CN-121983584-A - Composite current collector base film, preparation method thereof, composite current collector, electrode plate and electrochemical device

CN121983584ACN 121983584 ACN121983584 ACN 121983584ACN-121983584-A

Abstract

The invention provides a composite current collector base film, a preparation method thereof, a composite current collector, an electrode plate and an electrochemical device, relates to the technical field of composite current collector preparation, and is particularly suitable for the technical field of battery preparation. The composite current collector base film comprises an insulating layer and a gradient strengthening structure arranged on at least one surface of the insulating layer, wherein the gradient strengthening structure sequentially comprises an organic hardening layer, a hybridization hardening layer and an inorganic hardening layer from the surface of the insulating layer to the outside, and Young modulus and hardness of the organic hardening layer, the hybridization hardening layer and the inorganic hardening layer sequentially increase. According to the invention, the reinforced functional layer with the design modulus and the hardness gradually increasing from inside to outside is laminated on the surface of the insulating layer to form the interface transition region with smaller connection difference, and the surface hardness and the overall rigidity of the composite current collector base film are effectively enhanced, so that the prepared composite current collector is provided.

Inventors

WU YANG
SHI YAMIN
WANG YINGMIN
BU SHAONING
WU JUNWEI
WENG WEIJIA

Assignees

江苏英联复合集流体有限公司

Dates

Publication Date: 20260505
Application Date: 20260228

Claims (12)

1. The composite current collector base film is characterized by comprising an insulating layer and a gradient strengthening structure arranged on at least one surface of the insulating layer, wherein the gradient strengthening structure sequentially comprises an organic hardening layer, a hybridization hardening layer and an inorganic hardening layer from the surface of the insulating layer to the outside; Wherein young's modulus and hardness of the organic hardening layer, the hybrid hardening layer and the inorganic hardening layer are sequentially increased.
2. The composite current collector substrate film of claim 1, wherein the composite current collector substrate film satisfies at least one of the following conditions: (1) The thickness of the insulating layer is 4-8 mu m; (2) The insulating layer is made of one or more of polyimide, polyethylene, polypropylene and polyethylene terephthalate; (3) The Young modulus of the insulating layer is 2Gpa-8GPa, and the hardness is 10 HV-40 HV; (4) The thickness of the organic hardening layer is 100nm-1000nm; (5) The Young modulus of the organic hardening layer is 5GPa-10GPa, and the hardness is 80HV-150 HV; (6) The thickness of the hybridization hardening layer is 100nm-1000nm; (7) The Young modulus of the hybrid hardening layer is 10GPa-50GPa, and the hardness is 200HV-300 HV; (8) The thickness of the inorganic hardening layer is 10nm-100nm; (9) The Young's modulus of the inorganic hardening layer is 200GPa-300 GPa, and the hardness is 1000HV-1500 HV.
3. The method for producing a composite current collector base film according to claim 1 or 2, comprising laminating an organic cured layer, a hybrid cured layer and an inorganic cured layer in this order on at least one surface of the insulating layer.
4. The method of claim 3, further comprising activating the surface of the insulating layer before preparing the organic hardened layer on the insulating layer; the activation treatment step satisfies at least one of the following conditions: (1) The activation treatment includes one or more of corona treatment and plasma treatment; (2) The power of the corona treatment is 10-50W min/m 2 , and the surface tension of the insulating layer after the treatment is 45 dyn/cm-50 dyn/cm; (3) The gas used in the plasma treatment is a mixed gas of oxygen and argon, the vacuum degree is 0.01-0.1 Pa, and the radio frequency power is 0.1-10 kW; Preferably, the flow ratio of the oxygen to the argon is 1 (1-2).
5. The method according to claim 3, wherein the organic hardened layer is obtained by coating a first coating liquid on the insulating layer and curing; The first coating liquid comprises, by weight, 30% -50% of a high-functionality prepolymer, 20% -40% of a reactive diluent, 3% -5% of an interface coupling agent, 2% -4% of a photoinitiator, 0.1% -2% of a functional auxiliary agent and the balance of a solvent.
6. The method according to claim 5, wherein the hybrid hardened layer is produced by coating a second coating liquid on the organic hardened layer and curing; The second coating liquid comprises, by weight, 20% -40% of a high-functionality prepolymer, 20% -35% of a functionalized sol, 10% -25% of a reactive diluent, 3% -5% of an interface coupling agent, 2% -4% of a photoinitiator, 0.1% -2% of a functional auxiliary agent, and the balance of a solvent; preferably, the functionalized sol comprises a silica sol; preferably, the particle size of the functionalized sol is 5nm-50nm.
7. The method of producing according to claim 6, wherein the first coating liquid and the second coating liquid satisfy at least one of the following conditions: (1) The high-functionality prepolymer in the first coating liquid and the second coating liquid is respectively and independently selected from one or more of epoxy acrylate, polyurethane acrylate, polyester acrylate, amino acrylate and unsaturated polyester; (2) The reactive diluents in the first coating liquid and the second coating liquid are respectively and independently selected from one or more of tetrapropylene glycol diacrylate, 1, 6-hexanediol diacrylate, tripropylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, ethylene glycol diglycidyl ether diacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate and trimethylolpropane triacrylate; (3) The interface coupling agents in the first coating liquid and the second coating liquid are respectively and independently selected from one or more of gamma-methacryloxypropyl trimethoxysilane, gamma-aminopropyl triethoxysilane, gamma-glycidol ether oxypropyl trimethoxysilane and gamma-mercaptopropyl trimethoxysilane; (4) The photoinitiator in the first coating liquid and the photoinitiator in the second coating liquid are respectively and independently selected from one or more of 2,4, 6-trimethyl benzoyl diphenyl phosphine oxide, 1-hydroxy-cyclohexyl phenyl ketone, benzoin dimethyl ether, isopropyl thioxanthone, 4-methylbenzophenone, 4-phenylbenzophenone and benzyl dimethyl amino ethyl ester; (5) The functional auxiliary agents in the first coating liquid and the second coating liquid are respectively and independently selected from one or more of a leveling agent and an antioxidant; Preferably, the leveling agent comprises one or more of fluorocarbon leveling agents, organic silicon leveling agents, acrylic leveling agents and cellulose acetate leveling agents; preferably, the antioxidant comprises one or more of butylated hydroxytoluene, butylated hydroxyanisole, ethylenediamine tetraacetic acid and tert-butylhydroquinone; (6) The solvent in the first coating liquid and the second coating liquid is selected from one or more of ethyl acetate, isopropanol, methanol, ethanol, isopropanol, tertiary butanol, H 2 O, n-propyl acetate, n-butyl acetate, acetone, butanone and methyl isobutyl ketone.
8. The method according to claim 5 or 6, wherein the curing is a gradient curing comprising sequentially performing infrared drying, hot air drying, and ultraviolet irradiation; Preferably, the temperature of the infrared drying is 40 ℃ to 70 ℃; preferably, the temperature of the hot air drying is 60 ℃ to 100 ℃; Preferably, the energy of the ultraviolet irradiation is 300mj/cm 2 -1000mj/cm 2 .
9. The method according to claim 3, wherein the inorganic hardened layer is formed on the surface of the hybrid hardened layer by vacuum evaporation coating or magnetron sputtering coating; Preferably, when vacuum evaporation coating is adopted, the vacuum degree of the plating is 1X 10 -2 Pa-4×10 -2 Pa, the oxygen gas inlet amount is 1000sccm-3000 sccm, the argon gas inlet amount is 500sccm-1000 sccm, the winding speed is 200m/min-800 m/min, the wire feeding speed is 100m/min-200 m/min, the winding tension is 150N-200N, the unwinding tension is 210N-230N, the ion source voltage is 1000V-2000V, and the temperature of the cold roller is 0-20 ℃.
10. The composite current collector is characterized by comprising a composite current collector base film and a metal layer positioned on at least one side of the composite current collector base film, wherein the composite current collector base film is the composite current collector base film according to claim 1 or 2 or prepared by the preparation method according to any one of claims 3-9.
11. An electrode sheet comprising the composite current collector of claim 10.
12. An electrochemical device comprising the electrode sheet according to claim 11.

Description

Composite current collector base film, preparation method thereof, composite current collector, electrode plate and electrochemical device Technical Field The invention relates to the technical field of preparation of composite current collectors, in particular to a composite current collector base film, a preparation method thereof, a composite current collector, an electrode plate and an electrochemical device. Background The current collector is used as a very important component of the battery and is used for collecting the current generated by the active substances of the battery so as to form larger current to be output outwards, and the cycle life, the energy density, the safety and the like of the battery can be directly influenced by the performance of the current collector. At present, aluminum foil and copper foil are used as current collectors for positive and negative plates in lithium batteries and sodium batteries, and the current collectors are unfavorable for controlling the cost of the batteries and improving the energy density. The composite current collector has significant advantages over conventional foil current collectors. The composite current collector is generally of a sandwich structure, the inner layer is a high-molecular insulating layer, and the two sides are metal conducting layers. Because the metal layer on the surface of the composite current collector is thinner, the internal polymer layer is lighter, so that the overall weight of the current collector can be well lightened, and the energy density of the lithium ion battery is further increased. However, the existing composite current collector has great interface property difference with the metal coating due to great difference between the rigidity, surface hardness and other material properties of the polymer insulating layer and the metal coating, and the metal layer is easy to separate after being rolled by high compaction density. Particularly, for the composite aluminum foil current collector, the overall rigidity is low, so that the pressure resistance is poor, and the cracking and damage phenomena of the high polymer insulating layer are more easily formed after the composite aluminum foil current collector is deformed for a plurality of times under the pressure system with the requirement of high compaction density of the positive electrode active material. In addition, lithium ion battery is easy to take place internal short circuit when receiving extrusion, collision or abnormal conditions such as puncture, causes the battery to fire and even explode, though current composite current collector is owing to being provided with the polymer insulating layer wherein, can play certain separation electron transmission's effect when the puncture, but the hardness of polymer insulating layer material is generally lower, when taking place the drift bolt or inside to puncture, can't make the metal layer directly take place to fracture, break so as to form the circuit break, the metal layer still remains certain conductivity, battery temperature still is the rising trend, there is the thermal runaway risk, short circuit current is easy to be conducted to the regional nearby wide range of acupuncture at this moment, enlarge the short circuit region, reduced the passing rate of acupuncture experiment and the safety in utilization of battery. Disclosure of Invention The invention aims to provide a composite current collector base film, which at least solves one of the technical problems in the prior art. The second purpose of the invention is to provide a preparation method of the composite current collector base film. The invention further aims to provide a composite current collector. The fourth object of the present invention is to provide an electrode sheet. The fifth object of the present invention is to provide an electrochemical device. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: The invention provides a composite current collector base film, which comprises an insulating layer and a gradient strengthening structure arranged on at least one surface of the insulating layer, wherein the gradient strengthening structure sequentially comprises an organic hardening layer, a hybridization hardening layer and an inorganic hardening layer from the surface of the insulating layer to the outside; Wherein young's modulus and hardness of the organic hardening layer, the hybrid hardening layer and the inorganic hardening layer are sequentially increased. Further, the composite current collector base film satisfies at least one of the following conditions: (1) The thickness of the insulating layer is 4-8 mu m; (2) The insulating layer is made of one or more of polyimide, polyethylene, polypropylene and polyethylene terephthalate; (3) The Young modulus of the insulating layer is 2Gpa-8Gpa, and the hardness is 10 HV-40 HV; (4) The thickness of the organic