A low temperature lithium battery separator material containing nanoceramic material

Abstract

The application relates to the technical field of battery diaphragm, and discloses a low-temperature lithium battery diaphragm material containing nano ceramic materials, and a preparation method thereof, which comprises the following preparation steps: mixing modified nano ceramic materials, modified sheet layer graphene oxide, a binder and deionized water to obtain a mixed slurry; spraying the mixed slurry onto the upper and lower surfaces of a polyolefin diaphragm, and drying and curing to obtain a lithium battery diaphragm material. The modified nano ceramic materials and the modified sheet layer graphene oxide are coated on the polyolefin diaphragm, and the prepared lithium battery diaphragm material has high temperature resistance and mechanical properties.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of battery separator membranes, in particular to a low-temperature lithium battery separator membrane material containing nano ceramic materials. BACKGROUND

[0002] In the structure of a lithium ion battery, a separator membrane, as an inner layer component, can separate the positive and negative electrodes of the battery, prevent the two electrodes from contacting and short-circuiting, and allow ions to transmit in the battery, thereby improving the comprehensive performance of the lithium ion battery, such as the capacity, cycle and safety performance of the battery, and the separator membrane material used in the lithium ion battery is mainly based on a polyolefin film, such as a polypropylene separator membrane, a polyethylene separator membrane and a polytetrafluoroethylene separator membrane.

[0003] The polyolefin film can improve the electrochemical performance of the lithium ion battery as the lithium battery separator membrane material, but the polyolefin separator membrane material has poor temperature resistance, is prone to shrinkage or melting rupture when heated, and the pores of the separator membrane are prone to collapse and shrink at low temperatures, which leads to internal short circuit of the lithium battery and affects the electrochemical performance of the lithium battery; the nano ceramic material is coated on the surface of the polyolefin film through a binder, which can improve the high-temperature resistance of the lithium battery separator membrane material, but the nano ceramic material is prone to agglomeration, which affects the electrochemical performance of the lithium battery, and in addition, the polyolefin film also has the defect of poor mechanical performance. SUMMARY

[0004] The application provides a low-temperature lithium battery separator membrane material containing nano ceramic materials, and solves the problems of poor temperature resistance of the lithium battery separator membrane material and agglomeration of the nano ceramic material on the surface of the separator membrane.

[0005] The technical scheme of the application is as follows:

[0006] A low-temperature lithium battery separator membrane material containing nano ceramic materials, and a preparation method thereof, the preparation method comprising the following preparation steps:

[0007] S1. mixing modified nano ceramic materials, modified layered graphene oxide, a binder and deionized water to obtain a mixed slurry;

[0008] S2. spraying the mixed slurry onto the upper and lower surfaces of a polyolefin separator membrane, and drying and curing to obtain a lithium battery separator membrane material;

[0009] The modified nano ceramic material is obtained by synthesizing porous carbon on the surface of nano ceramic materials and then depositing the porous carbon on the surface of polydopamine-modified silicon carbide whiskers.

[0010] The modified layered graphene oxide is obtained by modifying the layered graphene oxide with tannic acid on the surface, and then mixing and reacting the modified layered graphene oxide with a zinc source and dimethyl imidazole.

[0011] Further, in step S1, the mass ratio of the modified nanoceramic material, the modified sheet layer graphene oxide, the binder and the deionized water is (20-25):(10-15):(0.5-1):(40-60).

[0012] Further, in step S2, the spraying amount of the mixed slurry on the upper surface and the lower surface of the polyolefin separator is 18-22 g / m 2 , and the spraying pressure is 0.3-0.5 MPa.

[0013] Further, in step S2, the polyolefin separator is selected from any one of a polypropylene separator, a polyethylene separator and a polytetrafluoroethylene separator.

[0014] Further, in step S2, the drying and curing temperature is 40-60℃, and the time is 30-50 min.

[0015] Further, the thickness of the polyolefin separator is 10-15 μm.

[0016] Further, the thickness of the lithium battery separator material is 30-40 μm.

[0017] Further, the modified nanoceramic material is prepared by the following steps:

[0018] A1. The nanoceramic material, glucose and citric acid are added to ethanol, stirred uniformly, hydrochloric acid is added, stirred and reacted, filtered, washed, dried, mixed with potassium hydroxide solution, nitrogen is introduced, carbonized at 750-850℃ for 3-5h, cooled to room temperature, taken out, washed, dried, and the nanoceramic material loaded with porous carbon is obtained;

[0019] A2. The silicon carbide whisker is added to Tris-HCl buffer solution, stirred uniformly, dopamine is added, stirred and reacted, filtered, washed, dried, and the polydopamine modified silicon carbide whisker is obtained;

[0020] A3. The polydopamine modified silicon carbide whisker and the nanoceramic material loaded with porous carbon are added to deionized water, stirred, and after standing, filtered, washed, and dried, the modified nanoceramic material is obtained.

[0021] Further, in the above A1 reaction process, the large number of hydroxyl groups contained in citric acid can be combined with the nanoceramic material through hydrogen bonds, and citric acid can also be combined with glucose through chemical bonds, so that glucose is adhered to the surface of the nanoceramic material through citric acid, and after high-temperature carbonization, glucose is decomposed by heat to form a dense carbon layer. The potassium hydroxide solution acts as an activator and can form pores on the surface of the dense carbon layer, so as to synthesize a porous carbon structure on the surface of the nanoceramic material, and obtain the nanoceramic material loaded with porous carbon.

[0022] Further, in the A2 reaction process, dopamine can self-polymerize on the surface of the silicon carbide whisker to form polydopamine in the Tris-HCl buffer solution, so that the silicon carbide whisker carries a large number of phenolic hydroxyl groups, and the polydopamine modified silicon carbide whisker is obtained, which improves the surface activity of the silicon carbide whisker and is beneficial to the deposition of the porous carbon loaded nanoceramic material on the surface of the silicon carbide whisker.

[0023] Further, in the A3 reaction process, the polydopamine modified silicon carbide whisker has excellent adhesion and contains a large number of phenolic hydroxyl groups, so that the porous carbon loaded nanoceramic material adheres to the surface of the polydopamine modified silicon carbide whisker, and the modified nanoceramic material is obtained.

[0024] Further, in step A1, the amount ratio of the nanoceramic material, glucose, citric acid, ethanol, hydrochloric acid and potassium hydroxide solution is (5-6) g:(3-4) g:(0.5-0.7) g:(80-120) mL:(0.4-0.6) mL:(4-6) mL.

[0025] Further, in step A2, the amount ratio of the silicon carbide whisker, Tris-HCl buffer solution and dopamine is (5.1-5.5) g:(75-85) mL:(0.5-0.7) g.

[0026] Further, in step A3, the amount ratio of the polydopamine modified silicon carbide whisker, the porous carbon loaded nanoceramic material and deionized water is (4-5) g:(3-3.6) g:(90-110) mL.

[0027] Further, the nanoceramic material is selected from any one of aluminum oxide particles, silicon dioxide particles and titanium dioxide particles.

[0028] Further, the particle size of the nanoceramic material is 400-600 nm.

[0029] Further, the diameter of the silicon carbide whisker is 1-2 µm, and the length is 10-50 µm.

[0030] Further, the modified layered graphene oxide is prepared by the following steps:

[0031] B1. Tannic acid is added to ethanol, stirred until completely dissolved, layered graphene oxide is added, stirred uniformly, filtered, washed, dried, and tannic acid modified layered graphene oxide is obtained;

[0032] B2. Zinc nitrate hexahydrate, 2-amino benzothiazole and 2-methyl imidazole are added into methanol, stirred uniformly, sodium formate and tannic acid modified sheet layer graphene oxide are added, stirred uniformly, nitrogen is introduced, and the reaction is carried out at 60-70 DEG C for 3-5 h, the precipitate is collected by centrifugation, the precipitate is washed and dried, and the modified sheet layer graphene oxide is obtained.

[0033] Further, in the above B1 reaction process, the tannic acid contains a large amount of phenolic hydroxyl groups, has good adhesion, and can be combined with the hydroxyl groups on the surface of the sheet layer graphene oxide through chemical bonds, so that the tannic acid is coated on the surface of the sheet layer graphene oxide to obtain the tannic acid modified sheet layer graphene oxide.

[0034] Further, in the above B1 reaction process, the zinc ions in the zinc nitrate hexahydrate can be combined with the oxygen-containing functional groups on the surface of the tannic acid modified sheet layer graphene oxide, so that the zinc ions are deposited on the surface of the tannic acid modified sheet layer graphene oxide, and the 2-methyl imidazole and 2-amino benzothiazole act as organic ligands, the zinc ions react with the organic ligands to form a three-dimensional network structure of zinc-based metal organic skeleton, so that the zinc-based metal organic skeleton is deposited on the surface of the tannic acid modified sheet layer graphene oxide to obtain the modified sheet layer graphene oxide.

[0035] Further, in step B1, the amount ratio of tannic acid, ethanol and sheet layer graphene oxide is (0.6-1) g:(45-55) mL:(2-2.4) g.

[0036] Further, in step B2, the amount ratio of zinc nitrate hexahydrate, 2-amino benzothiazole, 2-methyl imidazole, methanol, sodium formate and tannic acid modified sheet layer graphene oxide is (1.5-2.5) g:(1.6-2) g:(2.5-2.9) g:(75-85) mL:(1.3-1.7) g:(5.5-5.9) g.

[0037] Further, the thickness of the sheet layer graphene oxide is 1-1.5 nm, and the sheet diameter is 1-2 µm.

[0038] A low-temperature lithium battery diaphragm material containing nano ceramic material is prepared by the above-mentioned method for preparing lithium battery diaphragm material.

[0039] The present application has the following beneficial effects:

[0040] (1) In the technical scheme of the present application, porous carbon structure is synthesized on the surface of nanoceramic material. On the one hand, the synthesized porous carbon has high pore structure and pore capacity, accelerates the transmission performance of lithium ions, enhances the migration rate of lithium ions, improves the electrochemical performance, and synthesizes porous carbon on the surface of nanoceramic material to improve the roughness of the surface of nanoceramic material, increase the contact area of nanoceramic material and electrolyte, improve the migration number of lithium ions, on the other hand, the porous carbon and nanoceramic material as the coating of the separator have high heat resistance and low temperature resistance, improve the thermal shrinkage rate of the lithium battery separator material, and the nanoceramic material loaded with porous carbon can hinder the hole shrinkage collapse of the separator at low temperature, so that the separator still maintains the lithium ion transmission performance at low temperature, in addition, the nanoceramic material loaded with porous carbon adheres to the surface of the separator, forms small pores on the surface layer provided by the porous carbon to inhibit low temperature dendrite, and the large pores of the bottom layer of the separator store electrolyte, which guarantees the low temperature ion transmission.

[0041] (2) In the technical scheme of the present application, the silicon carbide whisker is modified by using polydopamine to improve the surface activity of the silicon carbide whisker, which is beneficial to the deposition of the nanoceramic material loaded with porous carbon on the surface of the silicon carbide whisker. On the one hand, the silicon carbide whisker modified by polydopamine serves as a carrier of the nanoceramic material loaded with porous carbon, avoids the agglomeration of the nanoceramic material loaded with porous carbon, and affects the transmission of lithium ions by the separator, and the silicon carbide whisker has excellent aspect ratio and is distributed randomly on the surface of the separator to form a network structure capable of absorbing and weakening external force, thereby improving the mechanical properties of the separator. On the other hand, the silicon carbide whisker has good low temperature resistance, so that the separator has good lithium ion transmission performance at low temperature. In addition, the silicon carbide whisker surface contains porous carbon, which can form a lithium ion transmission channel on the surface of the separator, shorten the lithium ion transmission path, and improve the charge and discharge efficiency of the lithium ion battery.

[0042] (3) In the technical scheme of the present application, the layered graphene oxide is surface modified by tannic acid, which is beneficial to the synthesis of zinc-based metal organic framework on the surface of the layered graphene oxide, and the coating on the surface of the separator improves the lithium ion transmission performance, temperature resistance and mechanical properties of the separator. On the one hand, the synthesized zinc-based metal organic framework has high adsorption performance for lithium ions, improves the enrichment of lithium ions on the surface of the separator, shortens the distance of lithium ion diffusion from the electrolyte to the electrode, improves the transmission performance of lithium ions, and the layered graphene oxide serves as a carrier of the zinc-based metal organic framework, so that the zinc-based metal organic framework is well dispersed on the surface of the separator. On the other hand, the layered graphene oxide has high low temperature resistance, which enhances the low temperature lithium ion transmission performance of the separator. The layered graphene oxide can withstand external load by interpenetrating each other, which significantly improves the mechanical properties of the lithium battery separator. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0044] The raw materials used in the embodiments of the present application are shown below, and all the reagents used are analytical grade.

[0045] The polyolefin separator is a polypropylene separator, and the polypropylene film is purchased from Xinxiang City Zhongke Technology Co., Ltd.

[0046] The binder is carboxymethyl cellulose.

[0047] The nano ceramic material is an alumina particle with a particle size of 500 nm.

[0048] The silicon carbide whisker has a diameter of 1.5 µm and a length of 35 µm.

[0049] The sheet layer of graphene oxide has a thickness of 1.2 nm and a sheet diameter of 1.5 µm.

[0050] Embodiment 1

[0051] A low-temperature lithium battery separator material containing a nano ceramic material, and a preparation method thereof, includes the following preparation steps:

[0052] S1. Mixing the modified nano ceramic material, the modified sheet layer of graphene oxide, the carboxymethyl cellulose and the deionized water to obtain a mixed slurry;

[0053] S2. Spraying the mixed slurry onto the upper and lower surfaces of the polypropylene separator, and drying and curing at 40℃ for 50 min to obtain a lithium battery separator material.

[0054] In step S1, the mass ratio of the modified nano ceramic material, the modified sheet layer of graphene oxide, the carboxymethyl cellulose and the deionized water is 20:10:0.5:40;

[0055] In step S2, the spraying amount of the mixed slurry onto the upper and lower surfaces of the polypropylene separator is 18 g / m 2 , and the spraying pressure is 0.3 MPa;

[0056] The thickness of the polypropylene separator is 10 µm, and the thickness of the lithium battery separator material is 30 µm.

[0057] The modified nano ceramic material is prepared by the following steps:

[0058] A1. 5 g of nanoceramic material, 3 g of glucose and 0.5 g of citric acid were added to 80 mL of ethanol, stirred until uniform, 0.4 mL of 36% hydrochloric acid was added, stirred at 70°C for 35 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, placed in a tube furnace, 4 mL of 30% potassium hydroxide solution was added, nitrogen was introduced, the nitrogen flow rate was 30 mL / min, the temperature was raised to 750°C, carbonization was carried out for 3 h, the heating rate was 10°C / min, cooled to room temperature, taken out, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain a nanoceramic material loaded with porous carbon;

[0059] A2. 5.1 g of silicon carbide whiskers were added to 75 mL of Tris-HCl buffer with pH of 8.5, stirred until uniform, 0.5 g of dopamine was added, stirred at 25°C, 800 r / min for 3.5 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain polydopamine modified silicon carbide whiskers;

[0060] A3. 4 g of polydopamine modified silicon carbide whiskers and 3 g of nanoceramic material loaded with porous carbon were added to 90 mL of deionized water, stirred at 900 r / min for 25 min, stood for 1 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain modified nanoceramic material.

[0061] The modified layered graphene oxide was prepared by the following steps:

[0062] B1. 0.6 g of tannic acid was added to 45 mL of ethanol, stirred until completely dissolved, 2 g of layered graphene oxide was added, stirred at 50°C for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain tannic acid modified layered graphene oxide;

[0063] B2. 1.5 g of zinc nitrate hexahydrate, 1.6 g of 2-amino benzothiazole and 2.5 g of 2-methyl imidazole were added to 75 mL of methanol, stirred until uniform, 1.3 g of sodium formate and 5.5 g of tannic acid modified layered graphene oxide were added, stirred until uniform, nitrogen was introduced, reacted at 60°C for 3 h, centrifuged at a speed of 8000 r / min, washed with methanol for 3 times, washed with deionized water for 3 times, dried in an oven at 60°C for 10 min, to obtain modified layered graphene oxide.

[0064] Example 2

[0065] A low-temperature lithium battery separator material containing nanoceramic material, the preparation method comprising the following preparation steps:

[0066] S1. mixing the modified nanoceramic material, the modified layered graphene oxide, carboxymethyl cellulose and deionized water to obtain a mixed slurry;

[0067] S2. spraying the mixed slurry onto the upper and lower surfaces of the polypropylene separator, drying and curing at 50℃ for 40min to obtain a lithium battery separator material.

[0068] In step S1, the mass ratio of the modified nanoceramic material, the modified layered graphene oxide, carboxymethyl cellulose and deionized water is 23:13:0.8:50;

[0069] In step S2, the spraying amount of the mixed slurry onto the upper and lower surfaces of the polypropylene separator is 20g / m 2 , and the spraying pressure is 0.4MPa;

[0070] The thickness of the polypropylene separator is 13μm, and the thickness of the lithium battery separator material is 35μm.

[0071] The modified nanoceramic material is prepared by the following steps:

[0072] A1. adding 5.5g of nanoceramic material, 3.5g of glucose and 0.6g of citric acid into 100mL of ethanol, stirring uniformly, adding 0.5mL of 36% hydrochloric acid, stirring and reacting at 70℃ for 35min, filtering, washing with deionized water for 3 times, drying in a 70℃ oven for 10min, placing in a tube furnace, adding 5mL of 30% potassium hydroxide solution, passing nitrogen gas with a flow rate of 30mL / min, heating to 800℃, carbonizing for 4h with a heating rate of 10℃ / min, cooling to room temperature, taking out, washing with deionized water for 3 times, drying in a 70℃ oven for 10min to obtain a nanoceramic material loaded with porous carbon;

[0073] A2. adding 5.3g of silicon carbide whiskers into 80mL of Tris-HCl buffer solution with a pH of 8.5, stirring uniformly, adding 0.6g of dopamine, stirring and reacting at 25℃ and 800r / min for 3.5h, filtering, washing with deionized water for 3 times, drying in a 70℃ oven for 10min to obtain polydopamine modified silicon carbide whiskers;

[0074] A3. adding 4.5g of polydopamine modified silicon carbide whiskers and 3.3g of nanoceramic material loaded with porous carbon into 100mL of deionized water, stirring at 900r / min for 25min, standing for 1h, filtering, washing with deionized water for 3 times, drying in a 70℃ oven for 10min to obtain a modified nanoceramic material.

[0075] The modified layered graphene oxide is prepared by the following steps:

[0076] B1. 0.8 g of tannic acid was added to 50 mL of ethanol, stirred until completely dissolved, 2.2 g of sheet-like graphene oxide was added, stirred at 50°C for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain tannic acid modified sheet-like graphene oxide;

[0077] B2. 2 g of zinc nitrate hexahydrate, 1.8 g of 2-amino benzothiazole and 2.7 g of 2-methyl imidazole were added to 80 mL of methanol, stirred uniformly, 1.5 g of sodium formate and 5.7 g of tannic acid modified sheet-like graphene oxide were added, stirred uniformly, nitrogen was introduced, reacted at 65°C for 4 h, centrifuged at a speed of 8000 r / min, washed with methanol for 3 times, washed with deionized water for 3 times, dried in an oven at 60°C for 10 min, to obtain modified sheet-like graphene oxide.

[0078] Example 3

[0079] A low-temperature lithium battery separator material containing nanoceramic material, the preparation method comprises the following preparation steps:

[0080] S1. The modified nanoceramic material, the modified sheet-like graphene oxide, the carboxymethyl cellulose and the deionized water are mixed to obtain a mixed slurry;

[0081] S2. The mixed slurry is sprayed onto the upper and lower surfaces of the polypropylene separator, and is dried and cured at 60°C for 30 min to obtain a lithium battery separator material.

[0082] In step S1, the mass ratio of the modified nanoceramic material, the modified sheet-like graphene oxide, the carboxymethyl cellulose and the deionized water is 25:15:1:60;

[0083] In step S2, the spraying amount of the mixed slurry on the upper surface and the lower surface of the polypropylene separator is 22 g / m 2 , and the spraying pressure is 0.5 MPa;

[0084] The thickness of the polypropylene separator is 15 μm, and the thickness of the lithium battery separator material is 40 μm.

[0085] The modified nanoceramic material is prepared by the following steps:

[0086] A1. 6 g of nanoceramic material, 4 g of glucose and 0.7 g of citric acid were added to 120 mL of ethanol, stirred until uniform, 0.6 mL of 36% hydrochloric acid was added, stirred at 70°C for 35 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, placed in a tube furnace, 6 mL of 30% potassium hydroxide solution was added, nitrogen was introduced, the nitrogen flow rate was 30 mL / min, the temperature was raised to 850°C, carbonization was carried out for 5 h, the heating rate was 10°C / min, cooled to room temperature, taken out, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain a nanoceramic material loaded with porous carbon;

[0087] A2. 5.5 g of silicon carbide whiskers were added to 85 mL of Tris-HCl buffer with pH of 8.5, stirred until uniform, 0.7 g of dopamine was added, stirred at 25°C, 800 r / min for 3.5 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain polydopamine modified silicon carbide whiskers;

[0088] A3. 5 g of polydopamine modified silicon carbide whiskers and 3.6 g of nanoceramic material loaded with porous carbon were added to 110 mL of deionized water, stirred at 900 r / min for 25 min, stood for 1 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain modified nanoceramic material.

[0089] The modified layered graphene oxide was prepared by the following steps:

[0090] B1. 1 g of tannic acid was added to 55 mL of ethanol, stirred until completely dissolved, 2.4 g of layered graphene oxide was added, stirred at 50°C for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain tannic acid modified layered graphene oxide;

[0091] B2. 2.5 g of zinc nitrate hexahydrate, 2 g of 2-amino benzothiazole and 2.9 g of 2-methyl imidazole were added to 85 mL of methanol, stirred until uniform, 1.7 g of sodium formate and 5.9 g of tannic acid modified layered graphene oxide were added, stirred until uniform, nitrogen was introduced, reacted at 70°C for 5 h, centrifuged at a speed of 8000 r / min, washed with methanol for 3 times, washed with deionized water for 3 times, dried in an oven at 60°C for 10 min, to obtain modified layered graphene oxide.

[0092] Comparative Example 1

[0093] A low-temperature lithium battery diaphragm material containing nanoceramic material, the preparation method comprises the following preparation steps:

[0094] S1. Mix the modified nanoceramic material, modified layered graphene oxide, carboxymethyl cellulose, and deionized water to obtain a mixed slurry;

[0095] S2. Spray the mixed slurry onto the upper and lower surfaces of the polypropylene separator, and dry and cure at 60°C for 30 min to obtain a lithium battery separator material.

[0096] In step S1, the mass ratio of the modified nanoceramic material, modified layered graphene oxide, carboxymethyl cellulose, and deionized water is 25:15:1:60;

[0097] In step S2, the spraying amount of the mixed slurry onto the upper and lower surfaces of the polypropylene separator is 22 g / m 2 , and the spraying pressure is 0.5 MPa;

[0098] The thickness of the polypropylene separator is 15 μm, and the thickness of the lithium battery separator material is 40 μm.

[0099] The modified nanoceramic material is prepared by the following steps:

[0100] A1. Add 5.5 g of silicon carbide whiskers to 85 mL of Tris-HCl buffer with a pH of 8.5, stir until uniform, add 0.7 g of dopamine, stir at 25°C and 800 r / min for 3.5 h, filter, wash with deionized water 3 times, and dry in a 70°C oven for 10 min to obtain polydopamine-modified silicon carbide whiskers;

[0101] A2. Add 5 g of polydopamine-modified silicon carbide whiskers and 3.6 g of nanoceramic material to 110 mL of deionized water, stir at 900 r / min for 25 min, stand for 1 h, filter, wash with deionized water 3 times, and dry in a 70°C oven for 10 min to obtain a modified nanoceramic material.

[0102] The modified layered graphene oxide is prepared by the following steps:

[0103] B1. Add 1 g of tannic acid to 55 mL of ethanol, stir until completely dissolved, add 2.4 g of layered graphene oxide, stir at 50°C for 30 min, filter, wash with deionized water 3 times, and dry in a 70°C oven for 10 min to obtain tannic acid-modified layered graphene oxide;

[0104] B2. 2.5 g of zinc nitrate hexahydrate, 2 g of 2-amino benzothiazole and 2.9 g of 2-methyl imidazole were added into 85 mL of methanol, stirred uniformly, 1.7 g of sodium formate and 5.9 g of tannic acid modified sheet layer graphene oxide were added, stirred uniformly, nitrogen was introduced, reacted at 70°C for 5 h, centrifuged at a speed of 8000 r / min, washed with methanol for 3 times, deionized water for 3 times, dried in an oven at 60°C for 10 min, to obtain the modified sheet layer graphene oxide.

[0105] Comparative Example 2

[0106] A low-temperature lithium battery diaphragm material containing a nano ceramic material, and a preparation method thereof, comprising the following preparation steps:

[0107] S1. The modified nano ceramic material, the modified sheet layer graphene oxide, the carboxymethyl cellulose and the deionized water were mixed to obtain a mixed slurry;

[0108] S2. The mixed slurry was sprayed onto the upper and lower surfaces of the polypropylene diaphragm, and was dried and cured at 60°C for 30 min to obtain a lithium battery diaphragm material.

[0109] In step S1, the mass ratio of the modified nano ceramic material, the modified sheet layer graphene oxide, the carboxymethyl cellulose and the deionized water is 25:15:1:60;

[0110] In step S2, the spraying amount of the mixed slurry on the upper surface and the lower surface of the polypropylene diaphragm is 22 g / m 2 , and the spraying pressure is 0.5 MPa;

[0111] The thickness of the polypropylene diaphragm is 15 μm, and the thickness of the lithium battery diaphragm material is 40 μm.

[0112] The modified nano ceramic material is prepared by the following steps:

[0113] A1. 6 g of nano ceramic material, 4 g of glucose and 0.7 g of citric acid were added into 120 mL of ethanol, stirred uniformly, 0.6 mL of 36% hydrochloric acid was added, stirred and reacted at 70°C for 35 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, placed in a tube furnace, 6 mL of 30% potassium hydroxide solution was added, nitrogen was introduced, the nitrogen flow was 30 mL / min, the temperature was raised to 850°C, carbonization was carried out for 5 h, the temperature rising rate was 10°C / min, cooled to room temperature, taken out, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain the nano ceramic material loaded with porous carbon;

[0114] A2. 5 g of silicon carbide whiskers and 3.6 g of porous carbon loaded nanoceramic material were added into 110 mL of deionized water, stirred at 900 r / min for 25 min, and after standing for 1 h, filtered, washed with deionized water for 3 times, and dried in an oven at 70 DEG C for 10 min to obtain the modified nanoceramic material.

[0115] The modified sheet layer graphene oxide was prepared by the following steps:

[0116] B1. 1 g of tannic acid was added into 55 mL of ethanol, stirred until completely dissolved, 2.4 g of sheet layer graphene oxide was added, stirred at 50 DEG C for 30 min, filtered, washed with deionized water for 3 times, and dried in an oven at 70 DEG C for 10 min to obtain the sheet layer graphene oxide modified by tannic acid;

[0117] B2. 2.5 g of zinc nitrate hexahydrate, 2 g of 2-amino benzothiazole and 2.9 g of 2-methyl imidazole were added into 85 mL of methanol, stirred until uniform, 1.7 g of sodium formate and 5.9 g of the sheet layer graphene oxide modified by tannic acid were added, stirred until uniform, nitrogen was introduced, reacted at 70 DEG C for 5 h, centrifuged at a speed of 8000 r / min, washed with methanol for 3 times, washed with deionized water for 3 times, and dried in an oven at 60 DEG C for 10 min to obtain the modified sheet layer graphene oxide.

[0118] Comparative Example 3

[0119] A low-temperature lithium battery separator material containing nanoceramic material, and a preparation method thereof, includes the following preparation steps:

[0120] S1. The modified nanoceramic material, the modified sheet layer graphene oxide, carboxymethyl cellulose and deionized water were mixed to obtain a mixed slurry;

[0121] S2. The mixed slurry was sprayed onto the upper and lower surfaces of the polypropylene separator, and dried and cured at 60 DEG C for 30 min to obtain the lithium battery separator material.

[0122] In step S1, the mass ratio of the modified nanoceramic material, the modified sheet layer graphene oxide, carboxymethyl cellulose and deionized water was 25:15:1:60;

[0123] In step S2, the spraying amount of the mixed slurry on the upper surface and the lower surface of the polypropylene separator was 22 g / m 2 , and the spraying pressure was 0.5 MPa;

[0124] The thickness of the polypropylene separator was 15 μm, and the thickness of the lithium battery separator material was 40 μm.

[0125] The modified nanoceramic material was prepared by the following steps:

[0126] A1. 6 g of nanoceramic material, 4 g of glucose and 0.7 g of citric acid were added to 120 mL of ethanol, stirred until uniform, 0.6 mL of 36% hydrochloric acid was added, stirred at 70°C for 35 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, placed in a tube furnace, 6 mL of 30% potassium hydroxide solution was added, nitrogen was introduced, the nitrogen flow rate was 30 mL / min, the temperature was raised to 850°C, carbonization was carried out for 5 h, the heating rate was 10°C / min, cooled to room temperature, taken out, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain a nanoceramic material loaded with porous carbon;

[0127] A2. 5.5 g of silicon carbide particles (particle size 2 µm, purchased from Rizhao Hengqiao Trade Co., Ltd.) were added to 85 mL of Tris-HCl buffer with pH 8.5, stirred until uniform, 0.7 g of dopamine was added, stirred at 25°C, 800 r / min for 3.5 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain polydopamine modified silicon carbide particles;

[0128] A3. 5 g of polydopamine modified silicon carbide particles and 3.6 g of nanoceramic material loaded with porous carbon were added to 110 mL of deionized water, stirred at 900 r / min for 25 min, stood for 1 h, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain modified nanoceramic material.

[0129] The modified layered graphene oxide was prepared by the following steps:

[0130] B1. 1 g of tannic acid was added to 55 mL of ethanol, stirred until completely dissolved, 2.4 g of layered graphene oxide was added, stirred at 50°C for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, to obtain tannic acid modified layered graphene oxide;

[0131] B2. 2.5 g of zinc nitrate hexahydrate, 2 g of 2-amino benzothiazole and 2.9 g of 2-methyl imidazole were added to 85 mL of methanol, stirred until uniform, 1.7 g of sodium formate and 5.9 g of tannic acid modified layered graphene oxide were added, stirred until uniform, nitrogen was introduced, reacted at 70°C for 5 h, centrifuged at a speed of 8000 r / min, washed with methanol for 3 times, washed with deionized water for 3 times, dried in an oven at 60°C for 10 min, to obtain modified layered graphene oxide.

[0132] Comparative Example 4

[0133] A low-temperature lithium battery separator material containing nanoceramic material, the preparation method comprising the following preparation steps:

[0134] S1. mixing the modified nanoceramic material, the modified layered graphene oxide, carboxymethyl cellulose and deionized water to obtain a mixed slurry;

[0135] S2. spraying the mixed slurry onto the upper and lower surfaces of the polypropylene separator, drying and curing at 60℃ for 30min to obtain a lithium battery separator material.

[0136] In step S1, the mass ratio of the modified nanoceramic material, the modified layered graphene oxide, carboxymethyl cellulose and deionized water is 25:15:1:60;

[0137] In step S2, the spraying amount of the mixed slurry on the upper and lower surfaces of the polypropylene separator is 22g / m 2 , and the spraying pressure is 0.5MPa;

[0138] The thickness of the polypropylene separator is 15μm, and the thickness of the lithium battery separator material is 40μm.

[0139] The modified nanoceramic material is prepared by the following steps:

[0140] A1. 6g of nanoceramic material, 4g of glucose and 0.7g of citric acid are added to 120mL of ethanol, stirred uniformly, 0.6mL of 36% hydrochloric acid is added, stirred at 70℃ for 35min, filtered, washed with deionized water for 3 times, dried in a 70℃ oven for 10min, placed in a tube furnace, 6mL of 30% potassium hydroxide solution is added, nitrogen is introduced, the nitrogen flow is 30mL / min, the temperature is raised to 850℃, carbonization is carried out for 5h, the heating rate is 10℃ / min, cooled to room temperature, taken out, washed with deionized water for 3 times, dried in a 70℃ oven for 10min to obtain a nanoceramic material loaded with porous carbon;

[0141] A2. 5.5g of silicon carbide whiskers are added to 85mL of Tris-HCl buffer solution with pH 8.5, stirred uniformly, 0.7g of dopamine is added, stirred at 25℃ and 800r / min for 3.5h, filtered, washed with deionized water for 3 times, dried in a 70℃ oven for 10min to obtain polydopamine modified silicon carbide whiskers;

[0142] A3. 5g of polydopamine modified silicon carbide whiskers and 3.6g of nanoceramic material loaded with porous carbon are added to 110mL of deionized water, stirred at 900r / min for 25min, stand for 1h, filtered, washed with deionized water for 3 times, dried in a 70℃ oven for 10min to obtain a modified nanoceramic material.

[0143] The modified layered graphene oxide is prepared by the following steps:

[0144] 2.5 g of zinc nitrate hexahydrate, 2 g of 2-amino benzothiazole and 2.9 g of 2-methyl imidazole were added into 85 mL of methanol, stirred uniformly, 1.7 g of sodium formate and 5.9 g of sheet graphene oxide were added and stirred uniformly, nitrogen was introduced, reaction was carried out at 70°C for 5 h, centrifugation was carried out at a speed of 8000 r / min, washing was carried out with methanol for 3 times, washing was carried out with deionized water for 3 times, drying was carried out in an oven at 60°C for 10 min, and modified sheet graphene oxide was obtained.

[0145] Comparative Example 5

[0146] A low-temperature lithium battery diaphragm material containing a nano ceramic material, and a preparation method thereof, includes the following preparation steps:

[0147] S1. The modified nano ceramic material, tannic acid modified sheet graphene oxide, carboxymethyl cellulose and deionized water were mixed to obtain a mixed slurry;

[0148] S2. The mixed slurry was sprayed onto the upper and lower surfaces of the polypropylene diaphragm, and drying and curing were carried out at 60°C for 30 min to obtain a lithium battery diaphragm material.

[0149] In step S1, the mass ratio of the modified nano ceramic material, tannic acid modified sheet graphene oxide, carboxymethyl cellulose and deionized water is 25:15:1:60;

[0150] In step S2, the spraying amount of the mixed slurry on the upper and lower surfaces of the polypropylene diaphragm is 22 g / m 2 , and the spraying pressure is 0.5 MPa;

[0151] The thickness of the polypropylene diaphragm is 15 μm, and the thickness of the lithium battery diaphragm material is 40 μm.

[0152] The modified nano ceramic material is prepared by the following steps:

[0153] A1. 6 g of nano ceramic material, 4 g of glucose and 0.7 g of citric acid were added into 120 mL of ethanol, stirred uniformly, 0.6 mL of 36% hydrochloric acid was added, stirred and reacted at 70°C for 35 min, filtered, washed with deionized water for 3 times, dried in an oven at 70°C for 10 min, placed in a tube furnace, 6 mL of 30% potassium hydroxide solution was added, nitrogen was introduced, the nitrogen flow was 30 mL / min, the temperature was raised to 850°C, carbonization was carried out for 5 h, the temperature raising rate was 10°C / min, cooled to room temperature, taken out, washed with deionized water for 3 times, and dried in an oven at 70°C for 10 min to obtain a nano ceramic material loaded with porous carbon;

[0154] A2. 5.5 g of silicon carbide whiskers were added to 85 mL of Tris-HCl buffer with pH 8.5, stirred uniformly, 0.7 g of dopamine was added, stirred at 25℃, 800 r / min for 3.5 h, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain polydopamine modified silicon carbide whiskers;

[0155] A3. 5 g of polydopamine modified silicon carbide whiskers and 3.6 g of nano-ceramic material loaded with porous carbon were added to 110 mL of deionized water, stirred at 900 r / min for 25 min, and after standing for 1 h, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain modified nano-ceramic material.

[0156] The tannic acid modified layered graphene oxide was prepared by the following steps:

[0157] 1 g of tannic acid was added to 55 mL of ethanol, stirred until completely dissolved, 2.4 g of layered graphene oxide was added, stirred at 50℃ for 30 min, filtered, washed with deionized water for 3 times, dried in an oven at 70℃ for 10 min, to obtain tannic acid modified layered graphene oxide.

[0158] The lithium battery separator materials prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to performance detection.

[0159] The lithium battery separator material used for testing had a width of 20 mm, a length of 40 mm, and a thickness of 35 μm.

[0160] Tensile strength test: The lithium battery separator material prepared above was subjected to longitudinal and transverse tensile strength test using a Qiangtong CTM universal testing machine, 5 samples were tested in each direction, and the average value was calculated, and the test temperature was 25℃.

[0161] Heat resistance test: The thermal shrinkage rate was measured using a battery separator thermal shrinkage rate tester.

[0162] Electrochemical performance test: lithium iron phosphate: carbon black: polyvinylidene fluoride were mixed in a ratio of 8:1:1, coated on aluminum foil, dried at 110℃, cut into a circular piece with a diameter of 13 mm as a positive electrode material, the negative electrode material was pure lithium sheet, the separator was the lithium battery separator material prepared above, and the positive and negative electrode shells were CR2032 type, and the battery was assembled;

[0163] The battery was placed at 25℃ and -25℃, the voltage was 3V, the constant current charge and discharge was carried out at 1C rate, the cycle was 200 times, the voltage protection was set between 0-4.25V, and the discharge capacity of the battery at 25℃ and -25℃ was recorded.

[0164] The test results are shown in Table 1 below.

[0165] Table 1 Performance detection of lithium battery separator materials prepared in examples 1-3 and comparative examples 1-5

[0166]

[0167] As can be seen from the data in Table 1, the lithium battery separator materials prepared in examples 1-3 have high mechanical properties, high and low temperature resistance and electrochemical properties.

[0168] In comparative example 1, the porous carbon loaded nanoceramic material is replaced by the modified nanoceramic material prepared from nanoceramic material, which is coated on the lithium battery separator material, and the mechanical properties and high and low temperature resistance decrease, proving that the porous carbon synthesized on the surface of the nanoceramic material has high pore structure and pore capacity, accelerates the transmission performance of lithium ions, enhances the migration rate of lithium ions, and increases the surface roughness of the nanoceramic material, increases the contact area of the nanoceramic material and the electrolyte, and improves the number of lithium ion migration, in addition, it can hinder the collapse of the hole shrinkage of the separator at low temperature, so that the lithium ion transmission performance of the separator at low temperature is still maintained.

[0169] In comparative example 2, the polydopamine modified silicon carbide whisker is replaced by the modified nanoceramic material prepared from silicon carbide whisker, which is coated on the lithium battery separator material, and the mechanical properties and high and low temperature resistance decrease, proving that the polydopamine modified silicon carbide whisker improves the surface activity of the silicon carbide whisker, which is beneficial to the deposition of the porous carbon loaded nanoceramic material on the surface of the silicon carbide whisker, avoids the agglomeration of the porous carbon loaded nanoceramic material, and affects the mechanical properties and high and low temperature resistance of the separator material.

[0170] In comparative example 3, the silicon carbide whisker is replaced by the modified nanoceramic material prepared from silicon carbide particles, which is coated on the lithium battery separator material, and the mechanical properties and high and low temperature resistance decrease, proving that the silicon carbide whisker has excellent aspect ratio, which is randomly distributed on the surface of the separator to form a network structure that can absorb and weaken external force, improve the mechanical properties of the separator, and the silicon carbide whisker has good low temperature resistance, so that the separator has good lithium ion transmission performance at low temperature, in addition, the silicon carbide whisker surface contains porous carbon, which forms a lithium ion transmission channel on the surface of the separator, shortens the lithium ion transmission path, and improves the charge and discharge efficiency of the lithium ion battery.

[0171] In comparative example 4, the tannic acid modified layered graphene oxide is replaced by the modified layered graphene oxide prepared from layered graphene oxide, which is coated on the lithium battery separator material, and the mechanical properties and high and low temperature resistance decrease, proving that the surface of the layered graphene oxide is modified by tannic acid, which is beneficial to the synthesis of zinc based metal organic framework on the surface of the layered graphene, which is coated on the surface of the separator to improve the lithium ion transmission performance, temperature resistance and mechanical properties of the separator.

[0172] The comparative example 5 replaces the modified sheet layer graphene oxide with tannin acid modified sheet layer graphene oxide coated on the lithium battery separator material, and the mechanical properties and electrochemical properties decrease, which proves that the synthesized zinc-based metal organic framework has high adsorption performance on lithium ions, improves the enrichment of lithium ions on the surface of the separator, shortens the distance of lithium ions from the electrolyte to the electrode, and improves the transmission performance of lithium ions.

[0173] In the description of the specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0174] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as it does not deviate from the invention or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A low temperature lithium battery separator material containing nanoceramic material, characterized in that, The preparation method comprises the following preparation steps: S1. The modified nanoceramic material, the modified sheet layer graphene oxide, the binder and the deionized water are mixed to obtain a mixed slurry; S2. The mixed slurry is sprayed onto the upper and lower surfaces of the polyolefin separator, and is dried and cured to obtain a lithium battery separator material; The modified nanoceramic material is obtained by synthesizing porous carbon on the surface of the nanoceramic material, and then depositing the porous carbon on the surface of the polydopamine modified silicon carbide whisker; The modified sheet layer graphene oxide is obtained by modifying the sheet layer graphene oxide with tannic acid, and then mixing and reacting the modified sheet layer graphene oxide with a zinc source and dimethyl imidazole; The modified nanoceramic material is prepared by the following steps: A1. The nanoceramic material, glucose and citric acid are added into ethanol, stirred uniformly, hydrochloric acid is added, stirred and reacted, filtered, washed, dried, mixed with potassium hydroxide solution, inert gas is introduced, carbonized at 750-850 DEG C for 3-5 hours, cooled to room temperature, taken out, washed, dried to obtain the nanoceramic material loaded with porous carbon; A2. The silicon carbide whisker is added into Tris-HCl buffer solution, stirred uniformly, dopamine is added, stirred and reacted, filtered, washed, dried to obtain the polydopamine modified silicon carbide whisker; A3. The polydopamine modified silicon carbide whisker and the nanoceramic material loaded with porous carbon are added into deionized water, stirred, placed, filtered, washed, dried to obtain the modified nanoceramic material; The modified sheet layer graphene oxide is prepared by the following steps: B1. The tannic acid is added into ethanol, stirred until completely dissolved, the sheet layer graphene oxide is added, stirred uniformly, filtered, washed, dried to obtain the sheet layer graphene oxide modified with tannic acid; B2. The zinc nitrate hexahydrate, 2-amino benzothiazole and 2-methyl imidazole are added into methanol, stirred, sodium formate and the sheet layer graphene oxide modified with tannic acid are added, stirred, inert gas is introduced, reacted at 60-70 DEG C for 3-5 hours, centrifuged, washed, dried to obtain the modified sheet layer graphene oxide.

2. The low temperature lithium battery separator material containing nanoceramic material according to claim 1, characterized in that, In step A1, the amount ratio of the nanoceramic material, glucose, citric acid, ethanol, hydrochloric acid and potassium hydroxide solution is (5-6) g:(3-4) g:(0.5-0.7) g:(80-120) mL:(0.4-0.6) mL:(4-6) mL.

3. The low temperature lithium battery separator material containing nanoceramic material as claimed in claim 1, wherein, In step A2, the amount ratio of the silicon carbide whisker, Tris-HCl buffer solution and dopamine is (5.1-5.5) g:(75-85) mL:(0.5-0.7) g.

4. The low temperature lithium battery separator material containing nanoceramic material of claim 1, wherein, In step A3, the amount ratio of the polydopamine modified silicon carbide whisker, the nanoceramic material loaded with porous carbon and deionized water is (4-5) g:(3-3.6) g:(90-110) mL.

5. The low temperature lithium battery separator material containing nanoceramic material as claimed in claim 1, wherein, In step B1, the amount ratio of the tannic acid, ethanol and sheet layer graphene oxide is (0.6-1) g:(45-55) mL:(2-2.4) g.

6. The low temperature lithium battery separator material containing nanoceramic material of claim 1, wherein, In step B2, the amount ratio of the zinc nitrate hexahydrate, 2-amino benzothiazole, 2-methyl imidazole, methanol, sodium formate and tannic acid modified sheet layer graphene is (1.5-2.5)g:(1.6-2)g:(2.5-2.9)g:(75-85)mL:(1.3-1.7)g:(5.5-5.9)g.

7. The low temperature lithium battery separator material containing nanoceramic material as claimed in claim 1, wherein, In step S1, the mass ratio of the modified nanoceramic material, modified sheet layer graphene, binder and deionized water is (20-25):(10-15):(0.5-1):(40-60).

8. The low temperature lithium battery separator material containing nanoceramic material as claimed in claim 1, wherein, In step S2, the mixed slurry is sprayed onto the upper and lower surfaces of the polyolefin separator at a spraying amount of 18-22 g / m 2 , and a spraying pressure of 0.3-0.5 MPa.

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