阅读说明：本技术 一种可用于锂电池聚合物固态电解质的聚离子液体的制备方法 (Preparation method of polyion liquid for lithium battery polymer solid electrolyte ) 是由 赵经纬 黄志辉 何天贤 种发瑞 于 2019-11-25 设计创作，主要内容包括：本发明提供一种聚芳醚酮离子液体的制备方法。本发明通过接枝共聚对聚芳醚酮(PAEK)进行改性,提高其溶解性,同时引入离子液体基团,提高PAEK的离子电导率,使其可用作高温锂电池固态电解质。本发明工艺简单,得到的PAEK聚合物电解质(固态电解质)在200℃仍保持很好的力学性能和离子电导率,能够使锂电池正常工作,显著提高了锂电池的使用温度。(The invention provides a preparation method of polyaryletherketone ionic liquid. The invention improves the solubility of the PAEK by modifying the graft poly (aryl ether ketone) (PAEK), and simultaneously introduces the ionic liquid group to improve the ionic conductivity of the PAEK, so that the PAEK can be used as the solid electrolyte of the high-temperature lithium battery. The method has simple process, and the obtained PAEK polymer electrolyte (solid electrolyte) still keeps good mechanical property and ionic conductivity at 200 ℃, so that the lithium battery can normally work, and the use temperature of the lithium battery is obviously improved.)

1. A preparation method of polyaryletherketone polyion liquid comprises the following steps:

(1) adding diphenyl sulfone, a monomer A, a monomer B and carbonate into a reaction kettle, heating and reacting for 3-10 hours under the protection of nitrogen, cooling to obtain a blocky solid, crushing, washing with acetone and water respectively, and drying in vacuum to obtain copolymerized polyaryletherketone; wherein the monomer A is selected from one or more of hydroquinone and derivatives thereof, bisphenol A and derivatives thereof, and bisphenol fluorene and derivatives thereof in any proportion; the monomer B is selected from one or more bifluoro-substituted benzophenones in any proportion; the molar ratio of the monomer A to the monomer B is A: B = 0.95-1.05: 1, and the molar ratio of the monomer A to the carbonate is A: carbonate =1: 1-1.2;

(2) adding the copolymerized polyaryletherketone obtained in the step (1) into CHCl₃Introducing chlorine or dropwise adding bromine water, keeping the temperature of a reaction system to be lower than 50 ℃, adding methanol for precipitation after the reaction is finished, filtering, and drying to obtain halogenated copolymerized polyaryletherketone;

(3) dissolving the halogenated copolymerization polyaryletherketone prepared in the step (2) in a solvent C, adding an ionizing reagent D under the protection of nitrogen, stirring for reaction at 30-70 ℃, adding methanol for precipitation after the reaction is finished, filtering, and drying to obtain a polyaryletherketone polyion liquid precursor; wherein the solvent C is selected from one or more of Dimethylformamide (DMF), dimethylacetamide (DMAc) and Tetrahydrofuran (THF); the ionizing reagent D is selected from one or more of N-containing five-membered or six-membered heterocyclic compounds and derivatives thereof in any proportion;

(4) dissolving the polyaryletherketone polyion liquid precursor prepared in the step (3) in a solvent C, and adding KPF₆Or stirring and reacting an aqueous solution of lithium bis (trifluoromethane sulfonyl) imide (LiTFSI) at 20-60 ℃ for 3 hours, filtering after the reaction is finished, and drying in vacuum at 40 ℃ to obtain the polyaryletherketone polyion liquid.

2. The preparation method of claim 1, wherein the nitrogen protection means that nitrogen is introduced into the reaction system until the oxygen content is less than 5 ppm.

3. The preparation method according to claim 1, wherein in the step (1), the monomer A is selected from one or more of 2-methyl hydroquinone, 2-ethyl hydroquinone, 2-tert-butyl hydroquinone, 2-methyl bisphenol A, 2-tert-butyl bisphenol A, 2-ethyl bisphenol A and bisphenol fluorene in any ratio;

preferably, in the step (1), the monomer B is 4, 4' -difluorobenzophenone.

4. The production method according to claim 1 or 3, wherein in the step (1), the temperature raising procedure for the reaction of the monomer A and the monomer B is: heating to 140 ℃ for reaction for 1h, reacting at 180 ℃ for 1h, reacting at 220 ℃ for 2h, and heating to 300-330 ℃ at a speed of 10-20 ℃/min for reaction for 1 h.

5. The process according to claim 1, wherein in the step (1), after the reaction is completed, a solid in the form of a block is obtained, pulverized, and washed with acetone and water 3 times, respectively.

6. The method according to claim 1, wherein in step (1), the copolymerized polyaryletherketone is dried under vacuum at 150 ℃ for 12 h.

7. The method according to claim 1, wherein in the step (3), the ionizing agent is one or two selected from imidazole and pyridine at any ratio.

8. A polyaryletherketone polyionic liquid prepared by the preparation method of any one of claims 1 to 7.

9. The use of a polyaryletherketone polyionic liquid of claim 8 in the preparation of a solid electrolyte;

specifically, the application comprises the steps of dissolving the polyaryletherketone polyionic liquid by using one or more solvents selected from methyl pyrrolidone, dimethylformamide and dimethylacetamide in any proportion to prepare an electrolyte membrane, and absorbing the electrolyte to swell so as to obtain the solid electrolyte.

10. A solid electrolyte comprising an electrolyte membrane prepared from the polyaryletherketone polyionic liquid of claim 8 and an electrolyte adsorbed by the electrolyte membrane.

Technical Field

The invention belongs to the technical field of polymer chemistry and lithium batteries, and particularly relates to a preparation method of polyion liquid for a lithium battery polymer solid electrolyte and the polyion liquid prepared by the preparation method.

Background

With the development of new energy automobiles and the popularization of electronic products, the development of lithium batteries is receiving wide attention, and high energy density and high safety become the key development direction of lithium batteries. A currently used lithium battery structurally includes a positive electrode, a negative electrode, a separator, and a liquid electrolyte interposed between the positive and negative electrodes. The liquid electrolyte is an indispensable important component of the lithium battery and is a necessary condition for the lithium battery to obtain the advantages of high voltage, high cycle performance and the like. Although the liquid electrolyte is beneficial to improving the conductivity and the wettability of the electrode, the liquid electrolyte also has the defects of poor electrochemical stability, flammability and easy volatilization; in case of a lithium battery generating a high temperature or a spark due to an internal short circuit, the liquid electrolyte is instantaneously ignited and causes explosion of the entire battery. The solid electrolyte has the advantages of high safety performance, high energy density and strong cycle performance. The experts believe that the replacement of the traditional liquid electrolyte with the solid electrolyte is a necessary way to essentially improve the safety of the lithium battery.

Solid electrolytes are mainly classified into two types: inorganic solid electrolytes and polymer solid electrolytes. The inorganic solid electrolyte is generally a lithium composite oxide or sulfide, and has high ionic conductivity, high cost, high interface resistance and high processing difficulty. The polymer electrolyte mainly includes polyethylene glycol (PEO), Polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), Polycarbonate (PC), polymethyl methacrylate (PMMA), and the like. The polymers have certain ionic conductivity after being treated by blending, copolymerization, surface modification, ionic liquidation and the like, and can be used as polymer solid electrolytes. The ionic liquid can effectively improve the ionic conductivity of the polymer and is more beneficial to enhancing the performance of the solid electrolyte. For example, the invention patent application of publication No. CN104103874A (published 2014, 10, 15) of 'a preparation method and application of a polyion liquid-based solid electrolyte' discloses a polyion liquid solid electrolyte prepared by ion exchange of polyvinyl imidazole and spiro quaternary ammonium tetrafluoroborate. Chinese patent application publication No. CN108899212A (published 2018, 11, 27) of 'preparation method and application of ternary polyion liquid-based solid electrolyte' discloses a solid electrolyte comprising 20-60 wt% of polyion liquid, 2-60 wt% of ionic liquid and 2-30 wt% of alkali metal salt; the polyion liquid is selected from dimethyl diallyl ammonium chloride and 1-butyl-3-vinylImidazole bromide, homopolymers of 1-butyl-3- (1-vinylimidazole-3-hexyl) -imidazole bromide and the like, and alkali metal salts; the ionic liquid is solid gel electrolyte ionic liquid and is selected from one of N-methyl-N-propyl pyrrolidine bis (trifluoromethanesulfonyl) imide (Py13TFSI), N-methyl-N-propyl piperidine bis (trifluoromethanesulfonyl) imide (PP13TFSI), N-methyl-N-butyl pyrrolidine bis (trifluoromethanesulfonyl) imide (PY14TFSI), 1-methyl-3-ethylimidazole bis (trifluoromethanesulfonyl) imide (EMITFSI) and the like; the alkali metal salt is selected from lithium bis (trifluoromethyl) sulfonimide (LiTFSI) and potassium hexafluorophosphate (KPF)₆) Sodium bis (trifluoromethyl) sulfonimide (NaTFSI), sodium perchlorate (NaClO)₄) Sodium hexafluorophosphate (NaPF)₆) And sodium difluorosuccinimide (NaFSI). However, when the polymer such as PEO, PAN, PVDF, PC, PMMA has a linear structure with a main chain structure similar to alkane, the use temperature is not high, and the polymer is severely shrunk or has poor mechanical properties when used at the temperature of more than 150 ℃, so that the polymer cannot be used continuously.

The PAEK has excellent heat resistance, can still maintain excellent mechanical property at 260 ℃, and has feasibility of being used as a solid electrolyte of a high-temperature lithium battery.

Disclosure of Invention

Aiming at the existing defects, the invention provides a preparation method of polyaryletherketone ionic liquid. The invention improves the solubility of the PAEK by modifying the graft poly (aryl ether ketone) (PAEK), and simultaneously introduces the ionic liquid group to improve the ionic conductivity of the PAEK, so that the PAEK can be used as the solid electrolyte of the high-temperature lithium battery. The method has simple process, and the obtained PAEK polymer electrolyte (solid electrolyte) still keeps good mechanical property and ionic conductivity at 200 ℃, so that the lithium battery can normally work, and the use temperature of the lithium battery is obviously improved.

In order to achieve the technical effects, the invention adopts the following technical scheme:

a preparation method of polyaryletherketone polyion liquid comprises the following steps:

(1) adding diphenyl sulfone, a monomer A, a monomer B and carbonate into a reaction kettle, heating and reacting for 3-10 hours under the protection of nitrogen, cooling to obtain a blocky solid, crushing, washing with acetone and water respectively, and drying in vacuum to obtain copolymerized polyaryletherketone; wherein the monomer A is selected from one or more of hydroquinone and derivatives thereof, bisphenol A and derivatives thereof, and bisphenol fluorene and derivatives thereof in any proportion; the monomer B is selected from one or more bifluoro-substituted benzophenones in any proportion; the molar ratio of the monomer A to the monomer B is A: B = 0.95-1.05: 1, and the molar ratio of the monomer A to the carbonate is A: carbonate =1: 1-1.2;

(2) adding the copolymerized polyaryletherketone obtained in the step (1) into CHCl₃Introducing chlorine or dropwise adding bromine water, keeping the temperature of a reaction system to be lower than 50 ℃, adding methanol for precipitation after the reaction is finished, filtering, and drying to obtain halogenated copolymerized polyaryletherketone;

(3) dissolving the halogenated copolymerization polyaryletherketone prepared in the step (2) in a solvent C, adding an ionizing reagent D under the protection of nitrogen, stirring for reaction at 30-70 ℃, adding methanol for precipitation after the reaction is finished, filtering, and drying to obtain a polyaryletherketone polyion liquid precursor; wherein the solvent C is selected from one or more of Dimethylformamide (DMF), dimethylacetamide (DMAc) and Tetrahydrofuran (THF); the ionizing reagent D is selected from one or more of N-containing five-membered or six-membered heterocyclic compounds and derivatives thereof in any proportion;

(4) dissolving the polyaryletherketone polyion liquid precursor prepared in the step (3) in a solvent C, and adding KPF₆Or stirring and reacting an aqueous solution of lithium bis (trifluoromethane sulfonyl) imide (LiTFSI) at 20-60 ℃ for 3 hours, filtering after the reaction is finished, and drying in vacuum at 40 ℃ to obtain the polyaryletherketone polyion liquid.

Preferably, the nitrogen protection means that nitrogen is introduced into the reaction system until the oxygen content is less than 5 ppm.

Preferably, in the step (1), the monomer A is selected from one or more of 2-methyl hydroquinone, 2-ethyl hydroquinone, 2-tert-butyl hydroquinone, 2-methyl bisphenol A, 2-tert-butyl bisphenol A, 2-ethyl bisphenol A and bisphenol fluorene in any proportion.

Preferably, in the step (1), the monomer B is 4, 4' -difluorobenzophenone.

Preferably, in the step (1), the temperature rising procedure of the reaction of the monomer A and the monomer B is as follows: heating to 140 ℃ for reaction for 1h, reacting at 180 ℃ for 1h, reacting at 220 ℃ for 2h, and heating to 300-330 ℃ at a speed of 10-20 ℃/min for reaction for 1 h.

Preferably, in the step (1), after the reaction is completed, a solid block is obtained, pulverized, and washed with acetone and water 3 times, respectively.

Preferably, in the step (1), the copolymerized polyaryletherketone is dried for 12 hours in vacuum at 150 ℃.

Preferably, in the step (3), the ionizing agent is selected from one or two of imidazole and pyridine at any ratio.

The invention also aims to provide the polyaryletherketone polyionic liquid prepared by the preparation method.

In addition, the invention also provides application of the polyaryletherketone polyionic liquid in preparation of a solid electrolyte.

Specifically, the application comprises the step of dissolving the polyaryletherketone polyionic liquid in one or more solvents selected from methylpyrrolidone (NMP), Dimethylformamide (DMF) and dimethylacetamide (DMAc) in any proportion to prepare an electrolyte membrane, and the electrolyte membrane absorbs electrolyte to swell so as to obtain the solid electrolyte.

The invention also provides a solid electrolyte, which comprises an electrolyte membrane prepared from the polyaryletherketone polyionic liquid and electrolyte adsorbed by the electrolyte membrane.

The main chain of the pure PAEK is a benzene ring structure, so the PAEK is insoluble in an organic solvent and has poor wetting property. According to the invention, a copolymerization method is adopted to introduce side groups into the PAEK, so that the electron cloud density of a benzene ring is reduced, the rigidity of the PAEK is reduced, and the dissolving capacity of the PAEK for infiltrating an organic solvent is improved, so that the PAEK is dissolved or swelled in some organic solvents, and the subsequent chemical reaction modification is facilitated.

Br or Cl is introduced into a benzene ring and a side group of the PAEK by halogenating the PAEK. Part of Br or Cl can react with an ionizing reagent (such as imidazole and the like) to form an ionic liquid, and the other part of Br or Cl is beneficial to enhancing the organic solubility of the PAEK even if the Br or Cl is not reacted due to steric hindrance or other factors.

The invention further reacts PAEK polyion liquid precursor with PF₆ ^-Or TFSI^-Replacement of Cl^-Or Br^-And the stability, the conductivity and the electrochemical window of the obtained polyion liquid are further improved.

In conclusion, the beneficial effects of the invention are as follows:

the PAEK polyion liquid with the main chain of a benzene ring structure obtained by the preparation method provided by the invention has better organic solubility, ionic conductivity and high temperature resistance. The electrolyte can be used as a polymer solid electrolyte of a lithium battery, can be used for a long time at the temperature of more than 200 ℃, and greatly improves the use temperature of the polymer solid electrolyte.

Detailed Description

The present invention is further illustrated by the following examples. However, the present invention is not limited to the following examples.

The raw materials, reagents, equipment, instruments and the like used in the following examples are commercially available without specific reference.