Metal halide-modified pvdf-based composite solid electrolyte, preparation method and application
By doping metal halide nanomaterials into PVDF-based electrolytes, metal halide-modified PVDF-based composite solid electrolytes were prepared, which solved the problem of low room temperature ionic conductivity of PVDF-based electrolytes, improved battery performance, and simplified the preparation process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2026-04-30
- Publication Date
- 2026-07-24
AI Technical Summary
The low room-temperature ionic conductivity of existing PVDF-based solid electrolytes limits their application in high-performance batteries, and the introduction of inorganic fillers is complex and has limited effect on improving the ionic conductivity of the polymer matrix.
Metal halide nanomaterials are uniformly doped into PVDF polymer electrolytes. The metal halide nanomaterials are combined with PVDF and lithium salts through a preparation method to form a metal halide-modified PVDF-based composite solid electrolyte.
It significantly improves the room temperature ionic conductivity of PVDF-based composite solid electrolytes, enhances the electrochemical performance of batteries, and simplifies the preparation process.
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Abstract
Description
Technical Field
[0001] This invention relates to a metal halide-modified PVDF-based composite solid electrolyte, its preparation method, and its application, belonging to the field of new energy battery materials technology. Background Technology
[0002] Solid-state electrolytes, as an important alternative to traditional liquid electrolytes, have attracted widespread attention due to their superior safety and thermal stability. Among them, polyvinylidene fluoride (PVDF)-based electrolytes have become a research hotspot due to their flexibility and high adaptability to traditional processes. However, the poor room-temperature ionic conductivity of PVDF-based electrolytes limits their application in high-performance batteries.
[0003] In recent years, inorganic materials have been widely used in polymer-based composite solid electrolytes to improve their room-temperature conductivity. Patent application CN119481240A discloses a composite solid electrolyte and its preparation method, wherein the concentration of a superionic conductor in the composite solid electrolyte is 40-90 wt%, and the concentration of graphene oxide is 0.1-2 wt%. The PVDF-superionic conductor-GO composite electrolyte prepared by combining a superionic conductor and graphene oxide improves ion transport capability. Patent application CN116742143A discloses a method for preparing a zirconium oxide / PVDF-based polymer solid electrolyte, wherein a zirconium-based metal oxide ceramic filler is used to dope the PVDF-based polymer composite electrolyte, resulting in an electrolyte membrane with high ionic conductivity at room temperature.
[0004] Although some progress has been made in the research of inorganic-organic composite solid electrolytes, their preparation methods are relatively complex, which is not conducive to industrial production. At the same time, the introduced inorganic fillers lack interaction with the polymer matrix material, resulting in limited improvement on the intrinsic ionic conductivity of the polymer matrix. Summary of the Invention
[0005] In view of this, the purpose of the present invention is to provide a metal halide-modified PVDF-based composite solid electrolyte, its preparation method and application.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows.
[0007] A metal halide-modified PVDF-based composite solid electrolyte is composed of metal halide nanomaterials and PVDF polymer electrolyte. The metal halide nanomaterials are uniformly doped in the PVDF polymer electrolyte, which includes PVDF and lithium salt. The metal halide nanomaterials account for 0.5 wt% to 1.5 wt% of the PVDF by mass.
[0008] Preferably, the metal halide nanomaterial is one or more selected from PbI2, PbCl2, PbBr2, AlCl3, and FeCl3. More preferably, the metal halide nanomaterial is PbI2.
[0009] Preferably, in the PVDF polymer electrolyte, the mass ratio of PVDF to lithium salt is 1.4 to 1.6:1. More preferably, the mass ratio of PVDF to lithium salt is 1.5:1.
[0010] Preferably, the weight-average molecular weight of the PVDF is 400,000 to 600,000.
[0011] Preferably, the particle size of the composite solid electrolyte is 4~5μm.
[0012] Preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and / or lithium bis(fluorosulfonyl)imide (LiFSI). More preferably, the lithium salt is LiFSI.
[0013] A method for preparing a metal halide-modified PVDF-based composite solid electrolyte, comprising the following steps:
[0014] (1) Add PVDF and lithium salt to N,N-dimethylformamide (DMF, analytical grade) and stir for 5-6 h to obtain a polymer electrolyte solution; (2) Add the metal halide nanomaterials to DMF and stir for 4-5 hours to obtain a metal halide solution; (3) Add the metal halide solution to the polymer electrolyte solution and stir for 5-7 hours to obtain the precursor solution; (4) The precursor solution was poured into the template and annealed at 45~65℃ for 6~7h to obtain the metal halide modified PVDF-based composite solid electrolyte.
[0015] Preferably, in step (1), the concentration of PVDF in the polymer electrolyte solution is 80~120 mg / mL.
[0016] Preferably, in step (1), the stirring rate is 200~300 rpm.
[0017] Preferably, in step (2), the solubility of the metal halide in the metal halide solution is 0.80~2.50 mg / mL.
[0018] Preferably, in step (2), the stirring rate is 300~500 rpm.
[0019] Preferably, in step (3), the stirring rate is 200~300 rpm.
[0020] Preferably, in step (4), the casting rate of the precursor solution is 0.5~1.5 mL / s, and the PVDF casting content is 4~6 mg / cm³. 2 .
[0021] The application of a metal halide-modified PVDF-based composite solid electrolyte as an electrolyte for an all-solid-state lithium-ion battery, wherein the all-solid-state lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte.
[0022] Preferably, the active material of the positive electrode includes lithium iron phosphate, ternary nickel cobalt manganese (type 111, type 523, type 622 or type 811), lithium cobalt oxide, and lithium manganese oxide; the active material of the negative electrode includes lithium metal, graphite, silicon carbide, and silicon.
[0023] Beneficial effects In this invention, metal halide nanomaterials are uniformly doped into PVDF polymer electrolyte. The metal halide nanomaterials can effectively reduce the crystal strength of the (200) crystal plane of PVDF polymer electrolyte. The reduction in crystallinity can effectively improve the ionic conductivity of the material at room temperature. At the same time, the uniform distribution of metal halides in the polymer matrix material can further enhance the electrochemical performance of the battery. Attached Figure Description
[0024] Figure 1 The images show the XRD patterns of the solid electrolytes prepared in Example 1 and Comparative Example 1.
[0025] Figure 2 The images shown are optical photographs and corresponding SEM images of the solid electrolyte prepared in Example 1.
[0026] Figure 3 This is an elemental distribution diagram of the solid electrolyte prepared in Example 1.
[0027] Figure 4 The image shows the EIS diagrams of the solid electrolytes prepared in Example 1 and Comparative Example 1 at room temperature.
[0028] Figure 5 The images show Tafel diagrams of the solid electrolytes prepared in Example 1 and Comparative Example 1 at room temperature.
[0029] Figure 6 This is a graph showing the charge-discharge curves at room temperature of the Li|| ternary nickel-cobalt-manganese all-solid-state battery assembled with the solid electrolyte prepared in Example 1. Detailed Implementation
[0030] The present invention will be further described in detail below with reference to specific embodiments.
[0031] Example 1 The preparation method of the PVDF-based composite solid electrolyte in this embodiment is as follows: (1) Weigh 0.5 g PVDF (weight average molecular weight of 400,000) and 0.33 g LiFSI, mix them in a 10 mL reagent bottle, add 5 mL DMF solvent and a magnetic stir bar, stir at room temperature for 6 h at 250 rpm to obtain a pure PVDF solid electrolyte precursor solution.
[0032] Weigh 0.005 g of PbI2 and dissolve it in 3 mL of DMF. Stir at room temperature for 5 h at 500 rpm to obtain a metal halide precursor solution.
[0033] The fully dissolved metal halide precursor solution and the pure PVDF solid electrolyte precursor solution were mixed and stirred at room temperature for 6 h at 250 rpm to obtain the composite solid electrolyte precursor solution. The metal halide in the composite solid electrolyte precursor solution accounted for 1 wt% of the PVDF mass.
[0034] (2) The composite solid electrolyte precursor solution is poured into a container with a size of 10×10 cm. 2 A polytetrafluoroethylene template was slowly poured at a rate of 0.5 mL / s to evenly cover the entire template. The template was then annealed at 45°C for 6 hours on a hot plate to obtain a uniform composite solid electrolyte film.
[0035] (3) The prepared solid electrolyte membrane is punched out with a diameter of 19 mm using a circular metal punch for use in CR2032 button cell assembly.
[0036] (4) The specific operations for preparing solid-state batteries are as follows: The ternary nickel-cobalt-manganese (811 type) positive electrode is stamped into a circular electrode sheet with a diameter of 11 mm. Using metallic lithium as the negative electrode, it is stamped and assembled into a CR2032 type button cell in a glove box.
[0037] The entire preparation process was carried out in an argon atmosphere glove box (both water and oxygen content ≤0.01ppm).
[0038] The room-temperature ionic conductivity of the composite solid electrolyte was determined to be 2.7 × 10⁻⁶ by electrochemical impedance spectroscopy (EIS). -4 Scm -1 .
[0039] Example 2 Example 1 was repeated, except that the metal halide in the composite solid electrolyte precursor solution accounted for 0.5 wt% of the mass of PVDF.
[0040] The room temperature ionic conductivity of the metal halide-modified PVDF-based composite solid electrolyte is 2.2 × 10⁻⁶. -4 S cm -1 .
[0041] Example 3 Example 1 was repeated, except that the metal halide in the composite solid electrolyte precursor solution accounted for 1.5 wt% of the PVDF.
[0042] The room temperature ionic conductivity of the metal halide-modified PVDF-based composite solid electrolyte is 2.1 × 10⁻⁶. -4 S cm -1 .
[0043] Comparative Example 1 The only difference from Example 1 is that no metal halide nanomaterials are added.
[0044] The room temperature ionic conductivity of the PVDF-based electrolyte is 1.5 × 10⁻⁶. -4 S cm -1 .
[0045] Figure 1 These are the X-ray diffraction (XRD) patterns of the solid electrolyte membranes prepared in Example 1 and Comparative Example 1. The XRD diffraction pattern of the metal halide-modified PVDF-based composite solid electrolyte membrane shows significant differences compared to the comparative example. This is mainly due to the differences in XRD patterns between the two examples. =13.1° and 2 The presence of characteristic PbI2 (001) and (011) crystal planes at 25.9° indicates that PbI2 is precisely incorporated into the PVDF polymer electrolyte. Simultaneously, the composite solid electrolyte membrane at 2°... PVDF at =20.7° The crystal strength of the characteristic crystal facet of crystal form (200) decreased by 15%, indicating that the introduction of metal halide can effectively reduce the crystallinity of the polymer and enhance its ionic pathway.
[0046] Figure 2 The 19mm circular electrolyte membrane punched from the composite solid electrolyte prepared in Example 1 exhibits a uniform and consistent appearance on a macroscopic scale, with no obvious thickness variations. Furthermore, scanning electron microscopy (SEM) was used to observe the microstructure of the composite solid electrolyte prepared in Example 1, revealing a densely packed composite microsphere structure with a uniform distribution of 4–5 μm. This uniform and dense distribution effectively enhances the ionic conductivity of the composite solid electrolyte.
[0047] Figure 3This is the elemental distribution of the composite solid electrolyte prepared in Example 1. Elemental distribution analysis was performed on the electrolyte cross-section, and the detected elements included: carbon (C), fluorine (F), iodine (I), and lead (Pb). In particular, the surface undulations caused by cross-sectional sample preparation affected the signal acquisition intensity of the energy dispersive spectrometer; carbon and fluorine are characteristic elements of the PVDF matrix material. Lead iodide was uniformly distributed and deposited in the PVDF matrix.
[0048] Figure 4 Electrochemical impedance spectroscopy was performed on the solid electrolytes prepared in Example 1 and Comparative Example 1. Ionic conductivity was calculated using the formula... The calculation yielded the result. Here, L represents the thickness of the solid electrolyte (L = 100 μm), and S is the effective contact area (2.01 cm²). 2 R represents the impedance of the electrolyte. The test environment conditions comply with GB / T 31486-2024 standard: the test should be conducted in an environment with a temperature of room temperature (25℃±2℃), a relative humidity of 10%~90%, and an atmospheric pressure of 86 kPa~106 kPa. Figure 4 The resistance of different electrolyte membranes can be obtained from the EIS spectrum. The resistance of the solid electrolyte prepared in Example 1 is R = 18.23. The resistance R of the solid electrolyte prepared in Comparative Example 1 is 33.56 Ω. Further calculations yielded the room-temperature ionic conductivity of the solid electrolyte prepared in Example 1. 2.7×10 -4 S cm -1 The room temperature ionic conductivity of the solid electrolyte prepared in Comparative Example 1 1.5×10 -4 S cm -1 Therefore, the metal halide-modified PVDF-based composite solid electrolyte (Example 1) increased the room temperature conductivity of the polymer solid electrolyte (Comparative Example 1) by 1.8 times.
[0049] Figure 5 These are Tafel plots of the solid electrolytes prepared in Example 1 and Comparative Example 1 at room temperature. Tafel polarization measurements were used to quantify the exchange current density at the lithium metal-solid electrolyte interface. Figure 5 As shown, the interface exchange current density in Example 1 is 0.39 mA cm⁻¹. -2 The interface exchange current density is 0.25 mA cm⁻¹ higher than that of Comparative Example 1. -2 This indicates a significant improvement in interfacial ion transport kinetics, demonstrating that metal halide-modified PVDF solid electrolytes can effectively enhance the stable transport of ions at the interface.
[0050] Figure 6This is a charge-discharge curve of a Li|| ternary nickel-cobalt-manganese all-solid-state battery assembled with the composite solid electrolyte prepared in Example 1, measured at room temperature. Charge-discharge tests were conducted at a rate of 1C in an atmospheric environment at room temperature (voltage range 2.8-4.3 V): the first discharge specific capacity was 169.1 mAh g⁻¹. -1 After 10 charge-discharge cycles, it maintains a capacity of 165.3 mAh g. -1 The discharge specific capacity was high, with a capacity retention rate of 97.8%. This indicates that the technology has great potential for improving the performance of polymer-based solid electrolytes and batteries.
[0051] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.
Claims
1. A metal halide-modified PVDF-based composite solid electrolyte, characterized in that: It is composed of metal halide nanomaterials and PVDF polymer electrolyte. The metal halide nanomaterials are uniformly doped in the PVDF polymer electrolyte, which includes PVDF and lithium salt. The metal halide nanomaterials account for 0.5 wt% to 1.5 wt% of the PVDF by mass.
2. The PVDF-based composite solid electrolyte modified with metal halide as described in claim 1, characterized in that: The metal halide nanomaterial is one or more of PbI2, PbCl2, PbBr2, AlCl3, and FeCl3.
3. The PVDF-based composite solid electrolyte modified with metal halide as described in claim 1, characterized in that: In the PVDF polymer electrolyte, the mass ratio of PVDF to lithium salt is 1.4~1.6:1; Preferably, the weight-average molecular weight of the PVDF is 400,000 to 600,000; Preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide and / or lithium bis(fluorosulfonyl)imide.
4. The PVDF-based composite solid electrolyte modified with metal halide as described in claim 1, characterized in that: The particle size of the composite solid electrolyte is 4~5μm.
5. A method for preparing a metal halide-modified PVDF-based composite solid electrolyte according to any one of claims 1 to 4, characterized in that: The method steps include: (1) Add PVDF and lithium salt to DMF and stir for 5-6 hours to obtain a polymer electrolyte solution; (2) Add the metal halide nanomaterials to DMF and stir for 4-5 hours to obtain a metal halide solution; (3) Add the metal halide solution to the polymer electrolyte solution and stir for 5-7 hours to obtain the precursor solution; (4) The precursor solution was poured into the template and annealed at 45~65℃ for 6~7h to obtain the metal halide modified PVDF-based composite solid electrolyte.
6. The method for preparing a metal halide-modified PVDF-based composite solid electrolyte as described in claim 5, characterized in that: In step (1), the concentration of PVDF in the polymer electrolyte solution is 80~120 mg / mL; Preferably, in step (1), the stirring rate is 200~300 rpm.
7. The method for preparing a metal halide-modified PVDF-based composite solid electrolyte as described in claim 5, characterized in that: In step (2), the solubility of the metal halide in the metal halide solution is 0.80~2.50 mg / mL; Preferably, in step (2), the stirring rate is 300~500 rpm.
8. The method for preparing a metal halide-modified PVDF-based composite solid electrolyte as described in claim 5, characterized in that: In step (3), the stirring speed is 200~300 rpm.
9. The method for preparing a metal halide-modified PVDF-based composite solid electrolyte as described in claim 5, characterized in that: In step (4), the casting rate of the precursor solution is 0.5~1.5 mL / s, and the PVDF casting content is 4~6 mg / cm³. 2 .
10. The application of a metal halide-modified PVDF-based composite solid electrolyte as described in any one of claims 1 to 4 as an electrolyte for an all-solid-state lithium-ion battery, wherein the all-solid-state lithium-ion battery comprises a positive electrode, a negative electrode, and an electrolyte; Preferably, the active material of the positive electrode includes lithium iron phosphate, ternary nickel cobalt manganese, lithium cobalt oxide, and lithium manganese oxide; the active material of the negative electrode includes lithium metal, graphite, silicon carbide, and silicon.