Functionalized double-metal phthalocyanine moF materials, methods of preparation, modified separators, and batteries
By modifying the separator with functionalized bimetallic phthalocyanine MOF material, the problem of high-temperature cycle life of lithium-ion batteries was solved. By adsorbing trace amounts of moisture and dissolving metal ions, side reaction chains were blocked, achieving efficient life extension and enhanced stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG GEELY HLDG GRP CO LTD
- Filing Date
- 2026-01-20
- Publication Date
- 2026-06-09
AI Technical Summary
The high-temperature cycle life of existing lithium-ion batteries is affected by the side reactions caused by the dissolution of transition metals in the cathode material and trace amounts of moisture. Existing technologies cannot suppress metal dissolution and hydrolysis reactions at the source.
A membrane was modified with a functionalized bimetallic phthalocyanine MOF material. By coating the membrane surface with the functionalized bimetallic phthalocyanine MOF material, trace amounts of moisture and dissolved metal ions were adsorbed. The side reaction chain was blocked by utilizing its porous structure and the chemical coordination effect of the metal center.
It significantly improves the high-temperature cycle life of lithium-ion batteries by approximately 37%, maintains good performance under high moisture conditions, and has a simple material synthesis process that is compatible with existing production lines.
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Figure CN122167756A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery preparation, and particularly to a functionalized bimetallic phthalocyanine MOF material, its preparation method, its modified separator, and the battery thereof. Background Technology
[0002] With the booming development of the new energy vehicle industry, lithium-ion batteries have been widely used. However, the lifespan of lithium-ion batteries, especially their high-temperature cycle life, still faces severe challenges. Transition metals (such as iron and manganese) in cathode materials (e.g., lithium iron phosphate, lithium-rich manganese-based materials) dissolve during cycling. Simultaneously, trace amounts of moisture, difficult to completely avoid during cell manufacturing, trigger a series of side reactions. Specifically, lithium hexafluorophosphate in the electrolyte hydrolyzes in the presence of water to produce hydrofluoric acid. HF attacks the cathode material lattice, exacerbating the dissolution of transition metals. The dissolved metal ions migrate to the anode, damaging the solid electrolyte interface film and catalyzing electrolyte decomposition, leading to rapid capacity decay and increased internal resistance.
[0003] Existing technologies include several methods for adsorbing and dissolving metal ions through membrane modification. For example, one technique involves coating one side of the base membrane with a hypercrosslinked polymer coating to adsorb metal ions by controlling the pore size; another technique modifies the surface of the base membrane with porphyrin MOF to adsorb metal ions through physical adsorption and chemical coordination; still another technique uses LiOH or small-pore metal oxide particles to address metal dissolution through precipitation or physical blocking.
[0004] However, these existing technologies all have varying degrees of drawbacks: the hypercrosslinked polymer coating process is complex and costly; long-term LiOH cycling may clog the membrane pores; small-particle oxides can increase the membrane's internal resistance; and porphyrin materials are expensive and difficult to prepare. More importantly, the above solutions all focus on treating the dissolved metal ions, rather than inhibiting the side reactions that lead to metal dissolution at the source—namely, the removal of trace amounts of water in the electrolyte. Summary of the Invention
[0005] To address the aforementioned issues, this invention provides a functionalized bimetallic phthalocyanine MOF (metal-organic framework) material, its preparation method, a modified separator, and a battery. By coating the separator surface with this functionalized bimetallic phthalocyanine MOF material, the absorption of trace amounts of moisture in lithium-ion batteries and the adsorption of metals dissolved from the cathode can be achieved simultaneously, thereby improving the dissolution of cathode metals from the source. Furthermore, the material used in this invention has advantages such as simple synthesis and compatibility with existing production lines.
[0006] In a first aspect, the present invention provides a functionalized bimetallic phthalocyanine MOF material, wherein the center of the functionalized bimetallic phthalocyanine MOF material simultaneously possesses two metal ions M with different valence states.n+ The functionalized bimetallic phthalocyanine MOF material has an electron-withdrawing functional group R grafted onto the peripheral benzene ring of the phthalocyanine ligand, and the two metal ions with different valence states include divalent metal ions and trivalent metal ions.
[0007] In one embodiment of the present invention, the morphology of the functionalized bimetallic phthalocyanine MOF material is nanosheet with an average size of 150-250 nm, such as 150 nm, 160 nm, 180 nm, 200 nm, 220 nm, 230 nm, 250 nm, etc.; the material pore size is 1.5 nm-2.5 nm, such as 1.5 nm, 1.8 nm, 2.0 nm, 2.3 nm, 2.5 nm, etc.
[0008] In one embodiment of the present invention, the divalent metal ion includes Fe²⁺. + Co² + Ni² + Cu² + Zn² + One of them; the trivalent metal ions include Fe³⁺. + Cr³ + Al³ + Ga³ + One of them; the anion that coordinates with the divalent and trivalent metal ions may include SO42-. 2- NO 3- Cl - CH3COO - One of them.
[0009] In one embodiment of the present invention, the electron-withdrawing functional group R is selected from at least one of carboxyl, nitro, and cyano groups; Secondly, the present invention provides a method for preparing the above-mentioned functionalized bimetallic phthalocyanine MOF material, comprising the following steps: Phthalocyanine ligands and metal salts are mixed in a solvent at a molar ratio of 4.1-4.2:1, preferably 4.1:1, 4.12:1, 4.14:1, 4.16:1, 4.18:1, or 4.2:1. The mixture is subjected to a solvothermal reaction for 1-3 hours, preferably 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours, at a microwave power of 700-900W, preferably 700W, 750W, 800W, 850W, or 900W, and a temperature of 130-150℃, preferably 130℃, 135℃, 140℃, 145℃, or 150℃. After the reaction is completed, the product is centrifuged, washed, and vacuum dried to obtain the functionalized bimetallic phthalocyanine MOF material. In one embodiment of the present invention, the metal salt comprises two metal salts with different valence states, and the molar ratio of the two metal salts with different valence states is 1:1.
[0010] In one embodiment of the present invention, the phthalocyanine ligand is selected from at least one of phthalic acid, tetranitrophthalic acid, tetracarboxylated phthalic acid, and tetracyanophthalate. In one embodiment of the present invention, the solvent is n-pentanol; In one embodiment of the present invention, the washing solvent is one or more of N,N-dimethylformamide, ethanol, and water; the vacuum drying temperature is 80-100℃, preferably 80℃, 85℃, 90℃, 95℃, 100℃, etc.; the solvothermal reaction is carried out at a microwave power of 700-900W, preferably 700W, 750W, 800W, 850W, 900W, etc.; a temperature of 130-150℃, preferably 130℃, 135℃, 140℃, 145℃, 150℃, etc., for 1-3 hours, preferably 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.
[0011] Thirdly, the present invention provides a separator modified with a functionalized bimetallic phthalocyanine MOF material, comprising a base film and a functional coating coated on the base film near the positive electrode surface, wherein the functional coating comprises the aforementioned functionalized bimetallic phthalocyanine MOF material.
[0012] In one embodiment of the present invention, the base film comprises one or more of polyolefins, polyvinylidene fluoride, polyethylene oxide, polyvinyl chloride, polytetrafluoroethylene, polyacrylonitrile, polymethyl methacrylate, polyimide, cellulose, and polyurethane.
[0013] In one embodiment of the present invention, the thickness of the base film is 8-10 μm, preferably 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, etc.; the coating thickness of the functionalized bimetallic phthalocyanine MOF material is 1.5-2.5 μm, preferably 1.5 μm, 2.0 μm, 2.5 μm, etc.; the coating temperature is 80-100℃, preferably 80℃, 85℃, 90℃, 95℃, 100℃, etc.
[0014] Fourthly, the present invention provides a method for preparing the above-mentioned functionalized bimetallic phthalocyanine MOF-modified separator, comprising the following steps: Functionalized bimetallic phthalocyanine MOF material powder, binder, dispersant, and solvent (such as N-methylpyrrolidone) are mixed and vacuum stirred to form a homogeneous slurry; The slurry is coated onto the surface of the base film near the positive electrode. The base film coated with slurry is dried at a certain temperature (e.g., 90°C) to obtain the modified diaphragm.
[0015] In one embodiment of the present invention, the weight ratio of the functionalized bimetallic phthalocyanine MOF material powder, binder, and dispersant is (86-94): (3-7): (3-7).
[0016] In one embodiment of the present invention, the binder is polyvinylidene fluoride and the dispersant is polyvinylpyrrolidone.
[0017] Fifthly, the present invention provides a battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator located between the positive and negative electrodes, wherein the separator is a separator modified with the functionalized bimetallic phthalocyanine MOF material described above.
[0018] In one embodiment of the present invention, the active material of the positive electrode is selected from one or more of lithium iron phosphate, lithium manganese iron phosphate, and lithium-rich manganese-based materials.
[0019] Compared with existing technologies, the present invention has the following beneficial technical effects: This invention provides a functionalized bimetallic phthalocyanine MOF material, a preparation method, a modified separator, and a battery, which have the following advantages: This invention proposes using a single material (functionalized bimetallic phthalocyanine MOF material) to simultaneously address two key hazardous factors in lithium-ion batteries: trace amounts of water and dissolved metal ions. Electron-withdrawing functional groups (such as -COOH, -NO2) grafted onto the phthalocyanine benzene ring can effectively anchor and adsorb H+ ions ionized from trace amounts of water through a strong electric field. + This inhibits the hydrolysis of LiPF6 to generate HF at the source, reducing the attack of HF on the positive electrode and fundamentally slowing down metal dissolution. Simultaneously, the porous structure and metal centers of the functionalized bimetallic phthalocyanine MOF material can effectively physically adsorb and chemically coordinate the dissolved metal ions, preventing their migration to the negative electrode. This synergistic mechanism combining prevention and treatment achieves complete blocking of the side reaction chain. In this invention, by introducing bimetallic centers, the electron distribution of the functionalized bimetallic phthalocyanine MOF material is adjusted, which not only improves its conductivity but, more importantly, significantly enhances the structural stability of the material under high-temperature battery conditions, thus preventing functional failure. The morphology of the nanosheets allows them to be uniformly dispersed in the coating without affecting the basic performance of the separator. In this invention, the functionalized bimetallic phthalocyanine MOF material is synthesized using a rapid and efficient microwave solvothermal method, which is easy to prepare in batches. The separator modification employs a conventional slurry coating process, requiring only the addition of a specific proportion of the functionalized bimetallic phthalocyanine MOF material to the existing separator coating formulation. No additional complex equipment or steps are needed, making it highly compatible with existing battery separator production lines and demonstrating significant industrialization potential. Significant Results: Experimental data shows that, compared to cells using commercially available separators, cells employing the separator modified by this invention exhibit approximately 37% improved cycle life at high temperatures (60°C). Even under harsh conditions with excessive water content (e.g., 800 ppm), its cycle life remains comparable to that of normal cells using qualified separators, and it effectively maintains extremely low levels of negative electrode metal deposition, demonstrating its superior overall protection capabilities. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure of a functionalized bimetallic phthalocyanine MOF material provided by the present invention. Detailed Implementation
[0021] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.
[0022] Example 1 Tetracarboxylated phthalic acid (or pyromellitic dianhydride) was weighed as the phthalocyanine ligand, and aluminum trichloride and copper chloride were weighed as the metal salts. The total molar ratio of ligand to metal salt was controlled at 4.1:1, where Al³⁺ + With Cu² + The molar ratio was 1:1. The above raw materials were dissolved together in n-pentanol solvent and stirred thoroughly until a homogeneous mixture was formed. The mixture was transferred to a microwave reactor, and the microwave power was set to 800W, the reaction temperature to 140℃, and the reaction time to 2 hours for a solvothermal reaction. After the reaction, the mixture was allowed to cool naturally to room temperature. The reaction product was centrifuged and washed three times each with N,N-dimethylformamide and anhydrous ethanol to remove unreacted impurities and solvent. The washed solid product was placed in a vacuum drying oven and dried at 90℃ for 12 hours to obtain a tetracarboxylated functionalized phthalocyanine aluminum copper bimetallic MOF material.
[0023] The prepared tetracarboxylated phthalocyanine aluminum copper bimetallic MOF nanosheet powder, binder (polyvinylidene fluoride), and dispersant (polyvinylpyrrolidone) were dissolved in N-methylpyrrolidone solvent at a weight ratio of 90:5:5 and stirred thoroughly to obtain a slurry. The slurry was coated onto the side of a commercial PE membrane near the positive electrode using a roller coating process and dried at 90°C to obtain a tetracarboxylated functionalized phthalocyanine bimetallic MOF material modified membrane. Example 2 The preparation steps are exactly the same as in Example 1, except that the functionalized bimetallic phthalocyanine ligand is replaced with tetranitrophthalic acid, and finally a tetranitrofunctionalized phthalocyanine bimetallic MOF material modified membrane is obtained. Example 3 The preparation steps were exactly the same as in Example 1, resulting in a tetracarboxylic acid functionalized phthalocyanine bimetallic MOF material modified separator; the difference from Example 1 was the water content of the battery cell (the specific water content is shown in Table 2 below). Example 4 The preparation steps were exactly the same as in Example 2, and the final result was a tetranitro-functionalized phthalocyanine bimetallic MOF material modified separator. The difference from Example 2 was the water content of the battery cell (the specific water content is shown in Table 2 below). Example 5 The preparation steps were exactly the same as in Examples 1 and 3, resulting in a tetracarboxylic acid functionalized phthalocyanine bimetallic MOF material modified separator; the difference from Examples 1 and 3 was the water content of the battery cell (the specific water content is shown in Table 2 below). Example 6 The preparation steps were exactly the same as in Examples 2 and 4, and the final product was a tetranitro-functionalized phthalocyanine bimetallic MOF material modified membrane. The difference from Examples 2 and 4 was the water content of the battery cell (the specific water content is shown in Table 2 below). Comparative Example 1 The preparation steps are basically the same as in Example 1, the key difference being that the ligand is replaced with phthalonitrile (or other unsubstituted phthalocyanine synthesis precursors), and finally a phthalocyanine aluminum copper bimetallic MOF membrane without electron-withdrawing functional groups on the benzene ring is obtained; furthermore, Comparative Example 1 is subjected to baking treatment to control the water content of the membrane.
[0024] Comparative Example 2 The preparation steps were basically the same as those of Comparative Example 1. The key difference was that only copper chloride was used as the sole metal salt, and aluminum trichloride was not added. Finally, a copper aluminum phthalocyanine monometallic MOF membrane without electron-withdrawing functional groups on the benzene ring was obtained. Comparative Example 3 The preparation steps were basically the same as those in Comparative Example 1, and a copper aluminum phthalocyanine bimetallic MOF membrane without electron-withdrawing functional groups on the benzene ring was finally obtained. The difference from Comparative Example 1 was the water content of the battery cell (the specific water content is shown in Table 2 below). Comparative Example 4 The preparation steps are basically the same as those of Comparative Example 2. The key difference is that only copper chloride is used as the sole metal salt, and aluminum trichloride is not added. The final product is a copper aluminum phthalocyanine monometallic MOF membrane without electron-withdrawing functional groups on the benzene ring. The difference from Comparative Example 2 is that the water content of the battery cell is different (the specific water content is shown in Table 2 below). Comparative Example 5 Commercially available PE membranes without any coating treatment; moisture content of the membrane is controlled through baking treatment; Comparative Example 6 The same commercial PE separator as Comparative Example 5 without any coating treatment was used, but the water content of the battery cell was different (the specific water content is shown in Table 2 below). Comparative Example 7 The same commercial PE separator as Comparative Example 5 without any coating treatment was used. The difference between Comparative Examples 5 and 6 is the water content of the battery cells (the specific water content is shown in Table 2 below). Comparative Example 8 The same commercially available PE separator as Comparative Example 5, without any coating treatment; in this comparative example, the moisture content of the battery cell was not treated.
[0025] Preparation of positive electrode sheet: The active material lithium iron phosphate, the conductive agent multi-walled carbon nanotubes, and the binder polyvinylidene fluoride (PVDF) are mixed with the solvent N-methylpyrrolidone in a weight ratio of 97:1:2 to obtain a slurry with a solid content of 60%. The slurry is coated on the current collector Al foil, dried, rolled, and die-cut to obtain the positive electrode sheet of lithium ions. Negative electrode preparation: Artificial graphite (active material), acetylene black (conductive agent), styrene-butadiene rubber (SBR) (binder), sodium carboxymethyl cellulose (CMC) (thickener) are mixed with deionized water (solvent) in a weight ratio of 95:2:2:1 to obtain a slurry with a solid content of 50%. The slurry is coated onto carbon-coated Cu foil (current collector), dried, rolled, and die-cut to obtain the negative electrode of lithium-ion battery. Electrolyte preparation: The electrolyte adopts a conventional electrolyte formula, in which 1M LiFP6 is dispersed in an organic solvent (ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) = 1:1:1) to obtain the electrolyte. 2% by weight of vinylene carbonate (VC) is added to the electrolyte as an additive. The positive electrode, separator, and negative electrode are arranged in sequence and stacked to obtain a soft-pack electrode core. The electrode core is placed in an aluminum-plastic film and then subjected to baking, liquid injection, wetting, formation, venting, and capacity testing to obtain a soft-pack battery. Batteries with different moisture contents are obtained by controlling different baking times during the baking stage (24 hours for moisture content less than 200 ppm, 16 hours for moisture content of 500 ppm, and 4 hours for moisture content of 800 ppm). The standard for battery baking is that the water content of the electrode core is less than 200 ppm.
[0026] The basic physicochemical properties of the membrane, cell, and battery were tested: Among them, the resistivity of the diaphragm was measured: the resistivity of conventional diaphragms and diaphragms containing functionalized bimetallic phthalocyanine MOF materials was measured using an FT-341 four-probe resistivity meter to evaluate the influence of functionalized bimetallic phthalocyanine MOF materials on the performance of the diaphragm itself. The diaphragm sample was gently placed on the sample stage, the probe was controlled to contact the sample surface, a specific current and voltage were input, and its resistivity was measured. The measurement was repeated three times and the average value was taken to reduce experimental error. Measurement of cathode metal dissolution level: By disassembling the initial cell and the cell cycled to a specific state, powder was scraped from the negative electrode sheet and inductively coupled plasma emission spectroscopy (ICP) was performed to evaluate the improvement level of cathode metal dissolution after using the modified separator; Moisture content measurement in battery cells: The residual level of original moisture in the battery cells was measured using a Mettler Toledo (C30S) Karl Fischer moisture analyzer with the coulomb method. High-temperature battery cycling test: At 60°C, the batteries of the examples and comparative examples were subjected to 1C charge-discharge equal ratio cycling, with a voltage range of 2.5V-3.75V, until the cell reached 80% SOH (i.e., the battery discharge capacity was 80% of the initial capacity). The battery capacity was calibrated before the start of the cycle and after every 100 cycles. The capacity calibration was performed at 25°C using 0.33C charge-discharge cycle for three cycles, and the average value was taken as the calibrated capacity. Battery DCIR test: At 25°C, the batteries in the examples and comparative examples were adjusted to SOC of 50% using a current of 0.33C. After standing for 5 minutes, the standing voltage V1 was read. The batteries were discharged at 2C for 30 seconds, and the voltage V2 was read. DCIR = (V1-V2) / 2I. The experimental data obtained are shown in Table 1-3 below.
[0027] Table 1 shows the resistivity of the membranes prepared in Examples 1-2 and Comparative Examples 1, 2, and 5.
[0028] Table 2 shows the performance of the pouch cells prepared in Examples 1-6 and Comparative Examples 1-7 (cycled at 60°C to 80% SOH).
[0029] Table 3 shows the Fe content (ICP test) of the negative electrode of the batteries prepared in Examples 1-6 and Comparative Examples 1-8 after cycling. Examples 1 to 6 and Comparative Examples 1-7 are experimental data after the batteries were tested to 80% SOH according to the high temperature cycling test scheme, while Comparative Example 8 is a fresh cell after capacity testing, without any cycling test.
[0030]
[0031] Based on the test results of the examples and comparative examples, referring to Table 1, it can be seen that in Examples 1 and 2, compared to Comparative Example 5, the resistivity of the separator only slightly deteriorated. However, the resistivity of Comparative Example 1 (without functionalization) and Comparative Example 2 (without functionalization and single metal) significantly increased compared to Comparative Example 5, indicating that the modification with functionalized bimetallic MOF material does not affect the electrical performance of the separator itself. Referring to the test results in Table 2, in Examples 1 and 2, compared to Comparative Example 5, the battery DCR was basically the same, but the high-temperature cycle life was significantly improved, increasing by about 37%. This is mainly because the functionalized bimetallic phthalocyanine MOF material can effectively improve the dissolution of the positive electrode metal under high-temperature conditions, preventing its metal ions from reaching the negative electrode and causing side reactions, thus leading to capacity decay. In Comparative Examples 1 and 2, compared to Comparative Example 5, the improvement in high-temperature cycle life was within 15%. Compared with Comparative Examples 1 and 2, the high-temperature life of the battery in Examples 1 and 2 increased sequentially, indicating that the separator containing functionalized bimetallic phthalocyanine MOF material greatly improved the high-temperature life of the battery. (The text then abruptly shifts to a different topic: comparing different water contents.) The batteries in Examples 3-6 showed significantly improved high-temperature cycle life compared to Comparative Examples 6 and 7 under the same conditions. This is mainly attributed to the electron-withdrawing groups around the functionalized phthalocyanine benzene ring, which effectively absorb trace amounts of water in the electrode core, preventing subsequent side reactions. Test results show that even with a water content of 800 ppm, the cells using the modified separator (Examples 5 and 6) still had the same cycle life as the cell with completely acceptable water content (Comparative Example 5). Referring to Table 3, under the same water conditions, the iron content in the negative electrode of Examples 1 and 2 only slightly increased compared to the fresh cell (Comparative Example 8), while the iron content in the negative electrode of Comparative Examples 5 and 8 significantly increased before and after cycling. This indicates that the modified separator effectively improves the dissolution of metals from the positive electrode. Furthermore, comparisons of Examples 5 and 6, Comparative Examples 3 and 4, and Comparative Examples 7 and 8 reveal that even with high water content in the battery, the modified separator maintains a low level of metal dissolution. This is mainly because the electron-withdrawing groups grafted onto the phthalocyanine benzene ring effectively adsorb H2 produced by the ionization of trace amounts of water in the electrolyte. + Ions, thereby improving the occurrence of side reactions from the source.
[0032] That is, as shown in Table 1, the resistivity of the modified separator of the present invention is only slightly increased compared to the commercial separator, indicating that the modification layer has little effect on ion conduction performance. As shown in Table 2, under the same low moisture conditions, the cycle life of the battery of Example 1 of the present invention (1135 cycles) is significantly higher than that of Comparative Example 5 (825 cycles), an improvement of about 37.6%. Even under moisture conditions as high as 800 ppm, the cycle life of Example 5 (1099 cycles) is still much higher than that of Comparative Example 7 (560 cycles), and comparable to that of Comparative Example 5 with low moisture, proving the excellent moisture tolerance and life-enhancing effect of the separator of the present invention. As shown in Table 3, after cycling, the amount of iron deposited on the negative electrode of the battery using the modified separator of the present invention (Examples 1 and 5) is much lower than that of the comparative examples (Comparative Examples 5 and 7) using ordinary separators, and the increase is also less compared to the cell that has not undergone cycle testing (Comparative Example 8). This indicates that the separator of the present invention can effectively adsorb and fix metal ions dissolved from the positive electrode, preventing them from depositing on the negative electrode and causing side reactions. The effect is even more pronounced under high moisture conditions.
[0033] In summary, coating commercially available separators with functionalized bimetallic phthalocyanine MOF materials effectively improves the high-temperature cycle life of lithium-ion batteries. The main mechanism of action is through the adsorption of H+ ions from trace amounts of residual water in the electrolyte by the separator modification layer. + This avoids the reaction between trace amounts of water and electrolyte, which could lead to the dissolution of the positive electrode metal. At the same time, the trace amounts of dissolved metal can be well adsorbed by the coating layer, preventing them from migrating to the negative electrode and causing side reactions and capacity decay. Therefore, this invention effectively improves the high-temperature cycle life of the battery.
[0034] The above description is merely 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 functionalized bimetallic phthalocyanine MOF material, characterized in that, The functionalized bimetallic phthalocyanine MOF material has two metal ions, M, with different valence states at its center. n+ The functionalized bimetallic phthalocyanine MOF material has an electron-withdrawing functional group R grafted onto the peripheral benzene ring of the phthalocyanine ligand, and the two metal ions with different valence states include divalent metal ions and trivalent metal ions.
2. The functionalized bimetallic phthalocyanine MOF material according to claim 1, characterized in that, The functionalized bimetallic phthalocyanine MOF material has the morphology of nanosheets with an average size of 150-250 nm and a pore size of 1.5 nm-2.5 nm.
3. The functionalized bimetallic phthalocyanine MOF material according to claim 3, characterized in that, The divalent metal ions include Fe²⁺. + Co² + Ni² + Cu² + Zn² + One of them; the trivalent metal ions include Fe³⁺. + Cr³ + Al³ + Ga³ + One of them.
4. The functionalized bimetallic phthalocyanine MOF material according to claim 1, characterized in that, The electron-withdrawing functional group R is selected from at least one of carboxyl, nitro, and cyano groups.
5. A method for preparing a functionalized bimetallic phthalocyanine MOF material according to any one of claims 1 to 4, characterized in that, Includes the following steps: Phthalocyanine ligands and metal salts were mixed in a solvent at a molar ratio of 4.1-4.2:1 and subjected to a solvothermal reaction. After the reaction was completed, the product was centrifuged, washed and dried to obtain the functionalized bimetallic phthalocyanine MOF material. The metal salt includes two metal salts with different valence states, and the molar ratio of the two metal salts with different valence states is 1:
1.
6. The preparation method according to claim 5, characterized in that, The phthalocyanine ligand is selected from at least one of phthalic acid, tetranitrophthalic acid, tetracarboxylated phthalic acid, and tetracyanophthalic acid ester; the solvent is n-pentanol; the washing solvent is one or more of N,N-dimethylformamide, ethanol, and water; the vacuum drying temperature is 80-100℃; the solvothermal reaction is carried out at a microwave power of 700-900W and a temperature of 130-150℃ for 1-3 hours.
7. A diaphragm modified with a functionalized bimetallic phthalocyanine MOF material, characterized in that, It includes a base film and a functional coating applied to the base film near the positive electrode surface, wherein the functional coating comprises the functionalized bimetallic phthalocyanine MOF material according to any one of claims 1 to 4.
8. The modified diaphragm according to claim 7, characterized in that, The base film includes one or more of the following: polyolefin, polyvinylidene fluoride, polyethylene oxide, polyvinyl chloride, polytetrafluoroethylene, polyacrylonitrile, polymethyl methacrylate, polyimide, cellulose, and polyurethane.
9. The modified diaphragm according to claim 7, characterized in that, The thickness of the base film is 8-10 μm; the coating thickness of the functionalized bimetallic phthalocyanine MOF material is 1.5-2.5 μm; and the coating temperature is 80-100℃.
10. A method for preparing a functionalized bimetallic phthalocyanine MOF material-modified separator according to any one of claims 7 to 9, characterized in that, Includes the following steps: Functionalized bimetallic phthalocyanine MOF material powder, binder, dispersant, and solvent are mixed to form a homogeneous slurry; The slurry is coated onto the surface of the base film near the positive electrode. The base film coated with slurry is dried to obtain the modified diaphragm.
11. The preparation method according to claim 10, characterized in that, The weight ratio of the functionalized bimetallic phthalocyanine MOF material powder, binder, and dispersant is (86-94): (3-7): (3-7); preferably, the binder is polyvinylidene fluoride, the dispersant is polyvinylpyrrolidone, and the drying temperature is 80-100℃.
12. A battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator located between the positive and negative electrodes, characterized in that, The diaphragm is a diaphragm modified with the functionalized bimetallic phthalocyanine MOF material as described in any one of claims 7 to 9.
13. The battery according to claim 12, characterized in that, The active material of the positive electrode is selected from one or more of lithium iron phosphate, lithium manganese iron phosphate, and lithium-rich manganese-based materials.