Highly conductive nanocarbon coated current collector and method for manufacturing the same.

Abstract

This invention provides a highly conductive adhesive to improve the conductive performance of current collectors. To enhance the conductive performance of the conductive adhesive, the amount of conductive carbon material added is increased. At the same time, to avoid performance degradation due to an excessive amount of conductive carbon material, a branched modified polyurethane acrylate resin is used. Its substantially spherical spatial structure is utilized to reduce the overall viscosity of the adhesive, improve its flow performance, and enhance the compatibility and dispersibility of the conductive carbon material in the system. Furthermore, since the branched modified polyurethane acrylate resin contains a large number of acrylic groups, the complexity of the crosslinking network is further increased, effectively improving the viscosity of the adhesive and thus improving conductivity while avoiding a decrease in adhesive performance.

Description

Technical Field

[0001] This application relates to the technical field of lithium-ion batteries, and specifically, to a highly conductive nanocarbon-coated current collector and a method for manufacturing the same.

Background Art

[0002] Currently, in the manufacturing process of non-aqueous secondary batteries, in order to improve the rate performance of the battery and the adhesion performance of the active material to the electrode sheet, usually, a conductive material is coated on the surface of the current collector in one layer. The manufacturing process of this layer usually involves adding a conductive agent and an adhesive to water, stirring and dispersing them, and then coating them on the surface of the current collector. However, since the conventional acrylic adhesive belonging to an insulating material is used as the adhesive, as the addition amount of the adhesive increases, the conductivity of the conductive layer becomes weaker. When the conductive material is added excessively, the compatibility becomes poor, and problems such as aggregation and decrease in adhesion force occur, affecting the normal use of the current collector.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The following is an overview of the subject matter to be described in detail in this specification. This overview is not intended to limit the scope of the claims.

[0004] This application aims to provide a highly conductive nanocarbon-coated current collector and a method for manufacturing the same in order to solve the problems presented in the above background art.

Means for Solving the Problems

[0005] To solve the above problems, this application provides a highly conductive nanocarbon-coated current collector comprising a current collector and highly conductive nanocarbon coating layers applied on both sides of the current collector, where the current collector is any one of copper foil, aluminum foil, and copper-aluminum alloy foil, The present invention provides a highly conductive nanocarbon coated current collector characterized in that the highly conductive nanocarbon coating layer is formed by applying a conductive adhesive and drying it.

[0006] Preferably, the total thickness of the highly conductive nanocarbon coated current collector is 3 to 20 μm, and the thickness of the current collector is 2 to 18 μm.

[0007] Preferably, the thickness of the highly conductive nanocarbon coating layer is 0.5 to 1 μm.

[0008] Preferably, the conductive adhesive comprises, by weight, 10 to 15 parts methyl methacrylate, 5 to 8 parts hydroxyethyl methacrylate, 3 to 5 parts vinyl acetate, 8 to 12 parts isobornyl methacrylate, 15 to 25 parts branched modified polyurethane acrylate resin, 0.1 to 0.3 parts initiator, 0.3 to 0.5 parts emulsifier, 10 to 25 parts conductive carbon material, 40 to 50 parts water, 0.5 to 1 part defoamer, 0.5 to 1 part dispersant, and 1 to 10 parts isopropyl alcohol.

[0009] Among these, the conductive carbon material is one of the following: conductive carbon black, CNTs, graphene, or carbon nanofibers.

[0010] Preferably, the method for preparing the branched modified polyurethane acrylate resin is: Step a involves dissolving p-phenylenediisocyanate in DMF, adding dibutyltin dilaurate, mixing uniformly, raising the temperature to 35-38°C, and after the temperature stabilizes, adding 1,3,5-cyclohexanetriol dropwise. After a incubation reaction under a nitrogen atmosphere for 1-2 hours, the temperature is raised to 75-80°C and the reaction continues for 4-6 hours. The temperature is then lowered to 45-55°C, bis(mercaptoethyl) sulfide is added dropwise, and the reaction is stirred for 1-1.5 hours. Subsequently, isophorone diisocyanate is added dropwise and the reaction continues for 2-4 hours. Then, pentaerythritol is added, the temperature is raised to 75-80°C and the reaction continues for 3-6 hours. Finally, the excess solvent is removed by rotary evaporation to obtain a branched polyurethane polyol. Step b includes dissolving isophorone diisocyanate and p-hydroxyanisole in DMF under the protection of a nitrogen atmosphere, raising the temperature to 45-50°C, adding dropwise the DMF solution in which hydroxypropyl methacrylate is dissolved, continuing the reaction at a constant temperature for 2-3 hours after the dropwise addition is complete, adding the branched polyurethane polyol prepared in step a, raising the temperature to 75-80°C, reacting for 4-8 hours, and then removing the excess solvent by vacuum evaporation to obtain a branched modified polyurethane acrylate resin.

[0011] Preferably, in step a, the molar ratio of p-phenylenediisocyanate, dibutyltin dilaurate, 1,3,5-cyclohexanetriol, bis(mercaptoethyl) sulfide, isophorone diisocyanate, and pentaerythritol is (2.5~3.2):(0.01~0.03):1:(2.5~3):(2.5~3):(2.2~3.2).

[0012] Preferably, in step b, the mass ratio of the isophorone diisocyanate, p-hydroxyanisole, hydroxypropyl methacrylate, and branched polyurethane polyol in molar parts is (1.8~2.1):(0.01~0.02):(1.1~1.4):(8~8.6).

[0013] Preferably, the initiator is azobisisobutyronitrile, the emulsifier is nonylphenol ethoxylate, the defoaming agent is a silicone defoaming agent, and the dispersant is sodium dodecylbenzenesulfonate.

[0014] A method for manufacturing a highly conductive nanocarbon coated current collector, Step S1 involves mixing methyl methacrylate, hydroxyethyl methacrylate, vinyl acetate, isobornyl methacrylate, and branched modified polyurethane acrylate resin, adding an emulsifier and water, stirring to mix uniformly, and obtaining an acrylic acid monomer emulsion. Step S2 involves dissolving the initiator in isopropyl alcohol to obtain an initiator dropping solution, raising the temperature of the acrylic acid monomer emulsion prepared in step S1 to 85-95°C, slowly adding the initiator dropping solution thereto, and after the dropping is complete, holding the temperature for 2-4 hours, then lowering the temperature to 30-45°C, adding the dispersant, defoamer, and conductive carbon material, and continuing to stir for 0.5-1 hour to obtain a conductive adhesive. A method for producing a highly conductive nanocarbon coated current collector, comprising step S3: applying a conductive adhesive to both sides of a current collector, raising the temperature to 105-120°C, drying for 2-4 minutes, and then obtaining a highly conductive nanocarbon coated current collector.

[0015] In this application, in order to enhance the conductivity of the highly conductive nanocarbon coating layer, a conductive adhesive is manufactured, and the amount of conductive carbon material added to it is increased to ensure the conductivity of the nanoconductive carbon coating layer. However, the addition of conductive carbon material reduces the viscosity and application performance of the conductive adhesive and affects its overall uniformity. Therefore, in order to avoid this phenomenon, this application further manufactures a branched modified polyurethane acrylate resin having a branched structure.

[0016] In this invention, first, 1,3,5-cyclohexanetriol is used as the core molecule, and it is added dropwise to p-phenylenediisocyanate and reacted to form a 3-arm compound with an isocyanate group at the end. This is then mixed with bis(mercaptoethyl) sulfide, and the order of addition is controlled to ensure that the end group of the reaction product is an active mercapto group. Further reaction with isophorone diisocyanate generates another reaction product with an isocyanate group at the end, which is then mixed again with pentaerythritol to finally form a branched polyurethane polyol with a hydroxyl group at the end.

[0017] Based on this, in this application, isophorone diisocyanate and hydroxypropyl methacrylate are further mixed, and an acrylic monomer having free isocyanate groups is prepared by limiting the dropwise addition order and reaction conditions. Subsequently, this is further mixed with a branched polyurethane polyol having a branched structure to produce a branched modified polyurethane acrylate resin. The branched modified polyurethane acrylate resin has a substantially spherical spatial structure, which can effectively reduce the viscosity of the adhesive and improve the dispersibility of conductive carbon materials in the adhesive. Furthermore, because the terminal groups of the branched modified polyurethane acrylate resin have a large number of active groups, a denser crosslinking network can be formed, improving the viscosity of the conductive adhesive. [Effects of the Invention]

[0018] Compared to the prior art, the beneficial effects achieved by this invention are as follows. This invention aims to manufacture a conductive adhesive with high conductivity in order to improve the conductivity of a current collector. To improve the conductivity of the conductive adhesive, this invention first increases the amount of conductive carbon material added. At the same time, in order to avoid performance degradation due to too much conductive carbon material, a branched modified polyurethane acrylate resin is prepared, and its substantially spherical spatial structure is used to reduce the viscosity of the entire adhesive, improve its fluidity, and improve the compatibility and dispersion performance of the conductive carbon material in the system. Furthermore, since the branched modified polyurethane acrylate resin also contains many acrylic groups, the complexity of the crosslinking network can be further improved, effectively increasing the viscosity of the adhesive and preventing a decrease in adhesive performance while improving conductivity.

[0019] After reading and understanding the detailed explanation, other points can be understood. [Modes for carrying out the invention]

[0020] The following clearly and completely describes the technical solutions in the embodiments of the present application. It is clear that the described embodiments are only a part of the embodiments of the present application, not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application. [Embodiment 1] The method for manufacturing a highly conductive nanocarbon-coated current collector includes the following steps.

[0021] S1: By weight parts, 10 parts of methyl methacrylate, 5 parts of hydroxyethyl methacrylate, 3 parts of vinyl acetate, 8 parts of isobornyl methacrylate and 15 parts of branched modified polyurethane acrylate resin are mixed, 0.3 parts of nonylphenol ethoxylate emulsifier and 80 parts of water are added, and stirred to be uniformly mixed to obtain an acrylic acid monomer emulsion. <�

[0022] Among them, the preparation method of the branched modified polyurethane acrylate resin includes the following steps.

[0023] a: In molar parts, 2.5 moles of p-phenylene diisocyanate are dissolved in DMF, 0.01 mole of dibutyltin dilaurate is added, and after uniformly mixing, the temperature is raised to 35 °C. After the temperature becomes constant, 1 mole of 1,3,5-cyclohexanetriol is dropped. Under the protection of a nitrogen atmosphere, after heat preservation reaction for 1 h, the temperature is raised to 75 °C, and the reaction is continued for 4 h. Then the temperature is lowered to 45 °C, 2.5 moles of bis(mercaptoethyl)sulfide are dropped, and after stirring reaction for 1 h, 2.5 moles of isophorone diisocyanate are continuously dropped. After reaction for 2 h, 2.2 moles of pentaerythritol are added, the temperature is raised to 75 °C, and after continuous reaction for 3 h, the excess solvent is removed by rotary evaporation to obtain a branched polyurethane polyol.

[0024] b: In the mass part, under the protection of a nitrogen atmosphere, 18 parts of isophorone diisocyanate and 0.1 part of p-hydroxyanisole were dissolved in DMF, the temperature was raised to 45 °C, and a DMF solution in which 11 parts of hydroxypropyl methacrylate was dissolved was dropped. After the dropping was completed, the reaction was continued for 2 h with heat preservation. 80 parts of the branched polyurethane polyol prepared in step a was added, the temperature was raised to 75 °C, and after reacting for 4 h, the excess solvent was removed by vacuum evaporation to obtain a branched modified polyurethane acrylate resin.

[0025] S2: By weight, 0.1 part of azobisisobutyronitrile initiator was dissolved in 1 part of isopropyl alcohol to obtain an initiator dropping solution. The acrylic monomer emulsion prepared in step S1 was heated to 85 °C, and the initiator dropping solution was slowly dropped therein. After the dropping was completed, the reaction was carried out for 2 h with heat preservation, then the temperature was lowered to 30 °C. 0.5 part of sodium dodecylbenzenesulfonate dispersant, 0.5 part of silicone defoamer and 55 parts of conductive carbon black were added, and after continuously stirring for 0.5 - 1 h, a conductive adhesive was obtained.

[0026] S3: The conductive adhesive was applied to both sides of the current collector, the temperature was raised to 105 °C, and after drying for 2 min, a highly conductive nanocarbon-coated current collector was obtained.

[0027] [Example 2] Compared with Example 1, in this example, the addition amount of the branched modified polyurethane acrylate resin in step S1 was increased.

[0028] The manufacturing method of the highly conductive nanocarbon-coated current collector includes the following steps.

[0029] S1: By weight, 10 parts of methyl methacrylate, 5 parts of hydroxyethyl methacrylate, 3 parts of vinyl acetate, 8 parts of isobornyl methacrylate and 25 parts of branched modified polyurethane acrylate resin were mixed, 0.3 part of nonylphenol ethoxylate emulsifier and 80 parts of water were added, and stirred to mix uniformly to obtain an acrylic monomer emulsion.

[0030] Among these, the method for preparing the branched modified polyurethane acrylate resin includes the following steps.

[0031] a: In a molar portion, 2.5 moles of p-phenylenediisocyanate were dissolved in DMF, 0.01 moles of dibutyltin dilaurate were added and mixed uniformly, then the temperature was raised to 35°C, and after the temperature stabilized, 1 mole of 1,3,5-cyclohexanetriol was added dropwise, and the reaction was maintained for 1 hour under the protection of a nitrogen atmosphere, then the temperature was raised to 75°C and the reaction continued for 4 hours, then the temperature was lowered to 45°C, 2.5 moles of bis(mercaptoethyl) sulfide were added dropwise, and the reaction was stirred for 1 hour, then 2.5 moles of isophorone diisocyanate were added dropwise and the reaction continued for 2 hours, then 2.2 moles of pentaerythritol were added, the temperature was raised to 75°C and the reaction continued for 3 hours, then the excess solvent was removed by rotary evaporation to obtain a branched polyurethane polyol.

[0032] b: Dissolve 18 parts by mass of isophorone diisocyanate and 0.1 parts p-hydroxyanisole in DMF under the protection of a nitrogen atmosphere, raise the temperature to 45°C, add dropwise the DMF solution containing 11 parts hydroxypropyl methacrylate, and continue the reaction at a constant temperature for 2 hours after the dropwise addition is complete. Add 80 parts of the branched polyurethane polyol prepared in step a, raise the temperature to 75°C, react for 4 hours, and then remove the excess solvent by vacuum evaporation to obtain a branched modified polyurethane acrylate resin.

[0033] S2: Dissolve 0.1 parts by weight of azobisisobutyronitrile initiator in 1 part of isopropyl alcohol to obtain an initiator dropping solution. Heat the acrylic acid monomer emulsion prepared in step S1 to 85°C, and slowly add the initiator dropping solution to it. After the dropping is complete, allow to retain heat for 2 hours, then cool to 30°C. Add 0.5 parts sodium dodecylbenzenesulfonate dispersant, 0.5 parts silicone defoamer, and 55 parts conductive carbon black, and continue stirring for 0.5 to 1 hour to obtain a conductive adhesive.

[0034] S3: Conductive adhesive was applied to both sides of the current collector, the temperature was raised to 105°C, and after drying for 2 minutes, a highly conductive nanocarbon coated current collector was obtained.

[0035] [Example 3] Compared to Example 2, the amount of p-phenylenediisocyanate added in step a was increased in this example.

[0036] A method for manufacturing a highly conductive nanocarbon coated current collector includes the following steps.

[0037] S1: Mix 10 parts by weight of methyl methacrylate, 5 parts of hydroxyethyl methacrylate, 3 parts of vinyl acetate, 8 parts of isobornyl methacrylate, and 25 parts of branched modified polyurethane acrylate resin. Add 0.3 parts of nonylphenol ethoxylate emulsifier and 80 parts of water, stir, and mix uniformly to obtain an acrylic acid monomer emulsion.

[0038] Among these, the method for preparing the branched modified polyurethane acrylate resin includes the following steps.

[0039] a: In the molar portion, 3.2 moles of p-phenylenediisocyanate were dissolved in DMF, 0.01 moles of dibutyltin dilaurate were added and mixed uniformly, then the temperature was raised to 35°C, and after the temperature stabilized, 1 mole of 1,3,5-cyclohexanetriol was added dropwise, and the reaction was maintained for 1 hour under the protection of a nitrogen atmosphere, then the temperature was raised to 75°C and the reaction continued for 4 hours, then the temperature was lowered to 45°C, 2.5 moles of bis(mercaptoethyl) sulfide were added dropwise, and the reaction was stirred for 1 hour, then 2.5 moles of isophorone diisocyanate were added dropwise and the reaction continued for 2 hours, then 2.2 moles of pentaerythritol were added, the temperature was raised to 75°C and the reaction continued for 3 hours, then the excess solvent was removed by rotary evaporation to obtain a branched polyurethane polyol.

[0040] b: Dissolve 18 parts by mass of isophorone diisocyanate and 0.1 parts p-hydroxyanisole in DMF under the protection of a nitrogen atmosphere, raise the temperature to 45°C, add dropwise the DMF solution containing 11 parts hydroxypropyl methacrylate, and continue the reaction at a constant temperature for 2 hours after the dropwise addition is complete. Add 80 parts of the branched polyurethane polyol prepared in step a, raise the temperature to 75°C, react for 4 hours, and then remove the excess solvent by vacuum evaporation to obtain a branched modified polyurethane acrylate resin.

[0041] S2: Dissolve 0.1 parts by weight of azobisisobutyronitrile initiator in 1 part of isopropyl alcohol to obtain an initiator dropping solution. Heat the acrylic acid monomer emulsion prepared in step S1 to 85°C, and slowly add the initiator dropping solution to it. After the dropping is complete, allow to retain heat for 2 hours, then cool to 30°C. Add 0.5 parts sodium dodecylbenzenesulfonate dispersant, 0.5 parts silicone defoamer, and 55 parts conductive carbon black, and continue stirring for 0.5 to 1 hour to obtain a conductive adhesive.

[0042] S3: Conductive adhesive was applied to both sides of the current collector, the temperature was raised to 105°C, and after drying for 2 minutes, a highly conductive nanocarbon coated current collector was obtained.

[0043] [Example 4] Compared to Example 2, this example increased the amount of bis(mercaptoethyl) sulfide added in step a.

[0044] A method for manufacturing a highly conductive nanocarbon coated current collector includes the following steps.

[0045] S1: Mix 10 parts by weight of methyl methacrylate, 5 parts of hydroxyethyl methacrylate, 3 parts of vinyl acetate, 8 parts of isobornyl methacrylate, and 25 parts of branched modified polyurethane acrylate resin. Add 0.3 parts of nonylphenol ethoxylate emulsifier and 80 parts of water, stir, and mix uniformly to obtain an acrylic acid monomer emulsion.

[0046] Among these, the method for preparing the branched modified polyurethane acrylate resin includes the following steps.

[0047] a: In the molar portion, 2.5 moles of p-phenylenediisocyanate were dissolved in DMF, 0.01 moles of dibutyltin dilaurate were added and mixed uniformly, then the temperature was raised to 35°C, and after the temperature stabilized, 1 mole of 1,3,5-cyclohexanetriol was added dropwise, and the reaction was maintained under a nitrogen atmosphere for 1 hour, then the temperature was raised to 75°C and the reaction continued for 4 hours, then the temperature was lowered to 45°C, 3 moles of bis(mercaptoethyl) sulfide were added dropwise, and the reaction was stirred for 1 hour, then 2.5 moles of isophorone diisocyanate were added dropwise and the reaction continued for 2 hours, then 2.2 moles of pentaerythritol were added, the temperature was raised to 75°C and the reaction continued for 3 hours, then the excess solvent was removed by rotary evaporation to obtain a branched polyurethane polyol.

[0048] b: Dissolve 18 parts by mass of isophorone diisocyanate and 0.1 parts p-hydroxyanisole in DMF under the protection of a nitrogen atmosphere, raise the temperature to 45°C, add dropwise the DMF solution containing 11 parts hydroxypropyl methacrylate, and continue the reaction at a constant temperature for 2 hours after the dropwise addition is complete. Add 80 parts of the branched polyurethane polyol prepared in step a, raise the temperature to 75°C, react for 4 hours, and then remove the excess solvent by vacuum evaporation to obtain a branched modified polyurethane acrylate resin.

[0049] S2: Dissolve 0.1 parts by weight of azobisisobutyronitrile initiator in 1 part of isopropyl alcohol to obtain an initiator dropping solution. Heat the acrylic acid monomer emulsion prepared in step S1 to 85°C, and slowly add the initiator dropping solution to it. After the dropping is complete, allow to retain heat for 2 hours, then cool to 30°C. Add 0.5 parts sodium dodecylbenzenesulfonate dispersant, 0.5 parts silicone defoamer, and 55 parts conductive carbon black, and continue stirring for 0.5 to 1 hour to obtain a conductive adhesive.

[0050] S3: Conductive adhesive was applied to both sides of the current collector, the temperature was raised to 105°C, and after drying for 2 minutes, a highly conductive nanocarbon coated current collector was obtained.

[0051] [Example 5] Compared to Example 2, the amount of pentaerythritol added in step a was increased in this example.

[0052] A method for manufacturing a highly conductive nanocarbon coated current collector includes the following steps.

[0053] S1: Mix 10 parts by weight of methyl methacrylate, 5 parts of hydroxyethyl methacrylate, 3 parts of vinyl acetate, 8 parts of isobornyl methacrylate, and 25 parts of branched modified polyurethane acrylate resin. Add 0.3 parts of nonylphenol ethoxylate emulsifier and 80 parts of water, stir, and mix uniformly to obtain an acrylic acid monomer emulsion.

[0054] Among these, the method for preparing the branched modified polyurethane acrylate resin includes the following steps.

[0055] a: In the molar portion, 2.5 moles of p-phenylenediisocyanate were dissolved in DMF, 0.01 moles of dibutyltin dilaurate were added and mixed uniformly, then the temperature was raised to 35°C, and after the temperature stabilized, 1 mole of 1,3,5-cyclohexanetriol was added dropwise, and the reaction was maintained under a nitrogen atmosphere for 1 hour, then the temperature was raised to 75°C and the reaction continued for 4 hours, then the temperature was lowered to 45°C, 2.5 moles of bis(mercaptoethyl) sulfide were added dropwise, and the reaction was stirred for 1 hour, then 2.5 moles of isophorone diisocyanate were added dropwise and the reaction continued for 2 hours, then 3.2 moles of pentaerythritol were added, the temperature was raised to 75°C and the reaction continued for 3 hours, then the excess solvent was removed by rotary evaporation to obtain a branched polyurethane polyol.

[0056] b: Dissolve 18 parts by mass of isophorone diisocyanate and 0.1 parts p-hydroxyanisole in DMF under the protection of a nitrogen atmosphere, raise the temperature to 45°C, add dropwise the DMF solution containing 11 parts hydroxypropyl methacrylate, and continue the reaction at a constant temperature for 2 hours after the dropwise addition is complete. Add 80 parts of the branched polyurethane polyol prepared in step a, raise the temperature to 75°C, react for 4 hours, and then remove the excess solvent by vacuum evaporation to obtain a branched modified polyurethane acrylate resin.

[0057] S2: Dissolve 0.1 parts by weight of azobisisobutyronitrile initiator in 1 part of isopropyl alcohol to obtain an initiator dropping solution. Heat the acrylic acid monomer emulsion prepared in step S1 to 85°C, and slowly add the initiator dropping solution to it. After the dropping is complete, allow to retain heat for 2 hours, then cool to 30°C. Add 0.5 parts sodium dodecylbenzenesulfonate dispersant, 0.5 parts silicone defoamer, and 55 parts conductive carbon black, and continue stirring for 0.5 to 1 hour to obtain a conductive adhesive.

[0058] S3: Conductive adhesive was applied to both sides of the current collector, the temperature was raised to 105°C, and after drying for 2 minutes, a highly conductive nanocarbon coated current collector was obtained.

[0059] [Example 6] A method for manufacturing a highly conductive nanocarbon coated current collector includes the following steps.

[0060] S1: Mix 15 parts by weight of methyl methacrylate, 8 parts of hydroxyethyl methacrylate, 5 parts of vinyl acetate, 12 parts of isobornyl methacrylate, and 25 parts of branched modified polyurethane acrylate resin. Add 0.5 parts of nonylphenol ethoxylate emulsifier and 100 parts of water, stir to mix uniformly, and obtain an acrylic acid monomer emulsion.

[0061] Among these, the method for preparing the branched modified polyurethane acrylate resin includes the following steps.

[0062] a: In a molar portion, 3.2 moles of p-phenylenediisocyanate were dissolved in DMF, 0.03 moles of dibutyltin dilaurate were added and mixed uniformly, then the mixture was heated to 38°C, and after the temperature stabilized, 1 mole of 1,3,5-cyclohexanetriol was added dropwise, and the mixture was incubated under a nitrogen atmosphere for 2 hours. Then the mixture was heated to 80°C and the reaction continued for 6 hours, then cooled to 55°C, 3 moles of bis(mercaptoethyl) sulfide were added dropwise, and the mixture was stirred for 1.5 hours. Then 3 moles of isophorone diisocyanate were added dropwise and the mixture was reacted for 4 hours, then 3.2 moles of pentaerythritol were added, the mixture was heated to 80°C and the reaction continued for 6 hours, and the excess solvent was removed by rotary evaporation to obtain a branched polyurethane polyol.

[0063] b: In part by mass, under the protection of a nitrogen atmosphere, 21 parts isophorone diisocyanate and 0.2 parts p-hydroxyanisole were dissolved in DMF, the temperature was raised to 50°C, and a DMF solution containing 14 parts hydroxypropyl methacrylate was added dropwise. After the dropwise addition was complete, the reaction was continued at a constant temperature for 3 hours, and 86 parts of the branched polyurethane polyol prepared in step a were added dropwise. The temperature was raised to 80°C, and the reaction was carried out for 8 hours. After that, the excess solvent was removed by vacuum evaporation to obtain a branched modified polyurethane acrylate resin.

[0064] S2: Dissolve 0.3 parts by weight of azobisisobutyronitrile initiator in 20 parts of isopropyl alcohol to obtain an initiator dropping solution. Heat the acrylic acid monomer emulsion prepared in step S1 to 95°C, and slowly add the initiator dropping solution to it. After the dropping is complete, allow to retain heat for 4 hours, then cool to 45°C. Add 1 part sodium dodecylbenzenesulfonate dispersant, 1 part silicone defoamer, and 75 parts conductive carbon black, and continue stirring for 1 hour to obtain a conductive adhesive.

[0065] S3: Conductive adhesive was applied to both sides of the current collector, the temperature was raised to 110°C, and after drying for 4 minutes, a highly conductive nanocarbon coated current collector was obtained.

[0066] [Comparative Example 1] In contrast to Example 1, in this comparative example, branched polyurethane acrylate resin was not prepared, and only an equal amount of PVDF was used as the adhesive.

[0067] A method for manufacturing a highly conductive nanocarbon coated current collector includes the following steps.

[0068] S1: Mix 41 parts by weight of PVDF and 80 parts of water, add 0.5 parts of sodium dodecylbenzenesulfonate dispersant, 0.5 parts of silicone defoamer, and 55 parts of conductive carbon black, and stir continuously for 0.5 to 1 hour to obtain a conductive adhesive.

[0069] S3: Conductive adhesive was applied to both sides of the current collector, the temperature was raised to 105°C, and after drying for 2 minutes, a highly conductive nanocarbon coated current collector was obtained.

[0070] measurement: The highly conductive nanocarbon coated current collectors produced in Examples 1-6 and Comparative Example 1 were manufactured as lithium batteries and measured as follows.

[0071] Magnification Performance 5C Test: Under a temperature of 25℃±5℃, the battery was charged with a constant current of 0.2C up to the limit voltage, then switched to constant voltage charging. Charging stopped when the cutoff current reached 0.01C, and then discharged with a current of 5C up to the termination voltage. The discharge capacity was obtained, and the capacity retention rate was calculated from the discharge capacity and initial capacity.

[0072] Cycle performance test: Under a temperature of 25°C ± 5°C, the battery was charged with a constant current of 1C up to the limit voltage, then switched to constant voltage charging, and charging stopped when the cutoff current reached 0.01C. The battery was discharged with a current of 1C up to the termination voltage, and the cycle was repeated 1000 times before stopping. The discharge capacity was obtained, and the capacity retention rate was calculated from the discharge capacity and initial capacity.

[0073] High-temperature performance test: Under a temperature of 25°C ± 5°C, the battery was charged with a constant current of 0.2C up to the limit voltage, then switched to constant voltage charging, and charging stopped when the cutoff current reached 0.01C. Then, under a temperature of 60°C ± 2°C, the current was left for 2 hours, and then the battery was discharged to the cutoff voltage at 1C, and the capacity retention rate was calculated.

[0074] Low-temperature performance test: Under a temperature of 25°C ± 5°C, the battery was charged with a constant current of 0.2C up to the limit voltage, then switched to constant voltage charging, and charging stopped when the cutoff current reached 0.01C. Then, under a temperature of 60°C ± 2°C, the current was left for 2 hours, and then the battery was discharged to the cutoff voltage at 1C, and the capacity retention rate was calculated.

[0075] The measurement results are shown in the table below.

[0076] [Table 1]

[0077] The foregoing are merely preferred embodiments of the present application and do not limit it. While the present application has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical proposals described in the above embodiments or replace some of their technical features with equivalents. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present application should be included within the scope of protection.

Claims

1. A highly conductive nanocarbon coated current collector comprising a current collector and highly conductive nanocarbon coating layers applied to both sides of the current collector, The current collector is made of one of the following: copper foil, aluminum foil, or copper-aluminum alloy foil. The aforementioned highly conductive nanocarbon coating layer is formed by applying a conductive adhesive and drying it. By weight, the conductive adhesive comprises 10 to 15 parts methyl methacrylate, 5 to 8 parts hydroxyethyl methacrylate, 3 to 5 parts vinyl acetate, 8 to 12 parts isobornyl methacrylate, 15 to 25 parts branched modified polyurethane acrylate resin, 0.1 to 0.3 parts initiator, 0.3 to 0.5 parts emulsifier, 55 to 75 parts conductive carbon material, 80 to 100 parts water, 0.5 to 1 part defoaming agent, 0.5 to 1 part dispersant, and 1 to 20 parts isopropyl alcohol. The conductive carbon material is one of the following: conductive carbon black, CNTs, graphene, or carbon nanofibers. Highly conductive nanocarbon coated current collector.

2. The total thickness of the highly conductive nanocarbon coated current collector is 3 to 20 μm, and the thickness of the current collector is 2 to 18 μm. The highly conductive nanocarbon coated current collector according to claim 1.

3. The thickness of the aforementioned highly conductive nanocarbon coating layer is 0.5 to 1 μm. A highly conductive nanocarbon coated current collector according to claim 1 or 2.

4. The initiator is azobisisobutyronitrile, the emulsifier is nonylphenol ethoxylate, the defoaming agent is a silicone defoaming agent, and the dispersant is sodium dodecylbenzenesulfonate. A highly conductive nanocarbon coated current collector according to any one of claims 1 to 3.

5. The method for preparing the branched modified polyurethane acrylate resin is as follows: Step a involves dissolving p-phenylenediisocyanate in DMF, adding dibutyltin dilaurate, mixing uniformly, raising the temperature to 35-38°C, and after the temperature stabilizes, adding 1,3,5-cyclohexanetriol dropwise. After a 1-2 hour incubation reaction under a nitrogen atmosphere, the temperature is raised to 75-80°C and the reaction continues for 4-6 hours. The temperature is then lowered to 45-55°C, bis(mercaptoethyl) sulfide is added dropwise, and a stirring reaction is carried out for 1-1.5 hours. Subsequently, isophorone diisocyanate is added dropwise and the reaction continues for 2-4 hours. Then, pentaerythritol is added, the temperature is raised to 75-80°C and the reaction continues for 3-6 hours. Finally, the excess solvent is removed by rotary evaporation to obtain a branched polyurethane polyol. Step b includes dissolving isophorone diisocyanate and p-hydroxyanisole in DMF under nitrogen atmosphere protection, raising the temperature to 45-50°C, adding dropwise the DMF solution in which hydroxypropyl methacrylate is dissolved, continuing the reaction for 2-3 hours after the dropwise addition is complete, adding the branched polyurethane polyol prepared in step a, raising the temperature to 75-80°C, reacting for 4-8 hours, and then removing the excess solvent by vacuum evaporation to obtain a branched modified polyurethane acrylate resin. A highly conductive nanocarbon coated current collector according to any one of claims 1 to 4.

6. In step a, the molar ratio of p-phenylenediisocyanate, dibutyltin dilaurate, 1,3,5-cyclohexanetriol, bis(mercaptoethyl) sulfide, isophorone diisocyanate, and pentaerythritol is (2.5-3.2):(0.01-0.03):1:(2.5-3):(2.5-3):(2.2-3.2). The highly conductive nanocarbon coated current collector according to claim 5.

7. In step b, the mass ratio of the isophorone diisocyanate, p-hydroxyanisole, hydroxypropyl methacrylate, and branched polyurethane polyol in molar portions is (1.8-2.1):(0.01-0.02):(1.1-1.4):(8-8.6). The highly conductive nanocarbon coated current collector according to claim 5 or 6.

8. Step S1 involves mixing methyl methacrylate, hydroxyethyl methacrylate, vinyl acetate, isobornyl methacrylate, and branched modified polyurethane acrylate resin, adding an emulsifier and water, stirring to mix uniformly, and obtaining an acrylic acid monomer emulsion. Step S2 involves dissolving the initiator in isopropyl alcohol to obtain an initiator dropping solution, raising the temperature of the acrylic acid monomer emulsion prepared in step S1 to 85-95°C, slowly adding the initiator dropping solution to it, and after the dropping is complete, holding the temperature for 2-4 hours, then lowering the temperature to 30-45°C, adding a dispersant, defoamer, and conductive carbon material, and stirring continuously for 0.5-1 hour to obtain a conductive adhesive. Step S3 includes applying a conductive adhesive to both sides of the current collector, raising the temperature to 105-120°C, drying for 2-4 minutes, and then winding it up to obtain a highly conductive nanocarbon coated current collector. A method for manufacturing a highly conductive nanocarbon coated current collector.

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