Battery diaphragm, preparation method thereof and battery
By loading organosilicon and organoboron compounds onto the surface of the alumina-coated base film to form a hybrid network that captures HF and H2O, the performance degradation problem caused by moisture in lithium-ion batteries is solved, and the electrochemical performance of the battery is improved.
Patent Information
- Application Number
- CN202511121658.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-12
- Publication Date
- 2025-11-07
AI Technical Summary
In existing lithium-ion batteries, the high-nickel ternary cathode material is sensitive to moisture, which leads to the generation of HF, which in turn corrodes the cathode material and SEI film, resulting in capacity decay, shortened cycle life and reduced ionic conductivity. The water absorption of ceramic coatings cannot effectively solve this problem.
Organosilicon and organoboron compounds are loaded onto the surface of the alumina coating base film and bonded in a hydrogen chloride atmosphere to form Si-OB, Si-O-Al and Al-O-Al hybrid networks, which capture HF and H2O and generate new bonds such as Al-F, Si-OH, F-Si-O, FBOH, etc., thus avoiding capacity decay and shortened lifetime.
It effectively adsorbs HF and H2O, preventing lithium battery capacity decay and lifespan shortening, improving ionic conductivity, and enhancing battery performance.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of battery materials, in particular to a battery separator and a preparation method thereof and a battery. BACKGROUND
[0002] As one of the key components of lithium ion batteries, the separator plays an important role in preventing the contact between the positive and negative electrodes while allowing the transmission of lithium ions. With the diversification of electrode materials towards high energy density and long life, controlling moisture in the battery system is an important problem that limits the life of the battery. At present, due to the capacity advantage, high-nickel ternary positive electrode materials have gradually become the first choice for power batteries. However, as the nickel content increases, they are extremely sensitive to water. The most commonly used non-aqueous liquid electrolyte in lithium ion batteries includes lithium hexafluorophosphate (LiPF6) salt and carbonate solvent components. However, the decomposition of LiPF6 salt is almost inevitable (LiPF6→LiF+PF5). In the presence of trace amounts of moisture, LiPF6 and PF5 generate hydrofluoric acid (HF) through the following reactions: LiPF6+H2O→2HF+POF3+LiF; PF5+H2O→HF+POF3; HF as a decomposition product will cause problems such as capacity attenuation, cycle life shortening, ion conductivity reduction, etc. in lithium ion batteries by dissolving transition metal ions (such as Fe, Co, Mn and Ni) in the positive electrode and decomposing the SEI film.
[0003] At present, by coating ceramics such as aluminum oxide on the surface of polyolefin separators, it can improve the thermal stability and safety of the separator, improve the mechanical strength, optimize the electrolyte wettability, enhance the electrochemical performance, and prolong the cycle life, etc. Its technology iteration and market share speed is accelerating, and it has gradually become one of the mainstream choices for lithium battery separator modification. However, it cannot effectively improve the problem of battery performance decline caused by moisture, and the water absorption of the ceramic coating will inevitably introduce new moisture, which will exacerbate the decline in battery performance.
[0004] In view of this, the present application is proposed. SUMMARY
[0005] The purpose of the present application is to provide a battery separator and a preparation method thereof and a battery, aiming to improve at least one problem mentioned in the background art.
[0006] The present application is implemented as follows: In a first aspect, the present application provides a preparation method of a battery separator, comprising: A dispersion liquid is provided, in which a silicone compound and an organic boron compound are dissolved, and the content of the silicone compound and the organic boron compound in the dispersion liquid is 20-45%wt, 5-15%wt; a base film is provided, and the surface of the base film has an alumina coating layer; The base film is immersed into the dispersion liquid, so that the dispersion liquid is loaded on the surface of the base film, and then the solvent in the dispersion liquid on the surface of the base film is volatilized at 10-30℃ to obtain a first intermediate product separator film; The first intermediate product separator film is placed in a hydrochloric acid atmosphere for 12-48h to obtain a second intermediate product separator film; The second intermediate product separator film is cleaned and then dried to obtain a battery separator film.
[0007] In an optional embodiment, the silicone compound is selected from at least one of tetraethoxysilane, tetramethoxysilane and aminopropyl triethoxysilane. In an optional embodiment, the organic boron compound is selected from at least one of trimethyl borate and triethyl borate.
[0008] In an optional embodiment, the time for which the base film is immersed in the dispersion liquid is 0.5-1.5h.
[0009] In an optional embodiment, the solvent in the dispersion liquid is selected from at least one of ethyl acetate, dichloromethane and methanol.
[0010] In an optional embodiment, the temperature for volatilizing the solvent in the dispersion liquid on the surface of the base film is 10-30℃.
[0011] In an optional embodiment, the drying temperature is 30-80℃, and the time is 6-24h.
[0012] In an optional embodiment, the base film is a polyethylene film, and the surface of the polyethylene film has an alumina coating layer.
[0013] In a second aspect, the present application provides a battery separator film, which is prepared by using the preparation method according to any one of the preceding embodiments.
[0014] In a third aspect, the present application provides a battery, which comprises the battery separator film according to the preceding embodiments, and the electrolyte of the battery comprises a hexafluorophosphate salt.
[0015] The present application has the following beneficial effects: The preparation method provided by the embodiment of the present application can form a Si-O-B, Si-O-Al and Al-O-Al hybrid network on the surface of the base film by loading an organic silicon compound and an organic boron compound on the surface of the base film with an alumina coating, and then performing a bonding reaction in a hydrogen chloride atmosphere, so as to attract and capture HF and H2O introduced by the liquid electrolyte or generated in the cycle process. The captured HF and H2O can break the bonding of Si-O-B, Si-O-Al and Al-O-Al, and generate new bonds such as Al-F, Si-O-H, F-Si-O, F-B-O-H, etc., thereby avoiding problems such as capacity attenuation, cycle life shortening, ion conductivity reduction and the like of the lithium battery caused by too high content of HF and H2O. DETAILED DESCRIPTION
[0016] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased in the market.
[0017] The features and performances of the present application will be further described in detail below in combination with the embodiments.
[0018] The embodiment of the present application provides a preparation method of a battery separator, comprising: A dispersion liquid is provided, and an organic silicon compound and an organic boron compound are dissolved in the dispersion liquid, and the content of the organic silicon compound and the organic boron compound in the dispersion liquid is 20-45%wt and 5-15%wt; A base film is provided, and the surface of the base film has an alumina coating; The base film is immersed in the dispersion liquid for 0.5-1.5h, so as to load the dispersion liquid on the surface of the base film, and then the solvent in the dispersion liquid on the surface of the base film is volatilized at 10-30℃ to obtain a first intermediate product separator; the first intermediate product separator is placed in a hydrochloric acid atmosphere for 12-48h to obtain a second intermediate product separator; The second intermediate product separator is cleaned, and then dried to obtain a battery separator.
[0019] The preparation method provided by the embodiment of the present application can form a Si-O-B, Si-O-Al and Al-O-Al hybrid network on the surface of the base film by loading an organic silicon compound and an organic boron compound on the surface of the base film with an alumina coating, and then performing a bonding reaction in a hydrogen chloride atmosphere, so that HF and H2O introduced by the liquid electrolyte or generated in the cycle process can be attracted and captured. The captured HF and H2O can break the bonds of Si-O-B, Si-O-Al and Al-O-Al, and generate new bonds such as Al-F, Si-O-H, F-Si-O, F-B-O-H and the like, thereby avoiding problems such as capacity attenuation, cycle life shortening, ion conductivity reduction and the like of the lithium battery caused by excessive content of HF and H2O.
[0020] It should be noted that the reaction time in the hydrochloric acid atmosphere needs to be within the range required by the present application, and the reaction time required by the present application avoids both too short reaction time and incomplete reaction, and also avoids too long reaction time leading to re-decomposition of the hybrid network structure formed on the surface.
[0021] It should be noted that the organic silicon compound and the organic boron compound in the dispersion liquid need to be within the range required by the present application, and the range is appropriate, that is, it ensures that the organic silicon compound and the organic boron compound are within a suitable ratio range, and also avoids insufficient loading caused by too low concentration, and avoids plugging of the membrane pores caused by too high concentration.
[0022] It should be noted that the temperature for volatilizing the solvent needs to be within the range required by the present application, that is, it avoids residual solvent at too low temperature, and also prevents solvent gas from overflowing too fast to damage the uniformity of the surface coating layer at too high temperature.
[0023] Specifically, the preparation method is: S1, preparing a dispersion liquid The organic silicon compound and the organic boron compound are dissolved in a solvent to prepare a dispersion liquid.
[0024] Optionally, to make the prepared membrane have better electrochemical performance when applied in a battery, the siloxane is selected from at least one of tetraethoxysilane, tetramethoxysilane and aminopropyl triethoxysilane.
[0025] Optionally, to make the prepared membrane have better electrochemical performance when applied in a battery, the borate is selected from at least one of trimethyl borate and triethyl borate. Optionally, the solvent in the dispersion liquid is selected from at least one of ethyl acetate, dichloromethane and methanol.
[0026] Optionally, to make the surface of the final prepared separator membrane have a better hybrid network structure and have a better adsorption effect on HF and H2O, the content of the organosilicon compound and the organoboron compound in the dispersion liquid is 20-45%wt (for example, 20%wt, 30%wt, 35%wt, 40%wt or 45%wt), 5-15%wt (for example, 5%wt, 10%wt or 15%wt).
[0027] Optionally, the time for which the base film is immersed in the dispersion liquid is 0.5-1.5h (for example, 0.5h, 1h or 1.5h).
[0028] It should be noted that the above immersion time can prevent the effective component from being adsorbed in a small amount due to a too short immersion time, and can also prevent the effective component from being too much to block the membrane pores due to a too long immersion time.
[0029] Optionally, the base film is a polyethylene film with an alumina coating on the surface.
[0030] S2, solvent evaporation After the base film is taken out of the dispersion liquid, the base film is placed at a temperature of 10-30℃ (for example, 10℃, 20℃ or 30℃) to evaporate the solvent to obtain a first intermediate product separator membrane.
[0031] At this temperature, both the solvent residue due to a too low temperature and the solvent gas overflow due to a too high temperature can be prevented, so that the effective component is uniformly coated.
[0032] S3, bonding reaction The first intermediate product separator membrane is placed in a hydrochloric acid atmosphere to perform a bonding reaction. In this atmosphere, the organosilicon compound and the organoboron compound react with the alumina on the surface of the separator membrane to form a Si-O-B, Si-O-Al and Al-O-Al hybrid network, and a second intermediate product separator membrane is obtained.
[0033] Optionally, the reaction time is 12-48h (for example, 12h, 15h, 20h, 25h, 30h, 35h, 40h or 48h).
[0034] S4, cleaning and drying The second intermediate product separator membrane is cleaned with distilled water and ethanol in sequence, and finally vacuum dried at a temperature of 30-80℃ (for example, 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃) for 6-24h (for example, 6h, 10h, 15h, 20h or 24h) to obtain a finished battery separator membrane.
[0035] The drying temperature and the drying time in the above vacuum drying are moderate, which can avoid both the water residue due to a too low temperature and a too short time and the energy consumption.
[0036] The battery separator provided by the embodiment of the application is prepared by the preparation method provided by the embodiment of the application.
[0037] The battery provided by the embodiment of the application comprises the battery separator provided by the embodiment of the application, and the electrolyte of the battery comprises hexafluorophosphate.
[0038] The battery can be a lithium ion battery or a sodium ion battery. When the battery is a lithium ion battery, the hexafluorophosphate in the electrolyte is lithium hexafluorophosphate; when the battery is a sodium ion battery, the hexafluorophosphate in the electrolyte is sodium hexafluorophosphate.
[0039] Embodiment 1 Ethyl acetate is used to dissolve tetraethoxysilane and trimethyl borate, and a dispersion liquid is obtained, wherein the concentrations of the tetraethoxysilane and the trimethyl borate are 30%wt and 10%wt respectively; The polyethylene base film with an alumina coating on the surface is immersed in the dispersion liquid for 1h, and then the base film is taken out to volatilize the ethyl acetate on the surface of the base film at 20℃ to obtain a first intermediate product separator; The first intermediate product separator is placed in a hydrochloric acid atmosphere to react for 30h to obtain a second intermediate product separator; The second intermediate product separator is sequentially cleaned with distilled water and ethanol, and then dried at 50℃ for 15h to obtain a finished product separator.
[0040] Embodiment 2 Methylene chloride is used to dissolve tetramethoxysilane and triethyl borate, and a dispersion liquid is obtained, wherein the concentrations of the tetramethoxysilane and the triethyl borate are 20%wt and 15%wt respectively; The polyethylene base film with an alumina coating on the surface is immersed in the dispersion liquid for 0.5h, and then the base film is taken out to volatilize the methylene chloride on the surface of the base film at 10℃ to obtain a first intermediate product separator; The first intermediate product separator is placed in a hydrochloric acid atmosphere to react for 12h to obtain a second intermediate product separator; The second intermediate product separator is sequentially cleaned with distilled water and ethanol, and then dried at 30℃ for 24h to obtain a finished product separator.
[0041] Embodiment 3 Methanol is used to dissolve aminopropyl triethoxysilane and trimethyl borate, and a dispersion liquid is obtained, wherein the concentrations of the aminopropyl triethoxysilane and the trimethyl borate are 45%wt and 5%wt respectively; The polyethylene base film with an alumina coating on the surface is immersed in the dispersion liquid for 1.5h, and then the base film is taken out to volatilize the methanol on the surface of the base film at 30℃ to obtain a first intermediate product separator; The first intermediate product separator is placed in a hydrochloric acid atmosphere to react for 48h to obtain a second intermediate product separator; The second intermediate product separator film is cleaned with distilled water and ethanol in sequence, and then dried at 80℃ for 6h to obtain the finished separator film.
[0042] Comparative Example 1 This comparative example is basically the same as Example 1, except that an equivalent amount of trimethyl borate is used to replace tetraethoxysilane.
[0043] Comparative Example 2 This comparative example is basically the same as Example 1, except that an equivalent amount of tetraethoxysilane is used to replace trimethyl borate.
[0044] Comparative Example 3 This comparative example is basically the same as Example 1, except that the concentrations of tetraethoxysilane and trimethyl borate in this comparative example are too high, which are 51%wt and 17%wt, respectively.
[0045] Comparative Example 4 This comparative example is basically the same as Example 3, except that the reaction time in the hydrochloric acid atmosphere is too long, which is 55h.
[0046] Comparative Example 5 This comparative example is basically the same as Example 3, except that the temperature for solvent evaporation is too high, which is 40℃.
[0047] Comparative Example 6 Polyethylene film with an aluminum oxide coating without any treatment.
[0048] Experimental Example The separator films prepared in each example and comparative example are assembled into batteries, and the electrochemical performance of the batteries prepared in each example and comparative example is measured.
[0049] The battery assembly method is as follows: the battery model is LIR2025, the positive electrode sheet is an active layer coated on an aluminum foil, the active layer includes lithium cobalt oxide, acetylene black and PVDF in a mass ratio of 8:1:1; the negative electrode sheet is a lithium sheet; and the electrolyte is lithium hexafluorophosphate.
[0050] The electrochemical performance test method and test conditions are as follows: the ionic conductivity is tested by an alternating current impedance spectrum method, the frequency range is 0.1Hz~1MHz, the voltage amplitude is 5mV, and the test temperature is 25℃; the battery capacity retention rate is tested by a constant current charge and discharge method, specifically, 0.5C constant current charging is performed until the voltage is 3.75V, then constant voltage charging is continued until the current is 0.05C, finally, 0.2C discharging is performed until the voltage is 2.5V, the test temperature is 25℃, and the proportion of the capacity after 100 times of charge and discharge to the initial capacity is calculated, which is the capacity retention rate; the cycle performance test is performed by a constant current charge and discharge method, the charge and discharge currents are both 0.5C, and the capacity decay threshold is 80% of the initial capacity.
[0051] The test results are recorded in Table 1.
[0052] 1Electrochemical performance test results of various embodiments and comparative examples
[0053] As can be seen from Table 1, the separators prepared by various embodiments of the application have higher ion conductivity, capacity retention rate and cycle number when assembled into batteries compared with Comparative Example 6, indicating that modification of the coating surface with aluminum oxide with an organic silicon compound and an organic boron compound can improve the electrochemical performance of the separator.
[0054] Comparing Comparative Examples 1 and 2 with Example 1, the electrochemical performance of the batteries assembled from Comparative Examples 1 and 2 is significantly poorer than that of Example 1, indicating that the organic silicon compound and the organic boron compound have a significant synergistic effect in enhancing the electrochemical performance of the separator, and their joint modification of the separator with an aluminum oxide coating can achieve better results; Comparing Comparative Example 3 with Example 1, the electrochemical performance of Comparative Example 3 is poorer, indicating that too high a concentration of the dispersion liquid can cause too much loading on the surface of the separator, which can cause the pores of the separator to be blocked, resulting in a decrease in electrochemical performance; Comparing Comparative Example 4 with Example 3, the electrochemical performance of Comparative Example 4 is poorer, indicating that too long a reaction time in a hydrochloric acid environment can cause the hybrid network structure to be re-decomposed, thereby causing a decrease in electrochemical performance; Comparing Comparative Example 5 with Example 3, the electrochemical performance of Comparative Example 5 is poorer, indicating that too high a volatilization temperature of ethyl acetate can cause ethyl acetate to volatilize too quickly, which can destroy the uniform coating of the active ingredients, thereby causing a decrease in electrochemical performance.
[0055] In summary, the preparation method provided by the embodiments of the application can load an organic silicon compound and an organic boron compound on the surface of a base film with an aluminum oxide coating, and then perform a bonding reaction in a hydrogen chloride atmosphere, which can form a Si-O-B, Si-O-Al and Al-O-Al hybrid network on the surface of the base film, which can attract and capture HF and H2O introduced by the liquid electrolyte or generated during the cycle process. The captured HF and H2O can break the bonds of Si-O-B, Si-O-Al and Al-O-Al to generate new bonds, such as Al-F, Si-O-H, F-Si-O, F-B-O-H, etc., thereby avoiding problems such as capacity decay, cycle life shortening and ion conductivity reduction of lithium batteries caused by too high a content of HF and H2O. Therefore, the separator prepared by the preparation method has good electrochemical performance when assembled into a battery.
[0056] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.
Claims
1. A method of preparing a battery separator, characterized by, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
2. The production method according to claim 1, characterized by, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
3. The preparation method according to claim 1, characterized in that, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
4. The method of claim 1, wherein, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
5. The preparation method according to claim 1, characterized in that, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
6. The method of claim 1, wherein, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
7. The preparation method according to claim 1, characterized in that, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
8. The method of claim 1, wherein, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
9. A battery separator characterized by, The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators.
10. A battery, characterized by The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation method of a battery separator, and belongs to the technical field of battery separators. The application provides a preparation