CN-116278232-B - Aluminum foil for negative current collector of sodium ion battery

Abstract

The invention discloses an aluminum foil for a negative electrode current collector of a sodium ion battery, which is prepared by laminating a coating binder of a pretreated aluminum foil, wherein the pretreated aluminum foil comprises the following raw materials, by weight, 0.15-0.18% of Cu, 0.50-0.70% of Fe, 0.20-0.30% of Si, less than or equal to 0.01% of Mn, less than or equal to 0.01% of Mg, less than or equal to T i%, less than or equal to 0.03% of A l and other unavoidable impurity elements. The method has the advantages that the types and the contents of the components are limited, and the intermediate annealing is performed after rough rolling is finished, so that the internal stress defect generated by rolling is eliminated, and the uniformity of the alloy structure is effectively improved. After cast rolling, intermediate annealing and cold rolling, the dislocation density of the aluminum foil can be improved by matching with the subsequent pass rolling, so that the problem that the aluminum foil of the lithium battery is easy to break and difficult to process is solved.

Inventors

• CUI GUANGJIAN
• DING XIAOLI
• ZHANG SHANGLING
• WANG JIAPENG

Assignees

• 江苏中基新能源科技集团有限公司

Dates

Publication Date

20260505

Application Date

20220909

Claims (1)

1. 1. The aluminum foil for the negative electrode current collector of the sodium ion battery is characterized by comprising the following steps of: Step S1, soaking a pretreated aluminum foil in a sodium hydroxide solution at a temperature of 20-25 ℃ for 2-4 hours, and drying for later use; Step S2, uniformly mixing KH560, ethanol and deionized water, soaking pretreated aluminum foil in the mixture for 3-5 hours, and drying the mixture for later use; Step S3, coating adhesive on one surface of the pretreated aluminum foil, bonding one surfaces of the two pretreated aluminum foils coated with the adhesive, and pressing the two surfaces to prepare the aluminum foil for the negative electrode current collector of the sodium ion battery under the condition that the temperature is 70-80 ℃; The pretreated aluminum foil comprises the following raw materials, by weight, 0.15-0.18% of Cu, 0.50-0.70% of Fe, 0.20-0.30% of Si, less than or equal to 0.01% of Mn, less than or equal to 0.01% of Mg, less than or equal to 0.03% of Ti, and the balance of Al and other unavoidable impurity elements; The pretreatment aluminum foil is prepared by the following steps: step A1, heating, smelting and uniformly stirring the raw materials at the temperature of 730-740 ℃ to obtain a mixture A2, casting and rolling the mixture to obtain an aluminum product; Step A3, cold rolling the aluminum material to a thickness of 0.4-0.6mm, treating for 27-35h at the temperature of 240-270 ℃, and then rolling to a thickness of 0.2-0.3mm, and then trimming; A4, rolling for multiple times to 0.013mm to obtain a pretreated aluminum foil; The specific smelting step in the step A1 is to add a refining agent at the temperature of 730 ℃ for 20min, heat up to 740 ℃ and continue refining for 20min, adjust the components and guide the furnace, and the furnace guide temperature is 750 ℃; The refining agent is a chloride refining agent, and the chloride refining agent comprises aluminum chloride, zinc chloride, ferric chloride and manganese chloride; The temperature of the casting and rolling front box in the step A2 is 694-704 ℃, the casting and rolling speed is 850-1000mm/min, the casting and rolling area is 55-75mm, the roll surface temperature is less than or equal to 75 ℃, and the thickness of the cast and rolled aluminum material is 7.0-8.0mm; the multiple-pass rolling in the step A4 is divided into a front pass and a rear pass, wherein the roughness of the front pass working roll is 0.25 mu m, the convexity is 50%, the roughness of the rear pass working roll is 0.12 mu m, and the convexity is 90%; The adhesive is prepared by the following steps: Step B1, mixing and stirring sodium dodecyl benzene sulfonate, D4, KH570 and deionized water to obtain seed liquid, and mixing and reacting the seed liquid, D4, KH570 and hexamethyldisiloxane to obtain polysiloxane core emulsion; step B2, mixing acrylic acid, epoxypropanol, concentrated sulfuric acid and deionized water for reflux reaction to prepare an intermediate 1, mixing and reacting the intermediate 1, polysiloxane core emulsion, 1, 4-butanediol diacrylate, allyl methacrylate, potassium persulfate and deionized water, and adjusting the pH value of a reaction solution to be alkaline to prepare a binder; The dosage ratio of the sodium dodecyl benzene sulfonate, the D4, the KH570 and the deionized water in the step B1 is 2g to 0.01mol to 50mL, and the dosage ratio of the seed solution, the D4, the KH570 and the hexamethyldisiloxane is 50mL to 0.01mol to 0.05mol to 0.02mol; The dosage ratio of the acrylic acid to the epoxypropanol to the concentrated sulfuric acid in the step B2 is 0.01mol:0.01mol:20mL, the mass fraction of the concentrated sulfuric acid is 98%, the dosage ratio of the intermediate 1 to the polysiloxane core emulsion to the 1, 4-butanediol diacrylate to the allyl methacrylate to the deionized water is 0.02mol:50mL:0.03mol:0.05mol:20mL, and the dosage of the potassium persulfate is 0.3-0.4% of the mass of the reactant.

Description

Aluminum foil for negative current collector of sodium ion battery Technical Field The invention relates to the technical field of battery preparation, in particular to an aluminum foil for a negative electrode current collector of a sodium ion battery. Background The rapid development of the power lithium battery industry brings about further development of the aluminum foil industry for the power lithium battery. The power lithium battery has the advantages of high energy density, high working electricity, light weight, small volume, small self-discharge, no memory effect, multiple cycle times and the like, and is gradually replacing the traditional lead-acid storage battery. The lithium ion battery has the advantages of high working voltage platform, good multiplying power performance, long service life, high energy storage density, low self-discharge rate and the like, so that the lithium ion battery becomes an ideal energy storage device, but the lithium ion battery has unavoidable problems of lithium resource shortage, uneven distribution, high cost and the like, and has certain potential safety hazard. Compared with lithium, the sodium element of the same main group has similar physical and chemical properties as lithium, and has the advantages of being rich in resources by thousands of times than lithium in crust, being rich in resources, low in cost and the like compared with a lithium ion battery, so that the sodium ion battery is generated, and becomes an excellent choice for replacing the lithium ion battery, however, when sodium is used as a sodium ion negative electrode material, although the energy density of sodium ions can be improved, the defects of sodium dendrite growth, volume expansion, low cycle efficiency and the like of the sodium ion battery in the repeated cycle process are caused. Unlike lithium which is easy to perform alloying reaction with an aluminum-based current collector at a low potential of a negative electrode, sodium negative electrode does not perform alloying reaction with an aluminum-based current collector, and is commonly used as a negative current collector of a sodium ion battery, and by reducing the local current density of the aluminum-based current collector of the negative electrode of the sodium ion battery, the growth and volume expansion of sodium dendrite can be inhibited. In combination with the above market demands, there is currently an increasing demand for aluminum foil for lithium batteries. The aluminum foil for lithium batteries is used as a current collector of lithium batteries, and during a roll-calendering and isopiestic process of an electrode coated with an active material such as graphite, the aluminum foil for lithium batteries needs to be deformed enough to adapt to the surface characteristics of the active material so as to prevent deterioration of the contact performance between the aluminum foil and the active material. If the electrode coated with the active material has a low tensile strength, the electrode is liable to break during the flattening process such as rolling. Meanwhile, the elongation rate must be enough, if the elongation rate is low, when the electrode coated with active substances is subjected to flattening procedures such as rolling and the like, the aluminum foil for the power functional material generates internal stress to split, the battery capacity, the cycle life and other performances are directly influenced, and in order to meet the requirements of the battery performance in the current market, the pure aluminum foil for the commonly used lithium battery is provided with 1060, 1050 and other alloys, but the alloy has the quality problems such as soft strength, low elongation rate, uneven surface roughness, insufficient surface quality cleanliness and the like, which are to be solved. Disclosure of Invention The invention aims to provide an aluminum foil for a negative electrode current collector of a sodium ion battery, which solves the problems of soft strength, low elongation and uneven surface roughness of the aluminum foil at the present stage. The aim of the invention can be achieved by the following technical scheme: An aluminum foil for a negative electrode current collector of a sodium ion battery is prepared by the following steps: Step S1, soaking a pretreated aluminum foil in a sodium hydroxide solution at a temperature of 20-25 ℃ for 2-4 hours, and drying for later use; Step S2, uniformly mixing KH560, ethanol and deionized water, soaking pretreated aluminum foil in the mixture for 3-5 hours, and drying the mixture for later use; And S3, coating adhesive on one surface of the pretreated aluminum foil, bonding one surfaces of the two pretreated aluminum foils coated with the adhesive, and pressing the two surfaces at the temperature of 70-80 ℃ to obtain the aluminum foil for the negative electrode current collector of the sodium ion battery. Further, the mass fraction of the sodium hydroxide solut