阅读说明：本技术 一种基于聚偏氟乙烯和强碱的固态电解质薄膜及其制备方法 (Solid electrolyte film based on polyvinylidene fluoride and strong base and preparation method thereof ) 是由 刘一阳 傅裕 毛焕宇 刘贯东 龙赛夫 于 2020-04-14 设计创作，主要内容包括：本发明提供了一种基于聚偏氟乙烯和强碱的固态电解质薄膜,其包括以下组分：固体的聚偏氟乙烯、有机溶剂、锂盐和强碱。该固态电解质薄膜的制备方法包括以下制备步骤：1)将聚偏氟乙烯加入有机溶剂中,搅拌30-60分钟,得到第一溶液；2)将锂盐和强碱固体加入第一溶液中,搅拌10-20分钟,得到第二溶液；3)将第二溶液均匀涂敷在基底表面,置于至少90℃的鼓风烘箱中,烘烤30-60分钟,随后从基底上揭下并得到固态电解质薄膜。本发明所提供的一种基于聚偏氟乙烯和强碱的固态电解质薄膜及其制备方法相较于现有技术具有室温下高离子电导率和良好的机械强度的优点。(The invention provides a solid electrolyte film based on polyvinylidene fluoride and strong base, which comprises the following components: solid polyvinylidene fluoride, organic solvent, lithium salt and strong base. The preparation method of the solid electrolyte film comprises the following preparation steps: 1) adding polyvinylidene fluoride into an organic solvent, and stirring for 30-60 minutes to obtain a first solution; 2) adding lithium salt and strong base solid into the first solution, and stirring for 10-20 minutes to obtain a second solution; 3) and uniformly coating the second solution on the surface of the substrate, placing the substrate in a blast oven at the temperature of at least 90 ℃, baking the substrate for 30-60 minutes, and then removing the substrate to obtain the solid electrolyte film. Compared with the prior art, the solid electrolyte film based on polyvinylidene fluoride and strong base and the preparation method thereof have the advantages of high ionic conductivity and good mechanical strength at room temperature.)

1. A solid electrolyte film based on polyvinylidene fluoride and strong base is characterized by comprising the following components: solid polyvinylidene fluoride, organic solvent, lithium salt and strong base;

the mass ratio of the polyvinylidene fluoride to the organic solvent is (5-20) to (80-95); and the polyvinylidene fluoride and the organic solvent form a first solution;

the mass ratio of the lithium salt to the strong base to the first solution is (0.03-3) to (5-20) to (80-95).

2. The method for preparing a solid electrolyte membrane based on polyvinylidene fluoride and strong base as claimed in claim 1, wherein the polyvinylidene fluoride has a molar mass of 20000-2000000 g/mol.

3. The method for preparing a solid electrolyte membrane based on polyvinylidene fluoride and strong base according to claim 1, wherein the organic solution is one or more of acetone, acetonitrile, tetrahydrofuran, N-N-dimethylformamide, N-N-dimethylacetamide, N-N-dimethylpropionamide, N-methylpyrrolidone, trimethyl phosphate, and triethyl phosphate.

4. The method for preparing a solid electrolyte film based on polyvinylidene fluoride and strong base according to claim 1, wherein the lithium salt is one or more of lithium hexafluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium tetrafluoroborate, lithium dioxalate borate and lithium bistrifluorosulfonylimide.

5. The method for preparing a solid electrolyte membrane based on polyvinylidene fluoride and a strong base according to claim 1, wherein the strong base is one or more of dimethylamine, diethylamine, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, ammonia, sodium hydroxide, lithium hydroxide and potassium hydroxide.

6. The method for preparing a solid electrolyte film based on polyvinylidene fluoride and strong base according to any one of claims 1 to 5, comprising the following preparation steps:

1) adding the polyvinylidene fluoride into the organic solvent, and stirring for 30-60 minutes to obtain the first solution;

2) adding the lithium salt and the strong base solid into the first solution, and stirring for 10-20 minutes to obtain a second solution;

3) and uniformly coating the second solution on the surface of the substrate, placing the substrate in a blast oven at the temperature of at least 90 ℃, baking the substrate for 30-60 minutes, and then removing the substrate to obtain the solid electrolyte film.

Technical Field

The invention relates to the field of batteries, in particular to a solid electrolyte film based on polyvinylidene fluoride and strong base and a preparation method thereof.

Background

The development of the new energy automobile industry is an important national strategy in China, and the new energy automobile currently adopts a lithium ion battery to provide power for the new energy automobile. Lithium ion batteries contain liquid, easily flowable, easily combustible organic solution-based electrolytes. In the charging and discharging process of the battery, the internal short circuit easily causes the energy of the battery to be completely released in a very short time, a large amount of heat energy is generated, and then the liquid electrolyte is ignited, so that safety accidents are caused. In this context, solid-state lithium ion batteries based on solid-state, non-flowable, non-flammable solid-state electrolytes are believed to fundamentally solve the safety problems of new energy vehicles, and are recognized as next-generation lithium ion batteries.

The core component of a solid-state battery is the solid-state electrolyte. The solid electrolyte needs to have high room-temperature ionic conductivity and good chemical stability, does not react with positive and negative electrode materials of the battery, and simultaneously has low manufacturing cost so as to meet the requirement of large-scale production.

Disclosure of Invention

The invention provides a solid electrolyte film based on polyvinylidene fluoride and strong base and a preparation method thereof, wherein a new mode is adopted to improve the ionic conductivity of a polymer, the mode does not depend on the reduction of the crystallinity of the polymer, a new lithium ion binding site is generated through the interaction between the polymer and a strong base group, and lithium ion site holes with adjustable concentration can be obtained in a compound by adjusting the proportion of three substances of poly (vinylidene fluoride), strong base and lithium salt, so that an ion conduction channel is generated. The mechanism of this ionic conductance is different from the traditional segmental oscillating mechanism of polymers, but more similar to the transport mechanism in metal oxides and sulfides, with ionic conductivities several orders of magnitude higher than traditional polymers.

To this end, in one aspect, the present invention provides a solid electrolyte membrane based on polyvinylidene fluoride and a strong base, comprising the following components: solid polyvinylidene fluoride, organic solvent, lithium salt and strong base;

the mass ratio of the polyvinylidene fluoride to the organic solvent is (5-20) to (80-95); and polyvinylidene fluoride and an organic solvent form a first solution;

the mass ratio of the lithium salt to the strong base to the first solution is (0.03-3) to (5-20) to (80-95).

Furthermore, the molar mass of the polyvinylidene fluoride is 20000-2000000 g/mol.

Further, the organic solution is one or more of acetone, acetonitrile, tetrahydrofuran, N-N-dimethylformamide, N-N-dimethylacetamide, N-N-dimethylpropionamide, N-methylpyrrolidone, trimethyl phosphate and triethyl phosphate.

Further, the lithium salt is one or more of lithium hexafluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium tetrafluoroborate, lithium dioxalate borate and lithium bistrifluorosulfonylimide.

Further, the strong base is one or more of dimethylamine, diethylamine, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, ammonia water, sodium hydroxide, lithium hydroxide and potassium hydroxide.

Further, the preparation method of the solid electrolyte film based on polyvinylidene fluoride and strong base comprises the following preparation steps:

1) adding polyvinylidene fluoride into an organic solvent, and stirring for 30-60 minutes to obtain a first solution;

2) adding lithium salt and strong base solid into the first solution, and stirring for 10-20 minutes to obtain a second solution;

3) and uniformly coating the second solution on the surface of the substrate, placing the substrate in a blast oven at the temperature of at least 90 ℃, baking the substrate for 30-60 minutes, and then removing the substrate to obtain the solid electrolyte film.

According to the solid electrolyte film based on polyvinylidene fluoride and strong base and the preparation method thereof, a novel mode is adopted to improve the ionic conductivity of the polymer, the mode does not depend on the reduction of the crystallinity of the polymer, a novel lithium ion binding site is generated through the interaction between the polymer and a strong base group, and lithium ion site holes with adjustable concentration can be obtained in the compound by adjusting the proportion of the three substances of poly (vinylidene fluoride), strong base and lithium salt, so that an ion conduction channel is generated. The mechanism of this ionic conductance is different from the traditional segmental oscillating mechanism of polymers, but more similar to the transport mechanism in metal oxides and sulfides, with ionic conductivities several orders of magnitude higher than traditional polymers.

Therefore, compared with the prior art, the solid electrolyte film based on polyvinylidene fluoride and strong base and the preparation method thereof have the advantages of high ionic conductivity and good mechanical strength at room temperature.

Drawings

Fig. 1 is a graph comparing the conductivity of a solid electrolyte and a conventional polymer electrolyte in a solid electrolyte thin film based on polyvinylidene fluoride and strong base.

Fig. 2 is a charge-discharge graph of lithium iron phosphate using a solid electrolyte in a solid electrolyte thin film based on polyvinylidene fluoride and a strong base.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below. While exemplary embodiments of the present disclosure have been shown, it should be understood that the present disclosure may be embodied in various forms and should not be limited by 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.