CN-122025791-A - Preparation method of double lithium salt type gel polymer electrolyte membrane

Abstract

The invention discloses a preparation method of a double lithium salt type gel polymer electrolyte membrane, which comprises the following steps of A, preparing a neutral flexible conjugated microporous polymer f-n-CMP supporting membrane, and B, preparing the double lithium salt type gel polymer electrolyte membrane by ultraviolet curing through the f-n-CMP supporting membrane prepared in the step A. The invention utilizes the high mechanical strength of the f-n-CMP support film to make up for the short plates with insufficient mechanical properties of the gel electrolyte film, does not need to strengthen the strength by excessively constructing a cross-linked network, introducing hydrogen bonds and the like, avoids the problems of reduced fluidity of polymer chain segments and blocked ion transmission, combines the synergistic effect of double lithium salts to optimize the ion transmission efficiency and is matched with an integrated polymer network constructed by ultraviolet curing in-situ polymerization. The invention integrates the f-n-CMP supporting film, ultraviolet light curing in-situ polymerization and double lithium salt in a synergistic way, and constructs the GPE with high ionic conductivity, excellent interface stability and mechanical strength.

Inventors

• TIAN GUIYING
• MAO RUNYE
• YAN SHUXIAO
• WANG LIUXUE
• LI JIAYI
• LIU YUGU
• KANG NA
• TANG NA

Assignees

• 天津科技大学

Dates

Publication Date

20260512

Application Date

20260330

Claims (10)

1. 1. A method for preparing a double lithium salt type gel polymer electrolyte membrane, which is characterized by comprising the following steps: step A, preparing a neutral flexible conjugated microporous polymer f-n-CMP supporting film; And B, preparing a double lithium salt type gel polymer electrolyte membrane by ultraviolet curing by using the f-n-CMP support membrane prepared in the step A.
2. 2. The method of claim 1, wherein in step a, the method of preparing the f-n-CMP supporting film comprises the steps of: Step A1, preparing electrolyte, namely mixing a rigid monomer and a flexible monomer, adding a supporting electrolyte, dissolving in a mixed solvent, and carrying out ultrasonic dispersion and deoxidization treatment to obtain electrolyte polymerization solution; Step A2, electrochemical copolymerization, namely adding the electrolyte polymerization solution obtained in the step A1 into an electrochemical cell by adopting a three-electrode electrochemical system, and applying scanning voltage by a cyclic voltammetry to carry out electrochemical copolymerization, so that carbazole units of a rigid monomer and a flexible monomer are coupled through oxidation crosslinking, and are deposited on the surface of the pretreated working electrode in situ to form a continuous film, thereby obtaining the working electrode deposited with the film; And step A3, post-treatment, namely soaking, stripping and transferring the load treatment to the working electrode deposited with the film obtained in the step A2, and performing hydrophobic modification by plasma to obtain the f-n-CMP supporting film.
3. 3. The method of claim 2, wherein in step A1, the rigid monomer is 1,3, 5-tris (N-carbazolyl) benzene TCB and the flexible monomer is 9H-carbazole-9-ethyl methacrylate CbzC 2 -OH; In the step A1, the molar ratio of the rigid monomer to the flexible monomer is 1:0.5-1:2; In step A1, the supporting electrolyte is tetrabutylammonium hexafluorophosphate TBAPF 6 ; In the step A1, the dosage of the supporting electrolyte is 1.2-1.8 g/40 mL mixed solvent; in the step A1, the mixed solvent is mixed liquid consisting of halogenated alkane solvent and nitrile solvent; in the step A1, the volume ratio of the halogenated alkane solvent to the nitrile solvent is 1:1-3:1; in the step A1, the halogenated alkane solvent is selected from one of dichloromethane DCM and chloroform, and the nitrile solvent is selected from one of acetonitrile ACN and propionitrile; in the step A1, the ultrasonic dispersion time is 20-40 min; in the step A1, the argon purging time is 10-20 min, and the argon purging time is used for removing oxygen in a system.
4. 4. The method according to claim 2, wherein in step A2, the working electrode of the three-electrode electrochemical system is pretreated ITO coated glass; In the step A2, the size of the ITO coated glass is 2 multiplied by 2 to 5 multiplied by 5 cm 2 ; in the step A2, the ITO coated glass is pretreated by ultrasonic cleaning for 10-20 min sequentially through deionized water, acetone and corresponding halogenated alkane solvents, and drying with nitrogen; In the step A2, a reference electrode of the three-electrode electrochemical system is a non-aqueous Ag/Ag + electrode containing 0.005-0.015 mol/L AgNO 3 , and a counter electrode of the three-electrode electrochemical system is a carbon fiber plate of 3X 5-5X 7 cm 2 ; In the step A2, the scanning voltage applied by the cyclic voltammetry is-0.80V-1.10V (vs Ag/Ag + ), the scanning speed is 50-120 mV/s, and the cycle times are 3-10 times.
5. 5. The preparation method of the thin film-deposited ITO coated glass according to claim 2, wherein in the step A3, the soaking, stripping and transferring load treatment comprises the steps of immersing the thin film-deposited ITO coated glass obtained in the step A2 in the mixed solvent of the step A1 for 20-40 min to remove unreacted monomers and free electrolyte, wherein the thin film-deposited ITO coated glass obtained in the step A2 is used as a working electrode; then transferring into an isopropanol aqueous solution with the concentration of 40% -60% (v/v) for soaking for 8-20 min to promote the stripping of the film and the ITO substrate, transferring into deionized water to enable the film to completely separate from the ITO and float on the water surface, loading the film onto a porous support by adopting a surface tension assisted transfer method, and drying by nitrogen; In the step A3, the porous support is selected from one of polyacrylonitrile PAN, polyvinylidene fluoride PVDF and anodic aluminum oxide AAO, and a surface tension assisted transfer method is adopted to load the membrane on the porous support; in the step A3, the gas introduced by the hydrophobic modification of the plasmas is CF 4 or SF 6 ; In the step A3, the plasma power is 30-60W, and the treatment time is 5-15 s.
6. 6. The method according to claim 1, wherein in the step B, the method for producing the dilithium salt type gel polymer electrolyte membrane comprises the steps of: step B1, uniformly mixing polymer monomer polyethylene glycol diacrylate PEGDA and ethoxylated trimethylolpropane triacrylate ETPTA with a photoinitiator to obtain pre-polymerization slurry; step B2, mixing the pre-polymerized slurry with ionic liquid, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium tetrafluoroborate LiBF 4 and alkenyl ethylene carbonate VEC to obtain mixed slurry; And B3, coating the mixed slurry on an f-n-CMP support film, and carrying out photopolymerization on the mixture in the step B2 in the protective atmosphere of inert gas Ar 2 to obtain the double lithium salt type gel polymer electrolyte membrane.
7. 7. The method according to claim 6, wherein in the step B1, the polyethylene glycol diacrylate monomer is selected from one of PEGDA 200, PEGDA 400, PEGDA 600, PEGDA 800, PEGDA 1000, and PEGDA 2000; in the step B1, the uniform mixing is constant-temperature stirring, and the temperature is 20-40 ℃; In the step B2, the viscosity of the mixed slurry is 300-10000 cP; the photoinitiator in the step B1 is selected from hydrogen-abstraction type free radical or cleavage type free radical ultraviolet initiator, and comprises one of 2,4, 6-trimethyl benzoyl-diphenyl phosphine oxide TPO, 2,4, 6-trimethyl benzoyl ethyl phosphonate TPO-L, 2-isopropyl thioxanthone ITX, diphenyl ketone BP and Michler's ketone MB.
8. 8. The method according to claim 6, wherein the slurry in step B3 is applied to one side of the prepared f-n-CMP supporting film, the film thickness of the formed electrolyte film is 100um to 150um, the ultraviolet light curing wavelength is 395nm, and the curing energy is 100-10000 mJ/cm 2 .
9. 9. The preparation method of the double lithium salt gel polymer electrolyte according to claim 6, wherein the ultraviolet light curing preparation method comprises the following raw materials of 38-wt% of polymer monomer, 12.7-wt% of cross-linking agent, 2.5-wt% of photoinitiator, 8% of LiTFSI and LiBF 4 , 33.8% of ionic liquid and 5% of VEC; The mass ratio of LiTFSI to LiBF 4 is 1:1, 1:1.5 and 1:2 respectively.
10. 10. A dilithium salt type gel polymer electrolyte membrane obtained by the production method according to any one of claims 1 to 9.

Description

Preparation method of double lithium salt type gel polymer electrolyte membrane Technical Field The invention relates to the technical field of electrochemical energy storage, in particular to a preparation method of a double lithium salt type gel polymer electrolyte membrane. Background In the field of electrochemical energy storage, the performance shortboards of conventional electrolyte systems are central to industry development. Although the liquid electrolyte has excellent room temperature ion conductivity of 10 -3~10-2S·cm-1 and good electrode contact, the liquid electrolyte has the characteristics of inflammability and easy leakage, and the problem of easy induction of lithium dendrite growth in the charge and discharge process, seriously threatens the safety application of power batteries, large-scale energy storage batteries and other equipment, while the all-solid polymer electrolyte can fundamentally solve the potential safety hazard, but has the fatal defect that the room temperature ion conductivity is only 10 -8~10-5S·cm-1, so that the reversible capacity and the cycle performance of the battery are greatly reduced, and the practical application requirements are difficult to meet. Under the background, gel Polymer Electrolyte (GPE) is used as a semi-solid system with high ionic conductivity of liquid electrolyte and high safety of solid electrolyte, and becomes a key research direction for filling the technical gap. The gel polymer electrolyte mainly comprises a polymer matrix, electrolyte salt and a plasticizer, and forms a special system between liquid and solid states. The incorporation of electrolyte in the gel matrix significantly enhances ionic conductivity at ambient temperature and improves the stability of the electrolyte-electrode interface. The ionic conductivity of GPE at ambient temperature was 10 -4~10-3 S·cm-1, comparable to commercial liquid electrolytes. This high ionic conductivity, combined with the operational safety, mechanical flexibility and incombustibility of GPE, is considered to be an ideal electrolyte for Lithium Metal Batteries (LMB). Common polymer matrices for GPE include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), and poly oxide (PEO). In the preparation process of the conventional Gel Polymer Electrolyte (GPEs), core technical problems are concentrated on multiple dimensions such as performance balance, interface stability, structure regulation and control, large-scale preparation and the like, and the problems severely restrict the practical process of the gel polymer electrolyte in the field of batteries. The control of the performance balance is a primary difficult problem, and the most central is the contradiction between the ionic conductivity and the mechanical strength of the teeterboard. In order to improve the ionic conductivity, solvent molecules are usually introduced or the concentration of lithium salt is usually increased, but the structural integrity of a polymer matrix is damaged, the mechanical property is greatly weakened, the capability of inhibiting the growth of lithium dendrites is reduced, and when the mechanical strength is enhanced by constructing a cross-linking network, introducing hydrogen bonds and the like, the fluidity of a polymer chain segment is reduced, or the ionic transmission is hindered due to the combination of polar functional groups and lithium ions. At the same time, the problem of insufficient ion transport performance at room temperature is also prominent. Most lithium ion system gel polymer electrolytes can exhibit desirable ionic conductivity under the high temperature conditions commonly used in laboratories, but their ionic conductivity can drop significantly in the room temperature environments involved in practical applications. Taking a conventional polyethylene oxide (PEO) based gel polymer electrolyte as an example, lithium ion migration is dependent on the movement of the polymer segments and the formation of continuous ion transport channels in the crosslinked network. At room temperature, the mobility of PEO chain segments is reduced, so that an ion transmission channel is narrowed, the diffusion rate of solvated lithium ions is reduced, the final ion conductivity is generally lower than 10 -4 S/cm, and the requirement of a high-power lithium ion battery on the dynamic performance is difficult to meet. In addition to the performance balancing challenge, poor interfacial stability also severely affects the practicality of GPEs. In the face of high-voltage positive electrodes (more than or equal to 4.3V vs. Li +/Li) such as NCM811, the conventional gel polymer electrolyte is easy to be subjected to oxidative decomposition, so that the problem of easy failure of the positive electrode interface under high voltage is solved. And transition metal ions (such as Ni 3+/Ni4+) released by the positive electrode can