CN112366323A - Composite foil for improving safety of lithium ion battery, and preparation method and application thereof - Google Patents
Composite foil for improving safety of lithium ion battery, and preparation method and application thereof Download PDFInfo
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- CN112366323A CN112366323A CN202011194224.2A CN202011194224A CN112366323A CN 112366323 A CN112366323 A CN 112366323A CN 202011194224 A CN202011194224 A CN 202011194224A CN 112366323 A CN112366323 A CN 112366323A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0421—Methods of deposition of the material involving vapour deposition
- H01M4/0423—Physical vapour deposition
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/669—Steels
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a composite foil for improving the safety of a lithium ion battery, a preparation method and application thereof. The preparation method comprises the following steps: and coating a polymer solution on the surface of the substrate layer, drying to form a polymer layer, and depositing on the surface of the polymer layer to form an aluminum foil layer to obtain the composite foil. The composite foil provided by the invention is mainly used for improving the safety of the battery, the copper foil and the aluminum foil which are commonly used by the lithium ion battery are replaced by stainless steel foil, the production cost is reduced, and meanwhile, the safety of a battery cell is further improved by redesigning the foil.
Description
Technical Field
The invention belongs to the technical field of lithium ions, and relates to a composite foil for improving the safety of a lithium ion battery, and a preparation method and application thereof.
Background
The lithium ion secondary battery has the advantages of high energy density, high power density, long endurance time and the like, is widely used for the power battery for the vehicle, and has more and more outstanding safety along with the large-scale application of the battery. Safety remains a critical factor that limits the application of lithium ion batteries in high energy/high power applications. The potential safety problem of the lithium ion battery greatly influences the popularization of new energy vehicles.
Lithium ion batteries have been widely applied to various industries, and along with the higher requirements of popularization and use experience in the application field, the requirements of terminal customers on the safety performance of lithium batteries are also higher, and products which can completely and maturely improve the safety performance of lithium ion batteries and the like are not available in the current industry. Although the specific explosion reasons of the once-occurred mobile phone explosion events are not clearly examined, the analysis in the industry is probably caused by that the safety coefficient of the high-energy-density lithium battery used by the mobile phone explosion events does not meet the requirements of related international certification.
Lithium ion batteries have been rapidly developed in recent years because of their advantages such as high specific energy and no memory effect. Particularly, with the gradual application of lithium ion batteries in the fields of EV pure electric vehicles, low-speed electric vehicles, and the like, the safety performance and cycle performance of lithium ion batteries have been receiving attention all the time. Therefore, thermal runaway management and control of power lithium ion batteries under abusive conditions has been a major concern of research and concern in the industry. The liquid lithium ion battery adopts organic carbonate liquid electrolyte, is easy to leak, burn and explode, has low safety, cannot be needled, and is easy to ignite and explode after needling.
Generally, the process of thermal runaway of the lithium ion battery is as follows: when a short circuit occurs in an electric core, a large current of the instant short circuit generates heat through a cathode and an anode, firstly, the SEI starts to self-decompose and release heat when reaching a certain temperature condition, along with the accumulation of the heat, the graphite anode with the electric state reacts with electrolyte to release heat, and meanwhile, the heat is accumulated to enable the temperature of the electric core to rise, when the temperature of the electric core rises to a certain degree, the cathode structure in the charging state collapses, and simultaneously releases free high-reaction active oxygen atoms, the released oxygen atoms react with a binder in an electrode material, a conductive agent auxiliary material, electrolyte in the electric core and the like, a large amount of heat is released instantly, and the battery burns or explodes.
At present, the following safety protection means for preventing the battery core from thermal runaway in the lithium ion battery are mainly used: (1) the current circulation is organized through the shutdown function of the diaphragm, the risk of thermal runaway is reduced, the main defect of the method is that after the diaphragm is shut down, the battery core is scrapped and can not be used any more, and because the diaphragm used by the conventional lithium ion battery is a porous polyolefin film, the shutdown mechanism is mainly that polyethylene is melted at 130 ℃ to shut down the current, and the temperature distribution inside the lithium ion battery is usually uneven when short circuit occurs, so that the situation that part of the battery core reaches the shutdown temperature and part of the battery core cannot reach the shutdown temperature occurs, and the current of the whole battery core cannot be cut off; (2) and the cell CID is broken to play a role in protecting the cell when the gas pressure generated by the cell due to violent reaction or other forms of reaction reaches the CID breaking threshold value. The protection in this form is similar to the diaphragm shut-off, and after the protection effect occurs, the cell cannot be used any longer, and is unrecoverable protection.
CN106848383A discloses a lithium ion battery, including negative plate and positive plate, the coating has the organic polymer coating of chemical inertness on the negative plate, the organic polymer coating is insoluble in water, the melting point of organic polymer coating is 90 ~ 110 ℃, the organic polymer coating melts and forms the coating on the negative plate surface when lithium ion battery takes place thermal runaway, isolated the contact short circuit of positive plate and negative plate.
CN104347892A discloses a high lithium cell of security, under the condition that does not influence the chemical property of single packet of lithium cell piece, can be fine solve the outside acupuncture of lithium cell or the inside short circuit of lithium cell and reduce the inside heat of lithium cell and the high lithium cell of security of the safety problem of battery deformation. The lithium battery comprises a lithium battery body, wherein the lithium battery body comprises a plurality of single-pack lithium battery pieces which are sequentially connected in series, and circuit breakers are respectively connected in series on connecting lines of two adjacent layers of single-pack lithium battery pieces; the outer side surface of the single-pack lithium battery piece is wrapped with a heat insulation sealing cloth layer, the outer surface of the heat insulation sealing cloth layer is wrapped with a first protection mesh layer, and main body glue is sealed in each mesh of the first protection mesh layer; the outer surface of the first protection net sheet layer is wrapped with a second protection net sheet layer, and auxiliary glue is sealed in each net hole of the second protection net sheet layer.
CN106299204A discloses a high security lithium battery diaphragm, high security lithium battery diaphragm includes the base film and coats the cladding alumina coating of base film single face or two-sided, cladding alumina coating thickness is 1 ~ 4 mu m.
Aiming at the safety problem of lithium batteries, most of the existing battery core manufacturers adopt a diaphragm to coat a ceramic layer, add metal materials such as nickel, manganese and the like to the anode for doping, perform coating processing on the surface of copper foil/aluminum foil, and use graphene, lithium titanate and other modes to improve the safety. The above measures have the characteristics and also play a certain role in improving safety. However, the safety performance of the battery still cannot meet the requirement, and therefore, a lithium ion battery with high safety performance is urgently needed.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the composite foil for improving the safety of the lithium ion battery, the preparation method and the application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a composite foil for improving the safety of a lithium ion battery, wherein the composite foil comprises a substrate layer, a polymer layer and an aluminum foil layer which are sequentially stacked.
The composite foil provided by the invention is mainly used for improving the safety of a battery, and after the composite foil is used for a lithium ion battery through redesigning the foil, when the lithium ion battery is needled, firstly, the current of an aluminum foil layer is overlarge, and the aluminum foil layer is fused, so that a first layer of safety net is provided; because the diameter of needle is greater than the aperture of polymer layer, when the needle penetrated the aluminium foil layer and pierces the polymer layer, the polymer can wrap up the syringe needle, increases insulating, and the stainless steel layer is hugged closely to the polymer layer simultaneously, can reduce the piece, prevents the short circuit, reduces short circuit current, has greatly improved the anti-needling ability security of battery.
As a preferable technical solution of the present invention, the substrate layer is a stainless steel layer.
According to the invention, the copper foil and the aluminum foil which are commonly used as the substrate layer are replaced by the stainless steel foil, so that the production cost is reduced.
Preferably, the polymer layer comprises a polymer.
Preferably, the polymer comprises one or a combination of at least two of polyethylene glycol acrylate, polydivinyl sulfide, polyvinylidene fluoride, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polymethyl methacrylate, polytetrafluoroethylene, polypropylene carbonate, polyethylene carbonate or polyvinyl acetate.
In a preferred embodiment of the present invention, the polymer layer has a pore diameter of 0.3 to 0.8mm, for example, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm or 0.8mm, but the pore diameter is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable.
Preferably, the polymer layer has a thickness of 3 to 5 μm, and may be, for example, 3.0 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, 4.0 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, or 5.0 μm, but is not limited to the values listed, and other values not listed within the range of values are also applicable.
Preferably, the aluminum foil layer has a thickness of 1 to 2 μm, and may be, for example, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm or 2.0 μm, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
In a second aspect, the present invention provides a method for preparing the composite foil of the first aspect, wherein the method comprises:
and coating a polymer solution on the surface of the substrate layer, drying to form a polymer layer, and depositing on the surface of the polymer layer to form an aluminum foil layer to obtain the composite foil. .
As a preferable technical scheme of the invention, the polymer solution is prepared by adopting the following method:
adding a polymer into an organic solvent in an environment with the dew point less than or equal to-40 ℃, and mixing to obtain the polymer solution.
Preferably, the polymer comprises one or a combination of at least two of polyethylene glycol acrylate, polydivinyl sulfide, polyvinylidene fluoride, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polymethyl methacrylate, polytetrafluoroethylene, polypropylene carbonate, polyethylene carbonate or polyvinyl acetate.
Preferably, the organic solvent comprises one or a combination of at least two of dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, acetonitrile or N-methylpyrrolidone.
Preferably, the polymer is 30 to 50 wt% of the polymer solution, for example, 30 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, 40 wt%, 42 wt%, 44 wt%, 46 wt%, 48 wt% or 50 wt%, but not limited to the recited values, and other values not recited in the range of the recited values are also applicable.
In a preferred embodiment of the present invention, the drying temperature is 80 to 90 ℃, and may be, for example, 80 ℃, 81 ℃, 82 ℃, 83 ℃, 84 ℃, 85 ℃, 86 ℃, 87 ℃, 88 ℃, 89 ℃ or 90 ℃, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
Preferably, the drying time is 20 to 30 hours, for example, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours or 30 hours, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
In a preferred embodiment of the present invention, the deposition method is evaporation.
Preferably, the evaporation process comprises: and in a vacuum environment, heating and melting the solid aluminum until the solid aluminum is evaporated to form gaseous aluminum, depositing the gaseous aluminum on the surface of the polymer layer, and cooling and reducing to obtain the aluminum foil layer.
Preferably, the degree of vacuum is 1.3X 10-2～1.3×10-3Pa may be, for example, 0.0013Pa, 0.002Pa, 0.003Pa, 0.004Pa, 0.005Pa, 0.006Pa, 0.007Pa, 0.008Pa, 0.009Pa, 0.01Pa, 0.012Pa or 0.013Pa, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.
Preferably, the solid aluminum is heated to 1200-1400 ℃, for example 1200 ℃, 1220 ℃, 1240 ℃, 1260 ℃, 1280 ℃, 1300 ℃, 1320 ℃, 1340 ℃, 1360 ℃, 1380 ℃ or 1400 ℃, but not limited to the values listed, and other values not listed within this range are equally applicable.
Preferably, the cooling temperature is-18 to-15 ℃, and may be, for example, -18 ℃, -17.5 ℃, -17 ℃, -16.5 ℃, -16 ℃, -15.5 ℃ or-15 ℃, but is not limited to the values recited, and other values not recited in the range of values are equally applicable.
In a third aspect, the invention provides an electrode sheet, which comprises the composite foil of the first aspect, and a positive electrode material layer or a negative electrode material layer arranged on the surface of the composite foil.
In a fourth aspect, the present invention provides a method for preparing the electrode sheet of the third aspect, wherein the method for preparing the electrode sheet comprises:
coating positive slurry or negative slurry on the surface of the composite foil material, and then sequentially drying, rolling and slicing to obtain the electrode slice.
In a fifth aspect, the invention provides a lithium ion battery, wherein the electrode sheet of the third aspect is used as an electrode.
Compared with the prior art, the invention has the beneficial effects that:
the composite foil provided by the invention is mainly used for improving the safety of the battery, the copper foil and the aluminum foil which are usually used by the lithium ion battery are replaced by stainless steel foil, the production cost is reduced, and meanwhile, through redesigning the foil, after the composite foil is used for the lithium ion battery, when the lithium ion battery is needled, the current of the aluminum foil layer is overlarge, the aluminum foil layer is fused, and a first layer of safety net is provided; because the diameter of needle is greater than the aperture of polymer layer, when the needle penetrated the aluminium foil layer and pierces the polymer layer, the polymer can wrap up the syringe needle, increases insulating, and the stainless steel layer is hugged closely to the polymer layer simultaneously, can reduce the piece, prevents the short circuit, reduces short circuit current, has greatly improved the anti-needling ability security of battery.
Drawings
Fig. 1 is a schematic structural diagram of a composite foil provided in embodiment 1 of the present invention.
Wherein, 1-aluminum foil layer; 2-a polymer layer; 3-stainless steel layer.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Example 1
The embodiment provides a preparation method of a composite foil, which comprises the following steps:
(1) adding polymer polyethylene glycol polyacrylate into an organic solvent dimethylacetamide under the environment of a dew point of less than or equal to-40 ℃, and mixing under an ultrasonic condition to obtain a polymer solution with the concentration of 30 wt%;
(2) coating a polymer solution on the surface of the stainless steel layer 1, wherein the coating thickness is 3 mu m, and after drying for 30h at 80 ℃, a polymer layer 2 is formed, and the average pore diameter of the polymer layer 2 is 0.3 mm;
(3) heating and melting solid aluminum at 1200 ℃ in a vacuum environment of 0.0013Pa until the solid aluminum is evaporated to form gaseous aluminum, depositing the gaseous aluminum on the surface of the polymer layer 2, cooling and reducing at-15 ℃ to form an aluminum foil layer 1 with the diameter of 1 mu m, and finally obtaining the composite foil shown in the figure 1.
Example 2
The embodiment provides a preparation method of a composite foil, which comprises the following steps:
(1) adding polymer polydivinyl sulfide into organic solvent dimethyl sulfoxide in an environment with the dew point less than or equal to-40 ℃, and mixing under an ultrasonic condition to obtain a polymer solution with the concentration of 34 wt%;
(2) coating a polymer solution on the surface of the stainless steel layer 1, wherein the coating thickness is 3.4 mu m, and after drying for 28 hours at 82 ℃, a polymer layer 2 is formed, and the average pore diameter of the polymer layer 2 is 0.35 mm;
(3) and in a vacuum environment of 0.003Pa, heating and melting solid aluminum at 1240 ℃ until the solid aluminum is evaporated to form gaseous aluminum, depositing the gaseous aluminum on the surface of the polymer layer 2, cooling and reducing at-15.6 ℃ to form an aluminum foil layer 1 with the thickness of 1.2 mu m, and finally obtaining the composite foil.
Example 3
The embodiment provides a preparation method of a composite foil, which comprises the following steps:
(1) adding polymer polyvinylidene fluoride into an organic solvent N-methyl pyrrolidone in an environment with the dew point of less than or equal to-40 ℃, and mixing under an ultrasonic condition to obtain a polymer solution with the concentration of 38 wt%;
(2) coating the surface of the stainless steel layer 1 with a polymer solution, wherein the coating thickness is 3.8 mu m, and after drying for 26 hours at 84 ℃, a polymer layer 2 is formed, and the average pore diameter of the polymer layer 2 is 0.56 mm;
(3) and heating and melting solid aluminum at 1280 ℃ in a vacuum environment of 0.006Pa to evaporate to form gaseous aluminum, depositing the gaseous aluminum on the surface of the polymer layer 2, cooling and reducing at-16.2 ℃ to form an aluminum foil layer 1 with the diameter of 1.4 mu m, and finally obtaining the composite foil.
Example 4
The embodiment provides a preparation method of a composite foil, which comprises the following steps:
(1) adding polymer polymethyl methacrylate into organic solvent tetrahydrofuran in an environment with the dew point less than or equal to-40 ℃, and mixing under an ultrasonic condition to obtain a polymer solution with the concentration of 42 wt%;
(2) coating a polymer solution on the surface of the stainless steel layer 1, wherein the coating thickness is 4.2 mu m, and the polymer layer 2 is formed after drying for 24 hours at 86 ℃, and the average pore diameter of the polymer layer 2 is 0.67 mm;
(3) and in a vacuum environment of 0.008Pa, heating and melting solid aluminum at 1320 ℃ until the solid aluminum is evaporated to form gaseous aluminum, depositing the gaseous aluminum on the surface of the polymer layer 2, cooling and reducing at-16.8 ℃ to form an aluminum foil layer 1 with the diameter of 1.6 mu m, and finally obtaining the composite foil.
Example 5
The embodiment provides a preparation method of a composite foil, which comprises the following steps:
(1) adding polymer polyvinyl acetate into an organic solvent acetonitrile in an environment with the dew point less than or equal to-40 ℃, and mixing under an ultrasonic condition to obtain a polymer solution with the concentration of 46 wt%;
(2) coating the surface of the stainless steel layer 1 with a polymer solution, wherein the coating thickness is 4.6 mu m, and the polymer layer 2 is formed after drying at 88 ℃ for 22h, and the average pore diameter of the polymer layer 2 is 0.74 mm;
(3) and heating and melting solid aluminum at 1360 ℃ in a vacuum environment of 0.01Pa until the solid aluminum is evaporated to form gaseous aluminum, depositing the gaseous aluminum on the surface of the polymer layer 2, cooling and reducing at-17.4 ℃ to form an aluminum foil layer 1 with the diameter of 1.8 mu m, and finally obtaining the composite foil.
Example 6
The embodiment provides a preparation method of a composite foil, which comprises the following steps:
(1) adding polymer polytetrafluoroethylene into an organic solvent N-methyl pyrrolidone in an environment with a dew point of less than or equal to-40 ℃, and mixing under an ultrasonic condition to obtain a polymer solution with the concentration of 50 wt%;
(2) coating a polymer solution on the surface of the stainless steel layer 1, wherein the coating thickness is 5 mu m, and after drying for 20 hours at 90 ℃, a polymer layer 2 is formed, and the average pore diameter of the polymer layer 2 is 0.8 mm;
(3) heating and melting solid aluminum at 1400 ℃ in a vacuum environment of 0.013Pa until the solid aluminum is evaporated to form gaseous aluminum, depositing the gaseous aluminum on the surface of the polymer layer 2, cooling and reducing at-18 ℃ to form an aluminum foil layer 1 with the diameter of 2 mu m, and finally obtaining the composite foil.
Comparative example 1
The comparative example provides a method for preparing a composite foil, the method comprising the steps of:
heating and melting solid aluminum at 1200 ℃ in a vacuum environment of 0.0013Pa until the solid aluminum is evaporated to form gaseous aluminum, depositing the gaseous aluminum on the surface of the stainless steel layer 1, cooling and reducing at-15 ℃ to form an aluminum foil layer 1 with the diameter of 1 mu m, and finally obtaining the composite foil.
The composite foil prepared by the comparative example only comprises a stainless steel layer 1 and an aluminum foil layer 1, and compared with the example 1, the intermediate polymer layer 2 is lacked, and the operation steps and the process conditions adopted in the deposition process of the aluminum foil layer 1 are completely the same as those of the example 1.
Comparative example 2
The comparative example provides a method for preparing a composite foil, the method comprising the steps of:
(1) adding polymer polyethylene glycol polyacrylate into an organic solvent dimethylacetamide under the environment of a dew point of less than or equal to-40 ℃, and mixing under an ultrasonic condition to obtain a polymer solution with the concentration of 30 wt%;
(2) the surface of the stainless steel layer 1 was coated with a polymer solution to a thickness of 3 μm, and dried at 80 ℃ for 30 hours to form a polymer layer 2, the polymer layer 2 having an average pore size of 0.3 mm.
The composite foil prepared by the comparative example only comprises the stainless steel layer 1 and the polymer layer 2, and compared with the example 1, the outermost aluminum foil layer 1 is lacked, and the operation steps and the process conditions adopted in the coating process of the polymer layer 2 are completely the same as those of the example 1.
The composite foils prepared in examples 1 to 5 and comparative examples 1 to 2 were used as electrode sheet substrates, and after coating the positive electrode slurry on the surface of the composite foil, the positive electrode sheet was obtained by drying, rolling and slicing, and after coating the negative electrode slurry on the surface of the other composite foil, the negative electrode sheet was obtained by drying, rolling and slicing. And (3) assembling the positive plate and the negative plate respectively as a battery positive electrode and a battery negative electrode, and the sulfide solid electrolyte layer as a diaphragm to obtain the lithium battery cell.
And (3) carrying out the following safety performance tests on the battery core of the lithium ion battery:
(1) narrow face extrusion test: each of the examples and comparative examples was prepared by taking 10 cells, placing the cell side upright between two parallel plates after charging, gradually pressurizing to 17.2MPa, maintaining the pressure for 1min, then releasing the pressure, observing for 1h, and regarding the cell as passing the test without ignition and explosion.
(2) And (3) overcharging test: each of the examples and comparative examples was prepared by taking 10 cells, placing the cells at 23 ± 5 ℃, discharging the cells to 3.0V, charging the cells to 5V with a current of 3C rate, decreasing the current to approximately 0A at a certain voltage, monitoring the temperature change of the battery, stopping the experiment when the temperature decreases by about 10 ℃ below the peak value, observing the state of the cells, and considering that the cells did not ignite and do not explode as passing the test.
(3)150 ℃ hot box test: each of the examples and comparative examples was prepared by taking 10 cells, placing the cells in a hot box after charging, raising the temperature to 150 ± 2 ℃ at a rate of 5 ± 2 ℃/min and maintaining the temperature for 10min, recording the surface temperature of the battery, observing the state of the cells, and considering that the cells pass the test without ignition and explosion.
(4) And (3) testing against acupuncture: each of the examples and comparative examples was prepared by taking 10 cells, fully charging them, piercing the cells with a 3mm needle at a piercing speed of 50mm/s, recording the surface temperature of the battery, observing the state of the cells, and considering the cells as passing the test without firing and without explosion.
(5) Short circuit test: in each of the examples and comparative examples, 10 cells were taken, fully charged, the positive electrode of the cell was nickel-plated, and then the positive and negative electrodes were connected by using wires of different internal resistances of 30m Ω and 45m Ω, the temperature change of the battery was monitored, and when the temperature decreased by about 10 ℃ below the peak value, the test was stopped, the state of the cell was observed, and it was regarded that the cell passed the test without ignition and explosion.
The safety performance test results obtained by adopting the test method one by one are shown in table 1.
As can be seen from the test results provided in table 1, compared with the comparative examples, the safety performance tests of examples 1 to 6 all pass, which indicates that the safety performance of the battery cell prepared by the method provided by the invention is significantly improved, because the composite foil with a three-layer structure is designed as the electrode plate substrate, the aluminum foil layer 1 is used as the electrode plate substrate, when needling is performed, the current of the aluminum foil layer 1 is too large, and the aluminum foil layer 1 is fused; the effect of polymer layer 2 lies in, because the diameter of needle is greater than the aperture of polymer layer 2, when the needle penetrated aluminium foil layer 1 and pierces polymer layer 2, the polymer can wrap up the syringe needle, increases insulating, and stainless steel layer 1 is hugged closely to polymer layer 2 simultaneously, can reduce the piece, prevents the short circuit, reduces short-circuit current, has greatly improved the anti-needling ability security of battery.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. The utility model provides an improve composite foil of lithium ion battery security which characterized in that, composite foil including the substrate layer, polymer layer and the aluminium foil layer of range upon range of setting in proper order.
2. The composite foil material of claim 1, wherein the substrate layer is a stainless steel layer;
preferably, the polymer layer comprises a polymer;
preferably, the polymer comprises one or a combination of at least two of polyethylene glycol acrylate, polydivinyl sulfide, polyvinylidene fluoride, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polymethyl methacrylate, polytetrafluoroethylene, polypropylene carbonate, polyethylene carbonate or polyvinyl acetate.
3. The composite foil according to claim 1 or 2, wherein the polymer layer has a pore size of 0.3 to 0.8 mm;
preferably, the thickness of the polymer layer is 3-5 μm;
preferably, the thickness of the aluminum foil layer is 1-2 μm.
4. A method of producing a composite foil according to any one of claims 1 to 3, characterized in that the method comprises:
and coating a polymer solution on the surface of the substrate layer, drying to form a polymer layer, and depositing on the surface of the polymer layer to form an aluminum foil layer to obtain the composite foil.
5. The method according to claim 4, wherein the polymer solution is prepared by the following method:
adding a polymer into an organic solvent in an environment with the dew point less than or equal to-40 ℃, and mixing to obtain a polymer solution;
preferably, the polymer comprises one or a combination of at least two of polyethylene glycol acrylate, polydivinyl sulfide, polyvinylidene fluoride, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropylene, polyethylene oxide, polymethyl methacrylate, polytetrafluoroethylene, polypropylene carbonate, polyethylene carbonate or polyvinyl acetate;
preferably, the organic solvent comprises one or a combination of at least two of dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, acetonitrile or N-methylpyrrolidone;
preferably, the polymer accounts for 30-50 wt% of the polymer solution.
6. The preparation method according to claim 4 or 5, wherein the drying temperature is 80-90 ℃;
preferably, the drying time is 20-30 h.
7. The method according to any one of claims 4 to 6, wherein the deposition is by evaporation;
preferably, the evaporation process comprises: heating and melting solid aluminum in a vacuum environment until the solid aluminum is evaporated to form gaseous aluminum, depositing the gaseous aluminum on the surface of the polymer layer, and cooling and reducing to obtain an aluminum foil layer;
preferably, the degree of vacuum is 1.3X 10-2～1.3×10-3Pa；
Preferably, the solid aluminum is heated to 1200-1400 ℃;
preferably, the cooling temperature is-18 to-15 ℃.
8. An electrode sheet, characterized in that the electrode sheet comprises the composite foil according to any one of claims 1 to 3, and a positive electrode material layer or a negative electrode material layer provided on the surface of the composite foil.
9. The preparation method of the electrode sheet according to claim 8, characterized by comprising the following steps:
coating the positive electrode slurry or the negative electrode slurry on the surface of the composite foil material as claimed in any one of claims 1 to 3, and then sequentially drying, rolling and slicing to obtain the electrode slice.
10. A lithium ion battery, characterized in that the lithium ion battery employs the electrode sheet of claim 8 as an electrode.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114335557A (en) * | 2021-11-30 | 2022-04-12 | 蜂巢能源科技有限公司 | Composite foil, preparation method, current collector and lithium ion battery |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108777308A (en) * | 2018-05-30 | 2018-11-09 | 中航锂电（洛阳）有限公司 | A kind of collector and preparation method thereof, electrochemical energy storage device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108777308A (en) * | 2018-05-30 | 2018-11-09 | 中航锂电（洛阳）有限公司 | A kind of collector and preparation method thereof, electrochemical energy storage device |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114335557A (en) * | 2021-11-30 | 2022-04-12 | 蜂巢能源科技有限公司 | Composite foil, preparation method, current collector and lithium ion battery |
| CN114335557B (en) * | 2021-11-30 | 2023-07-14 | 蜂巢能源科技有限公司 | Composite foil and preparation method thereof, current collector and lithium ion battery |
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