Preparation and use of monoprotic conductive, freeze resistant organic hydrogel electrolytes

Abstract

The application belongs to the field of new materials, and relates to surface functional material research, in particular to preparation, properties and application of single-proton conductive anti-freezing organic hydrogel. The preparation method of the polyAH-E hydrogel is as follows: a hydrophilic monomer acrylamide (AM) and an anionic monomer 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) are randomly copolymerized in a mixed solution of ethylene glycol (EG) and water to obtain the polyAH-E hydrogel. The molar ratio of the AM and AMPS monomers is (6:1) to (1:6), and the volume concentration of the ethylene glycol in the mixed solution of the ethylene glycol (EG) and water is 0% to 70%. The preparation method is simple and low in cost. The obtained polyAH-E electrolyte has excellent low-temperature performance and strong plasticity.

Description

Technical Field

[0001] This invention belongs to the field of new materials and relates to the research of surface functional materials, specifically to the preparation, properties and applications of antifreeze organic hydrogels with single-proton conductivity. Background Technology

[0002] With rapid societal development, global demand for new technologies and new energy sources is increasing rapidly, prompting the emergence of new materials and energy storage devices. Miniaturized and portable flexible wearable electronic devices have experienced explosive growth. Among them, flexible supercapacitors (SCs), as electronic energy storage devices, have attracted much attention due to their advantages such as light weight, high power density, rapid charging and discharging capabilities, and mechanical flexibility. Hydrogels are widely considered ideal materials for flexible (SCs) due to their inherent conductivity, good mechanical properties, and biocompatibility. However, the large amount of water in traditional hydrogel electrolytes inevitably freezes below 0°C, leading to a significant reduction or even loss of the electrolyte's ionic conductivity and mechanical flexibility. This severely limits the application of SCs at low temperatures.

[0003] Numerous reports have been published on solutions to the freezing problem of hydrogels at low temperatures. For example, Suo et al. were able to lower the freezing point of a hydrogel system to -57°C using 30 wt% CaCl2, while 10 wt% CaCl2 could only lower it to -7°C (XPMorelle, WRIlleperuma, K.Tian, ​​R.Bai, Z.Suo, JJVlassak, Adv. Mater. 2018, 30, 1801541). Wang et al. prepared an antifreeze hydrogel using 3M LiTFSI with a conductivity of only 0.1 mS cm⁻¹ at -40°C (ChemSusChem 2021, 14, 2056–2066). However, introducing large amounts of inorganic salts inevitably increases costs, and excessively high salt concentrations can corrode energy storage devices, posing safety hazards.

[0004] CN202110814384.0 discloses a polyelectrolyte hydrogel coating with superior substrate adhesion and its preparation method. The preparation method includes the following steps: 1) activating the substrate using oxygen plasma; 2) dissolving a polycationic polymer, polymeric monomers, a siloxane crosslinking agent, and an initiator to obtain a prepolymer solution, removing air bubbles by vacuuming, and then coating it onto the oxygen plasma-activated substrate surface. In-situ polymerization is then performed under a nitrogen or rare gas atmosphere, followed by curing. The polymeric monomers include at least one of acrylamide, acrylic acid, methacrylic acid hydroxyethyl ester, 2-acryloylamino-2-methyl-1-propanesulfonic acid, polyethylene glycol (diol) diacrylate, 2-methacryloyloxyethyl phosphocholine, methacryloylethyl sulfobetaine, and 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate; the siloxane crosslinking agent has a carbon-carbon double bond functional group. However, the process is very complex, costly, and cannot achieve good antifreeze effects at low temperatures. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing PolyAH-E hydrogel electrolytes and their application as single-electron conductive antifreeze hydrogel electrolytes. This preparation method is simple and can produce a series of antifreeze hydrogel electrolytes. These antifreeze hydrogel electrolytes still exhibit high conductivity, excellent tensile strain, and tensile stress at low temperatures.

[0006] This invention is achieved through the following technical solutions:

[0007] A method for preparing PolyAH-E hydrogel, characterized in that: hydrophilic monomer acrylamide (AM) and anionic monomer 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) are randomly copolymerized in a mixed solution of ethylene glycol (EG) and water. The molar ratio of AM to AMPS monomers is (6:1) to (1:6), and the volume concentration of ethylene glycol in the mixed solution of ethylene glycol (EG) and water is 0% to 70%.

[0008] A method for preparing a PolyAH-E hydrogel electrolyte includes the following steps:

[0009] S1, AM and AMPS monomers are dissolved in an aqueous ethylene glycol solution.

[0010] S2, place the solution obtained in S1 in an ice bath and stir for 0.5–1.5 h until all monomers are dissolved.

[0011] S3. Add the initiator to the solution obtained in S2, stir in an ice bath for 20-40 minutes, and sonicate for 5-15 minutes to remove air bubbles to obtain the precursor solution.

[0012] S4. Inject the precursor solution into the mold, seal it, and polymerize it in an environment of 30-50°C for 8-16 hours.

[0013] The resulting hydrogel is abbreviated as polyAxHy-Ez, where x and y are the molar ratios of AM and AMPS, respectively, and z is the volume concentration of EG.

[0014] Preferably, in step S1, the molar ratio of AM and AMPS monomers is (6:1) to (1:6), and the volume concentration of ethylene glycol in the mixed solution of ethylene glycol (EG) and water is 0% to 70%. The ratio of monomer mass to mixed solution volume is 1:2 to 1:4. Dissolving AM and AMPS monomers separately before mixing, or mixing AM and AMPS monomers first before adding them to the solvent, will not affect the result because both monomers are hydrophilic and will not affect the solubility of the other monomer. Furthermore, no initiator is added in this step, preventing premature reaction. Preferably, the volume concentration of ethylene glycol in the mixed solution of ethylene glycol (EG) and water is 10% to 70%; more preferably, the volume concentration of ethylene glycol in the mixed solution of ethylene glycol (EG) and water is 30% to 70%.

[0015] Preferably, in step S2, the solution obtained in S1 is placed in an ice bath and stirred for 0.8 to 1.2 hours.

[0016] Preferably, in step S3, the initiator is APS, and the amount of initiator added is 0.5 to 1.5 wt% of the monomer mass; more preferably, the amount of initiator added is 1 wt% of the monomer mass.

[0017] The present invention also provides a hydrogel electrolyte obtained by the above method, wherein the freezing point of the hydrogel electrolyte is below -21.62°C.

[0018] Preferably, when the AM:AMPS ratio is (6:1) to (1:6), the ionic conductivity of the polyAH hydrogel electrolyte is 82.89 to 230.09 mS / cm. -1 Preferably, when the AM:AMPS ratio is 3:1 to 1:3, the ionic conductivity of the polyAH hydrogel electrolyte is 137.81 to 211.94 mS / cm. -1 .

[0019] When the AM:AMPS ratio is 3:1 to 1:3 and the EG volume ratio is 0, the stress of the polyAH hydrogel electrolyte is 48.9 to 11.3 kPa and the strain is 376.36% to 480.02%.

[0020] Preferably, at room temperature, when the EG volume ratio is 30% to 70%, the stress of the polyAH hydrogel electrolyte is 37.3 to 11.7 kPa and the strain is 728.92% to 1772.72%.

[0021] Preferably, at -40°C, when the EG volume ratio is 30%–70%, the ionic conductivity of the polyAH hydrogel electrolyte is 0.55–1.28 mS / cm. -1 .

[0022] After 8 days, the water retention capacity of polyAH electrolyte with an ethylene glycol content of 30%–70% is 50%–90%.

[0023] The present invention also provides the use of the hydrogel electrolyte obtained by the above method in supercapacitors (SC).

[0024] The present invention has the following beneficial effects:

[0025] A series of antifreeze hydrogel electrolytes (polyAH-E electrolytes) were prepared by dissolving the hydrophilic monomer acrylamide (AM) and the anionic monomer 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in a water / ethylene glycol binary solvent via a one-pot method. The preparation method is simple and low-cost. The polyAH-E electrolytes exhibit excellent low-temperature performance.

[0026] polyA3H1-E 50 The electrolyte exhibits exceptional plasticity and can be molded into various shapes to meet diverse needs. It also possesses remarkable water retention capabilities; after being placed in a dry environment for eight days, the electrolyte retains 78.94% of its initial mass.

[0027] By controlling the monomer ratio and EG content, it was found that when AM:AMPS = 3:1 and the EG content is 50 vol%, i.e., polyA3H1-E 50 The electrolyte exhibits optimal overall performance. At room temperature, polyA3H1-E... 50 The tensile strain and tensile stress of the electrolyte were 1058.6% and 28.6 kPa, respectively. (polyA3H1-E) 50 The electrolyte can still provide 1.28 mS cm⁻¹ at -40°C. -1 High ionic conductivity. Attached Figure Description

[0028] Figure 1 Schematic diagram of the preparation of antifreeze hydrogel;

[0029] Figure 2 Photographs of gels formed after polymerization of monomer combinations with different molar ratios;

[0030] Figure 3 Ionic conductivity of hydrogel electrolytes with different monomer molar ratios;

[0031] Figure 4 Stress-strain curves of hydrogel electrolytes with different monomer molar ratios;

[0032] Figure 5 Stress-strain curves of hydrogel electrolytes with different EG contents;

[0033] Figure 6 Temperature dependence of ionic conductivity of different electrolytes;

[0034] Figure 7 The electrostatic interactions (b) formed between the cations and anions (a) inside the electrolyte can be freely transported under the applied voltage;

[0035] Figure 8 polyA3H1-E0 and polyA3H1-E 50 Photographs of the electrolyte at room temperature and -40°C;

[0036] Figure 9 The relationship between the number of days of air exposure and sample mass loss;

[0037] Figure 10 DSC curves of hydrogel electrolytes with different EG contents;

[0038] Figure 11 SC images under an electron microscope;

[0039] Figure 12 Voltage window of the assembled SC;

[0040] Figure 13 CV curves of SC at different scan rates at (a) 25℃ and (c) 60℃; GCD curves of different current densities at (b) 25℃ and (d) 60℃;

[0041] Figure 14 CV, GCD, and EIS curves of SC at different temperatures;

[0042] Figure 15 SC at -40℃: (a) CV curves at different scan rates and (b) GCD curves at different current densities. Detailed Implementation

[0043] The following embodiments are further illustrations of the present invention, but the present invention is not limited thereto.

[0044] Raw materials and reagents

[0045] 2-Acryloylamino-2-methyl-1-propanesulfonic acid (C7H) 13NO4S), analytical grade, Aladdin Reagent Co., Ltd.; Acrylamide (C3H5NO), analytical grade, Aladdin Reagent Co., Ltd.; Ammonium persulfate ((NH4)2S2O8), analytical grade, Aladdin Reagent Co., Ltd.; N,N-methylenebisacrylamide (C7H 10 N2O2), analytical grade, Aladdin Reagent Co., Ltd.; ethylene glycol ((CH2OH)2), analytical grade, Sinopharm Chemical Reagent Co., Ltd.; polyvinylidene fluoride ([CH2CF2]n), analytical grade, Macklin Biotechnology Co., Ltd.; N-methylpyrrolidone (C5H9NO), analytical grade, Macklin Biotechnology Co., Ltd.; carbon cloth, W0S1011, CeTech Ltd.; activated carbon, YP-50F, Kuraray Ltd., Japan; carbon black, battery grade, AlfaAesar Ltd.

[0046] Experimental instruments and equipment

[0047] Constant temperature forced-air drying oven, DHG-9123A, Shanghai Yiheng Scientific Instrument Co., Ltd.; Ultrasonic cleaner, KQ3200B, Kunshan Ultrasonic Instrument Co., Ltd.; Microcomputer-controlled universal mechanical testing machine, WDW-02, Jinan Hengsishengda Instrument Co., Ltd.; Heat-collecting constant temperature magnetic stirrer, DF-101S, Henan Yuhua Instrument Co., Ltd.; Constant temperature and humidity test chamber, LS-TH-100S, Lais Testing Equipment Co., Ltd.; Differential scanning calorimeter, TAQ-10, TA Instruments, USA; Electrochemical workstation, CHI660E, Shanghai Chenhua Instrument Co., Ltd.; Laser confocal Raman spectrometer, Lab RAM H600, HORIBA JY, France.

[0048] Test characterization

[0049] Mechanical performance testing

[0050] Mechanical measurements were performed using a universal mechanical testing instrument (Hensgrand, WDW-02, China). Measurements were taken at 100 mm / min. -1 A cylinder with a diameter of 6 mm and a length of 40 mm is stretched at a certain tensile speed. Mechanical performance testing involves analyzing the median data from the dataset with the most frequent measurements.

[0051] Water retention test of organic hydrogel electrolyte

[0052] Take two pieces of polyA3H1-E0 and polyA3H1-E of the same mass 50 The gel electrolyte was exposed to air at room temperature, and its mass was recorded every 24 hours.

[0053] Electrochemical performance measurement of polyAH-E organic hydrogel electrolyte

[0054] The ionic conductivity (σ) of the hydrogel electrolyte was measured using a dual-probe method on a CHI 660E electrochemical workstation. The amphoteric hydrogel electrolyte was filled into a CR927 battery case and stabilized at different temperatures for 1–2 hours, after which the conductivity was measured at the corresponding temperatures. Each sample was measured 3–5 times, and the average value was taken. The ionic conductivity was calculated using a formula.

[0055]

[0056] Where R is the resistance (Ω) and S is the cross-sectional area (cm²) of the electrolyte being measured. 2 ), where L is the thickness (cm) of the sample being tested.

[0057] Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) measurements were performed using a two-electrode system on a CHI660E workstation. CV was performed at different scan rates between 0 and 1 V. EIS was performed at an amplitude of 10 mV between 0.01 Hz and 100 kHz. GCD was performed at different current densities between 0 and 1 V. The mass specific capacitance of a single electrode (Csp, F g) was measured. -1 The value is obtained from the discharge curve of GCD and calculated according to the following formula.

[0058]

[0059] Where I is the discharge current (mA), Δt is the discharge time (s), and m device Let denoted as the total mass (g) of the two electrodes of the supercapacitor, and ΔV represent the discharge voltage (V).

[0060] Other tests

[0061] Differential scanning calorimetry (DSC) was performed using a TA2500 instrument. The sample was first cooled from room temperature to -80°C, and then heated from -80°C to 60°C. Both cooling and heating rates were 15°C / min. -1 The sample mass was between 5-10 mg. The sample testing was conducted under nitrogen atmosphere protection.

[0062] Example 1: Preparation of PolyAH-E hydrogel

[0063] A series of polyAH-EG organic hydrogels were obtained by random copolymerization of AM and AMPS in a mixed solution of ethylene glycol (EG) and water. The preparation process of the polyAH-E hydrogels is as follows: Figure 1As shown in the diagram, firstly, AM and AMPS monomers (total mass 2.0 g) were dissolved in ethylene glycol aqueous solutions of different volume concentrations (4.0 mL). Then, the solution was placed in an ice bath and stirred for 1 h until all monomers were dissolved. Next, 0.02 g of initiator (APS, 1 wt% of monomer mass) was added to the homogeneous mixture, and the solution was stirred in an ice bath for 0.5 h, followed by ultrasonic agitation for 10 min to remove air bubbles. Subsequently, the precursor solution was injected into a mold, sealed, and polymerized at 40°C for 12 h. The resulting hydrogel is abbreviated as polyAxHy-Ez, where x and y are the molar ratios of AM and AMPS, respectively, and z is the volume concentration of EG.

[0064] Example 2

[0065] Everything else is the same as in Example 1, except that...

[0066] The EG concentration was set to 0, and the molar ratio of AM to AMPS was varied. Using AM:AMPS ratios of 6:1, 3:1, 1:1, 1:3, and 1:6, it was found that all monomer ratios exhibited good ability to form solid gels. Figure 2 As shown, hydrogels with different monomer ratios were polymerized at 40°C for 12 hours. Then, glass bottles containing hydrogels with different monomer ratios were inverted. Obviously, the polymerized hydrogels with different monomer ratios were all at the bottom of the bottle and did not flow down due to inversion. This shows that hydrogels with all monomer ratios were successfully polymerized and all exhibited good solid properties.

[0067] Acrylamide (AM) possesses both hydrogen bond donors and acceptors, and its polymerization conditions are simple, making it an excellent material for preparing hydrogels. 2-Acrylamido-2-methyl-1-propanesulfonic acid (AMPS) is a strong organic acid that can easily dissociate its protons; introducing AMPS into hydrogels can impart high ionic conductivity. In this work, we used the hydrophilic monomer AM and the anionic monomer AMPS to construct a hydrogel with high ionic conductivity. Ethylene glycol (EG) ensures the hydrogel's antifreeze properties; it is added before polymerization by pre-mixing with water. Subsequently, the antifreeze hydrogel polyAH-E was prepared using a one-pot method.

[0068] Example 3: Mechanical properties and ionic conductivity of the electrolyte

[0069] Ionic conductivity is one of the most essential and important indicators of electrolytes. By testing the conductivity of hydrogel electrolytes with different monomer ratios at room temperature, it was found that there are significant differences in conductivity among hydrogels with different monomer ratios. Figure 3As shown, the amount of AMPS, acting as the conductive medium in polyAH hydrogel electrolytes, directly determines the ionic conductivity of the polyAH hydrogel electrolyte. For example, the ionic conductivity of polyAlH6 hydrogel electrolytes with high AMPS content reaches as high as 230.09 mS / cm. -1 However, when the AMPS content was reduced to a molar ratio of 6:1 (AM:AMPS), the ionic conductivity of polyA6H1 plummeted to 82.89 mS / cm. -1 When the AM:AMPS ratio is (6:1) to (1:6), the ionic conductivity of the polyAH hydrogel electrolyte is 82.89–230.09 mS / cm. -1 Preferably, when the AM:AMPS ratio is 3:1 to 1:3, the ionic conductivity of the polyAH hydrogel electrolyte is 137.81 to 211.94 mS / cm. -1 .

[0070] Besides ionic conductivity, a crucial indicator, the mechanical flexibility of hydrogel electrolytes is also very important, as it is a necessary performance characteristic for novel flexible devices. The stress-strain curves of hydrogel electrolytes with different monomer ratios at room temperature are shown below. Figure 4 As shown, the modulus of polyA6H1 hydrogel electrolyte with high AM content is significantly higher than that of polyA1H6 hydrogel electrolyte with high AMPS content. However, the strain advantage brought by the high AMPS content to polyA6H1 hydrogel electrolyte is not significant. For example, the stress and strain of polyA6H1 hydrogel electrolyte are 305.71% and 60.1 kPa, respectively, while those of polyA1H6 hydrogel electrolyte are only 510.24% and 7.1 kPa. Preferably, when the AM:AMPS ratio is 3:1 to 1:3, the stress of polyA6H1 hydrogel electrolyte is 48.9 to 11.3 kPa, and the strain is 376.36% to 480.02%.

[0071] Example 4: Mechanical properties and ionic conductivity of antifreeze electrolyte

[0072] Considering ion conductivity and mechanical properties, an electrolyte with a molar ratio of AM:AMPS = 3:1 was ultimately selected. The antifreeze properties of the hydrogel electrolyte were studied by adding different volume ratios of EG.

[0073] Solving the freezing problem of hydrogels at low temperatures is crucial for expanding their operating temperature range. Ethylene glycol, rich in hydroxyl groups, has been widely used as an antifreeze agent. This has been studied in our previous work; adding EG to aqueous solutions disrupts the existing hydrogen bonding system between water molecules, thus inhibiting freezing. Here, we add different volume percentages of EG as antifreeze agents to prepare antifreeze hydrogels.

[0074] Traditional chemically cross-linked hydrogels suffer from insufficient mechanical flexibility due to the predominantly irreversible covalent bonds at their internal cross-linking points. The hydrogen bonds formed between EG and water are dynamically recoverable, which significantly improves the flexibility of the hydrogel electrolyte. The stress-strain curve of the hydrogel electrolyte at room temperature is shown below. Figure 5 As shown, the ductility of the hydrogel electrolyte increases significantly with increasing EG content. For example, the strain and stress of the polyA3H1-E0 electrolyte are 376.43% and 48.89 kPa, respectively; however, the ductility of the polyA3H1-E0 electrolyte is significantly higher. 70 The strain of the electrolyte increased to 1767.27%. On the other hand, the stress decreased to 11.91 kPa. Preferably, when the EG volume ratio is 30% to 70%, the stress of the polyAH hydrogel electrolyte is 37.3 to 11.7 kPa, and the strain is 728.92% to 1772.72%.

[0075] Therefore, this electrolyte has good plasticity, and its simple preparation process can easily produce gels with complex shapes, indicating that it has great potential and can be suitable for various application scenarios.

[0076] Table 1 Ionic conductivity at different temperatures and EG contents High ionic conductivity at low temperatures is equally important for the low-temperature applications of hydrogels. We then measured the conductivity of hydrogel electrolytes with different EG contents at different temperatures, and the results are as follows: Figure 6 As shown in Table 1, at low temperatures, the conductivity of the hydrogel electrolyte first increases and then decreases with increasing EG content. This is mainly because appropriate EG prevents water from freezing, but excessive EG is detrimental to ion transport; the highest ionic conductivity at -40℃ is 1.28 mS / cm. -1 , by polyA3H1-E 50 Electrolytes are provided. More importantly, the ionic conductivity of the electrolyte below 0°C exhibits a linear relationship with the reciprocal of the absolute temperature, obeying Arrhenius's law. polyA3H1-E 50 The activation energy of the electrolyte at low temperature is 0.307 eV, which is much lower than that of the polyA3H1-E0 electrolyte (0.938 eV). It is well known that when Ea is less than 0.4 eV, proton transport within the system follows the Grotthuss mechanism. A schematic diagram of ion transport within the hydrogel electrolyte after applying voltage is shown below. Figure 7 As shown. Preferably, at -40°C, when the EG volume ratio is 30%–70%, the ionic conductivity of the polyAH hydrogel electrolyte is 0.55–1.28 mS / cm. -1 .

[0077] Example 5: Antifreeze and water retention properties of polyAH-E electrolyte

[0078] The addition of ethylene glycol not only affects the mechanical properties and conductivity of hydrogels, but more directly affects their tolerance to extreme environments. Figure 8 PolyA3H1-E0 and PolyA3H1-E were demonstrated. 50 The low-temperature resistance of the electrolyte is as follows: the polyA3H1-E0 electrolyte freezes rapidly below 0°C and turns white. After freezing, the polyA3H1-E0 electrolyte becomes extremely brittle and almost loses all its properties (ionic conductivity is 0.13 mS / cm). -1 , Figure 6 Conversely, polyA3H1-E 50 Even after stabilizing at -40°C for 5 hours, the electrolyte remains transparent and exhibits excellent mechanical flexibility; the internal water molecules do not freeze due to the extreme low temperature. Furthermore, polyA3H1-E... 50 The electrolyte also exhibited excellent water retention capacity, such as... Figure 9 As shown. Two original polyA3H1-E0 electrolytes and polyA3H1-E electrolytes of equal mass were used. 50 Electrolytes exposed to air for 8 days, polyA3H1-E 50 The electrolyte still retained 78.94% of its water retention capacity, but after 24 hours, the polyA3H1-E0 electrolyte had almost completely lost all the water in the system. After 8 days, the polyAH electrolyte with an ethylene glycol content of 30%–70% retained 50%–90% of its water retention capacity.

[0079] Subsequently, differential scanning calorimetry (DSC) was used to observe the effect of different EG contents on the freezing point of the hydrogel electrolyte. Figure 10 As shown, when the EG content is 0 and 30 vol%, polyA3H1-E0 and polyA3H1-E 50 The freezing points of the electrolytes were 0℃ and -21.62℃, respectively. However, when the EG content increased to 50% and 70% vol%, no endothermic peaks were observed in the DSC curves, indicating that there was no change in heat flow due to freezing inside them.

[0080] EG, as a strongly hydrophilic molecule, forms hydrogen bonds upon contact with water molecules. These interactions disrupt the original three-dimensional hydrogen bond structure between water molecules, forming a new, more stable EG-H₂O hydrogen bond system. Simultaneously, this reduces the amount of free water in the solution. Therefore, polyA₃H₁-E 50 The electrolyte exhibited excellent antifreeze properties and good water retention.

[0081] Example 6: Applying antifreeze electrolyte to a supercapacitor (SC)

[0082] Assembly of organic hydrogel electrolyte-based supercapacitors (SC)

[0083] First, 80 mg of AC, 10 mg of conductive carbon black, and 10 mg of PVDF (polyvinylidene fluoride) were ground together, and an appropriate amount of NMP was added to form a uniform dispersion. This dispersion was then uniformly coated onto carbon cloth and placed in a vacuum furnace at 180°C for 24 hours to obtain the AC electrode. The mass of the active material on each electrode was recorded.

[0084] Two AC electrodes with the same mass of active material were used to cover both sides of a PolyAH-E hydrogel electrolyte to prepare a supercapacitor. In the PolyAH-E hydrogel electrolyte, AM:AMPS = 3:1, and the EG volume ratio was 50%.

[0085] A few drops of electrolyte precursor solution were then added to both electrodes of the capacitor to wet them. The total thickness of the prepared capacitor was approximately 0.9 mm, with the electrolyte layer being approximately 0.3 mm thick. The assembled SC was sealed with waterproof tape to prevent moisture evaporation from the device, facilitating subsequent electrochemical testing.

[0086] Given polyA3H1-E 50 The electrolyte has excellent overall performance, polyA3H1-E 50 The electrolyte was assembled into a supercapacitor to further investigate its electrochemical performance. Two sheets of carbon cloth loaded with the same mass of activated carbon were tightly bonded to polyA3H1-E. 50 A "sandwich" structure is formed on both sides of the electrolyte in a supercapacitor. First, a small amount of precursor solution is dropped onto the two electrodes of the capacitor to fully wet them. Then, the supercapacitor is simply sealed with waterproof tape, and relevant electrochemical tests are performed. Figure 11 As shown, the total thickness of the fabricated capacitor is approximately 0.9 mm, while the thickness of the electrolyte is approximately 0.3 mm. It can completely replace the liquid electrolyte and diaphragm, solving the leakage problem in energy storage devices.

[0087] The electrochemical window of SC is 100 mV s at room temperature. -1 The scan rate was determined by cyclic voltammetry (CV). Figure 12 Considering the decomposition voltage of water (1.23V), we selected a safe voltage (1V) that exhibits an almost perfectly rectangular shape as the final voltage window for SC. Therefore, subsequent related electrochemical tests were performed based on the 1V electrochemical window.

[0088] First, the CV and GCD curves of the SC were tested at room temperature, with a frequency sweep from 10 mV / s. -1 Up to 200mVs -1 The current density is from 0.05 A g. -1 up to 1A g -1 ,like Figure 13 a and Figure 13 As shown in b, the CV curve of SC exhibits a standard rectangle, and the GCD curve exhibits a standard triangle. Almost no voltage drop is observed in the GCD curve. When the temperature rises to 60℃, the CV and GCD curves of SC still maintain the standard rectangle and triangle shapes, but the area of ​​the CV curve increases slightly, and the discharge time of the GCD curve increases slightly. Figure 13 c, d). These results indicate that based on polyA3H1-E 50 The electrolyte SC exhibits ideal double-layer capacitance behavior at both room temperature and high temperature.

[0089] Subsequently, the performance of SC at low temperatures was investigated. Figure 14 Figure a shows the CV curves of SC at different temperatures, with a scan rate of 20 mV / s. -1 As the temperature decreases, the area under the CV curve gradually decreases. Even at the extreme low temperature of -40℃, the CV curve of the SC curve still exhibits a standard rectangular shape. Simultaneously, the GCD curve also maintains a triangular shape. Figure 14 b, 0.5A g -1 These all indicate that based on polyA3H1-E 50 The SC electrolyte exhibits good electrochemical performance at extremely low temperatures. Normally, decreasing temperature leads to a significant increase in the resistance of hydrogel electrolytes, but polyA3H1-E... 50 The resistance of the base SC only increased from 5.82Ω at 25℃ to 22.13Ω at -40℃ (compared to 5.08Ω at 60℃). Figure 14 As shown in c. From the low-frequency region of the EIS curve, it can be seen that the curve is almost parallel to the Y-axis, indicating that it is based on polyA3H1-E. 50 The electrolyte SC exhibits excellent ion diffusion capabilities. Notably, the ion diffusion behavior remains excellent even at extreme low temperatures of -40°C. This rapid ion diffusion behavior originates from polyA3H1-E. 50 The Grotthuss mechanism of protons within the electrolyte, which is also the mechanism of polyA3H1-E. 50 One of the main reasons why electrolytes can maintain good electrochemical performance and excellent ionic conductivity at extremely low temperatures (1.28 mS cm⁻¹) is... -1 , Figure 6 ).

[0090] In addition, we also tested the rate performance of SC at an extreme low temperature of -40℃, and the results are as follows: Figure 15 As shown, the area under the CV curves at different scan rates and the discharge time of the GCD curves at different current densities exhibit good rate-reduction relationships while maintaining perfect rectangular and triangular shapes. These results indicate that the polyA3H1-E... 50 The electrolyte SC exhibits good rate performance and standard double-layer capacitance behavior at low temperatures.

Claims

1. The application of a PolyAH-E hydrogel electrolyte in supercapacitors (SC); The preparation method of the PolyAH-E hydrogel electrolyte includes the following steps: S1, AM and AMPS monomers are dissolved in a mixed solution of ethylene glycol (EG) and water. S2, place the solution obtained in S1 in an ice bath and stir for 0.5~1.5 h until all monomers are dissolved. S3, add the initiator to the solution obtained in S2, stir in an ice bath for 20-40 minutes, and sonicate for 5-15 minutes to remove air bubbles to obtain the precursor solution; S4, inject the precursor solution into the mold, seal it and place it in an environment of 30~50 ℃ for polymerization for 8~16 h; in, The molar ratio of AM and AMPS monomers is (6:1) to (1:6), and the volume concentration of ethylene glycol in the mixed solution of ethylene glycol EG and water is 10% to 70%.

2. The use of the PolyAH-E hydrogel electrolyte as described in claim 1, characterized in that, In step S1, the ratio of monomer mass to mixed solution volume is 1:2 to 1:4; The volume concentration of ethylene glycol in a mixed solution of ethylene glycol (EG) and water is 30% to 70%.

3. The use of the PolyAH-E hydrogel electrolyte as described in claim 1, characterized in that, In step S2, the solution obtained in S1 is placed in an ice bath and stirred for 0.8 to 1.2 h.

4. The use of the PolyAH-E hydrogel electrolyte as described in claim 1, characterized in that, In step S3, the initiator is APS, and the amount of initiator added is 0.5~1.5 wt% of the monomer mass.

5. The use of the PolyAH-E hydrogel electrolyte as described in claim 4, characterized in that, The amount of initiator added is 1 wt% of the monomer mass.

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