Preparation method of supramolecular gel electrolyte

Abstract

The invention relates to the technical field of polymer photoelectric materials, in particular to a preparation method of a supramolecular gel electrolyte. The method comprises the following steps: esterifying tetraphenylethylene alcohol and methacryloyl chloride to form tetraphenylethylene methacrylate, and performing staged linear heating polymerization on the tetraphenylethylene methacrylate, 3-(methacrylamido) propyl dimethyl 3-thiopropyl ammonium oxide inner salt, acrylic acid, tetraphenylethylene methacrylate and 4-vinylpyridine under the action of ammonium persulfate to obtain a tetraphenylethylene copolymer. And finally, soaking in a lithium chloride aqueous solution to obtain the supramolecular hydrogel electrolyte. The hydrogel obtained by the invention has high mechanical strength and high ionic conductivity, and is suitable for energy storage devices such as flexible supercapacitors and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer optoelectronic materials technology, specifically to a method for preparing a supramolecular gel electrolyte. Background Technology

[0002] Supramolecular hydrogel electrolytes, due to their dynamically reversible non-covalent cross-linked networks (such as hydrogen bonds, π-π stacking, and electrostatic interactions), show broad application prospects in flexible electronics and energy storage devices. However, the mechanical strength and ionic conductivity of traditional hydrogels often exhibit a contradictory relationship: hydrogels relying solely on hydrogen bonds or ionic cross-links, while flexible, are prone to stress relaxation at high water content, leading to insufficient compressive modulus (typically <0.3 MPa); while introducing covalent cross-links (such as chemical cross-linking agents) can enhance rigidity, it sacrifices dynamic reversibility, making the material brittle (elongation at break <150%), and the dense network hinders ion migration (conductivity <10). -3 S / cm); in addition, high ionic conductivity (>10). -2 The S / cm ratio relies on continuous hydration channels, but excessive hydration channels can weaken mechanical properties.

[0003] Currently, inorganic fillers are commonly used to improve the mechanical strength of hydrogels. However, defects at the filler-matrix interface can easily lead to stress concentration, and heterogeneous structures may block ion transport paths, adversely affecting ion migration. At the same time, conventional isothermal polymerization can easily cause uneven cross-linking, with local over-cross-linked areas forming "hard spots," while weakly cross-linked areas become mechanical bottlenecks. In addition, the uneven structure hinders ion diffusion.

[0004] Therefore, how to construct a supramolecular network with both high modulus and high extensibility without sacrificing ion migration channels has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a method for preparing supramolecular hydrogel electrolytes, so as to solve the problem that traditional supramolecular hydrogel electrolytes cannot simultaneously possess high mechanical strength and high ionic conductivity.

[0006] To achieve the above objectives, the present invention provides a method for preparing supramolecular gel electrolytes, comprising the following steps: S1: Tetraphenyl alcohol and methacryloyl chloride react at 25°C for 7-10 h in the presence of triethylamine to produce tetraphenyl methacrylate; S2: Dissolve 3-(methacryloylamino)propyldimethyl3-thiopropylammonium oxide inner salt, acrylic acid, tetraphenyl methacrylate and 4-vinylpyridine in deionized water and stir magnetically at 200-220 rpm until a clear and homogeneous solution is formed. S3: Under a nitrogen atmosphere, ammonium persulfate is added to the solution obtained in S2, and polymerized at 55-65℃ through a stepwise linear heating method to form a supramolecular hydrogel. Then, it is soaked in lithium chloride aqueous solution to form a supramolecular hydrogel electrolyte. The linear heating method for each stage is as follows: 55-58℃, heating rate is 1.5℃ / h; 58-63℃, heating rate is 1.7℃ / h; 63-65℃, heating rate is 0.7℃ / h.

[0007] Preferably, the amounts of tetrastyrene alcohol, methacrylamide chloride, and triethylamine used in step S1 are 0.7-1.3g, 0.2-0.4mL, and 0.4-0.6mL, respectively.

[0008] Preferably, in step S2, the amounts of 3-(methacryloylamino)propyldimethyl3-thiopropylammonium oxide inner salt, acrylic acid, tetraphenyl methacrylate, 4-vinylpyridine, and deionized water are 0.8-1.2g, 0.8-1.2g, 0.8-1.2g, 0.8-1.2g, and 2-3mL, respectively.

[0009] Preferably, the amount of ammonium persulfate used in step S3 is 0.006-0.01g.

[0010] Preferably, the molar concentration of the lithium chloride aqueous solution in step S3 is 0.3-0.7M.

[0011] Preferably, in step S2, during the initial stage of polymerization, acrylic acid and the inner salt monomer undergo free radical addition to form a copolymer backbone, while multiple hydrogen bonds are formed between the carboxyl group and the amide hydrogen, constructing a prototype topological hydrogen bond network. As the polymerization reaction continues to the middle stage, the hydrogen bond network further develops, and the π-π stacks between tetraphenyl methacrylate and 4-vinylpyridine tend to align parallelly, forming a layered orientation structure. The hydrogen bond network provides the internal stress driving the rigid-flexible transformation, prompting the π-π stacks to reorient, changing from a disordered slip state to a parallel overlapping mode. During the final stage of polymerization... During polymerization, the amide and carboxyl groups after free radical chain severance form new hydrogen bonds through electrostatic attraction, resulting in a new "aromatic ring core-hydrogen bond shell" bilayer structure in the network. The hydrogen bond regions enclose π-π stacked domains to form a topological flexible shell. After polymerization, the hydrogel is immersed in lithium chloride aqueous solution. Through the dual effects of ion exchange and swelling, the network is promoted to integrate again. The O atoms of Li⁺ and carboxyl groups coordinate to replace some hydrogen bond sites. The network electric field gradient causes the π–π stacked layers to rebalance and reorient, forming a bicontinuous structure. Finally, a supramolecular hydrogel electrolyte with high strength and high conductivity is formed.

[0012] The beneficial effects of this invention are: This invention solves the problem of synergistic optimization of mechanical strength and ionic conductivity through a gradient-temperature-induced hydrogen bond-π-π alternating assembly strategy. First, a rigid aromatic core-flexible hydrogen bond shell bicontinuous structure is formed through the synergistic effect of tetraphenylethylene methacrylate and 4-vinylpyridine and the encapsulation effect of the dynamic hydrogen bond network (carboxyl-amide hydrogen bonds); Secondly, by controlling the timing of gradient heating, the generation rate of hydrogen bonds and π-π stacking can be precisely controlled to avoid premature solidification of hydrogen bonds, ensuring that aromatic rings are arranged in an orderly manner and forming a uniform topological structure. Furthermore, a continuous conductive pathway is constructed in the hydrogen bond network through the synergistic conductivity mechanism of zwitterionic internal salt and lithium carboxylate; at the same time, the secondary regulation of lithium chloride swelling not only avoids mechanical degradation caused by excessive swelling, but also enhances the charge delocalization effect by optimizing the π-π stacking orientation through electric field gradient.

[0013] This invention achieves a breakthrough in both mechanical properties and ion transport performance in supramolecular hydrogels for the first time through the synergy of molecular design (tetraphenyl methacrylate / 4-vinylpyridine) and process innovation (gradient temperature rise), providing an ideal electrolyte material for high-performance flexible energy storage devices. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0015] Example 1: A method for preparing a supramolecular gel electrolyte, the specific steps of which are as follows: (1) Dissolve 0.7g of tetraphenylethylene alcohol in 15-30mL of anhydrous tetrahydrofuran, add 0.4mL of triethylamine, stir for 5min under nitrogen protection, and slowly add 0.2mL of methacryloyl chloride. React at 25℃ for 7h. After the reaction is complete, filter to remove the solvent and elute with ethyl acetate and petroleum ether in a volume ratio of 1:3 using a silica gel column to obtain tetraphenylethylene methacrylate. (2) Take a beaker, add 2 mL of deionized water, and weigh 0.8 g of 3-(methacryloylamino)propyldimethyl3-thiopropylammonium oxide inner salt, 0.8 g of acrylic acid, 0.15 g of tetraphenyl methacrylate and 0.15 g of 4-vinylpyridine in sequence. Stir magnetically at 200 rpm until a transparent and homogeneous solution is formed. (3) Place the solution obtained in step (2) under a nitrogen atmosphere, weigh 0.006 g of ammonium persulfate and add it to the solution and stir to dissolve. Pour the mixed solution into a glass mold with a thickness of 2 mm, heat it to 55 °C to start polymerization, and heat it to 58 °C at a heating rate of 1.5 °C / h, then heat it to 63 °C at a heating rate of 1.7 °C / h, and finally heat it to 65 °C at a heating rate of 0.7 °C / h. After the polymerization is completed, place the obtained hydrogel sample in a 0.3 M lithium chloride aqueous solution for 24 h to form a supramolecular hydrogel electrolyte.

[0016] Example 2: A method for preparing a supramolecular gel electrolyte, the specific steps of which are as follows: (1) Dissolve 1g of tetrastyrene alcohol in 20mL of anhydrous tetrahydrofuran, add 0.5mL of triethylamine, stir for 8min under nitrogen protection, and slowly add 0.3mL of methacryloyl chloride. React at 25℃ for 9h. After the reaction is completed, filter to remove the solvent and elute with ethyl acetate and petroleum ether in a volume ratio of 1:3 using a silica gel column to obtain tetrastyrene methacrylate. (2) Take a beaker, add 2.5 mL of deionized water, and weigh 1 g of 3-(methacryloylamino)propyldimethyl3-thiopropylammonium oxide inner salt, 1 g of acrylic acid, 0.2 g of tetraphenyl methacrylate and 0.2 g of 4-vinylpyridine in sequence. Stir magnetically at 210 rpm until a transparent and homogeneous solution is formed. (3) Place the solution obtained in step (2) under a nitrogen atmosphere, weigh 0.008 g of ammonium persulfate and add it to the solution and stir to dissolve. Pour the mixed solution into a glass mold with a thickness of 2 mm, heat it to 55 °C to start polymerization, and heat it to 58 °C at a heating rate of 1.5 °C / h, then heat it to 63 °C at a heating rate of 1.7 °C / h, and finally heat it to 65 °C at a heating rate of 0.7 °C / h. After the polymerization is completed, place the obtained hydrogel sample in 0.5 M lithium chloride aqueous solution for 24 h to form supramolecular hydrogel electrolyte.

[0017] Example 3: A method for preparing a supramolecular gel electrolyte, the specific steps of which are as follows: (1) Dissolve 1.3g of tetraphenylethylene alcohol in 30mL of anhydrous tetrahydrofuran, add 0.6mL of triethylamine, stir for 10min under nitrogen protection, and slowly add 0.4mL of methacryloyl chloride. React at 25℃ for 10h. After the reaction is completed, filter to remove the solvent and elute with ethyl acetate and petroleum ether in a volume ratio of 1:3 using a silica gel column to obtain tetraphenylethylene methacrylate. (2) Take a beaker, add 3 mL of deionized water, and weigh 1.2 g of 3-(methacryloylamino)propyldimethyl3-thiopropylammonium oxide inner salt, 1.2 g of acrylic acid, 0.25 g of tetraphenyl methacrylate and 0.25 g of 4-vinylpyridine in sequence. Stir magnetically at 220 rpm until a transparent and homogeneous solution is formed. (3) Place the solution obtained in step (2) under a nitrogen atmosphere, weigh 0.01 g of ammonium persulfate and add it to the solution and stir to dissolve. Pour the mixed solution into a glass mold with a thickness of 2 mm, heat it to 55 °C to start polymerization, and heat it to 58 °C at a heating rate of 1.5 °C / h, then heat it to 63 °C at a heating rate of 1.7 °C / h, and finally heat it to 65 °C at a heating rate of 0.7 °C / h. After the polymerization is completed, place the obtained hydrogel sample in a 0.7 M lithium chloride aqueous solution for 24 h to form a supramolecular hydrogel electrolyte.

[0018] Comparative Example 1: The difference from Example 2 is that tetraphenyl methacrylate is not added in step (2), and the other steps are the same as in Example 2.

[0019] Comparative Example 2: The difference from Example 2 is that tetraphenyl methacrylate and 4-vinylpyridine are not added in step (2), and the rest of the steps are the same as in Example 2.

[0020] Comparative Example 3: The difference from Example 2 is that in step (2), 3-(methacryloylamino)propyldimethyl3-thiopropylammonium oxide inner salt and acrylic acid are replaced with 1.82g of styrene, and the remaining steps are the same as in Example 2.

[0021] Comparative Example 4: The difference from Example 2 is that the polymerization reaction conditions in step (3) are 60°C for 8 hours.

[0022] Performance testing Mechanical performance testing: The compression and tensile properties of the samples from Examples 1-3 and Comparative Examples 1-4 were tested using an electronic universal testing machine (CMT4204). The samples were prepared as cylindrical specimens (compression) with a diameter of 10 mm and a height of 5 mm and dumbbell-shaped specimens (tensile). The test rates were 1 mm / min and 50 mm / min, respectively. Ionic conductivity test: According to ASTM D7148-13 standard, it was measured by AC impedance method using an electrochemical workstation (CHI760E model) (frequency range 0.1Hz-1MHz, amplitude 10mV); A flexible supercapacitor was fabricated by attaching PEDOT:PSS electrodes to both sides of a supramolecular hydrogel electrolyte film, and its electrochemical performance was tested according to the GB / T 30836-2014 supercapacitor testing standard. The test results are shown in Table 1. Table 1 Performance Test Results Compression modulus (MPa) Elongation at break (%) Ionic conductivity (S / cm) Capacitance retention rate (5000 cycles) Example 1 0.38 322 <![CDATA[1.8×10 -2 ]]> 90.2 Example 2 0.42 350 <![CDATA[2.1×10 -2 ]]> 92.4 Example 3 0.40 345 <![CDATA[2.0×10 -2 ]]> 91.1 Comparative Example 1 0.25 188 <![CDATA[1.9×10 -2 ]]> 85.7 Comparative Example 2 0.22 155 <![CDATA[4.3×10 -3 ]]> 73.3 Comparative Example 3 0.38 105 <![CDATA[5.0×10 -3 ]]> 60.9 Comparative Example 4 0.30 222 <![CDATA[1.2×10 -2 ]]> 80.1 Data Analysis: Data from Examples 1-3 in Table 1 shows that a supramolecular network with both high mechanical strength and ionic conductivity is formed through the synergistic effect of tetraphenylethylene methacrylate and 4-vinylpyridine. The principle behind this may be that the alternating hydrogen-bonding π-π assembly induced by gradient heating during polymerization constructs a bicontinuous structure of a "rigid aromatic core-flexible hydrogen-bonded shell." The aromatic ring stacking domains (π-π interactions) provide mechanical support, while the dynamic hydrogen bond network dissipates stress through reversible breakage and recombination, while retaining ion migration channels. Furthermore, the stability of the capacitance retention rate further verifies the durability of this structure, presumably due to the optimized coordination of lithium chloride with carboxyl groups after swelling, which reduces structural degradation during cycling.

[0023] From the data in Table 1 of Example 2 and Comparative Example 1, it can be inferred that the introduction of tetraphenyl methacrylate promotes the directional arrangement of π-π stacked domains, and its rigid aromatic core enhances the material's resistance to deformation. At the same time, the flexible buffering effect of the hydrogen bond network avoids the blockage of ion pathways by densification, and the charge delocalization effect of π-π stacking stabilizes the charge transport at the electrode-electrolyte interface, ensuring the retention rate of capacitance.

[0024] From the data in Table 1 of Example 2 and Comparative Example 2, it can be inferred that the aromatic ring stacking of tetraphenyl methacrylate and the π–π interaction of 4-vinylpyridine jointly construct a long-range ordered framework. The topological flexibility of the hydrogen bond network and the retention of ion-conducting groups (internal salt, lithium carboxylate) depend on the support of this framework. Furthermore, the decrease in capacitance retention (73.3% vs 92.4%) further reflects that the disordered structure exacerbates the ion migration resistance during the cycling process.

[0025] As can be clearly seen from the data in Table 1 of Example 2 and Comparative Example 3, the elongation at break and ionic conductivity of Comparative Example 3 are significantly reduced, but its compressive modulus is close to that of Example 2. However, the high modulus accompanied by low ductility indicates increased network brittleness. This may be because the lack of dynamic crosslinking of carboxyl / amide hydrogen bonds in the homopolymer chain of styrene leads to stress concentration, and the absence of ionic conductive groups directly hinders charge transport.

[0026] From the data in Table 1 of Example 2 and Comparative Example 4, it can be inferred that gradient heating is crucial for the alternating hydrogen bond-π-π assembly. Uniform heating may cause the hydrogen bond network to solidify prematurely, inhibiting the directional rearrangement of aromatic rings and reducing network uniformity. In contrast, staged heating, by controlling the free radical reaction rate, achieves the stepwise optimization of dynamic crosslinking, and the difference in capacitance retention further indicates that the hierarchical structure formed by gradient heating is more resistant to volume changes during charging and discharging.

[0027] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a supramolecular gel electrolyte, characterized in that, Includes the following steps: S1: Tetraphenylene alcohol and methacryloyl chloride undergo esterification in the presence of triethylamine to produce tetraphenylene methacrylate; S2: Add 3-(methacryloylamino)propyldimethyl3-thiopropylammonium oxide inner salt, acrylic acid, tetraphenyl methacrylate and 4-vinylpyridine to deionized water to form a transparent and homogeneous solution; S3: Under a nitrogen atmosphere, ammonium persulfate is added to the solution obtained in S2 and polymerized at 55-65℃ through a stepwise linear heating method to form a supramolecular hydrogel. Then, it is soaked in lithium chloride aqueous solution to form a supramolecular hydrogel electrolyte. The linear heating method for each stage is as follows: 55-58℃, heating rate is 1.5℃ / h; 58-63℃, heating rate is 1.7℃ / h; 63-65℃, heating rate is 0.7℃ / h.

2. The preparation method according to claim 1, characterized in that, In step S1, the amounts of tetraphenylethylene alcohol, methacrylamide chloride, and triethylamine used are 0.7-1.3g, 0.2-0.4mL, and 0.4-0.6mL, respectively.

3. The preparation method according to claim 1, characterized in that, The esterification reaction in step S1 is carried out at 25°C for 7-10 hours.

4. The preparation method according to claim 1, characterized in that, In step S2, the amounts of 3-(methacryloylamino)propyldimethyl3-thiopropylammonium oxide inner salt, acrylic acid, tetraphenyl methacrylate, 4-vinylpyridine, and deionized water are 0.8-1.2g, 0.8-1.2g, 0.8-1.2g, 0.8-1.2g, and 2-3mL, respectively.

5. The preparation method according to claim 1, characterized in that, The amount of ammonium persulfate used in step S3 is 0.006-0.01g.

6. The preparation method according to claim 1, characterized in that, The molar concentration of the lithium chloride aqueous solution in step S3 is 0.3-0.7M.

7. The preparation method according to claim 1, characterized in that, The polymerization conditions described in step S3 are polymerization at 55-65℃ for 8-10 hours.

8. The preparation method according to claim 1, characterized in that, The soaking time in step S3 is 24 hours.