Bio-based solid polymer electrolyte, preparation method and application thereof, and gel polymer electrolyte of bio-based solid polymer electrolyte

Abstract

The invention relates to the technical field of battery electrolytes, in particular to a bio-based solid polymer electrolyte, a preparation method and application thereof and a gel polymer electrolyte.The preparation method comprises the following steps that a polymer monomer 1, a polymer monomer 2, an initiator, a lithium salt and an additive are mixed and stirred to be uniform, and a precursor solution is obtained; and adding a cross-linking agent into the precursor solution, and heating and curing to obtain the solid polymer electrolyte. The electrolyte membrane prepared by the invention is compact and uniform, has a large electrochemical window, and has certain mechanical properties. The requirements of solid-state lithium ion battery polymer electrolyte are met, and the stability and the safety are relatively good. The electrolyte prepared by the invention has the advantages of simple design, easiness in manufacturing, safety in use, low raw material price and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrolytes, and particularly relates to a bio-based solid polymer electrolyte, a preparation method and application thereof, and a gel polymer electrolyte thereof. Background Art

[0002] Lithium-ion batteries have been widely used in many key fields such as electric vehicles, energy storage systems, and electronic products due to their many advantages such as high rated voltage, high energy density, long cycle life, and low self-discharge. However, in recent years, frequent safety accidents of lithium-ion batteries, such as fires and explosions, not only pose a serious threat to people's lives and property safety but also arouse deep concern from all sectors of society about the safety issues of lithium-ion batteries. These safety problems mainly stem from the complex chemical components inside the battery, such as flammable electrolytes, and the abuse of external conditions, such as overcharging, short-circuiting, and high temperature. During the thermal runaway process of the battery, the flammable, toxic, and easily leaked electrolyte participates in most of the reactions in the thermal runaway process of the lithium-ion battery.

[0003] In order to fundamentally solve the safety hazards of lithium-ion batteries, researchers are actively exploring new battery technology paths. Among them, solid-state batteries are regarded as an ideal solution to the safety problems of lithium-ion batteries due to their significant advantages in energy density, production efficiency, and safety compared with liquid batteries. The core of a solid-state battery is to replace the traditional liquid electrolyte with a solid electrolyte with outstanding characteristics such as high thermal stability, non-leakage, and non-flammability. This can not only effectively isolate the direct contact between the internal components of the battery and the external environment, reducing the risk of thermal runaway, but also further improve the energy density and cycle stability of the battery.

[0004] Among many solid electrolyte materials, solid polymer electrolytes (SPEs) have the best interfacial wetting performance and film-forming performance, and they have excellent processing performance and low density characteristics that other solid electrolytes do not have, meeting the current design requirements for battery lightening and flexible wearability.

[0005] However, the electrochemical window of polymer solid electrolytes is relatively narrow and is easily oxidized by high-voltage positive electrodes. Especially when paired with high-voltage positive electrode materials such as lithium cobaltate and lithium nickel cobalt manganate, violent electrochemical oxidative decomposition will occur, resulting in a sharp decline in battery performance. At the same time, most of the raw materials used in current polymer electrolytes, such as polyacrylonitrile and polymethyl methacrylate, rely on fossil fuels such as petroleum. With the development of clean energy, more environmentally friendly raw materials are needed to replace petroleum-based raw materials. Summary of the Invention

[0006] To address the deficiencies of the existing technology, the present invention provides a bio-based solid polymer electrolyte, its preparation method and application, and its gel polymer electrolyte. The polymer electrolyte prepared by crosslinking bio-based monomers not only has a large electrochemical window and can maintain stable cycling performance in high-voltage cathode batteries such as lithium nickel cobalt manganese oxide, but also exhibits good toughness and mechanical properties, effectively improving the safety and reliability of the battery. More importantly, the bio-based monomer raw materials used are renewable and widely sourced, which not only helps reduce dependence on fossil fuels such as petroleum, but also promotes resource recycling, reduces environmental pollution, and is more in line with the current green and sustainable development goals.

[0007] To achieve the above object, the technical solution of the present invention is: A preparation method of a bio-based solid polymer electrolyte, comprising the following steps:

[0008] (1) Mix polymer monomer 1, polymer monomer 2, initiator, lithium salt, and additive, and stir evenly to obtain a precursor solution;

[0009] (2) Add a crosslinking agent to the precursor solution and heat-cure to obtain a solid polymer electrolyte;

[0010] The structural general formula of the polymer monomer 1 is formula (Ⅰ), the structural general formula of the polymer monomer 2 is formula (Ⅱ), and the structural general formula of the crosslinking agent is formula (Ⅲ). The structural formulas of formula (Ⅰ), formula (Ⅱ), and formula (Ⅲ) are as follows:

[0011]

[0012]

[0013] Wherein, R1, R2, R3, and R4 each independently selected from substituted or unsubstituted alkyl groups. When substituted, the substituent is selected from halogen; the number of carbon atoms in the alkyl group is less than or equal to 20, the value range of n in formula (Ⅰ) is 17-20, and the value range of m in formula (Ⅲ) is 11-14.

[0014] Further, the molar ratio of the polymer monomer 1, polymer monomer 2, initiator, and crosslinking agent is 100:233-400:3-5:3-10, the mass of the lithium salt accounts for 0.1-50 wt% of the total mass of the solid polymer electrolyte, and the additive accounts for 0-80 wt% of the total mass of the solid polymer electrolyte.

[0015] Further, the initiator is compound 1;

[0016]

[0017] Further, in the step (2), the curing heating temperature is 40 to 90 °C, and the heating time is 24 to 96 h.

[0018] Further, a plasticizer is added in the step (2), and the plasticizer accounts for 0 to 10 wt% of the sum of the masses of the reactants. The plasticizer is selected from any one of Compound 2 to Compound 3;

[0019]

[0020] Further, the lithium salt is selected from one or more of lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoroxalate phosphate, lithium oxalate phosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium bis(difluoromethanesulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide.

[0021] Further, the additive is selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene copolymer, polyacrylic acid, polyacrylonitrile, polymethyl methacrylate carbonate, polyethylene oxide, polyethylene, polypropylene, polyamide, polyimide, polyvinyl alcohol, polyvinyl butyral, polysiloxane, polytetrafluoroethylene, inorganic filler oxide solid electrolyte, sulfide solid electrolyte, silicon suboxide, silicon dioxide, titanium oxide, zirconium oxide, aluminum oxide, boehmite, montmorillonite, tetraethylene glycol dimethyl ether, and plastic crystal.

[0022] A solid polymer electrolyte prepared by the preparation method of the above-mentioned bio-based solid polymer electrolyte.

[0023] An application of the above-mentioned solid polymer electrolyte in a lithium battery, the lithium battery includes a positive electrode, a negative electrode, and a separator, and further includes the above-mentioned solid polymer electrolyte disposed between the positive electrode and the negative electrode.

[0024] A bio-based gel polymer electrolyte, including the above-mentioned solid polymer electrolyte and a lithium-ion battery electrolyte solution; the lithium-ion battery electrolyte solution includes a lithium salt, a non-aqueous organic solvent, and an additive;

[0025] The lithium salt is at least one of lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoroxalate phosphate, lithium oxalate phosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium bis(difluoromethanesulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide, and the lithium salt content accounts for 0.1 to 25.0 wt% of the total mass of the lithium-ion battery electrolyte solution;

[0026] The non-aqueous organic solvent is at least one of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate, γ-butyrolactone, ethylene glycol dimethyl ether, tetrahydrofuran, tetrahydropyran, dioxolane, dimethyl sulfoxide, dimethyl sulfone, acetone, and N,N-dimethylformamide, and the content of the non-aqueous organic solvent accounts for 20.0-70.0 wt% of the total mass of the lithium-ion battery electrolyte;

[0027] The additive is at least one of fluoroethylene carbonate, vinylene carbonate, 1,3-propane sultone, ethylene sulfate, methylene methanedisulfonate, propylene sultone, citraconic anhydride, succinonitrile, adiponitrile, ethylene glycol diether, and hexane trinitrile, and the content of the additive accounts for 0.1-20.0 wt% of the total mass of the lithium-ion battery electrolyte.

[0028] The beneficial effects achieved by the present invention are as follows:

[0029] The solid polymer electrolyte prepared by the present invention has low raw material prices, a simple preparation method, and renewable bio-based raw materials that are more environmentally friendly; the unique cross-linked structure increases the mechanical strength, endows it with certain mechanical properties, enables it to withstand greater stress and challenges, and extends the service life of the electrolyte; the introduction of polyester increases the oxidation stability, shows high stability to high-voltage positive electrodes, and also improves the lithium-ion transference number of the electrolyte to a certain extent, which has a positive effect on improving the charge and discharge rate and cycle efficiency of the battery; the battery assembled with the solid polymer electrolyte prepared by the present invention exhibits excellent cycle stability and rate performance, and can maintain efficient and stable energy output whether in long-term use or fast charge and discharge scenarios, providing a more reliable choice for fields such as electric vehicles and energy storage systems.

[0030] The present invention can realize the regulation of the matrix structure of the solid polymer electrolyte to change its properties and be applied to various different situations; the gel electrolyte formed by combining the solid polymer electrolyte and the electrolyte in the present invention also has excellent properties.

[0031] The present invention introduces bio-based substances into the polymer main chain, which is structurally stable in the battery and can replace conventional petroleum-based raw materials such as PAN and PMMA, promoting the transformation of clean energy. Description of the Drawings

[0032] Figure 1 is a schematic diagram of the mechanism of the solid electrolyte of the present invention;

[0033] Figure 2 is a solid polymer electrolyte membrane prepared by casting;

[0034] Figure 3 is the infrared spectrum of the solid polymer electrolyte prepared in Example 1;

[0035] Figure 4 is the graph of the ionic conductivity - temperature relationship of the solid polymer electrolyte;

[0036] Figure 5 is the linear sweep voltammetry curve of the steel sheet / solid electrolyte / lithium sheet battery of Example 1;

[0037] Figure 6 is the graph of the lithium ion transference number of the lithium / solid electrolyte / lithium battery of Example 1:

[0038] Figure 7 is the 0.1C cycling graph of the lithium iron phosphate / solid electrolyte / lithium sheet battery of Example 1 at 60 °C:

[0039] Figure 8 is the 0.1C cycling graph of the lithium nickel cobalt manganese oxide / solid electrolyte / lithium battery of Example 1 at 60 °C:

[0040] Figure 9 is the rate graph of the lithium iron phosphate / gel electrolyte / lithium battery of Example 8 at 60 °C:

[0041] Figure 10 is the 0.1C cycling graph of the lithium iron manganese phosphate / gel electrolyte / lithium battery of Example 8 at 25 °C. Detailed implementation mode

[0042] In order to better understand the purpose, structure and function of the present invention, the following further describes in detail a bio-based solid polymer electrolyte, its preparation method and application, and its gel polymer electrolyte of the present invention with reference to the accompanying drawings.

[0043] The following examples are only used to illustrate the present invention, but the present invention is not limited to these examples. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention. All kinds of raw materials involved in the specification are purchased from the market, and the sources, purities and model numbers of some reagents are shown in Table 1 and Table 2.

[0044] Table 1 Reagent sources and purities

[0045]

[0046]

[0047] Table 1 Instruments and equipment

[0048]

[0049] Method for fabricating a positive electrode sheet: Superconductive carbon black (100 mg) and a positive electrode active material (800 mg) are mixed and ground for 20 minutes to form a powder. Then, a solution of polyvinylidene fluoride in N-methylpyrrolidone with a concentration of 2.5 wt% (4000 mg) is added to the above mixed powder, and a heating magnetic stirrer is used at 200 revolutions per minute for 12 hours to obtain a positive electrode paste. The above paste is scraped onto an aluminum foil with a thickness of 16 microns using a 200-micron doctor blade, transferred to a forced-air drying oven and dried at 60°C for 10 hours, and then transferred to a vacuum drying oven and vacuum-dried at 120°C for 10 hours; after pressing with a press, it is cut into circular pieces with a diameter of 14 mm for use. The positive electrode active material is lithium iron phosphate, lithium iron manganese phosphate, or nickel cobalt manganese lithium 622 (NCM622).

[0050] The structures of polymer monomer 1, polymer monomer 2, crosslinking agent, initiator, and plasticizer used in the following examples are as follows: where n in polymer monomer 1 is 17 - 20, and m in the crosslinking agent is 11 - 14.

[0051]

[0052] Example 1

[0053] In an argon glove box (moisture <0.01 ppm, oxygen <0.01 ppm), polymer monomer 1 (0.4 g, 0.421 mmol) and polymer monomer 2 (266.4 mg, 1.684 mmol) are weighed and added to a sample bottle, then an initiator (3.45 mg, 0.021 mmol) and lithium bis(trifluoromethanesulfonyl)imide (133.3 mg) are added, and a magnetic stir bar is added and stirred for 4 hours to obtain a precursor. Then, a crosslinking agent (15.7 mg, 0.021 mmol) is added dropwise, and a plasticizer b (19.9 mg) is added, and stirred to obtain a liquid electrolyte, which is heated and cured to obtain a solid polymer electrolyte.

[0054] Battery assembly: Assemble a CR 2032 type button cell in the order of "negative electrode case - lithium sheet - electrolyte membrane - positive electrode sheet - spacer - spring sheet - positive electrode case". According to the test content, the electrode sheets are selected from steel sheets, lithium iron phosphate positive electrode sheets, NCM622 positive electrode sheets, lithium iron manganese phosphate positive electrode sheets, and lithium sheets.

[0055] Example 2

[0056] In an argon glove box (with moisture < 0.01 ppm and oxygen < 0.01 ppm), weigh and add polymer monomer 1 (0.4 g, 0.421 mmol) and polymer monomer 2 (266.4 mg, 1.684 mmol) into a sample bottle. Then add initiator (3.45 mg, 0.021 mmol) and lithium bis(trifluoromethanesulfonyl)imide (133.3 mg). Add a magnetic stir bar and stir for 4 hours to obtain a precursor. Then dropwise add a crosslinking agent (15.7 mg, 0.021 mmol) and stir to obtain a liquid electrolyte. After heating and curing, a solid polymer electrolyte is obtained.

[0057] Battery assembly: Assemble a CR 2032 type coin cell in the order of "negative electrode case - lithium sheet - electrolyte membrane - positive electrode sheet - gasket - spring piece - positive electrode case". According to the test content, the electrode sheets are respectively selected from steel sheets, lithium iron phosphate positive electrode sheets, NCM622 positive electrode sheets, lithium manganese iron phosphate positive electrode sheets, and lithium sheets.

[0058] Example 3

[0059] In an argon glove box (with moisture < 0.01 ppm and oxygen < 0.01 ppm), weigh and add polymer monomer 1 (0.4 g, 0.421 mmol) and polymer monomer 2 (266.4 mg, 1.684 mmol) into a sample bottle. Then add initiator (3.45 mg, 0.021 mmol) and lithium bis(trifluoromethanesulfonyl)imide (199.9 mg). Add a magnetic stir bar and stir for 4 hours to obtain a precursor. Then dropwise add a crosslinking agent (22.1 mg, 0.029 mmol) and plasticizer b (21.6 mg) and stir to obtain a liquid electrolyte. After heating and curing, a solid polymer electrolyte is obtained.

[0060] Battery assembly: Assemble a CR 2032 type coin cell in the order of "negative electrode case - lithium sheet - electrolyte membrane - positive electrode sheet - gasket - spring piece - positive electrode case". According to the test content, the electrode sheets are respectively selected from steel sheets, lithium iron phosphate positive electrode sheets, NCM622 positive electrode sheets, lithium manganese iron phosphate positive electrode sheets, and lithium sheets.

[0061] Example 4

[0062] In an argon glove box (with moisture < 0.01 ppm and oxygen < 0.01 ppm), weigh and add polymer monomer 1 (0.4 g, 0.421 mmol) and polymer monomer 2 (155.4 mg, 0.982 mmol) into a sample bottle. Then add initiator (2.31 mg, 0.014 mmol) and lithium bis(trifluoromethanesulfonyl)imide (111 mg). Add a magnetic stir bar and stir for 4 hours to obtain a precursor. Then dropwise add a crosslinking agent (15.7 mg, 0.021 mmol) and stir to obtain a liquid electrolyte. After heating and curing, a solid polymer electrolyte is obtained.

[0063] Battery assembly: Assemble a CR 2032 type button cell in the order of "negative electrode case - lithium sheet - electrolyte membrane - positive electrode sheet - gasket - shrapnel - positive electrode case". According to the test content, the electrode sheets are respectively selected from steel sheets, lithium iron phosphate positive electrode sheets, NCM622 positive electrode sheets, lithium manganese iron phosphate positive electrode sheets, and lithium sheets.

[0064] Example 5

[0065] In an argon glove box (moisture < 0.01 ppm, oxygen < 0.01 ppm), weigh and add polymer monomer 1 (0.4 g, 0.421 mmol) and polymer monomer 2 (155.4 mg, 0.982 mmol) to a sample bottle, then add an initiator (2.31 mg, 0.014 mmol) and lithium bis(trifluoromethanesulfonyl)imide (111 mg), add a magnetic stir bar and stir for 4 hours to obtain a precursor, then dropwise add a crosslinking agent (15.7 mg, 0.021 mmol), add plasticizer b (16.6 mg) and stir to obtain a liquid electrolyte, and obtain a solid polymer electrolyte after heating and curing.

[0066] Battery assembly: Assemble a CR 2032 type button cell in the order of "negative electrode case - lithium sheet - electrolyte membrane - positive electrode sheet - gasket - shrapnel - positive electrode case". According to the test content, the electrode sheets are respectively selected from steel sheets, lithium iron phosphate positive electrode sheets, NCM622 positive electrode sheets, lithium manganese iron phosphate positive electrode sheets, and lithium sheets.

[0067] Example 6

[0068] In an argon glove box (moisture < 0.01 ppm, oxygen < 0.01 ppm), weigh and add polymer monomer 1 (0.4 g, 0.421 mmol) and polymer monomer 2 (155.4 mg, 0.982 mmol) to a sample bottle, then add an initiator (2.31 mg, 0.014 mmol) and lithium bis(trifluoromethanesulfonyl)imide (167 mg), add a magnetic stir bar and stir for 4 hours to obtain a precursor, then dropwise add a crosslinking agent (15.7 mg, 0.021 mmol), add plasticizer b (18.1 mg) and stir to obtain a liquid electrolyte, and obtain a solid polymer electrolyte after heating and curing.

[0069] Battery assembly: Assemble a CR 2032 type button cell in the order of "negative electrode case - lithium sheet - electrolyte membrane - positive electrode sheet - gasket - shrapnel - positive electrode case". According to the test content, the electrode sheets are respectively selected from steel sheets, lithium iron phosphate positive electrode sheets, NCM622 positive electrode sheets, lithium manganese iron phosphate positive electrode sheets, and lithium sheets.

[0070] Example 7

[0071] In an argon glove box (moisture < 0.01 ppm, oxygen < 0.01 ppm), weigh and add polymer monomer 1 (0.4 g, 0.421 mmol) and polymer monomer 2 (155.4 mg, 0.982 mmol) into a sample bottle, then add an initiator (2.31 mg, 0.014 mmol) and lithium bis(trifluoromethanesulfonyl)imide (167 mg). Add a magnetic stir bar and stir for 4 hours to obtain a precursor. Then, dropwise add a crosslinking agent (22.1 mg, 0.029 mmol) and plasticizer b (18.1 mg), and stir to obtain a liquid electrolyte. After heating and curing, a solid polymer electrolyte is obtained.

[0072] Battery assembly: Assemble a CR 2032 coin cell in the order of "negative electrode case - lithium sheet - electrolyte membrane - positive electrode sheet - gasket - shrapnel - positive electrode case". According to the test content, the electrode sheets are selected from steel sheets, lithium iron phosphate positive electrode sheets, NCM622 positive electrode sheets, lithium manganese iron phosphate positive electrode sheets, and lithium sheets.

[0073] Example 8

[0074] In an argon glove box (moisture < 0.01 ppm, oxygen < 0.01 ppm), weigh and add polymer monomer 1 (0.4 g, 0.421 mmol) and polymer monomer 2 (266.4 mg, 1.684 mmol) into a sample bottle, then add an initiator (3.45 mg, 0.021 mmol) and lithium bis(trifluoromethanesulfonyl)imide (133.3 mg). Add a magnetic stir bar and stir for 4 hours to obtain a precursor. Then, dropwise add a crosslinking agent (15.7 mg, 0.021 mmol) and plasticizer b (19.9 mg), and stir to obtain a liquid electrolyte. After heating and curing, a solid polymer electrolyte is obtained.

[0075] Battery assembly: Assemble a CR 2032 coin cell in the order of "negative electrode case - lithium sheet - electrolyte membrane - 30 μl FEC electrolyte - positive electrode sheet - gasket - shrapnel - positive electrode case". According to the test content, the electrode sheets are selected from steel sheets, lithium iron phosphate positive electrode sheets, NCM622 positive electrode sheets, lithium manganese iron phosphate positive electrode sheets, and lithium sheets.

[0076] The compositions of Examples 1 - 7 are shown in Table 3.

[0077] Table 3 Composition components of the solid polymer electrolyte

[0078]

[0079] Performance test

[0080] Preparation of the solid polymer electrolyte membrane: Pour the liquid electrolyte prepared in Example 1 onto a glass plate, let it stand and heat to cure to obtain a solid polymer electrolyte membrane. The structure is as Figure 2As shown, the solid polymer electrolyte membrane has a certain flexibility, can be applied to flexible batteries and has a certain mechanical strength.

[0081] The structure of the solid polymer electrolyte prepared in Example 1 was characterized by Fourier transform infrared spectroscopy, as Figure 3 shown. The results show that under the action of the initiator, a polymerization reaction was initiated to generate a dimethyl itaconate-polyethylene glycol methyl ether methacrylate electrolyte with a cross-linked structure. Among them, the interaction between the lithium salt and the ether bond was observed at 1100 cm -1 to broaden the peak shape of the ether bond.

[0082] The electrochemical performance was all obtained by testing with an electrochemical workstation.

[0083] Figure 4 is a graph of the ionic conductivity-temperature relationship of the solid polymer electrolyte. The polymer electrolytes in this system all have excellent ionic conductivity. Among them, the ionic conductivity of Example 1 is the highest, and the ionic conductivity at 80 °C is 9.95×10 -5 S cm -1 . The ionic conductivities of each electrolyte at different temperatures are shown in Table 4.

[0084] Table 4 Ionic conductivities of solid polymer electrolytes at different temperatures

[0085]

[0086] Figure 5 is the linear sweep voltammogram of the steel sheet / solid electrolyte / Lithium battery of Example 1; from Figure 5 it can be seen that the redox potential of Example 1 is as high as 5.6 V and is stable and does not decompose in high-voltage positive electrode batteries.

[0087] Figure 6 is the lithium ion transference number graph of the LiNi0.6Co0.2Mn0.2O2 / solid electrolyte / Lithium battery of Example 1, and the lithium ion transference number is shown as 0.33.

[0088] The charge and discharge performance of the battery was tested by a battery cycling system.

[0089] Figure 7 is the 0.1C cycling graph of the LiFePO4 / solid electrolyte / Lithium battery of Example 1 at 60 °C;

[0090] Figure 8 is the 0.1C cycling graph of the LiNi0.6Co0.2Mn0.2O2 / solid electrolyte / Lithium battery of Example 1 at 60 °C. Figure 7 and Figure 8It is shown that the solid polymer electrolyte prepared in Example 1 has good cycling performance in practical applications. When the positive electrode is lithium iron phosphate, the capacity does not decay after 100 cycles of charge and discharge at 0.1C at 60°C; even for the lithium nickel cobalt manganese oxide 622 positive electrode with a voltage as high as 4.3V, the capacity retention rate is 75% after 50 cycles under the same conditions. Therefore, the battery containing the solid polymer electrolyte prepared in Example 1 not only has good compatibility with the lithium iron phosphate positive electrode, but also can exhibit good cycling stability for high-voltage positive electrodes.

[0091] Figure 9 It is the rate performance diagram of the lithium iron phosphate / gel electrolyte / lithium battery of Example 8 at 60°C. From Figure 9 it can be seen that the capacity recovery rate from 1C charge and discharge to 0.2C charge and discharge is 72.05%, the battery has good rate performance and good reversibility.

[0092] Figure 10 It is the 0.1C cycling diagram of the lithium iron manganese phosphate / gel electrolyte / lithium battery of Example 8 at 25°C. From Figure 10 it can be seen that the battery has excellent cycling performance at room temperature and the capacity does not decay after 50 cycles.

[0093] It can be understood that the present invention is described by some embodiments. As is known to those skilled in the art, without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. Additionally, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A preparation method of a bio-based solid polymer electrolyte, characterized in that, It includes the following steps: (1) Mix polymer monomer 1, polymer monomer 2, initiator, lithium salt and additive, and stir evenly to obtain a precursor solution; (2) Add a crosslinking agent to the precursor solution and heat and cure to obtain a solid polymer electrolyte; The general structural formula of the polymer monomer 1 is formula (Ⅰ), the general structural formula of the polymer monomer 2 is formula (Ⅱ), and the general structural formula of the crosslinking agent is formula (Ⅲ). The structural formulas of formula (Ⅰ), formula (Ⅱ) and formula (Ⅲ) are as follows: Wherein, R1, R2, R3, and R4 are each independently selected from substituted or unsubstituted alkyl groups. When being substituted, the substituent is selected from halogen; the number of carbon atoms in the alkyl group is less than or equal to 20, the value range of n in formula (Ⅰ) is 17-20, and the value range of m in formula (Ⅲ) is 11-14.

2. The preparation method of a bio-based solid polymer electrolyte according to claim 1, characterized in that, The molar ratio of the polymer monomer 1, polymer monomer 2, initiator and crosslinking agent is 100:233-400:3-5:3-10. The mass of the lithium salt accounts for 0.1-50 wt% of the total mass of the solid polymer electrolyte, and the additive accounts for 0-80 wt% of the total mass of the solid polymer electrolyte.

3. The preparation method of a bio-based solid polymer electrolyte according to claim 1, characterized in that The initiator is compound 1; 4. The preparation method of a bio-based solid polymer electrolyte according to claim 1, characterized in that, In step (2), the curing heating temperature is 40-90 °C, and the heating time is 24-96 h.

5. The preparation method of a bio-based solid polymer electrolyte according to claim 1, characterized in that, In step (2), a plasticizer is also added. The plasticizer accounts for 0-10 wt% of the sum of the masses of each reactant, and the plasticizer is selected from any one of compound 2 to compound 3; 6. The preparation method of a bio-based solid polymer electrolyte according to claim 1, wherein The lithium salt is selected from one or more of lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluorobis(oxalato)phosphate, lithium oxalate phosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium bis(difluoromethanesulfonyl)imide salt and lithium bis(trifluoromethylsulfonyl)imide.

7. The preparation method of a bio-based solid polymer electrolyte according to claim 1, characterized in that, The additive is selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylic acid, polyacrylonitrile, poly(methyl methacrylate carbonate), polyethylene oxide, polyethylene, polypropylene, polyamide, polyimide, polyvinyl alcohol, polyvinyl butyral, polysiloxane, polytetrafluoroethylene, inorganic filler oxide solid electrolyte, sulfide solid electrolyte, silicon monoxide, silicon dioxide, titanium oxide, zirconium oxide, aluminum oxide, boehmite, montmorillonite, tetraethylene glycol dimethyl ether, plastic crystal.

8. A solid polymer electrolyte prepared by the preparation method of the bio-based solid polymer electrolyte according to any one of claims 1-7.

9. Use of the solid polymer electrolyte according to claim 8 in a lithium battery, characterized in that, The lithium battery includes a positive electrode, a negative electrode and a separator, and further includes the solid polymer electrolyte according to claim 8 disposed between the positive electrode and the negative electrode.

10. A bio-based gel polymer electrolyte, characterized in that, It includes the solid polymer electrolyte according to claim 8 and a lithium-ion battery electrolyte; the lithium-ion battery electrolyte includes a lithium salt, a non-aqueous organic solvent and an additive; The lithium salt is at least one of lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium difluorophosphate, lithium difluoro(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, lithium oxalato phosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium bis(difluoromethanesulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide, and the content of the lithium salt accounts for 0.1 to 25.0 wt% of the total mass of the lithium ion battery electrolyte; The non-aqueous organic solvent is at least one of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate, γ-butyrolactone, ethylene glycol dimethyl ether, tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, dimethyl sulfoxide, dimethyl sulfone, acetone, and N,N-dimethylformamide, and the content of the non-aqueous organic solvent accounts for 20.0 to 70.0 wt% of the total mass of the lithium ion battery electrolyte; The additive is at least one of fluorinated ethylene carbonate, vinylene carbonate, 1,3-propane sultone, ethylene sulfate, methylene methanedisulfonate, propylene sultone, citraconic anhydride, succinonitrile, adiponitrile, ethylene glycol diether, and hexane trinitrile, and the content of the additive accounts for 0.1 to 20.0 wt% of the total mass of the lithium ion battery electrolyte.

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