阅读说明：本技术 一种超级电容器高电压、宽温区水系电解液的制备方法 (Preparation method of high-voltage wide-temperature-area aqueous electrolyte of super capacitor ) 是由 李磊 汤成 王亚玲 张岩 于 2021-09-10 设计创作，主要内容包括：本发明公开了一种超级电容器高电压、宽温区水系电解液的制备方法,包括：步骤1：使用在水中具有高溶解度的盐配制成水溶液,混合均匀形成“盐包水”结构溶液A；步骤2：将无水有机溶剂加入步骤1配制的溶液A中混合均匀,形成均一溶液B；步骤3：向溶液B中加入在水中具有高溶解度的盐,混合均匀形成若干不同浓度的具有高工作电压、宽工作温度区间的水系电解液C。(The invention discloses a preparation method of a high-voltage wide-temperature-area aqueous electrolyte of a super capacitor, which comprises the following steps: step 1: preparing an aqueous solution by using salt with high solubility in water, and uniformly mixing to form a 'water-in-salt' structural solution A; step 2: adding an anhydrous organic solvent into the solution A prepared in the step 1, and uniformly mixing to form a uniform solution B; and step 3: and adding salt with high solubility in water into the solution B, and uniformly mixing to form a plurality of water-based electrolytes C with different concentrations, high working voltage and wide working temperature range.)

1. A preparation method of a high-voltage wide-temperature-area aqueous electrolyte of a super capacitor is characterized by comprising the following steps:

step 1: preparing an aqueous solution by using salt with high solubility in water, and uniformly mixing to form a 'water-in-salt' structural solution A;

step 2: adding an anhydrous organic solvent into the solution A prepared in the step 1, and uniformly mixing to form a uniform solution B;

and step 3: and adding salt with high solubility in water into the solution B, and uniformly mixing to form a plurality of water-based electrolytes C with different concentrations, high working voltage and wide working temperature range.

2. The method for preparing the high-voltage wide-temperature-range aqueous electrolyte of the supercapacitor according to claim 1, wherein the salt with high solubility in water in the step 1 is one or more of lithium bistrifluoromethanesulfonylimide, sodium perchlorate, zinc chloride, lithium nitrate and sodium nitrate.

3. The method for preparing the supercapacitor high-voltage wide-temperature-zone aqueous electrolyte according to claim 1, wherein the anhydrous organic solvent in step 2 is one or more of anhydrous acetonitrile, anhydrous dimethylformamide, anhydrous ethanol, anhydrous dimethyl sulfoxide and anhydrous dimethyl carbonate.

4. The method for preparing the high-voltage wide-temperature-range aqueous electrolyte of the supercapacitor according to claim 1, wherein the mass fraction of the anhydrous organic solvent in the total solvent in the step 2 is 0-100%.

5. The method for preparing a supercapacitor high-voltage wide-temperature-range aqueous electrolyte according to claim 1, wherein the salt with high solubility in water in step 3 is one or more of lithium bistrifluoromethanesulfonylimide, sodium perchlorate, zinc chloride, lithium nitrate and sodium nitrate.

6. The method for preparing the supercapacitor high-voltage wide-temperature-range aqueous electrolyte according to claim 1, wherein the amount of the salt having high solubility in water added in step 3 is 0 g or more.

7. The method for preparing the high-voltage wide-temperature-range aqueous electrolyte of the super capacitor according to claim 1, wherein the super capacitor using the electrolyte can stably operate at a voltage of-2.4V and a temperature range of-40-90 ℃.

Technical Field

The invention belongs to the field of preparation of electrolyte of a super capacitor, and particularly relates to a preparation method of high-voltage wide-temperature-area aqueous electrolyte of a super capacitor.

Background

The super capacitor is an important component of a power system and has the characteristics of high power density, good cycle stability, high safety and the like. The development of power systems places higher demands on supercapacitors, particularly with regard to performance in terms of high energy density and wide operating temperature range. The electrolyte has a direct effect on both the energy density and the operating temperature range performance of the supercapacitor. Three types of electrolytes developed to date mainly include aqueous electrolytes, organic electrolytes and ionic liquid electrolytes. Among these electrolytes, water-based electrolytes have attracted considerable attention mainly due to their advantages of high ionic conductivity, low cost, nonflammability, low operating requirements, and the like. However, due to its lower thermodynamically stable potential window (1.23V), the operating potential window of aqueous electrolytes is correspondingly lower (< 1.0V). Meanwhile, the working temperature range of the water system electrolyte is narrow due to the characteristics that water is easy to freeze in a low-temperature environment and is easy to volatilize in a high-temperature environment. These two challenges hinder the development of high performance water-based supercapacitors. Therefore, increasing the operating potential window and the operating temperature range of the aqueous electrolyte is an urgent need for the industrial development of the aqueous supercapacitor.

Disclosure of Invention

The invention aims to provide a preparation method of a high-voltage wide-temperature-range aqueous electrolyte of a super capacitor. Firstly, salt with high solubility in water is prepared into aqueous solution, and the aqueous solution is uniformly mixed to form 'water-in-salt' structural solution A. Then selecting anhydrous organic solvent with good interface stability, adding the anhydrous organic solvent into the prepared solution according to a certain proportion, and uniformly mixing to form uniform solution B. After the proportion of the anhydrous organic solvent and the water is adjusted, salt with high solubility in the water is continuously added into the system and is uniformly mixed to form a uniform solution C. The high-concentration salt enlarges the working potential window of the electrolyte, enables the electrolyte to work stably at high temperature, and the anhydrous organic solvent and water form hydrogen bonds to prevent the formation of the hydrogen bonds between water molecules, thereby obviously reducing the freezing point of the electrolyte and widening the low-temperature working temperature range of the electrolyte.

The invention is realized by adopting the following technical scheme:

a preparation method of a high-voltage wide-temperature-area aqueous electrolyte of a super capacitor comprises the following steps:

step 1: preparing an aqueous solution by using salt with high solubility in water, and uniformly mixing to form a 'water-in-salt' structural solution A;

step 2: adding an anhydrous organic solvent into the solution A prepared in the step 1, and uniformly mixing to form a uniform solution B;

and step 3: and adding salt with high solubility in water into the solution B, and uniformly mixing to form a plurality of water-based electrolytes C with different concentrations, high working voltage and wide working temperature range.

In a further improvement of the invention, the salt with high solubility in water in step 1 is one or more of lithium bistrifluoromethanesulfonylimide, sodium perchlorate, zinc chloride, lithium nitrate and sodium nitrate.

In a further improvement of the invention, the anhydrous organic solvent in the step 2 is one or more of anhydrous acetonitrile, anhydrous dimethylformamide, anhydrous ethanol, anhydrous dimethyl sulfoxide and anhydrous dimethyl carbonate.

The invention further improves that the mass fraction of the anhydrous organic solvent in the total solvent in the step 2 is any proportion between 0 and 100 percent.

In a further improvement of the invention, the salt with high solubility in water in step 3 is one or more of lithium bistrifluoromethanesulfonylimide, sodium perchlorate, zinc chloride, lithium nitrate and sodium nitrate.

In a further development of the invention, the salt with high solubility in water is added in step 3 in an amount of 0 g or more.

The invention has the further improvement that the super capacitor using the electrolyte can stably operate at the voltage of 2.4V and the temperature range of-40-90 ℃.

Compared with the prior art, the invention has at least the following beneficial technical effects:

the preparation method of the aqueous electrolyte is simple and ingenious, has higher working voltage, wider working temperature range and excellent electrochemical performance compared with the traditional aqueous electrolyte, and is green, environment-friendly and easy to scale.

The invention utilizes the coordination of high-concentration salt and water molecules to reduce the activity of the water molecules, thereby achieving the purposes of enlarging the working potential window of the electrolyte and stably working the electrolyte at high temperature, and the method is simple and effective.

The invention utilizes the hydrogen bond action between the anhydrous organic solvent and the water molecules, and prevents the formation of the hydrogen bond between the water molecules by introducing a proper amount of the anhydrous organic solvent into the system, thereby obviously reducing the freezing point of the electrolyte and endowing the electrolyte with low-temperature performance.

By adjusting different proportions of water, an anhydrous organic solvent and salt in the electrolyte, a series of prepared electrolytes can meet the requirements of different working voltages and working environment temperatures.

Since anhydrous organic solvents generally have a significantly lower price than salts, the introduction of anhydrous organic solvents in the present invention reduces the cost of the overall electrolyte.

Drawings

FIG. 1 is a diagram of a substance of an electrolyte prepared in example 1 of the present invention, in which the selected salt is lithium bis (trifluoromethanesulfonyl) imide;

FIG. 2 is a graphical representation of the electrochemical stability window of electrolytes formulated in examples 1-4;

fig. 3 is a cyclic voltammogram and a constant current charge and discharge curve of example 1, wherein fig. 3(a) is the cyclic voltammogram of example 1, and fig. 3(b) is the constant current charge and discharge curve of example 1;

FIG. 4 is a cycle stability characterization of example 4;

FIG. 5 is a low temperature electrochemical performance characterization and low temperature (-65 ℃) flow test of example 1; wherein, fig. 5(a) is cyclic voltammetry curves of example 1 under different low temperature environments, fig. 5(b) is constant current charge and discharge curves of example 1 under different low temperature environments, and fig. 5(c) is a fluidity test of example 1 under-65 ℃;

fig. 6 is a high-temperature electrochemical performance characterization of example 4, wherein fig. 6(a) is a cyclic voltammetry curve of example 4 at 90 ℃, and fig. 6(b) is a constant current charge and discharge curve of example 4 under different high-temperature environments.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The invention provides a preparation method of a high-voltage wide-temperature-area aqueous electrolyte of a super capacitor, which comprises the following specific steps:

1. preparing an aqueous solution by using salt with high solubility in water, and uniformly mixing to form a 'water-in-salt' structural solution A;

the salt with high solubility in water is one or more of lithium bistrifluoromethanesulfonylimide, sodium perchlorate, zinc chloride, lithium nitrate and sodium nitrate. The concentration of salt in the aqueous solution prepared is any concentration that will form a water-in-salt system.

2. Adding an anhydrous organic solvent into the solution prepared in the step 1 according to a certain proportion, and uniformly mixing to form a uniform solution B;

the anhydrous organic solvent is one or a combination of more of anhydrous acetonitrile, anhydrous dimethylformamide, anhydrous ethanol, anhydrous dimethyl sulfoxide, anhydrous dimethyl carbonate and other organic solvents, and the mass fraction of the anhydrous organic solvent in the total solvent is 0-100%.

3. Determining the proper proportion of the anhydrous organic solvent and the water, continuously adding a proper amount of salt with high solubility in the water into the system, and uniformly mixing to form a plurality of uniform mixed solutions with different concentrations.

The salt with high solubility in water is one or more of lithium bistrifluoromethanesulfonylimide, sodium perchlorate, zinc chloride, lithium nitrate and sodium nitrate. The salt having high solubility in water is added in an amount of 0 g or more.

Fig. 1 is a diagram of a water-based electrolyte prepared in example 1 of the present invention, and it can be seen that the prepared water-based electrolyte is a colorless and transparent uniform solution, and the salt selected in this example is lithium bis (trifluoromethanesulfonyl) imide;

FIG. 2 shows that the electrochemical stability window of the prepared water-based electrolyte is significantly higher than that of the traditional water-based electrolyte (about 1.23V);

figure 3 shows that the formulated aqueous electrolyte has significant electric double layer capacitor characteristics;

FIG. 4 shows that the prepared water-based electrolyte has good cycle stability;

FIG. 5 shows that the prepared aqueous electrolyte has good low-temperature electrochemical performance, and can maintain fluidity at-65 ℃;

fig. 6 shows that the prepared aqueous electrolyte has good high-temperature electrochemical stability.

Example 1

(1) Weighing 6.029g of bis (trifluoromethanesulfonyl) imide lithium, dissolving in 1mL of deionized water, and uniformly mixing to form a uniform solution;

(2) weighing 0.2mL of anhydrous organic solvent, adding the anhydrous organic solvent into the solution prepared in the step 1, and uniformly mixing to form a uniform solution;

example 2

(1) Weighing 6.029g of bis (trifluoromethanesulfonyl) imide lithium, dissolving in 1mL of deionized water, and uniformly mixing to form a uniform solution;

(2) weighing 0.2mL of anhydrous organic solvent, adding the anhydrous organic solvent into the solution prepared in the step 1, and uniformly mixing to form a uniform solution;

(3) and (3) continuously weighing 0.38g of lithium bis (trifluoromethanesulfonyl) imide, adding the lithium bis (trifluoromethanesulfonyl) imide into the solution prepared in the step (2), and uniformly mixing to form a uniform solution.

Example 3

(1) Weighing 6.029g of bis (trifluoromethanesulfonyl) imide lithium, dissolving in 1mL of deionized water, and uniformly mixing to form a uniform solution;

(2) weighing 0.2mL of anhydrous organic solvent, adding the anhydrous organic solvent into the solution prepared in the step 1, and uniformly mixing to form a uniform solution;

(3) and (3) continuously weighing 0.76g of lithium bis (trifluoromethanesulfonyl) imide, adding the lithium bis (trifluoromethanesulfonyl) imide into the solution prepared in the step (2), and uniformly mixing to form a uniform solution.

Example 4

(1) Weighing 6.029g of bis (trifluoromethanesulfonyl) imide lithium, dissolving in 1mL of deionized water, and uniformly mixing to form a uniform solution;

(2) weighing 0.2mL of anhydrous organic solvent, adding the anhydrous organic solvent into the solution prepared in the step 1, and uniformly mixing to form a uniform solution;

(3) and (3) continuously weighing 1.14g of lithium bis (trifluoromethanesulfonyl) imide, adding into the solution prepared in the step (2), and uniformly mixing to form a uniform solution.

Example 5

(1) Weighing 6.029g of bis (trifluoromethanesulfonyl) imide lithium, dissolving in 1mL of deionized water, and uniformly mixing to form a uniform solution;

(2) weighing 0.4mL of anhydrous organic solvent, adding the anhydrous organic solvent into the solution prepared in the step 1, and uniformly mixing to form a uniform solution;

(3) and (3) continuously weighing 0.76g of lithium bis (trifluoromethanesulfonyl) imide, adding the lithium bis (trifluoromethanesulfonyl) imide into the solution prepared in the step (2), and uniformly mixing to form a uniform solution.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.