High-heat-resistance conductive polymer coating diaphragm as well as preparation method and application thereof
By modifying LLZTO and adding PPTA to form an interpenetrating network structure, the problems of insufficient heat resistance and conductivity of PEO composite LLZTO electrolyte membrane were solved, improving the high-temperature performance and mechanical strength of the battery and inhibiting lithium dendrite growth.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HEBEI GELLEC NEW ENERGY MATERIAL SCI&TECHNOLOY CO LTD
- Filing Date
- 2026-01-13
- Publication Date
- 2026-05-08
AI Technical Summary
Existing PEO composite LLZTO electrolyte membranes suffer from problems such as easy aggregation of LLZTO, phase separation, low ionic conductivity, poor high-temperature resistance, insufficient flexibility, and easy oxidation and decomposition, which limit battery performance.
By modifying LLZTO, introducing carboxyl groups and adding PPTA, an interpenetrating network structure is formed, which enhances the binding force and mechanical integrity with PEO, and optimizes the ion transport path and interfacial stability.
It improves the high-temperature stability, ionic conductivity and mechanical strength of the coated separator, inhibits lithium dendrite growth, and expands the application temperature range and pressure range of the battery.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery separator technology, specifically to a high heat-resistant and conductive polymer-coated separator, its preparation method, and its application. Background Technology
[0002] PEO-composite LLZTO (polyethylene oxide composite lithium lanthanum zirconium titanium oxide) electrolyte membranes are currently a hot research topic in solid-state batteries. By combining the flexibility of polymers with the high ionic conductivity of LLZTO, battery performance is significantly improved. The polymer-ceramic interface targeting effect suppresses LLZTO agglomeration and polymer crystallization, forming a uniform film structure with high mechanical strength. However, several key challenges remain: 1. LLZTO filler is prone to agglomeration, and LLZTO particles easily separate from the PEO matrix, resulting in discontinuous ion transport paths; 2. The PEO matrix has low ionic conductivity at room temperature (approximately 10). -8 ~10 -6 S·cm - ¹), and is not resistant to high temperatures, only working below 80℃; 3. The flexibility of the PEO matrix makes it difficult to suppress lithium dendrite growth, resulting in insufficient mechanical strength; 4. The PEO matrix is easily oxidized and decomposed at about 4V, limiting its high-voltage applications.
[0003] Therefore, there is an urgent need for a high-temperature resistant conductive polymer-coated diaphragm. Summary of the Invention
[0004] This invention proposes a high heat-resistant and conductive polymer-coated diaphragm, its preparation method, and its application, which solves the problems of insufficient high-temperature resistance and low ionic conductivity of polymer-coated diaphragms in related technologies.
[0005] The technical solution of the present invention is as follows: This invention proposes a high heat-resistant and conductive polymer-coated separator, comprising a base film and a coating applied to at least one side of the base film; the coating comprises a polymer and a modifier; the modifier comprises carboxylated LLZTO and PPTA.
[0006] As a further technical solution, the mass ratio of the polymer, carboxylated LLZTO, and PPTA is 1~3:1~3:0.5~1; The polymer includes at least one of PEO, PAA, PAN, PMMA, and PVDF-HFP.
[0007] As a further technical solution, the coating composition also includes lithium salt; the mass ratio of the polymer to the lithium salt is 1~3:0.1~0.3.
[0008] As a further technical solution, the lithium salt includes at least one of lithium bis(trifluorosulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.
[0009] As a further technical solution, the carboxylated LLZTO is prepared by reacting LLZTO powder with polycarboxylic acids under the action of a catalyst.
[0010] As a further technical solution, the polycarboxylic acid includes oxalic acid.
[0011] In this invention, LLZTO is modified by introducing polar carboxyl groups through oxalic acid, which induces amorphous regions in PEO, provides ion transport pathways, and optimizes interfacial stability. The carboxyl groups form a hydrogen bond network with the oxygen atoms of PEO, enhancing the filler-matrix interfacial bonding force; a rigid PPTA framework is introduced to form an interpenetrating network structure with PEO, enabling the coating to maintain mechanical integrity at high temperatures and preventing lithium dendrite penetration.
[0012] As a further technical solution, the catalyst includes a quaternary ammonium salt catalyst; the quaternary ammonium salt catalyst includes tetrabutylammonium bromide.
[0013] As a further technical solution, the preparation method of the carboxylated LLZTO includes the following steps: As a further technical solution, LLZTO powder is mixed with polycarboxylic acids, a catalyst is added, the mixture is reacted, centrifuged, washed, and dried to obtain carboxylated LLZTO powder.
[0014] As a further technical solution, the mass ratio of LLZTO powder to polycarboxylic acid is 1~2:2~4.
[0015] As a further technical solution, the reaction temperature is 60~80℃, the time is 30~60min, and the stirring speed is 300~500r / min.
[0016] As a further technical solution, the particle size of the LLZTO powder is 400~800nm.
[0017] As a further technical solution, the PPTA is prepared by polycondensation reaction of p-phenylenediamine and terephthaloyl chloride as raw materials.
[0018] As a further technical solution, the method for preparing PPTA includes the following steps: Under nitrogen protection, the co-solvent is dissolved in an organic solvent, p-phenylenediamine is added and mixed, terephthaloyl chloride is added, the reaction is carried out, imidazole is added, the reaction is carried out, and the mixture is filtered to obtain PPTA.
[0019] As a further technical solution, the co-solvent includes an alkaline earth metal chloride, which includes anhydrous lithium chloride.
[0020] This invention also proposes a method for preparing a high heat-resistant and conductive polymer-coated separator, comprising the following steps: The components of the coating are stirred at 40~60℃ and 300~500r / min for 2~4h to obtain a mixed slurry; The mixed slurry is coated on at least one side of the base film and dried at 70-80°C for 5-10 minutes to obtain a high heat-resistant and conductive polymer-coated separator.
[0021] The present invention also proposes the application of the high heat-resistant and conductive polymer-coated separator described herein or the high heat-resistant and conductive polymer-coated separator prepared by the aforementioned method in solid-state batteries.
[0022] The working principle and beneficial effects of this invention are as follows: In this invention, LLZTO is modified by introducing carboxyl groups to enhance its binding with PEO. The rigid framework of PPTA is used to form an interpenetrating network structure with PEO, thereby improving the following properties of the coated membrane: 1. Ion transport optimization: LLZTO carboxyl groups induce the formation of PEO amorphous regions, and PPTA rigid channels provide lithium-ion transport pathways; 2. Enhanced interface stability: The heat resistance of PPTA and the chemical inertness of LLZTO work together to delay the oxidative decomposition of PEO; 3. Mechanical property optimization: The modulus of PPTA and the flexibility of PEO form a gradient structure, which realizes uniform stress distribution, suppresses interface debonding, and maintains mechanical integrity at high temperature to avoid lithium dendrite penetration. Detailed Implementation
[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0024] In the following examples and comparative examples, the molecular weight of PEO is 100W; the thickness of the PE base film is 9.0μm and the porosity is 60%.
[0025] Example 1 The preparation method of carboxylated LLZTO includes the following steps: LLZTO powder with a particle size of 400 nm and oxalic acid are added to a reactor at a mass ratio of 1:1, and then tetrabutylammonium bromide (the mass of tetrabutylammonium bromide is 0.1% of the total mass of LLZTO powder and oxalic acid) is added to carry out the reaction. The reaction temperature is 60℃, the time is 30 min, the stirring speed is 300 r / min, the unreacted material is removed by centrifugation, the residue is removed by washing three times with deionized water, and the product is dried at 80℃ to obtain carboxylated LLZTO. The preparation method of PPTA includes the following steps: under nitrogen protection, 6.4g of anhydrous LiCl is dissolved in DMAC at 80℃, cooled to room temperature and 4.5g of PPDA is added. After dissolution, the mixture is cooled to 0℃ in an ice-water bath and 8.46g of TPC is added. After reacting for 20min, 4g of imidazole is added. After reacting for 40min, the mixture is filtered to obtain PPTA. A method for preparing a high heat-resistant and conductive polymer-coated separator includes the following steps: 3g of PEO was added to 96.7g of DMAC solvent containing 0.3g of LiTFSI, and stirred at 300r / min and 45℃ for 4h to obtain a PEO solution. The carboxylated LLZTO, PPTA and PEO solutions were stirred and mixed at 45℃ and 350r / min for 2h to obtain a mixed slurry, wherein the mass ratio of PEO, carboxylated LLZTO and PPTA was 3:3:1. The above-mentioned mixed slurry was coated onto a PE base film and dried in an oven at 70°C for 5 minutes to obtain a high heat-resistant and conductive polymer-coated separator.
[0026] Example 2 The preparation method of carboxylated LLZTO includes the following steps: LLZTO powder with a particle size of 400 nm and oxalic acid are added to a reactor at a mass ratio of 1:1.5, and then tetrabutylammonium bromide (the mass of tetrabutylammonium bromide is 0.15% of the total mass of LLZTO powder and oxalic acid) is added to carry out the reaction. The reaction temperature is 70℃, the time is 45 min, the stirring speed is 400 r / min, the unreacted material is removed by centrifugation, the residue is removed by washing three times with deionized water, and the product is dried at 80℃ to obtain carboxylated LLZTO. The preparation method of PPTA includes the following steps: under nitrogen protection, 6.4g of anhydrous LiCl is dissolved in DMAC at 80℃, cooled to room temperature and 4.5g of PPDA is added. After dissolution, the mixture is cooled to 0℃ in an ice-water bath and 8.46g of TPC is added. After reacting for 20min, 4g of imidazole is added. After reacting for 40min, the mixture is filtered to obtain PPTA. A method for preparing a high heat-resistant and conductive polymer-coated separator includes the following steps: 3g of PEO was added to 96.7g of DMAC solvent containing 0.3g of LiTFSI, and stirred at 300r / min and 45℃ for 4h to obtain a PEO solution. The carboxylated LLZTO, PPTA and PEO solutions were stirred and mixed at 45℃ and 350r / min for 2h to obtain a mixed slurry, wherein the mass ratio of PEO, carboxylated LLZTO and PPTA was 3:3:1. The above-mentioned mixed slurry was coated onto a PE base film and dried in an oven at 70°C for 5 minutes to obtain a high heat-resistant and conductive polymer-coated separator.
[0027] Example 3 The preparation method of carboxylated LLZTO includes the following steps: LLZTO powder with a particle size of 400 nm and oxalic acid are added to a reactor at a mass ratio of 1:2, and then tetrabutylammonium bromide (the mass of tetrabutylammonium bromide is 0.2% of the total mass of LLZTO powder and oxalic acid) is added to carry out the reaction. The reaction temperature is 80℃, the time is 60 min, the stirring speed is 500 r / min, the unreacted material is removed by centrifugation, the residue is removed by washing three times with deionized water, and the product is dried at 80℃ to obtain carboxylated LLZTO. The preparation method of PPTA includes the following steps: under nitrogen protection, 6.4g of anhydrous LiCl is dissolved in DMAC at 80℃, cooled to room temperature and 4.5g of PPDA is added. After dissolution, the mixture is cooled to 0℃ in an ice-water bath and 8.46g of TPC is added. After reacting for 20min, 4g of imidazole is added. After reacting for 40min, the mixture is filtered to obtain PPTA. A method for preparing a high heat-resistant and conductive polymer-coated separator includes the following steps: 3g of PEO was added to 96.7g of DMAC solvent containing 0.3g of LiTFSI, and stirred at 300r / min and 45℃ for 4h to obtain a PEO solution. The carboxylated LLZTO, PPTA and PEO solutions were stirred and mixed at 45℃ and 350r / min for 2h to obtain a mixed slurry, wherein the mass ratio of PEO, carboxylated LLZTO and PPTA was 3:3:1. The above-mentioned mixed slurry was coated onto a PE base film and dried in an oven at 70°C for 5 minutes to obtain a high heat-resistant and conductive polymer-coated separator.
[0028] Example 4 The only difference between this embodiment and Embodiment 3 is that the mass ratio of PEO, carboxylated LLZTO, and PPTA is 1:1:0.5.
[0029] Example 5 The only difference between this embodiment and Embodiment 3 is that the mass ratio of PEO, carboxylated LLZTO, and PPTA is 0.5:0.5:0.3.
[0030] Example 6 The only difference between this embodiment and Embodiment 3 is that the mass ratio of PEO, carboxylated LLZTO, and PPTA is 4:4:3.
[0031] Comparative Example 1 The preparation method of PPTA includes the following steps: under nitrogen protection, 6.4g of anhydrous LiCl is dissolved in DMAC at 80℃, cooled to room temperature and 4.5g of PPDA is added. After dissolution, the mixture is cooled to 0℃ in an ice-water bath and 8.46g of TPC is added. After reacting for 20min, 4g of imidazole is added. After reacting for 40min, the mixture is filtered to obtain PPTA. A method for preparing a high heat-resistant and conductive polymer-coated separator includes the following steps: 3g of PEO was added to 96.7g of DMAC solvent containing 0.3g of LiTFSI, and stirred at 300r / min and 45℃ for 4h to obtain a PEO solution. LLZTO powder (particle size 400nm), PPTA and PEO solution were stirred and mixed at 45℃ and 350r / min for 2h to obtain a mixed slurry, wherein the mass ratio of PEO, LLZTO powder and PPTA was 3:3:1. The above-mentioned mixed slurry was coated onto a PE base film and dried in an oven at 70°C for 5 minutes to obtain a high heat-resistant and conductive polymer-coated separator.
[0032] Comparative Example 2 The preparation method of PPTA includes the following steps: under nitrogen protection, 6.4g of anhydrous LiCl is dissolved in DMAC at 80℃, cooled to room temperature and 4.5g of PPDA is added. After dissolution, the mixture is cooled to 0℃ in an ice-water bath and 8.46g of TPC is added. After reacting for 20min, 4g of imidazole is added. After reacting for 40min, the mixture is filtered to obtain PPTA. A method for preparing a high heat-resistant and conductive polymer-coated separator includes the following steps: 3g of PEO was added to 96.7g of DMAC solvent containing 0.3g of LiTFSI, and stirred at 300r / min and 45℃ for 4h to obtain a PEO solution. PPTA and PEO solutions were stirred and mixed at 45℃ and 350r / min for 2h to obtain a mixed slurry, wherein the mass ratio of PEO to PPTA was 3:1. The above-mentioned mixed slurry was coated onto a PE base film and dried in an oven at 70°C for 5 minutes to obtain a high heat-resistant and conductive polymer-coated separator.
[0033] Comparative Example 3 The preparation method of carboxylated LLZTO includes the following steps: LLZTO powder with a particle size of 400 nm and oxalic acid are added to a reactor at a mass ratio of 1:2, and then tetrabutylammonium bromide (the mass of tetrabutylammonium bromide is 0.2% of the total mass of LLZTO powder and oxalic acid) is added to carry out the reaction. The reaction temperature is 80℃, the time is 60 min, the stirring speed is 500 r / min, the unreacted material is removed by centrifugation, the residue is removed by washing three times with deionized water, and the product is dried at 80℃ to obtain carboxylated LLZTO. A method for preparing a high heat-resistant and conductive polymer-coated separator includes the following steps: 3g of PEO was added to 96.7g of DMAC solvent containing 0.3g of LiTFSI, and stirred at 300r / min and 45℃ for 4h to obtain a PEO solution. The carboxylated LLZTO and PEO solutions were stirred and mixed at 45℃ and 350r / min for 2h to obtain a mixed slurry, wherein the mass ratio of PEO to carboxylated LLZTO was 3:3. The above-mentioned mixed slurry was coated onto a PE base film and dried in an oven at 70°C for 5 minutes to obtain a high heat-resistant and conductive polymer-coated separator.
[0034] Thickness, air permeability, breakdown voltage, thermal shrinkage, ionic conductivity, and adhesion were tested on the high heat-resistant and conductive polymer-coated membranes prepared in the above embodiments and comparative examples. Thickness: Refer to standard GB / T 6672-2001, use CHY-HS thickness gauge to test the thickness, and take the average value of multiple measurements; Air permeability: The membrane is placed on an Asahi Seiko (Japan) air permeability meter and tested at 10 points evenly. The average value is taken to obtain the air permeability of the membrane. Breakdown voltage: The diaphragm is laid flat on the test conductive plate, and 50 breakdown points are tested for each diaphragm to obtain the average breakdown voltage; Heat shrinkage: The diaphragm was cut into 4×6cm pieces, and the heat resistance stability of the diaphragm was calculated by measuring the dimensional change of the diaphragm in an oven at 120℃ for 1h. Ionic conductivity: The membrane is immersed in the electrolyte, and the impedance of the 1st to 4th membrane layers is measured sequentially. The corresponding impedance is obtained by fitting, and finally the corresponding ionic conductivity is obtained by the thickness. Diaphragm adhesion force: Cut the diaphragm into a 25×60cm shape, use tape to stick the coated diaphragm to the coated membrane, and use a tensile testing machine to tear the tape and the coated diaphragm apart. The force required to tear the tape and the coated diaphragm apart is the diaphragm adhesion force. The results are shown in Table 1 below.
[0035] Table 1 Performance Test Results
[0036] Air permeability test data show that the introduction of LLZTO can effectively reduce the air permeability of the coated membrane; at the same time, the enhanced mechanical properties based on PPTA significantly improve the thermal shrinkage and adhesion properties of the coated membrane; through LLZTO modification and synergistic effect with PEO, the LLZTO carboxylated surface can improve the interfacial compatibility with the polymer matrix, reduce interfacial impedance, and the carboxyl groups form hydrogen bonds with PEO hydroxyl groups, promoting lithium ion transport at the interface and giving the coated membrane excellent ionic conductivity.
[0037] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A high heat-resistant and conductive polymer-coated separator, characterized in that, It includes a base film and a coating applied to at least one side of the base film; the coating comprises a polymer and a modifier; the modifier includes carboxylated LLZTO and PPTA.
2. The high heat-resistant and conductive polymer-coated separator according to claim 1, characterized in that, The mass ratio of the polymer, carboxylated LLZTO, and PPTA is 1~3:1~3:0.5~1; The polymer includes at least one of PEO, PAA, PAN, PMMA, and PVDF-HFP.
3. The high heat-resistant and conductive polymer-coated separator according to claim 1, characterized in that, The coating also includes lithium salts; the mass ratio of the polymer to the lithium salt is 1~3:0.1~0.
3.
4. The high heat-resistant and conductive polymer-coated separator according to claim 3, characterized in that, The lithium salt includes at least one of lithium bis(trifluorosulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.
5. The high heat-resistant and conductive polymer-coated separator according to claim 1, characterized in that, The carboxylated LLZTO is prepared by reacting LLZTO powder with polycarboxylic acids under the action of a catalyst.
6. The high heat-resistant and conductive polymer-coated separator according to claim 1, characterized in that, The particle size of the LLZTO powder is 400~800nm.
7. The high heat-resistant and conductive polymer-coated separator according to claim 1, characterized in that, The PPTA is prepared by polycondensation reaction of p-phenylenediamine and terephthaloyl chloride.
8. The high heat-resistant and conductive polymer-coated separator according to claim 7, characterized in that, The method for preparing the PPTA includes the following steps: Under nitrogen protection, the co-solvent is dissolved in an organic solvent, p-phenylenediamine is added and mixed, terephthaloyl chloride is added, the reaction is carried out, imidazole is added, the reaction is carried out, and the mixture is filtered to obtain PPTA.
9. A method for preparing a high heat-resistant and conductive polymer-coated separator, used to prepare the high heat-resistant and conductive polymer-coated separator according to any one of claims 1 to 8, characterized in that, Includes the following steps: The components of the coating are stirred at 40~60℃ and 300~500r / min for 2~4h to obtain a mixed slurry; The mixed slurry is coated on at least one side of the base film and dried at 70-80°C for 5-10 minutes to obtain a high heat-resistant and conductive polymer-coated separator.
10. The application of a high heat-resistant and conductive polymer-coated separator according to any one of claims 1 to 8 or a high heat-resistant and conductive polymer-coated separator prepared by the preparation method according to claim 9 in a solid-state battery.