Semi-interpenetrating network polymer solid electrolyte as well as preparation method and application thereof

Abstract

The invention discloses a semi-interpenetrating network polymer solid electrolyte as well as a preparation method and application thereof. Comprising the following components in parts by mass: 60-100 parts by weight of a polymer binder, 20-40 parts by weight of polyarylpiperidine and 10-150 parts by weight of a lithium salt, the structural formula of the polyarylpiperidine is shown in the specification, X <-> is halogen and / or bis (trifluoromethanesulfonic acid) imine (TFSI <->), and X <-> is halogen and / or bis (trifluoromethanesulfonic acid) imine (TFSI <->). And m and n are 0-100. The preparation method of the semi-interpenetrating network polymer solid electrolyte provided by the invention is simple, and the semi-interpenetrating network polymer solid electrolyte has relatively high specific capacity and excellent cycling stability and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a semi-interpenetrating network polymer solid electrolyte and a preparation method and application thereof. Background Art

[0002] Lithium batteries, with their high energy density and long cycle life, have become a core energy source for electric vehicles, portable electronic devices, and energy storage systems. However, traditional lithium batteries use liquid organic electrolytes, which pose safety risks such as volatility and flammability. While safety concerns can be partially mitigated by adding flame retardants, improving electrode materials, or improving diaphragm design, the risk of thermal runaway cannot be fundamentally eliminated. All-solid-state lithium batteries use solid electrolytes instead of liquid electrolytes, significantly improving safety and increasing energy density.

[0003] Solid-state electrolytes are the core component of all-solid-state lithium batteries, determining their ultimate performance. Currently, solid-state electrolytes are primarily categorized as inorganic and polymer electrolytes. While inorganic solid electrolytes (such as oxides and sulfides) offer high ionic conductivity, their rigid structure makes processing difficult, interfacial impedance high, and lithium dendrites easily grow along grain boundaries, causing short circuits. In contrast, polymer electrolytes offer advantages such as flexibility and close interfacial contact, but they generally have low ionic conductivity (typically less than 0.1 mS / cm at room temperature), insufficient mechanical strength, and are susceptible to thermal degradation at high temperatures, resulting in reduced cycling stability and limiting their practical application. While existing polymer electrolytes, such as polyethylene oxide (PEO), can enhance ion mobility by combining with lithium salts, their high crystallinity limits their room-temperature conductivity. While the introduction of inorganic fillers or copolymers can improve performance, this often sacrifices processability or mechanical strength. Furthermore, existing preparation processes are complex, making large-scale production difficult. Therefore, developing a polymer solid electrolyte with high ionic conductivity, excellent mechanical properties and high-temperature stability, and simplifying its preparation process, has become the key to promoting the commercial application of all-solid-state lithium batteries. Summary of the Invention

[0004] To address the above technical problems, the present invention provides a semi-interpenetrating network polymer solid electrolyte, its preparation method, and application. By constructing a semi-interpenetrating network, the present invention enhances its mechanical strength. The cationic groups of the cross-linked polyarylpiperidine can inhibit the migration of anionic groups through electrostatic interaction, thereby increasing the lithium ion migration rate and improving the battery's charge-discharge efficiency and stability. Application of the polymer solid electrolyte in lithium-ion batteries demonstrates excellent cycling performance. The preparation method provided by the present invention is simple and suitable for large-scale production.

[0005] The first object of the present invention is to provide a semi-interpenetrating network polymer solid electrolyte, comprising the following components, in parts by weight: 60 to 100 parts by weight of a polymer binder, 20 to 40 parts by weight of a polyarylpiperidine, and 10 to 150 parts by weight of a lithium salt: The structural formula of the polyarylpiperidine is: , X - is halogen and / or bis(trifluoromethanesulfonic acid)imide (TFSI - ); The structural formula of the polyarylpiperidine reaction monomer is: .

[0006] M is a halogen; m and n are 0-100, and m and n are the degree of polymerization.

[0007] In some embodiments of the present invention, the halogen includes chlorine and / or bromine.

[0008] In some embodiments of the present invention, the polymer binder includes one or more of polyethylene oxide, polyethylene glycol, polyvinyl alcohol or derivatives thereof.

[0009] In some embodiments of the present invention, the polymer binder has a number average molecular weight of 5,000 to 2,000,000 Daltons.

[0010] In some embodiments of the present invention, the lithium salt includes one or more of lithium bis(trifluoromethanesulfonate)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, and derivatives thereof.

[0011] In some embodiments of the present invention, the polyarylpiperidine reaction monomer is prepared by the following method: , In a reaction organic solvent, biphenyl and N-methyl-4-piperidone are subjected to acid-catalyzed polymerization under the action of a catalyst to obtain a first polymer; Wherein, M is a halogen, m and n are the degree of polymerization, and the value of m or n can be set by adjusting the raw material ratio.

[0012] The obtained first polymer and CH3CH2Y, The reaction is carried out in an organic solvent to obtain a polyarylpiperidine reaction monomer, wherein Y is a halogen, specifically Cl or Br.

[0013] In some embodiments of the present invention, the reaction organic solvent includes one or more of dimethyl sulfoxide, N,N-dimethylformamide and N-methylpyrrolidone; The mass ratio of biphenyl to N-methyl-4-piperidone is 1:(0.5-1.0); The catalyst is selected from trifluoromethanesulfonic acid; The first polymer and CH3CH2Y, The mass ratio is 1: (0.1 ~ 0.5): (0.1 ~ 0.5).

[0014] The second object of the present invention is to provide a method for preparing the semi-interpenetrating network polymer solid electrolyte, comprising the following steps: The polymer binder, polyarylpiperidine and lithium salt are mixed in a solvent and stirred at 20° C. to 100° C. to obtain an electrolyte solution; The obtained electrolyte solution is coated on the surface of a substrate, heated and dried to cause a cross-linking reaction of the polyarylpiperidine; then dried in an inert gas atmosphere, and peeled off from the polytetrafluoroethylene plate to obtain the semi-interpenetrating network polymer solid electrolyte.

[0015] In some embodiments of the present invention, the mass ratio of solute to solvent in the electrolyte solution is 1:(5-20); the drying conditions are: drying temperature of 60°C to 120°C, and drying time of 6 hours to 48 hours; the drying time in an inert gas atmosphere is 5 to 7 days, and the drying temperature is 25°C; the inert gas of the inert atmosphere includes nitrogen and / or argon; and the substrate includes a polytetrafluoroethylene plate.

[0016] The third object of the present invention is to provide a lithium-ion battery comprising the semi-interpenetrating network polymer solid electrolyte.

[0017] The technical solution of the present invention has the following advantages over existing technologies: the cationic groups of the cross-linked polyarylpiperidine in the present invention can inhibit the migration of anionic groups through electrostatic interaction, thereby increasing the lithium ion transference number and improving the battery's charge and discharge efficiency and stability. The semi-interpenetrating network formed by the cross-linked polyarylpiperidine and the polymer binder can enhance the mechanical strength of the polymer electrolyte and improve battery stability.

[0018] The semi-IPN polymer solid electrolyte provided by the present invention has a simple preparation method and is suitable for large-scale production. The semi-IPN in the present invention refers to a polymer membrane in which one of the two polymers is cross-linked and the other is non-cross-linked. In the present invention, the polyarylpiperidine is cross-linked, and the polymer binder is non-cross-linked. The semi-IPN polymer solid electrolyte of the present invention has a high ionic conductivity (0.75 mS / cm at 80°C). When the semi-IPN polymer solid electrolyte of the present invention is assembled into a lithium iron phosphate / lithium metal button cell, the discharge capacity at 0.1C is 165 mAh g -1, after 300 cycles at a rate of 0.1C, the capacity retention rate is 90.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 This is a picture of the solid electrolyte obtained in Example 1 of the present invention; Figure 2 is a hydrogen nuclear magnetic resonance spectrum of the polyarylpiperidine obtained in Example 1 of the present invention; Figure 3 1 is a Fourier transform infrared spectrum of the polyarylpiperidine obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0021] The reagents and instruments used in the present invention without manufacturer indication are all conventional products that can be purchased from the market.

[0022] Example 1 This embodiment provides a method for preparing a semi-interpenetrating network polymer solid electrolyte, which is specifically as follows: 1. Preparation of polyarylpiperidine reaction monomer: 1. The structural formula of polyarylpiperidine is as follows: , X - TFSI - , n is 100, and m is 50.

[0023] The structural formula of the polyarylpiperidine reaction monomer is: .

[0024] 2. The polyarylpiperidine reaction monomer is prepared by the following method: (1) 1.54 g of biphenyl and 1.13 g of N-methyl-4-piperidone were dissolved in 20 ml of dichloromethane, and 8.8 ml of trifluoromethanesulfonic acid was added. The mixture was subjected to acid-catalyzed polymerization at room temperature. After the reaction was allowed to proceed for 24 hours, the reaction product was precipitated, filtered, washed, and dried to obtain a first polymer. (2) 1.24 g of the first polymer, 0.273 g of bromoethane, and 0.382 g of 4-chloromethylstyrene were dissolved in 15 ml of dimethyl sulfoxide and reacted at 60 ° C for 24 hours. The reaction product was precipitated, filtered, washed, and dried to obtain a polyarylpiperidine reaction monomer. The obtained polyarylpiperidine reaction monomer was characterized and its H NMR spectrum was shown in FIG. Figure 2 .

[0025] 2. The preparation steps of the semi-interpenetrating network polymer solid electrolyte are as follows: add 0.8g polyethylene oxide (number average molecular weight of 2000000 Dalton), 0.12g polyarylpiperidine and 0.7g lithium bis(trifluoromethylsulfonate)imide to 30g N,N-dimethylformamide, stir evenly at 25°C to obtain an electrolyte solution; apply the electrolyte solution on a polytetrafluoroethylene plate, place it at 60°C to dry for 12h, and then place it at 120°C to keep warm for 4h to crosslink the polyarylpiperidine. Place the polytetrafluoroethylene plate in an argon environment and dry for 7 days, peel the electrolyte membrane from the polytetrafluoroethylene plate to obtain a semi-interpenetrating network polymer solid electrolyte. The obtained semi-interpenetrating network polymer solid electrolyte was characterized, and its Fourier transform infrared spectrum is shown in Figure 3 , and its ionic conductivity at 80°C was measured to be 0.75 mS / cm.

[0026] 3. Application: A button cell was assembled using metallic lithium as the negative electrode, lithium iron phosphate as the positive electrode, and the semi-interpenetrating polymer solid electrolyte prepared above as the electrolyte layer. Charge and discharge tests were conducted using a Blue Power battery test system. At 60°C, the discharge capacity at 0.1C was 165 mAh·g. -1 , after 300 cycles at a rate of 0.1C, the capacity retention rate is 90.5%.

[0027] Example 2 The preparation method of the semi-interpenetrating network polymer solid electrolyte provided in this embodiment is specifically as follows: 1. Preparation of polyarylpiperidine: 1. The structural formula of polyarylpiperidine is as follows: , The structural formula of the polyarylpiperidine reaction monomer is: , X - TFSI - , n is 100, and m is 70.

[0028] 2. The preparation method of polyarylpiperidine reaction monomer is as follows: The polyarylpiperidine reaction monomer is prepared by the following method: , (1) 1.54 g of biphenyl and 1.13 g of N-methyl-4-piperidone were dissolved in 20 ml of dichloromethane, and 8.8 ml of trifluoromethanesulfonic acid was added. The mixture was subjected to acid-catalyzed polymerization at room temperature. After the reaction was allowed to proceed for 24 hours, the reaction product was precipitated, filtered, washed, and dried to obtain the first-stage polymer. (2) 1.24 g of the first step polymer, 0.164 g of bromoethane, and 0.534 g of 4-chloromethylstyrene were dissolved in 15 ml of dimethyl sulfoxide and reacted at 60°C for 24 hours. The reaction product was precipitated, filtered, washed, and dried to obtain a polyarylpiperidine reaction monomer.

[0029] The preparation steps for the semi-interpenetrating polymer solid electrolyte are as follows: 0.8g of polyethylene oxide (number-average molecular weight 2,000,000 Daltons), 0.13g of poly(arylpiperidine), and 0.7g of lithium bis(trifluoromethylsulfonate)imide were added to 30g of N,N-dimethylformamide and stirred at 25°C to obtain an electrolyte solution. The electrolyte solution was coated onto a polytetrafluoroethylene (PTFE) plate, dried at 60°C for 12 hours, and then kept at 120°C for 4 hours to crosslink the poly(arylpiperidine). The PTFE plate was dried in an argon atmosphere for 7 days. The electrolyte membrane was then peeled from the PTFE plate to obtain the semi-interpenetrating polymer solid electrolyte. The ionic conductivity of the electrolyte was measured to be 0.71mS / cm at 80°C.

[0030] 3. Application: A button cell was assembled with lithium metal as the negative electrode, lithium iron phosphate as the positive electrode, and the semi-interpenetrating polymer solid electrolyte prepared above as the electrolyte layer. The charge and discharge test was carried out using a blue battery test system. At 60°C, the discharge capacity at 0.1C was 162 mAh g -1 , after 300 cycles at a rate of 0.1C, the capacity retention rate is 89.5%.

[0031] Comparative Example 1 The preparation steps for the polyethylene oxide-based polymer solid electrolyte are as follows: 0.8 g polyethylene oxide (number average molecular weight 2,000,000 Daltons) and 0.7 g lithium bis(trifluoromethylsulfonate)imide were added to 30 g N,N-dimethylformamide and stirred at 25°C to obtain an electrolyte solution. The electrolyte solution was then coated onto a polytetrafluoroethylene plate and dried at 60°C for 12 hours. The plate was then dried in an argon atmosphere for 10 days. The electrolyte membrane was then peeled off from the plate to obtain the polyethylene oxide-based polymer solid electrolyte.

[0032] 2. Application: Using metallic lithium as the negative electrode, lithium iron phosphate as the positive electrode, and the polyethylene oxide-based polymer solid electrolyte prepared above as the electrolyte layer, a button cell was assembled and the charge and discharge test was conducted using a blue battery test system. At 60°C, the discharge capacity at 0.1C was 148 mAh g -1 , after 300 cycles at a rate of 0.1C, the capacity retention rate is 69.4%.

[0033] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A semi-interpenetrating polymer solid electrolyte, characterized in that: The invention comprises the following components, calculated by weight: 60 to 100 parts by weight of a polymer binder, 20 to 40 parts by weight of a polyarylpiperidine reaction monomer, and 10 to 150 parts by weight of a lithium salt: The structural formula of the polyarylpiperidine is: , X - is halogen and / or bis(trifluoromethanesulfonic acid)imide; The structural formula of the polyarylpiperidine reaction monomer is: M is a halogen; m and n are 0-100.

2. The semi-interpenetrating polymer solid electrolyte according to claim 1, characterized in that The halogen includes chlorine and / or bromine.

3. The semi-interpenetrating polymer solid electrolyte according to claim 1, characterized in that The polymer binder includes one or more of polyethylene oxide, polyethylene glycol, polyvinyl alcohol or derivatives thereof.

4. The semi-interpenetrating polymer solid electrolyte according to claim 1, characterized in that The number average molecular weight of the polymer binder is 5,000 to 2,000,000 Daltons.

5. The semi-interpenetrating polymer solid electrolyte according to claim 1, characterized in that The lithium salt includes one or more of lithium bis(trifluoromethanesulfonate)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate and derivatives thereof.

6. The semi-interpenetrating polymer solid electrolyte according to claim 1, characterized in that The polyarylpiperidine reaction monomer is prepared by the following method: In a reaction organic solvent, biphenyl and N-methyl-4-piperidone are subjected to acid-catalyzed polymerization under the action of a catalyst to obtain a first polymer; The obtained first polymer and CH3CH2Y, The reaction is carried out in an organic solvent to obtain a polyarylpiperidine, wherein Y is a halogen.

7. The semi-interpenetrating polymer solid electrolyte according to claim 6, characterized in that The reaction organic solvent includes one or more of dimethyl sulfoxide, N,N-dimethylformamide and N-methylpyrrolidone; The mass ratio of biphenyl to N-methyl-4-piperidone is 1:(0.5-1.0); The catalyst is selected from trifluoromethanesulfonic acid; The first polymer and CH3CH2Y, The mass ratio is 1: (0.1 ~ 0.5): (0.1 ~ 0.5).

8. The method for preparing a semi-interpenetrating polymer solid electrolyte according to any one of claims 1 to 7, characterized in that: The following steps are involved: The polymer binder, polyarylpiperidine and lithium salt are mixed in a solvent and stirred at 20° C. to 100° C. to obtain an electrolyte solution; The obtained electrolyte solution is coated on the surface of a substrate, heated and dried to cause a cross-linking reaction of the polyarylpiperidine; then placed in an inert gas atmosphere for drying, and peeled off from the substrate to obtain the semi-interpenetrating network polymer solid electrolyte.

9. The preparation method according to claim 8, characterized in that The mass ratio of solute to solvent in the electrolyte solution is 1:(5-20); the drying conditions are as follows: the drying temperature is 60°C to 120°C, the drying time is 6 hours to 48 hours; the drying time in an inert gas atmosphere is 5 to 7 days, and the drying temperature is 10°C to 40°C; The inert atmosphere includes nitrogen and / or argon. The substrate includes a polytetrafluoroethylene sheet.

10. A lithium ion battery, characterized in that: The method comprises the semi-interpenetrating polymer solid electrolyte according to any one of claims 1 to 7.

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