A carbon-coated aluminum foil with good thermal conductivity

Abstract

The invention relates to a carbon-coated aluminum foil with good thermal conductivity, belonging to the technical field of lithium battery materials. The pretreated aluminum foil is used as a substrate and a conductive and thermally conductive carbon slurry is coated on the surface of the pretreated aluminum foil. The specific preparation steps are as follows: the pretreated aluminum foil is obtained by washing and roughening; 5-15 parts of carbon material, 5-8 parts of reinforcing particles, 3-5 parts of ultraviolet curing resin, 3-5 parts of modified cellulose nanocrystals, 0.5-1 parts of photoinitiator, 65-90 parts of deionized water and 0.3-1 parts of auxiliary agent are prepared by weight; the raw materials are added into a mixer and stirred evenly to obtain the conductive and thermally conductive carbon slurry; the conductive and thermally conductive carbon slurry is coated on the aluminum foil and kept in a hot air ultraviolet light irradiation oven for 100-200 seconds; the reinforcing particles and the modified cellulose nanocrystals are introduced into the slurry, so that the amount of binder can be reduced and the thermal conductivity and electrical conductivity of the aluminum foil can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium battery materials, and in particular relates to a carbon-coated aluminum foil with good thermal conductivity. Background Art

[0002] Lithium-ion batteries generally use aluminum foil or carbon-coated aluminum foil as a carrier of positive electrode materials. By coating the surface of aluminum foil with a conductive carbon layer, battery polarization can be suppressed, thermal effects can be reduced, and the rate performance of the battery can be improved. At the same time, the adhesion between the active material and the aluminum foil can be improved, and the amount of binder can be reduced. The lithium battery using the carbon-coated aluminum foil has good conductivity, rate performance and heat dissipation performance.

[0003] However, in the preparation process of existing carbon-coated aluminum foil for lithium batteries, effective treatment of the surface oxide layer and oil pollution of lithium batteries is ignored, so carbon coating is directly performed, resulting in poor conductivity, inability to reduce interface resistance, reduced low-temperature discharge capability of the battery, and shortened cycle life. At the same time, the carbon coating method is not very reasonable, resulting in unsatisfactory results. The formation of many carbon coating layers needs to be formed under high temperature conditions. For example, the epoxy-amino adhesive requires a temperature of 170-180°C and a cross-linking time of more than 1 minute to fully cross-link. Its cross-linking efficiency is low, which is not conducive to the growth of the assembly line. At present, the aluminum foil in lithium batteries is between 12-20μm. Under high-temperature baking, the aluminum foil will be severely deformed, changing the tension distribution, resulting in difficulties in subsequent processing. In addition, the existing aluminum foil has poor thermal conductivity, resulting in poor heat dissipation of the manufactured lithium battery, affecting the service life of the lithium battery. Summary of the invention

[0004] In order to solve the technical problem mentioned in the background technology, the present invention provides a carbon-coated aluminum foil with good thermal conductivity.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A carbon-coated aluminum foil with good thermal conductivity is prepared by using a pretreated aluminum foil as a substrate and coating the surface with a conductive and thermally conductive carbon slurry. The specific preparation steps are as follows:

[0007] The first step is to obtain a pre-treated aluminum foil by cleaning and roughening;

[0008] The second step is to coat the conductive and thermally conductive carbon slurry on the aluminum foil with a coating thickness of 1-3 μm, and keep it in a hot air oven at 60-110°C and UV light with a wavelength of 300-400nm for 100-200s to obtain a carbon-coated aluminum foil with good thermal conductivity.

[0009] Further, the conductive and thermal conductive carbon slurry is prepared by the following steps:

[0010] Prepare 5-15 parts of carbon material, 5-8 parts of reinforcing particles, 3-5 parts of UV-curable resin, 3-5 parts of modified cellulose nanocrystals, 0.5-1 part of photoinitiator, 65-90 parts of deionized water, and 0.3-1 part of auxiliary agent by weight; add the above raw materials into a mixer and stir evenly to obtain a conductive and thermally conductive carbon slurry.

[0011] Further, the reinforced particles are prepared by the following steps:

[0012] The carboxylated single-walled carbon nanotubes are added to a sodium dodecylbenzene sulfonate solution, ultrasonically dispersed for 2 hours under ice bath conditions, and then transferred to a 0.1 mol / L silver nitrate solution. After magnetic stirring for 6-8 hours, a 0.1 mol / L ascorbic acid solution is added dropwise at a rate of 10 mL / min. After the addition is completed, the mixture is stirred for reaction at room temperature for 0.5-1 hour, allowed to stand for 6-8 hours, and then centrifuged. The precipitate is washed with ethanol and then dried to obtain enhanced particles. The carboxylated single-walled carbon nanotubes, sodium dodecylbenzene sulfonate solution, silver nitrate solution, and ascorbic acid solution 3g: 200-300mL: 100mL: 200-300mL. The sodium dodecylbenzene sulfonate solution is a sodium dodecylbenzene sulfonate aqueous solution with a mass fraction of 2-5%. The carboxylated single-walled carbon nanotubes with high thermal and electrical conductivity are used as raw materials, and the enhanced particles are obtained through a reduction reaction.

[0013] Further, the modified cellulose nanocrystals are prepared by the following steps:

[0014] The carboxylated cellulose nanocrystals are placed in DMF, ultrasonicated for 30 minutes, and then active polythiophene is added. After stirring for 5-10 minutes, p-toluenesulfonic acid is added, and the temperature is raised to 80-85°C and stirred for reaction for 24 hours. After the reaction is completed, centrifugal washing and freeze-drying are performed to obtain modified cellulose nanocrystals. The mass ratio of carboxylated cellulose nanocrystals, DMF, active polythiophene and p-toluenesulfonic acid is 1:20-30:1:0.02-0.04, so that the active polythiophene is connected to the molecular chain of the carboxylated cellulose nanocrystal through chemical bonds to obtain modified cellulose nanocrystals.

[0015] Further, the active polythiophene is prepared by the following steps:

[0016] Step S1, add 3-thiopheneacetic acid, 2-chloroethoxyethanol and toluene into a three-necked flask, add p-toluenesulfonic acid, and react under nitrogen protection at 100-105° C. for 6-8 hours with stirring. After the reaction is completed, cool to room temperature, add deionized water for washing, collect the organic phase, dry it with anhydrous magnesium sulfate, filter, and rotary evaporate the filtrate to obtain intermediate 1;

[0017] The amount ratio of 3-thiopheneacetic acid, 2-chloroethoxyethanol and toluene is 5mmol:6-8mmol:40-50mL, the amount of p-toluenesulfonic acid is 1-2% of the total mass of 3-thiopheneacetic acid and 2-chloroethoxyethanol, and the intermediate 1 is obtained by esterification reaction. The specific reaction process is as follows:

[0018]

[0019] Step S2: Add anhydrous FeCl 3 and dry chloroform, ultrasonically treat for 20 min under nitrogen protection, add the chloroform solution of intermediate 1 dropwise, stir at 0°C for 24 h after the addition is complete, then warm to room temperature and stir to react for 8-10 h. After the reaction is complete, remove the organic solvent by rotary evaporation, add methanol and hydrazine hydrate, stir at 40°C for 4 h, filter, wash with water until the filtrate is colorless, extract with methanol Soxhlet for 24 h, and dry at 60°C in vacuum to constant weight to obtain intermediate 2;

[0020] Among them, anhydrous FeCl 3 , dry chloroform, chloroform solution of intermediate 1, methanol and hydrazine hydrate in a ratio of 4mmol:30-40mL:20mL:50mL:1.5mmol, the chloroform solution of intermediate 1 is composed of intermediate 1 and chloroform in a ratio of 1mmol:20mL, in FeCl 3 The polymer intermediate 2 is synthesized under catalysis, and the specific reaction process is as follows:

[0021]

[0022] Step S3, DMF, diethanolamine, intermediate 2, potassium carbonate and potassium iodide were added to a round-bottom flask, heated to 70°C under nitrogen protection, reacted for 60-72 hours, and then the reaction was stopped. Methanol was added for recrystallization, filtered, the filter cake was washed with water until the solution was colorless, and vacuum dried to obtain active polythiophene;

[0023] The dosage ratio of DMF, diethanolamine, intermediate 2, potassium carbonate and potassium iodide is 30 mL: 5 mmol: 0.12-0.15 g: 1.5 mmol: 1.5 mmol. Active polythiophene is obtained by substitution reaction. The specific reaction process is as follows:

[0024]

[0025] Further, the carboxylated cellulose nanocrystals are prepared by the following steps:

[0026] The cellulose nanocrystals and maleic anhydride are dispersed in DMF, and then stirred and reacted at 120°C for 20-22 hours under a nitrogen atmosphere. After the reaction is completed, the mixture is allowed to stand for 6-8 hours and filtered. The filter cake is washed with anhydrous ethanol and deionized water, and freeze-dried to obtain carboxylated cellulose nanocrystals. The mass ratio of cellulose nanocrystals, maleic anhydride and DMF is 1-3:10:100. The cellulose nanocrystals are modified with maleic anhydride through an esterification reaction at high temperature to obtain carboxylated cellulose nanocrystals.

[0027] Furthermore, the roughening treatment adopts alkaline washing or acid washing, specifically: the aluminum foil is placed in a 0.1-0.5 mol / L sodium hydroxide or phosphoric acid solution for washing for 10-50 seconds, and the washing temperature is 40-60°C.

[0028] Furthermore, the carbon material includes one or more of graphene, graphite, conductive carbon black, vapor-grown carbon fiber and Ketjen black mixed in any proportion.

[0029] Furthermore, the UV-curable resin is one of epoxy-modified acrylic resin and polyurethane-modified acrylic resin.

[0030] Furthermore, the photoinitiator is benzophenone or benzoin isopropyl alcohol.

[0031] Furthermore, the auxiliary agent is polyvinyl pyrrolidone or 2-hydroxyphosphoryl acetic acid.

[0032] Beneficial effects of the present invention:

[0033] 1. In order to overcome the problem that the carbon layer of traditional aluminum foil is formed at high temperature and affects the performance of aluminum foil, the present invention adopts ultraviolet light curing resin as the main curing raw material, and forms a carbon layer on the surface of aluminum foil through light curing and heat curing, which is not only simple in process, but also energy-saving and efficient.

[0034] 2. In order to improve the thermal and electrical conductivity of aluminum foil, the present invention introduces reinforcing particles into the conductive and thermally conductive carbon slurry. The reinforcing particles are single-walled carbon nanotubes with nanosilver on the surface. The reinforcing particles are obtained by utilizing the interaction between carboxyl groups and silver ions and using carboxylated single-walled carbon nanotubes as raw materials. The reinforcing particles have excellent electrical and thermal conductivity. When added to the slurry, they can form a three-dimensional thermal conductive network with the carbon material. The presence of nanosilver serves as a conductive and thermally conductive reinforcement point, filling the gap between the carbon material and the carbon nanotubes, making the three-dimensional network connection more tightly connected, thereby improving the electrical and thermal conductivity of the carbon layer.

[0035] 3. In order to improve the thermal and electrical conductivity of aluminum foil, the present invention introduces modified cellulose nanocrystals into the conductive and thermally conductive carbon slurry. The cellulose nanocrystals are composed of active polythiophene connected by chemical bonds in the molecular chains. When they are added to the slurry, on the one hand, they play a bonding role, reduce the amount of adhesive resin, and make up for the effect of the use of adhesives on reducing the electrical and thermal conductivity of the carbon layer. On the other hand, the high thermal and electrical conductivity of polythiophene is exerted to improve the electrical conductivity and thermal resistance of the carbon layer. The hydroxyl groups on the molecular chain can participate in the curing reaction and increase the cross-linking density of the carbon layer. The presence of multiple hydrophilic groups in the molecule has good hydrophilicity and improves the dispersibility of the carbon material in the slurry through interactions such as hydrogen bonds. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] A modified cellulose nanocrystal is prepared by the following steps:

[0039] 1 g of cellulose nanocrystals and 10 g of maleic anhydride were dispersed in 100 g of DMF, and then stirred at 120° C. for 20 h under a nitrogen atmosphere. After the reaction was completed, the mixture was allowed to stand for 6 h and filtered. The filter cake was washed with anhydrous ethanol and deionized water, and freeze-dried to obtain carboxylated cellulose nanocrystals.

[0040] 1 g of carboxylated cellulose nanocrystals was placed in 20 g of DMF. After ultrasonic treatment for 30 min, 1 g of active polythiophene was added. After stirring for 5 min, 0.02 g of p-toluenesulfonic acid was added. The temperature was raised to 80 °C and stirred for 24 h. After the reaction was completed, the cellulose nanocrystals were centrifuged, washed, and freeze-dried to obtain modified cellulose nanocrystals.

[0041] Reactive polythiophene is prepared by the following steps:

[0042] Step S1, add 5mmol 3-thiopheneacetic acid, 6mmol 2-chloroethoxyethanol and 40mL toluene into a three-necked flask, add p-toluenesulfonic acid, and react for 6h at 100°C under nitrogen protection. After the reaction is completed, cool to room temperature, add deionized water for washing, collect the organic phase, dry it with anhydrous magnesium sulfate, filter, and rotary evaporate the filtrate to obtain intermediate 1, wherein the amount of p-toluenesulfonic acid is 1% of the total mass of 3-thiopheneacetic acid and 2-chloroethoxyethanol;

[0043] Step S2: Add 4 mmol of anhydrous FeCl into the round-bottom flask.3 and 30mL dry chloroform, ultrasonically treated for 20min under nitrogen protection, and then the chloroform solution of intermediate 1 was added dropwise. After the addition was completed, it was stirred at 0°C for 24h, then heated to room temperature and stirred for 8h. After the reaction was completed, the organic solvent was removed by rotary evaporation, 50mL methanol and 1.5mmol hydrazine hydrate were added, and the mixture was stirred at 40°C for 4h and then filtered. The mixture was washed with water until the filtrate was colorless, and then extracted with methanol Soxhlet for 24h, and dried under vacuum at 60°C to constant weight to obtain intermediate 2. The chloroform solution of intermediate 1 was composed of intermediate 1 and chloroform in a dosage ratio of 1mmol:20mL;

[0044] Step S3, add 30 mL DMF, 5 mmol diethanolamine, 0.12 g intermediate 2, 1.5 mmol potassium carbonate and 1.5 mmol potassium iodide to a round-bottom flask, heat to 70 ° C under nitrogen protection, react for 60-72 hours and then stop the reaction, add methanol for recrystallization, filter, wash the filter cake with water until the solution is colorless, and vacuum dry to obtain active polythiophene.

[0045] Example 2

[0046] A modified cellulose nanocrystal is prepared by the following steps:

[0047] 3 g of cellulose nanocrystals and 10 g of maleic anhydride were dispersed in 100 g of DMF, and then stirred at 120° C. for 22 h under a nitrogen atmosphere. After the reaction was completed, the mixture was allowed to stand for 8 h and filtered. The filter cake was washed with anhydrous ethanol and deionized water, and freeze-dried to obtain carboxylated cellulose nanocrystals.

[0048] 1 g of carboxylated cellulose nanocrystals was placed in 30 g of DMF. After ultrasonic treatment for 30 min, 1 g of active polythiophene was added. After stirring for 10 min, 0.04 g of p-toluenesulfonic acid was added. The temperature was raised to 85 °C and stirred for 24 h. After the reaction was completed, the cellulose nanocrystals were centrifuged, washed, and freeze-dried to obtain modified cellulose nanocrystals.

[0049] Reactive polythiophene is prepared by the following steps:

[0050] Step S1, add 5mmol 3-thiopheneacetic acid, 8mmol 2-chloroethoxyethanol and 50mL toluene into a three-necked flask, add p-toluenesulfonic acid, and react under nitrogen protection at 105°C for 8h. After the reaction is completed, cool to room temperature, add deionized water for washing, collect the organic phase, dry it with anhydrous magnesium sulfate, filter, and rotary evaporate the filtrate to obtain intermediate 1, wherein the amount of p-toluenesulfonic acid is 2% of the total mass of 3-thiopheneacetic acid and 2-chloroethoxyethanol;

[0051] Step S2: Add 4 mmol of anhydrous FeCl into the round-bottom flask. 3and 40mL dry chloroform, ultrasonically treated for 20min under nitrogen protection, and then the chloroform solution of intermediate 1 was added dropwise. After the addition was completed, the mixture was stirred at 0°C for 24h, then heated to room temperature and stirred for 10h. After the reaction was completed, the organic solvent was removed by rotary evaporation, 50mL methanol and 1.5mmol hydrazine hydrate were added, and the mixture was stirred at 40°C for 4h and then filtered. The mixture was washed with water until the filtrate was colorless, and then extracted with methanol Soxhlet for 24h, and dried under vacuum at 60°C to constant weight to obtain intermediate 2. The chloroform solution of intermediate 1 consisted of intermediate 1 and chloroform in a dosage ratio of 1mmol:20mL.

[0052] Step S3, add 30 mL DMF, 5 mmol diethanolamine, 0.15 g intermediate 2, 1.5 mmol potassium carbonate and 1.5 mmol potassium iodide into a round-bottom flask, heat to 70 ° C under nitrogen protection, react for 72 hours and stop the reaction, add methanol for recrystallization, filter, wash the filter cake with water until the solution is colorless, and vacuum dry to obtain active polythiophene.

[0053] Comparative Example 1

[0054] Add 4 mmol of anhydrous FeCl into the round-bottom flask 3 and 40mL dry chloroform, ultrasonically treated for 20min under nitrogen protection, and then the chloroform solution of 3-methoxythiophene was added dropwise. After the addition was completed, the mixture was stirred at 0°C for 24h, then heated to room temperature and stirred for 10h. After the reaction was completed, the organic solvent was removed by rotary evaporation, 50mL methanol and 1.5mmol hydrazine hydrate were added, and the mixture was stirred at 40°C for 4h and then filtered. The mixture was washed with water until the filtrate was colorless and extracted with methanol Soxhlet for 24h. The mixture was vacuum dried at 60°C to constant weight to obtain polythiophene. The chloroform solution of 3-methoxythiophene was composed of 3-methoxythiophene and chloroform in a dosage ratio of 1mmol:20mL.

[0055] The polythiophene and cellulose nanocrystals are mixed in a mass ratio of 1:1 to obtain modified cellulose nanocrystals.

[0056] Comparative Example 2

[0057] This comparative example is cellulose nanocrystals.

[0058] Example 3

[0059] A carbon-coated aluminum foil with good thermal conductivity, the preparation steps are as follows:

[0060] The pretreated aluminum foil is obtained by cleaning and roughening treatment; the conductive and thermal conductive carbon slurry is coated on the aluminum foil with a coating thickness of 1 μm, and is kept in a hot air oven at 60° C. and an ultraviolet light oven with a wavelength of 400 nm for 100 seconds.

[0061] Electrically and thermally conductive carbon paste is made by the following steps:

[0062] Prepare, by weight, 5 parts of carbon material, 5 parts of reinforcing particles, 3 parts of UV-curable resin, 3 parts of modified cellulose nanocrystals of Example 1, 0.5 parts of benzophenone, 65 parts of deionized water, and 0.3 parts of polyvinyl pyrrolidone; add the above raw materials into a mixer and stir evenly to obtain a conductive and thermally conductive carbon slurry.

[0063] The reinforced particles are made by the following steps:

[0064] 3 g of carboxylated single-walled carbon nanotubes were added to 200 mL of sodium dodecylbenzenesulfonate solution, and after ultrasonic dispersion for 2 h in an ice bath, the solution was transferred to 100 mL of 0.1 mol / L silver nitrate solution, and magnetically stirred for 8 h. Then, 200 mL of 0.1 mol / L ascorbic acid solution was added dropwise at a rate of 10 mL / min. After the addition was completed, the solution was stirred for reaction at room temperature for 0.5 h. After standing for 6 h, the solution was centrifuged, and the precipitate was washed with ethanol and dried to obtain enhanced particles. The sodium dodecylbenzenesulfonate solution was a 2% by mass sodium dodecylbenzenesulfonate aqueous solution.

[0065] The roughening treatment is as follows: the aluminum foil is placed in 0.1 mol / L sodium hydroxide and cleaned for 10 seconds at a cleaning temperature of 60°C.

[0066] The carbon material is composed of graphene and conductive carbon black in a mass ratio of 1:1, and the ultraviolet light curing resin is polyurethane modified acrylic resin.

[0067] Example 4

[0068] A carbon-coated aluminum foil with good thermal conductivity, the preparation steps are as follows:

[0069] The pretreated aluminum foil is obtained by cleaning and roughening treatment; the conductive and thermal conductive carbon slurry is coated on the aluminum foil with a coating thickness of 2 μm, and is kept in a hot air oven at 80° C. and an ultraviolet light oven with a wavelength of 350 nm for 150 seconds.

[0070] Electrically and thermally conductive carbon paste is made by the following steps:

[0071] Prepare, by weight, 10 parts of carbon material, 7 parts of reinforcing particles, 4 parts of UV-curable resin, 4 parts of modified cellulose nanocrystals of Example 1, 0.8 parts of photoinitiator, 80 parts of deionized water, and 0.5 parts of auxiliary agent; add the above raw materials into a mixer, stir evenly, and obtain a conductive and thermally conductive carbon slurry.

[0072] The reinforced particles are made by the following steps:

[0073] 3 g of carboxylated single-walled carbon nanotubes were added to 250 mL of sodium dodecylbenzene sulfonate solution, and after ultrasonic dispersion for 2 h in an ice bath, the solution was transferred to 100 mL of 0.1 mol / L silver nitrate solution, and magnetically stirred for 7 h. Then, 250 mL of 0.1 mol / L ascorbic acid solution was added dropwise at a rate of 10 mL / min. After the addition was completed, the solution was stirred for reaction at room temperature for 0.8 h. After standing for 7 h, the solution was centrifuged, and the precipitate was washed with ethanol and dried to obtain enhanced particles. The sodium dodecylbenzene sulfonate solution was a 5% by mass sodium dodecylbenzene sulfonate aqueous solution.

[0074] The roughening treatment adopts the acid pickling method, specifically: the aluminum foil is placed in a 0.5 mol / L phosphoric acid solution for cleaning for 50 seconds, and the cleaning temperature is 40°C.

[0075] The carbon material is composed of graphene and conductive carbon black in a mass ratio of 1:1, the UV-curable resin is polyurethane-modified acrylic resin, the photoinitiator is benzophenone, and the auxiliary agent is polyvinyl pyrrolidone.

[0076] Example 5

[0077] A carbon-coated aluminum foil with good thermal conductivity, the preparation steps are as follows:

[0078] The pretreated aluminum foil is obtained by cleaning and roughening treatment; the conductive and thermal conductive carbon slurry is coated on the aluminum foil with a coating thickness of 3 μm, and is kept in a hot air oven at 110° C. and an ultraviolet light oven with a wavelength of 400 nm for 200 seconds.

[0079] Electrically and thermally conductive carbon paste is made by the following steps:

[0080] Prepare, by weight, 15 parts of carbon material, 8 parts of reinforcing particles, 5 parts of UV-curable resin, 5 parts of modified cellulose nanocrystals of Example 2, 1 part of photoinitiator, 90 parts of deionized water, and 1 part of auxiliary agent; add the above raw materials into a mixer, stir evenly, and obtain a conductive and thermally conductive carbon slurry.

[0081] The reinforced particles are made by the following steps:

[0082] 3 g of carboxylated single-walled carbon nanotubes were added to 300 mL of sodium dodecylbenzene sulfonate solution, and after ultrasonic dispersion for 2 h in an ice bath, the solution was transferred to 100 mL of 0.1 mol / L silver nitrate solution, and magnetically stirred for 8 h. Then, 300 mL of 0.1 mol / L ascorbic acid solution was added dropwise at a rate of 10 mL / min. After the addition was completed, the solution was stirred for reaction at room temperature for 1 h. After standing for 8 h, the solution was centrifuged, and the precipitate was washed with ethanol and dried to obtain enhanced particles. The sodium dodecylbenzene sulfonate solution was a 5% by mass sodium dodecylbenzene sulfonate aqueous solution.

[0083] The roughening treatment is the same as in Example 4.

[0084] The carbon material is composed of graphene and conductive carbon black in a mass ratio of 1:1, the UV-curable resin is polyurethane-modified acrylic resin, the photoinitiator is benzophenone, and the auxiliary agent is polyvinyl pyrrolidone.

[0085] Comparative Example 3

[0086] The modified cellulose nanocrystals in Example 3 were replaced by the material in Comparative Example 1, and the remaining raw materials and preparation process were the same as in Example 3.

[0087] Comparative Example 4

[0088] The modified cellulose nanocrystals in Example 4 were replaced by the material in Comparative Example 2, and the remaining raw materials and preparation process were the same as in Example 4.

[0089] Comparative Example 5

[0090] The reinforcing particles in Example 5 were removed, and the remaining raw materials and preparation process were the same as in Example 5.

[0091] The carbon-coated aluminum foils prepared in Examples 3-5 and Comparative Examples 3-5 were tested. Lithium iron phosphate slurry was coated on the samples prepared in Examples and Comparative Examples to prepare aluminum foils with a surface density of 300 g / m 2 , compacted density is 2.3g / cm 3 The electrode was used to test the impedance of the electrode. Then a 50Ah battery was made with the electrode. The surface temperature of the battery was tested. The results are shown in Table 1:

[0092] Table 1

[0093]

[0094]

[0095] It can be seen from Table 1 that, compared with Comparative Examples 3-5, the aluminum foil prepared in Example 3-5 has better thermal conductivity and electrical conductivity, and is more suitable for the preparation of lithium batteries.

[0096] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation 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.

[0097] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A carbon-coated aluminum foil with good thermal conductivity, which is prepared by using pretreated aluminum foil as the substrate and coating the surface with conductive and thermal conductive carbon slurry. It is characterized in that The specific preparation steps are as follows: The first step is to obtain a pre-treated aluminum foil by cleaning and roughening; Step 2: Prepare 5-15 parts of carbon material, 5-8 parts of reinforcing particles, 3-5 parts of UV-curable resin, 3-5 parts of modified cellulose nanocrystals, 0.5-1 parts of photoinitiator, 65-90 parts of deionized water, and 0.3-1 parts of additives by weight; add the above raw materials into a mixer and stir evenly to obtain a conductive and thermally conductive carbon slurry; The reinforced particles are made by the following steps: The carboxylated single-walled carbon nanotubes were added to a sodium dodecylbenzene sulfonate solution, and after ultrasonic dispersion for 2 hours in an ice bath, the solution was transferred to a 0.1 mol / L silver nitrate solution, and after magnetic stirring for 6-8 hours, a 0.1 mol / L ascorbic acid solution was added dropwise at a rate of 10 mL / min. After the addition was completed, the solution was stirred and reacted at room temperature for 0.5-1 hour to obtain enhanced particles; The third step is to coat the conductive and thermally conductive carbon slurry on the aluminum foil and keep it in an oven with hot air at 60-110°C and ultraviolet light with a wavelength of 300-400nm for 100-200s. Modified cellulose nanocrystals are prepared by the following steps: The carboxylated cellulose nanocrystals are placed in DMF, active polythiophene is added after ultrasonication, p-toluenesulfonic acid is added after stirring, the temperature is raised to 80-85°C, and the reaction is stirred for 24 hours. After the reaction is completed, the cellulose nanocrystals are washed by centrifugation and freeze-dried to obtain modified cellulose nanocrystals; Reactive polythiophene is prepared by the following steps: Step S1, add 3-thiopheneacetic acid, 2-chloroethoxyethanol and toluene into a three-necked flask, add p-toluenesulfonic acid, and stir the mixture at 100-105° C. for 6-8 hours under nitrogen protection to obtain intermediate 1; Step S2: Add anhydrous FeCl 3 and dry chloroform, ultrasonically treated for 20 min under nitrogen protection, and dropwise added with a chloroform solution of intermediate 1. After the dropwise addition, the mixture was stirred at 0°C for 24 h, then heated to room temperature and stirred for reaction for 8-10 h to obtain intermediate 2. Step S3, DMF, diethanolamine, intermediate 2, potassium carbonate and potassium iodide were added to a round-bottom flask, heated to 70° C. under nitrogen protection, and reacted for 60-72 hours to obtain active polythiophene.

2. A carbon-coated aluminum foil with good thermal conductivity according to claim 1, It is characterized in that The sodium dodecylbenzene sulfonate solution is a sodium dodecylbenzene sulfonate aqueous solution with a mass fraction of 2-5%.

3. A carbon-coated aluminum foil with good thermal conductivity according to claim 1, It is characterized in that In step S1, the amount of p-toluenesulfonic acid used is 1-2% of the total mass of 3-thiopheneacetic acid and 2-chloroethoxyethanol.

4. A carbon-coated aluminum foil with good thermal conductivity according to claim 1, It is characterized in that The chloroform solution of intermediate 1 in step S2 is composed of intermediate 1 and chloroform in a dosage ratio of 1 mmol:20 mL.

5. A carbon-coated aluminum foil with good thermal conductivity according to claim 1, It is characterized in that In step S3, the usage ratio of DMF, diethanolamine, intermediate 2, potassium carbonate and potassium iodide is 30 mL: 5 mmol: 0.12-0.15 g: 1.5 mmol: 1.5 mmol.

6. A carbon-coated aluminum foil with good thermal conductivity according to claim 1, It is characterized in that Carboxylated cellulose nanocrystals are prepared by the following steps: The cellulose nanocrystals and maleic anhydride were dispersed in DMF, and then stirred and reacted at 120° C. for 20-22 h under a nitrogen atmosphere to obtain carboxylated cellulose nanocrystals.

7. A carbon-coated aluminum foil having good thermal conductivity according to claim 6, It is characterized in that The mass ratio of cellulose nanocrystals, maleic anhydride and DMF is 1-3:10:

100.

8. A carbon-coated aluminum foil having good thermal conductivity according to claim 1, It is characterized in that The roughening treatment is carried out by alkali washing or acid washing.

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