Modified lithium lanthanum zirconium oxide material, preparation method thereof and lithium battery diaphragm
By forming a porous passivation layer and polymer coating on the surface of lithium lanthanum zirconium oxide material, the problem of residual alkali formation on the surface of lithium lanthanum zirconium oxide material was solved, achieving high ionic conductivity and stability, and improving the electrical performance and cycle life of the battery.
Patent Information
- Application Number
- CN202511398042.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-28
- Publication Date
- 2026-01-30
AI Technical Summary
The surface of lithium lanthanum zirconium oxide materials is prone to react with H2O and CO2 to generate residual alkali, which leads to a decrease in ionic conductivity and poor slurry stability, thus affecting electrical performance.
A porous passivation layer composed of lithium-ionized porous materials is formed on the surface of lithium lanthanum zirconium oxide materials, and a polymer is coated on its surface to suppress the formation of residual alkali through ion adsorption and moisture isolation.
This improves the stability and ionic conductivity of lithium lanthanum zirconium oxide materials, reduces internal resistance, and enhances battery cycle life and electrical performance.
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery materials technology, and in particular to a modified lithium lanthanum zirconium oxide material and its preparation method, as well as a lithium battery separator. Background Technology
[0002] Lithium lanthanum zirconium oxide (LLZO) has high ionic conductivity (approximately 10⁻⁶ Ω·cm at room temperature). -4 ~10 -3 With its high conductivity (S / cm), high electrochemical stability, and good chemical stability to both cathode materials and lithium metal anodes, LLZO is considered an ideal material for next-generation high-energy-density lithium batteries. Compared to traditional separator coating materials, such as alumina, LLZO has higher ionic conductivity, which can reduce internal resistance and suppress lithium dendrite formation, thus making it a promising candidate for high-energy-density lithium battery separator coatings. However, the LLZO surface readily reacts with H2O and CO2 to generate residual alkali. This not only reduces the effective content and significantly decreases ionic conductivity, but also leads to poor slurry stability and affects the uniformity of the coating formed when using aqueous slurry preparation processes, ultimately resulting in degraded electrical performance. Summary of the Invention
[0003] Based on the technical problems existing in the background technology, the present invention proposes a modified lithium lanthanum zirconium oxide material and its preparation method, as well as a lithium battery separator.
[0004] The present invention proposes a method for preparing modified lithium lanthanum zirconium oxide materials, comprising the following steps:
[0005] S1. Lithium lanthanum zirconium oxide powder and porous material are added to deionized water and stirred to react, thereby obtaining lithium lanthanum zirconium oxide material coated with lithium porous material. The mass ratio of lithium lanthanum zirconium oxide powder to porous material is 10:0.5~2, and the porous material is at least one of molecular sieve and MOF material.
[0006] S2. The lithium lanthanum zirconium oxide material coated with the lithium-ionized porous material and the organic polymer are added to an organic solvent and stirred to react, thereby obtaining a modified lithium lanthanum zirconium oxide material. The mass ratio of the lithium lanthanum zirconium oxide material coated with the lithium-ionized porous material to the organic polymer is 10:0.5~2.
[0007] Lithium lanthanum zirconium oxide (LLANZO) can undergo ion adsorption with molecular sieves and exhibit van der Waals forces with MOF (metal-organic framework) materials. This invention reacts LLANZO with the aforementioned molecular sieves or MOF-type porous materials, causing the porous material to coat the surface of the LLANZO. Simultaneously, residual alkali on the LLANZO surface is adsorbed, forming a porous passivation layer composed of lithium-modified porous material. Then, a polymer is coated onto this passivation layer to fill any uncoated areas, effectively isolating moisture and enhancing the stability of the LLANZO. The modified LLANZO material obtained by this invention can be used for aqueous slurry coating of separators. It effectively isolates moisture during separator preparation, inhibits residual alkali formation, and utilizes the adsorption of residual alkali by the porous passivation layer to mitigate the adverse effects of residual alkali on separator performance. This effectively leverages the high ionic conductivity of LLANZO, reducing internal resistance and improving battery cycle life.
[0008] Preferably, the particle size D50 of the lithium lanthanum zirconium oxide powder is 0.2µm to 1.5µm, and the particle size D50 of the porous material is 100nm to 600nm. By controlling the appropriate particle size of the lithium lanthanum zirconium oxide powder and the porous material, the porous passivation layer on the surface of the lithium lanthanum zirconium oxide powder can have a suitable thickness, thereby giving the separator appropriate air permeability and enabling the battery to have high capacity and low internal resistance.
[0009] Preferably, the weight-average molecular weight (Mw) of the organic polymer is between 20,000 and 700,000, for example, it can be 20,000, 50,000, 100,000, 200,000, 500,000, or 700,000. By controlling the molecular weight of the organic polymer, the stability of the lithium lanthanum zirconium oxide membrane can be improved while ensuring appropriate air permeability, thereby further enhancing the stability of the battery.
[0010] In this invention, the specific types of porous molecular sieves and MOF materials are conventionally selected. Preferably, the porous material is selected from at least one of aluminosilicate molecular sieves, ZIF-8 material, UIO-66 material, and ZIF-67 material.
[0011] In this invention, the organic polymer may be selected from at least one of the following: an organic polymer with adhesive properties or an organic polymer that can form coordinate bonds with metal ions. For example, the organic polymer with adhesive properties may be polydopamine, polyvinylidene fluoride, or polymethyl methacrylate. For example, the organic polymer that can form coordinate bonds with metal ions may be polyacrylonitrile or ethyl polycyanoacrylate.
[0012] In this invention, the organic solvent is a conventional choice; any organic solvent capable of dissolving the organic polymer can be selected. Preferably, the organic solvent is selected from at least one of ethanol, isopropanol, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.
[0013] Preferably, in step S1, the temperature of the stirring reaction is 50~70℃, and the time is 10~24h. By controlling the temperature and time of the stirring reaction in step S1, the porous passivation layer formed on the lithium lanthanum zirconium oxide surface can be made more uniform, further improving the stability of the separator.
[0014] In S1, after the reaction is complete, conventional post-processing steps may be included, such as solid-liquid separation, washing and drying of the obtained solid.
[0015] Preferably, in step S2, the stirring reaction temperature is 25~35℃, and the time is 2~8h. By controlling the temperature and time of the stirring reaction in step S2, the formed organic polymer coating layer can be made more uniform, thereby further improving the stability of the diaphragm.
[0016] In S2, after the reaction is complete, conventional post-processing steps may be included, such as solid-liquid separation, washing and drying of the obtained solid.
[0017] This invention also proposes a modified lithium lanthanum zirconium oxide material, which is prepared by the aforementioned method.
[0018] The present invention also proposes a lithium battery separator, comprising a base film, wherein at least one side of the base film has a coating; the raw materials of the coating include the modified lithium lanthanum zirconium oxide material, a dispersant, and a binder.
[0019] In the lithium battery separator of this invention, the raw material ratio of the coating is a conventional selection, which can be adjusted according to actual needs. Preferably, the mass ratio of the modified lithium lanthanum zirconium oxide material, dispersant, and binder is 1:0.02~0.8:0.01~0.5.
[0020] The dispersant and binder in the above coating materials are conventional choices.
[0021] Preferably, the dispersant is selected from at least one of polyacrylamide, waterborne polyurethane resin, and polyvinyl alcohol.
[0022] Preferably, the adhesive is selected from polyacrylic acid, polyacrylate, and polyethersulfone.
[0023] In the lithium battery separator of this invention, the coating thickness is a conventional selection and can be adjusted according to actual needs. Preferably, the coating thickness is 1~6µm.
[0024] Preferably, the coating is formed by curing a coating slurry, which is obtained by adding deionized water to the raw materials of the coating and then mixing the slurry. Using deionized water as the solvent for mixing the coating slurry has the advantages of being safe, environmentally friendly, and low-cost.
[0025] Preferably, the base film is selected from PE base film, PP base film or PE / PP composite base film.
[0026] Preferably, the method for preparing the lithium battery separator includes: adding deionized water to the raw materials of the coating, then mixing them into a slurry to obtain a coating slurry; coating the coating slurry onto a base film, and curing it to form a coating to obtain a lithium battery separator.
[0027] In this invention, coating can be performed using conventional methods, such as scraping, dipping, or spraying; curing can be performed using conventional methods, such as drying; preferably, the drying temperature is 50~80°C.
[0028] The beneficial effects of this invention are as follows:
[0029] This invention involves reacting lithium lanthanum zirconium oxide with a porous material to form a porous passivation layer on the surface of the lithium lanthanum zirconium oxide, composed of the lithium-ionized porous material. A polymer is then coated onto this passivation layer to obtain a modified lithium lanthanum zirconium oxide material. The modified lithium lanthanum zirconium oxide material obtained by this invention can be used for aqueous slurry-coated separators, effectively leveraging the high ionic conductivity of lithium lanthanum zirconium oxide to reduce internal resistance and improve battery cycle life. Detailed Implementation
[0030] The technical solution of the present invention will now be described in detail through specific embodiments.
[0031] Example 1
[0032] Preparation of modified lithium lanthanum zirconium oxide materials:
[0033] S1. 10g of lithium lanthanum zirconium oxide powder with a particle size D50 of 0.6μm and 1.2g of aluminosilicate molecular sieve with a D50 of 200nm were added to 20g of deionized water and stirred at 60℃ for 12h. After the reaction was completed, the mixture was centrifuged, the resulting solid was washed with deionized water, and then dried in a vacuum oven at 80℃ to obtain lithium lanthanum zirconium oxide material coated with lithium molecular sieve.
[0034] S2. Add 8g of lithium lanthanum zirconium oxide material coated with lithium molecular sieve and 1.05g of ethyl polycyanoacrylate (Mw=50,000) to N-methylpyrrolidone, and then stir and react at 30℃ for 3h. After the reaction is completed, centrifuge and dry the obtained solid under vacuum at 80℃ for 5h to obtain modified lithium lanthanum zirconium oxide material.
[0035] Preparation of lithium battery separator:
[0036] Weigh 6g of modified lithium lanthanum zirconium oxide material, 0.24g of dispersant polyacrylamide, and 0.12g of binder polyacrylic acid, add deionized water to form a slurry, and obtain a coating slurry; apply the coating slurry to one side of a 9µm PE base film, and dry it in an oven at 60℃ to obtain the final product.
[0037] Example 2
[0038] Preparation of modified lithium lanthanum zirconium oxide materials:
[0039] S1. 10g of lithium lanthanum zirconium oxide powder with a particle size D50 of 0.2μm and 0.5g of aluminosilicate molecular sieve with a D50 of 100nm were added to 20g of deionized water and stirred at 50℃ for 10h. After the reaction was completed, the mixture was centrifuged, and the resulting solid was washed with deionized water and then dried in a vacuum oven at 80℃ to obtain lithium lanthanum zirconium oxide material coated with lithium molecular sieve.
[0040] S2. Add 8g of lithium lanthanum zirconium oxide material coated with lithium molecular sieve and 0.4g of polymethyl methacrylate (Mw=100,000) to N-methylpyrrolidone, and then stir and react at 25°C for 2h. After the reaction is completed, centrifuge and dry the obtained solid under vacuum at 80°C for 4h to obtain modified lithium lanthanum zirconium oxide material.
[0041] The preparation method of the lithium battery separator is the same as in Example 1.
[0042] Example 3
[0043] Preparation of modified lithium lanthanum zirconium oxide materials:
[0044] S1. 10g of lithium lanthanum zirconium oxide powder with a particle size D50 of 1.5μm and 2g of ZIF-8 with a D50 of 600nm were added to 22g of deionized water and stirred at 70℃ for 24h. After the reaction was completed, the solid was centrifuged, washed with deionized water, and then dried in a vacuum oven at 80℃ to obtain lithium lanthanum zirconium oxide material coated with lithium ZIF-8.
[0045] S2. Add 8g of lithium lanthanum zirconium oxide material coated with lithium ZIF-8 and 1.6g of ethyl polycyanoacrylate (Mw=50,000) to N-methylpyrrolidone, and then stir and react at 35°C for 8h. After the reaction is completed, centrifuge and dry the obtained solid under vacuum at 80°C for 5h to obtain modified lithium lanthanum zirconium oxide material.
[0046] The preparation method of the lithium battery separator is the same as in Example 1.
[0047] Comparative Example 1
[0048] Preparation of lithium battery separator:
[0049] Weigh 6g of alumina powder with a D50 of 0.6μm, 0.24g of dispersant polyvinylamide, and 0.12g of binder polyacrylic acid, add deionized water to form a slurry, and obtain a coating slurry; apply the coating slurry to one side of a 9µm PE base film and dry it in an oven at 60℃ to obtain the final product.
[0050] Comparative Example 2
[0051] Preparation of lithium battery separator:
[0052] Weigh 6g of lithium lanthanum zirconium oxide powder with a D50 of 0.6μm, 0.24g of dispersant polyvinylamide, and 0.12g of binder polyacrylic acid, add deionized water to form a slurry, and obtain a coating slurry; apply the coating slurry to one side of a 9µm PE base film and dry it in an oven at 60℃ to obtain the final product.
[0053] Comparative Example 3
[0054] Preparation of lithium lanthanum zirconium oxide materials coated with lithium molecular sieves:
[0055] 10g of lithium lanthanum zirconium oxide powder with a particle size D50 of 0.6μm and 1.2g of aluminosilicate molecular sieve with a D50 of 200nm were added to 20g of deionized water and stirred at 60℃ for 12h. After the reaction was completed, the mixture was centrifuged, and the resulting solid was washed with deionized water and then dried in a vacuum oven at 80℃ to obtain lithium lanthanum zirconium oxide material coated with lithium molecular sieve.
[0056] Preparation of lithium battery separator:
[0057] Weigh 6g of lithium lanthanum zirconium oxide material coated with lithium molecular sieve, 0.24g of dispersant polyacrylamide, and 0.12g of binder polyacrylic acid, add deionized water to form a slurry, and obtain a coating slurry; apply the coating slurry to one side of a 9µm PE base film and dry it in an oven at 60℃ to obtain the final product.
[0058] Comparative Example 4
[0059] Preparation of organic polymer-coated lithium lanthanum zirconium oxide materials:
[0060] Eight g of lithium lanthanum zirconium oxide powder with a particle size D50 of 0.6 μm and 1.05 g of ethyl polycyanoacrylate (Mw=50,000) were added to N-methylpyrrolidone. The mixture was then stirred at 30 °C for 3 h. After the reaction was completed, the mixture was centrifuged and the resulting solid was vacuum dried at 80 °C for 5 h to obtain an organic polymer-coated lithium lanthanum zirconium oxide material.
[0061] Preparation of lithium battery separator:
[0062] Weigh 6g of organic polymer-coated lithium lanthanum zirconium oxide material, 0.24g of dispersant polyacrylamide, and 0.12g of binder polyacrylic acid, add deionized water to form a slurry, and obtain a coating slurry; apply the coating slurry to one side of a 9µm PE base film, and dry it in an oven at 60℃ to obtain the final product.
[0063] In the preparation of lithium battery separators in Examples 1-3 and Comparative Examples 1-4, the solid content of the coating slurry and the coating amount of the scraping were the same.
[0064] Test case
[0065] The air permeability of the lithium battery separators prepared in the above embodiments and comparative examples was tested. The test steps were as follows: the separator was placed in the test head of a Gurley 4340 air permeability meter for air permeability testing, and the average value of the three test results was taken as the air permeability of the separator.
[0066] The test results are shown in Table 1.
[0067] The lithium battery separators prepared in the above embodiments and comparative examples were assembled into coin cells. The assembly method of the cells is as follows:
[0068] Preparation of positive electrode sheet: using ternary material LiNi 0.78 Co 0.10 Mn 0.12 O2, conductive agent Super-P (conductive carbon black), and binder polyvinylidene fluoride (PVDF) are mixed in N-methylpyrrolidone (NMP) at a mass ratio of 95:3:2 to obtain a positive electrode slurry. The positive electrode slurry is coated on aluminum foil, vacuum dried at 110°C for 24 hours, and then cut into positive electrode sheets using a slicing machine.
[0069] Preparation of negative electrode sheet: Graphite, conductive agent Super-Li, thickener sodium carboxymethyl cellulose (CMC), binder styrene-butadiene rubber latex (SBR) are mixed in a ratio of 94.5:1:2.25:2.25, and the weight ratio of water to solids is 64:56.7 to obtain negative electrode slurry. The negative electrode slurry is coated on copper foil and baked at 80℃ for 6 hours. The negative electrode sheet is then cut using a slicing machine.
[0070] Using the above-mentioned positive and negative electrode sheets, a 3Ah soft-pack battery was assembled with a separator. Charge-discharge DC internal resistance (DCR) and cycle performance were then tested. The test results are shown in Table 1. The test characterization methods are as follows:
[0071] Charge-discharge DCR: (1) In an environment of 25±2℃, three batteries of each example and comparative example were tested for DCR. The batteries were fully charged at 1C constant current and constant voltage (4.25V, 0.05C), left to stand for 1h, and discharged at 1C constant current to 2.8V (1.8V at 0℃ and below). The discharge capacity at this temperature was recorded and used as the reference capacity Qt for the next pulse test; (2) The batteries were charged at 1C constant current and constant voltage (4.25V, 0.05C) at 25℃. (0.5C) After fully charging, let it rest for 1 hour, discharge at 1C constant current for 30 minutes to 50% SOC, the voltage after resting for 30 minutes is recorded as V0, discharge at 3Qt for 10 seconds is recorded as V1, rest for 40 seconds is recorded as V2, and then charge at 2.25Qt for 10 seconds is recorded as V3; (3) rest for 5 minutes, then discharge at 0.33C constant current with a voltage limit of 2.8V, charge at 0.33C constant current and constant voltage with a voltage limit of 3.6V and a current limit of 0.05C, rest for 5 minutes, and then end. The formula for calculating the discharge DCR of the battery is: (V0-V1) / 3Qt*1000, and the formula for calculating the charging DCR of the battery is: (V3-V2) / 2.25Qt*1000. Then calculate the average value of the three batteries.
[0072] Capacity retention of batteries after 100 cycles at room temperature: In an environment of 25±2℃, three batteries for each example and comparative example were cycle tested. The average capacity measured in the first 10 weeks was taken as the baseline capacity C0. At the same time, the discharge capacity of the battery after 100 cycles at room temperature was measured as C100. The capacity retention rate was calculated as C100 / C0, and then the average value of the three batteries was calculated.
[0073] Table 1
[0074] Group Thickness / µm Breathable / s / 100mL Capacity retention rate after 100 cycles at room temperature / % Discharge DCR / mΩ Charging DCR / mΩ Example 1 11.2 124 95.36 23.57 24.07 Example 2 11.5 123 95.22 23.62 24.12 Example 3 11.4 126 94.99 23.44 24.29 Comparative Example 1 11.2 129 88.41 25.65 27.56 Comparative Example 2 14.5 187 86.95 25.94 27.21 Comparative Example 3 13.6 142 89.18 25.52 26.69 Comparative Example 4 14.3 141 89.83 25.53 26.72
[0075] As shown in Table 1, the modified lithium lanthanum zirconium oxide material of the present invention can be used for aqueous slurry coating of separators. The resulting separators not only have suitable air permeability but also improve ionic conductivity and stability, thereby effectively improving the cycle performance and reducing internal resistance of the battery. Comparative Example 1 uses alumina as the separator coating material, resulting in high internal resistance and poor cycle performance. Comparative Example 2 uses unmodified lithium lanthanum zirconium oxide material as the separator coating material. Due to the large amount of residual lithium hydroxide generated, it is not only prone to agglomeration leading to increased coating thickness but also prone to pore blockage leading to increased air permeability, resulting in poor battery cycle performance and high internal resistance. Comparative Examples 3 and 4 use molecular sieve-coated modified lithium lanthanum zirconium oxide material and organic polymer-coated modified lithium lanthanum zirconium oxide material as separator coating materials, respectively. The inhibition effect of residual alkali is not ideal, resulting in still high air permeability of the separator and no significant improvement in battery cycle performance and internal resistance.
[0076] 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 method for producing a modified lithium lanthanum zirconium oxide material, characterized by, Comprising the following steps: S1, adding lithium lanthanum zirconium oxide powder and porous material into deionized water, stirring and reacting to obtain lithiumized porous material coated lithium lanthanum zirconium oxide material, the mass ratio of lithium lanthanum zirconium oxide powder and porous material is 10:0.5~2, and the porous material is at least one of molecular sieve, MOF material; S2, adding the lithiumized porous material coated lithium lanthanum zirconium oxide material and organic polymer into organic solvent, stirring and reacting to obtain modified lithium lanthanum zirconium oxide material, the mass ratio of lithiumized porous material coated lithium lanthanum zirconium oxide material and organic polymer is 10:0.5~2.
2. The method for producing a modified lithium lanthanum zirconium oxygen material according to claim 1, characterized by, The particle size D50 of the lithium lanthanum zirconium oxide powder is 0.2µm~1.5µm, and the particle size D50 of the porous material is 100nm~600nm.
3. The method of making a modified lithium lanthanum zirconium oxide material of claim 1, wherein, The weight average molecular weight Mw of the organic polymer is 20,000~700,000.
4. The method of making a modified lithium lanthanum zirconium oxide material of claim 1, wherein, The porous material is at least one of silicoaluminate molecular sieve, ZIF-8 material, UIO-66 material, and ZIF-67 material; and the organic polymer is at least one of polyacrylonitrile, polyvinyl cyanoacetate, polydopamine, polyvinylidene fluoride, and polymethyl methacrylate.
5. The method of making a modified lithium lanthanum zirconium oxide material of claim 1, wherein, In S1, the temperature of stirring and reaction is 50~70℃, and the time is 10~24h.
6. The method of making a modified lithium lanthanum zirconium oxide material of claim 1, wherein, In S2, the temperature of stirring and reaction is 25~35℃, and the time is 2~8h.
7. A modified lithium lanthanum zirconium oxide material characterized by, Prepared by the preparation method of any one of claims 1~6.
8. A lithium battery separator, characterized by, Comprising a base film, at least one side of the base film has a coating layer; the raw material of the coating layer comprises the modified lithium lanthanum zirconium oxide material of claim 7, a dispersant and a binder.
9. The lithium battery separator of claim 8, wherein, The mass ratio of the modified lithium lanthanum zirconium oxide material, the dispersant and the binder is 1:0.02~0.8:0.01~0.
5.
10. The lithium battery separator of claim 8, wherein, The coating layer is formed by curing the coating slurry, and the coating slurry is obtained by mixing the raw material of the coating layer with deionized water.