CN114530656A - Preparation method of high DN (DN) value electrolyte applied to lithium-gas battery and electrolyte - Google Patents

Abstract

The invention provides a preparation method of high DN value electrolyte applied to a lithium-gas battery, which comprises the following steps: s1: dissolving lithium perchlorate in dimethyl sulfoxide (DMSO), and fully stirring to fully dissolve the lithium perchlorate to obtain a first solution; s2: adding anion acceptor Trifluorophenylborane (TPFPB) into the first solution, and fully stirring to fully dissolve the anion acceptor trifluorophenylborane to obtain a second solution; s3: and adding dimethyl carbonate (DMC) into the second solution, and fully stirring until the solution is clear and transparent to obtain the finished electrolyte. The electrolyte with a high DN value has higher cation binding capacity, can effectively increase the solubility of reaction products of the lithium-gas battery, and further reduces the passivation of active sites on a reaction medium, thereby effectively improving the actual specific energy of the lithium-gas battery. The method has the characteristics of simple operation, convenience and quickness, and the prepared electrolyte has excellent electrical property in the aspect of lithium-gas batteries.

Description

A kind of preparation method and electrolyte of high DN value electrolyte applied to lithium-gas battery

technical field

The invention belongs to the technical field of lithium-gas batteries, and in particular relates to a preparation method and an electrolyte of a high DN value electrolyte applied to a lithium-gas battery.

Background technique

Currently, energy systems with high energy density are playing an increasing role in the storage of renewable energies ranging from electric vehicles to wind and solar. Among them, lithium-gas batteries have extremely high energy density. In theory, lithium-gas batteries have a theoretical specific energy of 11140Wh/kg, while lithium-sulfur hexafluoride batteries can achieve a theoretical specific energy of more than 2300Wh/kg. .

However, at present, the actual specific energy of lithium-gas batteries is much lower than the theoretical specific energy. The degree of passivation of the active site by the product is an effective means to improve the actual specific energy of lithium-gas batteries.

Electrolyte with high DN (Donor Number) value, DN value is defined as, in the dilute solution of DN zero non-coordinating solvent 1,2-dichloroethane, Lewis base and standard Lewis acid SbCl 5 (antimony pentachloride) ) negative enthalpy of 1:1 adduct formation. Units are kilocalories per mole (kcal/mol). The DN value is a measure of the ability of a solvent to dissolve cations and Lewis acids. The high DN value electrolyte has high cation binding ability, which can effectively increase the solubility of the reaction product of lithium-gas battery, thereby reducing the passivation of active sites on the reaction medium, thereby effectively improving the actual specific energy of lithium-gas battery.

SUMMARY OF THE INVENTION

The problem to be solved by the present invention is that in the current state of the art, as the reaction progresses, the reaction product of the lithium-gas battery will gradually passivate the active site of the reaction medium, preventing the complete progress of the reaction, and the actual specific energy is much lower than the theoretical specific energy. Therefore, a preparation method and an electrolyte of a high DN value electrolyte for lithium-gas batteries are provided. In turn, the passivation of active sites on the reaction medium is reduced, thereby effectively increasing the actual specific energy of the lithium-gas battery.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

A preparation method of a high DN value electrolyte applied to a lithium-gas battery, comprising the steps of:

S1: dissolving lithium perchlorate in dimethyl sulfoxide (DMSO), fully stirring to make it fully dissolved, to obtain a first solution;

S2: adding the anion acceptor tripentafluorophenylborane (TPFPB) to the first solution, and fully stirring to fully dissolve it to obtain a second solution;

S3: Add dimethyl carbonate (DMC) to the second solution, and fully stir until clear and transparent to obtain a finished electrolyte.

Further, in the step S1, the concentration of the lithium perchlorate is 0.8-1.2M.

Further, in the step S2, the concentration of the anion acceptor tripentafluorophenylborane (TPFPB) is 0.05-0.1M.

Further, the volume ratio of the dimethyl carbonate (DMC) to the dimethyl sulfoxide (DMSO) is 1:4-1:6.

Further, in the step S1, the stirring rotation speed is the first rotation speed, the first rotation speed is 200-400 r/min, the stirring time is T1, and 0.5h≤T1≤1h.

Further, in the step S2, the stirring speed is the second speed, the second speed is 400-600r/min, the stirring time is T2, 0.5h≤T2≤1h.

Further, in the step S3, the stirring speed is the third speed, the third speed is 100-200r/min, and the stirring time is T3, 1h≤T3≤2h.

Further, the lithium perchlorate, the dimethyl sulfoxide (DMSO), the anion acceptor tripentafluorophenylborane (TPFPB), and the dimethyl carbonate (DMC) are all ultra-dry level.

Further, the steps S1, S2 and S3 are all performed in a glove box, and the oxygen concentration and water concentration of the glove box are both less than 0.01 ppm.

A high DN value electrolyte applied to a lithium-gas battery, the high DN value electrolyte applied to the lithium-gas battery is composed of the high DN value electrolyte applied to the lithium-gas battery as described in any one of the above. Preparation method obtained.

The present invention designs a method for preparing a high DN value electrolyte for use in a lithium-gas battery and the electrolyte solution. The high DN value electrolyte has a higher cation binding capacity and can effectively increase the solubility of the lithium-gas battery reaction product. In turn, the passivation of active sites on the reaction medium is reduced, thereby effectively increasing the actual specific energy of the lithium-gas battery.

Description of drawings

Fig. 1 is the photograph of the high DN value electrolyte solution of an embodiment of the present invention at 25 ℃ and 0 ℃;

2 is a discharge curve at 25°C after the high DN value electrolyte and 1M LiPF ₆ -EC/DMC electrolyte according to an embodiment of the present invention are respectively injected into the lithium-sulfur hexafluoride battery;

3 is a discharge curve at 25° C. after the high DN value electrolyte and the 1M LiPF ₆ -EC/DMC electrolyte according to an embodiment of the present invention are respectively injected into the lithium-gas battery;

Fig. 4 is the high DN value electrolyte of an embodiment of the present invention and 1M LiPF ₆ -EC/DMC electrolyte respectively injected into the lithium-sulfur hexafluoride battery fully discharged SEM picture of the positive electrode; Fig. 4 (a) is 1M LiPF ₆ -EC/DMC electrolyte, Figure 4(b) is a high DN value electrolyte.

Detailed ways

The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention and should not be construed as limiting the present invention.

Referring to accompanying drawings 1 to 4, an embodiment of the present invention provides a preparation method of a high DN value electrolyte applied to a lithium-gas battery, comprising the steps of:

S1: dissolving lithium perchlorate in dimethyl sulfoxide (DMSO), fully stirring to make it fully dissolved, to obtain a first solution;

S2: adding the anion acceptor tripentafluorophenylborane (TPFPB) to the first solution, and fully stirring to fully dissolve it to obtain a second solution;

S3: Add dimethyl carbonate (DMC) to the second solution, and fully stir until clear and transparent to obtain a finished electrolyte.

Specifically, dimethyl sulfoxide (DMSO) is selected as the solvent, which has a high DN value and dielectric constant, which can effectively reduce the passivation of the electrochemical reaction product to the active site, promote the continuous progress of the reaction, and improve the reaction efficiency. Actual specific energy: Lithium perchlorate has a very high degree of dissociation, which ensures the full dissociation of lithium ions and the high conductivity of the electrolyte. The anion acceptor tripentafluorophenylborane (TPFPB) has a higher AN value, which increases the AN value of the electrolyte system, further promotes the dissolution of reaction products, and reduces the degree of passivation of active sites. Dimethyl carbonate (DMC) further reduces the melting point of the electrolyte and expands the application temperature range of the electrolyte system.

Specifically, lithium perchlorate, dimethyl sulfoxide (DMSO), anion acceptor tripentafluorophenylborane (TPFPB), and dimethyl carbonate (DMC) used in the experiments were all ultra-dry grades. The ultra-dry grade is packaged with less than 50 ppm of water, has a low water content, and fully reacts with lithium ions as a very high-purity organic solvent.

Specifically, steps S1, S2 and S3 are all performed in a glove box, and the oxygen concentration and water concentration of the glove box are both less than 0.01 ppm, forming a vacuum environment.

Example 1:

S1: Dissolve lithium perchlorate in dimethyl sulfoxide (DMSO), fully stir to fully dissolve it, and obtain a first solution; the first rotation speed is 200r/min, and T1 is 1h, so that it is fully dissolved, and the solution It is clear and transparent, and the concentration of lithium perchlorate is 0.8M.

S2: Add the anion acceptor tripentafluorophenylborane (TPFPB) to the first solution, stir well to fully dissolve it, and obtain the second solution; the second rotation speed is 400r/min, and T2 is 1h to make it fully Dissolved, the solution was clear and transparent, and the concentration of TFPPB was 0.05M.

S3: Add dimethyl carbonate (DMC) to the second solution, and fully stir until it is clear and transparent to obtain a finished electrolyte; the third rotating speed is 100r/min, and T3 is 2h, until the solution has no stratification and is clear and transparent , the volume ratio of dimethyl carbonate (DMC) to dimethyl sulfoxide (DMSO) is 1:4.

Both lithium-gas batteries and lithium-sulfur hexafluoride batteries were assembled and tested using common lithium-gas battery experimental battery devices.

Experimental results:

The high DN value electrolyte prepared in Example 1 has a relatively low melting point and remains in a liquid state at 0°C, as shown in Figure 1;

Figure 1 is a photo of the high DN value electrolyte prepared in Example 1 at 25°C and 0°C. It can be seen from the photo that the electrolyte is liquid at 25°C and 0°C.

The high DN value electrolyte prepared in Example 1 has excellent electrochemical performance in lithium-sulfur hexafluoride batteries. Compared with traditional 1MLiPF ₆ -EC/DMC, it has excellent electrochemical performance when discharged at a current density of 0.5A/g. Higher specific capacity, as shown in Figure 2;

It can be seen from Figure 2 that the high DN value electrolyte has a higher specific capacity in the lithium-sulfur hexafluoride battery than the traditional electrolyte, which is mainly because the high DN value electrolyte has a high cation binding capacity, which can Effectively combines Li+, thereby increasing the solubility of LiF, reducing the passivation of the active site of the positive electrode, and effectively improving the discharge specific capacity of the lithium-sulfur hexafluoride battery.

The high DN value electrolyte prepared in Example 1 has excellent electrochemical performance in lithium-gas batteries, and is higher than the traditional 1M LiPF ₆ -EC/DMC when discharged at a current density of 0.25 A/g. specific capacity, as shown in Figure 3;

It can be seen from Figure 3 that the high DN value electrolyte has a higher specific capacity in the lithium-gas battery than the traditional electrolyte, which is mainly because the high DN value electrolyte can effectively improve the solubility of the discharge intermediate LiO ₂ , In turn, the precipitation mode of the final product Li ₂ O ₂ is affected, from the surface adsorption route to the solvent route, which reduces the degree of passivation of active sites and improves the actual discharge specific capacity.

Fig. 4 is the SEM picture of the positive electrode after the high DN value electrolyte prepared in Example 1 and the 1M LiPF ₆ -EC/DMC electrolyte were respectively injected into the lithium-sulfur hexafluoride battery after full discharge. It can be seen from the picture that the corresponding high DN value The crystal size of LiF on the positive electrode plate of the DN electrolyte is larger and the distribution is more sparse than that of LiF on the positive electrode plate of the corresponding LiPF ₆ electrolyte, which further proves the solubility of LiF in the electrolyte with high DN value.

Example 2:

S1: Dissolve lithium perchlorate in dimethyl sulfoxide (DMSO), fully stir to fully dissolve to obtain a first solution; the first rotation speed is 350r/min, T1 is 0.6h, so that it is fully dissolved, The solution was clear and transparent, and the concentration of lithium perchlorate was 1M.

S2: Add the anion acceptor tripentafluorophenylborane (TPFPB) to the first solution, stir well to fully dissolve it, and obtain the second solution; the second rotation speed is 550r/min, and T2 is 1h to make it fully Dissolved, the solution was clear and transparent, and the concentration of TFPPB was 0.08M.

S3: Add dimethyl carbonate (DMC) to the second solution, and fully stir until it becomes clear and transparent to obtain a finished electrolyte; the third rotating speed is 150r/min, and T3 is 1.5h, until the solution has no stratification and is clear Transparent, the volume ratio of dimethyl carbonate (DMC) to dimethyl sulfoxide (DMSO) is 1:5.

Example 3:

S1: Dissolve lithium perchlorate in dimethyl sulfoxide (DMSO), fully stir to fully dissolve it, and obtain the first solution; the first rotation speed is 400r/min, T1 is 0.7h, so that it is fully dissolved, The solution was clear and transparent, and the concentration of lithium perchlorate was 1.2M.

S2: Add the anion acceptor tripentafluorophenylborane (TPFPB) to the first solution, stir well to fully dissolve it, and obtain the second solution; the second rotation speed is 600r/min, and T2 is 0.5h, so that Fully dissolved, the solution is clear and transparent, and the concentration of TFPPB is 0.1M.

S3: add dimethyl carbonate (DMC) to the second solution, and fully stir until it is clear and transparent to obtain a finished electrolyte; the third rotating speed is 200r/min, and T3 is 1h, until the solution has no layering phenomenon and is clear and transparent , the volume ratio of dimethyl carbonate (DMC) to dimethyl sulfoxide (DMSO) is 1:6.

Example 4:

S1: Dissolve lithium perchlorate in dimethyl sulfoxide (DMSO), fully stir to fully dissolve to obtain a first solution; the first rotation speed is 400r/min, T1 is 0.5h, so that it is fully dissolved, The solution was clear and transparent, and the concentration of lithium perchlorate was 1.2M.

S2: Add the anion acceptor tripentafluorophenylborane (TPFPB) to the first solution, stir well to fully dissolve it, and obtain the second solution; the second rotation speed is 600r/min, and T2 is 0.5h, so that Fully dissolved, the solution was clear and transparent, and the concentration of TFPPB was 0.08M.

S3: add dimethyl carbonate (DMC) to the second solution, and fully stir until it is clear and transparent to obtain a finished electrolyte; the third rotating speed is 200r/min, and T3 is 1h, until the solution has no layering phenomenon and is clear and transparent , the volume ratio of dimethyl carbonate (DMC) to dimethyl sulfoxide (DMSO) is 1:6.

The high DN value electrolytes prepared in Examples 2-4 are consistent with the electrolyte solutions obtained in Example 1 in chemical composition, and the physical properties and electrochemical properties are basically the same.

The advantages and beneficial effects that the present invention produces are:

The present invention designs a preparation method and an electrolyte for a high DN value electrolyte for use in a lithium-gas battery. The high DN value electrolyte of the present invention effectively improves the electrolytic solution by selecting a solvent with a high DN value and an anion acceptor. The DN value and AN value of the liquid system enhance the solubility of the electrolyte system for discharge products and reduce the degree of passivation of active sites. At the same time, the introduction of high dissociation lithium salt and DMC ensures the high conductivity and Wide temperature application range.

It should be understood that the above-mentioned specific embodiments of the present invention are only used to illustrate or explain the principle of the present invention, but not to limit the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the protection scope of the present invention. Furthermore, the appended claims of this invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalents of such scope and boundaries.

Claims (10)

1. a preparation method that is applied to the high DN value electrolyte of lithium-gas battery, is characterized in that, comprises the steps: S1: dissolving lithium perchlorate in dimethyl sulfoxide (DMSO), fully stirring to make it fully dissolved, to obtain a first solution; S2: adding the anion acceptor tripentafluorophenylborane (TPFPB) to the first solution, and fully stirring to fully dissolve it to obtain a second solution; S3: Add dimethyl carbonate (DMC) to the second solution, and fully stir until clear and transparent to obtain a finished electrolyte. 2. a kind of preparation method that is applied to the high DN value electrolyte solution of lithium-gas battery according to claim 1 is characterized in that: In the step S1, the concentration of the lithium perchlorate is 0.8-1.2M. 3. a kind of preparation method that is applied to the high DN value electrolyte of lithium-gas battery according to claim 1 and 2 is characterized in that: In the S2 step, the concentration of the anion acceptor tripentafluorophenylborane (TPFPB) is 0.05-0.1M. 4. a kind of preparation method that is applied to the high DN value electrolyte of lithium-gas battery according to claim 3 is characterized in that: The volume ratio of the dimethyl carbonate (DMC) to the dimethyl sulfoxide (DMSO) is 1:4-1:6. 5. a kind of preparation method that is applied to the high DN value electrolyte of lithium-gas battery according to claim 1 or 2 or 4, is characterized in that: In the step S1, the stirring speed is the first speed, the first speed is 200-400 r/min, the stirring time is T1, 0.5h≤T1≤1h. 6. a kind of preparation method that is applied to the high DN value electrolyte of lithium-gas battery according to claim 5 is characterized in that: In the step S2, the stirring speed is the second speed, the second speed is 400-600r/min, and the stirring time is T2, 0.5h≤T2≤1h. 7. a kind of preparation method that is applied to the high DN value electrolyte of lithium-gas battery according to claim 1 or 2 or 4 or 6, is characterized in that: In the step S3, the stirring speed is the third speed, the third speed is 100-200 r/min, and the stirring time is T3, where 1h≤T3≤2h. 8. a kind of preparation method that is applied to the high DN value electrolyte of lithium-gas battery according to claim 7 is characterized in that: The lithium perchlorate, the dimethyl sulfoxide (DMSO), the anion acceptor tripentafluorophenylborane (TPFPB), and the dimethyl carbonate (DMC) are all ultra-dry grades. 9. a kind of preparation method that is applied to the high DN value electrolyte of lithium-gas battery according to claim 1 or 2 or 4 or 6 or 8, is characterized in that: The steps S1, S2 and S3 are all performed in a glove box, and the oxygen concentration and water concentration of the glove box are both less than 0.01 ppm. 10. A high DN value electrolyte that is applied to a lithium-gas battery, characterized in that: The high DN value electrolyte applied to the lithium-gas battery is prepared by the preparation method of the high DN value electrolyte solution applied to the lithium-gas battery according to any one of claims 1-9.

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