Preparation method and application of low-temperature resistant high-pressure chlorine-based electrolyte solution

Abstract

A preparation method and application of a low-temperature and high-pressure chlorine-based electrolyte solution, which belongs to a preparation method and application of an electrolyte solution. The purpose of the present invention is to solve the problem that existing aqueous electrolytes are easy to freeze at low temperatures and the electrolyte has a narrow stable electrochemical window. Method: CaCl2 or AlCl3 and Zn(ClO4)2 are added to deionized water, and magnetic stirring is performed for a period of time to obtain a low-temperature and high-pressure chlorine-based electrolyte solution. A low-temperature and high-pressure chlorine-based electrolyte solution is used in supercapacitors. The present invention uses Zn(ClO4)2 to broaden the voltage window of the CaCl2 electrolyte and lower its freezing point. The low eutectic solvent electrolyte based on CaCl2 and Zn(ClO4)2 with an extremely low freezing point can be used to construct an aqueous supercapacitor that works stably at ‑40°C and has an operating voltage of 0 to 1.8V.

Description

Technical Field

[0001] The invention relates to a preparation method and application of an electrolyte solution. Background Art

[0002] Supercapacitors have gained widespread application due to their long cycle life and high power density, but their use at low temperatures remains limited. Ensuring that supercapacitors maintain their excellent performance at low temperatures has become a major concern. Supercapacitors primarily consist of electrode materials, electrolytes, separators, and current collectors. The electrode materials and electrolyte play a crucial role in supercapacitor performance, with the electrolyte's impact becoming even more pronounced at low temperatures. Traditional commercial supercapacitors utilize organic electrolytes, but these have inherent drawbacks such as high cost, toxicity, and flammability, which directly impact the cost and safety of commercial supercapacitors. In contrast, aqueous electrolytes are non-flammable, environmentally friendly, and low-cost, completely overcoming the safety issues faced by organic electrolytes. Furthermore, aqueous electrolytes do not require a harsh, dry environment for preparation and use, significantly simplifying the supercapacitor assembly process and reducing costs. Aqueous electrolytes also have high electrical conductivity, typically two orders of magnitude higher than organic electrolytes. This high conductivity helps reduce the internal resistance of supercapacitors, thereby improving the device's rate capability. Therefore, the development of high-power, high-energy-density, and long-cycle stable aqueous supercapacitors is a research hotspot at this stage. However, the viscosity of aqueous electrolytes increases or even freezes at low temperatures, causing the ionic conductivity to drop sharply, resulting in capacity decay or even inability of aqueous supercapacitors to work, limiting their use in low-temperature environments. Chloride-based salts are highly soluble, and the resulting aqueous solutions have good fluidity at low temperatures, a low melting point, low cost, and are easy to prepare and mass-produce. They are widely used in food freezing and preservation (<-20°C), making them a promising class of low-temperature electrolytes. However, chlorine-based electrolytes have a low operating voltage and are prone to chlorine evolution reactions or oxygen / hydrogen evolution reactions. Theoretically, the output voltage of aqueous supercapacitors is difficult to exceed 1.23V while ensuring that the electrolyte does not decompose, resulting in low operating voltage and specific energy density of the supercapacitor. Therefore, improving the operating voltage of chlorine-based aqueous supercapacitors has become the key to achieving high-performance aqueous supercapacitors. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems that existing aqueous electrolytes are prone to freezing at low temperatures and have a narrow electrochemical window for stable electrolytes, and to provide a preparation method and application of a low-temperature resistant, high-pressure chlorine-based electrolyte solution.

[0004] A method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution is specifically completed by the following steps:

[0005] CaCl2 or AlCl3 and Zn(ClO4)2 are added to deionized water and magnetically stirred for a period of time to obtain a low-temperature and high-pressure chlorine-based electrolyte solution;

[0006] The concentration of CaCl2 or AlCl3 in the low-temperature-resistant and high-pressure chlorine-based electrolyte solution is 2 mol / L to 3 mol / L, and the concentration of Zn(ClO4)2 is 1 mol / L to 3 mol / L.

[0007] A low-temperature-resistant and high-pressure chlorine-based electrolyte solution is used in supercapacitors.

[0008] Advantages of the present invention:

[0009] The present invention addresses the challenges faced by aqueous electrolytes in terms of easy freezing at low temperatures and the narrow electrochemical window of electrolyte stability. By regulating the functions of the electrolyte system, the present invention achieves the efficient construction of a low-temperature and wide-voltage window chlorine-based aqueous electrolyte. The present invention uses Zn(ClO4)2 (zinc perchlorate) to broaden the voltage window of the CaCl2 (calcium chloride) electrolyte and lower its freezing point. The resulting low-freezing point eutectic solvent electrolyte based on CaCl2 and Zn(ClO4)2 can be used to construct an aqueous supercapacitor that can operate stably at -40°C and has an operating voltage of 0 to 1.8V. In addition, the present invention uses Zn(ClO4)2 to improve the voltage window of the AlCl3 (aluminum chloride) electrolyte. The aqueous supercapacitor assembled with this electrolyte has an operating voltage of 0 to 1.8V and can operate stably at -40°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Photographs of various electrolytes at -40°C, in which 1 is a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L; 2 is a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L; 3 is a 2 mol / L AlCl3 solution; 4 is a 3 mol / L Zn(ClO4)2 solution; 5 is a 3 mol / L CaCl2 solution; 6 is a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 3, wherein the concentration of Zn(ClO4)2 is 1 mol / L and the concentration of CaCl2 is 3 mol / L; 7 is a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 4, wherein the concentration of Zn(ClO4)2 is 2 mol / L and the concentration of CaCl2 is 3 mol / L;

[0011] Figure 2 The scanning rate was 0.1 V s at room temperature for 3 mol / L CaCl2 solution and 2 mol / L AlCl3 solution. -1CV curves, (a) is 3 mol / L CaCl2 solution, (b) is 2 mol / L AlCl3 solution;

[0012] Figure 3 The low temperature resistant high pressure chlorine-based electrolyte solution prepared in Examples 1 and 2 has a scanning rate of 0.1 Vs at room temperature. -1 CV curves, in which (a) is a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L; (b) is a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L;

[0013] Figure 4 The low-temperature resistant high-pressure chlorine-based electrolyte solution prepared in Examples 1 and 2 has a scanning rate of 0.1 V s at 0°C, -10°C, -20°C, -30°C, and -40°C. -1 CV curves, in which (a) is a CP diagram of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, (b) is a CV diagram of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2·6H2O is 3 mol / L and the concentration of CaCl2 is 3 mol / L, (c) is a CP diagram of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L, (d) is a CV diagram of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L. DETAILED DESCRIPTION

[0014] Specific embodiment 1: This embodiment provides a method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution, which is specifically completed by the following steps:

[0015] CaCl2 or AlCl3 and Zn(ClO4)2 are added to deionized water and magnetically stirred for a period of time to obtain a low-temperature and high-pressure chlorine-based electrolyte solution;

[0016] The concentration of CaCl2 or AlCl3 in the low-temperature-resistant and high-pressure chlorine-based electrolyte solution is 2 mol / L to 3 mol / L, and the concentration of Zn(ClO4)2 is 1 mol / L to 3 mol / L.

[0017] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the concentration of CaCl2 or AlCl3 in the low-temperature, high-pressure chlorine-based electrolyte solution is 3 mol / L, and the concentration of Zn(ClO4)2 is 1 mol / L. The other steps are the same as those in specific embodiment 1.

[0018] Specific embodiment 3: This embodiment differs from specific embodiments 1 or 2 in that the concentration of CaCl2 or AlCl3 in the low-temperature, high-pressure chlorine-based electrolyte solution is 3 mol / L, and the concentration of Zn(ClO4)2 is 2 mol / L. The other steps are the same as those in specific embodiments 1 or 2.

[0019] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the concentration of CaCl2 or AlCl3 in the low-temperature, high-pressure chlorine-based electrolyte solution is 3 mol / L, and the concentration of Zn(ClO4)2 is 3 mol / L. The other steps are the same as specific embodiments 1 to 3.

[0020] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the concentration of CaCl2 or AlCl3 in the low-temperature, high-pressure chlorine-based electrolyte solution is 2 mol / L, and the concentration of Zn(ClO4)2 is 3 mol / L. The other steps are the same as specific embodiments 1 to 4.

[0021] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the magnetic stirring speed is 300 rpm to 600 rpm and the magnetic stirring time is 1 to 2 hours. The other steps are the same as those of specific embodiments 1 to 5.

[0022] Specific embodiment seven: This embodiment is an application of a low-temperature and high-pressure chlorine-based electrolyte solution in a supercapacitor.

[0023] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the supercapacitor is assembled as follows:

[0024] 1. Preparation of electrodes:

[0025] Activated carbon, carbon nanotubes, and polyvinylidene fluoride were weighed in a mass ratio of 95:3:2, uniformly mixed, and fully ground to obtain a mixture; N-methylpyrrolidone was added dropwise to the mixture, and stirred for a period of time to obtain a slurry;

[0026] 2. Coating:

[0027] The slurry is evenly coated on carbon paper and then placed in an oven to dry to obtain electrodes; the electrodes are used as positive and negative electrodes;

[0028] 3. Device assembly:

[0029] Assemble the button capacitor in the order of positive electrode shell, positive electrode sheet, glass fiber separator, negative electrode sheet, gasket, spring, and negative electrode shell. Drop electrolyte on one side of the glass fiber separator to obtain a supercapacitor. The other steps are the same as those in Specific Embodiments 1 to 7.

[0030] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the activated carbon in step 1 is YP-50F activated carbon; the grinding time in step 1 is 30 to 60 minutes; the stirring time in step 1 is 5 to 7 hours; and the volume ratio of the mixture in step 1 to N-methylpyrrolidone is 1g:(3mL to 5mL). The other steps are the same as specific embodiments 1 to 8.

[0031] Specific Embodiment 10: This embodiment differs from Specific Embodiments 1 to 9 in that the drying temperature in step 2 is 70°C to 80°C and the drying time is 10 to 12 hours; the amount of electrolyte applied to the glass fiber separator in step 3 is 70 to 100 μL, and the diameter of the glass fiber separator is 18 mm. The other steps are the same as Specific Embodiments 1 to 9.

[0032] The following examples are used to verify the beneficial effects of the present invention:

[0033] Example 1: A method for preparing a low-temperature, high-pressure chlorine-based electrolyte solution, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L, is specifically completed by the following steps:

[0034] AlCl3 and Zn(ClO4)2 were added to deionized water and stirred at 450 r / min for 1 h to obtain a low-temperature and high-pressure chlorine-based electrolyte solution;

[0035] The concentration of AlCl3 in the low-temperature-resistant high-pressure chlorine-based electrolyte solution is 2 mol / L, and the concentration of Zn(ClO4)2 is 3 mol / L.

[0036] Example 2: A method for preparing a low-temperature, high-pressure chlorine-based electrolyte solution, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, is specifically completed by the following steps:

[0037] CaCl2 and Zn(ClO4)2 were added to deionized water and stirred at 450 r / min for 1 h to obtain a low-temperature and high-pressure chlorine-based electrolyte solution;

[0038] The concentration of CaCl2 in the low-temperature-resistant high-pressure chlorine-based electrolyte solution is 3 mol / L, and the concentration of Zn(ClO4)2 is 3 mol / L.

[0039] Example 3: A method for preparing a low-temperature, high-pressure chlorine-based electrolyte solution, wherein the concentration of Zn(ClO4)2 is 1 mol / L and the concentration of CaCl2 is 3 mol / L, is specifically completed by the following steps:

[0040] Add CaCl2 and Zn(ClO4)2 into deionized water and stir at 450r / min for 1h to obtain a low-temperature and high-pressure chlorine-based electrolyte solution;

[0041] The concentration of CaCl2 in the low-temperature-resistant high-pressure chlorine-based electrolyte solution is 3 mol / L, and the concentration of Zn(ClO4)2 is 1 mol / L.

[0042] Example 4: A method for preparing a low-temperature, high-pressure chlorine-based electrolyte solution, wherein the concentration of Zn(ClO4)2 is 2 mol / L and the concentration of CaCl2 is 3 mol / L, is specifically completed by the following steps:

[0043] CaCl2 and Zn(ClO4)2 were added to deionized water and stirred at 450 r / min for 1 h to obtain a low-temperature and high-pressure chlorine-based electrolyte solution;

[0044] The concentration of CaCl2 in the low-temperature-resistant high-pressure chlorine-based electrolyte solution is 3 mol / L, and the concentration of Zn(ClO4)2 is 2 mol / L.

[0045] The low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L; the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L; 2 mol / L AlCl3 solution; 3 mol / L Zn(ClO4)2 solution; 3 mol / L CaCl2 solution; the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 3, wherein the concentration of Zn(ClO4)2 is 1 mol / L and the concentration of CaCl2 is 3 mol / L; and the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 4, wherein the concentration of Zn(ClO4)2 is 2 mol / L and the concentration of CaCl2 is 3 mol / L, are maintained at -40°C for 48 h to observe whether the electrolyte crystallizes.

[0046] from Figure 1It can be seen that the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, and the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L, still maintain liquid and fluid properties even at -40°C, while the 3 mol / L CaCl2 solution, 2 mol / L AlCl3 solution, 3 mol / L Zn(ClO4)2 solution and the control CaCl2 and Zn(ClO4)2 electrolytes of other concentrations are completely frozen and lose fluidity. Obviously, the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, in which the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, has a significantly lower freezing point than the electrolyte with a conventional concentration of 1 mol / L or 2 mol / L Zn(ClO4)2 and 3 mol / L CaCl2 (the low-temperature and high-pressure chlorine-based electrolyte solutions prepared in Example 3 and Example 4). At the same time, the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, in which the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L, has a significantly lower freezing point than the 2 mol / L AlCl3 solution and the 3 mol / L Zn(ClO4)2 solution. Water molecules contain positively charged hydrogen atoms and negatively charged oxygen atoms. Hydrogen bonds are mainly formed by electrostatic interactions between oxygen atoms and hydrogen atoms in adjacent water molecules. Pure water contains a large number of hydrogen bond structures and is prone to freezing when the temperature is below zero degrees. In the initial nucleation process of ice formation, water molecules with tetrahedral coordination structure grow into stacked hexagonal sequences of ice. Therefore, regulating the number of hydrogen bonds and reducing the number of water molecules rich in hydrogen bonds can effectively inhibit the freezing of water from a kinetic perspective. 2+ 、Zn 2+ 、Al 3+ The number of hydrogen bonds is greatly reduced. 2+ 、Zn 2+ 、Al 3+ The ions will form a strong electric field, which will produce strong electrostatic interactions with the dipole water molecules, causing Ca 2+ 、Zn 2+ 、Al 3+ The coordination structure of water molecules around the ions is rearranged. The O atoms in the water molecules are bound by the metal ions through hydration and hardly participate in the formation of hydrogen bonds. At the same time, Cl - 、ClO4 - It also binds H atoms, thus greatly reducing the number of hydrogen bonds. In summary, the hydrogen bond structure in the electrolyte can be changed by adjusting the concentration of salt and the type of cations in the electrolyte, and the freezing point of the electrolyte can be controlled to obtain an electrolyte that does not freeze at low temperatures.

[0047] The electrochemical performance of button-type supercapacitors assembled using a 3 mol / L CaCl2 solution, a 2 mol / L AlCl3 solution, a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, and a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L, was tested by a Shanghai Chenhua Instrument Co., Ltd. CHI660E electrochemical workstation. The assembly method is as follows:

[0048] Assembling the supercapacitor:

[0049] 1. Preparation of electrodes:

[0050] YP-50F activated carbon, carbon nanotubes, and polyvinylidene fluoride were weighed in a mass ratio of 95:3:2, uniformly mixed, and fully ground for 30 minutes to obtain a mixture; N-methylpyrrolidone was added dropwise to the mixture, and stirred for 6 hours to obtain a slurry;

[0051] The mass ratio of the mixture described in step 1 to the volume ratio of N-methylpyrrolidone is 1g:4mL;

[0052] 2. Coating:

[0053] The slurry is evenly coated on carbon paper, and then placed in an oven at 80°C and dried for 12 hours to obtain an electrode; the electrode is used as a positive electrode sheet and a negative electrode sheet;

[0054] 3. Device assembly:

[0055] Assemble the button capacitor in the order of positive electrode shell, positive electrode sheet, glass fiber separator, negative electrode sheet, gasket, spring, and negative electrode shell, and drip the electrolyte on one side of the glass fiber separator to obtain a supercapacitor;

[0056] The amount of the electrolyte described in step 3 on one side of the glass fiber separator is 80 μL, and the diameter of the glass fiber separator is 18 mm.

[0057] Figure 2 The scanning rate was 0.1 V s at room temperature for 3 mol / L CaCl2 solution and 2 mol / L AlCl3 solution. -1 CV curves, (a) is 3 mol / L CaCl2 solution, (b) is 2 mol / L AlCl3 solution;

[0058] Figure 3 The low temperature resistant high pressure chlorine-based electrolyte solution prepared in Examples 1 and 2 has a scanning rate of 0.1 Vs at room temperature. -1CV curves, in which (a) is a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L; (b) is a low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L;

[0059] from Figure 2 From (a) and (b), we can see that the voltage window of 3 mol / L CaCl2 solution and 2 mol / L AlCl3 solution is relatively narrow, around 0 to 1 V.

[0060] from Figure 3 (a) It can be seen that the CV curve of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, in which the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, is nearly rectangular, showing excellent electric double layer capacitance characteristics. It can also be clearly observed that Zn(ClO4)2 significantly increases the voltage window of CaCl2. Figure 3 (b) It can be seen that the CV curve of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, in which the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L, has an overall shape that is approximately rectangular. A slight redox peak can be observed, indicating that the capacity may be provided not only by the double-layer capacitor but also by the pseudocapacitor. At the same time, it can also be found that the voltage window of AlCl3 is significantly improved after adding Zn(ClO4)2. Taking into account the reversibility and electrolytic decomposition of the device, the low-temperature and high-pressure chlorine-based electrolyte solutions prepared in Examples 1 and 2 select a voltage range of 0 to 1.8 V as the operating voltage range of the device.

[0061] Figure 4 The low-temperature resistant high-pressure chlorine-based electrolyte solution prepared in Examples 1 and 2 has a scanning rate of 0.1 V s at 0°C, -10°C, -20°C, -30°C, and -40°C. -1CV curves, (a) is a CP diagram of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, (b) is a CV diagram of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, (c) is a CP diagram of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L, (d) is a CV diagram of the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L.

[0062] from Figure 4 In (a), it can be observed that at 0°C, the capacity of the supercapacitor prepared using the low-temperature resistant high-pressure chlorine-based electrolyte solution prepared in Example 2, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of CaCl2 is 3 mol / L, is 30.611 F g -1 , while at -10℃, -20℃, -30℃ and -40℃, the capacity is 29.056F g -1 、26.000F g -1 、18.389F g -1 、10.889F g -1 Compared with 0℃, the capacity retention rates at different temperatures from high to low are 94.92%, 84.94%, 60.07%, and 35.572% respectively. As the temperature decreases, the capacity of the supercapacitor also gradually decreases. Figure 4 The redox peak is clearly observed in (b), which provides more capacity for the supercapacitor. The capacity retention rate decreases significantly at -30℃ and -40℃, which may be due to the inhibition of the redox reaction as the temperature decreases, resulting in a decrease in capacity. Further exploration of the redox reaction mechanism is needed to help better improve the capacity of the electrolyte. Figure 4 (c) It can be seen that the low-temperature and high-pressure chlorine-based electrolyte solution prepared in Example 1, wherein the concentration of Zn(ClO4)2 is 3 mol / L and the concentration of AlCl3 is 2 mol / L, has a discharge capacity of 39.667 F g-1 at 0°C, -10°C, -20°C, -30°C, and -40°C, respectively. -1 、35.556F g -1 、28.500F g -1 、19.440F g -1 、10.667F g -1Compared with 0℃, the capacity retention rates at -10℃, -20℃, -30℃ and -40℃ are 89.64%, 71.85%, 49.00% and 26.89% respectively. The redox peak can also be seen in 4(d). It can be inferred that the main - 、ClO4 - The redox reaction between Zn(ClO4)2 and AlCl3 is related to the redox reaction between them, which provides a higher discharge capacity for supercapacitors. In summary, Zn(ClO4)2 can significantly increase the voltage window of chlorine-based electrolytes (CaCl2, AlCl3), and the assembled supercapacitors have good performance at low temperatures.

Claims

1. A method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution, characterized in that The low-temperature and high-pressure chlorine-based electrolyte solution prepared by the preparation method is used in supercapacitors. The supercapacitor assembled using the electrolyte solution has an operating voltage of 0-1.8V and can operate stably at -40°C. The preparation method is specifically completed according to the following steps: CaCl2 or AlCl3 and Zn(ClO4)2 are added to deionized water and magnetically stirred for a period of time to obtain a low-temperature and high-pressure chlorine-based electrolyte solution; The concentration of CaCl2 or AlCl3 in the low-temperature-resistant and high-pressure chlorine-based electrolyte solution is 2 mol / L to 3 mol / L, and the concentration of Zn(ClO4)2 is 3 mol / L.

2. The method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution according to claim 1, characterized in that The concentration of CaCl2 or AlCl3 in the low-temperature-resistant and high-pressure chlorine-based electrolyte solution is 3 mol / L, and the concentration of Zn(ClO4)2 is 3 mol / L.

3. The method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution according to claim 1, characterized in that The concentration of CaCl2 or AlCl3 in the low-temperature-resistant and high-pressure chlorine-based electrolyte solution is 2 mol / L, and the concentration of Zn(ClO4)2 is 3 mol / L.

4. The method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution according to claim 1, characterized in that The speed of the magnetic stirring is 300 r / min to 600 r / min, and the time of the magnetic stirring is 1 h to 2 h.

5. The method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution according to claim 1, characterized in that The assembly method of the supercapacitor is completed as follows:

1. Preparation of electrodes: Activated carbon, carbon nanotubes, and polyvinylidene fluoride were weighed in a mass ratio of 95:3:2, uniformly mixed, and fully ground to obtain a mixture; N-methylpyrrolidone was added dropwise to the mixture, and stirred for a period of time to obtain a slurry; 2. Coating: The slurry is evenly coated on carbon paper and then placed in an oven to dry to obtain electrodes; the electrodes are used as positive and negative electrodes; 3. Device assembly: The button capacitor is assembled in the order of positive electrode shell, positive electrode sheet, glass fiber separator, negative electrode sheet, gasket, spring and negative electrode shell, and the electrolyte solution is dripped on one side of the glass fiber separator to obtain a supercapacitor.

6. The method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution according to claim 5, characterized in that The activated carbon described in step one is YP-50F activated carbon; the grinding time described in step one is 30min~60min; the stirring time described in step one is 5h~7h; the volume ratio of the mass of the mixture described in step one to N-methylpyrrolidone is 1g:(3mL~5mL).

7. The method for preparing a low-temperature resistant high-pressure chlorine-based electrolyte solution according to claim 5, characterized in that The drying temperature in step 2 is 70° C. to 80° C., and the drying time is 10 h to 12 h. The amount of the electrolyte solution applied to the glass fiber separator in step 3 is 70 to 100 μL, and the diameter of the glass fiber separator is 18 mm.

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