Water-based solid electrolyte coating diaphragm and preparation method thereof
Hydrogarnet-phase lithium lanthanum zirconium oxide was prepared by hydrothermal reaction and hydrophobic modification, which solved the problem of LiOH generation and pore blockage in traditional garnet-phase lithium lanthanum zirconium oxide in aqueous environment. This resulted in a highly efficient solid electrolyte coating membrane, improving the cycle performance and safety of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-09
- Publication Date
- 2026-04-03
AI Technical Summary
Traditional garnet-phase lithium lanthanum zirconium oxide generates a large amount of lithium hydroxide in an aqueous environment, which blocks the pores of the base film, leading to increased internal resistance and reduced ion transport efficiency in the battery.
Hydrogarnet-phase lithium lanthanum zirconium oxide was prepared by hydrothermal reaction and hydrophobically modified to reduce the amount of LiOH generated. Solid electrolyte coating membrane was then prepared in an all-aqueous process.
It effectively avoids the formation of LiOH, improves the cycle performance and safety of the battery, and achieves a separator coating with high mechanical strength, making it suitable for high energy density batteries.
Smart Images
Figure CN121790684A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of membrane preparation technology, specifically to aqueous solid electrolyte coated membranes and their preparation methods. Background Technology
[0002] Lithium-ion batteries dominate the consumer electronics, electric vehicle, and energy storage sectors due to their high energy density and long cycle life. However, commercial lithium-ion batteries generally use flammable organic liquid electrolytes, which pose safety risks such as thermal runaway, easy decomposition under high pressure, and poor compatibility with lithium metal anodes, severely restricting the development of high-energy-density battery systems (such as lithium metal batteries). Furthermore, to achieve even higher energy density targets, the exploration of novel battery systems (such as solid-state batteries) is urgently needed, but liquid electrolytes cannot meet the interface stability and safety requirements of solid-state batteries, necessitating the development of high-performance solid-state electrolyte materials.
[0003] Inorganic solid-state electrolytes are considered key to overcoming current bottlenecks due to their non-flammability, high mechanical strength, and wide electrochemical window. Among them, garnet-type lithium lanthanum zirconium oxide (Li7La3Zr2O) 12 LLZO) has both high lithium-ion conductivity (10) -4 The S / cm ratio and chemical stability to lithium metal have become research hotspots. However, in the process of preparing separators using aqueous coating processes, traditional garnet-phase LLZO will deteriorate in aqueous environments due to H... + -Li + The exchange reaction generates lithium hydroxide (LiOH). LiOH seeps into the micropores of the base membrane with water, and after drying, it blocks the pores, significantly increasing the internal resistance of the battery and reducing the ion transport efficiency. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides an aqueous solid electrolyte coating membrane and its preparation method, solving the technical problem that traditional garnet-phase lithium lanthanum zirconium oxide membranes generate a large amount of lithium hydroxide in an aqueous environment, clogging the pores of the base membrane.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] On one hand, the present invention provides a method for preparing an aqueous solid electrolyte coated membrane, comprising the following steps:
[0007] Hydrogarnet-phase lithium lanthanum zirconium oxide is prepared by hydrothermal reaction. The hydrogarnet-phase lithium lanthanum zirconium oxide is then hydrophobically modified to obtain hydrophobic hydrogarnet-phase lithium lanthanum zirconium oxide. The hydrophobic hydrogarnet-phase lithium lanthanum zirconium oxide, dispersant, binder, and water are mixed evenly to obtain a solid electrolyte coating slurry. The solid electrolyte coating slurry is coated onto a base film and dried to obtain an aqueous solid electrolyte coating membrane.
[0008] The above preparation method, which prepares hydrogarnet-phase lithium lanthanum zirconium oxide through hydrothermal reaction and performs hydrophobic modification on the hydrogarnet-phase lithium lanthanum zirconium oxide, can reduce the amount of LiOH generated during the preparation of aqueous solid electrolyte coating membrane using garnet-phase lithium lanthanum zirconium oxide. As a result, the gas permeability of the prepared solid electrolyte coating membrane is increased by <20s / 100cc, and the prepared battery has excellent cycle performance.
[0009] Preferably, the garnet-phase lithium lanthanum zirconium oxide is a garnet-phase Li x La3Zr2O 12-y (OH) y Where x + y = 7, 0.2 <x / y<1;
[0010] The hydrophobic garnet phase lithium lanthanum zirconium oxide has an ionic conductivity of 10. -6 ~10 -4 S / cm, particle size 50nm~10μm, surface contact angle >100°.
[0011] Preferably, the hydrothermal reaction is a hydrothermal reaction of garnet-phase lithium lanthanum zirconium oxide at 140–180°C for 4–24 hours to obtain garnet-phase lithium lanthanum zirconium oxide.
[0012] Preferably, the garnet phase lithium lanthanum zirconium oxide is hydrophobically modified using a silane coupling agent.
[0013] Preferably, the silane coupling agent is a silane coupling agent containing long-chain alkyl or fluoroalkyl groups;
[0014] The amount of the silane coupling agent is 1 to 5 wt% of the mass of the garnet phase lithium lanthanum zirconium oxide.
[0015] Preferably, the silane coupling agent containing long-chain alkyl groups is dodecyltriethoxysilane, and the silane coupling agent containing fluorinated alkyl groups is tridecafluorooctyltriethoxysilane.
[0016] The dispersant is selected from one or more of sodium polyacrylate, sodium alkyl sulfonate, or alkyl carboxylates.
[0017] Preferably, the adhesive is selected from one or more of polyvinylidene fluoride, styrene-butadiene rubber latex, or waterborne polyurethane.
[0018] Preferably, the method for preparing the aqueous solid electrolyte coated membrane satisfies at least one of the following conditions:
[0019] The base membrane is selected from polyethylene microporous membrane, polypropylene microporous membrane, polyethylene / polypropylene composite membrane or non-woven fabric membrane, and the thickness of the base membrane is 2-50 μm, and the porosity is 30-80%.
[0020] The solid electrolyte coating slurry is prepared by uniformly mixing 10-30 parts of hydrophobic garnet-phase lithium lanthanum zirconium oxide, 0.1-0.5 parts of dispersant, 1-5 parts of binder, and 70-100 parts of water to obtain the solid electrolyte coating slurry.
[0021] The solid electrolyte coating slurry is coated onto the base film by dip coating, microgravure coating or a combination thereof, and the wet film thickness of the solid electrolyte coating slurry is 5-15 μm.
[0022] In the solid electrolyte coating slurry, the particle size D of the hydrophobic garnet phase lithium lanthanum zirconium oxide is... 50 The size is 1–5 μm.
[0023] On the other hand, the present invention provides an aqueous solid electrolyte coating membrane prepared by the preparation method described in the first aspect, comprising:
[0024] Base membrane,
[0025] A solid electrolyte coating is located on at least one surface of the base film.
[0026] Preferably, the thickness of the solid electrolyte coating is 1–10 μm. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 This is a schematic diagram of the structure of the hydrophobic modified solid electrolyte powder prepared in Example 1;
[0029] Figure 2 These are the Raman spectra of garnet phase and hydrogarnet phase lithium lanthanum zirconium oxide in Example 1;
[0030] Figure 3 This is a scanning electron microscope image of the aqueous solid electrolyte coating membrane in Example 1. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] This application provides an aqueous solid electrolyte coated membrane and its preparation method, which solves the technical problem that traditional garnet phase LLZO generates a large amount of lithium hydroxide in an aqueous environment, blocking the pores of the base membrane.
[0033] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:
[0034] Inorganic solid-state electrolytes are considered key to overcoming current bottlenecks due to their non-flammability, high mechanical strength, and wide electrochemical window. Among them, garnet-type lithium lanthanum zirconium oxide (Li7La3Zr2O) 12 LLZO) has both high lithium-ion conductivity (10) -4 The S / cm ratio and chemical stability to lithium metal have become research hotspots. However, traditional garnet-phase LLZO will deteriorate in aqueous environments (such as in aqueous membrane coating processes) due to H... + -Li + The exchange reaction generates lithium hydroxide (LiOH), which leads to two major problems: 1. Deterioration of slurry performance: The highly alkaline environment of LiOH causes the cross-linking failure of binders (such as PVDF), damaging the coating structure; 2. Membrane pore blockage: LiOH seeps into the micropores of the base membrane with water, and after drying, it blocks the pores, significantly increasing the internal resistance of the battery and reducing the ion transport efficiency.
[0035] Existing technologies attempt to improve the stability of LLZO through doping or surface coating, but doping methods struggle to suppress Li. + Dissolution occurs, and the coating layer (such as Al2O3, Li3PO4) is difficult to scale up due to poor interfacial compatibility or complex processes (such as atomic layer deposition). Furthermore, to avoid the reaction between LLZO and water, existing technologies mostly rely on oil-based solvents (such as NMP) to prepare the slurry, resulting in high costs and environmental pollution. Therefore, developing a solid electrolyte material that combines water stability, process compatibility, and high ionic conductivity, and is compatible with environmentally friendly aqueous coating processes, has become a core issue that urgently needs to be addressed to promote the industrialization of high-safety, high-energy-density lithium batteries.
[0036] The present invention achieves the following beneficial effects:
[0037] 1. Hydrothermal replacement reduces Li + Unstable Li in hydrogarnet-phase LLZO prepared by hydrothermal method + H has been + The exchange and substitution process ensures that the reaction with water produces virtually no LiOH. This reduces the LiOH content by several orders of magnitude when preparing water-based slurries, effectively preventing cross-linking failure of additives (such as PVDF) and pore blockage in the coating in highly alkaline environments.
[0038] 2. Hydrophobic surface barrier: The LLZO surface modified with hydrophobic silane coupling forms a long-chain alkyl / fluoroalkyl layer, which repels water molecules and greatly improves the material's moisture resistance. Tests show that the modified LLZO coating can achieve a contact angle of over 100° (fluoroalkyl coupling agents can be used when the water contact angle is >130°), and it is difficult for LiOH to form even in high humidity environments.
[0039] 3. Compatible with aqueous processes: The hydrophobically modified LLZO phase used is stable and compatible with both water and air, allowing for slurry preparation without the need for organic solvents. The entire preparation process is entirely aqueous, avoiding the use of toxic solvents such as NMP, making it environmentally friendly.
[0040] 4. Improved Cycle Performance: The high-mechanical-strength solid electrolyte coating is uniformly distributed on the surface of the base film, which can suppress lithium dendrite puncture. The lithium battery cycle life based on the coating membrane of this invention is significantly improved. For example, the full cell can retain more than 90% of its capacity after 500 cycles at 1C rate, which is much higher than the unmodified comparative ratio (about 68%), demonstrating excellent dendrite suppression effect.
[0041] In summary, this invention provides a solid electrolyte coating membrane that combines internal and surface waterproofing. By employing a hydrothermal and hydrophobic composite modification strategy, it solves the fundamental defects of LLZO in the preparation of aqueous slurries, making it suitable for aqueous membrane coating in high-safety, high-energy-density batteries.
[0042] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.
[0043] I. Preparation Method
[0044] Example 1
[0045] This embodiment provides a method for preparing an aqueous solid electrolyte coated membrane, comprising the following steps:
[0046] S1, commercial garnet phase Li7La3Zr2O 12 20g of powder (purchased from Guangdong Boyue New Energy Technology Co., Ltd.) was added to 200mL of deionized water containing 0.2g of sodium polyacrylate dispersant, and placed in a 300mL autoclave. The mixture was then subjected to hydrothermal reaction at 160℃ for 12 hours. During the reaction, some H₂O was generated. + / Li + Exchange to obtain garnet phase Li x La3Zr2O 12-y (OH) y The powder (x+y≈7, x / y≈0.6) is weakly acidic, stable in water, and no longer forms soluble LiOH. Commercial garnet phase Li7La3Zr2O12 Powder, garnet phase Li x La3Zr2O 12-y (OH) y Raman spectra of powders are shown below. Figure 2 ,Depend on Figure 2 It can be known that 296cm -1 The absorption peak is in the hydrated phase Li. x La3Zr2O 12-y (OH) y Characteristic peaks, therefore, after hydrothermal reaction, garnet phase Li7La3Zr2O 12 It successfully transformed into the hydrogarnet phase.
[0047] S2, Li garnet phase x La3Zr2O 12-y (OH) y The powder (hydrogarnet phase LLZO powder) was dispersed in 200 mL of anhydrous ethanol, and 2 wt% of a fluorinated silane coupling agent (PFDTES) was added. The mixture was refluxed at 70 °C for 3 h, followed by centrifugation and washing three times, and vacuum drying at 70 °C for 6 h to obtain hydrophobically modified LLZO powder (see structural schematic diagram). Figure 1 ).
[0048] S3. Mix 20 parts by weight of hydrophobically modified LLZO powder, 0.3 parts by weight of sodium polyacrylate dispersant, 3 parts by weight of SBR / CMC binder, and 80 parts by weight of deionized water. Disperse at high speed for 30 minutes and then mill to a particle size D. 50 A solid electrolyte coating slurry with a thickness of approximately 1.2 μm was obtained. The LiOH content in the solid electrolyte coating slurry was <5 ppm, the pH was 8.1, and no sedimentation was observed after standing for 7 days, indicating good stability.
[0049] S4. The solid electrolyte coating slurry was coated onto a 9μm, 45% porosity PE base membrane (purchased from Shenzhen Xingyuan Material Technology Co., Ltd., SW509C+) using a micro-concave roller method. The wet film thickness of the solid electrolyte coating was controlled to be 10μm. After baking at 80℃ for 20min, an aqueous solid electrolyte coated membrane was obtained. The gas permeability increase of the obtained membrane was 12s / 100cc (GB / T36363-2018), indicating that the pores were not blocked. The dry film thickness of the solid electrolyte coating was 3μm. The scanning electron microscope image of the prepared aqueous solid electrolyte coated membrane is shown below. Figure 3 ,Depend on Figure 3 It is known that the diaphragm prepared in Example 1 has a uniform solid electrolyte coating without agglomeration and without cracking.
[0050] The prepared aqueous solid electrolyte coated membrane was used in NCM811||Li full cells, and the capacity retention rate reached 92% after 500 cycles at 1C.
[0051] Example 2
[0052] This embodiment provides a method for preparing an aqueous solid electrolyte coated membrane, comprising the following steps:
[0053] S1, commercial garnet phase Li7La3Zr2O 12 20g of the powder was added to 200mL of deionized water containing 0.2g of sodium polyacrylate dispersant, and placed in a 300mL autoclave. The mixture was then subjected to a hydrothermal reaction at 140℃ for 24 hours. During the reaction, some H₂O was generated. + / Li + Exchange to obtain garnet phase Li x La3Zr2O 12-y (OH) y The powder (x+y≈7, x / y≈0.6) is weakly acidic, stable in water, and no longer generates soluble LiOH.
[0054] S2, Li garnet phase x La3Zr2O 12-y (OH) y The powder (hydrogarnet phase LLZO powder) was dispersed in 200 mL of anhydrous ethanol, and 2 wt% of dodecyltriethoxysilane was added. The mixture was refluxed at 70 °C for 3 h, then centrifuged, washed three times, and vacuum dried at 70 °C for 6 h to obtain hydrophobically modified LLZO powder.
[0055] S3. Mix 10 parts by weight of hydrophobically modified LLZO powder, 0.1 parts by weight of sodium polyacrylate dispersant, 1 part by weight of SBR / CMC binder, and 70 parts by weight of deionized water. Disperse at high speed for 30 minutes and then mill to a particle size D. 50 A solid electrolyte coating slurry with a thickness of 1.0 μm was obtained. The LiOH content in the solid electrolyte coating slurry was <5 ppm, the pH was 8.1, and no sedimentation was observed after standing for 7 days, indicating good stability.
[0056] S4. The solid electrolyte coating slurry was coated onto a 2μm, 30% porosity PE base membrane (purchased from Shenzhen Xingyuan Material Technology Co., Ltd., SW509C+) using a micro-grooving roller. The wet film thickness of the solid electrolyte coating was controlled to be 5μm. After baking at 80℃ for 20min, an aqueous solid electrolyte coated diaphragm was obtained. The resulting diaphragm showed an air permeability increase of 10s / 100cc (GB / T36363-2018), indicating that the pores were not blocked. The dry film thickness of the solid electrolyte coating was 3μm.
[0057] The prepared aqueous solid electrolyte coated membrane was used in NCM811||Li full cells, and the capacity retention reached 90% after 500 cycles at 1C. Meanwhile, no failure phenomena such as binder hardening, particle shedding or structural fracture were observed on the coating surface during the cycling process.
[0058] Example 3
[0059] This embodiment provides a method for preparing an aqueous solid electrolyte coated membrane, comprising the following steps:
[0060] S1, commercial garnet phase Li7La3Zr2O 12 20g of the powder was added to 200mL of deionized water containing 0.2g of sodium polyacrylate dispersant, and placed in a 300mL autoclave. The mixture was then hydrothermally reacted at 180℃ for 4 hours. During the reaction, some H₂O was generated. + / Li + Exchange to obtain garnet phase Li x La3Zr2O 12-y (OH) y The powder (x+y≈7, x / y≈0.6) is weakly acidic, stable in water, and no longer generates soluble LiOH.
[0061] S2, Li garnet phase x La3Zr2O 12-y (OH) y The powder (hydraulic phase LLZO powder) was dispersed in 200 mL of anhydrous ethanol, and 2 wt% dodecyltriethoxysilane was added. The mixture was refluxed at 70 °C for 3 h, followed by centrifugation and washing three times, and then vacuum drying at 70 °C for 6 h to obtain hydrophobically modified LLZO powder. The surface contact angle of the hydrophobically modified LLZO powder was 135°, exhibiting significant hydrophobicity.
[0062] S3. Mix 30 parts of hydrophobically modified LLZO powder, 0.5 parts of sodium polyacrylate dispersant, 5 parts of CMC binder, and 100 parts of deionized water according to the following mass ratios: disperse at high speed for 30 minutes, and then mill to a particle size D. 50 A solid electrolyte coating slurry was obtained with a thickness of 5.0 μm. The LiOH content in the solid electrolyte coating slurry was <5 ppm, the pH was 8.1, and no sedimentation was observed after standing for 7 days, indicating good stability.
[0063] S4. The solid electrolyte coating slurry was coated onto a 50μm, 80% porosity PE base membrane (purchased from Shenzhen Xingyuan Material Technology Co., Ltd., SW509C+) using a micro-grooving roller. The wet film thickness of the solid electrolyte coating was controlled at 15μm. After baking at 80℃ for 20min, an aqueous solid electrolyte coated membrane was obtained. The resulting membrane showed an air permeability increase of 15s / 100cc (GB / T36363-2018), indicating that the pores were not blocked. The dry film thickness of the solid electrolyte coating was 3μm.
[0064] The prepared aqueous solid electrolyte coated membrane was used in NCM811||Li full cells, and the capacity retention rate reached 91% after 500 cycles at 1C. Meanwhile, no failure phenomena such as binder hardening, particle shedding or structural fracture were observed on the coating surface during the cycling process.
[0065] Comparative Example 1
[0066] The difference between this comparative example and Example 1 is that it does not include S1 and S2, and S3 uses the garnet phase Li7La3Zr2O. 12 Solid electrolyte coating slurry was prepared by replacing hydrophobically modified LLZO powder, and other aspects were the same as in Example 1.
[0067] Due to the commercial garnet phase Li7La3Zr2O 12 It reacts violently with water. + / Li + The exchange process generates a large amount of LiOH, making the solid electrolyte coating slurry highly alkaline (pH>13) within a short period of time, leading to the rapid failure of binders such as PVDF / SBR. Significant flocculation and sedimentation occur as early as one hour after the solid electrolyte coating slurry is prepared.
[0068] The prepared aqueous solid electrolyte coated membrane exhibited a permeability increase of 65 s / 100 cc, indicating significant pore blockage. With a contact angle of only 45° and strong wettability, water easily penetrated the powder structure. After 500 cycles at 1C, the full cell retained only 68% of its capacity.
[0069] Comparative Example 2
[0070] The difference between this comparative example and Example 1 is that it does not include the garnet phase Li in S2 and S3. x La3Zr2O 12-y (OH) y The hydrophobically modified LLZO powder was replaced with a powder, and the rest was the same as in Example 1.
[0071] Although the obtained garnet phase powder no longer generates LiOH on a large scale, its surface remains hydrophilic with a contact angle of only 75°. The slurry has a pH of approximately 9.8 in water, with a LiOH concentration of about 50 ppm. The resulting aqueous solid electrolyte coating membrane exhibits a permeability increase of 25 s / 100 cc and slight pore blockage. After 500 cycles, the capacity retention rate is 83%. The binder did not undergo severe hardening, but localized coating shrinkage and cracking were still observed.
[0072] Comparative Example 3
[0073] The difference between this comparative example and Example 1 is that it does not include the use of garnet phase Li7La3Zr2O in S1 and S2. 12 Powder substitute for hydragamate phase Li x La3Zr2O 12-y (OH) y Powder, for garnet phase Li7La3Zr2O 12 The powder underwent silane coupling modification, otherwise the same as in Example 1. Although the surface contact angle of the hydrophobically modified garnet phase LLZO powder reached 110°, the internal structure still contained active Li that could react with water. + The prepared solid electrolyte coating slurry had a LiOH concentration as high as 300 ppm, resulting in a system pH > 11 and significant sedimentation within 24 hours. The obtained aqueous solid electrolyte coating membrane showed a permeability increase of 40 s / 100 cc. After 500 battery cycles, the capacity retention was approximately 78%, and slight powder shedding of the coating occurred, indicating that the hydrophobic layer could not prevent internal LiOH from entering the membrane. + Dissolution.
[0074] II. Testing Methods
[0075] The solid electrolyte coating slurry, aqueous solid electrolyte coating membrane, and battery of the above embodiments and comparative examples were subjected to relevant physicochemical and performance tests. The test items and methods are as follows:
[0076] 1. Water Contact Angle of Coating: The test was conducted using a contact angle meter at room temperature (25±2℃) and relative humidity of 40-60%. The solid electrolyte coating membrane to be tested was cut into 2cm×2cm samples and laid flat on the sample stage. A droplet of deionized water was added to the coating surface using a microsyringe, with the droplet volume controlled at 3-5μL. The water contact angle was recorded after the droplet stabilized (approximately 3 seconds). At least five different locations were selected for testing for each sample, and the average value was taken as the water contact angle of that sample.
[0077] 2. LiOH generation: A 10 cm² sample of the coated membrane was cut and placed in a sealed container. A measured amount of deionized water (50 mL) was added, and the mixture was allowed to stand at 25 °C for 24 h. The solid and liquid phases were then separated by filtration or centrifugation, and the supernatant was collected. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to analyze the LiOH formation in the solution. + The content was quantitatively analyzed and converted into the amount of LiOH generated (ppm). Each sample was tested in triplicate, and the range of the three test results was taken.
[0078] 3. Air permeability increment: Following GB / T36363-2018, an air permeability tester was used. The time required for air to pass through a unit volume (100cc) of the membrane before and after coating with the aqueous solid electrolyte coating was measured. The time difference between the two measurements was defined as the air permeability increment. Each sample was tested at least five times, and the average value was taken as the final result.
[0079] 4. Slurry stability: The prepared coating slurry was placed in a sealed glass bottle and allowed to stand at 25°C. The stratification and sedimentation of the slurry were observed at 0h, 24h, 72h and 7d, and the sedimentation height or whether obvious hard sedimentation occurred was recorded.
[0080] 5. Ionic Conductivity: The coated separator was cut into circular pieces (16-18 mm in diameter) and sandwiched between stainless steel barrier electrodes to assemble a symmetrical cell (SS / separator / SS). AC impedance was measured at 25°C using an electrochemical workstation, with a test frequency range of 1 MHz to 0.1 Hz and a perturbation voltage of 5-10 mV. Bulk resistance was obtained by Nyquist curve fitting, and ionic conductivity was calculated based on the separator thickness and effective area.
[0081] 6. Capacity Retention: NCM811||Li full cells were assembled using the prepared aqueous solid electrolyte coated separator. Charge-discharge cycle tests were conducted at a set rate (1C) at 25°C. The capacity retention rate after a specified number of cycles (500 cycles) was calculated based on the initial discharge capacity. Capacity decay trend and cycle stability were recorded during the test.
[0082] 7. Adhesive failure phenomena: Use scanning electron microscopy (SEM) to observe whether the coating shows cracking, chalking, or peeling from the base film. If the coating shows obvious peeling, chalking, or cross-linking hardening of the adhesive leading to structural damage, it is determined that adhesive failure has occurred.
[0083] III. Test Results
[0084] The performance test results of the solid electrolyte coating slurry, aqueous solid electrolyte coating membrane and battery of the above embodiments and comparative examples are shown in Table 1.
[0085] Table 1 Performance Test Results
[0086]
[0087] Note: The ionic conductivity of the comparative example is the powder value. In actual use, the ionic conductivity of the membrane decreases significantly due to LiOH clogging the pores.
[0088] Table 1 shows that the aqueous solid electrolyte coating membranes prepared in Examples 1-3 of this invention have a LiOH generation amount of <5ppm, achieving a permeability increase of <20s / 100cc, effectively avoiding membrane pore blockage, and the battery cycle performance is significantly better than that of Comparative Examples 1-3. In contrast, the aqueous solid electrolyte coating membranes prepared in Comparative Examples 1-3 all have a large LiOH generation amount. Therefore, in the preparation method of the aqueous solid electrolyte coating membrane of this application, the preparation of hydrogarnet phase Li... x La3Zr2O 12-y (OH) y Powder, para-hydraulic phase Li x La3Zr2O 12-y (OH) y Hydrophobic modification of powder has a synergistic effect in reducing LiOH generation, thereby increasing the gas permeability of the prepared solid electrolyte coating membrane by <20s / 100cc and giving the prepared battery excellent cycle performance.
[0089] Examples 1-3, due to the use of an aqueous preparation process, achieve no organic solvent pollution, meet environmental protection requirements, and do not have the problem of adhesive failure.
[0090] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
[0092] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A method for preparing an aqueous solid electrolyte coated membrane, characterized in that, Includes the following steps: Hydrogarnet-phase lithium lanthanum zirconium oxide is prepared by hydrothermal reaction. The hydrogarnet-phase lithium lanthanum zirconium oxide is then hydrophobically modified to obtain hydrophobic hydrogarnet-phase lithium lanthanum zirconium oxide. The hydrophobic hydrogarnet-phase lithium lanthanum zirconium oxide, dispersant, binder, and water are mixed evenly to obtain a solid electrolyte coating slurry. The solid electrolyte coating slurry is coated onto a base film and dried to obtain an aqueous solid electrolyte coating membrane.
2. The method for preparing the aqueous solid electrolyte coating membrane as described in claim 1, characterized in that, The garnet-phase lithium lanthanum zirconium oxide is a garnet-phase Li x La3Zr2O 12-y (OH) y Where x + y = 7, 0.2 <x / y<1; The hydrophobic garnet phase lithium lanthanum zirconium oxide has an ionic conductivity of 10. -6 ~10 -4 S / cm, particle size 50nm~10μm, surface contact angle >100°.
3. The method for preparing the aqueous solid electrolyte coating membrane as described in claim 1, characterized in that, The hydrothermal reaction is to prepare garnet-phase lithium lanthanum zirconium oxide by hydrothermal reaction of garnet phase lithium lanthanum zirconium oxide at 140-180℃ for 4-24 hours.
4. The method for preparing the aqueous solid electrolyte coated membrane as described in claim 1, characterized in that, The hydrophobic modification of the garnet phase lithium lanthanum zirconium oxide was performed using a silane coupling agent.
5. The method for preparing the aqueous solid electrolyte coated membrane as described in claim 4, characterized in that, The silane coupling agent is a silane coupling agent containing long-chain alkyl or fluoroalkyl groups; The amount of the silane coupling agent is 1 to 5 wt% of the mass of the garnet phase lithium lanthanum zirconium oxide.
6. The method for preparing the aqueous solid electrolyte coated membrane as described in claim 1, characterized in that, The long-chain alkyl-containing silane coupling agent is dodecyltriethoxysilane, and the fluorinated alkyl-containing silane coupling agent is tridecylfluorooctyltriethoxysilane. The dispersant is selected from one or more of sodium polyacrylate, sodium alkyl sulfonate, or alkyl carboxylates.
7. The method for preparing the aqueous solid electrolyte coated membrane as described in claim 1, characterized in that, The adhesive is selected from one or more of polyvinylidene fluoride, styrene-butadiene rubber latex, or waterborne polyurethane.
8. The method for preparing the aqueous solid electrolyte coating membrane as described in claim 1, characterized in that, At least one of the following conditions must be met: The base membrane is selected from polyethylene microporous membrane, polypropylene microporous membrane, polyethylene / polypropylene composite membrane or non-woven fabric membrane, and the thickness of the base membrane is 2-50 μm, and the porosity is 30-80%. The solid electrolyte coating slurry is prepared by uniformly mixing 10-30 parts of hydrophobic garnet-phase lithium lanthanum zirconium oxide, 0.1-0.5 parts of dispersant, 1-5 parts of binder, and 70-100 parts of water to obtain the solid electrolyte coating slurry. The solid electrolyte coating slurry is coated onto the base film by dip coating, microgravure coating or a combination thereof, and the wet film thickness of the solid electrolyte coating slurry is 5-15 μm. In the solid electrolyte coating slurry, the particle size D of the hydrophobic garnet phase lithium lanthanum zirconium oxide is... 50 The size is 1–5 μm.
9. A water-based solid electrolyte coating membrane prepared by the preparation method according to any one of claims 1-8, characterized in that, include Base membrane, A solid electrolyte coating is located on at least one surface of the base film.
10. The aqueous solid electrolyte coating membrane as described in claim 9, characterized in that, The thickness of the solid electrolyte coating is 1–10 μm.