g AA, 0.5 g AM and 0.5 g SBMA or 0.5 g AA and 0.5 g SBMA with 10 mg MBA and add to the above solution while stirring to obtain the precursor electrolyte solution; (3) Add 10 mg APS to 2 mL of deionized water while stirring to obtain a 5 mg / mL APS solution; (4) Take 0.2 mL of electrolyte precursor solution, drop it onto the surface of an electrode with a diameter of 1.2 cm, then drop 10 μLAPS solution, and then cover it with another electrode. After complete gelation, an in-situ assembled zinc battery is obtained.

[0042] Example 5 This embodiment prepares a hydrogel electrolyte (ZCHE) and a zinc battery. The specific process is as follows: (1) Weigh 2.39 g, 4.78 g, 9.56 g, 14.34 g, and 23.9 g of Zn(BF4)2 respectively and add them to 10 mL of deionized water and an organic mixture of ethylene glycol, sorbitol, glycerol, or dimethyl sulfoxide (1:1 / v:v), and stir at the same time to obtain 1 M, 2 M, 4 M, 6 M, and 10 M Zn(BF4)2 solutions respectively; (2) Mix 1 g AM, 1 g AA, 0.5 g AM and 0.5 g AA, 0.5 g AM and 0.5 g SBMA or 0.5 g AA and 0.5 g SBMA with 10 mg MBA and add to the above solution while stirring to obtain the precursor electrolyte solution; (3) Add 10 mg APS to 2 mL of deionized water while stirring to obtain a 5 mg / mL APS solution; (4) Take 0.2 mL of electrolyte precursor solution, drop it onto the surface of an electrode with a diameter of 1.2 cm, then drop 10 μLAPS solution, and then cover it with another electrode. After complete gelation, an in-situ assembled zinc battery is obtained.

[0043] Comparative Example 1 This comparative example prepares an electrolyte, and the specific process is as follows: (1) Prepare different concentrations of 1M or 2M ZnSO4, 1M-10M ZnCl2, 1M Zn(OTf)2, 1M LiBF4, and 1M Cu(BF4)2 respectively; (2) Mix 1 g AM, 1 g AA, 0.5 g AM and 0.5 g AA, 0.5 g AM and 0.5 g SBMA or 0.5 g AA and 0.5 g SBMA with 10 mg MBA and add them to the above solutions while stirring to obtain the precursor electrolyte solution. (3) Add 10 mg APS to 2 mL of deionized water and stir to obtain a 5 mg / mL APS solution; (4) Take 0.2 mL of electrolyte precursor solution and add 10 μL of APS solution. It cannot form a gel, so the battery cannot be assembled in situ.

[0044] Comparative Example 2 This comparative example demonstrates the preparation of a battery, and the specific process is as follows: (1) Weigh 9.56 g Zn(BF4)2 and add it to 10 mL of deionized water while stirring to obtain a 4 M Zn(BF4)2 solution (ZE-based). (2) Take 0.2 mL of 4 M Zn(BF4)2 solution and drop it into the glass fiber membrane to assemble the 2032 type coin cell into a symmetrical and a full cell.

[0045] Experimental Example 1 The equipment used for material characterization is as follows: 1. DSC: DSC 3; 2. Atomic Force Microscopy (AFM): Bruker Dimension icon; 3. Gas chromatography (GC): Zhongjiao Jinyuan GC7920; 4. Time-of-flight secondary ion mass spectrometry (TOF-SIMS): Nano TOF-2 instrument (ULVACPHI, Japan); 5. XPS: PHI 5000 VersaProbe II instrument, etching time 7 min.

[0046] Figure 2 The figures show the DSC curve (a), AFM image (b), and quantification results (c) of the ZCHE prepared in Example 1. It can be seen from the figures that the solidification point of 4M ZCHE is approximately -47.5 °C, and the interfacial adhesion is relatively high at approximately 40 J / m. -2 And a low interfacial impedance of approximately 30 Ω cm -2 .

[0047] Figure 3 The in-situ GC (a) and corresponding Arrhenius curve and activation energy (b) of the ZCHE prepared in Example 1 are shown in the figure. It can be seen from the figure that ZCHE can effectively suppress hydrogen evolution and has a low activation energy of 51.5 kJ mol. -1 This demonstrates that desolvation is easier in ZCHE.

[0048] Figure 4 The TOF-SIMS image (a) and XPS deep profile (b) of the ZCHE in-situ formed SEI layer obtained in Example 1 of this embodiment show that the layer is rich in CN. - Organic polymers dominate the zinc surface layer and are also rich in ZnO. - and ZnF - Inorganic species.

[0049] Experimental Example 2 Performance testing of in-situ assembled zinc batteries: I. Assembly and Performance Testing of Symmetrical Cells: The in-situ assembled Zn|ZCHE(ZE)|Zn(Cu) was assembled into 2032 coin cells. The symmetric cells were subjected to cycle performance tests at 25 ℃, -20 ℃, and -40 ℃, with a current density of 1 mA / cm². 2 Specific capacity is 1 mAh / cm³ 2 (0.5 mAh / cm) 2 ).

[0050] II. Assembly and Performance Testing of the Full Cell: The in-situ assembled Zn|ZCHE|I2 was assembled into a 2032 coin cell. The full cell was subjected to cycle performance testing at 25 ℃, -20 ℃, and -40 ℃, with a current density of 5 C (1 C = 211 mAg). -1 (vs. I2), testing the specific capacity of the battery.

[0051] Figure 5 The ZCHE-based Zn||Zn symmetric cells prepared in Example 1 and the ZE-based Zn||Zn symmetric cells prepared in Comparative Example 2 were compared at different current densities ( Figure 5 (a in the above figure) and different temperatures ( Figure 5 The charge-discharge cycle curves and the coulombic efficiency comparison of Zn||Cu batteries under the test conditions (see the figure below for 'a' in the figure). Figure 5 (b) The figure shows that the ZE-based symmetric cell short-circuited after nearly 180 hours of cycling, and the zinc-copper cell failed quickly; while the ZCHE-based symmetric cell could cycle stably for over 5200 hours, even at -20°C and -40°C for over 2200 hours and 600 hours respectively, and the zinc-copper cell could cycle 1500 times with a coulombic efficiency of up to 99.75%. This proves that ZCHE greatly improves the reversibility of the zinc anode. A cell that had undergone 20 cycles in this embodiment was disassembled, and its surface was characterized and analyzed by SEM and AFM. The results are as follows: Figure 6 As shown, the ZCHE-protected zinc anode surface is smooth with no dendrite formation and a low roughness of approximately 31.5 nm, while the unprotected zinc anode, after cycling, has loosely distributed dendrites and a high roughness of approximately 91.6 nm. This demonstrates that ZCHE can induce uniform zinc ion deposition and inhibit dendrite growth.

[0052] Figure 7 The ZCHE-based Zn||I2 full cell prepared for Example 1 was tested at 5 C (1 C = 211 mA g). -1The graph shows the cycling curves under different temperature test conditions (based on the mass of iodine). As can be seen from the graph, the ZCHE-based Zn||I₂ full cell can stably cycle for approximately 25,000 cycles at room temperature, with a coulombic efficiency as high as 99.9%. Even at -20 °C and -40 °C, it can still stably cycle for over 17,500 cycles and 1,000 cycles respectively. This demonstrates that the ZCHE-based full cell can operate stably at low temperatures.

[0053] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A hydrogel electrolyte, characterized in that: This includes polymer networks formed by crosslinking vinyl monomers with crosslinking agents and initiators, and the zinc tetrafluoroborate contained therein.

2. The hydrogel electrolyte according to claim 1, characterized in that: The mass ratio of the vinyl monomer to the crosslinking agent is 1:(50-150).

3. The hydrogel electrolyte according to claim 1, characterized in that: The mass ratio of zinc tetrafluoroborate to vinyl monomer is (2-50):

1.

4. The hydrogel electrolyte according to claim 1, characterized in that: The vinyl monomer includes at least one of acrylamide, N,N-dimethylacrylamide, N-isopropylacrylamide, acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and sulfobetaine methacrylate.

5. The hydrogel electrolyte according to claim 1, characterized in that: The crosslinking agent includes at least one of N,N-methylenebisacrylamide, glutaraldehyde, and polyethylene glycol diacrylate.

6. The hydrogel electrolyte according to claim 1, characterized in that: The initiator includes at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

7. A method for preparing the hydrogel electrolyte according to any one of claims 1-6, characterized in that: Includes the following steps: The hydrogel electrolyte is prepared by mixing zinc tetrafluoroborate, vinyl monomer and crosslinking agent, and then adding initiator to react.

8. The method for preparing hydrogel electrolyte according to claim 7, characterized in that: The reaction temperature is -50℃ to 30℃; and / or the reaction time is 30s to 120s.

9. A zinc battery, characterized in that: The hydrogel electrolyte comprising a positive electrode, a negative electrode, and a portion thereof disposed between the positive and negative electrodes, as described in any one of claims 1-6.

10. A method for preparing a zinc battery according to claim 9, characterized in that: Includes the following steps: Zinc tetrafluoroborate, vinyl monomers, and crosslinking agents are mixed to obtain a precursor solution. The precursor solution is coated onto an electrode, an initiator is added, another electrode is placed, and after reaction, the zinc battery is obtained.

Images