Dielectric film with PI for solid-state battery

Abstract

The invention relates to a dielectric film with PI (polyimide) for a solid-state battery. The solid-state battery comprises a positive electrode, a negative electrode and a dielectric film located between the positive electrode and the negative electrode. The dielectric film is formed by combining PVDF (Polyvinylidene Fluoride), a plurality of LLZO (Lithium-Lanthanum-Zirconium-Oxide) particles, a polyimide (PI) modifier and LiTFSI (LiN (CF3SO2) 2, bis (trifluoromethanesulfonyl) lithium imide), and is characterized in that the dielectric film is prepared from PVDF (Polyvinylidene Fluoride), a plurality of LLZO particles, a polyimide (PI) modifier and LiTFSI (LiN (CF3SO2) 2, bis (trifluoromethanesulfonyl) lithium imide; wherein the polyimide (PI) modifier is a polymer material having good heat resistance, chemical resistance and electrical insulation; the polyimide (PI) modifier is mixed with the LLZO particles, so that the surface energy of the LLZO particles can be effectively reduced, and the surface stability of the LLZO particles can be improved.

Description

Technical Field

[0001] This invention relates to dielectric films for solid electrolytes, and more particularly to a dielectric film with PI for use in solid-state batteries. Background Technology

[0002] Traditionally, solid-state or solid-state batteries typically include a positive electrode, a negative electrode, and a dielectric film located between the positive and negative electrodes. The dielectric film is coated between the positive and negative electrodes to isolate them and allow lithium ions to pass through. The dielectric film generally comprises a PE (Polyethylene) layer or other dielectric material layer with a thickness between 5 and 10 micrometers.

[0003] In practical applications, solid-state batteries often use a mixed slurry layer containing LLZO as the dielectric material. LLZO is a solid electrolyte material with high ionic conductivity, good thermal stability, and chemical resistance. However, LLZO has a high surface energy and readily reacts with media such as air and water, forming an unstable interfacial layer that reduces the performance and stability of the solid electrolyte.

[0004] However, the traditional application of LLZO as an ion-conducting mixed slurry layer suffers from excessively high band density and poor stability, resulting in inadequate overall lithium-ion conductivity. Based on the inventors' extensive knowledge in the chemical industry, polyimide (PI) modifiers are polymer materials with excellent heat resistance, chemical resistance, and electrical insulation. Introducing polyimide (PI) modifiers into LLZO can effectively reduce its surface energy and improve its surface stability. Therefore, the inventors sought a novel technology to effectively incorporate polyimide (PI) modifiers into the LLZO mixed slurry layer, thereby improving the overall properties of the mixed slurry layer.

[0005] The synthesis of this polyimide (PI) modifier is briefly described as follows: Fluorinated anhydride monomers, such as 6-FDA (hexafluorodianhydride), and other suitable diamine monomers are first dissolved separately in GBL (gamma-butyrolactone) solvent, and then slowly injected into a reaction vessel. The reaction vessel temperature is heated to 220℃, and an appropriate amount of catalyst is added and stirred for 5 hours. After cooling, an appropriate amount of GBL solvent is added for dilution to obtain PI. PI exhibits good temperature resistance, with a Tg (glass transition temperature) exceeding 300℃. Summary of the Invention

[0006] Therefore, the purpose of this invention is to solve the aforementioned problems in the prior art. This invention proposes a polyimide (PI) dielectric film for solid-state batteries and its manufacturing method. By adding a polyimide (PI) modifier, the surface stability of the solid electrolyte in the overall battery is enhanced. This effectively prevents the formation of unstable interface layers due to the reaction of LLZO with media such as air and water, thus avoiding the reduction of the solid electrolyte's performance and stability. Overall, this improves the interface stability of LLZO, enhances its ionic conductivity, thermal stability and chemical resistance, and improves the performance and lifespan of solid-state lithium batteries. The dielectric film of this invention can be widely used in solid-state lithium batteries, especially suitable for applications requiring high safety and stability, such as electric vehicles, energy storage systems, and aerospace. The dielectric film prepared using the method of this invention can significantly improve the overall performance and lifespan of solid-state lithium batteries, possessing significant technical value and market potential.

[0007] To achieve the above objectives, this invention proposes a dielectric film with PI for solid-state batteries, wherein the solid-state battery includes: a positive electrode, a negative electrode, and a dielectric film located between the positive electrode and the negative electrode; the dielectric film is composed of PVDF (polyvinylidene difluoride), multiple LLZO (lithium-lanthanum-zirconium oxide) particles, a polyimide (PI) modifier, and LiTFSI (LiN(CF3SO2)2, lithium bis(trifluoromethanesulfonyl)imide); wherein the polyimide (PI) modifier is a polymer material with good heat resistance, chemical resistance, and electrical insulation; mixing the polyimide (PI) modifier with the LLZO particles can effectively reduce the surface energy of the LLZO particles and improve the surface stability of the LLZO particles. In this dielectric film, the weight ratio of PVDF, polyimide (PI) modifier, multiple LLZO particles, and LiTFSI is 6~10:0.8~1.6:4~8:4~8, respectively. The total thickness of the dielectric film is between 10 micrometers and 20 micrometers.

[0008] This application also includes a method for manufacturing a dielectric film having PI, wherein the solid-state battery includes: a positive electrode, a negative electrode, and a dielectric film located between the positive electrode and the negative electrode; wherein the dielectric film is composed of PVDF (polyvinylidene difluoride), a plurality of LLZO (lithium-lanthanum-zirconium oxide) particles, a polyimide (PI) modifier, and LiTFSI (LiN(CF3SO2)2, lithium bis(trifluoromethanesulfonyl)imide); The manufacturing steps of this dielectric film include: Step A: taking multiple LLZO (lithium-lanthanum-zirconium-oxide) particles and a solvent, and mixing them using a first mixer to form a first slurry; wherein the solvent is selected from GBL (gamma-butyrolactone), DMAC (dimethylacetamide), or NMP (Methylpyrrolidone); Step B: taking PVDF (polyvinylidene oxide) particles... difluoride (polyvinylidene fluoride), polyimide (PI) modifier, AIBN (azobisisobutyronitrile), and LiTFSI (LiN(CF3SO2)2, lithium bis(trifluoromethanesulfonyl)imide); the above four compounds are mixed in a second mixer to form a second slurry; step C: the second slurry is added to the first slurry in a certain proportion to form a viscous mixed slurry; and step D: the viscous mixed slurry is coated on one side of the PET layer using a coating machine to form the mixed slurry layer, and the PET layer coated with the mixed slurry layer is placed in an oven for baking to remove the liquid in the mixed slurry layer; at this time, the mixed slurry layer will become a solid form dielectric film coated on the PET layer; step E: the solid form dielectric film is removed from the PET layer, and at this time the solid form dielectric film is used as the dielectric film located between the positive electrode and the negative electrode in the solid-state battery; The features and advantages of the invention will be further understood from the following description, and please refer to the accompanying drawings while reading. Attached Figure Description

[0009] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0010] Figure 1 This shows a structural diagram of the dielectric thin film of this application; Figure 2 This application shows a flowchart of the dielectric film manufacturing process; Figure 3 This application shows a schematic diagram of step A of the operation; Figure 4 This application shows schematic diagrams of steps B and C. Figure 5 This application shows a structural diagram of the dielectric film and the PET layer. Figure 6 This application shows a schematic diagram of step D of the operation. Figure 7 This shows a structural diagram of the solid-state battery of this application. Detailed Implementation

[0011] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0012] The following is a detailed description of a preferred embodiment of the present application, in conjunction with the accompanying drawings, regarding its structural composition, effects, and advantages.

[0013] Please refer to Figures 1 to 7 The diagram illustrates a PI-based dielectric thin film for solid-state batteries and a method for manufacturing the same, comprising the following components: like Figure 7 As shown, a typical solid-state battery includes: a positive electrode 10, a negative electrode 20, and a dielectric film 100 located between the positive electrode 10 and the negative electrode 20. The positive electrode 10 includes: a positive electrode substrate 11, a carrier material for supporting the positive electrode 10; a positive electrode slurry layer 12 coated on the positive electrode substrate 11, wherein the positive electrode slurry layer 12 includes: a positive electrode slurry 14 containing a binder; the positive electrode slurry 14 also includes a plurality of positive electrode particles 15, such as LCO (lithium cobalt oxide), NCM (lithium nickel cobalt manganese oxide), etc. The negative electrode 20 includes: a negative electrode substrate 21, a carrier material for supporting the negative electrode 20; a negative electrode slurry layer 22 coated on the negative electrode substrate 21, wherein the negative electrode slurry layer 22 includes: a negative electrode slurry 24 containing a binder; the negative electrode slurry 24 also includes a plurality of negative electrode particles 25, such as silicon carbide particles. The dielectric film 100 is located between the positive electrode 10 and the negative electrode 20, and is used to isolate the positive and negative electrodes and conduct lithium ions. The thickness of the dielectric film 100 is between 10 micrometers and 20 micrometers.

[0014] The dielectric film 100 is composed of PVDF (polyvinylidene difluoride) 40, multiple LLZO (lithium-lanthanum-zirconium oxide) particles 30, polyimide (PI) modifier 42, and LiTFSI (LiN(CF3SO2)2, lithium bis(trifluoromethanesulfonyl)imide) 46.

[0015] In the dielectric film 100, the weight ratio of the PVDF 40, the polyimide (PI) modifier 42, the plurality of LLZO particles 30, and the LiTFSI 46 is 6~16:0.8~2.8:4~14:4~14.

[0016] The dielectric film 100 has the following functions: improving mechanical strength to withstand the pressure during battery assembly, preventing dendrite growth and puncture, avoiding battery short circuits, improving ionic conductivity to meet the needs of high-power applications, and possessing excellent thermal and chemical stability, making it suitable for a wider operating temperature range and a longer service life.

[0017] In the aforementioned dielectric film 100, the PVDF 40 can be used as an adhesive and can also provide support properties to the dielectric film 100.

[0018] The polyimide modifier 42 is a polymer material with good heat resistance, chemical resistance, and electrical insulation. Mixing the polyimide modifier 42 with the LLZO particles 30 can effectively reduce the surface energy of the LLZO particles 30 and improve their surface stability.

[0019] The LLZO particles 30 are a solid electrolyte material with high ionic conductivity, good thermal stability and chemical resistance, and can be used as a lithium-ion conductor.

[0020] LiTFSI 46 is a lithium salt material that dissociates into lithium ions in a solvent, thereby increasing the conductivity of lithium ions. It can also be used to adjust the pH in the manufacturing process.

[0021] like Figures 2 to 6 The manufacturing steps of the dielectric film 100 are as follows: Step A: Multiple LLZO (lithium-lanthanum-zirconium-oxide) particles 30 and solvent 32 are taken and mixed using a first mixer 200 to form a first slurry 35. The total weight percentage of the multiple LLZO particles 30 in the first slurry 35 is between 20wt% and 40wt%. The first mixer 200 is selected from a ball mill or an ultrasonic mixer.

[0022] The solvent 32 is selected from GBL (gamma-Butyrolactone), DMAC (Dimethylacetamide), or NMP (Methylpyrrolidone), with DMAC being preferred. The main function of the solvent 32 is to disperse and support the plurality of LLZO particles 30 and the compounds added later.

[0023] The mixing time is approximately 30 minutes to 1 hour. After mixing, the particle size of each LLZO particle 30 is between 100 nanometers and 5 micrometers.

[0024] Step B: Take PVDF (polyvinylidene difluoride) 40, polyimide (PI) modifier 42, AIBN (azobisisobutyronitrile) 44, and LiTFSI (LiN(CF3SO2)2, lithium bis(trifluoromethanesulfonyl)imide) 46; mix the above four compounds 40, 42, 44, and 46 using a second mixer 220 to form a second slurry 45. This second mixer 220 can be a high-speed mechanical stirring device.

[0025] The PVDF 40 accounts for 30wt% to 50wt% of the weight of the second slurry 45; the total weight of the polyimide (PI) modifier 42 accounts for 4wt% to 8wt% of the weight of the second slurry 45; the total weight of the AIBN 44 accounts for approximately 1wt% to 2wt% of the weight of the second slurry 45; and the LiTFSI 46 accounts for 20wt% to 40wt% of the weight of the second slurry 45.

[0026] The PVDF 40 of this application can be used as an adhesive and can also provide support properties to the dielectric film 100.

[0027] The purpose of adding the polyimide (PI) modifier 42 is that polyimide is a polymer material with good heat resistance, chemical resistance and electrical insulation. Mixing the polyimide (PI) modifier 42 with the LLZO particles 30 can effectively reduce the surface energy of the LLZO particles 30 and improve the surface stability of the LLZO particles 30.

[0028] The primary function of adding AIBN 44 is to initiate a chelate reaction, thereby forming a cross-linked structure and enhancing the mechanical strength, chemical stability, and ionic conductivity of the electrolyte membrane. This is highly beneficial for improving the overall performance of the dielectric film in lithium-ion batteries.

[0029] LiTFSI 46 is a lithium salt material that dissociates into lithium ions in a solvent, thereby increasing the conductivity of lithium ions. It can also be used to adjust the pH in the manufacturing process.

[0030] Step C: The second slurry 45 is added to the first slurry 35 in a certain proportion to form a viscous mixed slurry 50. After mixing, the viscosity of the mixed slurry 50 is between 1500 and 5000 cps (centi-poise). After mixing, the content (solid content) of the components formed by the PVDF 40, the plurality of LLZO particles 30, the polyimide (PI) modifier 42 and the LiTFSI 46 in the entire mixed slurry 50 is 15wt% to 40wt%.

[0031] After mixing the first slurry 35 and the second slurry 45, the final mixed slurry 50 contains PVDF 40 at a weight percentage of 6 wt% to 16 wt%; polyimide (PI) modifier 42 at a weight percentage of 0.8 wt% to 2.8 wt%; the total weight of the plurality of LLZO particles 30 at a weight percentage of 4 wt% to 14 wt%; the total weight of LiTFSI 46 at a weight percentage of 4 wt% to 14 wt%; and the remainder being solvent 32 and AIBN 44. In the drying step described later, solvent 32 and AIBN 44 will evaporate or volatilize, leaving only the remaining substances.

[0032] Step D: The viscous slurry 50 is coated onto one side of a PET (polyethylene terephthalate) layer 101 using a coating machine 300 to form a slurry layer 55. The PET layer 101 coated with the slurry layer 55 is then placed in an oven 400 for baking to remove the liquid from the slurry layer 55. Before baking, the coating thickness of the slurry layer 55 is between 30 and 50 micrometers. After baking, only the PVDF 40, the multiple LLZO particles 30, the polyimide (PI) modifier 42, and the LiTFSI 46 remain in the slurry layer 55; the remaining substances evaporate during baking. At this point, the slurry layer 55 becomes a solid dielectric film 100 coated onto the PET layer 101. The overall thickness of the dielectric film 100 is between 10 and 20 micrometers.

[0033] The coating speed of the coating machine 300 is 5~10 m / min; the temperature of the oven 400 is 80°C~120°C, and the baking time is between 30 minutes and 1 hour.

[0034] Step E: The dielectric film 100 is removed from the PET layer 101. At this time, the dielectric film 100 can be used as the dielectric film between the positive electrode 10 and the negative electrode 20 in the solid-state battery.

[0035] The advantage of this application is that by adding a polyimide (PI) modifier, the solid electrolyte of the overall battery exhibits enhanced surface stability. This effectively prevents LLZO from reacting with media such as air and water to form an unstable interfacial layer, thus reducing the performance and stability of the solid electrolyte. Overall, it improves the interfacial stability, ionic conductivity, thermal stability, and chemical resistance of LLZO, and enhances the performance and lifespan of the solid-state lithium battery. The dielectric film of this invention can be widely used in solid-state lithium batteries, and is particularly suitable for applications requiring high safety and stability, such as electric vehicles, energy storage systems, and aerospace. The dielectric film prepared using the method of this invention can significantly improve the overall performance and lifespan of solid-state lithium batteries, possessing significant technical value and market potential.

[0036] In conclusion, the applicant's thoughtful and user-friendly design is highly in line with actual needs. Its specific improvements over existing deficiencies represent a significant breakthrough compared to existing technologies, offering genuine functional enhancements that are not easily achieved. This application has not been published or disclosed in domestic or foreign literature or markets, thus complying with patent law requirements.

[0037] The foregoing detailed description pertains to a feasible embodiment of the present invention. However, this embodiment is not intended to limit the scope of the patent of the present invention. All equivalent implementations or modifications that do not depart from the spirit of the present invention should be included in the scope of the patent of this application.

Claims

1. A PI-based dielectric thin film for use in solid-state batteries, characterized in that, The solid-state battery includes: a positive electrode, a negative electrode, and a dielectric film located between the positive electrode and the negative electrode; The dielectric film is composed of PVDF, multiple LLZO particles, a polyimide modifier, and LiTFSI.

2. The dielectric thin film according to claim 1, characterized in that, In this dielectric film, the weight ratio of the PVDF, the polyimide modifier, the plurality of LLZO particles, and the LiTFSI is 6~16:0.8~2.8:4~14:4~14.

3. The dielectric thin film according to claim 1, characterized in that, In this mixed slurry, the PVDF is used as an adhesive and also provides support for the dielectric film; the LLZO particles are used to conduct lithium ions; and the LiTFSI is a lithium salt material that increases the conductivity of lithium ions and can also be used to adjust the pH in the manufacturing process.

4. The dielectric thin film according to claim 1, characterized in that, The total thickness of the dielectric film is between 10 micrometers and 20 micrometers.

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