Lithium ion battery solid electrolyte membrane and preparation method thereof

Abstract

The invention discloses a lithium ion battery solid-state electrolyte membrane and a preparation method thereof, and relates to the technical field of solid-state batteries. According to the invention, the Fe / Ni-CuTCPP-Li < + > compound is added into the solid electrolyte membrane, and through bi-metal synergistic anchoring, three-dimensional pore channel confinement and local coordination regulation and control, the lithium ion transference number can be remarkably increased, and the interface impedance can be reduced. The solid-state electrolyte membrane can effectively improve the conductivity of the solid-state lithium battery, and has the potential of large-scale application.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a solid electrolyte membrane for lithium-ion batteries and its preparation method. Background Technology

[0002] Lithium-ion batteries, as core components of modern energy storage technology, have been deeply integrated into consumer electronics (mobile phones, computers, etc.) and new energy vehicles due to their high energy density (above 3500 mAh / g), long cycle life, and low self-discharge rate. However, the energy density of existing lithium-ion batteries is generally low, making it difficult to support the long-distance range requirements of electric vehicles. Lithium metal anodes, with their ultra-high theoretical capacity (3860 mAh / g) and lowest electrochemical potential, are considered key materials for breaking through the energy density bottleneck. However, they are prone to reacting with organic electrolytes in liquid electrolyte systems to form lithium dendrites, which can cause short circuits or even combustion and explosion.

[0003] Solid-state lithium metal batteries use solid electrolytes instead of liquid systems, possessing non-flammable properties and simultaneously improving safety and energy density (theoretically exceeding 500 Wh / kg), making them an important research direction for next-generation battery technology. To achieve fast charging and high power output, solid electrolytes need to possess high ionic conductivity (>10⁻³ S / cm), stable electrode / electrolyte interfaces, and mechanical strength. Polymer electrolytes (such as PEO and PVDF systems) show potential for large-scale application due to their flexible interface contact advantages, but their room-temperature ionic conductivity has long remained stagnant at around 10⁻³ S / cm. -6 ~10 -4 The low S / cm level necessitates high-temperature operation and limits rate performance of the battery. Specifically, low ionic conductivity means a high solid-solid interface energy barrier inside the solid-state battery, making lithium-ion transport difficult. This results in slow charge / discharge rates and poor rate performance of the finished solid-state battery, becoming a major obstacle to the widespread practical application of all-solid-state batteries.

[0004] Current polymer-based solid electrolytes often employ a multi-component strategy. For example, they utilize the synergistic effects of polymer matrices (such as PEO-PAN composites) with inorganic fillers (such as LiAlO2), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and ionic liquids to construct multi-pathway lithium-ion transport networks. Such composite systems can increase ionic conductivity to 10. -4 The S / cm scale and the interface polarization were mitigated by optimizing the lithium-ion transference number (>0.5). However, the complex preparation process (such as solution casting-hot pressing) resulted in high production costs, and the thin-layer technology (<50μm) still had problems such as low yield. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a solid electrolyte membrane for lithium-ion batteries and its preparation method, which improves the problems of low lithium-ion migration number and high interface impedance of solid electrolytes.

[0006] This invention proposes a solid electrolyte membrane for lithium-ion batteries, wherein the solid electrolyte membrane comprises lithium salt, polymer, and Fe / Ni-CuTCPP-Li + The composite, the Fe / Ni-CuTCPP-Li + The composite accounts for 0.5% to 15% of the total mass of the lithium salt and the polymer, for example, 0.5%, 1%, 2%, 3%, 5%, 10%, or 15%.

[0007] The Fe / Ni-CuTCPP-Li + The methods for preparing the complex include:

[0008] S1. Dissolve the iron source, nickel source and alkali source in deionized water and disperse them by ultrasonication to obtain a metal salt solution; dissolve tetracarboxyphenylporphyrin copper in a mixed solvent of N,N-dimethylformamide, methanol and glacial acetic acid to obtain a CuTCPP solution.

[0009] S2. The metal salt solution is added dropwise to the CuTCPP solution, heated and stirred until homogeneous, and then heated and reacted in a reaction vessel to obtain the Fe / Ni-CuTCPP composite.

[0010] S3. Add the Fe / Ni-CuTCPP complex to a lithium bis(trifluoromethanesulfonyl)imide solution, add a proton exchange aid, and stir to react, thus obtaining the final product.

[0011] This invention first utilizes an iron source, a nickel source, and CuTCPP (tetra(4-carboxyphenyl)porphyrin copper) to assemble via a solvothermal method to form an Fe / Ni-CuTCPP complex. Then, the Fe / Ni-CuTCPP complex is reacted with lithium bis(trifluoromethanesulfonyl)imide in the presence of a proton exchange aid. The proton exchange aid (e.g., a crown ether compound) can weaken the Li-N bond in LiTFSI through coordination, lowering the decomposition energy barrier and thus promoting the formation of lithiation sites (-COOLi) on the metalloporphyrin framework of the Fe / Ni-CuTCPP complex. Finally, lithiation is achieved through axial coordination of the porphyrin framework. + The loading forms Fe / Ni-CuTCPP-Li + The composite. This invention introduces Fe / Ni-CuTCPP-Li into a solid electrolyte membrane. + The composite material is used as an additive, Fe / Ni-CuTCPP-Li +The complex contains Fe / Ni oxygen clusters with highly electronegative oxygen atoms, which can effectively anchor anions (such as TFSI). - ), inhibit its migration, making Li + The proportion of the contributing current increases, while Li + The increase in the contribution current ratio (i.e., the mobility number) directly optimizes the charge transport efficiency and energy density of the battery. In high mobility number electrolytes, Li + More uniform flux distribution, avoiding localized Li + Depletion leads to dendrite nucleation, forming lithium dendrites; simultaneously, this Fe / Ni-CuTCPP-Li + The composite has a suitable framework pore size, allowing for the solvation of Li. + (Diameter ≈ 0.8 nm) can pass through, but it will block larger free anions, reduce the anion dragging effect, significantly reduce concentration polarization, and reduce side reactions such as anion reduction and decomposition, making the SEI film denser; Li + Embedding Cu-N4 axial vacancies can also form Cu-N4-Li + (Copper-tetranitrogen coordinated lithium ions) weaken the solvation sheath binding force, Cu-N4-Li + Weakening Li through coordination competition and electron delocalization + The binding force with solvent molecules (such as EC / DMC) increases the lithium-ion transference number; in addition, the porphyrin ring conjugation system enhances the binding force of Li... + The surrounding electron cloud density is redistributed, reducing its migration resistance. In summary, this invention utilizes Fe / Ni-CuTCPP-Li... + The bimetallic synergistic anchoring, three-dimensional pore confinement, and local coordination regulation of the composite can significantly improve the lithium-ion transference number and reduce interfacial impedance.

[0012] Preferably, the mass ratio of lithium salt to polymer is 1:1 to 20, for example, 1:1, 1:2, 1:3, 1:5, 1:10, or 1:20. By controlling the mass ratio of lithium salt to polymer, the battery can have better battery performance.

[0013] In this invention, the specific types of lithium salt and polymer are conventionally selected and can be adjusted according to actual needs. Preferably, the lithium salt is at least one of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate (LiClO4), lithium dioxaborate (LiBOB), and lithium nitrate (LiNO3); the polymer is at least one of polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polyvinylpyrrolidone, and polyvinylidene fluoride-block-polytetrafluoroethylene.

[0014] Preferably, in S1, the molar ratio of the iron source, nickel source, and alkali source is 1~3:1~5:2~7, and the ratio of the total molar amount of the iron source, nickel source, and alkali source to the molar amount of tetracarboxyphenylporphyrin copper is 5~10:1. By controlling the proportions of the iron source, nickel source, alkali source, and tetracarboxyphenylporphyrin copper, the structure and composition of the formed Fe / Ni-CuTCPP composite can be optimized, thereby further improving the lithium-ion transference number and more effectively enhancing the conductivity of the solid electrolyte membrane.

[0015] Preferably, in S1, the iron source is ferric nitrate, ferric chloride, or ferrous sulfate, preferably ferric chloride (FeCl3·6H2O); the nickel source is nickel nitrate, nickel chloride, or nickel sulfate, preferably nickel nitrate (Ni(NO3)2·6H2O).

[0016] Preferably, in S1, the alkali source is lithium carbonate, lithium hydroxide, sodium hydroxide, or potassium hydroxide; preferably, the alkali source is lithium carbonate or lithium hydroxide. When the above-mentioned alkali source is selected, no impurity elements are introduced, which is more beneficial to the performance of the solid electrolyte membrane; more preferably, the alkali source is lithium hydroxide (LiOH).

[0017] Preferably, in S1, the ratio of the total molar amount of the iron source, nickel source and alkali source to deionized water is 1~10 mmol: 20 mL.

[0018] Preferably, in S1, the concentration of the CuTCPP solution is 3.5~12mM.

[0019] In step S1, a mixed solvent of N,N-dimethylformamide, methanol, and glacial acetic acid is selected as the solvent system for the CuTPP solution. This solvent system uses N,N-dimethylformamide as the main solvent, which has high polarity and can effectively dissolve CuTCPP and metal salts. Methanol reduces the overall viscosity of the system, and acetic acid provides a weakly acidic environment, thereby promoting the reaction between CuTCPP and the metal salt. Preferably, in step S1, the mixed solvent of N,N-dimethylformamide, methanol, and glacial acetic acid is obtained by mixing N,N-dimethylformamide (DMF), methanol, and glacial acetic acid in a volume ratio of 3~9:1~7:1~7. By controlling the proportions of each component in the above mixed solvent, the reaction efficiency between the metal salt and CuTCPP can be increased, and the reaction can be more complete.

[0020] Preferably, in S1, the ultrasonic dispersion time is 0.1~4h.

[0021] Preferably, in step S2, the stirring temperature is 20~100℃ and the stirring time is 1h~8h.

[0022] Preferably, in step S2, the heating reaction temperature is 100~180℃ and the time is 10~60h. By controlling the temperature and time of the solvothermal reaction between the metal salt and CuTCPP in step S2, the reaction efficiency of the metal salt and CuTCPP can be increased and the reaction can be more complete.

[0023] In step S2, after the reaction is complete, conventional post-processing steps may be included, such as solid-liquid separation, washing, and drying. The solid-liquid separation can be performed using conventional methods, such as filtration and centrifugation; the solvent used for washing is preferably methanol, N,N-dimethylformamide, or a combination thereof.

[0024] Preferably, in step S3, the mass ratio of the Fe / Ni-CuTCPP composite to lithium bis(trifluoromethanesulfonyl)imide and the proton exchange aid is 1:1~3:0.05~0.45. By controlling the mass ratio of the above raw materials, the formed Fe / Ni-CuTCPP-Li can be further optimized. + The structure and composition of the composite are improved to further increase the lithium-ion transference number and more effectively enhance the conductivity of the solid electrolyte membrane.

[0025] Preferably, the proton exchange aid is a crown ether compound, and more preferably one or more of 18-crown ether-6, 15-crown ether-5, and N-methyl-18-crown-6.

[0026] Preferably, in step S3, the concentration of the lithium bis(trifluoromethanesulfonyl)imide solution is 0.5~2 mol / L.

[0027] Preferably, in S3, the solvent of the lithium bis(trifluoromethanesulfonyl)imide solution is one or more of acetonitrile, ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0028] Preferably, in step S3, the temperature of the stirred reaction is 20~100℃, and the time is 20~80h. By controlling the temperature and time of the reaction in step S3, the reaction efficiency of the Fe / Ni-CuTCPP complex with lithium bis(trifluoromethanesulfonylimide) can be increased, and the reaction can be more complete.

[0029] In step S2, after the reaction is complete, conventional post-processing steps may be included, such as solid-liquid separation, washing, and drying. The solid-liquid separation can be performed using conventional methods, such as filtration and centrifugation; the solvent used for washing is preferably methanol, N,N-dimethylformamide, or a combination thereof.

[0030] This invention also proposes a method for preparing the solid electrolyte membrane for lithium-ion batteries, comprising the following steps: adding a polymer to a solvent, heating to dissolve, then adding a lithium salt, stirring until fully dissolved, and then adding Fe / Ni-CuTCPP-Li +The composite material is stirred evenly to obtain a slurry; the slurry is coated onto a substrate to form a film, and then dried to obtain the final product.

[0031] The substrate can be made of materials commonly used in the art, such as glass or steel plates; the coating method can be a common method used in the art, such as scraping.

[0032] Preferably, in the preparation of the lithium-ion battery solid electrolyte membrane, the solvent is at least one selected from N-methylpyrrolidone (NMP), acetone, N,N-dimethylformamide, and ethanol.

[0033] Preferably, in the preparation of the lithium-ion battery solid electrolyte membrane, the drying temperature is 50~70℃ and the time is 20~30h.

[0034] The beneficial effects of this invention are as follows:

[0035] This invention introduces Fe / Ni-CuTCPP-Li into a solid electrolyte membrane. + In this complex, the highly electronegative oxygen atoms of the Fe / Ni oxygen cluster can effectively anchor anions (such as TFSI). - ), inhibit its migration, making Li + The contribution current ratio is increased, and the appropriate framework pore size allows for the solvation of Li. + (Diameter ≈ 0.8 nm) can pass through, but it will block larger free anions; Li + Embedding Cu-N4 axial vacancies can also form Cu-N4-Li + This weakens the solvation sheath binding force; furthermore, the porphyrin ring conjugated system makes Li... + The surrounding electron cloud density is redistributed, reducing its migration resistance. In summary, this invention utilizes Fe / Ni-CuTCPP-Li... + The bimetallic synergistic anchoring, three-dimensional pore confinement, and local coordination regulation of the composite material can significantly improve the lithium-ion transference number and reduce interfacial impedance. The solid electrolyte membrane of this invention can effectively improve the conductivity of solid-state lithium batteries and has the potential for large-scale application. Attached Figure Description

[0036] Figure 1 The lithium-ion transference number test results are for the solid polymer electrolyte membranes in Examples 1-2 and Comparative Examples 1-2.

[0037] Figure 2 The results are the interfacial impedance test results of the solid polymer electrolyte membranes in Examples 1-2 and Comparative Examples 1-2. Detailed Implementation

[0038] The technical solution of the present invention will now be described in detail through specific embodiments.

[0039] Example 1

[0040] A solid electrolyte membrane for lithium-ion batteries includes LiTFSI, polyvinylidene fluoride-block-polytetrafluoroethylene (PVDF-b-PTFE), and Fe / Ni-CuTCPP-Li. + The complex; wherein the mass ratio of LiTFSI to PVDF-b-PTFE is 1:3, and Fe / Ni-CuTCPP-Li + The composite accounts for 1% of the total mass of LiTFSI and PVDF-b-PTFE;

[0041] Among them, Fe / Ni-CuTCPP-Li + The preparation method of the complex is as follows:

[0042] S1. Dissolve 2 mmol FeCl3·6H2O, 1 mmol Ni(NO3)2·6H2O and 3 mmol LiOH in 20 mL of deionized water and sonicate for 20 min to obtain a metal salt solution; dissolve 1 mmol tetracarboxyphenylporphyrin copper in a mixed solvent to obtain a 5 mM CuTCPP solution, wherein the mixed solvent is obtained by mixing DMF, methanol and glacial acetic acid in a volume ratio of 8:1:1;

[0043] S2. The metal salt solution was added dropwise to the CuTCPP solution and stirred at 60°C for 2 hours. Then the mixture was transferred to a reaction vessel and reacted at 120°C for 40 hours. After the reaction was completed, the mixture was filtered, washed with methanol, and dried to obtain the Fe / Ni-CuTCPP composite.

[0044] S3. The Fe / Ni-CuTCPP complex was added to an acetonitrile solution of lithium bis(trifluoromethanesulfonyl)imide at a concentration of 1 mol / L, and 18-crown ether-6 was added. The mixture was stirred at 60 °C for 48 h. After the reaction was completed, the mixture was filtered, washed with methanol, and dried to obtain the final product. The mass ratio of Fe / Ni-CuTCPP complex, lithium bis(trifluoromethanesulfonyl)imide, and 18-crown ether-6 was 1:2:0.3.

[0045] The preparation method of the above-mentioned solid electrolyte membrane for lithium-ion batteries is as follows:

[0046] PVDF-b-PTFE was added to N-methylpyrrolidone and heated to dissolve at 60°C. Then, LiTFSI was added and stirred for 4 hours until fully dissolved. Finally, Fe / Ni-CuTCPP-Li was added. + The complex was stirred evenly to obtain a slurry with a solid content of 45%.

[0047] The slurry was coated onto a glass plate to form a film, and then placed in a vacuum drying oven and dried at 60°C for 24 hours to obtain a solid electrolyte membrane for lithium-ion batteries with a thickness of 20 μm.

[0048] Example 2

[0049] A solid electrolyte membrane for lithium-ion batteries includes LiTFSI, PVDF-b-PTFE, and Fe / Ni-CuTCPP-Li. + The complex; wherein the mass ratio of LiTFSI to PVDF-b-PTFE is 1:3, and Fe / Ni-CuTCPP-Li + The composite accounts for 10% of the total mass of LiTFSI and PVDF-b-PTFE;

[0050] Among them, Fe / Ni-CuTCPP-Li + The preparation method of the complex is the same as in Example 1;

[0051] The preparation method of the solid electrolyte membrane for lithium-ion batteries is the same as in Example 1, and the thickness of the solid electrolyte membrane obtained is 20 μm.

[0052] Example 3

[0053] A solid electrolyte membrane for lithium-ion batteries, comprising LiFSI, polyethylene oxide, and Fe / Ni-CuTCPP-Li + The complex; wherein the mass ratio of LiFSI to polyethylene oxide is 1:1, Fe / Ni-CuTCPP-Li + The mass of the composite accounts for 0.5% of the total mass of LiFSI and polyethylene oxide;

[0054] Among them, Fe / Ni-CuTCPP-Li + The preparation method of the complex is as follows:

[0055] S1. Dissolve 1 mmol FeCl3·6H2O, 1 mmol Ni(NO3)2·6H2O and 2 mmol LiOH in 20 mL of deionized water and sonicate for 20 min to obtain a metal salt solution; dissolve 0.8 mmol tetracarboxyphenylporphyrin copper in a mixed solvent to obtain a 5 mM CuTCPP solution, wherein the mixed solvent is obtained by mixing DMF, methanol and glacial acetic acid in a volume ratio of 3:1:1.

[0056] S2. The metal salt solution was added dropwise to the CuTCPP solution and stirred at 20°C for 1 h. Then it was transferred to a reaction vessel and reacted at 100°C for 10 h. After the reaction was completed, it was filtered, washed with methanol, and dried to obtain the Fe / Ni-CuTCPP complex.

[0057] S3. The Fe / Ni-CuTCPP complex was added to an acetonitrile solution of lithium bis(trifluoromethanesulfonyl)imide at a concentration of 0.5 mol / L, and 15-crown ether-5 was added. The mixture was stirred at 20 °C for 20 h. After the reaction was completed, the mixture was filtered, washed with methanol, and dried to obtain the final product. The mass ratio of Fe / Ni-CuTCPP complex, lithium bis(trifluoromethanesulfonyl)imide, and 15-crown ether-5 was 1:1:0.05.

[0058] The preparation method of the above-mentioned solid electrolyte membrane for lithium-ion batteries is as follows:

[0059] PVDF-b-PTFE was added to N-methylpyrrolidone and heated to dissolve at 60°C. Then, LiTFSI was added and stirred for 4 hours until fully dissolved. Finally, Fe / Ni-CuTCPP-Li was added. + The complex was stirred evenly to obtain a slurry with a solid content of 40%.

[0060] The slurry was coated onto a glass plate to form a film, and then placed in a vacuum drying oven and dried at 50°C for 20 hours to obtain a solid electrolyte membrane for lithium-ion batteries with a thickness of 16 μm.

[0061] Example 4

[0062] A solid electrolyte membrane for lithium-ion batteries, comprising LiNO3, polyvinylidene fluoride, and Fe / Ni-CuTCPP-Li + The composite material; wherein the mass ratio of LiNO3 to polyvinylidene fluoride is 1:20, and Fe / Ni-CuTCPP-Li + The composite accounts for 15% of the total mass of LiNO3 and polyvinylidene fluoride;

[0063] Among them, Fe / Ni-CuTCPP-Li + The preparation method of the complex is as follows:

[0064] S1. Dissolve 1.5 mmol FeCl3·6H2O, 2.5 mmol Ni(NO3)2·6H2O and 3.5 mmol LiOH in 20 mL of deionized water and sonicate for 20 min to obtain a metal salt solution; dissolve 1 mmol tetracarboxyphenylporphyrin copper in a mixed solvent to obtain a 10 mM CuTCPP solution, wherein the mixed solvent is obtained by mixing DMF, methanol and glacial acetic acid in a volume ratio of 9:7:7;

[0065] S2. The metal salt solution was added dropwise to the CuTCPP solution and stirred at 90°C for 6 hours. Then the mixture was transferred to a reaction vessel and reacted at 180°C for 60 hours. After the reaction was completed, the mixture was filtered, washed with methanol, and dried to obtain the Fe / Ni-CuTCPP composite.

[0066] S3. The Fe / Ni-CuTCPP complex was added to an acetonitrile solution of lithium bis(trifluoromethanesulfonyl)imide at a concentration of 2 mol / L, and N-methyl-18-crown-6 was added. The mixture was stirred at 90 °C for 80 h. After the reaction was completed, the mixture was filtered, washed with methanol, and dried to obtain the final product. The mass ratio of Fe / Ni-CuTCPP complex, lithium bis(trifluoromethanesulfonyl)imide, and N-methyl-18-crown-6 was 1:3:0.45.

[0067] The preparation method of the above-mentioned solid electrolyte membrane for lithium-ion batteries is as follows:

[0068] PVDF-b-PTFE was added to N-methylpyrrolidone and heated to dissolve at 60°C. Then, LiTFSI was added and stirred for 4 hours until fully dissolved. Finally, Fe / Ni-CuTCPP-Li was added. + The complex was stirred evenly to obtain a slurry with a solid content of 60%.

[0069] The slurry was coated onto a glass plate to form a film, and then placed in a vacuum drying oven and dried at 70°C for 30 hours to obtain a solid electrolyte membrane for lithium-ion batteries with a thickness of 40 μm.

[0070] Comparative Example 1

[0071] A solid electrolyte membrane for lithium-ion batteries includes LiTFSI and PVDF-b-PTFE; wherein the mass ratio of LiTFSI to PVDF-b-PTFE is 1:3.

[0072] The preparation method of the above-mentioned solid electrolyte membrane for lithium-ion batteries is as follows:

[0073] PVDF-b-PTFE was added to N-methylpyrrolidone and heated to dissolve at 60°C. Then LiTFSI was added and stirred for 4 hours until fully dissolved to obtain a slurry with a solid content of 45%.

[0074] The slurry was coated onto a glass plate to form a film, and then placed in a vacuum drying oven and dried at 60°C for 24 hours to obtain a solid electrolyte membrane for lithium-ion batteries with a thickness of 20 μm.

[0075] Comparative Example 2

[0076] A solid electrolyte membrane for lithium-ion batteries includes LiTFSI, PVDF-b-PTFE, and copper tetracarboxyphenylporphyrin; wherein the mass ratio of LiTFSI to PVDF-b-PTFE is 1:3, and the mass of copper tetracarboxyphenylporphyrin accounts for 10% of the total mass of LiTFSI and PVDF-b-PTFE;

[0077] The preparation method of the above-mentioned solid electrolyte membrane for lithium-ion batteries is as follows:

[0078] PVDF-b-PTFE was added to N-methylpyrrolidone and heated to dissolve at 60°C. Then LiTFSI was added and stirred for 4 hours until fully dissolved. Tetracarboxyphenylporphyrin copper was then added and stirred until homogeneous to obtain a slurry with a solid content of 45%.

[0079] The slurry was coated onto a glass plate to form a film, and then placed in a vacuum drying oven and dried at 60°C for 24 hours to obtain a solid electrolyte membrane for lithium-ion batteries with a thickness of 20 μm.

[0080] The solid polymer electrolyte membranes from Examples 1-2 and Comparative Examples 1-2 were tested for lithium-ion transference number and interfacial impedance. The test results are as follows:

[0081] The test results for lithium-ion transference numbers are listed in Figure 1 In Comparative Example 1, the lithium-ion transference number of the pure polymer electrolyte membrane was only 0.28. Examples 1 and 2 showed different amounts of Fe / Ni-CuTCPP-Li added. + The lithium-ion transference numbers of the solid electrolyte membrane of the composite were 0.58 and 0.82, respectively, which were significantly improved compared with the pure polymer electrolyte membrane. In contrast, the lithium-ion transference number of the solid electrolyte membrane with CuTCPP added in Comparative Example 2 was only 0.33, showing no significant improvement. This is because the ion transport capacity of the monomeric porphyrin copper is limited due to the coordination saturation of the central copper ion, resulting in a low intrinsic ion transference number. The Fe / Ni-CuTCPP-Li... + The Fe / Ni oxygen cluster in the complex possesses highly electronegative oxygen atoms, which, along with TFSI - It forms a strong anchoring effect, inhibits its migration, and is beneficial to the transport of lithium ions.

[0082] The test results of the interface impedance are listed in Figure 2 In the comparative example 1, the interfacial impedance of the pure polymer electrolyte membrane was 128 Ω·cm. 2 Examples 1 and 2 show the addition of different amounts of Fe / Ni-CuTCPP-Li. + The interfacial impedance of the solid electrolyte membrane of the composite is 74 Ω·cm. 2 48 Ω·cm 2 Compared to the pure polymer electrolyte membrane, the interfacial impedance decreased significantly, while the interfacial impedance of the solid electrolyte membrane with CuTCPP added in Comparative Example 2 was 113 Ω·cm. 2 The decrease was not significant. This is because the electrolyte membrane in the embodiment contained Fe / Ni-CuTCPP-Li. + Complex, wherein Li + Cu-N4-Li is formed by embedding axial vacancies in Cu-N4. + This improves the solvation ability of LiTFSI and reduces the solvation energy. A low solvation energy can effectively reduce interfacial impedance.

[0083] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A solid electrolyte membrane for lithium-ion batteries, characterized in that, The solid electrolyte membrane comprises lithium salt, polymer, and Fe / Ni-CuTCPP-Li. + The composite, the Fe / Ni-CuTCPP-Li + The mass of the composite accounts for 0.5% to 15% of the total mass of the lithium salt and the polymer; The Fe / Ni-CuTCPP-Li + The methods for preparing the complex include: S1. Dissolve the iron source, nickel source and alkali source in deionized water and disperse them by ultrasonication to obtain a metal salt solution; Copper tetracarboxyphenylporphyrin was dissolved in a mixed solvent of N,N-dimethylformamide, methanol, and glacial acetic acid to obtain a CuTCPP solution. S2. The metal salt solution is added dropwise to the CuTCPP solution, stirred evenly, and then heated in a reaction vessel to obtain the Fe / Ni-CuTCPP composite. S3. The Fe / Ni-CuTCPP complex is added to a lithium bis(trifluoromethanesulfonyl)imide solution, and a proton exchange aid is added. The mixture is stirred to react, yielding Fe / Ni-CuTCPP-Li. + Complex.

2. The lithium-ion battery solid electrolyte membrane according to claim 1, characterized in that, The mass ratio of the lithium salt to the polymer is 1:1 to 20.

3. The solid electrolyte membrane for lithium-ion batteries according to claim 1, characterized in that, The lithium salt is at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium dioxaborate, and lithium nitrate; the polymer is at least one of polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polyvinylpyrrolidone, and polyvinylidene fluoride-block-polytetrafluoroethylene.

4. The lithium-ion battery solid electrolyte membrane according to claim 1, characterized in that, In S1, the molar ratio of the iron source, nickel source and alkali source is 1~3:1~5:2~7, and the ratio of the total molar amount of the iron source, nickel source and alkali source to the molar amount of tetracarboxyphenylporphyrin copper is 5~10:

1.

5. The lithium-ion battery solid electrolyte membrane according to claim 1, characterized in that, In S1, the mixed solvent of N,N-dimethylformamide, methanol, and glacial acetic acid is obtained by mixing N,N-dimethylformamide, methanol, and glacial acetic acid in a volume ratio of 3~9:1~7:1~7.

6. The lithium-ion battery solid electrolyte membrane according to claim 1, characterized in that, In S2, the heating reaction temperature is 100~180℃ and the time is 10~60h.

7. The lithium-ion battery solid electrolyte membrane according to claim 1, characterized in that, In S3, the mass ratio of the Fe / Ni-CuTCPP complex to lithium bis(trifluoromethanesulfonylimide) and the proton exchange aid is 1:1~3:0.05~0.

45.

8. The lithium-ion battery solid electrolyte membrane according to claim 1, characterized in that, The proton exchange aid is one or more of 18-crown ether-6, 15-crown ether-5, and N-methyl-18-crown-6.

9. The solid electrolyte membrane for lithium-ion batteries according to claim 1, characterized in that, In S3, the temperature of the stirring reaction is 20~100℃, and the time is 20~80h.

10. A method for preparing a solid electrolyte membrane for a lithium-ion battery as described in any one of claims 1 to 9, characterized in that, The process includes the following steps: adding the polymer to a solvent, heating to dissolve, then adding the lithium salt, stirring until fully dissolved, and finally adding Fe / Ni-CuTCPP-Li. + The composite material is stirred evenly to obtain a slurry; the slurry is coated onto a substrate to form a film, and then dried to obtain the final product.

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