CN114709422A - Composite current collector, preparation method and lithium ion battery - Google Patents

Composite current collector, preparation method and lithium ion battery Download PDF

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Publication number
CN114709422A
CN114709422A CN202210123963.5A CN202210123963A CN114709422A CN 114709422 A CN114709422 A CN 114709422A CN 202210123963 A CN202210123963 A CN 202210123963A CN 114709422 A CN114709422 A CN 114709422A
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current collector
lithium
composite current
layer
conductive
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刘晓蕾
李黎黎
闫晟睿
高天一
胡景博
高华文
姜涛
孙焕丽
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FAW Group Corp
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FAW Group Corp
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Priority to CN202210123963.5A priority Critical patent/CN114709422A/en
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Priority to PCT/CN2022/141266 priority patent/WO2023151400A1/en
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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
    • 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
    • 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
    • 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
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/80—Porous plates, e.g. sintered carriers
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)
  • Cell Electrode Carriers And Collectors (AREA)

Abstract

The invention provides a composite current collector, a preparation method and a lithium ion battery, wherein the composite current collector consists of a porous foil, a lithium supplement layer and a conductive safety layer made of a thermosensitive material; determining the material types and thicknesses of the porous foil, the lithium supplement layer and the conductive safety layer of the thermosensitive material according to the thickness and the porosity of the porous foil; compounding a current collector and a conductive safety layer of a thermosensitive material by a coating method and a dip-coating method, and coating an active material on the prepared composite current collector; the lithium ion battery comprises a positive pole piece, a diaphragm and a negative pole piece, wherein the current collectors of the positive pole piece and the negative pole piece can be composite current collectors, and active substances are coated on the two sides of the composite current collectors to prepare the pole pieces which can be directly applied to the battery. According to the invention, the lightweight of the metal current collector is realized through pore forming, the first efficiency of the negative active material and the energy density of the lithium ion battery are improved, and the huge harm caused by thermal diffusion of the lithium ion battery is reduced or even avoided.

Description

Composite current collector, preparation method and lithium ion battery
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a composite current collector, a preparation method and a lithium ion battery.
Background
The lithium ion battery has been widely used due to its excellent performance indexes, especially good cycle life, high working voltage, no memory effect and less pollution. Including various electric tools, electric vehicles, large-scale energy storage power systems and other different fields.
In recent years, the new energy market is continuously developed and matured, the permeability of the electric automobile reaches over 10% in 2021, and meanwhile, the endurance requirement of a user on the whole automobile is continuously improved. The driving range of the 2021 year passenger vehicle generally reaches more than 500km, which means that the demand of the lithium ion battery with high energy density is remarkably improved. However, the energy density is increasing and is often reduced to a different extent for the safety thereof, and in order to solve this contradictory problem, it is necessary to make comprehensive innovative design from the viewpoint of the structure and material of the lithium ion battery, and particularly, to make innovative design on the current collector.
The prior art discloses multilayer materials comprising a solid substrate and at least two superimposed solid layers containing particles of an electrochemically active material, a first solid layer being attached to the substrate and a second solid layer being attached to the first solid layer. The multilayer material has a constant thickness of the upper layer of not less than 95% and a penetration depth of the second solid layer into the first solid layer of less than 10% of the first solid layer, and as an electrode component enables the production of generators with a low risk of ultra-composite degradation. However, since the current collector layer is not adjusted, and at the same time, the current collector layer is a multi-layer material which is a positive electrode material or a negative electrode material with electrochemical activity, although the materials with high energy density and low energy density are adopted for multi-layer matching, the safety can be improved only by greatly sacrificing the energy density, and even the contribution to the improvement of the safety is almost zero. Compared with the scheme, the invention not only performs light weight treatment on the current collector, but also adopts a high energy density system as the active material of the lithium ion battery, and can realize the improvement of the safety of the lithium ion battery through the heat-sensitive material, namely, the double improvement of high energy density and safety is realized.
The prior art also discloses a current collector, a pole piece thereof and a battery. The current collector comprises an insulating layer and a conductive layer, wherein the insulating layer is used for bearing the conductive layer; the conducting layer is used for bearing the electrode active material layer, the conducting layer is located on at least one surface of the insulating layer, the thickness of the conducting layer is D2, D2 satisfies: d2 is more than or equal to 300nm and less than or equal to 2 mu m, and the current collector further comprises a protective layer arranged on at least one surface of the conductive layer. The current collector can improve the short-circuit resistance when a short circuit occurs under the abnormal condition of the battery, greatly reduce the short-circuit current, greatly reduce the heat generation amount of the short circuit, improve the safety performance of the battery, simultaneously improve the mechanical strength of the conducting layer by the protective layer, further improve the safety performance of the battery, simultaneously prevent the conducting layer from being damaged or generate the phenomena of oxidation, corrosion and the like, and obviously improve the working stability and the service life of the current collector. However, the process is complex and expensive, and because the conductive layer needs to form a good contact interface with the insulating layer, if a mechanical rolling mode is adopted, the requirements on the thickness and strength of the insulating layer are high, and the thickness control of the composite current collector is difficult to ensure; if a glue bonding mode is adopted, the types of the selectable glues are few, and high-temperature or long-time standing is needed to realize the bonding effect, so that the production efficiency is low; if a vacuum evaporation mode is adopted, a composite current collector with good performance can be obtained, but the equipment and the process have high cost and are not beneficial to wide application.
Disclosure of Invention
The present invention aims to provide a composite current collector, a method for preparing the composite current collector, and a lithium ion battery, so as to solve the problem of dual improvement of high energy density and safety. The energy density and the safety of the lithium ion battery are further improved by combining a composite current collector of the lithium supplement layer and the conductive thermosensitive material layer through a lightweight technology.
The purpose of the invention is realized by the following technical scheme:
a composite current collector consists of a porous foil, a lithium supplement layer and a conductive safety layer made of a thermosensitive material; the porous foil is made of a metal conductive material or a carbon-based conductive material, and the porosity of the material is 0-60%; the lithium supplement layer is made of a lithium metal material or a lithium metal compound material; the material of the conductive safety layer of the thermosensitive material consists of a material with a positive temperature coefficient, a conductive material and an adhesive.
Further, the metal conductive material is preferably copper, aluminum, nickel, titanium; the carbon-based conductive material is preferably hard carbon, soft carbon, graphite, acetylene black, graphene or carbon nanotubes.
Further, the thickness of the composite current collector is 5um ~ 25um, and the thickness of the porous foil material is 4um ~ 20um, and the thickness of the lithium supplement layer material is 5um ~ 15um, and the thickness of the conductive safety layer of the thermosensitive material is 3um ~ 15 um.
Further, the lithium metal chemical material used for the positive electrode partial lithium supplement layer is preferably a lithium-rich compound or a nanocomposite material based on a conversion reaction, and the lithium metal chemical material used for the negative electrode partial lithium supplement layer is preferably a lithium metal tape, a stabilized lithium metal powder, a lithium silicide powder.
Further, the positive temperature coefficient material is a high molecular polymer material, preferably high-density polyethylene, polyvinylidene fluoride, carboxylic acid modified polyvinylidene fluoride, acrylic acid modified polyvinylidene fluoride, polyvinylidene chloride, carboxylic acid modified polyvinylidene chloride, acrylic acid modified polyvinylidene chloride, polyvinylidene fluoride copolymer, polyvinylidene chloride copolymer material; it may also be an expandable graphite-based material, preferably expandable graphite in the form of particles, having a moderate initial expansion temperature.
Furthermore, the weight percent of the positive temperature coefficient material is 75-90%, the weight percent of the conductive material is 5-15%, and the weight percent of the adhesive material is 5-15%.
Furthermore, the conductive material belongs to one of conductive materials and carbon-based conductive materials, and the metal conductive material is preferably copper, aluminum, nickel or titanium metal particle materials; the carbon-based conductive material is preferably selected from hard carbon, soft carbon, graphite, acetylene black, graphene and carbon nanotube materials.
Further, the adhesive is preferably a hydroxyl derivative material of polyacrylate, polycarbonate, polyethylene oxide, rubber, polyurethane, sodium carboxymethylcellulose, polyacrylic acid, gelatin, chitosan, cyclodextrin.
A preparation method of a composite current collector comprises the following steps:
A. forming a porous foil by dense perforation or electrodeposition;
B. determining the material types and thicknesses of the porous foil, the lithium supplement layer and the conductive safety layer of the thermosensitive material according to the thickness and porosity of the porous foil;
C. the compounding of the current collector and the conductive safety layer of the thermosensitive material is realized through a coating method and a dip-coating method, and the coating of the active material is carried out on the prepared composite current collector.
A lithium ion battery comprises a positive pole piece, a diaphragm and a negative pole piece, wherein a composite current collector can be selected as current collectors of the positive pole piece and the negative pole piece, active substances are coated on two sides of the composite current collector, and the prepared positive pole piece and the prepared negative pole piece can be directly applied to the battery.
Compared with the prior art, the invention has the beneficial effects that:
1. the thickness of the aluminum foil current collector of the positive electrode material and the copper foil current collector of the negative electrode can be reduced by 30% compared with the thickness of the existing material, meanwhile, the light weight of the metal current collector is realized through a pore-forming technology, and in order to ensure the use strength of the porous thin substrate, the substrate is subjected to composite treatment through physical and chemical technologies, so that the porosity ratio can be further increased to 50%;
2. the lithium supplementing layer of lithium metal or lithium metal compound can be covered on the surface and the holes, so that the lithium supplementing layer can be used for supplementing lithium when a silicon-containing negative electrode material is formed for the first time, the effect of improving the first efficiency of a negative electrode active material is achieved, and a new solution is further provided for improving the energy density of the lithium ion battery;
3. the conductive heat-sensitive material layer can be directly covered on the surface and the holes, or the conductive heat-sensitive material layer can be covered on the surface of the lithium metal or the lithium metal compound, so that the lithium ion battery is ensured to have higher energy density in normal use, and meanwhile, when the lithium ion battery is out of control thermally, the heat-sensitive material realizes the rapid rise of the internal resistance of the lithium ion battery in modes of expansion, electrolyte absorption and the like, the thermal runaway chain reaction of the lithium ion battery is cut off, and the huge harm caused by the thermal diffusion of the lithium ion battery is reduced or even avoided.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic view of current collectors of different porosities;
fig. 2 a composite current collector;
fig. 3 is a schematic of an electrode fabricated using a composite current collector.
Detailed Description
The invention is further illustrated by the following examples:
the present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present invention, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
The composite current collector comprises a porous foil (shown as a mark 3 in figure 2) with a light weight design, lithium supplement layers (shown as marks 2 and 4 in figure 2) and conductive safety layers (shown as marks 1 and 5 in figure 2) of a thermosensitive material, and the thickness of the composite current collector is 5-25 um, as shown in figure 2.
The material, porosity and thickness design of the composite current collector needs to meet certain mechanical strength, if the strength is too weak, the composite process of the conductive safety protection layer of the heat-sensitive material cannot be met, and if the strength is too strong, design redundancy exists.
The porous foil material is one of a metal conductive material and a carbon-based conductive material; the metal conductive material is preferably copper, aluminum, nickel, titanium and the like; the carbon-based conductive material is preferably hard carbon, soft carbon, graphite, acetylene black, graphene, carbon nanotubes and the like.
The porosity of the porous foil material is 0% -60%, as shown in figure 1.
The thickness of the porous foil material is 4 um-20 um.
The lithium supplementing layer is made of lithium metal material or lithium metal compound material, and the lithium metal chemical material which can be used for the lithium supplementing layer of the positive electrode part is preferably a lithium-rich compound, such as Li2NiO2、Li2NiCuO2Etc., or nanocomposites based on conversion reactions, such as Nano-M/LiF, Nano-M/LiO, etc., where M can be Co, Ni, Fe elements; the lithium-supplementing layer used for the negative electrode portion is preferably a metallic lithium tape, Stabilized Lithium Metal Powder (SLMP), lithium silicide powder, or the like.
The thickness of the lithium supplement layer material is 5 um-15 um.
The material of the conductive safety layer in the thermosensitive material layer consists of a material with a positive temperature coefficient, a conductive material and an adhesive.
The positive temperature coefficient material can be a high molecular polymer material, preferably high-density polyethylene, polyvinylidene fluoride, carboxylic acid modified polyvinylidene fluoride, acrylic acid modified polyvinylidene fluoride, polyvinylidene chloride, carboxylic acid modified polyvinylidene chloride, acrylic acid modified polyvinylidene chloride, polyvinylidene fluoride copolymer, polyvinylidene chloride copolymer material and the like; it may also be an expandable graphite-based material, preferably expandable graphite in the form of particles, having a moderate initial expansion temperature.
The weight percent of the positive temperature coefficient material is 75-90%.
The conductive material belongs to one of conductive materials and carbon-based conductive materials, and the metal conductive material is preferably copper, aluminum, nickel, titanium metal particle materials and the like; the carbon-based conductive material is preferably selected from hard carbon, soft carbon, graphite, acetylene black, graphene, carbon nanotube materials and the like.
The weight percent of the conductive material is 5-15%.
The adhesive is preferably polyacrylate, polycarbonate, polyethylene oxide, rubber, polyurethane, sodium carboxymethyl cellulose, polyacrylic acid, gelatin, chitosan, hydroxyl derivative materials of cyclodextrin, and the like.
5-15 wt% of the adhesive material.
The thickness of the conductive safety layer of the thermosensitive material is 3-15 um.
The composite current collector can realize the composition of the current collector and the conductive safety layer of the thermosensitive material by a coating method and a dip coating method, and the coating method is preferably roll coating, extrusion coating, blade coating, gravure coating and the like.
A preparation method of a composite current collector comprises the following steps:
A. forming a porous foil by dense perforation or electrodeposition;
B. determining the material types and thicknesses of the porous foil, the lithium supplement layer and the conductive safety layer of the thermosensitive material according to the thickness and porosity of the porous foil;
C. the compounding of the current collector and the conductive safety layer of the thermosensitive material is realized through a coating method and a dip-coating method, and the coating of the active material is carried out on the prepared composite current collector.
The embodiment further provides a lithium ion battery, which includes a positive electrode plate, a diaphragm, and a negative electrode plate, wherein the current collectors of the positive electrode plate and the negative electrode plate can be composite current collectors (marks 2-3-4-5-6 in fig. 3), and as shown in fig. 3, active materials ( marks 1 and 7 in fig. 3) are coated on both sides of the safe composite current collectors, and the prepared positive electrode plate and the prepared negative electrode plate can be directly applied to the battery.
The battery of the application can be coiled and also can be laminated. The battery of the present application may be one of a lithium ion secondary battery, a lithium primary battery, a sodium ion battery, and a magnesium ion battery. But is not limited thereto.
Example 1
Preparing a composite current collector:
selecting a metal aluminum foil with 50% porosity and 5um thickness, and carrying out decontamination and deoiling treatment on the surface of the aluminum foil for later use; adopting expandable graphite: acetylene black: CMC: SBR, 80% in weight percent: 5%: 5%: stirring 5% of the aluminum foil in deionized water, forming a coating with uniform thickness on the surface of the aluminum foil in a transfer coating mode after uniform stirring, and then drying at 80 ℃ for later use; with Li2NiO 2: PVDF: SP, 96% in wt.%: 2.5%: stirring the mixture in NMP in a proportion of 1.5%, and after the mixture is uniformly stirred, forming a coating with uniform thickness on the surface of the aluminum foil in a transfer coating mode to obtain the composite current collector.
Example 2
Selecting a metal copper foil with 70% porosity and 3um thickness, and carrying out decontamination and deoiling treatment on the surface of the copper foil for later use; adopting carboxylic acid modified polyvinylidene fluoride: graphite: polyacrylic acid, 60% by weight: 25%: stirring 15% of the copper foil in an NMP solvent, after uniformly stirring, forming a coating with uniform thickness on the surface of the copper foil by adopting a lifting and dip-coating mode, and then drying at 80 ℃ for later use; and (3) carrying out mechanical rolling compounding by adopting a metal lithium belt to obtain the composite current collector.
Example 3
Preparation of positive pole piece, negative pole piece and battery with safe composite current collector
Positive pole piece: ternary materials NCM811(lini0.8co0.1mn0.1o2), SP and PVDF were used, with NMP as the solvent, in a 95%: 2%: 3 percent of the aluminum-based material is uniformly stirred and then coated on a current collector, the current collector is an aluminum foil which is prepared by the method and is made of an aluminum-based material safety composite current collector and a conventional 12um aluminum foil, the aluminum foil is used as an anode active material layer, the aluminum foil is dried at 85 ℃ and then is subjected to cold pressing, then the aluminum foil is subjected to edge cutting, piece cutting and strip splitting, and is dried for 4 hours at 85 ℃ under a vacuum condition, and a tab is welded to prepare an anode piece.
Negative pole piece: graphite, SP, CMC and SBR are adopted, deionized water is used as a solvent, and the weight percentage is as follows, and is as follows (96%: 1%: 1%: 1.5 percent of the copper-based material safety composite current collector and a conventional copper foil of 8 mu m are adopted as the current collector, the current collector is prepared by the method and is coated on the current collector, the current collector is used as a negative active material layer, the negative active material layer is dried at 85 ℃ and then is subjected to cold pressing, and then the negative active material layer is subjected to edge cutting, sheet cutting and strip splitting, and is dried for 4 hours at 85 ℃ under a vacuum condition, and a tab is welded to prepare a negative pole piece.
Preparing a battery: through a conventional battery manufacturing process, a positive electrode plate (compacted density: 3.4g/cm3), a PP/PE/PP diaphragm and a negative electrode plate (compacted density: 1.6g/cm3) are wound together into a bare cell, then the bare cell is placed into a battery shell, electrolyte (EC: EMC volume ratio is 3:7, and LiPF6 is 1mol/L) is injected, and then the procedures of sealing, formation and the like are carried out, so that the lithium ion battery is finally obtained, wherein the procedures are shown in Table 1.
Example 4
Testing of the battery:
and (4) safety testing: and comparing the safety performance of the battery by adopting a needling test, fully charging the secondary battery to the charging cut-off voltage at the current of 1C, then charging at a constant voltage until the current is reduced to 0.05C, and stopping charging. The used high temperature resistant steel needle (the conical angle of the needle point is 45 degrees) penetrates through the battery from the direction vertical to the polar plate of the battery at the speed of 25mm/s, the penetrating position is close to the geometric center of the punctured surface, the steel needle stays in the battery, and whether the battery has the phenomena of combustion and explosion or not is observed.
And (3) cycle testing: charging to cut-off voltage by adopting 0.3C, then charging to current to 0.05C by adopting constant voltage, stopping charging, standing for 5min, then discharging to cut-off voltage by adopting 1C, cycling to 1000 weeks according to the program, and taking the discharge capacity as the calculation standard of the capacity retention rate.
TABLE 1 Battery design
Figure BDA0003499636060000101
TABLE 2 Battery test results
Average capacity retention at 1000 weeks% The result of acupuncture
Battery
1 88.3％ 5 passes, 5 fails
Battery 2 88.8％ 8 passes, 2 fails
Battery 3 88.2％ 9 passes, 1 fails
Battery 4 88.4％ 10 all pass through
The current collectors are metal aluminum foils and metal copper foils used by the universal positive and negative electrodes of the lithium ion battery, and can be realized in a mode of forming microporous foils through intensive punching or electrodeposition and the like in the foil manufacturing process. The composite current collector comprises the porous metal foil with light weight design, the lithium metal or the lithium metal compound and the conductive safety protection layer with heat-sensitive property, and the composite layer can improve the mechanical strength of the porous metal foil and greatly improve the porosity design of the metal foil, so that the energy density of the lithium ion battery is improved. Meanwhile, lithium metal or lithium metal compound can supplement lithium when a silicon-containing negative electrode material is used in the first formation, the effect of improving the first efficiency of a negative electrode active material is achieved, a new solution is further provided for improving the energy density of the lithium ion battery, in addition, due to the existence of a conductive thermosensitive material layer, when the abnormal condition of the battery has a thermal runaway risk, the large current enables the temperature of a thermosensitive material base material to rapidly rise to the melting temperature of a polymer, the volume of the thermosensitive material base material rapidly expands and the conductive filler is dispersed in the whole volume along with the transition from a crystalline phase to an amorphous phase, the conductive filler migrates and diffuses in the base body, a large number of conductive chains are damaged, the resistance is rapidly increased, the loop current is rapidly reduced, the conductive network can be rapidly cut off, and meanwhile, part of combustible electrolyte is absorbed, the heat produced by the battery is reduced, and the safety performance of the battery is improved.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the particular embodiments described herein, and that various obvious changes, rearrangements and substitutions will now be apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. A composite current collector, comprising: the lithium ion battery is composed of a porous foil, a lithium supplement layer and a conductive safety layer made of a thermosensitive material; the porous foil is made of a metal conductive material or a carbon-based conductive material, and the porosity of the material is 0-60%; the lithium supplement layer is made of a lithium metal material or a lithium metal compound material; the material of the conductive safety layer of the thermosensitive material consists of a material with a positive temperature coefficient, a conductive material and an adhesive.
2. The composite current collector of claim 1, wherein: the metal conductive material is preferably copper, aluminum, nickel or titanium; the carbon-based conductive material is preferably selected from hard carbon, soft carbon, graphite, acetylene black, graphene and carbon nanotubes.
3. The composite current collector of claim 1, wherein: composite current collector thickness is 5um ~ 25um, and the thickness of porous foil material is 4um ~ 20um, and the thickness of mending the lithium layer material is 5um ~ 15um, and the thickness of the electrically conductive safety layer of thermosensitive material is 3um ~ 15 um.
4. The composite current collector of claim 1, wherein: the lithium metal chemical material used for the positive electrode partial lithium supplement layer is preferably a lithium-rich compound or a nanocomposite material based on a conversion reaction, and the lithium metal chemical material used for the negative electrode partial lithium supplement layer is preferably a lithium metal tape, a stabilized lithium metal powder or a lithium silicide powder.
5. The composite current collector of claim 1, wherein: the positive temperature coefficient material is a high molecular polymer material, preferably high-density polyethylene, polyvinylidene fluoride, carboxylic acid modified polyvinylidene fluoride, acrylic acid modified polyvinylidene fluoride, polyvinylidene chloride, carboxylic acid modified polyvinylidene chloride, acrylic acid modified polyvinylidene chloride, polyvinylidene fluoride copolymer and polyvinylidene chloride copolymer materials; it may also be an expandable graphite-based material, preferably expandable graphite in the form of particles, having a moderate initial expansion temperature.
6. The composite current collector of claim 1, wherein: the weight percent of the positive temperature coefficient material is 75-90%, the weight percent of the conductive material is 5-15%, and the weight percent of the adhesive material is 5-15%.
7. The composite current collector of claim 1, wherein: the conductive material belongs to one of conductive materials and carbon-based conductive materials, and the metal conductive material is preferably copper, aluminum, nickel or titanium metal particle materials; the carbon-based conductive material is preferably selected from hard carbon, soft carbon, graphite, acetylene black, graphene and carbon nanotube materials.
8. The composite current collector of claim 1, wherein: the adhesive is preferably polyacrylate, polycarbonate, polyethylene oxide, rubber, polyurethane, sodium carboxymethyl cellulose, polyacrylic acid, gelatin, chitosan, and hydroxyl derivative material of cyclodextrin.
9. The preparation method of the composite current collector is characterized by comprising the following steps of:
A. forming a porous foil by dense perforation or electrodeposition;
B. determining the material types and thicknesses of the porous foil, the lithium supplement layer and the conductive safety layer of the thermosensitive material according to the thickness and porosity of the porous foil;
C. the compounding of the current collector and the conductive safety layer of the thermosensitive material is realized through a coating method and a dip-coating method, and the coating of the active material is carried out on the prepared composite current collector.
10. A lithium ion battery, characterized by: the current collectors of the positive pole piece and the negative pole piece can be composite current collectors, active substances are coated on the two sides of the composite current collectors, and the positive pole piece and the negative pole piece which are prepared can be directly applied to a battery.
CN202210123963.5A 2022-02-10 2022-02-10 Composite current collector, preparation method and lithium ion battery Pending CN114709422A (en)

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CN202210123963.5A CN114709422A (en) 2022-02-10 2022-02-10 Composite current collector, preparation method and lithium ion battery
PCT/CN2022/141266 WO2023151400A1 (en) 2022-02-10 2022-12-23 Composite current collector and preparation method therefor, and lithium ion battery

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CN115810759A (en) * 2022-10-17 2023-03-17 宁德时代新能源科技股份有限公司 Flexible composite current collector, preparation method thereof, pole piece and battery
CN116598419A (en) * 2023-06-29 2023-08-15 广州方邦电子股份有限公司 Composite foil, battery pole piece and electrochemical energy storage device
WO2023151400A1 (en) * 2022-02-10 2023-08-17 中国第一汽车股份有限公司 Composite current collector and preparation method therefor, and lithium ion battery
WO2024016891A1 (en) * 2022-07-19 2024-01-25 宁德时代新能源科技股份有限公司 Pre-lithiated electrode plate and preparation method therefor, secondary battery, and electric device
CN117878432A (en) * 2024-03-11 2024-04-12 蜂巢能源科技股份有限公司 Battery cell, and preparation method and application thereof

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WO2023151400A1 (en) * 2022-02-10 2023-08-17 中国第一汽车股份有限公司 Composite current collector and preparation method therefor, and lithium ion battery
CN115000414A (en) * 2022-06-15 2022-09-02 欣旺达惠州动力新能源有限公司 Current collector and preparation method and application thereof
WO2024016891A1 (en) * 2022-07-19 2024-01-25 宁德时代新能源科技股份有限公司 Pre-lithiated electrode plate and preparation method therefor, secondary battery, and electric device
CN115810759A (en) * 2022-10-17 2023-03-17 宁德时代新能源科技股份有限公司 Flexible composite current collector, preparation method thereof, pole piece and battery
CN116598419A (en) * 2023-06-29 2023-08-15 广州方邦电子股份有限公司 Composite foil, battery pole piece and electrochemical energy storage device
CN117878432A (en) * 2024-03-11 2024-04-12 蜂巢能源科技股份有限公司 Battery cell, and preparation method and application thereof
CN117878432B (en) * 2024-03-11 2024-05-31 蜂巢能源科技股份有限公司 Battery cell, and preparation method and application thereof

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