Manganese-doped boehmite lithium ion battery diaphragm and preparation method thereof

Abstract

The invention discloses a manganese-doped boehmite lithium ion battery diaphragm and a preparation method thereof, and belongs to the technical field of lithium ions. Metal manganese ions are doped in boehmite through a hydrothermal method, the conductivity of the manganese-doped boehmite lithium ion battery diaphragm is improved, meanwhile, the contact angle between the prepared manganese-doped boehmite lithium ion battery diaphragm and an electrolyte is small, the electrolyte can more rapidly and fully infiltrate the whole diaphragm pore channel, and the battery performance is improved. The electrochemical performance of the lithium ion battery is favorably improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery materials technology, specifically to a manganese-doped boehmite lithium-ion battery separator and its preparation method. Background Technology

[0002] Boehmite, a novel layered aluminate mineral, possesses a two-dimensional layered structure similar to hydrotalcite. It is synthesized via a controlled hydrolysis / precipitation method, and its typical structure is γ-AlOOH crystal form, with negatively charged AlO2 atoms forming the interlayers. - Layers with exchangeable cations (such as Na) + Ca 2+ It is composed of (etc.), and its general chemical formula can be represented as Al2O3·nH2O (n≥1), and it also has a high specific surface area (up to 200-500m²). 2 Boehmite possesses characteristics such as tunable pore structure and abundant surface active sites. Its unique layered structure endows it with ion exchange capacity and adsorption properties, demonstrating significant advantages in catalytic supports, environmental remediation, and battery separators. In recent years, the application of boehmite in lithium-ion batteries has gradually gained attention, particularly in high-capacity cathode materials and separator coatings, where it exhibits unique advantages. Its high specific surface area and tunable interlayer structure can be further optimized for electrochemical performance by introducing functional components (such as metal cations). However, pure boehmite materials still have shortcomings in lithium-ion transport rate, cycle stability, and conductivity. Summary of the Invention

[0003] The main objective of this invention is to propose a manganese-doped boehmite lithium-ion battery separator and its preparation method. This invention improves the conductivity of the manganese-doped boehmite lithium-ion battery separator by doping manganese ions into boehmite using a hydrothermal method. At the same time, the manganese-doped boehmite lithium-ion battery separator prepared by this invention has a small contact angle with the electrolyte, allowing the electrolyte to more quickly and fully wet the entire separator pores, which is beneficial to improving the electrochemical performance of the lithium-ion battery.

[0004] The technical solution of the present invention is achieved as follows:

[0005] In a first aspect, the present invention provides a manganese-doped boehmite lithium-ion battery separator, comprising a base film and a manganese-doped boehmite coating located on the surface of the base film; wherein the manganese-doped boehmite coating comprises the following raw materials: manganese-doped boehmite, organic polymer binder, dispersant, and organic solvent.

[0006] Preferably, the base film is a PE film.

[0007] Secondly, the present invention also proposes a method for preparing the manganese-doped boehmite lithium-ion battery separator, comprising the following steps:

[0008] S1. Add manganese-doped boehmite, organic polymer binder, and dispersant to an organic solvent in sequence, and mix and stir evenly to obtain manganese-doped boehmite slurry;

[0009] S2. Coat the base film with manganese-doped boehmite slurry and dry it to obtain a manganese-doped boehmite lithium-ion battery separator.

[0010] A further preferred embodiment of the preparation method of manganese-doped boehmite in step S1 is as follows:

[0011] S3. Mix aluminum salt, manganese salt, water and alkaline precipitant evenly, adjust the pH value to 10-11 to obtain a mixed solution;

[0012] S4. The mixture is transferred to a high-pressure reactor for hydrothermal reaction. After the reaction is completed, the mixture is centrifuged, the solid is collected, washed, dried, and ground to obtain manganese-doped boehmite.

[0013] Preferably, the aluminum salt in step S3 is aluminum nitrate nonahydrate.

[0014] Preferably, the manganese salt in step S3 is one of manganese chloride and manganese nitrate.

[0015] Preferably, the alkaline precipitant in step S3 is urea.

[0016] More preferably, the molar ratio of aluminum salt, manganese salt, water, and alkaline precipitant in step S3 is 1:0.02-0.1:1.25-1.3.

[0017] Preferably, the hydrothermal reaction temperature in step S4 is 120-200℃, and the reaction time is 20-30h.

[0018] Preferably, in step S1, the mass ratio of manganese-doped boehmite to organic polymer binder is 2-3:7-8; the organic polymer binder is polyvinylidene fluoride.

[0019] Preferably, the dispersant in step S1 is PEG fatty acid polyethylene glycol ester; the dispersant accounts for 1-3 wt% of the manganese-doped boehmite slurry.

[0020] Preferably, the organic solvent in step S1 is N-methylpyrrolidone.

[0021] Thirdly, the present invention also proposes a lithium-ion battery comprising the above-mentioned manganese-doped boehmite lithium-ion battery separator.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1) This invention uses a low-temperature hydrothermal method to achieve manganese ion doping, which is simple, energy-efficient, and environmentally friendly.

[0024] 2) This invention found that as the manganese content in boehmite increases and the thickness of the manganese-doped boehmite coating increases, the ionic conductivity of the resulting manganese-doped boehmite lithium-ion battery separator is significantly improved, and its cycle stability is better than that of the boehmite separator.

[0025] 3) This invention found that as the manganese content in boehmite increases, the hydroxyl density on the material surface increases, and the contact angle between the manganese-doped boehmite lithium-ion battery separator and the electrolyte decreases, allowing the electrolyte to wet the entire separator pores more quickly and fully, thus laying a solid foundation for improving the rate performance and cycle stability of the battery. Attached Figure Description

[0026] 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 related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram illustrating the preparation of the manganese-doped boehmite lithium-ion battery separator of the present invention;

[0028] Figure 2 The XRD patterns of Mn-BH with different manganese doping ratios obtained in Comparative Example 1 and Examples 1-3 of this invention are shown below.

[0029] Figure 3 The images shown are the SEM spectra of BH obtained in Comparative Example 1 and the SEM spectra of Mn-BH with different manganese doping ratios obtained in Examples 1-3 of this invention; wherein, Figure 3 b is the SEM image of BH obtained from Comparative Example 1. Figure 3 c-3e are SEM images of Mn-BH with different manganese doping ratios obtained in Examples 1, 2 and 3, respectively;

[0030] Figure 4 The contact angle test results between the BH obtained in Comparative Example 1 and the manganese-doped boehmite lithium-ion battery separators obtained in Examples 1-3 of this invention and the lithium battery electrolyte at room temperature are shown.

[0031] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0032] To avoid unnecessary details, unless otherwise specified, all items used in the following examples are commercially available products, and all methods used are conventional methods unless otherwise specified.

[0033] Chemical formula abbreviations in this invention:

[0034] BH: Boehmite;

[0035] Mn-BH: Manganese-doped boehmite;

[0036] Mn-BH / PE: Manganese-doped boehmite lithium-ion battery separator;

[0037] PEG: Polyethylene glycol fatty acid ester;

[0038] NMP: N-methylpyrrolidone;

[0039] PVDF: Polyvinylidene fluoride.

[0040] The PE microporous membrane was purchased from Enjie New Materials Co., Ltd., with a thickness of 16μm, a porosity of 40%, and a pore size of 400nm.

[0041] Unless otherwise specified, the manganese doping ratio described in this invention is based on the Mn / Al molar ratio.

[0042] Example 1

[0043] A method for preparing a manganese-doped boehmite lithium-ion battery separator, the schematic diagram of which is shown below. Figure 1 As shown, it includes the following steps:

[0044] S1. At room temperature, mix 4 mmol aluminum nitrate nonahydrate, 0.08 mmol manganese chloride tetrahydrate, 60 mL water and 5 mmol urea until homogeneous, and adjust the pH to 10 to obtain a mixture.

[0045] S2. The mixture is transferred to a 100mL high-pressure reactor and subjected to hydrothermal reaction at 160℃ for 24 hours. After the reaction is completed, it is centrifuged at 4000r / min. The solid is collected, washed, and dried at 60℃ for 12 hours. Finally, it is placed in a grinding dish and ground for 10 minutes to obtain manganese-doped boehmite powder, denoted as 2%Mn-BH, where 2% is the manganese doping ratio.

[0046] S3. Add 0.5g of manganese-doped boehmite powder, 2g of polyvinylidene fluoride, and 3.75g of N-methylpyrrolidone to 0.025g of oleic acid polyethylene glycol ester in sequence, and stir at room temperature for 30 minutes to obtain manganese-doped boehmite slurry.

[0047] S4. After ultrasonically cleaning the PE microporous membrane, place it in a forced-air oven at 40°C and dry for 30 minutes. Use a 3μm wire rod coater to evenly coat both sides of the PE microporous membrane with manganese-doped boehmite slurry. Let it stand for 10 minutes, then place it in a forced-air oven at 60°C and dry for 2 hours to obtain a manganese-doped boehmite lithium-ion battery separator, denoted as Mn-BH / PE.

[0048] Example 2

[0049] A method for preparing a manganese-doped boehmite lithium-ion battery separator includes the following steps:

[0050] S1. At room temperature, mix 4 mmol aluminum nitrate nonahydrate, 0.2 mmol manganese chloride tetrahydrate, 60 mL water and 5 mmol urea and stir until homogeneous. Adjust the pH to 11 to obtain a mixture.

[0051] S2. The mixture is transferred to a 100mL high-pressure reactor and subjected to hydrothermal reaction at 160℃ for 24 hours. After the reaction is completed, it is centrifuged at 4000r / min. The solid is collected, washed, and dried at 60℃ for 12 hours. Finally, it is placed in a grinding dish and ground for 10 minutes to obtain manganese-doped boehmite powder, denoted as 5%Mn-BH, where 5% is the manganese doping ratio.

[0052] S3. Add 0.5g of manganese-doped boehmite powder, 2g of polyvinylidene fluoride, and 3.75g of N-methylpyrrolidone to 0.025g of oleic acid polyethylene glycol ester in sequence, and stir at room temperature for 30 minutes to obtain manganese-doped boehmite slurry.

[0053] S4. After ultrasonically cleaning the PE microporous membrane, place it in a forced-air oven at 40°C and dry for 30 minutes. Use a 3μm wire rod coater to evenly coat both sides of the PE microporous membrane with manganese-doped boehmite slurry. Let it stand for 10 minutes, then place it in a forced-air oven at 60°C and dry for 2 hours to obtain a manganese-doped boehmite lithium-ion battery separator, denoted as Mn-BH / PE.

[0054] Example 3

[0055] A method for preparing a manganese-doped boehmite lithium-ion battery separator includes the following steps:

[0056] S1. At room temperature, mix 4 mmol aluminum nitrate nonahydrate, 0.4 mmol manganese chloride tetrahydrate, 60 mL water and 5 mmol urea until homogeneous, and adjust the pH to 10 to obtain a mixture.

[0057] S2. The mixture is transferred to a 100mL high-pressure reactor and subjected to hydrothermal reaction at 160℃ for 24 hours. After the reaction is completed, it is centrifuged at 4000r / min. The solid is collected, washed, and dried at 60℃ for 12 hours. Finally, it is placed in a grinding dish and ground for 10 minutes to obtain manganese-doped boehmite powder, denoted as 10%Mn-BH, where 10% is the manganese doping ratio.

[0058] S3. Add 0.5g of manganese-doped boehmite powder, 2g of polyvinylidene fluoride, and 3.75g of N-methylpyrrolidone to 0.025g of oleic acid polyethylene glycol ester in sequence, and stir at room temperature for 30 minutes to obtain manganese-doped boehmite slurry.

[0059] S4. After ultrasonically cleaning the PE microporous membrane, place it in a forced-air oven at 40°C and dry for 30 minutes. Use a 3μm wire rod coater to evenly coat both sides of the PE microporous membrane with manganese-doped boehmite slurry. Let it stand for 10 minutes, then place it in a forced-air oven at 60°C and dry for 2 hours to obtain a manganese-doped boehmite lithium-ion battery separator, denoted as Mn-BH / PE.

[0060] Example 4

[0061] A method for preparing a manganese-doped boehmite lithium-ion battery separator is similar to that in Example 1, except that the type of wire rod coating device is different, and specifically includes the following steps:

[0062] S1. At room temperature, mix 4 mmol aluminum nitrate nonahydrate, 0.08 mmol manganese chloride tetrahydrate, 60 mL water and 5 mmol urea until homogeneous, and adjust the pH to 10 to obtain a mixture.

[0063] S2. The mixture is transferred to a 100mL high-pressure reactor and subjected to hydrothermal reaction at 160℃ for 24 hours. After the reaction is completed, it is centrifuged at 4000r / min. The solid is collected, washed, and dried at 60℃ for 12 hours. Finally, it is placed in a grinding dish and ground for 10 minutes to obtain manganese-doped boehmite powder, denoted as 2%Mn-BH, where 2% is the manganese doping ratio.

[0064] S3. Add 0.5g of manganese-doped boehmite powder, 2g of polyvinylidene fluoride, and 3.75g of N-methylpyrrolidone to 0.025g of oleic acid polyethylene glycol ester in sequence, and stir at room temperature for 30 minutes to obtain manganese-doped boehmite slurry.

[0065] S4. After ultrasonically cleaning the PE microporous membrane, place it in a forced-air oven at 40°C and dry for 30 minutes. Use a 6μm wire rod coater to evenly coat both sides of the PE microporous membrane with manganese-doped boehmite slurry. Let it stand for 10 minutes, then place it in a forced-air oven at 60°C and dry for 2 hours to obtain a manganese-doped boehmite lithium-ion battery separator, denoted as Mn-BH / PE.

[0066] Example 5

[0067] A method for preparing a manganese-doped boehmite lithium-ion battery separator is similar to that in Example 2, except that the type of wire rod coating device is different, and specifically includes the following steps:

[0068] S1. At room temperature, mix 4 mmol aluminum nitrate nonahydrate, 0.2 mmol manganese chloride tetrahydrate, 60 mL water and 5 mmol urea and stir until homogeneous. Adjust the pH to 11 to obtain a mixture.

[0069] S2. The mixture is transferred to a 100mL high-pressure reactor and subjected to hydrothermal reaction at 160℃ for 24 hours. After the reaction is completed, it is centrifuged at 4000r / min. The solid is collected, washed, and dried at 60℃ for 12 hours. Finally, it is placed in a grinding dish and ground for 10 minutes to obtain manganese-doped boehmite powder, denoted as 5%Mn-BH, where 5% is the manganese doping ratio.

[0070] S3. Add 0.5g of manganese-doped boehmite powder, 2g of polyvinylidene fluoride, and 3.75g of N-methylpyrrolidone to 0.025g of oleic acid polyethylene glycol ester in sequence, and stir at room temperature for 30 minutes to obtain manganese-doped boehmite slurry.

[0071] S4. After ultrasonically cleaning the PE microporous membrane, place it in a forced-air oven at 40°C and dry for 30 minutes. Use a 6μm wire rod coater to evenly coat both sides of the PE microporous membrane with manganese-doped boehmite slurry. Let it stand for 10 minutes, then place it in a forced-air oven at 60°C and dry for 2 hours to obtain a manganese-doped boehmite lithium-ion battery separator, denoted as Mn-BH / PE.

[0072] Example 6

[0073] A method for preparing a manganese-doped boehmite lithium-ion battery separator is similar to that in Example 3, except that the type of wire rod coating device is different, and specifically includes the following steps:

[0074] S1. At room temperature, mix 4 mmol aluminum nitrate nonahydrate, 0.4 mmol manganese chloride tetrahydrate, 60 mL water and 5 mmol urea and stir until homogeneous. Adjust the pH to 10 to obtain a mixture.

[0075] S2. The mixture is transferred to a 100mL high-pressure reactor and subjected to hydrothermal reaction at 160℃ for 24 hours. After the reaction is completed, it is centrifuged at 4000r / min. The solid is collected, washed, and dried at 60℃ for 12 hours. Finally, it is placed in a grinding dish and ground for 10 minutes to obtain manganese-doped boehmite powder, denoted as 10%Mn-BH, where 10% is the manganese doping ratio.

[0076] S3. Add 0.5g of manganese-doped boehmite powder, 2g of polyvinylidene fluoride, and 3.75g of N-methylpyrrolidone to 0.025g of oleic acid polyethylene glycol ester in sequence, and stir at room temperature for 30 minutes to obtain manganese-doped boehmite slurry.

[0077] S4. After ultrasonically cleaning the PE microporous membrane, place it in a forced-air oven at 40°C and dry for 30 minutes. Use a 6μm wire rod coater to evenly coat both sides of the PE microporous membrane with manganese-doped boehmite slurry. Let it stand for 10 minutes, then place it in a forced-air oven at 60°C and dry for 2 hours to obtain a manganese-doped boehmite lithium-ion battery separator, denoted as Mn-BH / PE.

[0078] Comparative Example 1

[0079] A method for preparing a boehmite lithium-ion battery separator, similar to Example 1, except that manganese chloride is not added, specifically including the following steps:

[0080] S1. At room temperature, mix 4 mmol aluminum nitrate nonahydrate, 0.08 mmol manganese chloride tetrahydrate, 60 mL water and 5 mmol urea until homogeneous, and adjust the pH to 10 to obtain a mixture.

[0081] S2. The mixture is transferred to a 100mL high-pressure reactor and subjected to hydrothermal reaction at 160℃ for 24h. After the reaction is completed, it is centrifuged at 4000r / min, the solid is collected, washed, and dried at 60℃ for 12h. Finally, it is placed in a grinding dish and ground for 10min to obtain boehmite powder, denoted as BH.

[0082] S3. Add 0.5g boehmite powder, 2g polyvinylidene fluoride, and 3.75g N-methylpyrrolidone to 0.025g polyethylene glycol oleate in sequence, and stir at room temperature for 30 minutes to obtain boehmite slurry.

[0083] S4. After ultrasonically cleaning the PE microporous membrane, place it in a forced-air oven at 40°C and dry for 30 minutes. Use a 3μm wire rod coater to evenly coat both sides of the PE microporous membrane with boehmite slurry. Let it stand for 10 minutes, then place it in a forced-air oven at 60°C and dry for 2 hours to obtain a boehmite lithium-ion battery separator, denoted as BH / PE.

[0084] Comparative Example 2

[0085] A method for preparing a boehmite lithium-ion battery separator is similar to Comparative Example 1, except that the type of wire rod coating device is different, and specifically includes the following steps:

[0086] S1. At room temperature, mix 4 mmol aluminum nitrate nonahydrate, 0.08 mmol manganese chloride tetrahydrate, 60 mL water and 5 mmol urea until homogeneous, and adjust the pH to 10 to obtain a mixture.

[0087] S2. The mixture is transferred to a 100mL high-pressure reactor and subjected to hydrothermal reaction at 160℃ for 24h. After the reaction is completed, it is centrifuged at 4000r / min, the solid is collected, washed, and dried at 60℃ for 12h. Finally, it is placed in a grinding dish and ground for 10min to obtain boehmite powder, denoted as BH.

[0088] S3. Add 0.5g boehmite powder, 2g polyvinylidene fluoride, and 3.75g N-methylpyrrolidone to 0.025g polyethylene glycol oleate in sequence, and stir at room temperature for 30 minutes to obtain boehmite slurry.

[0089] S4. After ultrasonically cleaning the PE microporous membrane, place it in a forced-air oven at 40°C and dry for 30 minutes. Use a 6μm wire rod coater to evenly coat both sides of the PE microporous membrane with boehmite slurry. Let it stand for 10 minutes, then place it in a forced-air oven at 60°C and dry for 2 hours to obtain a boehmite lithium-ion battery separator, denoted as BH / PE.

[0090] The XRD patterns of Mn-BH with different manganese doping ratios obtained in Comparative Example 1 and Examples 1-3 of this invention are as follows: Figure 2 As shown in the figure, typical γ-AlOOH (boehmite) diffraction peaks (JCPDS standard card 21-1307) can be observed, with the main peak positions corresponding to crystal planes such as (020), (120), and (031). With the increase of manganese doping ratio (2%→10%), some diffraction peaks (such as (020)) may slightly shift, indicating that manganese ions (Mn)... 2+ / Mn 3+ It may enter the boehmite lattice, causing a small change in lattice parameters (such as an increase in interlayer spacing);

[0091] High manganese doping (10%) may lead to a slight broadening of diffraction peaks, reflecting lattice distortion or a reduction in nanocrystal size. The absence of obvious characteristic peaks for manganese oxides such as MnO and Mn2O3 in the spectrum suggests that manganese may be substituted for Al. 3+ Mn 2+ / Mn 3+ It exists in the form of substitution or interlayer adsorption, rather than as an independent phase;

[0092] Manganese doping did not disrupt the boehmite matrix structure, thus ensuring the mechanical strength of the membrane. Lattice micro-expansion (peak shift) may provide a more relaxed Li... + Migration channels. Manganese doping sites (replacing Al) 3+ It may introduce additional charge carriers, thereby increasing conductivity.

[0093] The SEM images of BH obtained in Comparative Example 1 and the SEM images of Mn-BH with different manganese doping ratios obtained in Examples 1-3 are as follows: Figure 3 The above; wherein, Figure 3 b is the SEM image of BH obtained from Comparative Example 1. Figure 3 c-3e are SEM images of Mn-BH with different manganese doping ratios obtained in Examples 1, 2, and 3, respectively. The images show a typical boehmite nanosheet / nanofiber structure with a clear two-dimensional layered stacking morphology, smooth surface, and relatively uniform particle size. The SEM image of the low-manganese-doped (2%) Mn-BH is shown below. Figure 3As shown in c, the morphology is similar to that of pure BH, but the edges of the nanosheets show slight roughening, possibly due to surface defects caused by manganese ions partially substituting aluminum sites. The SEM image of 5% Mn-BH is shown below. Figure 3 As shown in d, the nanosheet size is slightly reduced, and the stacking density increases, forming a denser porous structure. The SEM image of the 10% Mn-BH nanosheet is shown below. Figure 3 As shown in Figure e, its morphology has changed significantly. The nanosheets are thinner and partially curled, with more pores and cracks appearing, which may be related to lattice distortion caused by high manganese doping.

[0094] Among them, the rough surface and porous structure of Mn-BH with manganese doping of 5% and 10% increase the contact area with the electrolyte and reduce the interfacial impedance. Figure 3 The densely stacked nanosheets shown in diagram d may form continuous lithium-ion channels, while Figure 3 The high-manganese-doped pores shown in e provide a rapid diffusion path, which together enhances the conductivity.

[0095] Conductivity Testing: The boehmite lithium-ion battery separators obtained in Examples 1-6 and Comparative Examples 1-2 were used to assemble blocked batteries. The assembly sequence was: negative electrode shell, stainless steel sheet, separator, electrolyte, stainless steel sheet, spring contact, and positive electrode shell. After assembly, the ionic conductivity was tested using a CHI660E electrochemical workstation in AC impedance mode at a frequency of 0.1-10 Hz. 6 Hz, and finally the ionic conductivity was calculated according to the formula. The test results are shown in Table 1:

[0096] Table 1. Conductivity test results of the assembled blocking battery

[0097] <![CDATA[Ionic conductivity (ms·cm -1 )]]> Example 1 0.481 Example 2 0.514 Example 3 0.592 Example 4 0.854 Example 5 0.928 Example 6 1.152 Comparative Example 1 0.314 Comparative Example 2 0.383

[0098] As can be seen from the experimental results in Table 1, the manganese content in boehmite and different coating thicknesses can improve the ionic conductivity of the boehmite lithium-ion battery separator. From the experimental results of Examples 1-3 and Comparative Example 1, it can be seen that as the manganese content in boehmite increases, the ionic conductivity of the boehmite lithium-ion battery separator (Mn-BH / PE) shows a gradually increasing trend. By comparing the experimental results of Examples 4-6 with those of Examples 1-3, the ionic conductivity of the boehmite lithium-ion battery separator prepared in Examples 4-6 of this invention is significantly improved, proving that the ionic conductivity shows a gradually increasing trend as the separator thickness increases.

[0099] Wetting performance test: The test object was the manganese-doped boehmite lithium-ion battery separator obtained in Comparative Example 1 and Examples 1-3. A contact angle meter was used to drop lithium-ion electrolyte onto the surface of the test sample, and the contact angle data was recorded. The wetting performance of the separator was evaluated by the contact angle of the lithium-ion electrolyte on the separator. A low contact angle (good wettability) means that the electrolyte can quickly penetrate the separator pores, forming a uniform electrolyte channel, reducing lithium-ion transport resistance, allowing the electrolyte to fully wet the separator and electrodes, forming a stable solid electrolyte interface (SEI) film, reducing side reactions (such as electrolyte decomposition), and delaying capacity decay. The test results are as follows: Figure 4 As shown, by Figure 4 It can be seen that as the content of manganese doping in boehmite increases, the contact angle of the manganese-doped boehmite composite membrane (Mn-BH / PE) gradually decreases, indicating that the hydroxyl density on the surface of the doped boehmite is increased, thereby improving the wettability of the manganese-doped boehmite composite membrane.

[0100] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A manganese-doped boehmite lithium-ion battery separator, characterized in that, It includes a base film and a manganese-doped boehmite coating located on the surface of the base film; wherein the manganese-doped boehmite coating includes the following raw materials: manganese-doped boehmite, organic polymer binder, dispersant, and organic solvent.

2. The manganese-doped boehmite lithium-ion battery separator according to claim 1, characterized in that: The base film is a PE film.

3. A method for preparing a manganese-doped boehmite lithium-ion battery separator according to claim 1, characterized in that, Includes the following steps: S1. Add manganese-doped boehmite, organic polymer binder, and dispersant to an organic solvent in sequence, and mix and stir evenly to obtain manganese-doped boehmite slurry; S2. Coat the base film with manganese-doped boehmite slurry and dry it to obtain a manganese-doped boehmite lithium-ion battery separator.

4. The preparation method according to claim 3, characterized in that: The preparation method of manganese-doped boehmite in step S1 is as follows: S3. Mix aluminum salt, manganese salt, water and alkaline precipitant evenly, adjust the pH value to 10-11 to obtain a mixed solution; S4. The mixture is transferred to a high-pressure reactor for hydrothermal reaction. After the reaction is completed, the mixture is centrifuged, the solid is collected, washed, dried, and ground to obtain manganese-doped boehmite.

5. The preparation method according to claim 4, characterized in that: The aluminum salt in step S3 is aluminum nitrate nonahydrate; the manganese salt is either manganese chloride or manganese nitrate; and the alkaline precipitant is urea.

6. The preparation method according to claim 5, characterized in that: The molar ratio of the aluminum salt, manganese salt, and alkaline precipitant is 1:0.02-0.1:1.25-1.

3.

7. The preparation method according to claim 3, characterized in that: In step S1, the mass ratio of manganese-doped boehmite to organic polymer binder is 2-3:7-8.

8. The manganese-doped boehmite lithium-ion battery separator according to claim 1, characterized in that: The organic polymer adhesive is polyvinylidene fluoride.

9. The manganese-doped boehmite lithium-ion battery separator according to claim 1, characterized in that: The organic solvent is N-methylpyrrolidone.

10. A lithium-ion battery, characterized in that: Includes the manganese-doped boehmite lithium-ion battery separator as described in claim 1.

Images