阅读说明：本技术 一种聚酯类嵌段共聚物、其一锅法合成方法及应用 (Polyester block copolymer, one-pot synthesis method and application thereof ) 是由 薛志刚 郭楷瑞 李少桥 王计嵘 周兴平 解孝林 于 2021-07-13 设计创作，主要内容包括：本发明属于锂离子电池聚合物电解质领域,更具体地,涉及一种聚酯类嵌段共聚物、其一锅法合成方法和应用。本发明提出的一锅法合成聚酯类嵌段共聚物基聚合物电解质的方法,通过选择合适的反应单体,配合采用合适的双官能化链转移试剂和自由基引发剂,可在一锅中结合可逆加成-断裂转移聚合与环内酯开环聚合反应,更加方便快捷,绿色高效地合成分子量可控且其分布较窄的聚酯类嵌段共聚物。本发明提出的一锅法合成聚酯类嵌段共聚物基电解质的方法,为合成兼具优异机械强度和电化学性能的固态聚合物电解质材料提供新思路。(The invention belongs to the field of lithium ion battery polymer electrolytes, and particularly relates to a polyester block copolymer, a one-pot synthesis method and application thereof. The method for synthesizing the polyester block copolymer-based polymer electrolyte by the one-pot method provided by the invention can combine reversible addition-fragmentation transfer polymerization and cyclic lactone ring-opening polymerization reaction in one pot by selecting a proper reaction monomer and adopting a proper bifunctional chain transfer reagent and a proper free radical initiator, so that the polyester block copolymer with controllable molecular weight and narrow distribution can be synthesized more conveniently, quickly, greenly and efficiently. The method for synthesizing the polyester block copolymer-based electrolyte by the one-pot method provided by the invention provides a new idea for synthesizing a solid polymer electrolyte material with excellent mechanical strength and electrochemical performance.)

1. A method for preparing a polyester-based block copolymer, comprising the steps of:

(1) under the anhydrous and anaerobic conditions, uniformly mixing a styrene monomer, a cyclic lactone monomer and a poly (ethylene glycol) methacrylate monomer to form a monomer mixture;

(2) mixing the monomer mixture obtained in the step (1) with a free radical initiator 4,4' -azobis (4-cyanovaleric acid) and a chain transfer reagent 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol to obtain a raw material mixed solution;

(3) heating the raw material mixed solution obtained in the step (2) in an inert atmosphere to enable the monomer to perform reversible addition-fragmentation transfer polymerization and cyclic lactone ring-opening polymerization reaction; after the reaction is finished, cooling to room temperature to quench the reaction to obtain a crude product, and separating to obtain the polyester block copolymer.

2. The method of claim 1, wherein the cyclic lactone monomer is one or more of epsilon-caprolactone, delta-valerolactone, DL-lactide, and trimethylene carbonate.

3. The method as claimed in claim 1, wherein the molar ratio of the styrene monomer, the cyclic lactone monomer, the poly (ethylene glycol) methacrylate monomer and the chain transfer agent is 100-200:300-600:30-70: 1.

4. The method according to claim 1, wherein the molar ratio of the radical initiator to the chain transfer agent is 1:3 to 1: 5.

5. The preparation method according to claim 1, wherein in the step (3), the temperature is increased to 50-90 ℃ for reaction for 12-36 hours to allow the styrene monomer and the poly (ethylene glycol) methacrylate monomer to undergo reversible addition-fragmentation transfer polymerization, and then the temperature is increased to 110-150 ℃ for reaction for 16-48 hours to allow the cyclic lactone monomer to undergo ring-opening polymerization.

6. The polyester-based block copolymer produced by the production process according to any one of claims 1 to 5.

7. The use of the polyester-based block copolymer according to claim 6 for preparing an electrolyte membrane of a lithium ion battery.

8. The use according to claim 7, wherein the electrolyte membrane has a thickness of 50 to 100 microns.

9. The use according to claim 7, wherein the electrolyte membrane is prepared by the following method: dissolving the polyester block copolymer and lithium salt in a solvent according to the mass ratio of the polymer to the lithium salt of 2: 1-7: 1 to obtain a mixed solution, and then preparing the polymer electrolyte membrane by adopting a solution casting method.

10. The use according to claim 7, wherein the solvent is one or more of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N-dimethylformamide and dimethylsulfoxide; the lithium salt is one or more of bis (trifluoromethyl) sulfonyl imide lithium, lithium perchlorate and lithium hexafluorophosphate.

Technical Field

The invention belongs to the field of lithium ion battery polymer electrolytes, and particularly relates to a polyester block copolymer, a one-pot synthesis method and application thereof.

Background

Polyester compounds (e.g., polycarbonates and polyesters) include C ═ O bonds and C — O bonds, both of which coordinate and dissociate with lithium ions, and ester groups with large dipole moments enhance dissociation of lithium salts and promote migration of lithium ions in the polymer matrix, thereby increasing the lithium ion migration number. Compared with the traditional polyether polymer, the polyester polymer has more environmental friendliness, biocompatibility and thermal stability. In addition, polyester-based electrolytes have better anode stability to high-pressure environments during lithium ion transport. Therefore, the polyester-based polymer used as the matrix of the all-solid-state lithium ion battery has a wider working range, and can provide good cycle performance for the all-solid-state battery based on the polyester-based electrolyte (J.energy. chem.2021,52, 318-) -325). However, the special soft segment and semi-crystallinity of the polyester polymer cause poor mechanical properties and room temperature ion conductivity of the polyester electrolyte, and the practical application requirements of the lithium ion battery are difficult to meet.

In order to solve the problem, scientists propose a series of means of constructing grafting, crosslinking, copolymerization, block and hyperbranched structures and the like to reduce the semicrystalline of the polyester compound, so as to effectively improve the electrochemical performance and the mechanical performance of the polyester polymer electrolyte. For example, Bowden et al reported a diblock copolymer all solid state electrolyte based on poly (benzyl methacrylate) -poly (. epsilon. -caprolactone-r-trimethylene carbonate) (ACS appl.Polym.Mater.2020,2, 939-. Wherein, the polymethyl benzyl acrylate is used as a hard segment, the mechanical strength of the electrolyte is obviously improved, and the storage modulus of the electrolyte at 40 ℃ is 0.2 GPa; poly(s) are polymerizedCopolymers of caprolactone and polytrimethylene carbonate provide excellent ion conductivity as amorphous soft segments. The all-solid electrolyte membrane has an ionic conductivity of 9.1X 10 at 30 DEG C^-6S/cm, the transference number of lithium ions can reach 0.64. Therefore, the electrochemical performance and the mechanical performance of the polyester polymer electrolyte can be effectively improved by constructing a topological structure. However, the synthesis of polyester-based copolymers usually needs to be achieved by a step-feed method, for example, the south university of science and technology dang Yonghong task group prepares polycaprolactone and polystyrene hyperbranched copolymer electrolytes (J.electrochem. Soc.2020,167,110532) based on azide-alkyne click chemistry, but the hyperbranched copolymer still needs to synthesize polystyrene precursors and polycaprolactone precursors with different molecular weights respectively. Denoyel et al prepared a polystyrene-polyoxyethylene-polystyrene triblock polymer electrolyte (Macromolecules 2014,47, 2659) -2665), and a bifunctional polyoxyethylene macroinitiator also needs to be synthesized in the preparation process, so that a synthesis method which is simple and convenient to operate and controllable in reaction is urgently needed to be developed for preparing a polyester copolymer based electrolyte.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for preparing a polyester block copolymer electrolyte by a one-pot method, and aims to solve the technical problems that the polyester block copolymer electrolyte in the prior art needs to be realized by a step-by-step feeding method, the preparation method is complex, the reaction is uncontrollable and the like.

In order to achieve the above object, the present invention provides a method for preparing a polyester-based block copolymer, comprising the steps of:

(1) under the anhydrous and anaerobic conditions, uniformly mixing a styrene monomer, a cyclic lactone monomer and a poly (ethylene glycol) methacrylate monomer to form a monomer mixture;

(2) mixing the monomer mixture obtained in the step (1) with a free radical initiator 4,4' -azobis (4-cyanovaleric acid) and a chain transfer reagent 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol to obtain a raw material mixed solution;

(3) and (3) heating the raw material mixed solution obtained in the step (2) in an inert atmosphere to enable the monomer to perform reversible addition-fragmentation transfer polymerization and cyclic lactone ring-opening polymerization reaction, cooling to room temperature after the reaction is finished, quenching the reaction to obtain a crude product, and separating to obtain the polyester block copolymer.

In a preferred embodiment, the cyclic lactone monomer is one or more of epsilon-caprolactone, delta-valerolactone, DL-lactide and trimethylene carbonate.

The polyester block copolymer comprises a hard segment structure formed by a polystyrene chain segment, and a soft segment structure formed by poly (ethylene glycol) methacrylate and a polyester chain segment; the polyester chain segment is one or more of polycaprolactone, polypentanolactone, polylactide and polytrimethylene carbonate; the polymerization degree ratio of the polystyrene chain segment to the poly (ethylene glycol) methacrylate chain segment is 100: 30-200: 70; the polymerization degree ratio of the polystyrene chain segment to the polyester chain segment is 100: 300-200: 600. taking the polyester chain segment as polycaprolactone (the cyclic lactone monomer in the step (1) is epsilon-caprolactone) as an example, the polyester block copolymer-based polymer electrolyte has a structure shown as the formula (I):

wherein r is an integer of 30 to 70, n is an integer of 100 to 200, and m is an integer of 300 to 600;

as a further preferred aspect of the present invention, the polyester-based block copolymer represented by the formula (I) has a synthetic route represented by the formula (II):

wherein r is an integer of 30 to 70, n is an integer of 100 to 200, and m is an integer of 300 to 600. St (4) represents a styrene monomer, CL (5) represents a caprolactone monomer, PEGMA475(6) represents a poly (ethylene glycol) methacrylate monomer having a molecular weight of 475, and ACVA (2) represents a radical initiator 4,4' -azobis (4-cyanovaleric acid).

Preferably, the terminal of the 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol in step (2) contains hydroxyl, which can be used as a chain transfer reagent and an initiator of a ring-opening reaction at the same time, the trithiocarbonate structure can catalyze styrene monomer to perform reversible addition-fragmentation transfer polymerization, the terminal hydroxyl initiates cyclic lactone monomer to perform ring-opening polymerization, and the two polymerization reactions can be realized by a one-pot method; the structural formula of the bifunctional chain transfer reagent is shown as (III):

preferably, the free radical initiator 4,4' -azobis (4-cyanovaleric acid) (abbreviated as ACVA) in step (2) is difunctional, which acts both as a free radical initiator and as a catalyst for the ring-opening reaction of the cyclic lactone; the structural formula of the bifunctional free radical initiator is shown as (IV):

in a preferable scheme, the feeding molar ratio of the styrene monomer, the cyclic lactone monomer, the poly (ethylene glycol) methacrylate monomer and the chain transfer agent is 100-200:300-600:30-70: 1.

In a preferable scheme, the feeding molar ratio of the free radical initiator to the chain transfer reagent is 1: 3-1: 5.

In a preferable scheme, in the step (3), firstly, the temperature is increased to 50-90 ℃ for reaction for 12-36 hours, so that reversible addition-fragmentation transfer polymerization is performed on vinyl monomers (the styrene monomers and the poly (ethylene glycol) methacrylate monomers), and then the temperature is increased to 110-150 ℃ for reaction for 16-48 hours, so that ring-opening polymerization reaction is performed on the cyclic lactone monomers.

In a preferred scheme, after the crude product is obtained in the step (3), tetrahydrofuran is adopted to dissolve the crude product to obtain a block copolymer solution; then adding the obtained block copolymer solution into anhydrous ether for precipitation, filtering and separating precipitate, and drying to obtain the polyester block copolymer.

In a preferable embodiment, the inert atmosphere in the step (3) is an argon atmosphere or a nitrogen atmosphere.

According to another aspect of the present invention, there is provided a polyester-based block copolymer prepared by the above-mentioned preparation method.

According to another aspect of the present invention, there is provided a use of the polyester-based block copolymer for preparing an electrolyte membrane of a lithium ion battery.

In a preferred embodiment, the thickness of the electrolyte membrane is 50 to 100 μm.

In a preferred embodiment, the electrolyte membrane is prepared by the following method: dissolving the polyester block copolymer and lithium salt in a solvent according to the mass ratio of the polymer to the lithium salt of 2: 1-7: 1 to obtain a mixed solution, and then preparing the polymer electrolyte membrane by adopting a solution casting method.

In a preferred scheme, the solvent is one or more of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N-dimethylformamide and dimethyl sulfoxide; the lithium salt is one or more of bis (trifluoromethyl) sulfonyl imide lithium, lithium perchlorate and lithium hexafluorophosphate.

Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

(1) the invention provides a method for synthesizing polyester block copolymer-based polymer electrolyte by a one-pot method, which can combine reversible addition-fragmentation transfer polymerization and cyclic lactone ring-opening polymerization reaction in one pot by selecting proper reaction monomers and adopting proper bifunctional chain transfer reagents and free radical initiators, thereby synthesizing the polyester block copolymer with controllable molecular weight and narrow distribution in a more convenient and rapid environment-friendly and efficient way. The method for synthesizing the polyester block copolymer-based electrolyte by the one-pot method provided by the invention provides a new idea for synthesizing a solid polymer electrolyte material with excellent mechanical strength and electrochemical performance.

(2) The invention introduces a bifunctional chain transfer reagent 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol and a bifunctional radical initiator 4,4 '-azobis (4-cyanovaleric acid) in the one-pot preparation process of the polyester block copolymer electrolyte, and simultaneously utilizes the characteristic that organic acid in the 4,4' -azobis (4-cyanovaleric acid) can catalyze hydroxyl to initiate ring opening reaction of cyclic lactone, so that the one-pot preparation of the polyester block copolymer electrolyte becomes possible. Compared with the traditional ring-opening polymerization reaction, the organic metal catalyst has lower toxicity and structural stability, and overcomes the defect of metal residue of the traditional catalyst.

(3) The invention designs and synthesizes the polyester block copolymer-based electrolyte. The electrolyte combines the advantages of the mechanical strength and the electrochemical performance of the two blocks, overcomes the defect of low mechanical strength of the polyester polymer, simultaneously inhibits the semicrystalline of the polyester polymer, and enhances the room-temperature ion conduction capability of the polyester polymer.

(4) The invention firstly applies the one-pot synthesis polyester block copolymer to the field of electrolyte, and compared with the traditional polyester electrolyte, the polyester block copolymer has a controllable structure, can flexibly adjust the type and length of two blocks, and combines the advantages of the two blocks to obtain the polymer electrolyte material meeting the practical application.

Drawings

FIG. 1 is a flow chart of the one-pot method for preparing the polyester block copolymer electrolyte.

FIG. 2 is a nuclear magnetic resonance spectrum of the polyester-based block copolymer synthesized in example 1 of the present invention.

FIG. 3 is a graph showing the outflow of the polyester-based block copolymer synthesized in example 1 of the present invention.

Fig. 4 is a graph of temperature change conductivity of the polymer electrolyte prepared in example 1 of the present invention.

Fig. 5 is a graph showing lithium ion mobility of the polymer electrolyte prepared in example 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Based on the ion conduction mechanism of polyester polymer electrolytes, reversible addition-fragmentation transfer polymerization and cyclic lactone ring-opening polymerization are combined, the polyester block copolymer is synthesized by a one-pot method, and the polyester-based solid polymer electrolytes (PESPEs) are prepared by blending the polyester block copolymer and lithium salt. The invention can adjust the chain structure of the block copolymer by changing the monomer types, the charge ratio, the temperature, the reaction time and other factors, and the obtained polymer has controllable molecular weight and narrower distribution. The block copolymer-based electrolyte has both excellent mechanical strength and electrochemical properties. The method for synthesizing the polyester block copolymer-based electrolyte by the one-pot method provides a new idea for synthesizing a solid polymer electrolyte material with excellent mechanical strength and electrochemical performance more conveniently and rapidly.

The invention designs and synthesizes the polyester block copolymer-based electrolyte. The electrolyte combines the advantages of mechanical strength and electrochemical performance of the two blocks, inhibits the semicrystallization of the polyester polymer and enhances the room-temperature ion conduction capability of the polyester polymer. The invention firstly applies the one-pot synthesis polyester block copolymer to the field of electrolyte, and compared with the traditional polyester electrolyte, the polyester block copolymer has a controllable structure, can flexibly adjust the type and length of two blocks, and combines the advantages of the two blocks to obtain the polymer electrolyte material meeting the practical application.

The structure of all polymers according to the invention is confirmed by nuclear magnetic resonance spectroscopy and the flow-out profile (GPC); the electrochemical performance and the thermodynamic performance of all the electrolyte membranes are respectively verified by an electrochemical impedance spectrum and an ion migration spectrogram.

The following are examples:

example 1

A polyester-based block copolymer-based polymer electrolyte having the chemical structure of the formula:

the preparation of the polyester block polymer-based electrolyte, as shown in fig. 1, comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 1.8g of styrene, 4.15g of epsilon-caprolactone and 3.4g of poly (ethylene glycol) methacrylate monomer are uniformly mixed to form a monomer mixture;

(2) adding 11.21mg of 4,4' -azobis (4-cyanovaleric acid) and 29.33mg of 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol to the monomer mixture and mixing them well;

(3) heating the raw material mixed solution to 50 ℃ in the argon atmosphere, reacting for 36 hours to enable the alkene monomer to generate reversible addition-fragmentation transfer polymerization, and subsequently heating to 110 ℃ to react for 48 hours to enable the cyclic lactone to generate ring-opening polymerization. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a block copolymer solution;

(4) adding the block copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain the polyester block copolymer 1 a;

a polyester block copolymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving the polyester block copolymer 1a in tetrahydrofuran to obtain a homogeneous solution, adding lithium perchlorate according to the mass ratio of the polymer to the lithium salt of 2:1, stirring to obtain a homogeneous solution, and casting the homogeneous solution to form a film to obtain the polymer electrolyte film with the thickness of 100 microns.

FIG. 2 shows the NMR spectrum of the polyester-based block polymer synthesized in this example. FIG. 3 is a gel chromatography outflow graph of the polyester-based block copolymer synthesized in this example, which shows that the number average molecular weight of the polymer is 76800, the molecular weight distribution is 1.17, and the synthesized molecular weight distribution is narrow.

Fig. 4 is a graph of the temperature-change conductivity of the polymer electrolyte prepared in this example. FIG. 5 is a graph showing the lithium ion mobility of the polymer electrolyte prepared in this example, from FIG. 4, it can be determined that the lithium ion conductivity of the electrolyte membrane was 1.1X 10 at room temperature^-5S cm^-1. Lithium ion measurement of electrolyte membrane by AC impedance method and DC polarization methodTransition number of molecules (t)_Li+). The cell was polarized at 10mV (. DELTA.V) and the initial state (I) was determined₀) And steady state (I)_S) And before polarization (R) is measured₀) And after polarization (R)_S) To obtain the interface resistance, as shown in FIG. 5, by calculating the formula t_Li+＝I_S(ΔV–I₀R₀)/I0(ΔV–I_SR_S) It was found that the transference number of lithium ions of the polymer electrolyte was 0.39.

Example 2

A polyester-based block copolymer-based polymer electrolyte having the chemical structure of the formula:

the preparation method of the polyester block polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 2.50g of styrene, 4.9g of delta-valerolactone and 2.8g of poly (ethylene glycol) methacrylate monomer are uniformly mixed to form a monomer mixture;

(2) adding 11.21mg of 4,4' -azobis (4-cyanovaleric acid) and 29.33mg of 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol to the monomer mixture and mixing them well;

(3) heating the raw material mixed solution to 60 ℃ in argon atmosphere for reaction for 30 hours to enable the alkene monomer to generate reversible addition-fragmentation transfer polymerization, and subsequently heating to 120 ℃ for reaction for 40 hours to enable the cyclic lactone to generate ring-opening polymerization reaction. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a block copolymer solution;

(4) adding the block copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain the polyester block copolymer 1 b;

a polyester block copolymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving the polyester block copolymer 1b in acetonitrile to obtain a homogeneous solution, adding lithium bis (trifluoromethyl) sulfonyl imide according to the mass ratio of the polymer to the lithium salt of 3:1, stirring to obtain the homogeneous solution, and casting the homogeneous solution to form a film to obtain the polymer electrolyte film with the thickness of 150 microns.

The number average molecular weight of the polymer was 71000, the molecular weight distribution was 1.19, and the molecular weight distribution of the synthesized polymer was narrow. The lithium ion conductivity of the electrolyte membrane was 1.2X 10 at room temperature^-5S cm^-1。

Example 3

A polyester-based block copolymer-based polymer electrolyte having the chemical structure of the formula:

the preparation method of the polyester block polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 2.14g of styrene, 10.6g of DL-lactide and 2.24g of poly (ethylene glycol) methacrylate monomer are uniformly mixed to form a monomer mixture;

(2) adding 11.21mg of 4,4' -azobis (4-cyanovaleric acid) and 29.33mg of 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol to the monomer mixture and mixing them well;

(3) heating the raw material mixed solution to 70 ℃ in argon atmosphere for reaction for 24 hours to enable the alkene monomer to generate reversible addition-fragmentation transfer polymerization, and subsequently heating to 130 ℃ for reaction for 32 hours to enable the cyclic lactone to generate ring-opening polymerization reaction. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a block copolymer solution;

(4) adding the block copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain a polyester block copolymer 1 c;

a polyester block copolymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving the polyester block copolymer 1c in N-methylpyrrolidone to obtain a homogeneous solution, adding lithium hexafluorophosphate according to the mass ratio of the polymer to the lithium salt of 4:1, stirring to obtain a homogeneous solution, and casting the homogeneous solution to form a film to obtain a polymer electrolyte film with the thickness of 100 microns.

The number average molecular weight of the polymer is 81000, the molecular weight distribution is 1.19, and the synthesized molecular weight distribution is narrow. The lithium ion conductivity of the electrolyte membrane was 9.6X 10 at room temperature^-6S cm^-1。

Example 4

A polyester-based block copolymer-based polymer electrolyte having the chemical structure of the formula:

the preparation method of the polyester block polymer-based electrolyte comprises the following steps:

(1) under anhydrous and oxygen-free conditions, 2.85g of styrene, 6.26g of trimethylene carbonate and 3.36g of poly (ethylene glycol) methacrylate monomer are uniformly mixed to form a monomer mixture;

(2) adding 11.21mg of 4,4' -azobis (4-cyanovaleric acid) and 29.33mg of 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol to the monomer mixture and mixing them well;

(3) heating the raw material mixed solution to 80 ℃ in argon atmosphere for reacting for 18 hours to enable the alkene monomer to generate reversible addition-fragmentation transfer polymerization, and subsequently heating to 140 ℃ for reacting for 24 hours to enable the cyclic lactone to generate ring-opening polymerization. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a block copolymer solution;

(4) adding the block copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain a polyester block copolymer 1 d;

a polyester block copolymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving the polyester block copolymer 1d in N, N-dimethylformamide to obtain a homogeneous solution, adding lithium perchlorate according to the mass ratio of the polymer to the lithium salt of 5:1, stirring to obtain a homogeneous solution, and casting the homogeneous solution to form a film to obtain a polymer electrolyte film with the thickness of 150 microns.

The number average molecular weight of the polymer was 89000, the molecular weight distribution was 1.18, and the molecular weight distribution synthesized was narrow. The lithium ion conductivity of the electrolyte membrane was 9.8X 10 at room temperature^-6S cm^-1。

Example 5

A polyester-based block copolymer-based polymer electrolyte having the chemical structure of the formula:

the preparation method of the polyester block polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 2.14g of styrene, 4.62g of epsilon-caprolactone and 2.24g of poly (ethylene glycol) methacrylate monomer are uniformly mixed to form a monomer mixture;

(2) adding 11.21mg of 4,4' -azobis (4-cyanovaleric acid) and 29.33mg of 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol to the monomer mixture and mixing them well;

(3) heating the raw material mixed solution to 90 ℃ in the argon atmosphere, reacting for 12 hours to enable the alkene monomer to generate reversible addition-fragmentation transfer polymerization, and subsequently heating to 150 ℃ to react for 16 hours to enable the cyclic lactone to generate ring-opening polymerization. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a block copolymer solution;

(4) adding the block copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain the polyester block copolymer 1 e;

a polyester block copolymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving the polyester block copolymer 1e in dimethyl sulfoxide to obtain a homogeneous solution, adding lithium perchlorate according to the mass ratio of the polymer to the lithium salt of 6:1, stirring to obtain the homogeneous solution, and casting the homogeneous solution to form a film to obtain the polymer electrolyte film with the thickness of 150 microns.

The number average molecular weight of the polymer is 62000, the molecular weight distribution is 1.19, and the synthesized molecular weight distribution is narrow. The lithium ion conductivity of the electrolyte membrane was 1.08X 10 at room temperature^-5S cm^-1。

Example 6

A polyester-based block copolymer-based polymer electrolyte having the chemical structure of the formula:

the preparation method of the polyester block polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 2.14g of styrene, 6.16g of epsilon-caprolactone and 1.68g of poly (ethylene glycol) methacrylate monomer are uniformly mixed to form a monomer mixture;

(2) adding 11.21mg of 4,4' -azobis (4-cyanovaleric acid) and 29.33mg of 2- (benzylsulfanylthiocarbonylsulfanyl) ethanol to the monomer mixture and mixing them well;

(3) heating the raw material mixed solution to 50 ℃ in the argon atmosphere, reacting for 36 hours to enable the alkene monomer to generate reversible addition-fragmentation transfer polymerization, and subsequently heating to 110 ℃ to react for 48 hours to enable the cyclic lactone to generate ring-opening polymerization. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a block copolymer solution;

(4) adding the block copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain the polyester block copolymer 1 f;

a polyester block copolymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving the polyester block copolymer 1f in acetonitrile to obtain a homogeneous solution, adding lithium hexafluorophosphate according to the mass ratio of the polymer to the lithium salt of 7:1, stirring to obtain the homogeneous solution, and casting the homogeneous solution to form a film to obtain the polymer electrolyte film with the thickness of 150 microns.

The number average molecular weight of the polymer is 66000, the molecular weight distribution is 1.18, and the synthesized molecular weight distribution is narrow. The lithium ion conductivity of the electrolyte membrane was 1.2X 10 at room temperature^-5S cm^-1。

The invention provides a method for synthesizing a polyester block copolymer-based electrolyte by a one-pot method, and provides a new idea for synthesizing a solid polymer electrolyte material with excellent mechanical strength and electrochemical performance. The invention combines a bifunctional chain transfer reagent and a bifunctional free radical initiator, and utilizes the characteristic that organic acid in 4,4' -azobis (4-cyanovaleric acid) can catalyze hydroxyl to initiate ring-opening reaction of cyclic lactone. Compared with the traditional ring-opening polymerization reaction, the organic metal catalyst has lower toxicity and structural stability, and overcomes the defect of metal residue of the traditional catalyst.

The invention combines reversible addition-fragmentation transfer (RAFT) polymerization and cyclic lactone ring-opening polymerization (ROP) reaction in one pot, so as to synthesize the polyester block copolymer more conveniently, quickly, greenly and efficiently. In some embodiments of the present invention, the chain structure of the block copolymer is adjusted by changing the monomer type and the charge ratio, the temperature, the reaction time, and other factors, and the obtained polymer has controllable molecular weight and narrow distribution. The one-pot method for synthesizing the polyester block copolymer-based electrolyte provided by the invention provides a new idea for synthesizing a solid polymer electrolyte material with excellent mechanical strength and electrochemical performance. The polymer electrolyte is applied to a lithium ion battery, a polymer electrolyte membrane with excellent electrochemical performance can be obtained, and the added lithium salt can be one or more of lithium salts commonly used in the lithium ion battery in the prior art.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.