Gel polymer electrolyte membrane, preparation method thereof and semi-solid battery

Abstract

The invention provides a gel polymer electrolyte membrane, a preparation method thereof and a semi-solid battery, and belongs to the technical field of secondary batteries. The gel polymer electrolyte membrane comprises a gel polymer matrix, an electrolyte and a first additive, and the first additive is poly (2, 5-dihydroxyaniline) and / or poly (3, 6-dihydroxyaniline); and the gel polymer electrolyte membrane is of a microporous structure. According to the gel polymer electrolyte membrane disclosed by the embodiment of the invention, poly (3, 6-dihydroxyaniline) and / or poly (2, 5-dihydroxyaniline) are / is introduced into the gel polymer electrolyte membrane, so that the ionic conductivity of a gel polymer matrix can be improved, and the cyclic reversibility of the gel polymer matrix is improved, and therefore, the gel polymer electrolyte membrane disclosed by the embodiment of the invention can enable a semi-solid battery to have excellent rate capability.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a gel polymer electrolyte membrane, its preparation method, and a semi-solid battery. Background Technology

[0002] Batteries, as an important energy storage device, are widely used in new energy vehicles, energy storage cabinets, consumer electronics and other fields. Most of the electrolytes used are organic liquid electrolytes, which pose risks of volatility, flammability and leakage.

[0003] In response to the risks associated with liquid electrolytes, the concepts of solid-state batteries and quasi-solid-state batteries have been proposed in related technologies. These batteries use solid polymer electrolytes, contain no organic liquids, are safe, and can be made into any shape. However, their ionic conductivity is far lower than that of liquid electrolytes, which does not meet the requirements for applications.

[0004] Related technologies also propose semi-solid-state batteries, which can use pure gel polymer electrolytes. Although pure gel polymer electrolytes combine the good flexibility and easy diffusion of solid electrolytes, overcoming the disadvantages of electrolytes easily generating flammable substances on the electrode surface and leakage, their conductivity is still lower than that of liquid electrolytes (10...). -2 S·cm -1 The low concentration of ions results in a significant reduction in the high-current discharge and low-temperature performance of lithium-ion batteries assembled from them. Due to the presence of small molecule solvents, pure gel polymer electrolytes have drawbacks such as high volatility, poor electrochemical and thermal stability, low mechanical strength, and poor electrode-electrolyte interface stability. In addition, the high moisture content required during production and preparation leads to large investment in production equipment and high costs.

[0005] Furthermore, pure gel polymer electrolytes synthesized using in-situ polymerization in related technologies suffer from uneven gel distribution at the electrode interface, poor interfacial compatibility between the electrolyte and the electrode, resulting in high ion transport resistance, low ionic conductivity at room temperature, severely hindering the rapid transport of lithium ions, slow charge and discharge rates at room temperature, and poor power performance. In addition, although pure gel polymer electrolytes have a jelly-like consistency and poor fluidity, they only fix the electrolyte within the polymer framework; not all electrolyte is fixed, and some free electrolyte remains. During thermal runaway or overcharge tests, a large amount of heat is still released, resulting in poor safety performance.

[0006] Therefore, it is necessary to design a gel polymer electrolyte membrane, its preparation method, and a semi-solid battery. This gel polymer electrolyte membrane can be used to improve the rate performance and safety performance of the battery. Summary of the Invention

[0007] This invention aims to at least partially address one of the technical problems in related technologies. To this end, embodiments of this invention provide a gel polymer electrolyte membrane, a method for preparing the same, and a semi-solid-state battery.

[0008] In a first aspect, embodiments of the present invention provide a gel polymer electrolyte membrane, the gel polymer electrolyte membrane comprising a gel polymer matrix, an electrolyte, and a first additive, wherein the first additive is poly(2,5-dihydroxyaniline) and / or poly(3,6-dihydroxyaniline); the gel polymer electrolyte membrane has a microporous structure.

[0009] The advantages and technical effects of the gel polymer electrolyte membrane in this invention are as follows:

[0010] (1) Introducing poly(3,6-dihydroxyaniline) and / or poly(2,5-dihydroxyaniline) into the gel polymer electrolyte membrane, poly(3,6-dihydroxyaniline) and / or poly(2,5-dihydroxyaniline) have a two-electron two-proton transport mechanism, which can improve the ionic conductivity of the gel polymer matrix and increase the cycle reversibility of the gel polymer matrix. Therefore, the gel polymer electrolyte membrane of the present invention can enable the semi-solid battery to have excellent rate performance.

[0011] (2) Poly(3,6-dihydroxyaniline) and / or poly(2,5-dihydroxyaniline) filled in the gel polymer matrix can also inhibit the crystallization of the gel polymer matrix, promote the ion migration ability of the gel polymer matrix, improve the ionic conductivity of the gel polymer matrix, and increase the cycle reversibility of the gel polymer matrix. Therefore, the gel polymer electrolyte membrane of the present invention can make the semi-solid battery have excellent rate performance.

[0012] (3) The gel polymer electrolyte membrane contains poly(2,5-dihydroxyaniline) and / or 3,6-dihydroxyaniline. Poly(2,5-dihydroxyaniline) and / or 3,6-dihydroxyaniline have a special quinone structure, which can easily interact with the gel polymer matrix and electrolyte to form a highly conductive polymer interface layer. This can improve the ionic conductivity of the gel polymer matrix and increase the cycle reversibility of the gel polymer matrix. Therefore, the gel polymer electrolyte membrane of the present invention can enable the semi-solid battery to have excellent rate performance.

[0013] (4) The gel polymer electrolyte membrane contains poly(2,5-dihydroxyaniline) and / or 3,6-dihydroxyaniline, which forms pores in the gel polymer electrolyte membrane. The electrolyte enters the pores of the gel polymer electrolyte membrane, preventing the electrolyte from flowing everywhere, thus giving the semi-solid battery excellent safety performance.

[0014] (5) Compared with the pure gel polymer electrolyte synthesized by in-situ polymerization in related technologies, the gel polymer electrolyte membrane of the present invention does not require the addition of an initiator, and the resulting membrane has a uniform thickness, which can better perform the battery performance, while avoiding the negative impact of residual initiator on battery performance.

[0015] In some embodiments, the mass ratio of the first additive to the gel polymer matrix is ​​(0.1 to 0.4):1.

[0016] In some embodiments, the gel polymer electrolyte membrane further includes a second additive, which is a hydrofluoroether.

[0017] In some embodiments, the mass ratio of the second additive to the gel polymer matrix is ​​(0.1 to 1):1.

[0018] In some embodiments, the gel polymer matrix includes at least one of polyvinylidene fluoride, polyethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyacrylonitrile.

[0019] Secondly, embodiments of the present invention provide a method for preparing a gel polymer electrolyte membrane, comprising the following steps:

[0020] S1. Mix the solvent, pore-forming agent, the first additive and the gel polymer matrix, and then disperse them to obtain the casting liquid;

[0021] S2. The mixed solution is poured onto a substrate and then baked under vacuum conditions to obtain a microporous membrane;

[0022] S3. The microporous membrane is transferred to a vacuum glove box and immersed in the electrolyte for activation to obtain the gel polymer electrolyte membrane described in the first aspect.

[0023] The advantages and technical effects of the preparation method of this invention are as follows:

[0024] (1) In this embodiment of the invention, a microporous membrane was prepared by phase transition method. The microporous membrane was then activated by immersing it in an electrolyte to obtain a gel polymer electrolyte membrane. The process is simple and practical. The obtained gel polymer electrolyte membrane has a high room temperature ionic conductivity.

[0025] (2) Compared with the gel polymer electrolyte membrane obtained by in-situ polymerization, the gel polymer electrolyte membrane prepared in the embodiments of the present invention has higher mechanical strength and more uniform thickness, avoiding the problem of uneven gel distribution in the cell during in-situ polymerization, and reducing the risk of lithium plating caused by the blockage of lithium ion transport channels during charging and discharging.

[0026] (3) The preparation method of the present invention is flexible in operation. Except for impregnation and activation, other process steps do not need to be in a strict drying environment, which greatly reduces the production cost.

[0027] In some embodiments, step S1 specifically includes the following steps:

[0028] S1-1. Mix the solvent and the pore-forming agent to obtain a first mixed solution;

[0029] S1-2. Mix the first additive and the first mixed solution, and then perform a first dispersion treatment to obtain a second mixed solution;

[0030] S1-3. Mix the gel polymer matrix and the second mixed solution, and then perform a second dispersion treatment to obtain the casting liquid.

[0031] Optionally, the solvent is at least one selected from dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, trifluoromethylchloroform, and trifluoromethane.

[0032] Optionally, the pore-forming agent is at least one of glycerol, polystyrene, and polypropylene.

[0033] Optionally, the volume ratio of the solvent to the pore-forming agent is (10-15):1.

[0034] Optionally, the mass ratio of the first additive to the volume ratio of the first mixed solution is (2-8) g:(20-25) mL.

[0035] Optionally, the mass ratio of the first additive to the gel polymer matrix is ​​(0.1 to 0.4):1.

[0036] Optionally, the first dispersion treatment includes ultrasonic dispersion for 8 to 12 minutes, followed by stirring at 60 to 100°C for 0.5 to 1.5 hours.

[0037] Optionally, the second dispersion treatment includes stirring for 3 to 5 hours under heating conditions of 60 to 100°C.

[0038] Optionally, the baking temperature is 100–120°C, and the baking time is 20–30 hours.

[0039] Optionally, the thickness of the microporous membrane is 80–200 μm.

[0040] In some embodiments, step S2 further includes: mixing the second additive with the electrolyte to obtain a modified electrolyte; correspondingly, step S3 involves transferring the microporous membrane to a vacuum glove box and immersing it in the modified electrolyte for activation to obtain the gel polymer electrolyte membrane.

[0041] Optionally, the mass ratio of the second additive to the electrolyte is 1:(50-100).

[0042] Thirdly, embodiments of the present invention provide a semi-solid battery, including the gel polymer electrolyte membrane described in the first aspect.

[0043] The advantages and technical effects of the semi-solid-state battery in this invention are as follows:

[0044] The semi-solid-state battery of this invention has excellent safety performance and rate performance. Attached Figure Description

[0045] Figure 1 The structural formula of 2,5-dihydroxyaniline prepared in Example 1 is shown;

[0046] Figure 2 The structural formula of 3,6-dihydroxyaniline prepared in Example 5 is shown;

[0047] Figure 3 The structural formula of meta-aramid is shown;

[0048] Figure 4 The FE-SEM images of the microporous gel polymer electrolyte membrane prepared in Example 2 at different magnifications are shown. Detailed Implementation

[0049] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0050] In a first aspect, embodiments of the present invention provide a gel polymer electrolyte membrane, the gel polymer electrolyte membrane comprising a gel polymer matrix, an electrolyte, and a first additive, wherein the first additive is poly(2,5-dihydroxyaniline) and / or poly(3,6-dihydroxyaniline); the gel polymer electrolyte membrane has a microporous structure, and the pore size of the micropores can be, for example, 0.01 μm, 0.05 μm, 0.1 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, etc.

[0051] Introducing poly(3,6-dihydroxyaniline) and / or poly(2,5-dihydroxyaniline) into the gel polymer electrolyte membrane, which possesses a two-electron, two-proton transport mechanism, can improve the ionic conductivity of the gel polymer matrix and increase its cycle reversibility. Therefore, the gel polymer electrolyte membrane of this invention can enable semi-solid-state batteries to have excellent rate performance.

[0052] The filling of poly(3,6-dihydroxyaniline) and / or poly(2,5-dihydroxyaniline) into the gel polymer matrix can also inhibit the crystallization of the gel polymer matrix, promote the ion migration ability of the gel polymer matrix, improve the ionic conductivity of the gel polymer matrix, and increase the cycle reversibility of the gel polymer matrix. Therefore, the gel polymer electrolyte membrane of the present invention can enable the semi-solid battery to have excellent rate performance.

[0053] The gel polymer electrolyte membrane contains poly(2,5-dihydroxyaniline) and / or 3,6-dihydroxyaniline. Poly(2,5-dihydroxyaniline) and / or 3,6-dihydroxyaniline have a special quinone structure, which readily interacts with the gel polymer matrix and electrolyte to form a highly conductive polymer interface layer. This can improve the ionic conductivity of the gel polymer matrix and increase its cycle reversibility. Therefore, the gel polymer electrolyte membrane of the present invention can enable semi-solid-state batteries to have excellent rate performance.

[0054] The gel polymer electrolyte membrane contains poly(2,5-dihydroxyaniline) and / or 3,6-dihydroxyaniline, which forms pores in the gel polymer electrolyte membrane. The electrolyte enters into the pores of the gel polymer electrolyte membrane, preventing the electrolyte from flowing everywhere, thus giving the semi-solid battery excellent safety performance.

[0055] Compared with pure gel polymer electrolytes synthesized by in-situ polymerization in related technologies, the gel polymer electrolyte membrane of the present invention does not require the addition of an initiator, and the resulting membrane layer has a uniform thickness, which can better enhance the performance of the battery, while avoiding the negative impact of residual initiator on battery performance.

[0056] In some embodiments, the mass ratio of the first additive to the gel polymer matrix is ​​(0.1–0.4):1, for example, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, etc. When this mass ratio is within the above range, it is beneficial to improve the ionic conductivity of the gel polymer electrolyte membrane. Preferably, the mass ratio of the first additive to the gel polymer matrix is ​​(0.15–0.25):1.

[0057] In some embodiments, the gel polymer electrolyte membrane further includes a second additive, which is hydrofluoroether. The presence of a small amount of hydrofluoroether in the gel polymer electrolyte membrane can reduce the viscosity of the electrolyte and accelerate ion conduction; additionally, it can also accelerate the wetting rate of the electrolyte and improve ionic conductivity.

[0058] In some embodiments, the mass ratio of the second additive to the gel polymer matrix is ​​(0.1 to 1):1, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, etc. This mass ratio within the above range is beneficial for improving the ionic conductivity of the gel polymer electrolyte membrane.

[0059] The gel polymer electrolyte membrane of this invention does not have any particular limitations on the gel polymer matrix, as long as it belongs to the field of secondary batteries. For example, the gel polymer matrix may include, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polyethylene (PEO), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-PHFP), and polyacrylonitrile (PAN).

[0060] Secondly, embodiments of the present invention provide a method for preparing a gel polymer electrolyte membrane, comprising the following steps:

[0061] S1. Mix the solvent, pore-forming agent, the first additive and the gel polymer matrix, and then disperse them to obtain the casting liquid;

[0062] S2. The mixed solution is poured onto a substrate and then baked under vacuum conditions to obtain a microporous membrane;

[0063] S3. The microporous membrane is transferred to a vacuum glove box and immersed in the electrolyte for activation to obtain the gel polymer electrolyte membrane described in the first aspect.

[0064] In this embodiment of the invention, a microporous membrane was prepared by phase transition method. The microporous membrane was then activated by immersing it in an electrolyte to obtain a gel polymer electrolyte membrane. The process is simple, highly practical, and the resulting gel polymer electrolyte membrane has a high room temperature ionic conductivity.

[0065] Compared to gel polymer electrolyte membranes obtained through in-situ polymerization, the gel polymer electrolyte membranes prepared in this embodiment of the invention have higher mechanical strength and more uniform thickness, avoiding the problem of uneven gel distribution in the cell during in-situ polymerization, and reducing the risk of lithium plating caused by blockage of lithium ion transport channels during charging and discharging.

[0066] The preparation method of this invention is flexible in operation. Except for impregnation and activation, other process steps do not need to be carried out in a strictly dry environment, which greatly reduces production costs.

[0067] In some embodiments, step S1 specifically includes the following steps:

[0068] S1-1. Mix the solvent and the pore-forming agent to obtain a first mixed solution;

[0069] S1-2. Mix the first additive and the first mixed solution, and then perform a first dispersion treatment to obtain a second mixed solution;

[0070] S1-3. Mix the gel polymer matrix and the second mixed solution, and then perform a second dispersion treatment to obtain the casting liquid.

[0071] The above steps S1-1 to S1-3 involve mixing various raw materials in stages, which is beneficial for uniform mixing and thus helps to improve the uniformity of the first additive dispersion in the gel polymer matrix.

[0072] Optionally, the solvent is at least one selected from dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, trifluoromethylchloroform, and trifluoromethane.

[0073] Optionally, the pore-forming agent is at least one of glycerol, polystyrene, and polypropylene.

[0074] Optionally, the volume ratio of the solvent to the pore-forming agent is (10-15):1, for example, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, etc. Due to the presence of a certain amount of pore-forming agent, a microporous membrane is formed in step S2. The gel polymer electrolyte membrane formed in step S3 also has a microporous structure. In addition, the impregnation and activation in step S3 fills the pores of the microporous membrane with electrolyte, which is more conducive to rapid ion transport.

[0075] Optionally, the mass ratio of the first additive to the volume ratio of the first mixed solution is (2-8) g:(20-25) mL. This ratio, within the above range, is beneficial for the uniform dispersion of the first additive.

[0076] Optionally, the mass ratio of the first additive to the gel polymer matrix is ​​(0.1 to 0.4):1.

[0077] Optionally, the first dispersion treatment includes ultrasonic dispersion for 8–12 minutes, followed by stirring at 60–100°C for 0.5–1.5 hours. This facilitates uniform dispersion of the first additive in the solvent.

[0078] Optionally, the second dispersion treatment includes stirring for 3 to 5 hours under heating conditions at 60–100°C. This facilitates uniform mixing of the first additive with the gel polymer matrix.

[0079] Optionally, the baking temperature is 100–120°C, such as 100°C, 105°C, 110°C, 115°C, 120°C, etc., and the baking time is 20–30 hours, such as 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, etc. The above baking treatment allows the pore-forming agent and solvent to evaporate completely, resulting in a microporous membrane.

[0080] Optionally, the thickness of the microporous membrane is 80–200 μm, such as 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, etc.

[0081] In some embodiments, step S2 further includes: mixing the second additive with the electrolyte to obtain a modified electrolyte; correspondingly, step S3 involves transferring the microporous membrane to a vacuum glove box and immersing it in the modified electrolyte for activation to obtain the gel polymer electrolyte membrane.

[0082] Optionally, the mass ratio of the second additive to the electrolyte is 1:(50-100), for example, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, etc. This mass ratio within the above range is beneficial for reducing the viscosity of the electrolyte, thereby improving the ionic conductivity of the gel polymer electrolyte membrane.

[0083] Thirdly, embodiments of the present invention provide a semi-solid battery, including the gel polymer electrolyte membrane described in the first aspect.

[0084] Because of the use of the gel polymer electrolyte membrane described in the first aspect, the semi-solid battery of the present invention has excellent safety performance and rate performance.

[0085] The embodiments of the present invention do not impose any particular restrictions on the type of semi-solid-state battery. For example, the positive electrode can be a ternary positive electrode material system or a lithium iron phosphate positive electrode material system, etc.; the negative electrode can be a graphite system or a silicon-based system, etc.

[0086] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0087] Example 1

[0088] Step 1. Preparation of poly-2,5-dihydroxyaniline:

[0089] ① Prepare 0.1 mol / L 2,5-dimethoxyaniline using 0.5 mol / L hydrochloric acid solution.

[0090] ② Add 2,5-dimethoxyaniline to a three-necked flask, stir under an ice-water bath (<5℃), and add ammonium persulfate solution dropwise (molar ratio n(ammonium persulfate):n(2,5-dimethoxyaniline) = 1:1) over a period of 1 hour. A dark green precipitate will form. After the addition is complete, stir at room temperature for 24 hours.

[0091] ③ After the reaction in step ② is complete, let it stand for half an hour, filter it, wash the filter cake with 0.5 mol / L hydrochloric acid until the filtrate is colorless, and then wash the filter cake with water until the pH of the filtrate is 6.

[0092] ④ Place the filter cake in a desiccator and dry it at room temperature until constant weight. Remove the reaction product from the filter cake and grind it into powder using a ball mill to obtain poly(2,5-dihydroxyaniline). The structural formula of poly(2,5-dihydroxyaniline) is as follows: Figure 1 As shown, the weight-average molecular weight of this poly(2,5-dihydroxyaniline) is 464.

[0093] Step 2. First, add 1.60 mL of glycerol (pore-forming agent) to 21.1 mL of dimethylformamide solution (solvent), and stir with a glass rod for 10 minutes to form a homogeneous first mixed solution.

[0094] Step 3. Add 2g of poly2,5-dihydroxyaniline to the first mixed solution obtained in Step 1, first ultrasonically disperse it for 10 minutes, and then stir it in a stirrer. During the stirring process, raise the temperature to 80℃ and continue for 1 hour. After the dispersion is uniform, the second mixed solution is obtained. Gradually add 20g of polyvinylidene fluoride (PVDF) to the second mixed solution, and continue stirring at 80℃ for 4 hours to form a uniform third mixed solution, which is the casting liquid.

[0095] Step 4. Pour the third mixed solution onto a smooth glass plate and place it in a vacuum oven. Bake at 110°C for 24 hours. After the pore-forming agent and solvent evaporate, a microporous membrane with a thickness of 150 μm can be obtained.

[0096] Step 5. Weigh 5g of electrolyte in a vacuum glove box. The electrolyte consists of solvent, electrolyte additives, and electrolyte. The solvent is ethylene carbonate (EC) and dimethyl carbonate (DMC), with a volume ratio of EC to DMC of 1:1.3. The electrolyte additives are 1,3-propanesulfonate lactone (PS), vinyl sulfate (DTD), and vinylene carbonate (VC), with a mass ratio of PS, DTD, and VC of 6.4:3.6:1. The electrolyte lithium salt in the electrolyte is LiPF6, and the concentration of lithium salt in the electrolyte is 0.9 mol / L. Add 50 mg of hydrofluoroether to the electrolyte and mix well to obtain the modified electrolyte.

[0097] Step 6. Transfer the microporous membrane to a vacuum glove box and immerse it in the modified electrolyte for 3 hours. After the substrate has fully absorbed the modified electrolyte, remove it to obtain a microporous gel polymer electrolyte membrane. In this microporous gel polymer electrolyte membrane, the mass ratio of electrolyte to gel polymer matrix polyvinylidene fluoride (PVDF) is 5:1; the mass ratio of poly(2,5-dihydroxyaniline) to gel polymer matrix PVDF is 0.1:1; and the mass ratio of hydrofluoroether to gel polymer matrix PVDF is 0.05:1. This microporous gel polymer electrolyte membrane has a microporous structure with a pore size of 0.01–2.5 μm.

[0098] Step 7. Dissolve PVDF (binder) in N-methylpyrrolidone (NMP) to form a paste, then mix the ternary cathode material NCM622 (Ronbay Technology), conductive agents (SP and CNT) with the paste evenly to obtain a cathode slurry; coat the cathode slurry onto the surface of aluminum foil and dry to obtain a cathode sheet.

[0099] Weigh 8g of PVDF (adhesive) and add it to 30g of N-methylpyrrolidone (NMP). Stir at high speed for 1 hour at room temperature to form a clear and transparent adhesive solution. Add 12g of meta-aramid (structural formula as shown) to the adhesive solution. Figure 3 As shown in the figure, continue stirring at room temperature to ensure thorough mixing. Adjust the viscosity of the adhesive to 700 mPa·s. The mass fraction of meta-aramid in the adhesive is 24%. The adhesive is then uniformly coated onto the surface of the positive electrode using a printing technique, with a coating thickness of approximately 2 μm. The electrode is then baked at 110°C for 30 minutes, followed by roll pressing to obtain a pretreated positive electrode. After pretreatment, the positive electrode is coated with a mixture of meta-aramid / PVDF. Meta-aramid exhibits good electrolyte wettability, rapid liquid absorption, and high liquid retention, effectively improving the contact performance between the electrolyte and the positive electrode interface. Simultaneously, meta-aramid possesses high-temperature resistance and insulation properties, enhancing battery safety.

[0100] Step 8. Assemble and package the pretreated positive electrode, microporous gel polymer electrolyte membrane and graphite negative electrode (5 layers of negative electrode and 4 layers of pretreated positive electrode) to obtain a soft-pack laminated semi-solid cell.

[0101] Example 2

[0102] The preparation method of this embodiment is the same as that of Example 1. The difference is that the mass of poly2,5-dihydroxyaniline in step 3 is 4g, and the mass ratio of poly2,5-dihydroxyaniline to polyvinylidene fluoride (PVDF) in the microporous gel polymer electrolyte membrane is 0.2:1.

[0103] Example 3

[0104] The preparation method of this embodiment is the same as that of Example 1. The difference is that the mass of poly2,5-dihydroxyaniline in step 3 is 6g, and the mass ratio of poly2,5-dihydroxyaniline to polyvinylidene fluoride (PVDF) in the microporous gel polymer electrolyte membrane is 0.3:1.

[0105] Example 4

[0106] The preparation method of this embodiment is the same as that of Example 1. The difference is that the mass of poly2,5-dihydroxyaniline in step 3 is 8g, and the mass ratio of poly2,5-dihydroxyaniline to polyvinylidene fluoride (PVDF) in the microporous gel polymer electrolyte membrane is 0.4:1.

[0107] Example 5

[0108] The preparation method in this embodiment is the same as in Example 1, except that in step 1, the preparation of poly3,6-dihydroxyaniline, ① 2,5-dimethoxyaniline is replaced with 3,6-dimethoxyaniline, and the structural formula of the obtained poly3,6-dihydroxyaniline is as follows. Figure 2 As shown; in step 3, poly(2,5-dihydroxyaniline) is replaced with poly(3,6-dihydroxyaniline), and the mass ratio of poly(3,6-dihydroxyaniline) to polyvinylidene fluoride (PVDF) in the microporous gel polymer electrolyte membrane is 0.1:1.

[0109] Example 6

[0110] The preparation method in this embodiment is the same as that in Example 5, except that the mass of poly(3,6-dihydroxyaniline) in step 3 is 4g, and the mass ratio of poly(3,6-dihydroxyaniline) to polyvinylidene fluoride (PVDF) in the microporous gel polymer electrolyte membrane is 0.2:1.

[0111] Example 7

[0112] The preparation method in this embodiment is the same as that in Example 5, except that the mass of poly(3,6-dihydroxyaniline) in step 3 is 6g, and the mass ratio of poly(3,6-dihydroxyaniline) to polyvinylidene fluoride (PVDF) in the microporous gel polymer electrolyte membrane is 0.3:1.

[0113] Example 8

[0114] The preparation method in this embodiment is the same as that in Example 5, except that the mass of poly(3,6-dihydroxyaniline) in step 3 is 8g, and the mass ratio of poly(3,6-dihydroxyaniline) to polyvinylidene fluoride (PVDF) in the microporous gel polymer electrolyte membrane is 0.4:1.

[0115] Example 9

[0116] The preparation method in this embodiment is the same as that in Example 1, except that in step 7, the ternary cathode material NCM622 (Rongbai Technology) is replaced with lithium iron phosphate cathode material.

[0117] Example 10

[0118] The preparation method in this embodiment is the same as that in embodiment 1, except that in step 8, the graphite negative electrode sheet is replaced with a silicon-oxygen negative electrode sheet.

[0119] Example 11

[0120] The preparation method of this embodiment is the same as that of embodiment 1. The difference is that in step 7, the ternary cathode material NCM622 (Rongbai Technology) is replaced with the high-nickel ternary cathode material NCM811 (Rongbai Technology), and in step 8, the graphite anode sheet is replaced with the silicon-carbon anode sheet.

[0121] Example 12

[0122] The preparation method of this embodiment is the same as that of Example 2, except that in step 5, hydrofluoric ether is not added to the electrolyte; and in step 6, the microporous membrane is transferred to a vacuum glove box and soaked in the electrolyte for 3 hours. After the substrate has fully absorbed the electrolyte, it is taken out to obtain a microporous gel polymer electrolyte membrane.

[0123] Comparative Example 1

[0124] The comparative example is the same as Example 1, except that in step 3, the mass of poly(2,5-dihydroxyaniline) is 0.

[0125] Comparative Example 2

[0126] The comparative example is the same as Example 5, except that in step 3, the mass of poly(3,6-dihydroxyaniline) is 0.

[0127] Comparative Example 3

[0128] Step 1. Dissolve PVDF (binder) in N-methylpyrrolidone (NMP) to form a paste. Then mix the ternary cathode material NCM622 (Ronbay Technology), conductive agents (SP and CNT) with the paste to obtain a cathode slurry. Coat the cathode slurry onto the surface of aluminum foil and dry it to obtain a cathode sheet.

[0129] Step 2. Stack and encapsulate the positive electrode, PP separator and graphite negative electrode (5 layers of negative electrode and 4 layers of pretreated positive electrode) to obtain a dry cell. Inject sufficient liquid ternary electrolyte to obtain a soft-pack battery.

[0130] Comparative Example 4

[0131] Step 1. Dissolve PVDF (binder) in N-methylpyrrolidone (NMP) to form a slurry. Then mix lithium iron phosphate cathode material, conductive agent (SP and CNT) with the slurry to obtain cathode slurry. Coat the cathode slurry onto the surface of aluminum foil and dry to obtain cathode sheet.

[0132] Step 2. Stack and encapsulate the positive electrode, PP separator and graphite negative electrode (5 layers of negative electrode and 4 layers of pretreated positive electrode) to obtain a dry cell, inject sufficient lithium iron phosphate electrolyte to obtain a soft pack battery.

[0133] Comparative Example 5

[0134] The preparation method of this comparative example is the same as that of comparative example 3, except that the same amount of gel electrolyte precursor is injected. The gel electrolyte precursor is a mixture of electrolyte, gel monomer (manufacturer: Shenzhen Guyineng Technology Co., Ltd., model: GA-20) and initiator azobisisobutyronitrile (AIBN). The resulting soft-pack battery is first left to stand at room temperature for 24 hours, and after being fully impregnated, it is cured at 60°C for 3 hours to obtain the polymerized soft-pack battery.

[0135] Comparative Example 6

[0136] The comparative example is the same as that in Example 12, except that in step 3, the mass of poly(2,5-dihydroxyaniline) is 0.

[0137] Material characterization and test data

[0138] (1) The ionic conductivity of the microporous gel polymer electrolyte membranes prepared in Examples 1-8 and Comparative Examples 1-2 was tested, and the results are shown in Table 1.

[0139] (2) The first discharge capacity, first coulombic efficiency and capacity retention after 300 cycles of the soft-pack batteries made in the above embodiments and comparative examples were tested, and the results are shown in Table 2.

[0140] Table 1. Ionic conductivity of the microporous gel polymer electrolyte membranes prepared in Examples 1-8 and Comparative Examples 1-2

[0141]

[0142] Table 2. Electrochemical performance test results of the pouch batteries prepared in the above embodiments and comparative examples.

[0143]

[0144]

[0145] Figure 4The FE-SEM images of the microporous gel polymer electrolyte membrane prepared in Example 2 at different magnifications are shown. Figure 4 As can be seen from A, the surface of the microporous gel polymer electrolyte membrane prepared in Example 2 has abundant micropores, and the pores are evenly and densely distributed. Figure 4 As can be seen from B, the micropores have good interconnectivity, which can greatly improve the electrolyte ion conductivity.

[0146] Examples 1-12 show the preparation of microporous membranes by phase transition method. Appropriate amounts of poly(2,5-dihydroxyaniline) or poly(3,6-dihydroxyaniline) were added to PVDF. After drying, the microporous membranes were immersed and activated in a modified electrolyte to obtain microporous gel polymer electrolyte membranes. The ionic conductivity of these microporous gel polymer electrolyte membranes was significantly improved compared to pure gel polymer electrolyte membranes (Comparative Example 1, Comparative Example 2, or Comparative Example 6).

[0147] The microporous gel polymer electrolyte membranes prepared in Examples 2 and 6 have electronic conductivity below 10. - 10 S·cm -1 It is orders of magnitude larger and can directly replace the use of a separator to separate the positive and negative electrodes without causing a short circuit in the battery.

[0148] In addition, the preparation methods of Examples 1 to 12 are simple and have low environmental requirements.

[0149] In Examples 1-11, an appropriate amount of hydrofluoroether was added to the electrolyte. Hydrofluoroether has the characteristics of high flash point, low surface tension, low viscosity and low solidification temperature, which can ensure the compatibility of its molecules with the battery interior, effectively reduce the viscosity of the electrolyte and accelerate the lithium-ion transport rate.

[0150] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0151] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A gel polymer electrolyte film, characterized by, The gel polymer electrolyte film comprises a gel polymer matrix, an electrolyte, and a first additive, wherein the first additive is poly-2,5-dihydroxyaniline and / or poly-3,6-dihydroxyaniline, and the gel polymer electrolyte film is a microporous structure.

2. The gel polymer electrolyte membrane according to claim 1, characterized by, The mass ratio of the first additive to the gel polymer matrix is (0.1-0.4):

1.

3. The gel polymer electrolyte membrane according to claim 1, characterized by, The gel polymer electrolyte film further comprises a second additive, and the second additive is a hydrofluoroether.

4. The gel polymer electrolyte membrane according to claim 3, characterized by, The mass ratio of the second additive to the gel polymer matrix is (0.1-1):

1.

5. The gel polymer electrolyte membrane according to any one of claims 1 to 4, characterized by, The gel polymer matrix comprises at least one of polyvinylidene fluoride, polyethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyacrylonitrile.

6. The method for producing a gel polymer electrolyte film according to any one of claims 1 to 5, characterized by, The method comprises the following steps: S1. mixing a solvent, a pore-forming agent, the first additive, and the gel polymer matrix, and then performing a dispersion treatment to obtain a pouring solution; S2. pouring the mixed solution on a substrate, and then performing an oven treatment under vacuum to obtain a microporous membrane; S3. transferring the microporous membrane to a vacuum glove box, and performing an immersion activation in the electrolyte to obtain the gel polymer electrolyte film.

7. The production method according to claim 6, characterized by, Step S1 specifically comprises the following steps: S1-1. mixing the solvent and the pore-forming agent to obtain a first mixed solution; S1-2. mixing the first additive and the first mixed solution, and then performing a first dispersion treatment to obtain a second mixed solution; S1-3. mixing the gel polymer matrix and the second mixed solution, and then performing a second dispersion treatment to obtain the pouring solution.

8. The preparation method according to claim 7, characterized in that, The solvent is at least one of dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, trifluoromethyl chloroform, and trifluoromethane; Optionally, the pore-forming agent is at least one of glycerol, polystyrene, and polypropylene; Optionally, the volume ratio of the solvent to the pore-forming agent is (10-15):1; Optionally, the mass of the first additive to the volume of the first mixed solution is (2-8) g:(20-25) mL; Optionally, the mass ratio of the first additive to the gel polymer matrix is (0.1-0.4):

1. Optionally, the first dispersion treatment comprises ultrasonic dispersion for 8-12 minutes, and then stirring at 60-100°C for 0.5-1.5 hours; Optionally, the second dispersion treatment comprises stirring at 60-100°C for 3-5 hours; Optionally, the temperature of the oven treatment is 100-120°C, and the time of the oven treatment is 20-30 hours; Optionally, the thickness of the microporous membrane is 80-200 μm.

9. The method of any one of claims 6 to 8, wherein the method further comprises, Step S2 further comprises mixing the second additive with the electrolyte to obtain a modified electrolyte; correspondingly, step S3 is transferring the microporous membrane to a vacuum glove box, and performing an immersion activation in the modified electrolyte to obtain the gel polymer electrolyte film; Optionally, the mass ratio of the second additive to the electrolyte is 1:(50-100).

10. A semi-solid battery, characterized by, The gel polymer electrolyte film according to any one of claims 1-4.

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