CN114899486A - Pyridine-containing non-aqueous electrolyte, preparation method thereof and sodium battery - Google Patents

Abstract

The invention discloses a nonaqueous electrolyte containing pyridine, which comprises a sodium salt, a nonaqueous organic solvent and an additive, wherein the additive is pyridine or acetylpyridine, and the weight percentage content of the additive is 0.5-2.0 wt%. The acetylpyridine is 4-acetylpyridine or 3-acetylpyridine, and the concentration of sodium salt is 1M. The non-aqueous electrolyte containing pyridine, the preparation method thereof and the sodium battery can solve the problems of low coulombic efficiency and few charging and discharging times caused by the fact that metal sodium in the existing sodium metal battery is easy to form dendrites.

Description

A kind of non-aqueous electrolyte containing pyridine and preparation method thereof and sodium battery

technical field

The invention relates to the technical field of sodium batteries, in particular to a pyridine-containing non-aqueous electrolyte, a preparation method thereof, and a sodium battery.

Background technique

With the development of high-power electronic devices such as electric vehicles, traditional batteries have been unable to meet the requirements of their energy density. With high theoretical capacity (1161 mAh g-1), high storage capacity, and outstanding low-temperature performance, sodium metal anode batteries are considered as next-generation batteries with potential for a wide range of applications. However, metal sodium tends to form dendrites and break during repeated deposition and stripping, and easily reacts with the electrolyte to form inactive sodium, thereby reducing the Coulombic efficiency. These problems severely limit the application of sodium metal batteries.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a pyridine-containing non-aqueous electrolyte, which solves the problems that metal sodium easily forms dendrites in existing nano-metal batteries, resulting in low coulombic efficiency and few charging and discharging times. Another object of the present invention is to provide a method for preparing a pyridine-containing non-aqueous electrolyte and a sodium battery containing the pyridine-containing non-aqueous electrolyte.

In order to achieve the above purpose, the present invention provides a pyridine-containing non-aqueous electrolyte, including sodium salt, non-aqueous organic solvent and additive, the additive is pyridine or acetyl pyridine, and the weight percentage of the additive is 0.5-2.0wt %;

乙酰基吡啶为4-乙酰吡啶或3-乙酰吡啶，4-乙酰吡啶的结构式为

3-乙酰吡啶的结构式为

The structural formula of pyridine is

Acetylpyridine is 4-acetylpyridine or 3-acetylpyridine, and the structural formula of 4-acetylpyridine is

The structural formula of 3-acetylpyridine is

Preferably, the concentration of the sodium salt is 1M, and the sodium salt is NaPF ₆ , NaClO ₄ , NaN(SO ₂ CF ₃ ) ₂ , NaN(SO ₂ C ₂ F ₅ ) ₂ , NaC(SO ₂ CF ₃ ) ₃ or One or more mixtures of NaN(SO ₂ F) ₂ .

Preferably, the non-aqueous organic solvent is a mixture of cyclic carbonate and chain carbonate, and the volume ratio of cyclic carbonate and chain carbonate is 3:7-7:3; the cyclic carbonate is One or more mixtures of ethylene carbonate, propylene carbonate or butylene carbonate, and the chain carbonate is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or propyl methyl carbonate. one or a mixture of several.

The preparation method of the above-mentioned pyridine-containing non-aqueous electrolyte, comprises the following steps:

S1. In the glove box, H ₂ O <0.1ppm, O ₂ <0.1ppm, weigh an appropriate amount of sodium salt and dissolve it in a non-aqueous organic solution, the concentration of the sodium salt is 1M, to obtain the base electrolyte;

S2. Add an additive with a mass percentage of 0.5-2.0 wt% in the base electrolyte, and the additive is pyridine or acetylpyridine, and stir evenly to obtain a pyridine-containing non-aqueous electrolyte.

A sodium battery containing the pyridine-containing non-aqueous electrolyte prepared by the above preparation method comprises a battery case, a positive electrode, a negative electrode, a separator and an electrolyte located in the battery case.

Preferably, the positive electrode includes a positive electrode current collector and a positive electrode material located on the positive electrode current collector, and the positive electrode material includes a positive electrode active material; the positive electrode active material is Na ₃ V ₂ (PO ₄ ) ₃ , Na ₃ V ₂ (PO ₄ ) ) ₂ O ₂ F, Prussian blue or a mixture of any of them.

Preferably, the negative electrode includes a negative electrode current collector and a negative electrode material located on the negative electrode current collector, and the negative electrode material is graphite, hard carbon, soft carbon, silicon carbon composite material, silicon oxygen carbon composite material, metal sodium, metal sodium One or a mixture of several alloys.

Preferably, the separator is one or more of polyolefin porous membrane, non-woven fabric, fiber coating, ceramic coating, and inorganic solid electrolyte coating.

In the non-aqueous electrolyte solution containing pyridine, a preparation method thereof, and a sodium battery according to the present invention, the additive contains an electron-withdrawing acetyl group, which can adjust the cation solvation structure in the electrolyte solution and reduce the participation of anions in the solid electrolyte interface. phase (SEI) energy barrier, thereby promoting the degradation of salt on the surface of the metal anode to produce SEI rich in sodium fluoride NaF, with high mechanical strength and high surface energy, which is beneficial to inhibit the growth of sodium dendrites and improve the battery cycle efficiency. Acetylpyridine additives can also form a highly stable catholyte interphase (CEI), improve battery stability, rate and other properties, thereby improving the overall performance of the battery.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the cycle life diagram of the sodium symmetric battery prepared by the implementation electrolyte 1 of the present invention that adopts a kind of pyridine-containing non-aqueous electrolyte and its preparation method and sodium battery;

2 is a cycle life diagram of a sodium symmetric battery prepared by implementing a pyridine-containing non-aqueous electrolyte and a preparation method thereof and a sodium battery according to the present invention;

3 is a cycle life diagram of a sodium symmetric battery prepared by implementing a pyridine-containing non-aqueous electrolyte, a preparation method thereof, and a sodium battery according to the present invention;

4 is a cycle life diagram of a sodium symmetric battery prepared by implementing a pyridine-containing non-aqueous electrolyte, a preparation method thereof, and a sodium battery according to the present invention;

5 is a cycle life diagram of a sodium symmetric battery prepared by implementing a pyridine-containing non-aqueous electrolyte, a preparation method thereof, and a sodium battery according to the present invention;

6 is a cycle life diagram of a sodium symmetric battery prepared by implementing a pyridine-containing non-aqueous electrolyte, a preparation method thereof, and a sodium battery according to the present invention;

7 is a cycle life diagram of a sodium symmetric battery prepared by implementing electrolyte 7 using a pyridine-containing non-aqueous electrolyte and a preparation method thereof and a sodium battery of the present invention;

8 is a cycle life diagram of a sodium symmetric battery prepared by adopting a pyridine-containing non-aqueous electrolyte and a preparation method thereof and the comparative electrolyte 1 of the sodium battery of the present invention;

FIG. 9 is a cycle performance diagram of a full battery prepared with a pyridine-containing non-aqueous electrolyte, a preparation method thereof, and a sodium battery using a pyridine-containing non-aqueous electrolyte 1 of the present invention and a full battery prepared with a comparative electrolyte 1. FIG.

Detailed ways

A pyridine-containing non-aqueous electrolyte includes sodium salt, a non-aqueous organic solvent and an additive, the additive is pyridine or acetylpyridine, and the weight percentage of the additive is 0.5-2.0 wt %.

乙酰基吡啶为4-乙酰吡啶或3-乙酰吡啶，4-乙酰吡啶的结构式为

3-乙酰吡啶的结构式为

The structural formula of pyridine is

Acetylpyridine is 4-acetylpyridine or 3-acetylpyridine, and the structural formula of 4-acetylpyridine is

The structural formula of 3-acetylpyridine is

The additive contains electron-withdrawing acetyl groups, which can adjust the cationic solvation structure in the electrolyte and reduce the energy barrier for anions to participate in the solid electrolyte interphase (SEI), thereby promoting the degradation of salts on the metal anode surface to produce rich sodium fluoride The SEI of NaF has high mechanical strength and high surface energy, which is beneficial to inhibit the growth of sodium dendrites and improve the battery cycle efficiency. Acetylpyridine additives can also form a highly stable catholyte interphase (CEI), improve battery stability, rate and other properties, thereby improving the overall performance of the battery.

The concentration of sodium salt is 1M, and the sodium salt is NaPF ₆ , NaClO ₄ , NaN(SO ₂ CF ₃ ) ₂ , NaN(SO ₂ C ₂ F ₅ ) ₂ , NaC(SO ₂ CF ₃ ) ₃ or NaN(SO ₂ F ) ) ₂ in one or a mixture of several.

The non-aqueous organic solvent is a mixture of cyclic carbonate and chain carbonate, and the volume ratio of cyclic carbonate and chain carbonate is 3:7-7:3; the cyclic carbonate is ethylene carbonate, carbonic acid The mixture of one or more in propylene ester or butylene carbonate, described chain carbonate is one or more in dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate or methyl propyl carbonate mixture. The mixed solution of high dielectric constant cyclic carbonate organic solvent and low viscosity chain carbonate organic solvent is used as the solvent for the electrolyte of sodium ion battery, so that the mixed solution of organic solvent has high ionic conductivity, high Dielectric constant and low viscosity.

The preparation method of the above-mentioned pyridine-containing non-aqueous electrolyte, comprises the following steps:

S1. In the glove box, H ₂ O <0.1ppm, O ₂ <0.1ppm, weigh an appropriate amount of sodium salt and dissolve it in a non-aqueous organic solution, the concentration of the sodium salt is 1M, to obtain a base electrolyte;

S2. Add an additive with a mass percentage of 0.5-2.0 wt% in the base electrolyte, and the additive is pyridine or acetylpyridine, and stir evenly to obtain a pyridine-containing non-aqueous electrolyte.

A sodium battery containing the pyridine-containing non-aqueous electrolyte prepared by the above preparation method comprises a battery case, a positive electrode, a negative electrode, a separator and an electrolyte located in the battery case.

The positive electrode includes a positive electrode current collector and a positive electrode material located on the positive electrode current collector, the positive electrode material includes a positive electrode active material; the positive electrode active material is Na ₃ V ₂ (PO ₄ ) ₃ , Na ₃ V ₂ (PO ₄ ) ₂ O ₂ F , Prussian blue, or a mixture of any of them.

The negative electrode includes a negative electrode current collector and a negative electrode material located on the negative electrode current collector, and the negative electrode material is one of graphite, hard carbon, soft carbon, silicon carbon composite material, silicon oxycarbon composite material, metal sodium, and an alloy of metal sodium. or a mixture of several.

The separator is one or more of polyolefin porous membrane, non-woven fabric, fiber coating, ceramic coating, and inorganic solid electrolyte coating.

The technical solutions of the present invention will be further described below through the accompanying drawings and embodiments.

Example 1

In a glove box (H ₂ O<0.1ppm, O ₂ <0.1ppm), weigh an appropriate amount of sodium hexafluorophosphate (NaPF ₆ ) and dissolve it in a non-aqueous organic solution to obtain a base electrolyte.

Sodium salt concentration: 1M sodium hexafluorophosphate;

Non-aqueous organic solvent: mixed solvent of ethylene carbonate (EC): diethyl carbonate (DEC)=1:1 (v:v);

A compound represented by 3-acetylpyridine in a mass fraction of 1.0 wt % was added to the base electrolyte, and the electrolyte solution 1 was obtained after stirring uniformly.

Example 2

The electrolyte solution was prepared by the method described in Example 1, except that 1.0 wt% pyridine was added to the base electrolyte solution to obtain the implementation electrolyte solution 2.

Example 3

The electrolyte solution was prepared by the method described in Example 1, except that 4-acetylpyridine with a mass fraction of 1.0 wt% was added to the base electrolyte solution to obtain the implementation electrolyte solution 3.

Example 4

The electrolyte solution was prepared by the method described in Example 1, except that 3-acetylpyridine with a mass fraction of 0.5 wt% was added to the base electrolyte solution to obtain the implementation electrolyte solution 4.

Example 5

The electrolyte solution was prepared by the method described in Example 1, except that 3-acetylpyridine with a mass fraction of 2.0 wt% was added to the base electrolyte solution to obtain the implementation electrolyte solution 5.

Example 6

Adopt the method described in Example 1 to configure the electrolyte, the difference is that in the base electrolyte, the mixed solvent ratio of ethylene carbonate (EC): diethyl carbonate (DEC) is 3:7 (v:v), and the implementation of Electrolyte 6.

Example 7

Adopt the method described in Example 1 to configure the electrolyte, the difference is that in the base electrolyte, the mixed solvent ratio of ethylene carbonate (EC): diethyl carbonate (DEC) is 7:3 (v:v), and the implementation of Electrolyte 7.

Comparative Example 1

Comparative Example The base electrolyte prepared by the method described in Example 1 was used as Comparative Electrolyte 1.

Sodium batteries were prepared using the above-described implementation electrolytes 1-7 and comparative electrolyte 1.

The preparation method of sodium battery is as follows:

Sodium symmetric battery: in the glove box (H ₂ O <0.1ppm, O ₂ <0.1ppm), sequentially connect the positive electrode shell → sodium sheet → electrolyte → separator → electrolyte → sodium sheet → stainless steel gasket → negative electrode shell from the bottom Assembled above, and then transferred to a tablet press for stamping and packaging to obtain a finished sodium symmetric battery.

Full battery: In the glove box (H ₂ O <0.1ppm, O ₂ <0.1ppm), sequentially connect the positive shell → FNVP pole piece → electrolyte → separator → electrolyte → sodium plate → stainless steel gasket → spring plate → negative electrode The case is assembled from the bottom up, and then transferred to a tablet press for stamping and packaging to obtain a completed full cell.

The electrochemical performance of the assembled battery was tested by Xinwei test equipment. The specific experimental process is as follows: the sodium sheet is used as the positive and negative electrodes to assemble a sodium symmetric battery for constant current charge-discharge test; the sodium sheet is used as the negative electrode, and FNVP (Na ₃ V ₂ (PO ₄ ) ₂ O ₂ F) is used as the positive electrode activity materials, matched and assembled into a full battery for galvanostatic charge-discharge test.

Fig. 1 is the cycle life diagram of the sodium symmetric battery prepared by adopting a kind of pyridine-containing non-aqueous electrolyte solution of the present invention, its preparation method and sodium battery, and Fig. 2 is a kind of pyridine-containing non-aqueous electrolyte solution according to the present invention. Electrolyte and its preparation method and implementation of sodium battery The cycle life diagram of the sodium symmetric battery prepared by electrolyte 2, FIG. 3 is a non-aqueous electrolyte containing pyridine of the present invention and its preparation method and implementation electrolyte of sodium battery. 3. The cycle life diagram of the prepared sodium symmetric battery, and FIG. 8 is the cycle life diagram of the sodium symmetric battery prepared by using a pyridine-containing non-aqueous electrolyte of the present invention and its preparation method and the comparative electrolyte 1 of the sodium battery. As shown in the figure, the sodium symmetric battery prepared with the implementation of electrolyte 1 can make the battery cycle more than 360 hours after the polarization degree is still small, the sodium symmetric battery prepared with the implementation of the electrolyte 2 can make the battery cycle more than 120 hours after polarization The degree is still small, and the sodium symmetric battery prepared by implementing electrolyte 3 can make the degree of polarization still small after the battery is cycled for more than 150 hours. The sodium symmetric battery prepared with Comparative Electrolyte 1 showed severe polarization after 100 hours of cycling. Therefore, adding 3-acetylpyridine to the electrolyte can effectively prolong the cycle life of sodium symmetric batteries. Adding 4-acetylpyridine or pyridine to the electrolyte slightly improved the cycle life of sodium symmetric batteries.

4 is a cycle life diagram of a sodium symmetric battery prepared by using a pyridine-containing non-aqueous electrolyte of the present invention, a preparation method thereof, and a sodium battery, and FIG. 5 is a pyridine-containing non-aqueous electrolyte of the present invention. Electrolyte and its preparation method and implementation of sodium battery Cycle life diagram of sodium symmetric battery prepared by electrolyte 5. As shown in the figure, the degree of polarization is still small after cycling the sodium symmetric battery in electrolyte 4 for more than 180 hours, and the cycle life of the sodium symmetric battery is increased. After the sodium symmetric battery in electrolyte 5 is cycled for more than 380 hours, the polarization degree is still small, and the cycle life of the sodium symmetric battery is greatly increased. By changing the concentration of 3-acetylpyridine additive in the electrolyte, the cycle life of the obtained sodium symmetric battery is better extended.

6 is a cycle life diagram of a sodium symmetric battery prepared using a kind of pyridine-containing non-aqueous electrolyte of the present invention, a preparation method thereof, and the implementation of electrolyte 6 of the sodium battery, and FIG. 7 is a diagram of a pyridine-containing non-aqueous electrolyte of the present invention. Electrolyte solution and its preparation method and implementation of sodium battery Cycle life diagram of sodium symmetric battery prepared by electrolyte solution 7. As shown in the figure, under the condition of different proportions of non-aqueous organic solvent, 3-acetylpyridine additive can still significantly prolong the cycle life of sodium symmetric battery.

FIG. 9 is a cycle performance diagram of a full battery prepared with a pyridine-containing non-aqueous electrolyte, a preparation method thereof, and a sodium battery using a pyridine-containing non-aqueous electrolyte 1 of the present invention and a full battery prepared with a comparative electrolyte 1. FIG. As shown in the figure, the cycle stability of the full battery assembled with the implementation of electrolyte 1 is greatly improved, the capacity retention rate of 91.0% is still maintained after 200 cycles, the specific capacity decay is relatively slow, and the average Coulomb efficiency reaches 97%. .

Therefore, the present invention adopts the above-mentioned pyridine-containing non-aqueous electrolyte and its preparation method and sodium battery, which can solve the problems that metal sodium easily forms dendrites in the existing nano-metal battery, resulting in low coulombic efficiency and few charging and discharging times.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still The technical solutions of the present invention may be modified or equivalently replaced, and these modifications or equivalent replacements cannot make the modified technical solutions depart from the spirit and scope of the technical solutions of the present invention.

Claims (8)

1. A pyridine-containing nonaqueous electrolytic solution characterized in that: comprises sodium salt, non-aqueous organic solvent and additive, wherein the additive is pyridine or acetylpyridine, and the weight percentage content of the additive is 0.5-2.0 wt%;

the structural formula of pyridine is

The acetylpyridine is 4-acetylpyridine or 3-acetylpyridine, and the structural formula of the 4-acetylpyridine is shown in the specification

The structural formula of the 3-acetylpyridine is shown in the specification

2. The nonaqueous electrolytic solution containing pyridine of claim 1, wherein: the concentration of the sodium salt is 1M, and the sodium salt is NaPF ₆ 、NaClO ₄ 、NaN(SO ₂ CF ₃ ) ₂ 、NaN(SO ₂ C ₂ F ₅ ) ₂ 、NaC(SO ₂ CF ₃ ) ₃ Or NaN (SO) ₂ F) ₂ One or a mixture of several of them.

3. The nonaqueous electrolytic solution containing pyridine of claim 1, wherein: the non-aqueous organic solvent is a mixture of cyclic carbonate and chain carbonate, and the volume ratio of the cyclic carbonate to the chain carbonate is 3:7-7: 3; the cyclic carbonate is one or a mixture of more of ethylene carbonate, propylene carbonate or butylene carbonate, and the chain carbonate is one or a mixture of more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or propyl methyl carbonate.

4. The method for preparing a nonaqueous electrolytic solution containing pyridine according to any one of claims 1 to 3, characterized by comprising the steps of:

s1, in a glove box, H ₂ O<0.1ppm，O ₂ <0.1ppm, weighing a proper amount of sodium salt, and dissolving the sodium salt in a nonaqueous organic solution, wherein the concentration of the sodium salt is 1M, so as to obtain a substrate electrolyte;

s2, adding 0.5-2.0 wt% of additive into the base electrolyte, wherein the additive is pyridine or acetylpyridine, and uniformly stirring to obtain the pyridine-containing nonaqueous electrolyte.

5. A sodium battery containing the pyridine-containing nonaqueous electrolytic solution prepared in claim 4, characterized in that: comprises a battery shell, a positive electrode, a negative electrode, a diaphragm and electrolyte which are positioned in the battery shell.

6. The sodium battery of claim 5, wherein: the positive electrode comprises a positive electrode current collector and a positive electrode material positioned on the positive electrode current collector, wherein the positive electrode material comprises a positive electrode active material; the positive electrode active material is Na ₃ V ₂ (PO ₄ ) ₃ 、Na ₃ V ₂ (PO ₄ ) ₂ O ₂ F. One or a mixture of any more than one of the Prussian blue.

7. The sodium battery of claim 5, wherein: the negative electrode comprises a negative electrode current collector and a negative electrode material positioned on the negative electrode current collector, wherein the negative electrode material is one or a mixture of more of graphite, hard carbon, soft carbon, a silicon-carbon composite material, a silicon-oxygen-carbon composite material, metal sodium and an alloy of the metal sodium.

8. The sodium battery of claim 5, wherein: the diaphragm is one or more of polyolefin porous membrane, non-woven fabric, fiber coating, ceramic coating and inorganic solid electrolyte coating.

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