In-situ polymerization gel solid electrolyte based on electrostatic spinning membrane and preparation method thereof

Abstract

The embodiment of the invention relates to an in-situ polymerization gel solid electrolyte based on an electrostatic spinning membrane and a preparation method of the in-situ polymerization gel solid electrolyte. Firstly, an electrostatic spinning diaphragm and an ionic solution are prepared; the ionic solution comprises a lithium salt, a polymer monomer and an initiator; the electrostatic spinning diaphragm is prepared by a coaxial electrostatic spinning technology, and the electrostatic spinning diaphragm contains uniformly distributed inorganic ceramic solid electrolyte; and carrying out battery assembly by taking the electrostatic spinning diaphragm as a battery diaphragm and an ionic solution as an electrolyte, enabling the ionic solution to completely infiltrate the electrostatic spinning diaphragm, and initiating in-situ polymerization of a polymer monomer under a heating condition to form the in-situ polymerization gel solid electrolyte based on the electrostatic spinning diaphragm. The high ionic conductivity is provided through the inorganic ceramic electrolyte particles evenly distributed in the electrostatic spinning diaphragm, the gel solid electrolyte is formed through infiltration and in-situ polymerization of the ionic solution, and the mechanical performance of the solid electrolyte membrane and the contact performance of the solid electrolyte membrane and an electrode are further improved.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte preparation technology, and in particular to an in-situ polymerized gel solid electrolyte based on an electrospun membrane and its preparation method. Background Technology

[0002] In current rechargeable battery technology, the electrolyte plays a crucial role, conducting ions between the positive and negative electrodes to support the battery's charging and discharging process. However, existing rechargeable battery electrolyte technologies face several challenges. Most current rechargeable batteries use liquid electrolytes, but these electrolytes are flammable, volatile, and prone to leakage, affecting not only battery safety but also potential environmental pollution.

[0003] To overcome the safety issues associated with liquid electrolytes, researchers have begun exploring solid polymer electrolytes. Polymer electrolytes, composed of a polymer matrix and lithium salts, offer higher safety and longer cycle life.

[0004] Existing technology CN113571767 A discloses a gel polymer electrolyte membrane, which optimizes the membrane's porosity and mechanical properties through the introduction of a polybenzimidazole-based gel polymer electrolyte membrane. However, in practical applications, it still faces problems such as cumbersome molding processes and insufficient interface stability.

[0005] While solid-state polymer electrolytes offer advantages in safety, establishing a stable solid-electrolyte interface within secondary batteries remains a significant technical challenge. Furthermore, improving the ionic conductivity and mechanical properties of polymer electrolytes remains a key research objective. Although current technologies have made progress in the field of polymer electrolytes, significant limitations still exist, necessitating further improvements. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing an in-situ polymerized gel solid electrolyte based on an electrospun membrane and its preparation method. An electrospun membrane framework structure with uniformly distributed inorganic ceramic electrolyte particles is prepared using coaxial electrospinning technology. This structure provides high ionic conductivity and excellent wettability for the solution in which the solid electrolyte is formed through in-situ polymerization. The gel solid polymer electrolyte is then obtained through in-situ polymerization. The in-situ polymerized gel solid electrolyte based on an electrospun membrane prepared by this method optimizes interfacial contact, enhances lithium-ion transport, and improves the electrochemical stability of lithium batteries.

[0007] To achieve the above objectives, the present invention provides a method for preparing an in-situ polymerized gel solid electrolyte based on an electrospun membrane, comprising:

[0008] An electrospun membrane and an ionic solution were prepared separately; the ionic solution included lithium salt, polymer monomer, and initiator; the electrospun membrane contained an inorganic ceramic solid electrolyte.

[0009] Using the electrospun separator as the battery separator and the ionic solution as the electrolyte, the battery is assembled so that the ionic solution completely wets the electrospun separator, and the polymer monomers are initiated to polymerize in situ under heating conditions to form an in situ polymerized gel solid electrolyte based on the electrospun membrane.

[0010] The preparation of the electrospun diaphragm includes:

[0011] The first polymer is added to the first organic solvent and stirred until homogeneous to obtain the first solution;

[0012] A nano-sized inorganic ceramic solid electrolyte is added to a second organic solvent and subjected to ultrasonic treatment to obtain a second solution. A second polymer is then added to the second solution and stirred until homogeneous to obtain a third solution.

[0013] The first and third solutions are transferred to an electrospinning apparatus for electrospinning to obtain an electrospinned membrane.

[0014] The electrospun membrane is dried and cut into pieces to obtain an electrospun diaphragm.

[0015] Preferably, the first polymer comprises one or more of PVDF, PEO, and PAN;

[0016] The first organic solvent includes: DMF and / or acetone;

[0017] The solid mass concentration in the first solution is 8%-20%;

[0018] The inorganic ceramic solid electrolyte includes one or more of LATP, LLTO, and LLZO.

[0019] The second organic solvent includes: DMF and / or acetone;

[0020] The solid mass concentration in the second solution is 8%-20%;

[0021] The second polymer includes one or more of PVDF, PEO, and PAN;

[0022] The second polymer has a solid mass concentration of 5%-15% in the third solution;

[0023] The ultrasonic treatment time is 30-60 minutes;

[0024] The stirring process specifically involves stirring at room temperature for 3-12 hours.

[0025] The drying process specifically involves drying in an oven at 50℃-80℃ for 6-12 hours.

[0026] More preferably, the solid mass concentration in the first solution is 10%;

[0027] The solid mass concentration in the second solution is 10%;

[0028] The second polymer has a solids mass concentration of 10% in the third solution.

[0029] Preferably, the preparation of the ionic solution specifically includes:

[0030] PEGDA, BA and lithium salt are mixed in a mass ratio of [4-6]:[2-3]:[2-3]. The mixture is heated and stirred at 30-50℃ for 30-60 minutes. After stirring until homogeneous, 0.2wt%-1wt% of initiator AlBN is added and stirring is continued for 30-60 minutes to obtain the first mixture.

[0031] SN, FEC and lithium salt are mixed in a mass ratio of [5-8]:[0.5-1]:[2-3], and heated and stirred at 30-50℃ for 30-60 minutes to obtain a second mixture;

[0032] The first mixture and the second mixture are mixed and heated and stirred at 30-50°C for 30-60 minutes to obtain the ionic solution.

[0033] Preferably, the lithium salt includes one or more of LiTFSI, LiPF6, LiDFOB, LiFSI, and LiBOB.

[0034] More preferably, the mass ratio of PEGDA, BA, and lithium salt is 2.5:1:1;

[0035] The amount of AI BN added is 0.3 wt%.

[0036] The mass ratio of SN, FEC and lithium salt is 5:0.5:2.

[0037] Preferably, the parameters of the electrospinning include: needle diameter 0.5 mm, spinning speed 1 ml / h, distance from needle to collecting plate 15 cm, humidity 25 RT%, temperature 25 °C, and voltage 10 kV.

[0038] Secondly, embodiments of the present invention provide an in-situ polymerized gel solid electrolyte based on an electrospinning membrane prepared by the preparation method described in the first aspect above.

[0039] Preferably, the in-situ polymerized gel solid electrolyte based on electrospinning membrane comprises: an electrospinning membrane framework structure with inorganic ceramic electrolyte particles uniformly distributed inside, and a gel solid polymer electrolyte polymerized in situ on the electrospinning membrane framework structure.

[0040] Thirdly, embodiments of the present invention provide a secondary battery, the secondary battery comprising the in-situ polymerized gel solid electrolyte based on electrospinning membrane described in the second aspect above.

[0041] The present invention provides a method for preparing an in-situ polymerized gel solid electrolyte based on an electrospun membrane. This method employs coaxial electrospinning technology to prepare an electrospun membrane framework structure with uniformly distributed inorganic ceramic electrolyte particles and good wetting properties. In-situ polymerization is then carried out by impregnating the electrospun membrane framework structure with an ionic solution, forming an in-situ polymerized gel solid electrolyte on the electrospun membrane framework structure. This method provides higher ionic conductivity through the introduction of inorganic ceramic electrolyte particles into the framework structure, and the gel solid polymer electrolyte formed by in-situ polymerization further improves mechanical properties and interfacial contact performance with the electrode. The preparation method of the present invention optimizes interfacial contact, enhances lithium-ion transport performance, and improves the electrochemical stability of lithium batteries. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the coaxial electrospinning equipment and process principle provided in an embodiment of the present invention. Detailed Implementation

[0043] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0044] This invention provides an in-situ polymerized gel solid electrolyte based on an electrospun membrane and its preparation method. The preparation method is described first.

[0045] The present invention proposes a method for preparing an in-situ polymerized gel solid electrolyte based on an electrospun membrane. First, an electrospun membrane and an ionic solution are prepared separately. Then, the electrospun membrane is used as the battery separator, and the ionic solution is used as the electrolyte. The battery is assembled so that the ionic solution completely wets the electrospun membrane, and the polymer monomers in the ionic solution are initiated to polymerize in situ under heating conditions to form an in-situ polymerized gel solid electrolyte based on an electrospun membrane.

[0046] The ionic solution includes lithium salt, polymer monomer and initiator; the electrospinning diaphragm contains inorganic ceramic solid electrolyte.

[0047] The above-mentioned electrospun diaphragm can be passed through Figure 1The coaxial electrospinning equipment and process principle shown are used for preparation, and the specific preparation steps include:

[0048] Step 110: Add the first polymer to the first organic solvent and stir until homogeneous to obtain the first solution;

[0049] The first polymer includes one or more of polyvinylidene fluoride (PVDF), polyethylene oxide (PEO), and polyacrylonitrile (PAN); the first organic solvent includes N,N-dimethylformamide (DMF) and / or acetone; and the solid mass concentration in the first solution is 8%-20%, preferably 10%.

[0050] The stirring process involves stirring at room temperature for 3-12 hours.

[0051] Step 120: Add the nano-sized inorganic ceramic solid electrolyte to the second organic solvent and sonicate it to obtain the second solution. Then add the second polymer to the second solution and stir until homogeneous to obtain the third solution.

[0052] Among them, inorganic ceramic solid electrolytes include one or more of lithium aluminum titanium phosphate (LATP), lithium lanthanum titanium oxide (LLTO), and lithium lanthanum zirconium oxide (LLZO).

[0053] The second organic solvent includes DMF and / or acetone; the solid mass concentration in the second solution is 8%-20%; preferably 10%.

[0054] The ultrasonic treatment time is 30-60 minutes.

[0055] The second polymer includes one or more of PVDF, PEO, and PAN; the solid mass concentration of the second polymer in the third solution is 5%-15%, preferably 10%.

[0056] The stirring process involves stirring at room temperature for 3-12 hours.

[0057] Step 130: Transfer the first solution and the third solution to an electrospinning apparatus for electrospinning to obtain an electrospinned membrane;

[0058] The first solution and the third solution pass through Figure 1The two syringes shown enable the transfer. The prepared first and third solutions are placed into the two syringes respectively, and the solutions are simultaneously injected through coaxial needles. A high voltage is applied by a high-voltage power supply; the electrostatic force generated by the high voltage stretches the solution, forming a jet stream, which is then stretched into nanoscale fibers. The charged fibers are ejected from the coaxial needles under the influence of electrostatic force and attracted to a grounded collector under the influence of an electric field. The collector can specifically be a rotating cylinder used to uniformly collect the fibers. A fiber membrane, i.e., an electrospun membrane, is deposited on the collector from the coaxial needles.

[0059] In a preferred example, the electrospinning parameters include: needle diameter 0.5 mm, spinning speed 1 ml / h, distance from needle to collecting plate 15 cm, humidity 25 RT%, temperature 25 °C, and voltage 10 kV.

[0060] Step 140: Dry and cut the electrospun membrane to obtain an electrospun diaphragm.

[0061] Specifically, drying involves drying in an oven at 50℃-80℃ for 6-12 hours.

[0062] The electrospun membrane prepared above serves as the electrolyte substrate, providing mechanical support and ion channels. During coaxial electrospinning, inorganic ceramic solid electrolyte powder is incorporated into the fibers and uniformly distributed. The electrospun membrane prepared by coaxial electrospinning technology has high porosity, which is beneficial for electrolyte wetting and lithium ion transport.

[0063] The specific preparation steps of the above ionic solution include:

[0064] Step 210: Ethylene glycol dimethacrylate (PEGDA), butyl acrylate (BA) and lithium salt are mixed in a mass ratio of [4-6]:[2-3]:[2-3]. The mixture is heated and stirred at 30-50°C for 30-60 minutes. After stirring evenly, 0.2wt%-1wt% of the initiator azobisisobutyronitrile (AIBN) is added, and stirring is continued for 30-60 minutes to obtain the first mixture.

[0065] The preferred lithium salt is LiTFS I, and the preferred mass ratio of PEGDA, BA and LiTFS I is 2.5:1:1.

[0066] PEGDA is a bifunctional monomer that can form a cross-linked polymer network under the action of an initiator. The polymer network formed by PEGDA can provide the electrolyte with mechanical strength and stability. BA, on the other hand, is a flexible monomer that participates in the polymerization reaction and can adjust the flexibility and elasticity of the polymer, so that the electrolyte has sufficient mechanical strength while also possessing better flexibility and ionic conductivity.

[0067] The preferred amount of AlBN added is 0.3 wt%. The role of adding the initiator AlBN is to generate free radicals by decomposing AlBN under heating conditions, which initiates the polymerization reaction, causing the polymer monomers to polymerize and form the desired polymer network structure.

[0068] Step 220: Succinate (SN), fluoroethylene carbonate (FEC) and lithium salt are mixed in a mass ratio of [5-8]:[0.5-1]:[2-3], and heated and stirred at 30-50°C for 30-60 minutes to obtain a second mixture;

[0069] The preferred lithium salt is LiTFS I, and the preferred mass ratio of SN, FEC and LiTFS I is 5:0.5:2.

[0070] SN, as an organic solvent, can dissolve lithium salts and help form a homogeneous mixture.

[0071] As an electrolyte additive, FEC can help form a stable solid electrolyte interphase (SEI) layer, thereby enhancing the cycle life and electrochemical stability of the battery.

[0072] Step 230: Mix the first mixture and the second mixture, and heat and stir at 30-50℃ for 30-60 minutes to obtain an ionic solution.

[0073] The lithium salts in steps 210 and 220 may include one or more of the following: lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium difluorooxalate borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium dioxalate borate (LiBOB). The lithium salts added in the two steps may be the same or different.

[0074] After obtaining the electrospun separator and the ionic solution, the electrospun separator is used as the battery separator and the ionic solution is used as the electrolyte to assemble the battery. The ionic solution completely wets the electrospun separator, and then it can be heated on a heating stage at 50-70℃ for 3-12 hours to initiate the in-situ polymerization of polymer monomers in the ionic solution, forming an in-situ polymerized gel solid electrolyte based on the electrospun membrane.

[0075] The in-situ polymerized gel solid electrolyte based on electrospun membrane prepared by the above method has an electrospun membrane skeleton structure with inorganic ceramic electrolyte particles uniformly distributed inside, and is a gel solid polymer electrolyte polymerized in situ on the electrospun membrane skeleton structure.

[0076] The present invention provides a method for preparing an in-situ polymerized gel solid electrolyte based on an electrospun membrane. This method employs coaxial electrospinning technology to prepare an electrospun membrane framework structure with uniformly distributed inorganic ceramic electrolyte particles and good wetting properties. In-situ polymerization is then carried out by impregnating the electrospun membrane framework structure with an ionic solution, forming an in-situ polymerized gel solid electrolyte on the electrospun membrane framework structure. This method provides higher ionic conductivity through the introduction of inorganic ceramic electrolyte particles into the framework structure, and the gel solid polymer electrolyte formed by in-situ polymerization further improves mechanical properties and interfacial contact performance with the electrode. The preparation method of the present invention optimizes interfacial contact, enhances lithium-ion transport performance, and improves the electrochemical stability of lithium batteries.

[0077] The in-situ polymerized gel solid electrolyte based on electrospun membrane prepared by this method exhibits high ionic conductivity and a larger electrochemical window, while also showing some improvement in mechanical properties. Furthermore, the reduced use of organic solvents during the preparation process enhances safety.

[0078] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0079] Example 1

[0080] This embodiment provides the preparation process and performance testing of in-situ polymerized gel solid electrolyte based on electrospun membrane.

[0081] The first step is to add 1g of PVDF to 10ml of DMF organic solvent, resulting in a solid mass concentration of 10%. Stir at room temperature for 6 hours to form a homogeneous solution, which is named solution A, for electrospinning.

[0082] The second step involves adding 1g of 200nm solid electrolyte powder LATP to 10ml of DMF organic solvent and sonicating for 30 minutes. Then, 1g of polymer PVDF is added, and the mixture is stirred at room temperature for 6 hours to form a homogeneous solution, named Solution B, for electrospinning.

[0083] The third step involves placing the prepared solutions A and B into syringes 1 and 2 respectively, and then transferring them to an electrospinning machine for electrospinning. The main parameters are: needle diameter 0.5 mm, spinning speed 1 ml / h, distance from needle to collecting plate 15 cm, humidity 25 RT%, temperature 25℃, and voltage 10 kV.

[0084] The fourth step is to place the electrospun film obtained by electrospinning into an oven at 80°C and dry it for 12 hours. Then, cut it into round pieces with a diameter of 17 mm and put them into a glove box for later use.

[0085] The following operations will all be performed inside the glove box.

[0086] Fifth step: Heat and stir 500mg of PEGDA, 200mg of BA and 200mg of LiTFSI at 50℃ for 60 minutes. After stirring evenly, add 3mg of initiator AI BN and continue stirring for 60 minutes to obtain solution C.

[0087] Step 6: Heat and stir 500 mg of SN, 50 mg of FEC and 200 mg of LiTFSI at 30 °C for 60 minutes to obtain solution D.

[0088] Step 7: Mix solution C and solution D, heat and stir at 30°C for 60 minutes until homogeneous to obtain an ionic solution.

[0089] The eighth step involves using the cut electrospun membrane as a separator and the prepared ionic solution as an electrolyte to assemble a button cell. During the assembly process, the ionic solution completely wets the electrospun membrane.

[0090] The ninth step involves heating the prepared button cell on a heating stage at 60°C for 3 hours to perform in-situ polymerization, thereby forming an in-situ polymerized gel solid electrolyte based on an electrospun membrane inside the cell.

[0091] It should be noted that the specific battery assemblies used for ionic conductivity testing and electrochemical window testing are different:

[0092] The conductivity test was performed using two stainless steel (SS) inert electrodes assembled into a battery.

[0093] The electrochemical window test used lithium metal sheets as the reference electrode and counter electrode, and stainless steel sheets (SS) as the working electrode to assemble a lithium / stainless steel (Li|SS) battery.

[0094] The obtained button batteries were subjected to ionic conductivity and electrochemical window tests, and the mechanical strength of the in-situ polymerized gel solid electrolyte after disassembly was tested.

[0095] The test methods are as follows:

[0096] Ionic conductivity testing: Electrochemical impedance spectroscopy (EIS) was performed on an electrochemical workstation. To ensure accuracy, the test battery was placed in a temperature-controlled chamber. In the EIS test, the frequency range was set from 0.01 Hz to 1 MHz, and the amplitude voltage was set to 10 mV to accurately measure the electrolyte resistance. Then, the ionic conductivity of the electrolyte was calculated using a formula based on the Nyquist impedance spectrum analysis. The formula used is as follows: In the determination of ionic conductivity, d in the formula represents the thickness of the electrolyte, R is the volume resistance of the electrolyte read from the Nyquist impedance diagram of EIS, and S represents the effective contact area between the electrolyte and the stainless steel inert electrode. To ensure the accuracy of the measurement, when testing the ionic conductivity at different temperatures, the constant temperature chamber needs to be set to the target temperature and maintained for half an hour to allow the test battery to reach thermal equilibrium. This step ensures the stability of the test environment, thereby allowing for accurate measurement of the ionic conductivity of the electrolyte at various temperatures.

[0097] Electrochemical window testing: Linear sweep voltammetry (LSV) was performed on the assembled test cells in a constant temperature chamber at room temperature. The scan rate was set to 1 mV / s, scanning from the open-circuit voltage to 5 V. To further evaluate the electrochemical performance of the electrolyte, cyclic voltammetry (CV) was performed in the same cell configuration over a potential range of -0.5 V to 2.5 V, also at a scan rate of 1 mV / s. These tests helped determine the stability and electrochemical behavior of the electrolyte at different potentials, thereby assessing its usability in battery applications.

[0098] Mechanical strength testing: The test was conducted using a universal tensile testing machine. The in-situ polymerized gel solid electrolyte based on the electrospun membrane was cut into rectangular electrolyte sheets of 5cm × 1cm. The thickness of the electrolyte membrane was then measured using vernier calipers. The cut electrolyte sheets were clamped on the tensile testing machine, and the stress strength and elastic modulus were tested by tensile testing.

[0099] The test results are recorded in Table 1.

[0100] Example 2

[0101] The difference between this embodiment and Embodiment 1 is that the second step is different, while the remaining steps are the same.

[0102] The solid electrolyte powder LATP added in the second step of this embodiment has a size of 150 nm.

[0103] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0104] Example 3

[0105] The difference between this embodiment and Embodiment 1 is that the second step is different, while the remaining steps are the same.

[0106] The solid electrolyte powder LATP added in the second step of this embodiment has a size of 100 nm.

[0107] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0108] Example 4

[0109] The difference between this embodiment and Embodiment 1 is that the second step is different, while the remaining steps are the same.

[0110] The solid electrolyte powder LATP added in the second step of this embodiment has a size of 50 nm.

[0111] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0112] Example 5

[0113] The difference between this embodiment and Embodiment 1 is that the second and third steps are different, while the remaining steps are the same.

[0114] The solid electrolyte powder LATP added in the second step of this embodiment has a size of 50 nm.

[0115] In the third step of this embodiment, the voltage for electrospinning is 15KV.

[0116] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0117] Example 6

[0118] The difference between this embodiment and Embodiment 1 is that the second and third steps are different, while the remaining steps are the same.

[0119] The solid electrolyte powder LATP added in the second step of this embodiment has a size of 50 nm.

[0120] In the third step of this embodiment, the voltage for electrospinning is 20KV.

[0121] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0122] Example 7

[0123] The difference between this embodiment and Embodiment 1 lies in the second, third, and ninth steps; the remaining steps are the same.

[0124] The solid electrolyte powder LATP added in the second step of this embodiment has a size of 50 nm.

[0125] In the third step of this embodiment, the voltage for electrospinning is 15KV.

[0126] In the ninth step of this embodiment, the heating time for in-situ polymerization is 6 hours.

[0127] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0128] Example 8

[0129] The difference between this embodiment and Embodiment 1 lies in the second, third, and ninth steps; the remaining steps are the same.

[0130] The solid electrolyte powder LATP added in the second step of this embodiment has a size of 50 nm.

[0131] In the third step of this embodiment, the voltage for electrospinning is 15KV.

[0132] In the ninth step of this embodiment, the heating time for in-situ polymerization is 9 hours.

[0133] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0134] Example 9

[0135] The difference between this embodiment and Embodiment 1 lies in the second, third, and ninth steps; the remaining steps are the same.

[0136] The solid electrolyte powder LATP added in the second step of this embodiment has a size of 50 nm.

[0137] In the third step of this embodiment, the voltage for electrospinning is 15KV.

[0138] In the ninth step of this embodiment, the heating time for in-situ polymerization is 12 hours.

[0139] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0140] Example 10

[0141] The difference between this embodiment and Embodiment 1 is that the first and second steps are different, while the remaining steps are the same.

[0142] In the first step of this embodiment, the mass of PVDF added is 1.5g, and the solid mass concentration is 15%.

[0143] In the second step of this embodiment, the mass of the solid electrolyte powder LATP added is 1.5g, and the solid mass concentration is 15%.

[0144] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0145] Example 11

[0146] The difference between this embodiment and Embodiment 1 is that the first and second steps are different, while the remaining steps are the same.

[0147] In the first step of this embodiment, the mass of PVDF added is 2g, and the solid mass concentration is 20%.

[0148] In the second step of this embodiment, the mass of the solid electrolyte powder LATP added is 2g, and the solid mass concentration is 20%.

[0149] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0150] To better demonstrate the technical advantages of this invention, the following three sets of comparative examples are used for comparison and verification.

[0151] Comparative Example 1

[0152] The difference between this embodiment and Embodiment 1 is that LATP material is not added in the second step, while the other steps are the same.

[0153] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0154] Comparative Example 2

[0155] The difference between this embodiment and Embodiment 1 is that LATP material is not added in the second step, and steps five and seven are omitted, with solution D used directly as the ionic solution; the remaining steps are the same.

[0156] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0157] Comparative Example 3

[0158] The difference between this comparative example and Example 1 is that the first and second steps are different, while the remaining steps are the same.

[0159] In the first step of this embodiment, the mass of PVDF added is 0.5g, and the solid mass concentration is 5%.

[0160] In the second step of this embodiment, the mass of the solid electrolyte powder LATP added is 0.5g, and the solid mass concentration is 5%.

[0161] The specific process of battery assembly and testing in this embodiment is the same as that in Embodiment 1, and the test results are recorded in Table 1.

[0162] Table 1 summarizes the test results of the above embodiments and comparative examples.

[0163] <![CDATA[Ionic conductivity (S cm -1 )]]> Electrochemical window (V) Stress intensity (MPa) Elastic modulus (%) Example 1 <![CDATA[2.11×10 -4 ]]> 4.51 7.4 275 Example 2 <![CDATA[2.62×10 -4 ]]> 4.62 7.33 267 Example 3 <![CDATA[3.21×10 -4 ]]> 4.71 7.65 276 Example 4 <![CDATA[3.24×10 -4 ]]> 4.82 7.83 297 Example 5 <![CDATA[3.14×10 -4 ]]> 4.79 7.76 283 Example 6 <![CDATA[3.03×10 -4 ]]> 4.57 7.66 278 Example 7 <![CDATA[3.11×10 -4 ]]> 4.67 8.21 310 Example 8 <![CDATA[3.31×10 -4 ]]> 4.82 8.45 332 Example 9 <![CDATA[2.98×10 -4 ]]> 4.71 7.78 318 Example 10 <![CDATA[2.75×10 -4 ]]> 4.42 6.12 190 Example 11 <![CDATA[2.82×10 -4 ]]> 4.67 7.31 253 Comparative Example 1 <![CDATA[0.12×10 -4 ]]> 3.9 7.12 256 Comparative Example 2 <![CDATA[0.71×10 -4 ]]> 4.01 4.41 102 Comparative Example 3 <![CDATA[1.01×10 -4 ]]> 4.13 5.12 140

[0164] Table 1

[0165] As can be seen from the data in Table 1, the ionic conductivity of Examples 1-11 is higher than that of Comparative Examples 1-3, and the electrochemical window of Examples 1-11 is also significantly higher than that of Comparative Examples 1-3. The stress intensity and elastic modulus of Examples 1-11 are also significantly improved compared to Comparative Examples 1-3. Comparative Example 1 is an electrolyte without the presence of electrodeless ceramic solid electrolyte material, and its electrochemical performance is poor. Comparative Example 2 is a product lacking solution C and therefore not subjected to in-situ polymerization; the mechanical strength of the prepared electrolyte membrane is significantly lower than that of the examples. The electrospinning precursor solution of Comparative Example 3 does not meet the solid mass concentration requirements, and the electrochemical performance and mechanical strength of the prepared electrolyte are not significantly improved.

[0166] The above data demonstrates that the gel solid electrolyte prepared by combining coaxial electrospinning and in-situ polymerization techniques exhibits significantly improved electrochemical performance and mechanical strength, with an ionic conductivity > 10. -4 S cm -1 The electrochemical window is >4.5V, and the stress intensity is >5MPa. The preparation method of this invention optimizes interfacial contact, enhances lithium-ion transport, and improves the electrochemical stability of lithium batteries.

[0167] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an in-situ polymerized gel solid electrolyte based on an electrospun membrane, characterized in that, The preparation method includes: An electrospun membrane and an ionic solution were prepared separately; the ionic solution included lithium salt, polymer monomer, and initiator; the electrospun membrane contained an inorganic ceramic solid electrolyte. Using the electrospun separator as the battery separator and the ionic solution as the electrolyte, the battery is assembled so that the ionic solution completely wets the electrospun separator, and the polymer monomers are initiated to polymerize in situ under heating conditions to form an in situ polymerized gel solid electrolyte based on the electrospun membrane. The preparation of the electrospun diaphragm includes: The first polymer is added to the first organic solvent and stirred until homogeneous to obtain the first solution; A nano-sized inorganic ceramic solid electrolyte is added to a second organic solvent and subjected to ultrasonic treatment to obtain a second solution. A second polymer is then added to the second solution and stirred until homogeneous to obtain a third solution. The first and third solutions are transferred to an electrospinning apparatus for electrospinning to obtain an electrospinned membrane. The electrospun membrane is dried and cut into pieces to obtain an electrospun diaphragm.

2. The preparation method according to claim 1, characterized in that, The first polymer includes one or more of the following: polyvinylidene fluoride (PVDF), polyethylene oxide (PEO), and polyacrylonitrile (PAN); The first organic solvent includes: N,N-dimethylformamide (DMF) and / or acetone; The solid mass concentration in the first solution is 8%-20%; The inorganic ceramic solid electrolyte includes one or more of lithium titanium aluminum phosphate (LATP), lithium lanthanum titanium oxide (LLTO), and lithium lanthanum zirconium oxide (LLZO). The second organic solvent includes: DMF and / or acetone; The solid mass concentration in the second solution is 8%-20%; The second polymer includes one or more of PVDF, PEO, and PAN; The second polymer has a solid mass concentration of 5%-15% in the third solution; The ultrasonic treatment time is 30-60 minutes; The stirring process specifically involves stirring at room temperature for 3-12 hours. The drying process specifically involves drying in an oven at 50℃-80℃ for 6-12 hours.

3. The preparation method according to claim 2, characterized in that, The solid mass concentration in the first solution is 10%; The solid mass concentration in the second solution is 10%; The second polymer has a solids mass concentration of 10% in the third solution.

4. The preparation method according to claim 1, characterized in that, The preparation of the ionic solution specifically includes: Ethylene glycol dimethacrylate (PEGDA), butyl acrylate (BA), and lithium salt were mixed in a mass ratio of [4-6]:[2-3]:[2-3]. The mixture was heated and stirred at 30-50°C for 30-60 minutes. After stirring until homogeneous, 0.2wt%-1wt% of the initiator azobisisobutyronitrile (AIBN) was added, and stirring was continued for another 30-60 minutes to obtain the first mixture. Succinate SN, fluoroethylene carbonate FEC and lithium salt are mixed in a mass ratio of [5-8]:[0.5-1]:[2-3] and heated and stirred at 30-50℃ for 30-60 minutes to obtain a second mixture; The first mixture and the second mixture are mixed and heated and stirred at 30-50°C for 30-60 minutes to obtain the ionic solution.

5. The preparation method according to claim 1 or 3, characterized in that, The lithium salt includes one or more of the following: lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium difluorooxalate borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium dioxalate borate (LiBOB).

6. The preparation method according to claim 3, characterized in that, The mass ratio of PEGDA, BA, and lithium salt is 2.5:1:1; The amount of AIBN added is 0.3 wt%. The mass ratio of SN, FEC and lithium salt is 5:0.5:

2.

7. The preparation method according to claim 1, characterized in that, The electrospinning parameters include: needle diameter 0.5 mm, spinning speed 1 ml / h, distance from needle to collecting plate 15 cm, humidity 25 RT%, temperature 25 °C, and voltage 10 KV.

8. An in-situ polymerized gel solid electrolyte based on an electrospinning membrane prepared by any of the preparation methods described in claims 1-7.

9. The in-situ polymerized gel solid electrolyte based on electrospun membrane according to claim 8, characterized in that, The in-situ polymerized gel solid electrolyte based on electrospun membrane comprises: an electrospun membrane skeleton structure with inorganic ceramic electrolyte particles uniformly distributed inside, and a gel solid polymer electrolyte polymerized in situ on the electrospun membrane skeleton structure.

10. A secondary battery, characterized in that, The secondary battery includes the in-situ polymerized gel solid electrolyte based on electrospun membrane as described in claim 8.

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