Preparation method of solid-state polyphosphazene-based ionic conductor

Abstract

The invention relates to a preparation method of a solid-state polyphosphazene-based ionic conductor. The preparation method comprises the following steps: reacting alkoxy ether salt, unsaturated phenate and a self-made dichlorophosphazene polymer to obtain an ether phosphazene polymer (MEGP) with high solvation ability; and mixing and copolymerizing the product with an acrylate derivative, a lithium salt and an initiator to obtain the solid polyphosphazene-based ionic conductor (SPPPBIC). The ionic conductor has good ionic conductivity, tensile property and flame retardant property, and can meet normal long-term use requirements and safety requirements. In the invention, the copolymerization reaction of the MEGP and the acrylate derivative does not need additional solvent addition and post-treatment, and the preparation method has the characteristics of simple process, quick reaction and no pollution. In addition, the related performance of the SPPBIC can be adjusted by changing the reaction ratio of the MEGP to the acrylate derivative, and different application requirements can be met.

Description

Technical field:

[0001] The invention belongs to the field of polymer electrolytes, and in particular relates to a synthesis preparation method of a solid polyphosphazene-based ion conductor and an application thereof. Technical background:

[0002] Linear polydichlorophosphazene has the characteristics of low glass transition temperature, flexible chain and rich P and N flame retardant elements. Ether oxygen groups are introduced into the side groups to obtain ether oxygen substituted polyphosphazene. This ether oxygen polyphosphazene reacts with Li + The formation of coordination bonds is expected to give it conductivity and stability to the metal anode. Regarding the research reports on phosphazene electrolytes, for example, CN113278189A published a method for preparing a flame-retardant gel electrolyte based on in-situ polymerization: Wang Xiufen et al. used sodium trifluoroethoxide and sodium 2-[2-(vinyloxy)ethoxy]ethoxide to react with hexachlorocyclotriphosphazene to prepare cyclophosphazene (TFV) containing multiple carbon-carbon double bond functional groups, and polymerized TFV with butyl acrylate under the condition of adding electrolyte to obtain an electrolyte. The prepared electrolyte has a high electrochemical window, ion migration number and good flame retardant properties; in the literature (Peter M. Blonsky, DF Shrive. et al. Polyphosphazene Solid Electrolytes. Journal of Materials Chemistry A, 1984, 106: 6854-6855), Allcock synthesized poly (diethylene glycol monomethyl ether) phosphazene and added lithium salt to prepare a polyphosphazene electrolyte with conductivity, but the prepared electrolyte has poor tensile properties and is difficult to meet the needs of long-term use. The present invention aims to prepare a solid polyphosphazene-based ion conductor (SPPBIC) with good electrical conductivity and tensile properties. Summary of the invention:

[0003] The present invention adopts a mixed copolymerization method to prepare SPPBIC to obtain an ion conductor with good conductivity and tensile properties to meet the needs of long-term use. To achieve the above purpose, the technical solution of the present invention is as follows:

[0004] (1) Preparation of crude ether phosphazene polymer (MEGP): reacting alkoxy ether salt, unsaturated phenol salt and self-made dichlorophosphazene polymer for 24 to 48 hours. After the reaction, centrifugation and precipitation are performed to obtain crude MEGP product.

[0005] (2) Purification of crude MEGP product: Distilled water and dilute hydrochloric acid are added to the crude product until the solution becomes neutral. The crude product is then phase-separated and purified at a certain temperature and dried to obtain polymer MEGP.

[0006] (3) Preparation of an ion conductor precursor solution: MEGP, an acrylate derivative, a lithium salt and an initiator are mixed in a certain molar ratio and stirred to obtain an ion conductor precursor solution.

[0007] (4) Synthesis of SPPBIC: The above-mentioned uniformly mixed ion conductor precursor solution is copolymerized to obtain SPPBIC.

[0008] The advantages of the present invention are as follows:

[0009] (1) The prepared SPPBIC has good ionic conductivity, tensile properties and flame retardant properties, meeting normal long-term use needs and safety requirements.

[0010] (2) The copolymerization reaction of MEGP and acrylate derivatives does not require the addition of additional solvents and post-treatment, and the preparation method has the characteristics of simple process, rapid reaction and no pollution.

[0011] (3) The relevant properties of SPPBIC can be adjusted by changing the reaction ratio of MEGP and acrylate derivatives to meet different application requirements. Specific implementation method:

[0012] In order to better understand the present invention, the content of the present invention is further explained in conjunction with the following examples, but the content of the present invention is not limited to the following examples, and the examples should not be regarded as limiting the scope of protection of the present invention.

[0013] Implementation Case 1:

[0014] (1) Preparation of crude MEGP product: Sodium diethylene glycol monomethyl ether and sodium eugenol were placed in a three-necked flask and reacted with a self-made dichlorophosphazene polymer for 48 hours, wherein the molar ratio of sodium diethylene glycol monomethyl ether, sodium eugenol and the self-made dichlorophosphazene polymer was 1:5.67:2.7. After the reaction was completed, the crude MEGP product was obtained by centrifugation and precipitation.

[0015] (2) Purification of crude MEGP: The crude product was placed in a beaker, and distilled water and 1 mol / L dilute hydrochloric acid were added until the solution was neutral. The crude product solution was then subjected to phase separation and purification in an oil bath at 70°C. The purified product was dried in a vacuum oven to obtain the polymer MEGP.

[0016] (3) Preparation of an ion conductor precursor solution: MEGP, hydroxyethyl acrylate, LiTFSI and dimethyl benzoate were mixed in a molar ratio of 1:11:0.6:0.03 and stirred to obtain an ion conductor precursor solution.

[0017] (4) Synthesis of SPPBIC: The uniformly mixed ion conductor precursor solution was copolymerized under ultraviolet light for 10 min to obtain SPPBIC.

[0018] (5) According to GB / T 528-92, a type 2 dumbbell-shaped specimen cutter was used to cut the sample into strips to test its tensile properties. The tensile strength of the SPPBIC strips was 1.4 MPa and the elongation at break was 463%. SPPBIC was prepared in situ in the battery shell and the battery was encapsulated to test its ionic conductivity. The ionic conductivity of SPPBIC was 9.4×10 -6 S cm -1 .

[0019] Implementation Case 2:

[0020] (1) Preparation of crude MEGP product: Sodium diethylene glycol monomethyl ether and sodium eugenol were placed in a three-necked flask and reacted with a self-made dichlorophosphazene polymer for 48 hours, wherein the molar ratio of sodium diethylene glycol monomethyl ether, sodium eugenol and the self-made dichlorophosphazene polymer was 1:5.67:2.7. After the reaction was completed, the crude MEGP product was obtained by centrifugation and precipitation.

[0021] (2) Purification of crude MEGP product: The crude product was placed in a beaker, and distilled water and 1 mol / L dilute hydrochloric acid were added until the solution was neutral. The crude product solution was then subjected to phase separation and purification in an oil bath at 80°C. The purified product was dried in a vacuum oven to obtain the polymer MEGP.

[0022] (3) Preparation of an ion conductor precursor solution: MEGP, hydroxyethyl acrylate, LiTFSI and dimethyl benzoate were mixed in a molar ratio of 1:11:0.3:0.03 and stirred to obtain an ion conductor precursor solution.

[0023] (4) Synthesis of SPPBIC: The uniformly mixed ion conductor precursor solution was copolymerized under ultraviolet light for 10 min to obtain SPPBIC.

[0024] (5) According to GB / T 528-92, a type 2 dumbbell-shaped specimen cutter was used to cut the sample into strips to test its tensile properties. The tensile strength of the SPPBIC strips was 1.2 MPa and the elongation at break was 451%. SPPBIC was prepared in situ in the battery shell and the battery was packaged to test its ionic conductivity. The ionic conductivity of SPPBIC was 3.5×10 -6 S cm -1

[0025] Implementation Case 3:

[0026] (1) Preparation of crude MEGP product: Sodium diethylene glycol monomethyl ether and sodium eugenol were placed in a three-necked flask and reacted with a self-made dichlorophosphazene polymer for 48 hours, wherein the molar ratio of sodium diethylene glycol monomethyl ether, sodium eugenol and the self-made dichlorophosphazene polymer was 1:5.67:2.7. After the reaction was completed, the crude MEGP product was obtained by centrifugation and precipitation.

[0027] (2) Purification of crude MEGP product: The crude product was placed in a beaker, and distilled water and 1 mol / L dilute hydrochloric acid were added until the solution was neutral. The crude product solution was then subjected to phase separation and purification in an oil bath at 75°C. The purified product was dried in a vacuum oven to obtain the polymer MEGP.

[0028] (3) Preparation of an ion conductor precursor solution: MEGP, hydroxyethyl acrylate, LiTFSI and dimethyl benzoate were mixed in a molar ratio of 1:9:0.3:0.03 and stirred to obtain an ion conductor precursor solution.

[0029] (4) Synthesis of SPPBIC: The uniformly mixed ion conductor precursor solution was copolymerized under ultraviolet light for 10 min to obtain SPPBIC.

[0030] (5) According to GB / T 528-92, the sample was made into a strip using a type 2 dumbbell-shaped specimen cutter to test its tensile properties. The tensile strength of the SPPBIC strip was 1.2 MPa and the elongation at break was 423%. SPPBIC was prepared in situ in the battery shell and the battery was encapsulated to test its ionic conductivity. The ionic conductivity of SPPBIC was 2.2×10 -6 S cm -1 .

[0031] Implementation Case 4:

[0032] (1) Preparation of crude MEGP product: Sodium diethylene glycol monomethyl ether and sodium eugenol were placed in a three-necked flask and reacted with a self-made dichlorophosphazene polymer for 48 hours, wherein the molar ratio of sodium diethylene glycol monomethyl ether, sodium eugenol and the self-made dichlorophosphazene polymer was 1:5.67:2.7. After the reaction was completed, the crude MEGP product was obtained by centrifugation and precipitation.

[0033] (2) Purification of crude MEGP: The crude product was placed in a beaker, and distilled water and 1 mol / L dilute hydrochloric acid were added until the solution was neutral. The crude product solution was then subjected to phase separation and purification in an oil bath at 70°C. The purified product was dried in a vacuum oven to obtain the polymer MEGP.

[0034] (3) Preparation of an ion conductor precursor solution: MEGP, hydroxyethyl acrylate, LiTFSI and dimethyl benzoate were mixed in a molar ratio of 1:9:0.15:0.03 and stirred to obtain an ion conductor precursor solution.

[0035] (4) Synthesis of SPPBIC: The uniformly mixed ion conductor precursor solution was copolymerized under ultraviolet light for 10 min to obtain SPPBIC.

[0036] (5) According to GB / T 528-92, the sample was made into a strip using a type 2 dumbbell-shaped specimen cutter to test its tensile properties. The tensile strength of the SPPBIC strip was 1.1 MPa and the elongation at break was 386%. SPPBIC was prepared in situ in the battery shell and the battery was encapsulated to test its ionic conductivity. The ionic conductivity of SPPBIC was 9.3×10 -6 S cm -1 .

Claims

1. A method for preparing a solid polyphosphazene-based ion conductor, the main steps of which are as follows: (1) Preparation of crude ether phosphazene polymer (MEGP): reacting alkoxy ether salt, unsaturated phenol salt and self-made dichlorophosphazene polymer for 24 to 48 hours. After the reaction, centrifugation and precipitation are performed to obtain crude MEGP product. (2) Purification of crude MEGP product: Distilled water and dilute hydrochloric acid are added to the crude product until the solution becomes neutral. The crude product is then phase-separated and purified at a certain temperature and dried to obtain polymer MEGP. (3) Preparation of an ion conductor precursor solution: MEGP, an acrylate derivative, a lithium salt and an initiator are mixed in a certain molar ratio and stirred to obtain an ion conductor precursor solution. (4) Synthesis of solid polyphosphazene-based ion conductor (SPPBIC): The above-mentioned uniformly mixed ion conductor precursor solution is copolymerized to obtain SPPBIC.

2. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: In the step (1), the alkoxy ether salt includes but is not limited to diethylene glycol monomethyl ether salt, triethylene glycol monomethyl ether salt, tetraethylene glycol monomethyl ether salt, pentaethylene glycol monomethyl ether salt, and diethylene glycol monomethyl ether salt is preferred in the present invention.

3. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: In the step (1), the unsaturated phenolate is a derivative of p-allyl phenolate, and the structural formula is as follows, wherein R1 is -H, -CH3, -OCH3, -OCH2CH3, -OCH2CH2OCH3; M is Li, Na, K, and in the present invention, R1 is preferably -OCH3; and M is preferably Na.

4. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: In the step (1), the molar ratio of the alkoxy ether salt to the unsaturated phenol salt is 3:1 to 15:1, and is preferably 5.6:1 in the present invention.

5. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: In the step (2), the experimental temperature for the purification of the crude MEGP product is controlled to be 50°C to 90°C. The experimental temperature for the purification of the crude MEGP product is preferably 80°C.

6. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: In the step (3), the molar ratio of MEGP to the acrylate derivative is 1:1 to 1:100, and 1:11 is preferred in the present invention.

7. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: In the step (3), the structural formula of the acrylate derivative is as follows, wherein R2 is -H, -CH3, -CH2CH3, -CH2CH2CH3, -CH2CH2CH2CH3, -CH2CH2OH, -CH2CH2CH2OH, -CH2CH2OCH3, -CH2CH2CH2CH2CH2CH3(CH3), -CH2CH2OCH2CH2OCH2CH3, and -CH2CH2OH is preferred in the present invention.

8. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: In the step (3), the lithium salt includes but is not limited to LiClO4, LiCl, LiBF4, LiAsF6, LiPF6, and LiTFSI, and LiTFSI is preferred in the present invention.

9. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: In the step (4), the mixed copolymerization reaction of the ion conductor precursor solution can be either a thermal polymerization reaction or an ultraviolet (UV) polymerization reaction, wherein the initiator used in the thermal polymerization reaction includes azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide, and methyl ethyl ketone peroxide; the initiator used in the UV polymerization reaction includes benzophenones, benzoin and its derivatives, benzil, acylphosphine oxides, thioxanthones, and alkyl phenones. In the present invention, benzoin and its derivative benzoin dimethyl ether are preferably used as the UV polymerization initiator.

10. The method for preparing a solid polyphosphazene-based ion conductor according to claim 1, characterized in that: The structural formula of the prepared SPPBIC is shown below.

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