An ultralight flame-retardant negative electrode current collector and its preparation method
By preparing an ultralight and flame-retardant negative electrode current collector, and combining copper-plated conductive carbon nanomaterials and polyimide powder, the problems of high current collector density and flammability and explosion have been solved, thereby improving the energy density and safety of lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI INST OF SPACE POWER SOURCES
- Filing Date
- 2022-12-30
- Publication Date
- 2026-05-26
Smart Images
Figure BDA0004032363740000021 
Figure BDA0004032363740000031 
Figure BDA0004032363740000061
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery technology, and specifically relates to an ultralight flame-retardant negative electrode current collector and its preparation method. Background Technology
[0002] In recent years, lithium batteries have developed rapidly, and in addition to meeting the basic needs of consumers' daily lives, they are gradually emerging in the fields of large-scale energy storage equipment such as electric vehicles, aerospace, energy storage power stations, and smart grids. This has placed higher demands on the energy density and safety of lithium batteries.
[0003] Improving current collectors is crucial for enhancing the performance of lithium-ion batteries. Current collectors comprise 15%-18% of the weight of lithium-ion batteries, and reducing their density is an effective way to increase battery energy density. This is why battery manufacturers are constantly striving to reduce current collector thickness. However, ultra-thin current collectors sacrifice the conductivity, heat dissipation, and mechanical properties of the metal foil, which can actually reduce battery power density. Researchers have developed composite current collectors with metal layers coated on both sides of the polymer. Metal coatings are created on both sides of flexible polymers and plastics using methods such as vapor deposition and magnetron sputtering. These composites have a much lower density than pure metal current collectors and are more flexible, making them a promising candidate in the field of flexible batteries. However, they suffer from high manufacturing costs, limited production scale, and the tendency for the metal coating to peel off.
[0004] Furthermore, burrs on metal current collectors are a significant cause of internal short circuits in batteries, while the flammability and poor heat resistance of polymer current collectors pose safety hazards for lithium batteries. Therefore, ultralight flame-retardant current collectors have broad application prospects, provided that battery energy density and safety performance are improved. Summary of the Invention
[0005] In order to overcome the shortcomings of the existing technology, the inventors have conducted intensive research and provided an ultralight flame-retardant negative electrode current collector and its preparation method, which reduces the density of the current collector and ensures the conductivity, mechanical properties and safety performance of the current collector.
[0006] The technical solution provided by this invention is as follows:
[0007] Firstly, an ultralight flame-retardant negative electrode current collector is prepared from raw materials comprising the following parts by weight:
[0008]
[0009] The copper-plated conductive carbon nanomaterial is copper-plated conductive graphite and / or copper-plated carbon nanotubes.
[0010] Secondly, a method for preparing an ultralight flame-retardant negative electrode current collector includes the following steps:
[0011] 1. Pretreatment. The conductive carbon nanomaterials were boiled in NaOH solution, then washed with deionized water until neutral to remove surface oil. Next, they were roughened in a roughening solution, then sensitized in a sensitizing solution, and finally activated in an activation solution. After rinsing with distilled water, the pretreatment of the conductive carbon nanomaterials was completed.
[0012] 2. Reduction. The pretreated conductive carbon nanomaterials are added to a formaldehyde solution for reduction treatment.
[0013] 3. Electroless copper plating. The pre-reduced conductive carbon nanomaterials are added to the plating solution and stirred until a copper layer of a certain thickness is coated by the conductive carbon nanomaterials, thus completing the electroless copper plating of the conductive carbon nanomaterials.
[0014] 4. Passivation treatment. The copper-plated conductive carbon nanomaterials are added to a passivation solution for passivation treatment to prevent oxidation of the surface copper layer.
[0015] 5. Wet film coating. Mix polyimide powder, copper-plated conductive carbon nanomaterials, flame retardant, and dispersant in a certain proportion, add them to N,N-dimethylacetamide, stir thoroughly to form a uniform slurry, and then coat the substrate with a wet film.
[0016] 6. Preparation of negative electrode current collector. The plate coated with wet film is immersed in water, and the peeled wet film is removed and dried to obtain a lightweight flame-retardant negative electrode current collector.
[0017] The ultralight flame-retardant negative electrode current collector and its preparation method provided by the present invention have the following beneficial effects:
[0018] (1) The present invention provides an ultralight flame-retardant negative electrode current collector and its preparation method, which uses polyimide powder as the matrix, copper-plated conductive graphite and / or copper-plated carbon nanotubes as conductive fillers, and adds flame retardants, which can effectively reduce the density of the current collector and ensure the conductivity and safety performance of the current collector.
[0019] (2) The present invention provides an ultralight flame-retardant negative electrode current collector and its preparation method. The negative electrode current collector is obtained by wet film coating + drying. The drying method adopts a gradient heating method, drying the solvent at a lower temperature of 80-120℃, and further imidizing the polyimide powder at 180-250℃ to eliminate impurities.
[0020] (3) The present invention provides an ultralight flame-retardant negative electrode current collector and its preparation method. The negative electrode current collector is obtained by wet film coating + drying. The process is simple and ensures the mechanical properties of the current collector. Detailed Implementation
[0021] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.
[0022] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.
[0023] According to a first aspect of the present invention, an ultralight flame-retardant negative electrode current collector is provided, which is prepared from raw materials comprising the following parts by weight:
[0024]
[0025] The copper-plated conductive carbon nanomaterial is copper-plated conductive graphite and / or copper-plated carbon nanotubes.
[0026] The dispersant is at least one of polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and hexadecyltrimethylammonium bromide (CTAB).
[0027] The flame retardant is a phosphorus-based flame retardant or an aliphatic halogenated hydrocarbon, or an organic nitrogen-based flame retardant can be used in combination with a phosphorus-based flame retardant.
[0028] According to a second aspect of the present invention, a method for preparing an ultralight flame-retardant negative electrode current collector is provided, comprising the following steps:
[0029] Pretreatment. The conductive carbon nanomaterials were boiled in NaOH solution, then washed with deionized water until neutral to remove surface oil. Next, they were roughened in a roughening solution, then sensitized in a sensitizing solution, and finally activated in an activation solution and rinsed with distilled water.
[0030] The concentration of the NaOH solution is 20-30%. The roughening solution is a mixture of H₂SO₄, HNO₃, and their concentrations, with a concentration of 20-25%. The sensitizing solution is obtained by dissolving SnCl₂ powder in 35% hydrochloric acid, then diluting it with water to form the sensitizing solution. The SnCl₂ concentration is 10-20 g / L, and the hydrochloric acid mass fraction is 4%. A small amount of tin granules is added to prevent SnCl₂ oxidation. The activation solution is obtained by adding ammonia dropwise to a 1-2 g / L silver nitrate aqueous solution until the solution changes from brown to colorless and transparent.
[0031] Reduction. The pretreated conductive carbon nanomaterials are added to a formaldehyde solution with a concentration of 10-20 wt% for reduction treatment.
[0032] Chemical copper plating. Pre-reduced conductive carbon nanomaterials are added to the plating solution, and the mixture is slowly stirred magnetically until a copper layer of suitable thickness is formed. When the conductive carbon nanomaterial is conductive graphite, the proportion added to the plating solution is <1.5 g / L; when the conductive carbon nanomaterial is carbon nanotubes, the proportion added to the plating solution is <1 g / L. The components and concentrations in the plating solution are: disodium ethylenediaminetetraacetate 20-30 g / L, potassium sodium tartrate 20-30 g / L, sodium hydroxide 10-20 g / L, copper sulfate 15-25 g / L, and formaldehyde (37%) 25-35 mL / L. The preferred components and concentrations in the plating solution are: disodium ethylenediaminetetraacetate 25 g / L, potassium sodium tartrate 25 g / L, sodium hydroxide 15 g / L, copper sulfate 20 g / L, and formaldehyde (37%) 30 mL / L.
[0033] Passivation treatment. The copper-plated conductive carbon nanomaterials are added to a passivation solution for passivation treatment to prevent oxidation of the surface copper layer. The passivation solution is a benzotriazole solution with a concentration of 0.5-1 wt%.
[0034] Wet film coating. Polyimide powder, copper-plated conductive graphite, copper-plated carbon nanotubes, flame retardant, and dispersant are mixed in proportion and added to N,N-dimethylacetamide (DMAC). The mixture is stirred thoroughly to form a uniform slurry. A wet film is then coated onto a glass plate using a coating machine. The solid content of the wet film slurry is 20-30 wt%.
[0035] Preparation of the negative electrode current collector: A glass plate coated with a wet film is immersed in water for 6-18 hours. The peeled wet film is then removed and dried in a vacuum oven to obtain a lightweight, flame-retardant negative electrode current collector. Drying is performed using a gradient temperature method: holding at 80℃-120℃ for 30-60 minutes to evaporate the solvent DMAC, followed by holding at 180-250℃ for 60-90 minutes to completely imidize the polyimide powder, generating a polyimide-based ultralight flame-retardant negative electrode current collector.
[0036] Example
[0037] Example 1
[0038] 1. Pretreatment. Conductive graphite and carbon nanotubes were boiled in NaOH solution, then rinsed with deionized water until neutral to remove surface oil. Next, they were roughened in a roughening solution, then sensitized in a sensitizing solution, and finally activated in an activation solution. The mixture was rinsed thoroughly with distilled water. The NaOH solution concentration was 25%. The roughening solution was H₂SO₄ with a concentration of 25%. The sensitizing solution was obtained by dissolving SnCl₂ powder in 35% hydrochloric acid, then diluting with water to form a sensitizing solution with a SnCl₂ concentration of 15 g / L and a hydrochloric acid mass fraction of 4%. A small amount of tin granules was added to prevent SnCl₂ oxidation. The activation solution was obtained by adding ammonia dropwise to a 2 g / L silver nitrate aqueous solution until the solution changed from brown to colorless and transparent.
[0039] 2. Reduction. The pretreated conductive graphite and carbon nanotubes were added to a 15% formaldehyde solution for reduction treatment.
[0040] 3. Electroless Copper Plating. Pre-reduced conductive graphite and carbon nanotubes are added to the plating solution, and the mixture is slowly stirred magnetically until a copper layer of suitable thickness is formed. The proportion of conductive graphite added to the plating solution is 1 g / L, and the proportion of carbon nanotubes added is 0.5 g / L. The concentrations of each component in the plating solution are: disodium ethylenediaminetetraacetate 25 g / L, potassium sodium tartrate 25 g / L, sodium hydroxide 15 g / L, copper sulfate 20 g / L, and formaldehyde (37%) 30 mL / L.
[0041] 4. Passivation treatment. The copper-plated conductive graphite and carbon nanotubes are added to a passivation solution for passivation treatment to prevent oxidation of the surface copper layer. The passivation solution is a benzotriazole solution with a concentration of 1 wt%.
[0042] 5. Wet film coating. Polyimide powder, copper-plated conductive graphite, copper-plated carbon nanotubes, flame retardant triphenyl phosphate, and dispersant cetyltrimethylammonium bromide (CTAB) are mixed in a specific ratio and added to N,N-dimethylacetamide. The mixture is thoroughly stirred to form a homogeneous slurry, which is then coated onto a glass plate using a coating machine. The mass ratio of polyimide powder, copper-plated conductive graphite, copper-plated carbon nanotubes, dispersant, and flame retardant is 20:50:15:3:12, and the solid content of the wet film slurry is 25 wt%.
[0043] 6. Preparation of the negative electrode current collector. A glass plate coated with a wet film was immersed in water for 12 hours. The peeled-off wet film was then placed in a vacuum oven and dried to obtain a lightweight, flame-retardant negative electrode current collector. Drying was performed using a gradient temperature method: 80℃ for 60 minutes, followed by 200℃ for 90 minutes, to obtain a polyimide-based ultralight flame-retardant negative electrode current collector. The current collector performance results are shown in Table 1.
[0044] Example 2
[0045] Example 2 is identical to Example 1, except that the mass ratio of polyimide powder, copper-plated conductive graphite, copper-plated carbon nanotubes, dispersant, and flame retardant is 20:65:0:3:12. The current collector performance results are shown in Table 1.
[0046] Example 3
[0047] Example 3 is identical to Example 1, except that the mass ratio of polyimide powder, copper-plated conductive graphite, copper-plated carbon nanotubes, dispersant, and flame retardant is 20:0:63:5:12. The current collector performance results are shown in Table 1.
[0048] Comparative Example
[0049] Comparative Example 1
[0050] 1. Wet film coating. Polyimide powder, conductive graphite (unplated copper), carbon nanotubes (unplated copper), flame retardant triphenyl phosphate, and dispersant cetyltrimethylammonium bromide (CTAB) are mixed and added to N,N-dimethylacetamide. The mixture is thoroughly stirred to form a homogeneous slurry, which is then coated onto a glass plate using a coating machine. The mass ratio of polyimide powder, conductive graphite, carbon nanotubes, dispersant, and flame retardant is 20:50:15:3:12, and the solid content of the wet film slurry is 25 wt%.
[0051] 2. Preparation of the negative electrode current collector. A glass plate coated with a wet film was immersed in water for 12 hours. The peeled-off wet film was then placed in a vacuum oven and dried to obtain a lightweight, flame-retardant negative electrode current collector. Drying was performed using a gradient temperature method: holding at 80℃ for 60 minutes, then at 200℃ for 90 minutes, to obtain a polyimide-based ultralight flame-retardant negative electrode current collector. The current collector performance results are shown in Table 1.
[0052] Table 1 Performance results of the current collector
[0053]
[0054]
[0055] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
[0056] The contents not described in detail in this specification are common knowledge to those skilled in the art.
Claims
1. An ultralight flame-retardant negative electrode current collector, characterized in that, It is prepared from raw materials comprising the following parts by weight: 20 parts of polyimide powder; 60-70 parts of copper-plated conductive carbon nanomaterials; 1-5 parts dispersant; 10-15 parts flame retardant; The copper-plated conductive carbon nanomaterial is copper-plated conductive graphite and / or copper-plated carbon nanotubes. The dispersant is at least one of polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and hexadecyltrimethylammonium bromide (CTAB).
2. The ultralight flame-retardant negative electrode current collector according to claim 1, characterized in that, The flame retardant is at least one of phosphorus-based flame retardants, aliphatic halogenated hydrocarbons, organic nitrogen-based flame retardants, and phosphorus-based flame retardants.
3. A method for preparing the ultralight flame-retardant negative electrode current collector according to claim 1 or 2, characterized in that, Includes the following steps: Polyimide powder, copper-plated conductive carbon nanomaterials, flame retardant, and dispersant are mixed in proportion and added to N,N-dimethylacetamide. The mixture is stirred thoroughly to form a uniform slurry, which is then coated onto the board as a wet film. The board with the wet film coating is immersed in water, and the peeled wet film is removed and dried to obtain a lightweight flame-retardant negative electrode current collector.
4. The method for preparing the ultralight flame-retardant negative electrode current collector according to claim 3, characterized in that, The solid content of the wet film coated on the plate is 20-30 wt%.
5. The method for preparing the ultralight flame-retardant negative electrode current collector according to claim 3, characterized in that, In the step of immersing the coated wet film in water and then removing the peeled wet film for drying, the coated wet film is immersed in water for 6-18 hours.
6. The method for preparing the ultralight flame-retardant negative electrode current collector according to claim 3, characterized in that, In the step of immersing the coated wet film in water and then removing the peeled wet film for drying, the drying process adopts a gradient temperature method, holding at 80℃-120℃ for 30-60 minutes to evaporate the solvent N,N-dimethylacetamide, and then holding at 180-250℃ for 60-90 minutes to completely imidize the polyimide powder and generate a polyimide-based ultralight flame-retardant negative electrode current collector.
7. The method for preparing the ultralight flame-retardant negative electrode current collector according to claim 3, characterized in that, The preparation method further includes a step of preparing copper-plated conductive carbon nanomaterials, including: The conductive carbon nanomaterials were boiled in NaOH solution and then washed with deionized water until neutral to remove surface oil. Next, they were roughened in a roughening solution, sensitized in a sensitizing solution, and finally activated in an activation solution. After rinsing with distilled water, the pretreatment of the conductive carbon nanomaterials was completed. The pretreated conductive carbon nanomaterials were added to a formaldehyde solution for reduction treatment. The reduced conductive carbon nanomaterials are added to the plating solution and stirred until the conductive carbon nanomaterials coat a copper layer of a certain thickness, thus completing the chemical copper plating of the conductive carbon nanomaterials. The copper-plated conductive carbon nanomaterials are added to a passivation solution for passivation treatment to prevent oxidation of the surface copper layer.
8. The method for preparing the ultralight flame-retardant negative electrode current collector according to claim 7, characterized in that, In the pretreatment step, the concentration of the NaOH solution is 20-30%; and / or In the pretreatment step, the roughening solution is H2SO4, HNO3, or a mixture thereof, with a concentration of 20-25%; and / or In the pretreatment step, the sensitizing solution is obtained by dissolving SnCl2 powder in 35% hydrochloric acid, then diluting it with water to form the sensitizing solution. The SnCl2 concentration is 10-20 g / L, the hydrochloric acid mass fraction is 4%, and a small amount of tin granules is added to prevent SnCl2 oxidation; and / or In the pretreatment step, the activation solution is obtained by adding ammonia dropwise to a 1-2 g / L silver nitrate aqueous solution until the solution changes from brown to colorless and transparent; and / or In the reduction treatment step, the formaldehyde solution concentration is 10-20 wt%; and / or In the passivation treatment step, the passivation solution is a benzotriazole solution with a concentration of 0.5-1 wt%.
9. The method for preparing the ultralight flame-retardant negative electrode current collector according to claim 7, characterized in that, In the electroless copper plating step, when the conductive carbon nanomaterial is conductive graphite, the proportion added to the plating solution is <1.5 g / L; when the conductive carbon nanomaterial is carbon nanotubes, the proportion added to the plating solution is <1 g / L; and / or In the electroless copper plating step, the components and concentrations in the plating solution are as follows: disodium ethylenediaminetetraacetate 20-30 g / L, sodium potassium tartrate 20-30 g / L, sodium hydroxide 10-20 g / L, copper sulfate 15-25 g / L, and 37% formaldehyde 25-35 mL / L.