Negative current collector with carbon-containing functional layer and preparation method of negative current collector

Abstract

The invention discloses a negative current collector with a carbon-containing functional layer and a preparation method of the negative current collector, and relates to the technical field of current collectors. The negative current collector comprises a base material and a carbon-containing functional layer coated on the surface of the base material; the carbon-containing functional layer comprises the following raw materials in parts by weight: 40-50 parts of a carbon skeleton, 25-35 parts of a sodium-philic material, 18-24 parts of a binder and 0.5-2 parts of a surfactant; the binder is composed of a porous imidazolium-based binder and sulfonated-polyether ether ketone-Na in a mass ratio of (2-3): 1. According to the prepared negative electrode current collector, the energy density when the negative electrode current collector is used for a sodium ion battery is effectively improved, and risks caused by sodium dendrites generated by a negative electrode in the charging process are reduced.

Description

Technical Field

[0001] This invention relates to the field of current collector technology, specifically to a negative electrode current collector with a carbon functional layer and its preparation method. Background Technology

[0002] Sodium-free batteries use only the current collector as the negative electrode substrate. During cycling, sodium ions are deposited and removed from the current collector to complete the charge-discharge cycle, making it a novel high-energy-density energy storage battery system. In sodium-free batteries, the surface characteristics of the negative electrode current collector directly determine the deposition behavior of sodium metal and the battery performance.

[0003] In existing technologies, functional layers are typically added to the surface of the negative electrode current collector to regulate sodium deposition behavior. However, existing functional layers still have shortcomings in suppressing dendrite growth and improving energy density. On the one hand, the binder system in existing functional layers cannot simultaneously achieve ion conduction regulation and mechanical strength assurance. For example, patent CN120834143A discloses the use of traditional binders such as polyvinylidene fluoride and sodium carboxymethyl cellulose. However, since these polymers are electrochemically inert, they only play a physical fixing role and cannot guide uniform sodium deposition through ion transport regulation, which can lead to excessive local current density and dendrite growth. On the other hand, the lack of ion conduction function of binders leads to battery energy density loss. For example, patent CN118398827A discloses a coating material containing graphite, carbon nanotubes and binders. Although it can improve the uniformity of sodium deposition, the lack of ion conduction of the binder leads to the need to increase the thickness of the functional layer to ensure interface stability, resulting in a general capacity retention rate and a large energy density loss.

[0004] Therefore, in order to solve the problems mentioned above, it is of great significance to provide a negative electrode current collector with a carbon-containing functional layer. Summary of the Invention

[0005] The purpose of this invention is to provide a negative electrode current collector with a carbon-containing functional layer and its preparation method, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A negative electrode current collector having a carbon-containing functional layer, the negative electrode current collector comprising a substrate and a carbon-containing functional layer coated on the surface of the substrate; The raw materials for the carbon-containing functional layer, by weight, are: 40-50 parts carbon skeleton, 25-35 parts sodium-loving material, 18-24 parts binder, and 0.5-2 parts surfactant; The adhesive is composed of a porous imidazole onium-based adhesive and sulfonated polyether ether ketone-Na in a mass ratio of (2~3):1.

[0007] The surfactant is an anionic surfactant, which includes, but is not limited to, sodium dodecylbenzenesulfonate.

[0008] A more optimized method for preparing the porous imidazole-onium-based adhesive is as follows: Step 1: 3-(methacryloyloxy)propyltrimethoxysilane, thiazolyl silane and multi-walled carbon nanotubes are added sequentially to an aqueous ethanol solution. The temperature is set at 60~80℃, the mixture is stirred until homogeneous, and kept for 24~48 hours to obtain double bond-multi-walled carbon nanotubes. Step 2: Under a nitrogen atmosphere, 3-octyl-1-vinylimidazolium bromide, divinylbenzene, AIBN, and double-bond multi-walled carbon nanotubes were added sequentially to an ethyl acetate-ethanol-water solution. The temperature was set at 70~80℃, and the reaction was stirred for 22~26 hours. The mixture was then filtered, washed, and dried to obtain polymer-modified multi-walled carbon nanotubes. Step 3: Add polymer-modified multi-walled carbon nanotubes and sodium bis(fluorosulfonyl)imide to anhydrous methanol, stir at room temperature for 3.5 to 4.5 days, filter, wash and dry to obtain porous imidazole onium-based binder.

[0009] In a more optimized manner, the raw materials for the double bond-multi-walled carbon nanotubes, by weight, are: 0.8 to 1.2 parts of 3-(methacryloyloxy)propyltrimethoxysilane, 0.1 to 0.2 parts of thiazolyl silane, and 1 to 2 parts of multi-walled carbon nanotubes; The raw materials for the polymer-modified multi-walled carbon nanotubes, by weight, are: 4.5-6.5 parts of 3-octyl-1-vinylimidazolium bromide, 2.5-3.5 parts of divinylbenzene, 0.8-1.0 parts of AIBN, and 0.2-0.4 parts of double bond-multi-walled carbon nanotubes. The raw materials of the porous imidazole onium-based binder, by weight, are: 0.25~0.35 parts polymer-modified multi-walled carbon nanotubes and 0.25~0.35 parts sodium bis(fluorosulfonyl)imide.

[0010] A more optimized method for preparing the thiazolyl silane is as follows: under a nitrogen atmosphere, 2-aminothiazole is added to anhydrous tetrahydrofuran, the temperature is set to 45~55℃, and the mixture is stirred. Then, propyltriethoxysilane is added, and the mixture is stirred for 1.5~2.5 hours. The mixture is then distilled, eluted, and rotary evaporated to obtain the thiazolyl silane.

[0011] In a more optimized manner, the mass ratio of 2-aminothiazole to propyltriethoxysilane in the thiazolylsilane-containing raw material is (9~11):(24~26). The eluent used for elution consists of acetone and petroleum ether in a volume ratio of (0.8~1.2):(1.8~2.2).

[0012] A more optimized method for preparing the sulfonated-polyetheretherketone-Na is as follows: Step 1: Add 4,4'-(2-pyridinemethyl)bisphenol, difluorobenzophenone, potassium carbonate, and sodium carbonate sequentially to a sulfolane-toluene aqueous solution. Under nitrogen protection, set the temperature to 130~160°C and keep it at that temperature for 1~2 hours. Then raise the temperature to 190~220°C and keep it at that temperature for 2~4 hours. After hot water precipitation, washing, filtration, and drying, pyridine-polyether ether ketone is obtained. Step 2: Add concentrated sulfuric acid dropwise to pyridine-polyether ether ketone, stir, set the temperature to 55~65℃ and stir for 22~26 hours, quench with cold water, filter, dialyze, purify and concentrate to obtain sulfonated modified polyether ether ketone; Step 3: Add the sulfonated modified polyether ether ketone to deionized water, neutralize to neutral with 0.4~0.6mol / L sodium hydroxide solution, dialyze to obtain sulfonated-polyether ether ketone-Na.

[0013] In a more optimized manner, the raw materials of the pyridine-polyether ether ketone contain, by weight: 2-4 parts of 4,4'-(2-pyridinemethyl)bisphenol, 4-6 parts of difluorobenzophenone, 1-3 parts of potassium carbonate, and 1-3 parts of sodium carbonate. The raw materials for the sulfonated modified polyether ether ketone consist of, by weight, 28-32 parts concentrated sulfuric acid and 1-2 parts pyridine-polyether ether ketone.

[0014] More preferably, the carbon framework includes one or more of hard carbon, soft carbon, carbon fiber, carbon nanofiber, graphene, carbon nanotube, and three-dimensional porous carbon.

[0015] Ideally, the substrate is copper foil with a thickness of 10-20 μm; the areal density of the carbon-containing functional layer is 1.0-1.5 mg / cm³. 2 .

[0016] A method for preparing a negative electrode current collector with a carbon functional layer includes the following steps: Step 1: Add the carbon skeleton, sodium-loving material, binder, and surfactant to the solvent in sequence, and stir evenly to obtain a carbon-containing functional slurry; Step 2: Coat the carbon-containing functional slurry onto the substrate, dry it to form a carbon-containing functional layer; roll press to obtain the negative electrode current collector.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention constructs a three-dimensional conductive composite system by building a carbon-containing functional layer on the surface of a substrate, which effectively suppresses the risk of dendrite formation caused by sodium metal anode and improves the energy density of the battery. The binder system of the functional layer is composed of sulfonated polyether ether ketone-Na and porous imidazole onium-based binder. The two together construct a three-dimensional ion conduction network and a porous buffer framework, which effectively improves the electrical performance and cycle stability of sodium battery.

[0018] Among them, the imidazolium cations in the porous imidazolium-based binder homogenize the distribution of sodium ion flow through electrostatic shielding, guide the uniform deposition of sodium metal, and inhibit dendrite nucleation. In addition, its three-dimensional porous structure provides a buffer space for the volume expansion of sodium-loving metals during charging and discharging, avoiding coating cracking and irregular deposition of sodium metal caused by stress concentration, and can physically block the penetration growth of dendrites. Furthermore, the imidazolium cations form coordination and electrostatic interactions with the oxide layer and metal sites on the surface of sodium-loving materials, promoting the anchoring of particles and uniform dispersion, and constructing ion conduction channels on its surface to guide the uniform reduction and deposition of sodium ions.

[0019] However, since the polymer binder itself is an insulating material, double-bond multi-walled carbon nanotubes are introduced. During the preparation process, 3-(methacryloyloxy)propyltrimethoxysilane and thiazolium-containing silanes introduce thiazole groups and polymerizable double bonds on the surface of the multi-walled carbon nanotubes. The polar effect of the thiazole groups effectively improves the dispersibility of the multi-walled carbon nanotubes, preventing their aggregation and thus constructing a continuous three-dimensional conductive network. This balances the current density at the electrode interface, preventing the induction of sodium dendrites due to excessive local current density and heat generation. Furthermore, the N and S atoms on the thiazole groups provide additional Na⁺ nucleation sites, which, in conjunction with the imidazolium cation-dominated ion conduction channels, synergistically enhance ion transport efficiency, improve nucleation uniformity, reduce nucleation overpotential, and inhibit sodium dendrite growth. The polymerizable double bonds ensure that the nanotubes are anchored within the porous polymer framework during subsequent free radical copolymerization. It is important to note that 3-(methacryloyloxy)propyltrimethoxysilane is the main component for constructing the cross-linked network and anchoring carbon nanotubes, and the amount added must be sufficient to provide polymerizable sites. Thiazole-containing silanes are functional components, and excessive addition will occupy the active sites on the surface of carbon nanotubes, reduce the double bond grafting efficiency, and destroy the polymerization cross-linking and structural stability. Therefore, the amount of thiazolyl silane added needs to be controlled to be less than that of 3-(methacryloyloxy)propyltrimethoxysilane to balance the stability of polymerization and the synergy of functions.

[0020] Sulfonated polyetheretherketone-Na, as another binder component, forms a functional complement to the imidazolium-based polymer. In sulfonated polyetheretherketone-Na, polyetheretherketone imparts excellent mechanical strength and thermal stability to the functional layer, ensuring the structural integrity of the coating during long-term cycling and preventing energy density reduction due to structural damage and interface detachment. Simultaneously, the sodium-based sodium salting of the sulfonic acid groups forms highly efficient dissociative ion transport sites, enabling the polymer backbone itself to possess continuous low-resistance sodium ion conduction capability, significantly reducing electrode interface polarization and improving battery energy density. Furthermore, the nitrogen coordination sites on the pyridine ring enhance the interfacial bonding between the functional layer and the sodium-loving metal, guiding uniform sodium deposition and reducing capacity loss caused by dendrite formation, thus mitigating energy density decay. It is important to note that because the construction of the porous structure requires a sufficient polymer matrix to maintain porosity and backbone continuity, and the double-bonded multi-walled carbon nanotubes need to be anchored within the porous backbone to enhance conductivity, the amount of porous imidazolium-based binder in the binder system is higher than that of sulfonated polyetheretherketone-Na. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the following embodiments, the parts are by weight; it should be noted that there are no special restrictions on the purchase manufacturers of all the raw materials involved in this invention, and they include, for example, multi-walled carbon nanotubes (diameter of 20nm), sodium bis(fluorosulfonyl)imide (CAS: 100669-96-3), and carbon nanofibers (diameter of 100nm and length of 15μm).

[0023] Pre-preparation: I. Preparation of thiazolyl silanes: Under a nitrogen atmosphere, 10 parts of 2-aminothiazole were added to 100 parts of anhydrous tetrahydrofuran, the temperature was set to 50°C, and the mixture was stirred. Then, 25 parts of propyltriethoxysilane was added, and the mixture was stirred for another 2 hours. The mixture was then distilled, and eluted with acetone and petroleum ether in a volume ratio of 1:2 and rotary evaporated to obtain thiazolyl silanes.

[0024] II. Preparation of porous imidazolium-based binders: Step 1: Add 1 part of 3-(methacryloyloxy)propyltrimethoxysilane, 0.15 parts of thiazolylsilane and 1.5 parts of multi-walled carbon nanotubes to 50 parts of ethanol aqueous solution (ethanol to water volume ratio of 9:1) in sequence, set the temperature to 75℃, stir evenly, and keep for 36 hours to obtain double bond-multi-walled carbon nanotubes. Step 2: Under a nitrogen atmosphere, 5.5 parts of 3-octyl-1-vinylimidazolium bromide, 3 parts of divinylbenzene, 0.9 parts of AIBN, and 0.3 parts of double-bond multi-walled carbon nanotubes were added sequentially to 60 parts of ethyl acetate-ethanol-water solution (ethyl acetate, ethanol, and water volume ratio of 1:1:0.2). The temperature was set at 75℃, and the mixture was stirred for 24 hours. After filtration, washing, and drying, polymer-modified multi-walled carbon nanotubes were obtained. Step 3: Add 0.3 parts of polymer-modified multi-walled carbon nanotubes and 0.3 parts of sodium bis(fluorosulfonyl)imide to 50 parts of anhydrous methanol, stir at room temperature for 4 days, filter, wash and dry to obtain porous imidazole onium-based binder.

[0025] III. Preparation of sulfonated polyether ether ketone-Na: Step 1: Add 3 parts of 4,4'-(2-pyridinemethyl)bisphenol, 5 parts of difluorobenzophenone, 2 parts of potassium carbonate, and 2 parts of sodium carbonate to 90 parts of sulfolane-toluene-water solution (the volume ratio of sulfolane, toluene, and water is 72:13.5:4.5). Under nitrogen protection, set the temperature to 145°C and keep it at that temperature for 1.5 hours. Then raise the temperature to 200°C and keep it at that temperature for 3 hours. After hot water precipitation, washing, filtering, and drying, pyridine-polyether ether ketone is obtained. Step 2: Add 30 parts of concentrated sulfuric acid to 1.5 parts of pyridine-polyether ether ketone, stir, set the temperature to 60℃ and stir for 24 hours, quench with cold water, filter, dialyze, purify and concentrate to obtain sulfonated modified polyether ether ketone. Step 3: Add the sulfonated modified polyether ether ketone to deionized water, neutralize to neutral with 0.5 mol / L sodium hydroxide solution, and dialyze to obtain sulfonated-polyether ether ketone-Na.

[0026] Example 1: A method for preparing a negative electrode current collector with a carbon functional layer, specifically including the following steps: Step 1: Add 45 parts of carbon skeleton (carbon nanofibers), 30 parts of sodium-loving material (Sb metal element, particle size 100nm), 21 parts of binder (composed of porous imidazole onium-based binder and sulfonated polyether ether ketone-Na in a mass ratio of 2.5:1), and 1.2 parts of surfactant (sodium dodecylbenzenesulfonate) to the solvent (water) in sequence, stir evenly, and obtain carbon-containing functional slurry; Step 2: Coat a 20μm thick copper foil substrate with a carbon-containing functional paste, dry it, and form an areal density of 1.2 mg / cm³. 2 The carbon-containing functional layer is formed; the process parameters for rolling are: rolling speed of 3.5 m / min and linear pressure of 90 kgf / cm, to obtain the negative electrode current collector.

[0027] Example 2: A method for preparing a negative electrode current collector with a carbon functional layer, specifically including the following steps: Step 1: Add 40 parts of carbon skeleton (carbon nanofibers), 25 parts of sodium-loving material (Sb metal element, particle size 100nm), 21 parts of binder (composed of porous imidazole onium-based binder and sulfonated polyether ether ketone-Na in a mass ratio of 2:1) and 0.5 parts of surfactant (sodium dodecylbenzenesulfonate) to the solvent (water) in sequence, stir evenly, and obtain carbon-containing functional slurry; Step 2: Coat a 20μm thick copper foil substrate with a carbon-containing functional paste, dry it, and form an areal density of 1.0 mg / cm³. 2 The carbon-containing functional layer is formed; the process parameters for rolling are: rolling speed of 3.5 m / min and linear pressure of 90 kgf / cm, to obtain the negative electrode current collector.

[0028] Example 3: A method for preparing a negative electrode current collector with a carbon functional layer, specifically including the following steps: Step 1: Add 50 parts of carbon skeleton (carbon nanofibers), 35 parts of sodium-loving material (Sb metal element, particle size 100nm), 21 parts of binder (composed of porous imidazole onium-based binder and sulfonated polyether ether ketone-Na in a mass ratio of 3:1) and 2 parts of surfactant (sodium dodecylbenzenesulfonate) to the solvent (water) in sequence, stir evenly, and obtain carbon-containing functional slurry; Step 2: Coat a 20μm thick copper foil substrate with a carbon-containing functional paste, dry it, and form an areal density of 1.5mg / cm². 2 The carbon-containing functional layer is formed; the process parameters for rolling are: rolling speed of 3.5 m / min and linear pressure of 90 kgf / cm, to obtain the negative electrode current collector.

[0029] Example 4: Based on Example 1, the proportion of porous imidazole onium-based binder was increased, while the rest remained the same as in Example 1. The specific steps are as follows: Step 1: Add 45 parts of carbon skeleton (carbon nanofibers), 30 parts of sodium-loving material (Sb metal element, particle size 100nm), 21 parts of binder (composed of porous imidazole onium-based binder and sulfonated polyether ether ketone-Na in a mass ratio of 2.7:1), and 1.2 parts of surfactant (sodium dodecylbenzenesulfonate) to the solvent (water) in sequence, stir evenly, and obtain carbon-containing functional slurry; Step 2: Coat a 20μm thick copper foil substrate with a carbon-containing functional paste, dry it, and form an areal density of 1.2 mg / cm³. 2 The carbon-containing functional layer is formed; the process parameters for rolling are: rolling speed of 3.5 m / min and linear pressure of 90 kgf / cm, to obtain the negative electrode current collector.

[0030] Example 5: Based on Example 1, the proportion of porous imidazole onium-based binder was reduced, while the rest remained the same as in Example 1. The specific steps are as follows: Step 1: Add 45 parts of carbon skeleton (carbon nanofibers), 30 parts of sodium-loving material (Sb metal element, particle size 100nm), 21 parts of binder (composed of porous imidazole onium-based binder and sulfonated polyether ether ketone-Na in a mass ratio of 2.3:1), and 1.2 parts of surfactant (sodium dodecylbenzenesulfonate) to the solvent (water) in sequence, stir evenly, and obtain carbon-containing functional slurry; Step 2: Coat a 20μm thick copper foil substrate with a carbon-containing functional paste, dry it, and form an areal density of 1.2 mg / cm³. 2 The carbon-containing functional layer is formed; the process parameters for rolling are: rolling speed of 3.5 m / min and linear pressure of 90 kgf / cm, to obtain the negative electrode current collector.

[0031] Comparative Example 1: Based on Example 1, the adhesive composition was adjusted to exclude porous imidazole onion-based adhesive, while the rest remained the same as in Example 1.

[0032] Comparative Example 2: Based on Example 1, the mass ratio between the porous imidazole onium-based binder and sulfonated-polyether ether ketone-Na was adjusted to 1:2.5, while the rest remained the same as in Example 1.

[0033] Comparative Example 3: Based on Example 1, the imidazole-onium polymer composition was adjusted, but double-bonded multi-walled carbon nanotubes were not added, while the rest remained the same as in Example 1.

[0034] Comparative Example 4: Based on Example 1, the sulfonated-polyetheretherketone-Na component was adjusted, wherein no sodium salting treatment was performed, and the rest remained the same as in Example 1.

[0035] Comparative Example 5: Based on Example 1, the mass ratio between 3-(methacryloyloxy)propyltrimethoxysilane and thiazolylsilane was adjusted to 0.15:1, while the rest remained the same as in Example 1.

[0036] Comparative Example 6: Based on Example 1, using conventional adhesive PVDF as the adhesive, the rest is the same as in Example 1.

[0037] Performance testing: The negative electrode current collectors prepared in Examples 1-5 and Comparative Examples 1-6 were cut into circular pieces with a diameter of 12 mm; in a glove box under an argon atmosphere, a button cell (CR2025) was assembled in the following order: negative electrode shell - spring piece - gasket - negative electrode current collector - separator - electrolyte - positive electrode sheet - positive electrode shell. The separator was made of glass fiber, the electrolyte was 1M sodium hexafluorophosphate dissolved in diethylene glycol dimethyl ether solution, and the positive electrode sheet was made of sodium sheet. (1) Initial Coulombic Efficiency Test: The button cell (CR2025) was subjected to constant current charge and discharge test in the voltage range of 0.01~3V, and the initial charge specific capacity and initial discharge specific capacity were recorded; the initial coulombic efficiency was calculated according to the calculation formula: Initial Coulombic Efficiency (%) = Initial Discharge Specific Capacity / Initial Charge Specific Capacity × 100%; (2) Capacity retention test: The button cell (CR2025) was tested at a current density of 0.05 A·g -1 Under 200 cycles of constant current charge and discharge, the average coulombic efficiency is calculated using the formula: Coulombic efficiency = (discharge capacity / charge capacity) × 100%; (3) Discharge capacity test: The button cell (CR2025) was tested at a current density of 0.5 A·g -1 The system was subjected to 200 cycles of constant current charge and discharge, and the discharge capacity on the 200th cycle was recorded.

[0038]

[0039] Conclusion: The data in the table show that the sodium-free batteries prepared in Examples 1-5 exhibit good coulombic efficiency and mass energy density. Comparative Example 1 lacks porous imidazole-onium polymers, resulting in a lack of core nucleation sites and porous support structures. This significantly increases sodium nucleation resistance, raises the nucleation overpotential, and, due to the absence of uniform nucleation guidance, increases side reactions, decreases coulombic efficiency, reduces active sodium utilization, and ultimately leads to a decrease in discharge capacity. In Comparative Example 2, the ratio of porous imidazole-onium binder to sulfonated polyether ether ketone-Na is unbalanced. The porous imidazole-onium binder cannot fully exert its nucleation guiding role, thus reducing the ion conduction efficiency of sulfonated polyether ether ketone-Na, leading to an increase in nucleation overpotential and a decrease in both coulombic efficiency and mass energy density. In Comparative Example 3, without the addition of double-bonded multi-walled carbon nanotubes, the electron transport path and ion... The interruption of electron conduction channels and uneven electron / ion distribution during sodium deposition easily lead to local current accumulation, increased nucleation overpotential, and exacerbated side reactions, resulting in decreased coulombic efficiency and discharge capacity. In Comparative Example 5, the amount of 3-(methacryloyloxy)propyltrimethoxysilane added was too low, failing to provide sufficient polymerizable double bonds for multi-walled carbon nanotubes. This resulted in the carbon nanotubes not being effectively anchored in the polymer backbone, causing the conductive network to break and the interfacial bonding force to decrease, thereby increasing the nucleation overpotential and significantly reducing coulombic efficiency and discharge capacity. In Comparative Example 6, the use of a traditional PVDF binder resulted in weak interfacial interaction between the two, allowing sodium dendrites to easily penetrate the interface and react with the electrolyte, leading to a significant decrease in performance. In summary, this invention, by constructing a composite binder system, effectively reduces the nucleation overpotential, improves coulombic efficiency, capacity retention, and energy density, and endows the anode-free sodium battery with excellent electrical performance.

[0040] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A negative electrode current collector having a carbon-containing functional layer, characterized in that: The negative electrode current collector includes a substrate and a carbon-containing functional layer coated on the surface of the substrate; The raw materials of the carbon-containing functional layer, by weight, are: 40-50 parts carbon skeleton, 25-35 parts sodium-loving material, 18-24 parts binder, and 0.5-2 parts surfactant; The adhesive is composed of a porous imidazole onium-based adhesive and sulfonated polyether ether ketone-Na in a mass ratio of (2~3):

1.

2. The negative electrode current collector with a carbon-containing functional layer according to claim 1, characterized in that: The preparation method of the porous imidazolium-based adhesive is as follows: Step 1: 3-(methacryloyloxy)propyltrimethoxysilane, thiazolyl silane and multi-walled carbon nanotubes are added sequentially to an aqueous ethanol solution. The temperature is set at 60~80℃, the mixture is stirred until homogeneous, and kept for 24~48 hours to obtain double bond-multi-walled carbon nanotubes. Step 2: Under a nitrogen atmosphere, 3-octyl-1-vinylimidazolium bromide, divinylbenzene, AIBN, and double-bond multi-walled carbon nanotubes were added sequentially to an ethyl acetate-ethanol-water solution. The temperature was set at 70~80℃, and the reaction was stirred for 22~26 hours. The mixture was then filtered, washed, and dried to obtain polymer-modified multi-walled carbon nanotubes. Step 3: Add polymer-modified multi-walled carbon nanotubes and sodium bis(fluorosulfonyl)imide to anhydrous methanol, stir at room temperature for 3.5 to 4.5 days, filter, wash and dry to obtain porous imidazole onium-based binder.

3. The negative electrode current collector with a carbon-containing functional layer according to claim 2, characterized in that: The raw materials for the double bond-multi-walled carbon nanotubes, by weight, are: 0.8-1.2 parts of 3-(methacryloyloxy)propyltrimethoxysilane, 0.1-0.2 parts of thiazolyl silane, and 1-2 parts of multi-walled carbon nanotubes; The raw materials for the polymer-modified multi-walled carbon nanotubes, by weight, are: 4.5-6.5 parts of 3-octyl-1-vinylimidazolium bromide, 2.5-3.5 parts of divinylbenzene, 0.8-1.0 parts of AIBN, and 0.2-0.4 parts of double bond-multi-walled carbon nanotubes. The raw materials of the porous imidazole onium-based binder, by weight, are: 0.25~0.35 parts polymer-modified multi-walled carbon nanotubes and 0.25~0.35 parts sodium bis(fluorosulfonyl)imide.

4. The negative electrode current collector with a carbon-containing functional layer according to claim 2, characterized in that: The method for preparing the thiazolyl silane is as follows: under a nitrogen atmosphere, 2-aminothiazole is added to anhydrous tetrahydrofuran, the temperature is set at 45~55℃, and the mixture is stirred. Then, propyltriethoxysilane is added, and the mixture is stirred for 1.5~2.5 hours. The mixture is then distilled, eluted, and rotary evaporated to obtain the thiazolyl silane.

5. A negative electrode current collector with a carbon-containing functional layer according to claim 4, characterized in that: In the raw material containing thiazolyl silane, the mass ratio of 2-aminothiazolyl to propyltriethoxysilane is (9~11):(24~26). The eluent used for elution consists of acetone and petroleum ether in a volume ratio of (0.8~1.2):(1.8~2.2).

6. The negative electrode current collector with a carbon functional layer according to claim 1, characterized in that: The preparation method of the sulfonated-polyetheretherketone-Na is as follows: Step 1: Add 4,4'-(2-pyridinemethyl)bisphenol, difluorobenzophenone, potassium carbonate, and sodium carbonate sequentially to a sulfolane-toluene aqueous solution. Under nitrogen protection, set the temperature to 130~160°C and keep it at that temperature for 1~2 hours. Then raise the temperature to 190~220°C and keep it at that temperature for 2~4 hours. After hot water precipitation, washing, filtration, and drying, pyridine-polyether ether ketone is obtained. Step 2: Add concentrated sulfuric acid dropwise to pyridine-polyether ether ketone, stir, set the temperature to 55~65℃ and stir for 22~26 hours, quench with cold water, filter, dialyze, purify and concentrate to obtain sulfonated modified polyether ether ketone; Step 3: Add the sulfonated modified polyether ether ketone to deionized water, neutralize to neutral with 0.4~0.6mol / L sodium hydroxide solution, dialyze to obtain sulfonated-polyether ether ketone-Na.

7. A negative electrode current collector with a carbon-containing functional layer according to claim 6, characterized in that: The raw materials of the pyridine-polyether ether ketone contain, by weight: 2-4 parts of 4,4'-(2-pyridinemethyl)bisphenol, 4-6 parts of difluorobenzophenone, 1-3 parts of potassium carbonate, and 1-3 parts of sodium carbonate. The sulfonated polyether ether ketone raw material comprises, by weight: 28-32 parts concentrated sulfuric acid and 1-2 parts pyridine-polyether ether ketone.

8. A negative electrode current collector with a carbon functional layer according to claim 1, characterized in that: The carbon framework includes one or more of hard carbon, soft carbon, carbon fiber, carbon nanofiber, graphene, carbon nanotube, and three-dimensional porous carbon.

9. A negative electrode current collector with a carbon-containing functional layer according to claim 1, characterized in that: The substrate is copper foil with a thickness of 10-20 μm; the areal density of the carbon-containing functional layer is 1.0-1.5 mg / cm³. 2 .

10. The method for preparing a negative electrode current collector with a carbon functional layer according to claim 1, characterized in that: Includes the following steps: Step 1: Add the carbon skeleton, sodium-loving material, binder, and surfactant to the solvent in sequence, and stir evenly to obtain a carbon-containing functional slurry; Step 2: Coat the carbon-containing functional slurry onto the substrate, dry it to form a carbon-containing functional layer; roll press to obtain the negative electrode current collector.

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