Composite electrolyte diaphragm and preparation method thereof

Abstract

The invention relates to the technical field of electrolyte diaphragm preparation, in particular to a composite electrolyte diaphragm and a preparation method thereof, and the composite electrolyte diaphragm comprises a polymer, a lithium salt, an oxide ceramic electrolyte, a graphene nanosheet and lithium fluoride. The preparation method comprises the following steps: putting the polymer, the lithium salt, the oxide ceramic electrolyte, the graphene nanosheet and the lithium fluoride into a container according to the mass percent to obtain a mixed raw material; carrying out molding treatment on the mixed raw material to obtain a diaphragm prototype; carrying out modification treatment on the diaphragm prototype to obtain a modified diaphragm prototype; and carrying out surface modification treatment on the modified diaphragm prototype to obtain the composite electrolyte diaphragm. Through innovative design of links such as raw material treatment, a forming process, a modification method and surface modification, the defects of an existing diaphragm in the aspects of performance and process are overcome, and the composite electrolyte diaphragm with high porosity and high ionic conductivity is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolyte membrane preparation, and in particular to a composite electrolyte membrane and a preparation method thereof. Background Art

[0002] As a core component of the battery, the performance of the composite electrolyte diaphragm directly determines the safety, charge and discharge efficiency, and service life of the battery. Currently, traditional composite electrolyte diaphragms have many disadvantages. In terms of porosity and ion transport, the pore structure of some diaphragms is unreasonable, with low porosity and uneven distribution, resulting in poor electrolyte wettability and blocked ion migration channels, which seriously restricts the high-rate charge and discharge performance of the battery and cannot meet the demand for fast battery charge and discharge in fields such as new energy vehicles. In terms of ionic conductivity, the existing diaphragms have insufficient ion conduction capacity at room temperature, especially at low temperature, which increases the internal resistance of the battery, aggravates energy loss, and reduces the battery's range and overall energy efficiency.

[0003] In terms of mechanical properties, the diaphragm containing ceramic particles is very brittle. During battery assembly and long-term use, it is easy to break due to external forces such as extrusion and vibration, causing internal short circuits in the battery and threatening battery safety. Although polymer-based diaphragms have good flexibility, their mechanical strength is poor and they are unable to withstand process operations such as stretching and winding in the battery manufacturing process. They are prone to breakage, affecting the battery production yield and reliability.

[0004] In terms of thermal stability, under high temperature environment, the polymer material in the diaphragm is prone to softening and deformation, resulting in loss of dimensional stability of the diaphragm, collapse of the pore structure, destruction of ion transmission channels, and even causing thermal runaway of the battery, resulting in serious accidents such as fire and explosion.

[0005] From a cost and manufacturing perspective, traditional composite electrolyte separators rely on complex processes and expensive raw materials. Processes like electrospinning and sol-gel require specialized equipment and rigorous process control. Furthermore, the high cost of raw materials like high-performance polymers and nano-ceramic powders significantly increases battery production costs, limiting their large-scale commercial application. Furthermore, the poor interfacial compatibility between the separator and the electrodes creates significant interfacial resistance, hindering the efficient transfer of lithium ions between the electrodes and the separator, reducing the battery's charge-discharge performance and cycling stability.

[0006] Therefore, it is necessary to design a new type of composite electrolyte membrane and its preparation method to solve the above technical problems, improve the comprehensive performance of the membrane, and promote the development of battery technology. Summary of the Invention

[0007] In view of this, the present invention provides a composite electrolyte membrane and a preparation method thereof, aiming to overcome the shortcomings of existing membranes in performance, cost and process through innovative designs of raw material processing, molding process, modification method and surface modification, and prepare a composite electrolyte membrane with high porosity, high ionic conductivity, excellent mechanical properties and thermal stability, and with controllable cost and simple preparation process.

[0008] In one aspect, the present invention provides a composite electrolyte membrane, comprising: a polymer, a lithium salt, an oxide ceramic electrolyte, graphene nanosheets, and lithium fluoride;

[0009] The polymer, lithium salt, oxide ceramic electrolyte, graphene nanosheets and lithium fluoride are composed of the following parts by weight:

[0010] 40-50 parts of polymer, 20-30 parts of lithium salt, 10-15 parts of oxide ceramic electrolyte, 5-10 parts of graphene nanosheets, and 5-10 parts of lithium fluoride;

[0011] The polymers include polyethylene oxide, polyacrylonitrile and polyvinylidene fluoride;

[0012] The lithium salts include inorganic lithium salts and organic lithium salts;

[0013] The oxide ceramic electrolyte is one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconate and tantalum-doped lithium lanthanum zirconate.

[0014] Furthermore, the inorganic lithium salt is selected from one of lithium perchlorate, lithium hexafluorophosphate and lithium tetrafluoroborate; the organic lithium salt is selected from two of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate; the mass percentage of the inorganic lithium salt in the lithium salt is 6%-12%, and the mass percentage of the organic lithium salt in the lithium salt is 12%-25%.

[0015] On the other hand, the present invention also provides a method for preparing a composite electrolyte membrane, comprising the following steps:

[0016] Putting the polymer, lithium salt, oxide ceramic electrolyte, graphene nanosheets and lithium fluoride into a container according to mass percentage, stirring and mixing to obtain a mixed raw material;

[0017] Performing a molding process on the mixed raw materials to obtain a diaphragm prototype;

[0018] performing a modification treatment on the diaphragm prototype to obtain a modified diaphragm prototype;

[0019] The modified membrane prototype is subjected to surface modification treatment to obtain the composite electrolyte membrane.

[0020] Furthermore, before stirring and mixing, the graphene nanosheets and the oxide ceramic electrolyte are respectively subjected to surface activation treatment; the surface activation treatment comprises: placing the graphene nanosheets in an organic solvent and placing the oxide ceramic electrolyte powder in a citric acid solution;

[0021] The organic solvent is selected from one or more of N-methylpyrrolidone, a silane coupling agent and γ-aminopropyltriethoxysilane.

[0022] Furthermore, the molding process is performed in a molding die, and the steps of the molding process include:

[0023] Pre-treating the mold before the molding process, wherein the mold pre-treatment includes cleaning the mold surface;

[0024] During the molding process, the molding pressure is 5-10Mpa, the heating rate of the molding mold is 4-6°C / minute, the molding temperature is raised to 175-200°C, and the molding temperature is maintained for 15-25 minutes.

[0025] Furthermore, the modification treatment is carried out in a modification device containing a modification gas, the volume fraction of the modification gas is 10%-20%, the modification treatment temperature is 110-140° C., the modification treatment pressure is 0.4-0.6 MPa, and the modification treatment time is 2-3 hours.

[0026] Furthermore, the surface modification treatment step includes: using a coating device to coat a solution containing a surface modifier on the surface of the modified membrane prototype; the surface modifier is a polymer containing bonding groups and functional groups; the concentration of the coating solution is 4-7 g / L, and the coating speed is 0.4-0.6 m / min.

[0027] Furthermore, the stirring and mixing process is: first low-speed stirring, then high-speed stirring; the low-speed stirring speed is 90-130 rpm, the low-speed stirring time is 10-15 minutes, and the high-speed stirring speed is 450-650 rpm, and the high-speed stirring time is 30-35 minutes.

[0028] Furthermore, the modified gas is one or more of ammonia, water vapor or carbon dioxide.

[0029] Furthermore, the surface modification treatment also includes a drying post-treatment, with a drying temperature of 75-90° C. and a drying time of 1-2 hours.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention overcomes the performance, cost, and process limitations of existing membranes through innovative design of raw material processing, molding, modification, and surface modification. This approach offers controllable costs and a simple preparation process. The resulting composite electrolyte membrane exhibits excellent overall performance, including high porosity, high ionic conductivity, superior mechanical properties, and thermal stability, promising market application prospects and high commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0033] Figure 1 A flow chart for preparing a composite electrolyte membrane provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0035] Traditional composite electrolyte membranes have numerous drawbacks. Some membranes have an illogical pore structure, low porosity, and uneven distribution, resulting in poor electrolyte wettability and an inability to meet the rapid charging and discharging demands of batteries in new energy vehicles and other applications. Existing membranes also have insufficient ion conductivity at room temperature, and especially at low temperatures. This increases the battery's internal resistance, exacerbating energy loss and reducing the battery's range and overall energy efficiency.

[0036] The diaphragm containing ceramic particles is very brittle. During battery assembly and long-term use, it is easy to break due to external forces such as extrusion and vibration, causing internal short circuits in the battery and threatening battery safety. Under high temperature conditions, the polymer material in the diaphragm is easy to soften and deform, resulting in loss of dimensional stability of the diaphragm, collapse of the pore structure, destruction of ion transmission channels, and even thermal runaway of the battery, causing serious accidents such as fire and explosion.

[0037] Traditional composite electrolyte separators rely on complex processes and expensive raw materials. Processes like electrospinning and sol-gel require specialized equipment and rigorous process control. Furthermore, the high cost of raw materials like high-performance polymers and nano-ceramic powders significantly increases battery production costs, limiting their large-scale commercial application. Furthermore, the poor interfacial compatibility between the separator and the electrodes creates significant interfacial resistance, hindering the efficient transfer of lithium ions between the electrodes and the separator, reducing the battery's charge-discharge performance and cycling stability.

[0038] Therefore, it is necessary to design a new type of composite electrolyte membrane and its preparation method to solve the above technical problems, improve the comprehensive performance of the membrane, and promote the development of battery technology.

[0039] The present invention provides a composite electrolyte membrane, which comprises: a polymer, a lithium salt, an oxide ceramic electrolyte, graphene nanosheets and lithium fluoride.

[0040] Specifically, the polymer, lithium salt, oxide ceramic electrolyte, graphene nanosheets and lithium fluoride are composed of the following parts by weight: 40-50 parts of polymer, 20-30 parts of lithium salt, 10-15 parts of oxide ceramic electrolyte, 5-10 parts of graphene nanosheets and 5-10 parts of lithium fluoride.

[0041] Specifically, the polymer includes polyethylene oxide, polyacrylonitrile and polyvinylidene fluoride; the lithium salt includes inorganic lithium salt and organic lithium salt; the oxide ceramic electrolyte is one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconate and tantalum-doped lithium lanthanum zirconate.

[0042] In some embodiments of the present application, the inorganic lithium salt is selected from one of lithium perchlorate, lithium hexafluorophosphate and lithium tetrafluoroborate; the organic lithium salt is selected from two of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate; the mass percentage of the inorganic lithium salt in the lithium salt is 6%-12%, and the mass percentage of the organic lithium salt in the lithium salt is 12%-25%.

[0043] It is understandable that a reasonable lithium salt ratio can optimize the ion conductivity of the diaphragm, balance the advantages of different lithium salts, and improve the charge and discharge efficiency of the battery under different working conditions.

[0044] It is understandable that polymers provide a basic film-forming framework and a certain degree of flexibility; oxide ceramic electrolytes improve the mechanical strength and thermal stability of the diaphragm, making up for the defect of traditional polymer diaphragms that are easily deformed at high temperatures; graphene nanosheets, with their high conductivity and excellent mechanical properties, construct efficient ion transport channels and enhance mechanical properties; lithium fluoride optimizes the surface properties of the diaphragm and improves the interface compatibility with the electrode, thereby significantly improving the overall performance of the diaphragm.

[0045] It can be seen that the composite electrolyte membrane overcomes the problems of poor mechanical strength and thermal stability of traditional polymer membranes by combining polymers with oxide ceramic electrolytes; the combination of graphene nanosheets and lithium salts optimizes the ion transport performance and improves the battery charge and discharge efficiency; the addition of lithium fluoride improves interface compatibility, reduces battery internal resistance, and enhances battery cycle stability and safety.

[0046] See Figure 1 As shown, an embodiment of the present invention provides a method for preparing a composite electrolyte membrane, comprising:

[0047] S1. Put the polymer, lithium salt, oxide ceramic electrolyte, graphene nanosheets and lithium fluoride into a container according to mass percentage, stir and mix, and obtain a mixed raw material.

[0048] S2. Forming the mixed raw materials to obtain a diaphragm prototype.

[0049] S3. Modifying the membrane prototype to obtain a modified membrane prototype.

[0050] S4. Performing surface modification treatment on the modified membrane prototype to obtain the composite electrolyte membrane.

[0051] It can be understood that stirring and mixing ensures the uniform dispersion of the raw materials, ensuring the consistency of the separator composition; molding treatment imparts the desired shape and preliminary microstructure to the separator; modification treatment improves the separator's ion conductivity and thermal stability; and surface modification treatment optimizes the interface between the separator and the electrode, reducing interfacial resistance. These steps are closely linked to ensure the preparation of a high-performance composite electrolyte separator.

[0052] As can be seen, compared to traditional preparation methods, this method, through the synergistic action of multiple steps, can precisely control the structure and properties of the separator. From raw material mixing to final modification, each step is optimized for the specific properties of the separator, resulting in a product with comprehensive performance far exceeding that of traditional separators, improving the overall performance and reliability of the battery.

[0053] See Figure 1 As shown, in some embodiments of the present application, the graphene nanosheets and the oxide ceramic electrolyte are respectively subjected to surface activation treatment before being stirred and mixed.

[0054] Specifically, the surface activation treatment includes placing graphene nanosheets in an organic solvent and placing oxide ceramic electrolyte powder in a citric acid solution.

[0055] Specifically, the organic solvent is selected from one or more of N-methylpyrrolidone, a silane coupling agent and γ-aminopropyltriethoxysilane.

[0056] It is understood that surface active treatment can improve the surface properties of graphene nanosheets and oxide ceramic electrolytes, enhance their dispersion in the mixed system and their compatibility with other raw materials, and prevent agglomeration. Good dispersion and compatibility help fully utilize the performance advantages of these two raw materials and ensure the uniformity and stability of the separator performance.

[0057] It is understood that after the surfactant treatment, the separator becomes more uniform in microstructure, avoiding performance defects caused by raw material agglomeration. This makes the separator's mechanical strength and ion conductivity more stable and excellent, significantly improving the performance consistency and reliability of the battery compared to the untreated case.

[0058] See Figure 1 As shown, in some embodiments of the present application, the molding process is performed in a molding mold.

[0059] Specifically, the molding process includes: pre-treating the mold before the molding process, and the mold pre-treatment includes cleaning the mold surface; during the molding process, the molding pressure is 5-10Mpa, the heating rate of the molding mold is 4-6°C / minute, the molding temperature is raised to 175-200°C, and the molding temperature is maintained for 15-25 minutes.

[0060] Specifically, the molding pressure is preferably 8 MPa, the heating rate of the molding die is preferably 5° C. / min, the molding temperature is preferably raised to 185° C., and the molding temperature holding time is preferably 20 minutes.

[0061] It's understandable that mold pretreatment ensures a clean mold surface and prevents impurities from contaminating the diaphragm. Precisely controlling the molding pressure, heating rate, temperature, and hold time can regulate the diaphragm's microstructure and pore morphology. Appropriate pressure and temperature conditions facilitate phase transformation of the raw materials, forming an ideal diaphragm structure and improving the membrane's porosity and mechanical strength.

[0062] As can be seen, the present invention, through precise molding process control, produces a separator with excellent pore structure and mechanical properties. High porosity facilitates electrolyte infiltration and ion migration, improving battery charge and discharge performance. Sufficient mechanical strength prevents the separator from breaking during battery assembly and use, improving battery production yield and safety. Compared to traditional molding processes, the separator significantly improves performance.

[0063] See Figure 1 As shown, in some embodiments of the present application, the modification process is performed in a modification device containing a modification gas.

[0064] Specifically, the volume fraction of the modified gas is 10%-20%, the modification treatment temperature is 110-140° C., the modification treatment pressure is 0.4-0.6 MPa, and the modification treatment time is 2-3 hours.

[0065] Specifically, the volume fraction of the reforming gas is preferably 15%, the reforming treatment temperature is preferably 130° C., the reforming treatment pressure is preferably 0.5 MPa, and the reforming treatment time is preferably 2.5 hours.

[0066] It is understood that under specific temperature, pressure, and gas conditions, the modified gas reacts chemically with the separator, forming a modified layer on the separator's surface and interior. This modified layer can alter the separator's chemical composition and structure, improving its ion conductivity and thermal stability, and enhancing the battery's adaptability in different environments.

[0067] See Figure 1 As shown, in some embodiments of the present application, the surface modification treatment step includes: using a coating device to coat a solution containing a surface modifier on the surface of the modified membrane prototype.

[0068] Specifically, the surface modifier is a polymer containing a bonding group and a functional group; the concentration of the coating solution is 4-7 g / L, and the coating speed is 0.4-0.6 m / min.

[0069] Specifically, the concentration of the coating solution is preferably 6 g / L, and the coating speed is preferably 0.5 m / min.

[0070] It is understood that the surface modifier solution forms a functional layer on the surface of the separator. The bonding groups can enhance the adhesion between the separator and the electrode, while the functional groups optimize the interface contact between the separator and the electrode, reducing the interface resistance, thereby improving the battery's charge and discharge efficiency and cycle stability. This in turn improves the battery's charge and discharge efficiency and extends its cycle life.

[0071] See Figure 1 As shown, in some embodiments of the present application, the stirring and mixing process is: first stirring at a low speed, and then stirring at a high speed.

[0072] Specifically, the low-speed stirring speed is 90-130 rpm, the low-speed stirring time is 10-15 minutes, the high-speed stirring speed is 450-650 rpm, and the high-speed stirring time is 30-35 minutes.

[0073] Specifically, the low-speed stirring speed is preferably 120 rpm, and the low-speed stirring time is preferably 12 minutes. The high-speed stirring speed is preferably 600 rpm, and the high-speed stirring time is preferably 33 minutes.

[0074] It can be understood that low-speed stirring allows the raw materials to be initially mixed, avoiding splashing or agglomeration of some raw materials due to high-speed stirring; high-speed stirring further allows the raw materials to be fully and evenly dispersed, ensuring the consistency of the mixed materials and providing a guarantee for subsequent molding and stable performance.

[0075] It can be seen that the staged stirring method can more effectively achieve uniform mixing of raw materials than a single stirring speed. This makes the prepared diaphragm have uniform composition and stable performance, avoids the performance differences of the diaphragm caused by uneven mixing, and improves the quality and reliability of the diaphragm product.

[0076] See Figure 1 As shown, in some embodiments of the present application, the modified gas is one or more of ammonia, water vapor or carbon dioxide.

[0077] See Figure 1 As shown, in some embodiments of the present application, the surface modification treatment further includes a drying post-treatment, the drying temperature is 75-90° C., and the drying time is 1-2 hours.

[0078] Specifically, the drying temperature is preferably 75-90° C., and the drying time is preferably 1-2 hours.

[0079] It is understood that the drying process can remove the solvent in the surface modifier solution, allowing the surface modifier to firmly adhere to the separator surface, forming a stable functional layer. This can continuously and effectively improve the interface performance between the separator and the electrode, thereby enhancing the stability and reliability of the battery.

[0080] As can be seen, the present invention overcomes the performance, cost, and process deficiencies of existing membranes through innovative design in raw material processing, molding, modification, and surface modification, resulting in cost-controllable and simple preparation. The resulting composite electrolyte membrane exhibits excellent overall performance, including high porosity, high ionic conductivity, excellent mechanical properties, and thermal stability, promising market application prospects and high commercial value.

[0081] Example 1

[0082] S1. Place 6 parts of graphene nanosheets in N-methylpyrrolidone and treat for 1 hour, and place 9 parts of oxide ceramic electrolyte powder in citric acid solution and treat for 1 hour, and then take out and dry.

[0083] S2. Place the treated graphene nanosheets and oxide ceramic electrolyte powder, 42 parts of polymer, 22 parts of lithium salt, and 11 parts of oxide ceramic electrolyte into a container, first stir at a low speed of 100 rpm for 12 minutes, and then stir at a high speed of 500 rpm for 32 minutes to obtain a mixed raw material.

[0084] S3. Wipe the surface of the molding mold with alcohol to clean it, put the mixed raw materials into the molding mold, and heat it to 180°C at a heating rate of 5°C / min under a pressure of 6 MPa. Keep it for 20 minutes and then demould it to obtain the diaphragm prototype.

[0085] S4. Place the diaphragm prototype into a modification device containing 12% ammonia, and treat it at 120° C. and 0.5 MPa for 2 hours to obtain a modified diaphragm prototype.

[0086] S5. Prepare a polymer solution containing bonding groups and functional groups with a concentration of 5 g / L, apply it on the surface of the modified membrane prototype using a coating device at a coating speed of 0.5 m / min, and then dry it at 80° C. for 1 hour to obtain a composite electrolyte membrane.

[0087] Example 2

[0088] S1. Place 8 parts of graphene nanosheets in N-methylpyrrolidone and treat for 1.2 hours, and place 7 parts of oxide ceramic electrolyte powder in citric acid solution and treat for 1.2 hours, and then take out and dry.

[0089] S2. Place the treated graphene nanosheets and oxide ceramic electrolyte powder, 48 parts of polymer, 28 parts of lithium salt, and 14 parts of oxide ceramic electrolyte into a container, first stir at a low speed of 120 rpm for 14 minutes, and then stir at a high speed of 600 rpm for 34 minutes to obtain a mixed raw material.

[0090] S3. Wipe the surface of the molding mold with alcohol to clean it, put the mixed raw materials into the molding mold, and heat it to 195°C at a heating rate of 6°C / min under a pressure of 8 MPa. After maintaining it for 23 minutes, demould it to obtain the diaphragm prototype.

[0091] S4. Place the diaphragm prototype into a modification device containing 12% ammonia, and treat it at 135° C. and 0.6 MPa for 2.5 hours to obtain a modified diaphragm prototype.

[0092] S5. Prepare a polymer solution containing bonding groups and functional groups with a concentration of 6 g / L, apply it on the surface of the modified membrane prototype using a coating device at a coating speed of 0.6 m / min, and then dry it at 85° C. for 1.5 hours to obtain a composite electrolyte membrane.

[0093] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or a combination of software and hardware embodiments. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0094] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0095] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A composite electrolyte membrane, characterized in that The raw materials of the composite electrolyte membrane include: polymer, lithium salt, oxide ceramic electrolyte, graphene nanosheets and lithium fluoride; The polymer, lithium salt, oxide ceramic electrolyte, graphene nanosheets and lithium fluoride are composed of the following parts by weight: 40-50 parts of polymer, 20-30 parts of lithium salt, 10-15 parts of oxide ceramic electrolyte, 5-10 parts of graphene nanosheets, and 5-10 parts of lithium fluoride; The polymers include polyethylene oxide, polyacrylonitrile and polyvinylidene fluoride; The lithium salts include inorganic lithium salts and organic lithium salts; The oxide ceramic electrolyte is one or more of lithium aluminum titanium phosphate, lithium lanthanum zirconate and tantalum-doped lithium lanthanum zirconate.

2. A composite electrolyte membrane according to claim 1, characterized in that: The inorganic lithium salt is selected from one of lithium perchlorate, lithium hexafluorophosphate and lithium tetrafluoroborate; the organic lithium salt is selected from two of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate; the mass percentage of the inorganic lithium salt in the lithium salt is 6%-12%, and the mass percentage of the organic lithium salt in the lithium salt is 12%-25%.

3. A method for preparing a composite electrolyte membrane according to any one of claims 1 to 2, characterized in that: The following steps are involved: Putting the polymer, lithium salt, oxide ceramic electrolyte, graphene nanosheets and lithium fluoride into a container according to mass percentage, stirring and mixing to obtain a mixed raw material; Performing a molding process on the mixed raw materials to obtain a diaphragm prototype; performing a modification treatment on the diaphragm prototype to obtain a modified diaphragm prototype; The modified membrane prototype is subjected to surface modification treatment to obtain the composite electrolyte membrane.

4. The method for preparing a composite electrolyte membrane according to claim 3, wherein: Before stirring and mixing, the graphene nanosheets and the oxide ceramic electrolyte are respectively subjected to surface activation treatment; the surface activation treatment comprises: placing the graphene nanosheets in an organic solvent and placing the oxide ceramic electrolyte powder in a citric acid solution; The organic solvent is selected from one or more of N-methylpyrrolidone, a silane coupling agent and γ-aminopropyltriethoxysilane.

5. The method for preparing a composite electrolyte membrane according to claim 3, characterized in that: The molding process is performed in a molding die, and the steps of the molding process include: Pre-treating the mold before the molding process, wherein the mold pre-treatment includes cleaning the mold surface; During the molding process, the molding pressure is 5-10Mpa, the heating rate of the molding mold is 4-6°C / minute, the molding temperature is raised to 175-200°C, and the molding temperature is maintained for 15-25 minutes.

6. The method for preparing a composite electrolyte membrane according to claim 3, characterized in that: The modification treatment is carried out in a modification device containing a modification gas, the volume fraction of the modification gas is 10%-20%, the modification treatment temperature is 110-140° C., the modification treatment pressure is 0.4-0.6 MPa, and the modification treatment time is 2-3 hours.

7. The method for preparing a composite electrolyte membrane according to claim 3, characterized in that: The surface modification treatment step includes: using a coating device to coat a solution containing a surface modifier on the surface of the modified membrane prototype; the surface modifier is a polymer containing bonding groups and functional groups; the concentration of the coating solution is 4-7g / L, and the coating speed is 0.4-0.6m / min.

8. The method for preparing a composite electrolyte membrane according to claim 3, characterized in that: The stirring and mixing process is: first low-speed stirring, then high-speed stirring; the low-speed stirring speed is 90-130 rpm, the low-speed stirring time is 10-15 minutes, and the high-speed stirring speed is 450-650 rpm, and the high-speed stirring time is 30-35 minutes.

9. The method for preparing a composite electrolyte membrane according to claim 6, characterized in that: The modified gas is one or more of ammonia, water vapor or carbon dioxide.

10. The method for preparing a composite electrolyte membrane according to claim 7, characterized in that: The surface modification treatment also includes a drying post-treatment, with the drying temperature being 75-90° C. and the drying time being 1-2 hours.

Images